Expansion of profibrotic monocyte-derived alveolar macrophages in patients with persistent respiratory symptoms and radiographic abnormalities after COVID-19

Barbry_unpubl

Duong_lungMAP_unpubl

Schiller_2021

Schultze_unpubl

CZ_CELLXGENE

An integrated cell atlas of the human lung in health and disease (full)

An integrated cell atlas of the human lung in health and disease (core)

The integrated Human Lung Cell Atlas (HLCA) v1.0

Lung Network

Lung Network - Overview

Rationale: The respiratory tract constitutes an elaborated line of defense that is based on a unique cellular ecosystem. Single-cell profiling methods enable the investigation of cell population distributions and transcriptional changes along the airways.Methods: We have explored the cellular heterogeneity of the human airway epithelium in 10 healthy living volunteers by single-cell RNA profiling. 77,969 cells were collected at 35 distinct locations, from the nose to the 12th division of the airway tree.Results: The resulting atlas is composed of a high percentage of epithelial cells (89.1%), but also immune (6.2%) and stromal (4.7%) cells with distinct cellular proportions in different regions of the airways. It reveals differential gene expression between identical cell types (suprabasal, secretory, and multiciliated cells) from the nose (MUC4, PI3, SIX3) and tracheobronchial (SCGB1A1, TFF3) airways. By contrast, cell-type specific gene expression is stable across all tracheobronchial samples. Our atlas improves the description of ionocytes, pulmonary neuro-endocrine (PNEC) and brush cells, and identifies a related population of NREP-positive cells. We also report the association of KRT13 with dividing cells that are reminiscent of previously described mouse “hillock” cells, and with squamous cells expressing SCEL, SPRR1A/B.Conclusions: Robust characterization of a single-cell cohort in healthy airways establishes a valuable resource for future investigations. The precise description of the continuum existing
from the nasal epithelium to successive divisions of the airways and the stable gene expression profile of these regions better defines conditions under which relevant tracheobronchial proxies of human respiratory diseases can be developed.

A Single-Cell Atlas of the Human Healthy Airways

Human lungs enable efficient gas exchange and form an interface with the environment, which depends on mucosal immunity for protection against infectious agents. Tightly controlled interactions between structural and immune cells are required to maintain lung homeostasis. Here, we use single-cell transcriptomics to chart the cellular landscape of upper and lower airways and lung parenchyma in healthy lungs, and lower airways in asthmatic lungs. We report location-dependent airway epithelial cell states and a novel subset of tissue-resident memory T cells. In the lower airways of patients with asthma, mucous cell hyperplasia is shown to stem from a novel mucous ciliated cell state, as well as goblet cell hyperplasia. We report the presence of pathogenic effector type 2 helper T cells (T<sub>H</sub>2) in asthmatic lungs and find evidence for type 2 cytokines in maintaining the altered epithelial cell states. Unbiased analysis of cell-cell interactions identifies a shift from airway structural cell communication in healthy lungs to a T<sub>H</sub>2-dominated interactome in asthmatic lungs.

A cellular census of human lungs identifies novel cell states in health and in asthma

The gene expression program underlying the specification of human cell types is of fundamental interest. We generated human cell atlases of gene expression and chromatin accessibility in fetal tissues. For gene expression, we applied three-level combinatorial indexing to >110 samples representing 15 organs, ultimately profiling ~4 million single cells. We leveraged the literature and other atlases to identify and annotate hundreds of cell types and subtypes, both within and across tissues. Our analyses focused on organ-specific specializations of broadly distributed cell types (such as blood, endothelial, and epithelial), sites of fetal erythropoiesis (which notably included the adrenal gland), and integration with mouse developmental atlases (such as conserved specification of blood cells). These data represent a rich resource for the exploration of in vivo human gene expression in diverse tissues and cell types.

A human cell atlas of fetal gene expression.

We present a multiomic cell atlas of human lung development that combines single cell RNA and ATAC sequencing, high throughput spatial transcriptomics and single cell imaging. Coupling single cell methods with spatial analysis has allowed a comprehensive cellular survey of the epithelial, mesenchymal, endothelial and erythrocyte/leukocyte compartments from 5-22 post conception weeks. We identify new cell states in all compartments. These include developmental-specific secretory progenitors that resemble cells in adult fibrotic lungs and a new subtype of neuroendocrine cell related to human small cell lung cancer; observations which strengthen the connections between development and disease/regeneration. Our datasets are available for the community to download and interact with through our web interface ( https://fetal-lung.cellgeni.sanger.ac.uk ). Finally, to illustrate its general utility, we use our cell atlas to generate predictions about cell-cell signalling and transcription factor hierarchies which we test using organoid models. Highlights Spatiotemporal atlas of human lung development from 5-22 post conception weeks identifies 147 cell types/states. Tracking the developmental origins of multiple cell compartments, including new progenitor states. Functional diversity of fibroblasts in distinct anatomical signalling niches. Resource applied to interrogate and experimentally test the transcription factor code controlling neuroendocrine cell heterogeneity and the origins of small cell lung cancer.

A human fetal lung cell atlas uncovers proximal-distal gradients of differentiation and key regulators of epithelial fates

Although single-cell RNA sequencing studies have begun to provide compendia of cell expression profiles, it has been difficult to systematically identify and localize all molecular cell types in individual organs to create a full molecular cell atlas. Here, using droplet- and plate-based single-cell RNA sequencing of approximately 75,000 human cells across all lung tissue compartments and circulating blood, combined with a multi-pronged cell annotation approach, we create an extensive cell atlas of the human lung. We define the gene expression profiles and anatomical locations of 58 cell populations in the human lung, including 41 out of 45 previously known cell types and 14 previously unknown ones. This comprehensive molecular atlas identifies the biochemical functions of lung cells and the transcription factors and markers for making and monitoring them; defines the cell targets of circulating hormones and predicts local signalling interactions and immune cell homing; and identifies cell types that are directly affected by lung disease genes and respiratory viruses. By comparing human and mouse data, we identified 17 molecular cell types that have been gained or lost during lung evolution and others with substantially altered expression profiles, revealing extensive plasticity of cell types and cell-type-specific gene expression during organ evolution including expression switches between cell types. This atlas provides the molecular foundation for investigating how lung cell identities, functions and interactions are achieved in development and tissue engineering and altered in disease and evolution.

A molecular cell atlas of the human lung from single-cell RNA sequencing

Respiratory failure is the leading cause of death in patients with severe SARS-CoV-2 infection, but the host response at the lung tissue level is poorly understood. Here we performed single-nucleus RNA sequencing of about 116,000 nuclei from the lungs of nineteen individuals who died of COVID-19 and underwent rapid autopsy and seven control individuals. Integrated analyses identified substantial alterations in cellular composition, transcriptional cell states, and cell-to-cell interactions, thereby providing insight into the biology of lethal COVID-19. The lungs from individuals with COVID-19 were highly inflamed, with dense infiltration of aberrantly activated monocyte-derived macrophages and alveolar macrophages, but had impaired T cell responses. Monocyte/macrophage-derived interleukin-1β and epithelial cell-derived interleukin-6 were unique features of SARS-CoV-2 infection compared to other viral and bacterial causes of pneumonia. Alveolar type 2 cells adopted an inflammation-associated transient progenitor cell state and failed to undergo full transition into alveolar type 1 cells, resulting in impaired lung regeneration. Furthermore, we identified expansion of recently described CTHRC1+ pathological fibroblasts3 contributing to rapidly ensuing pulmonary fibrosis in COVID-19. Inference of protein activity and ligand–receptor interactions identified putative drug targets to disrupt deleterious circuits. This atlas enables the dissection of lethal COVID-19, may inform our understanding of long-term complications of COVID-19 survivors, and provides an important resource for therapeutic development.

A molecular single-cell lung atlas of lethal COVID-19

Airways conduct gases to the lung and are disease sites of asthma and cystic fibrosis. Here we study the cellular composition and hierarchy of the mouse tracheal epithelium by single-cell RNA-sequencing (scRNA-seq) and in vivo lineage tracing. We identify a rare cell type, the Foxi1+ pulmonary ionocyte; functional variations in club cells by proximodistal location; a distinct cell type in high turnover squamous epithelial structures that we term 'hillocks'; and disease-relevant subsets of tuft and goblet cells. We developed 'pulse-seq' , combining scRNA-seq and lineage tracing, to show that tuft, neuroendocrine and ionocyte cells are continually and directly replenished by basal progenitor cells. Ionocytes are the major source of transcripts of the cystic fibrosis transmembrane conductance regulator in both mouse (Cftr) and human (CFTR). Knockout of Foxi1 in mouse ionocytes causes loss of Cftr expression and disrupts airway fluid and mucus physiology, phenotypes that characterize cystic fibrosis. By associating cell-type-specific expression programs with key disease genes, we establish a new cellular narrative for airways disease.

A revised airway epithelial hierarchy includes CFTR-expressing ionocytes

The authors developed a systematic toolbox for profiling fresh and frozen clinical tumor samples using scRNA-Seq and snRNA-Seq.

A single-cell and single-nucleus RNA-seq toolbox for fresh and frozen human tumors.

Current catalogs of regulatory sequences in the human genome are still incomplete and lack cell type resolution. To profile the activity of gene regulatory elements in diverse cell types and tissues in the human body, we applied single-cell chromatin accessibility assays to 30 adult human tissue types from multiple donors. We integrated these datasets with single-cell chromatin accessibility data from 15 fetal tissue types to reveal the status of open chromatin for approximately 1.2 million candidate cis-regulatory elements (cCREs) in 222 distinct cell types comprised of >1.3 million nuclei. We used these chromatin accessibility maps to delineate cell type-specificity of fetal and adult human cCREs and to systematically interpret the noncoding variants associated with complex human traits and diseases. This rich resource provides a foundation for the analysis of gene regulatory programs in human cell types across tissues, life stages, and organ systems. Overall design: Applying single cell chromatin accessibility assays to diverse human tissue types from four donors.

A single-cell atlas of chromatin accessibility in the human genome

Ex-utero regulation of the lungs' responses to breathing air and continued alveolar development shape adult respiratory health. Applying single-cell transposome hypersensitive site sequencing (scTHS-seq) to over 80,000 cells, we assembled the first regulatory atlas of postnatal human and mouse lung alveolar development. We defined regulatory modules and elucidated new mechanistic insights directing alveolar septation, including alveolar type 1 and myofibroblast cell signaling and differentiation, and a unique human matrix fibroblast population. Incorporating GWAS, we mapped lung function causal variants to myofibroblasts and identified a pathogenic regulatory unit linked to lineage marker FGF18, demonstrating the utility of chromatin accessibility data to uncover disease mechanism targets. Our regulatory map and analysis model provide valuable new resources to investigate age-dependent and species-specific control of critical developmental processes. Furthermore, these resources complement existing atlas efforts to advance our understanding of lung health and disease across the human lifespan.

A single-cell regulatory map of postnatal lung alveologenesis in humans and mice

Single-cell transcriptomics has allowed unprecedented resolution of cell types/states in the human lung, but their spatial context is less well defined. To (re)define tissue architecture of lung and airways, we profiled five proximal-to-distal locations of healthy human lungs in depth using multi-omic single cell/nuclei and spatial transcriptomics (queryable at lungcellatlas.org ). Using computational data integration and analysis, we extend beyond the suspension cell paradigm and discover macro and micro-anatomical tissue compartments including previously unannotated cell types in the epithelial, vascular, stromal and nerve bundle micro-environments. We identify and implicate peribronchial fibroblasts in lung disease. Importantly, we discover and validate a survival niche for IgA plasma cells in the airway submucosal glands (SMG). We show that gland epithelial cells recruit B cells and IgA plasma cells, and promote longevity and antibody secretion locally through expression of CCL28, APRIL and IL-6. This new 'gland-associated immune niche' has implications for respiratory health.

A spatially resolved atlas of the human lung characterizes a gland-associated immune niche

Rationale: Despite the importance of inflammation in chronic obstructive pulmonary disease (COPD), the immune cell landscape in the lung tissue of patients with mild-moderate disease has not been well characterized at the single-cell and molecular level. Objectives: To define the immune cell landscape in lung tissue from patients with mild-moderate COPD at single-cell resolution. Methods: We performed single-cell transcriptomic, proteomic, and T-cell receptor repertoire analyses on lung tissue from patients with mild-moderate COPD (n = 5, Global Initiative for Chronic Obstructive Lung Disease I or II), emphysema without airflow obstruction (n = 5), end-stage COPD (n = 2), control (n = 6), or donors (n = 4). We validated in an independent patient cohort (N = 929) and integrated with the Hhip+/- murine model of COPD. Measurements and Main Results: Mild-moderate COPD lungs have increased abundance of two CD8+ T cell subpopulations: cytotoxic KLRG1+TIGIT+CX3CR1+ TEMRA (T effector memory CD45RA+) cells, and DNAM-1+CCR5+ T resident memory (TRM) cells. These CD8+ T cells interact with myeloid and alveolar type II cells via IFNG and have hyperexpanded T-cell receptor clonotypes. In an independent cohort, the CD8+KLRG1+ TEMRA cells are increased in mild-moderate COPD lung compared with control or end-stage COPD lung. Human CD8+KLRG1+ TEMRA cells are similar to CD8+ T cells driving inflammation in an aging-related murine model of COPD. Conclusions: CD8+ TEMRA cells are increased in mild-moderate COPD lung and may contribute to inflammation that precedes severe disease. Further study of these CD8+ T cells may have therapeutic implications for preventing severe COPD.

Activation of CD8+ T Cells in Chronic Obstructive Pulmonary Disease Lung

Rationale: Macrophages are the most abundant immune cell in the alveoli and small airways and are traditionally viewed as a homogeneous population during health. Whether distinct subsets of airspace macrophages are present in healthy humans is unknown. Single-cell RNA sequencing allows for examination of transcriptional heterogeneity between cells and between individuals. Understanding the conserved repertoire of airspace macrophages during health is essential to understanding cellular programing during disease.Objectives: We sought to determine the transcriptional heterogeneity of human cells obtained from BAL of healthy adults.Methods: Ten subjects underwent bronchoscopy with BAL. Cells from lavage were subjected to single-cell RNA sequencing. Unique cell populations and putative functions were identified. Transcriptional profiles were compared across individuals.Measurements and Main Results: We identify two novel subgroups of resident airspace macrophages-defined by proinflammatory and metallothionein gene expression profiles. We define subsets of monocyte-like cells and compare them with peripheral blood mononuclear cells. Finally, we compare global macrophage and monocyte programing between males and females.Conclusions: Healthy human airspaces contain multiple populations of myeloid cells that are highly conserved between individuals and between sexes. Resident macrophages make up the largest population and include novel subsets defined by inflammatory and metal-binding profiles. Monocyte-like cells within the airspaces are transcriptionally aligned with circulating blood cells and include a rare population defined by expression of cell-matrix interaction genes. This study is the first to delineate the conserved heterogeneity of airspace immune cells during health and identifies two previously unrecognized macrophage subsets.

Airspace Macrophages and Monocytes Exist in Transcriptionally Distinct Subsets in Healthy Adults

Chronic obstructive pulmonary disease (COPD) is a progressive disease that obstructs the airflow from the lungs, and tobacco smoking is the major cause of COPD. Here, we applied single-cell RNA sequencing to analyze COPD pathogenesis in COPD patients, non-COPD smokers and never-smokers and investigated the disease progression at single-cell resolution. By single-cell transcriptome analysis, COPD was characterized by shifts in the stromal, immune system and epithelial cell compositions. While epithelial components in never-smokers were relatively uniform, the smoker groups presented with extensive heterogeneity in epithelial cells, particularly in the alveolar type II (AT2) lineages. We identified a subpopulation of AT2 epithelial cells that emerged in smokers, such as COPD patients, and specifically expressed a series of chemokines and PD-L1. A trajectory analysis revealed that the inflammatory AT2 cell subpopulation followed a unique differentiation path, and a prediction model of cell-to-cell interactions inferred increased intercellular networks of inflammatory AT2 cells with immune and stromal cell populations. Thus, our analysis reveals a unique cellular differentiation pathway and function underlying the biological and clinical characteristics of COPD pathogenesis. Overall design: single-cell transcriptome profiling from human lung tissues of 6 COPD, 3 non-COPD smoker, and 3 never-smoker samples.

Anomalous Epithelial Variations and Ectopic Inflammatory Response in Chronic Obstructive Pulmonary Disease

A dysfunctional immune response in coronavirus disease 2019 (COVID-19) patients is a recurrent theme impacting symptoms and mortality, yet a detailed understanding of pertinent immune cells is not complete. We applied single-cell RNA sequencing to 284 samples from 196 COVID-19 patients and controls and created a comprehensive immune landscape with 1.46 million cells. The large dataset enabled us to identify that different peripheral immune subtype changes are associated with distinct clinical features, including age, sex, severity, and disease stages of COVID-19. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was found in diverse epithelial and immune cell types, accompanied by dramatic transcriptomic changes within virus-positive cells. Systemic upregulation of S100A8/A9, mainly by megakaryocytes and monocytes in the peripheral blood, may contribute to the cytokine storms frequently observed in severe patients. Our data provide a rich resource for understanding the pathogenesis of and developing effective therapeutic strategies for COVID-19.

COVID-19 immune features revealed by a large-scale single-cell transcriptome atlas.

To investigate the immune response and mechanisms associated with severe coronavirus disease 2019 (COVID-19), we performed single-cell RNA sequencing on nasopharyngeal and bronchial samples from 19 clinically well-characterized patients with moderate or critical disease and from five healthy controls. We identified airway epithelial cell types and states vulnerable to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In patients with COVID-19, epithelial cells showed an average three-fold increase in expression of the SARS-CoV-2 entry receptor ACE2, which correlated with interferon signals by immune cells. Compared to moderate cases, critical cases exhibited stronger interactions between epithelial and immune cells, as indicated by ligand-receptor expression profiles, and activated immune cells, including inflammatory macrophages expressing CCL2, CCL3, CCL20, CXCL1, CXCL3, CXCL10, IL8, IL1B and TNF. The transcriptional differences in critical cases compared to moderate cases likely contribute to clinical observations of heightened inflammatory tissue damage, lung injury and respiratory failure. Our data suggest that pharmacologic inhibition of the CCR1 and/or CCR5 pathways might suppress immune hyperactivation in critical COVID-19.

COVID-19 severity correlates with airway epithelium-immune cell interactions identified by single-cell analysis.

The authors generated single-cell atlases of 23 lung, 16 kidney, 15 liver and 18 heart COVID-19 autopsy donor tissue samples, and spatial atlases of 14 lung donors.

COVID-19 tissue atlases reveal SARS-CoV-2 pathology and cellular targets.

Human organoids recapitulating the cell-type diversity and function of their target organ are valuable for basic and translational research. We developed light-sensitive human retinal organoids with multiple nuclear and synaptic layers and functional synapses. We sequenced the RNA of 285,441 single cells from these organoids at seven developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable "developed" state at a rate similar to human retina development in vivo. Transcriptomes of organoid cell types converged toward the transcriptomes of adult peripheral retinal cell types. Expression of disease-associated genes was cell-type-specific in adult retina, and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in human retinas.

Cell Types of the Human Retina and Its Organoids at Single-Cell Resolution

Common genetic variants confer substantial risk for chronic lung diseases, including pulmonary fibrosis (PF). Defining the genetic control of gene expression in a cell-type-specific and context-dependent manner is critical for understanding the mechanisms through which genetic variation influences complex traits and disease pathobiology. To this end, we performed single-cell RNA-sequencing of lung tissue from 67 PF and 49 unaffected donors. Employing a pseudo-bulk approach, we mapped expression quantitative trait loci (eQTL) across 38 cell types, observing both shared and cell type-specific regulatory effects. Further, we identified disease-interaction eQTL and demonstrated that this class of associations is more likely to be cell-type specific and linked to cellular dysregulation in PF. Finally, we connected PF risk variants to their regulatory targets in disease-relevant cell types. These results indicate that cellular context determines the impact of genetic variation on gene expression, and implicates context-specific eQTL as key regulators of lung homeostasis and disease.

Cell type-specific and disease-associated eQTL in the human lung

Some patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop severe pneumonia and acute respiratory distress syndrome1 (ARDS). Distinct clinical features in these patients have led to speculation that the immune response to virus in the SARS-CoV-2-infected alveolus differs from that in other types of pneumonia2. Here we investigate SARS-CoV-2 pathobiology by characterizing the immune response in the alveoli of patients infected with the virus. We collected bronchoalveolar lavage fluid samples from 88 patients with SARS-CoV-2-induced respiratory failure and 211 patients with known or suspected pneumonia from other pathogens, and analysed them using flow cytometry and bulk transcriptomic profiling. We performed single-cell RNA sequencing on 10 bronchoalveolar lavage fluid samples collected from patients with severe coronavirus disease 2019 (COVID-19) within 48 h of intubation. In the majority of patients with SARS-CoV-2 infection, the alveolar space was persistently enriched in T cells and monocytes. Bulk and single-cell transcriptomic profiling suggested that SARS-CoV-2 infects alveolar macrophages, which in turn respond by producing T cell chemoattractants. These T cells produce interferon-γ to induce inflammatory cytokine release from alveolar macrophages and further promote T cell activation. Collectively, our results suggest that SARS-CoV-2 causes a slowly unfolding, spatially limited alveolitis in which alveolar macrophages containing SARS-CoV-2 and T cells form a positive feedback loop that drives persistent alveolar inflammation.

Circuits between infected macrophages and T cells in SARS-CoV-2 pneumonia.

Collagen-producing cells maintain the complex architecture of the lung and drive pathologic scarring in pulmonary fibrosis. Here we perform single-cell RNA-sequencing to identify all collagen-producing cells in normal and fibrotic lungs. We characterize multiple collagen-producing subpopulations with distinct anatomical localizations in different compartments of murine lungs. One subpopulation, characterized by expression of Cthrc1 (collagen triple helix repeat containing 1), emerges in fibrotic lungs and expresses the highest levels of collagens. Single-cell RNA-sequencing of human lungs, including those from idiopathic pulmonary fibrosis and scleroderma patients, demonstrate similar heterogeneity and CTHRC1-expressing fibroblasts present uniquely in fibrotic lungs. Immunostaining and in situ hybridization show that these cells are concentrated within fibroblastic foci. We purify collagen-producing subpopulations and find disease-relevant phenotypes of Cthrc1-expressing fibroblasts in in vitro and adoptive transfer experiments. Our atlas of collagen-producing cells provides a roadmap for studying the roles of these unique populations in homeostasis and pathologic fibrosis.

Collagen-producing lung cell atlas identifies multiple subsets with distinct localization and relevance to fibrosis

Single-cell RNA sequencing was used to determine the cell type composition of all major human organs and construct a basic scheme for the human cell landscape (HCL).

Construction of A Human Cell Landscape by Single-cell mRNA-seq

Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. Here, we surveyed the immune compartment of 15 tissues of six deceased adult donors by single-cell RNA sequencing and paired VDJ sequencing. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of 45 finely phenotyped immune cell types and states, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. In summary, our multi-tissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis and antigen receptor sequencing.

Cross-tissue immune cell analysis reveals tissue-specific features in humans

Single-cell RNA sequencing was applied to identify distinct and dynamic cell populations, including an in-depth analysis of the fibroblast population, in lung fibrosis.

Defining the Activated Fibroblast Population in Lung Fibrosis Using Single Cell Sequencing.

Human pluripotent stem cell (hPSC)-derived intestinal organoids (HIOs) lack some cellular populations found in the native organ, including vasculature. Using single-cell RNA sequencing (scRNA-seq), we have identified a population of endothelial cells (ECs) present early in HIO differentiation that declines over time in culture. Here, we developed a method to expand and maintain this endogenous population of ECs within HIOs (vHIOs). Given that ECs possess organ-specific gene expression, morphology, and function, we used bulk RNA-seq and scRNA-seq to interrogate the developing human intestine, lung, and kidney in order to identify organ-enriched EC gene signatures. By comparing these gene signatures and validated markers to HIO ECs, we find that HIO ECs grown in vitro share the highest similarity with native intestinal ECs relative to kidney and lung. Together, these data demonstrate that HIOs can co-differentiate a native EC population that is properly patterned with an intestine-specific EC transcriptional signature in vitro.

Differentiation of Human Intestinal Organoids with Endogenous Vascular Endothelial Cells

To study the effect of cigarette smoke exposure on Sars-Cov2 infection, we directly exposed mucociliary air-liquid interface (ALI) cultures derived from primary human nonsmoker airway basal stem cells (ABSCs) to short term cigarette smoke and infected them with live SARS-CoV-2. We set out to examine the underlying mechanisms governing the increased susceptibility of cigarette smoke exposed ALI cultures to SARS-CoV-2 infection by usingle cell profiling of the cultures, which showed that interferon response genes were induced in SARS-CoV-2 infected airway epithelial cells in ALI cultures but smoking exposure together with SARS-CoV-2 infection reduced the interferon response.

Direct exposure to SARS-CoV-2 and cigarette smoke increases infection severity and alters the stem cell-derived airway repair response

How the innate and adaptive host immune system miscommunicate to worsen COVID-19 immunopathology has not been fully elucidated. Here, we perform single-cell deep-immune profiling of bronchoalveolar lavage (BAL) samples from 5 patients with mild and 26 with critical COVID-19 in comparison to BALs from non-COVID-19 pneumonia and normal lung. We use pseudotime inference to build T-cell and monocyte-to-macrophage trajectories and model gene expression changes along them. In mild COVID-19, CD8+ resident-memory (TRM) and CD4+ T-helper-17 (TH17) cells undergo active (presumably antigen-driven) expansion towards the end of the trajectory, and are characterized by good effector functions, while in critical COVID-19 they remain more naïve. Vice versa, CD4+ T-cells with T-helper-1 characteristics (TH1-like) and CD8+ T-cells expressing exhaustion markers (TEX-like) are enriched halfway their trajectories in mild COVID-19, where they also exhibit good effector functions, while in critical COVID-19 they show evidence of inflammation-associated stress at the end of their trajectories. Monocyte-to-macrophage trajectories show that chronic hyperinflammatory monocytes are enriched in critical COVID-19, while alveolar macrophages, otherwise characterized by anti-inflammatory and antigen-presenting characteristics, are depleted. In critical COVID-19, monocytes contribute to an ATP-purinergic signaling-inflammasome footprint that could enable COVID-19 associated fibrosis and worsen disease-severity. Finally, viral RNA-tracking reveals infected lung epithelial cells, and a significant proportion of neutrophils and macrophages that are involved in viral clearance.

Discriminating mild from critical COVID-19 by innate and adaptive immune single-cell profiling of bronchoalveolar lavages

Cigarette smoke first interacts with the lung through the cellularly diverse airway epithelium and goes on to drive development of most chronic lung diseases. Here, through single cell RNA-sequencing analysis of the tracheal epithelium from smokers and nonsmokers, we generate a comprehensive atlas of epithelial cell types and states, connect these into lineages, and define cell-specific responses to smoking. Our analysis infers multi-state lineages that develop into surface mucus secretory and ciliated cells and then contrasts these to the unique specification of submucosal gland (SMG) cells. Accompanying knockout studies reveal that tuft-like cells are the likely progenitor of both pulmonary neuroendocrine cells and CFTR-rich ionocytes. Our smoking analysis finds that all cell types, including protected stem and SMG populations, are affected by smoking through both pan-epithelial smoking response networks and hundreds of cell-specific response genes, redefining the penetrance and cellular specificity of smoking effects on the human airway epithelium. Overall design: For the in vivo dataset, we sequenced a total of 68,370 (36,248 after QC) epithelial cells from across 15 human tracheal donors (6 heavy smokers, 6 never-smokers, 2 light smokers, and 1 pediatric subject). For the in vitro dataset we sequenced a total of 8,722 (5,976 after QC) epithelial cells sampled from 20 time points along the differentiation process taken by air-liquid interface (ALI) cultures seeded from primary basal cells of 3 human tracheal donors (from ALI seed day to day 32 post-airlift)

Dissecting the cellular specificity of smoking effects and reconstructing lineages in the human airway epithelium

Melanoma brain metastasis (MBM) frequently occurs in patients with advanced melanoma; yet, our understanding of the underlying salient biology is rudimentary. Here, we performed single-cell/nucleus RNA-seq in 22 treatment-naive MBMs and 10 extracranial melanoma metastases (ECMs) and matched spatial single-cell transcriptomics and T cell receptor (TCR)-seq. Cancer cells from MBM were more chromosomally unstable, adopted a neuronal-like cell state, and enriched for spatially variably expressed metabolic pathways. Key observations were validated in independent patient cohorts, patient-derived MBM/ECM xenograft models, RNA/ATAC-seq, proteomics, and multiplexed imaging. Integrated spatial analyses revealed distinct geography of putative cancer immune evasion and evidence for more abundant intra-tumoral B to plasma cell differentiation in lymphoid aggregates in MBM. MBM harbored larger fractions of monocyte-derived macrophages and dysfunctional TOX+CD8+ T cells with distinct expression of immune checkpoints. This work provides comprehensive insights into MBM biology and serves as a foundational resource for further discovery and therapeutic exploration.

Dissecting the treatment-naive ecosystem of human melanoma brain metastasis.

Aberrant tissue-immune interactions are the hallmark of diverse chronic lung diseases. Here, we sought to define these interactions in emphysema, a progressive disease characterized by infectious exacerbations and loss of alveolar epithelium. Single-cell analysis of human emphysema lungs revealed the expansion of tissue-resident lymphocytes (TRLs). Murine studies identified a stromal niche for TRLs that expresses Hhip, a disease-variant gene downregulated in emphysema. Stromal-specific deletion of Hhip induced the topographic expansion of TRLs in the lung that was mediated by a hyperactive hedgehog-IL-7 axis. 3D immune-stem cell organoids and animal models of viral exacerbations demonstrated that expanded TRLs suppressed alveolar stem cell growth through interferon gamma (IFNγ). Finally, we uncovered an IFNγ-sensitive subset of human alveolar stem cells that was preferentially lost in emphysema. Thus, we delineate a stromal-lymphocyte-epithelial stem cell axis in the lung that is modified by a disease-variant gene and confers host susceptibility to emphysema.

Dysregulated lung stroma drives emphysema exacerbation by potentiating resident lymphocytes to suppress an epithelial stem cell reservoir

The human lung differs substantially from its mouse counterpart, resulting in a distinct distal airway architecture affected by disease pathology in chronic obstructive pulmonary disease. In humans, the distal branches of the airway interweave with the alveolar gas-exchange niche, forming an anatomical structure known as the respiratory bronchioles. Owing to the lack of a counterpart in mouse, the cellular and molecular mechanisms that govern respiratory bronchioles in the human lung remain uncharacterized. Here we show that human respiratory bronchioles contain a unique secretory cell population that is distinct from cells in larger proximal airways. Organoid modelling reveals that these respiratory airway secretory (RAS) cells act as unidirectional progenitors for alveolar type 2 cells, which are essential for maintaining and regenerating the alveolar niche. RAS cell lineage differentiation into alveolar type 2 cells is regulated by Notch and Wnt signalling. In chronic obstructive pulmonary disease, RAS cells are altered transcriptionally, corresponding to abnormal alveolar type 2 cell states, which are associated with smoking exposure in both humans and ferrets. These data identify a distinct progenitor in a region of the human lung that is not found in mouse that has a critical role in maintaining the gas-exchange compartment and is altered in chronic lung disease.

Human distal airways contain a multipotent secretory cell that can regenerate alveoli

Mapping the spatial distribution and molecular identity of constituent cells is essential for understanding tissue dynamics in health and disease. We lack a comprehensive map of human distal airways, including the terminal and respiratory bronchioles (TRBs), which are implicated in respiratory diseases. Here, using spatial transcriptomics and single-cell profiling of microdissected distal airways, we identify molecularly distinct TRB cell types that have not—to our knowledge—been previously characterized. These include airway-associated LGR5+ fibroblasts and TRB-specific alveolar type-0 (AT0) cells and TRB secretory cells (TRB-SCs). Connectome maps and organoid-based co-cultures reveal that LGR5+ fibroblasts form a signalling hub in the airway niche. AT0 cells and TRB-SCs are conserved in primates and emerge dynamically during human lung development. Using a non-human primate model of lung injury, together with human organoids and tissue specimens, we show that alveolar type-2 cells in regenerating lungs transiently acquire an AT0 state from which they can differentiate into either alveolar type-1 cells or TRB-SCs. This differentiation programme is distinct from that identified in the mouse lung. Our study also reveals mechanisms that drive the differentiation of the bipotent AT0 cell state into normal or pathological states. In sum, our findings revise human lung cell maps and lineage trajectories, and implicate an epithelial transitional state in primate lung regeneration and disease.

Human distal lung maps and lineage hierarchies reveal a bipotent progenitor

In coronavirus disease 2019 (COVID-19), hypertension and cardiovascular diseases are major risk factors for critical disease progression. However, the underlying causes and the effects of the main anti-hypertensive therapies—angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs)—remain unclear. Combining clinical data (n = 144) and single-cell sequencing data of airway samples (n = 48) with in vitro experiments, we observed a distinct inflammatory predisposition of immune cells in patients with hypertension that correlated with critical COVID-19 progression. ACEI treatment was associated with dampened COVID-19-related hyperinflammation and with increased cell intrinsic antiviral responses, whereas ARB treatment related to enhanced epithelial–immune cell interactions. Macrophages and neutrophils of patients with hypertension, in particular under ARB treatment, exhibited higher expression of the pro-inflammatory cytokines CCL3 and CCL4 and the chemokine receptor CCR1. Although the limited size of our cohort does not allow us to establish clinical efficacy, our data suggest that the clinical benefits of ACEI treatment in patients with COVID-19 who have hypertension warrant further investigation.

Hypertension delays viral clearance and exacerbates airway hyperinflammation in patients with COVID-19

Severe coronavirus disease 2019 (COVID-19) pneumonia survivors often exhibit long-term pulmonary sequelae, but the underlying mechanisms or associated local and systemic immune correlates are not known. Here, we have performed high-dimensional characterization of the pathophysiological and immune traits of aged COVID-19 convalescents, and correlated the local and systemic immune profiles with pulmonary function and lung imaging. We found that chronic lung impairment was accompanied by persistent respiratory immune alterations. We showed that functional severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–specific memory T and B cells were enriched at the site of infection compared with those of blood. Detailed evaluation of the lung immune compartment revealed that dysregulated respiratory CD8+ T cell responses were associated with the impaired lung function after acute COVID-19. Single-cell transcriptomic analysis identified the potential pathogenic subsets of respiratory CD8+ T cells contributing to persistent tissue conditions after COVID-19. Our results have revealed pathophysiological and immune traits that may support the development of lung sequelae after SARS-CoV-2 pneumonia in older individuals, with implications for the treatment of chronic COVID-19 symptoms.

Immune signatures underlying post-acute COVID-19 lung sequelae

Single-cell RNA sequencing (scRNA-Seq) provides a valuable platform for characterising multicellular ecosystems. Fibroblasts are a heterogeneous cell type involved in many physiological and pathological processes, but remain poorly-characterised. Analysis of fibroblasts is challenging: these cells are difficult to isolate from tissues, and are therefore commonly under-represented in scRNA-seq datasets. Here, we describe an optimised approach for fibroblast isolation from human lung tissues. We demonstrate the potential for this procedure in characterising stromal cell phenotypes using scRNA-Seq, analyse the effect of tissue disaggregation on gene expression, and optimise data processing to improve clustering quality. Overall design: mRNA profiles of human lung samples (tumour, inflamed and normal lung) from 3 patients.

Improving fibroblast characterization using single-cell RNA sequencing: an optimized tissue disaggregation and data processing pipeline.

Bud tip progenitor cells give rise to all murine lung epithelial lineages and have been described in the developing human lung; however, the mechanisms controlling human bud tip differentiation into specific lineages are unclear. Here, we used homogeneous human bud tip organoid cultures and identified SMAD signaling as a key regulator of the bud tip-to-airway transition. SMAD induction led to the differentiation of airway-like organoids possessing functional basal cells capable of clonal expansion and multilineage differentiation. To benchmark in vitro-derived organoids, we developed a single-cell mRNA sequencing atlas of the human lung from 11.5 to 21 weeks of development, which revealed high degrees of similarity between the in vitro-derived and in vivo airway. Together, this work sheds light on human airway differentiation in vitro and provides a single-cell atlas of the developing human lung.

In Vitro and In Vivo Development of the Human Airway at Single-Cell Resolution

The correspondence of cell state changes in diseased organs to peripheral protein signatures is currently unknown. Here, we generated and integrated single‐cell transcriptomic and proteomic data from multiple large pulmonary fibrosis patient cohorts. Integration of 233,638 single‐cell transcriptomes (n = 61) across three independent cohorts enabled us to derive shifts in cell type proportions and a robust core set of genes altered in lung fibrosis for 45 cell types. Mass spectrometry analysis of lung lavage fluid (n = 124) and plasma (n = 141) proteomes identified distinct protein signatures correlated with diagnosis, lung function, and injury status. A novel SSTR2+ pericyte state correlated with disease severity and was reflected in lavage fluid by increased levels of the complement regulatory factor CFHR1. We further discovered CRTAC1 as a biomarker of alveolar type‐2 epithelial cell health status in lavage fluid and plasma. Using cross‐modal analysis and machine learning, we identified the cellular source of biomarkers and demonstrated that information transfer between modalities correctly predicts disease status, suggesting feasibility of clinical cell state monitoring through longitudinal sampling of body fluid proteomes.

Integrative analysis of cell state changes in lung fibrosis with peripheral protein biomarkers

Here we describe sci-CAR, a combinatorial indexing strategy to jointly profile chromatin accessibility and mRNA in each of thousands of single cells. As a proof-of-concept, we apply sci-CAR to 4,825 cells comprising a time-series of dexamethasone treatment, as well as to 11,233 cells from the mouse kidney.

Joint profiling of chromatin accessibility and gene expression in thousands of single cells

While a substantial proportion of adults infected with SARS-CoV-2 progress to develop severe disease, children rarely manifest respiratory complications. Therefore, understanding differences in the local and systemic response to SARS-CoV-2 infection between children and adults may provide important clues about the pathogenesis of SARS-CoV-2 infection. To address this, we first generated a healthy reference multi-omics single cell data set from children (n=30) in whom we have profiled triple matched samples: nasal and tracheal brushings and PBMCs, where we track the developmental changes for 42 airway and 31 blood cell populations from infancy, through childhood to adolescence. This has revealed the presence of naive B and T lymphocytes in neonates and infants with a unique gene expression signature bearing hallmarks of innate immunity. We then contrast the healthy reference with equivalent data from severe paediatric and adult COVID-19 patients (total n=27), from the same three types of samples: upper and lower airways and blood. We found striking differences: children with COVID-19 as opposed to adults had a higher proportion of innate lymphoid and non-clonally expanded naive T cells in peripheral blood, and a limited interferon-response signature. In the airway epithelium, we found the highest viral load in goblet and ciliated cells and describe a novel inflammatory epithelial cell population. These cells represent a transitional regenerative state between secretory and ciliated cells; they were found in healthy children and were enriched in paediatric and adult COVID-19 patients. Epithelial cells display an antiviral and neutrophil-recruiting gene signature that is weaker in severe paediatric versus adult COVID-19. Our matched blood and airway samples allowed us to study the spatial dynamics of infection. Lastly, we provide a user-friendly interface for this data 1 as a highly granular reference for the study of immune responses in airways and blood in children.

Local and systemic responses to SARS-CoV-2 infection in children and adults

Lung transplantation can potentially be a life-saving treatment for patients with nonresolving COVID-19-associated respiratory failure. Concerns limiting lung transplantation include recurrence of SARS-CoV-2 infection in the allograft, technical challenges imposed by viral-mediated injury to the native lung, and the potential risk for allograft infection by pathogens causing ventilator-associated pneumonia in the native lung. Additionally, the native lung might recover, resulting in long-term outcomes preferable to those of transplant. Here, we report the results of lung transplantation in three patients with nonresolving COVID-19-associated respiratory failure. We performed single-molecule fluorescence in situ hybridization (smFISH) to detect both positive and negative strands of SARS-CoV-2 RNA in explanted lung tissue from the three patients and in additional control lung tissue samples. We conducted extracellular matrix imaging and single-cell RNA sequencing on explanted lung tissue from the three patients who underwent transplantation and on warm postmortem lung biopsies from two patients who had died from COVID-19-associated pneumonia. Lungs from these five patients with prolonged COVID-19 disease were free of SARS-CoV-2 as detected by smFISH, but pathology showed extensive evidence of injury and fibrosis that resembled end-stage pulmonary fibrosis. Using machine learning, we compared single-cell RNA sequencing data from the lungs of patients with late-stage COVID-19 to that from the lungs of patients with pulmonary fibrosis and identified similarities in gene expression across cell lineages. Our findings suggest that some patients with severe COVID-19 develop fibrotic lung disease for which lung transplantation is their only option for survival.

Lung transplantation for patients with severe COVID-19

Cancer cells are embedded in the tumor microenvironment (TME), a complex ecosystem of stromal cells. Here, we present a 52,698-cell catalog of the TME transcriptome in human lung tumors at single-cell resolution, validated in independent samples where 40,250 additional cells were sequenced. By comparing with matching non-malignant lung samples, we reveal a highly complex TME that profoundly molds stromal cells. We identify 52 stromal cell subtypes, including novel subpopulations in cell types hitherto considered to be homogeneous, as well as transcription factors underlying their heterogeneity. For instance, we discover fibroblasts expressing different collagen sets, endothelial cells downregulating immune cell homing and genes coregulated with established immune checkpoint transcripts and correlating with T-cell activity. By assessing marker genes for these cell subtypes in bulk RNA-sequencing data from 1,572 patients, we illustrate how these correlate with survival, while immunohistochemistry for selected markers validates them as separate cellular entities in an independent series of lung tumors. Hence, in providing a comprehensive catalog of stromal cells types and by characterizing their phenotype and co-optive behavior, this resource provides deeper insights into lung cancer biology that will be helpful in advancing lung cancer diagnosis and therapy.

Phenotype molding of stromal cells in the lung tumor microenvironment

We investigated IPF pathogenesis using single-cell RNA-sequencing of fresh lung explants, comparing human IPF fibrotic lower lobes reflecting late disease, upper lobes reflecting early disease and normal lungs. IPF lower lobes showed increased fibroblasts, and basal, ciliated, goblet and club cells, but decreased alveolar epithelial cells, and marked alterations in inflammatory cells. We found three discrete macrophage subpopulations in normal and fibrotic lungs, one expressing monocyte markers, one highly expressing FABP4 and INHBA (FABP4hi), and one highly expressing SPP1 and MERTK (SPP1hi). SPP1hi macrophages in fibrotic lower lobes showed highly upregulated SPP1 and MERTK expression. Low-level local proliferation of SPP1hi macrophages in normal lungs was strikingly increased in IPF lungs. Co-localisation and causal modelling supported the role for these highly proliferative SPP1hi macrophages in activation of IPF myofibroblasts in lung fibrosis. These data suggest that SPP1hi macrophages contribute importantly to lung fibrosis in IPF, and that therapeutic strategies targeting MERTK and macrophage proliferation may show promise for treatment of this disease.

Proliferating SPP1/MERTK-expressing macrophages in idiopathic pulmonary fibrosis

Developmental processes underlying normal tissue regeneration have been implicated in cancer, but the degree of their enactment during tumor progression and under the selective pressures of immune surveillance, remain unknown. Here we show that human primary lung adenocarcinomas are characterized by the emergence of regenerative cell types, typically seen in response to lung injury, and by striking infidelity among transcription factors specifying most alveolar and bronchial epithelial lineages. In contrast, metastases are enriched for key endoderm and lung-specifying transcription factors, SOX2 and SOX9, and recapitulate more primitive transcriptional programs spanning stem-like to regenerative pulmonary epithelial progenitor states. This developmental continuum mirrors the progressive stages of spontaneous outbreak from metastatic dormancy in a mouse model and exhibits SOX9-dependent resistance to natural killer cells. Loss of developmental stage-specific constraint in macrometastases triggered by natural killer cell depletion suggests a dynamic interplay between developmental plasticity and immune-mediated pruning during metastasis.

Regenerative lineages and immune-mediated pruning in lung cancer metastasis

There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2) which causes the disease COVID-19. SARS-CoV-2 spike (S)-protein binds ACE2, and in concert with host proteases, principally TMPRSS2, promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues, and the factors that regulate ACE2 expression, remain unknown. Here, we leverage human and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 amongst tissue-resident cell subsets. Overall design: Samples from 8 datasets are included: single-cell RNA-Seq studies: 2 human adult donors of inferior turbinate scrapings with two replicates each. Four mouse donors of nasal epithelial cells, two stimulated with IFNA and two controls with two replicates from each animal. 13 human ileal small intestine donors. 8 human lung tissue donors with mTB infection, mTB infection and HIV, or no mTB infection. Bulk RNA-seq samples: Two human donors stimulated with three replicates of each stimulation with IFNA, IFNG, IL17A, or IL4, each at increasing doses (0, 0.1 ,0.5, 1, 2, 5, 10 ng/mL) and 12 replicates of unstimulated samples. One mouse donor of cells from the trachea with three replicates of each stimulation with IFNA, IFNB, or IFNG, each at increasing doses (0, 0.1 ,0.5, 1, 2, 5, 10 ng/mL) and 12 replicates of unstimulated samples. One human cell line stimulated with three replicates of each stimulation with IFNA, IFNG, IL17A, or IL4, each at increasing doses (0, 0.1 ,0.5, 1, 2, 5, 10 ng/mL) and 12 replicates of unstimulated samples.

SARS-CoV-2 receptor ACE2 is an interferon-stimulated gene in human airway epithelial cells and is detected in specific cell subsets across tissues.

The SARS-CoV-2 pandemic affecting the human respiratory system severely challenges public health and urgently demands for increasing our understanding of COVID-19 pathogenesis, especially host factors facilitating virus infection and replication. SARS-CoV-2 was reported to enter cells via binding to ACE2, followed by its priming by TMPRSS2. Here, we investigate ACE2 and TMPRSS2 expression levels and their distribution across cell types in lung tissue (twelve donors, 39,778 cells) and in cells derived from subsegmental bronchial branches (four donors, 17,521 cells) by single nuclei and single cell RNA sequencing, respectively. While TMPRSS2 is expressed in both tissues, in the subsegmental bronchial branches ACE2 is predominantly expressed in a transient secretory cell type. Interestingly, these transiently differentiating cells show an enrichment for pathways related to RHO GTPase function and viral processes suggesting increased vulnerability for SARS-CoV-2 infection. Our data provide a rich resource for future investigations of COVID-19 infection and pathogenesis.

SARS‐CoV‐2 receptor ACE2 and TMPRSS2 are primarily expressed in bronchial transient secretory cells

Single Cell RNAseq of primary pulmonary endothelial cells.

Single cell lung suspensions of explanted healthy and IPF donor lung tissue were generated. scRNA-seq was performed on EPCAM negative live cells sorted by FACS. Puried mesenchymal cells were clustered to evaluate the mesenchymal cell sub-clusters Overall design: To investigate pulmonary fibroblast lineage and the subtypes in human healthy and IPF lungs, mesenchymal cells (EPCAM/CD31/CD45-) were collected from five lungs from healthy donors and five lungs from IPF patients, single cell RNA-sequencing was performed on the purified mesenchymal cells.

Single cell RNA-sequencing on healthy and IPF lung mesenchymal cells.

Lymphangioleiomyomatosis (LAM) is a metastasizing neoplasm of reproductive age women which causes cystic lung remodeling and progressive respiratory failure. While LAM lesions are known to contain abnormal smooth muscle-like cells which harbor mTOR activating mutations in TSC1 or TSC2, the tissue origins of the mutant “LAM cells” that invade the lung remain unclear. By employing single cell and single nuclear RNA sequencing on explanted LAM lungs, we identified a unique population of cells and associated signature genes and gene networks which were readily distinguished from those of endogenous lung cells. These unique LAMCORE cells shared closest transcriptomic similarity to normal uterus and share transcriptomic features with neural crest, as identified in uterine LAM lesions by single nuclear RNA-seq. Immunofluorescence microscopy demonstrated the expression of LAMCORE cell signature genes within LAM lesions in both lung and uterus. Serum aptamer proteomics and ELISA identified biomarkers consistent with the signature genes expressed and predicted to be secreted by LAMCORE cells. Single cell transcriptomics strongly supports a uterine neural crest origin of LAMCORE cells; providing insights into disease pathogenesis and informing future treatment strategies for LAM. Overall design: scRNA-seq and snRNA-seq was performed using the 10x Chromium platform on four lung explants from LAM patients undergoing lung transplantation. We also performed scRNA-seq on a renal AML resected from a patient with a sporadic AML (S-AML), and snRNA-seq on uterine tissue obtained at hysterectomy from an S-LAM patient. As controls, we conducted scRNA-seq on a 31 years old female explanted lung, brain dead, beating-heart, organ donor and snRNA-seq on one normal uterine tissue at hysterectomy from a 29 years old female patient with cervical cancer, and obtained scRNA-seq data of six additional female donor lungs from Gene Expression Omnibus (GSE122960) and scRNA-seq data from normal mouse uterus (GSE118180). qRT-PCR, immunofluorescence and immunochemical stains to validate the spatial relationships of LAM cells and LAMCORE signature genes.Serum aptamer proteomics and ELISA assays screening were used for validation of secretome predictions.

Single-Cell Transcriptomic Analysis Identifies a Unique Pulmonary Lymphangioleiomyomatosis Cell

Rationale: The contributions of diverse cell populations in the human lung to pulmonary fibrosis pathogenesis are poorly understood. Single-cell RNA sequencing can reveal changes within individual cell populations during pulmonary fibrosis that are important for disease pathogenesis. Objectives: To determine whether single-cell RNA sequencing can reveal disease-related heterogeneity within alveolar macrophages, epithelial cells, or other cell types in lung tissue from subjects with pulmonary fibrosis compared with control subjects. Methods: We performed single-cell RNA sequencing on lung tissue obtained from eight transplant donors and eight recipients with pulmonary fibrosis and on one bronchoscopic cryobiospy sample from a patient with idiopathic pulmonary fibrosis. We validated these data using in situ RNA hybridization, immunohistochemistry, and bulk RNA-sequencing on flow-sorted cells from 22 additional subjects. Measurements and Main Results: We identified a distinct, novel population of profibrotic alveolar macrophages exclusively in patients with fibrosis. Within epithelial cells, the expression of genes involved in Wnt secretion and response was restricted to nonoverlapping cells. We identified rare cell populations including airway stem cells and senescent cells emerging during pulmonary fibrosis. We developed a web-based tool to explore these data. Conclusions: We generated a single-cell atlas of pulmonary fibrosis. Using this atlas, we demonstrated heterogeneity within alveolar macrophages and epithelial cells from subjects with pulmonary fibrosis. These results support the feasibility of discovery-based approaches using next-generation sequencing technologies to identify signaling pathways for targeting in the development of personalized therapies for patients with pulmonary fibrosis.

Single-Cell Transcriptomic Analysis of Human Lung Provides Insights into the Pathobiology of Pulmonary Fibrosis.

Advanced metastatic cancer poses utmost clinical challenges and may present molecular and cellular features distinct from an early-stage cancer. Herein, we present single-cell transcriptome profiling of metastatic lung adenocarcinoma, the most prevalent histological lung cancer type diagnosed at stage IV in over 40% of all cases. From 208,506 cells populating the normal tissues or early to metastatic stage cancer in 44 patients, we identify a cancer cell subtype deviating from the normal differentiation trajectory and dominating the metastatic stage. In all stages, the stromal and immune cell dynamics reveal ontological and functional changes that create a pro-tumoral and immunosuppressive microenvironment. Normal resident myeloid cell populations are gradually replaced with monocyte-derived macrophages and dendritic cells, along with T-cell exhaustion. This extensive single-cell analysis enhances our understanding of molecular and cellular dynamics in metastatic lung cancer and reveals potential diagnostic and therapeutic targets in cancer-microenvironment interactions.

Single-cell RNA sequencing demonstrates the molecular and cellular reprogramming of metastatic lung adenocarcinoma

Pulmonary fibrosis (PF) is a form of chronic lung disease characterized by progressive destruction of normal alveolar gas-exchange surfaces and accumulation of extracellular matrix (ECM). In order to comprehensively define the cell types, mechanisms and mediators driving ECM deposition and fibrotic remodeling in lungs with pulmonary fibrosis, we performed single-cell RNA-sequencing (scRNA-seq) of single-cell suspensions generated from non-fibrotic control and PF lungs. Analysis of over 114,000 cells from 20 PF and 10 control lungs identified 31 distinct cell types. We identified multiple distinct lineages directly contribute to ECM expansion, including a novel HAS1hi fibroblast subtype and a previously undescribed KRT5-/KRT17+, collagen and ECM-producing epithelial cell population that was highly enriched in PF lungs. Together these data provide high-resolution insights into the basic mechanisms of pulmonary fibrosis, and indicate a direct profibrotic role of the lung epithelium in PF pathogenesis. Overall design: We performed single-cell RNA-sequencing (scRNA-seq) of single-cell suspensions generated from non-fibrotic control and pulmonary fibrosis (PF) lungs

Single-cell RNA sequencing reveals profibrotic roles of distinct epithelial and mesenchymal lineages in pulmonary fibrosis

We provide a single cell atlas of Idiopathic Pulmonary Fibrosis (IPF), a fatal interstitial lung disease, focusing on resident lung cell populations. By profiling 312,928 cells from 32 IPF, 29 healthy control and 18 chronic obstructive pulmonary disease (COPD) lungs, we demonstrate that IPF is characterized by changes in discrete subpopulations of cells in the three major parenchymal compartments: the epithelium, endothelium and stroma. Among epithelial cells, we identify a novel population of IPF enriched aberrant basaloid cells that co-express basal epithelial markers, mesenchymal markers, senescence markers, developmental transcription factors and are located at the edge of myofibroblast foci in the IPF lung. Among vascular endothelial cells in the in IPF lung parenchyma we identify an expanded cell population transcriptomically identical to vascular endothelial cells normally restricted to the bronchial circulation. We confirm the presence of both populations by immunohistochemistry and independent datasets. Among stromal cells we identify fibroblasts and myofibroblasts in both control and IPF lungs and leverage manifold-based algorithms diffusion maps and diffusion pseudotime to infer the origins of the activated IPF myofibroblast. Our work provides a comprehensive catalogue of the aberrant cellular transcriptional programs in IPF, demonstrates a new framework for analyzing complex disease with scRNAseq, and provides the largest lung disease single-cell atlas to date.

Single-cell RNA-seq reveals ectopic and aberrant lung-resident cell populations in idiopathic pulmonary fibrosis

Immunotherapy is a mainstay of non-small cell lung cancer (NSCLC) management. While tumor mutational burden (TMB) correlates with response to immunotherapy, little is known about the relationship between the baseline immune response and tumor genotype. Using single-cell RNA sequencing, we profiled 361,929 cells from 35 early-stage NSCLC lesions. We identified a cellular module consisting of PDCD1+CXCL13+ activated T cells, IgG+ plasma cells, and SPP1+ macrophages, referred to as the lung cancer activation module (LCAMhi). We confirmed LCAMhi enrichment in multiple NSCLC cohorts, and paired CITE-seq established an antibody panel to identify LCAMhi lesions. LCAM presence was found to be independent of overall immune cell content and correlated with TMB, cancer testis antigens, and TP53 mutations. High baseline LCAM scores correlated with enhanced NSCLC response to immunotherapy even in patients with above median TMB, suggesting that immune cell composition, while correlated with TMB, may be a nonredundant biomarker of response to immunotherapy.

Single-cell analysis of human non-small cell lung cancer lesions refines tumor classification and patient stratification

Objectives: Myofibroblasts are key effector cells in the extracellular matrix remodeling of systemic sclerosis-associated interstitial lung disease (SSc-ILD), however the diversity of fibroblast populations present in the healthy and SSc-ILD lung is unknown, and has prevented the specific study of the myofibroblast transcriptome. We sought to identify and define the transcriptomes of myofibroblasts and other mesenchymal cell populations in human healthy and SSc-ILD lungs to understand how alterations in fibroblast phenotypes lead to SSc-ILD fibrosis. Methods: We performed droplet-based single-cell RNA-sequencing with integrated canonical correlation analysis of 13 explanted lung tissue specimens (56,196 cells) from 4 healthy control and 4 SSc-ILD patients, with findings confirmed by cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) in additional samples. Results: Examination of gene expression in mesenchymal cells identified two major, SPINT2hiand MFAP5hi, and one minor, WIF1hi, fibroblast populations in the healthy control lung. Combined analysis of control and SSc-ILD mesenchymal cells identified SPINT2hi, MFAP5hi, few WIF1hi fibroblasts, and a new large myofibroblast population with evidence of actively proliferating myofibroblasts. We compared differential gene expression between all SSc-ILD and control mesenchymal cell populations, as well as amongst the fibroblast subpopulations, showing that myofibroblasts undergo the greatest phenotypic changes in SSc-ILD and strongly upregulate expression of collagens and other profibrotic genes. Conclusions: Our results demonstrate previously unrecognized fibroblast heterogeneity in SSc-ILD and healthy lungs, and define multimodal transcriptome-phenotypes associated with these populations. Our data indicate that myofibroblast differentiation and proliferation are key pathologic mechanisms driving fibrosis in SSc-ILD.

Single-cell analysis reveals fibroblast heterogeneity and myofibroblasts in systemic sclerosis-associated interstitial lung disease

Inflammation is a key driver of cystic fibrosis (CF) lung disease, not addressed by current standard care. Improved understanding of the mechanisms leading to aberrant inflammation may assist the development of effective anti-inflammatory therapy. Single-cell RNA sequencing (scRNA-seq) allows profiling of cell composition and function at previously unprecedented resolution. Herein, we seek to use multimodal single-cell analysis to comprehensively define immune cell phenotypes, proportions and functional characteristics in preschool children with CF. We analyzed 42,658 cells from bronchoalveolar lavage of 11 preschool children with CF and a healthy control using scRNA-seq and parallel assessment of 154 cell surface proteins. Validation of cell types identified by scRNA-seq was achieved by assessment of samples by spectral flow cytometry. Analysis of transcriptome expression and cell surface protein expression, combined with functional pathway analysis, revealed 41 immune and epithelial cell populations in BAL. Spectral flow cytometry analysis of over 256,000 cells from a subset of the same patients revealed high correlation in major cell type proportions across the two technologies. Macrophages consisted of 13 functionally distinct sub populations, including previously undescribed populations enriched for markers of vesicle production and regulatory/repair functions. Other novel cell populations included CD4 T cells expressing inflammatory IFNα/β and NFκB signalling genes. Our work provides a comprehensive cellular analysis of the pediatric lower airway in preschool children with CF, reveals novel cell types and provides a reference for investigation of inflammation in early life CF.

Single-cell atlas of bronchoalveolar lavage from preschool cystic fibrosis reveals new cell phenotypes

Efforts to decipher chronic lung disease and to reconstitute functional lung tissue through regenerative medicine have been hampered by an incomplete understanding of cell-cell interactions governing tissue homeostasis. Because the structure of mammalian lungs is highly conserved at the histologic level, we hypothesized that there are evolutionarily conserved homeostatic mechanisms that keep the fine architecture of the lung in balance. We have leveraged single-cell RNA sequencing techniques to identify conserved patterns of cell-cell cross-talk in adult mammalian lungs, analyzing mouse, rat, pig, and human pulmonary tissues. Specific stereotyped functional roles for each cell type in the distal lung are observed, with alveolar type I cells having a major role in the regulation of tissue homeostasis. This paper provides a systems-level portrait of signaling between alveolar cell populations. These methods may be applicable to other organs, providing a roadmap for identifying key pathways governing pathophysiology and informing regenerative efforts.

Single-cell connectomic analysis of adult mammalian lungs

The functions of innate lymphoid cells (ILCs) in immune system are increasingly appreciated, whereas the early development of ILCs in human remains elusive. In this study, we sorted humanhematopoietic stem progenitor cells, lymphoid progenitors, presumed ILC progenitor/precursors and mature ILCs in the fetal hematopoietic, lymphoid and non-lymphoid tissues, from 8 to 12 PCW,for single-cell RNA-sequencing, followed by computational analysis and functional validation. We delineated the early phase of ILC development, from hematopoietic stem progenitor cells to multipotent lymphoid progenitors and to ILC progenitors, which mainly occurred in fetal liver and intestine. We further unveiled interleukin-3 receptor alpha (IL-3RA) as the surface marker for the lymphoid progenitors with T cell, B cell and ILC potentials. Notably, we determined the heterogeneity and tissue distribution of each ILC subpopulation, revealing the shared proliferating characteristics of the precursors of each ILC subtype. Additionally, a novel unconventional ILC2 subpopulation (CRTH2-CCR9+ ILC2) was identified in fetal thymus. Taken together, our study illuminates the precise cellular and molecular features underlying the stepwise formation of human fetal ILC hierarchy with remarkable spatiotemporal heterogeneity. Overall design: Here, we provided an unprecedented single-cell transcriptome atlas of stepwise ILC ontogeny in early human fetus using cells from fetal hematopoietic, lymphoid and non-lymphoid tissues spanning 8 to 12 post-conception weeks (PCWs).

Single-cell deciphering of human fetal innate lymphoid cell development

While critical for host defense, innate immune cells are also pathologic drivers of acute respiratory distress syndrome (ARDS). Innate immune dynamics during COVID-19 ARDS, compared to ARDS from other respiratory pathogens, is unclear. Moreover, mechanisms underlying beneficial effects of dexamethasone during severe COVID-19 remain elusive. Using scRNA-seq and plasma proteomics, we discovered that compared to bacterial ARDS, COVID-19 was associated with expansion of distinct neutrophil states characterized by interferon (IFN) and prostaglandin (PG) signalling. Dexamethasone during severe COVID-19 depleted circulating neutrophils, altered IFNactive neutrophils, downregulated interferon-stimulated gene, and activated IL1R2+ve neutrophils. Dexamethasone also expanded immunosuppressive immature neutrophils and remodeled cellular interactions by changing neutrophils from information receivers into information providers. Male patients had higher proportions of IFNactive neutrophils, preferential steroid-induced immature neutrophil expansion, and possibly different effects on outcome. Our single-cell atlas (www.biernaskielab.ca/COVID_neutrophil) defines COVID-19-enriched neutrophil states and molecular mechanisms of dexamethasone action to develop targeted immunotherapies for severe COVID-19. Overall design: Leukocyte and lymphocyte preparation: For lymphocyte preparation, whole blood (2mL) was collected in 5mL polystyrene round-bottom tubes. Tubes were spun (15min, 3000rpm, Room Temperature [RT]) and plasma was removed. 100 microL of Isolation Cocktail and 100 microL of Rapid Spheres (Easy SepTM Direct Human Total Lymphocytes Isolation Kit: 19655, StemCell Technologies) were added to the remaining whole blood. After mixing and 5min incubation at RT, the sample volumes of ≤ 2.5mL blood were topped up to 5mL with D-PBS+2%FBS + 1mM EDTA. The diluted sample was incubated in the magnet without lid for 5min, at RT. This last step was repeated twice before cell resuspension in 5mL of PBS+0.04% BSA. After 2 washes in PBS+0.04% BSA, and centrifugation for 5 min at 2000rpm, 7500 lymphocytes were resuspended in 25 microL of PBS+0.04% BSA. For leukocytes preparation, whole blood was collected in heparin containing vacutubes and 12 microL of 0.5M EDTA with 1mL of PBS+2% FBS and 50 microL of RBC of EasySep RBC Depletion spheres (EasySepTM RBC Depletion Reagent: 18170, Stem Cell Technologies) were added. After 5 min of magnet incubation, at RT, tubes were inverted and poured into a new tube. 50 microL of RBC depletion spheres were added. 5 min after incubation on the magnet, the tube was inverted, and cell suspension was poured into a new 15mL tube. After 2 washes in 5mL of PBS+0.04% BSA and centrifugation at 2000rpm for 5 min at 20oC, cells were resuspended in 25 microL of PBS+0.04% BSA. Single-cell RNA-Seq library construction, alignment, and quality control: A total of 15,000 single cells (containing an equal proportion of leukocytes and lymphocytes) were loaded for partitioning using 10X Genomics NextGEM Gel Bead emulsions. All samples were processed as per manufacturer’s protocol. Quality control and pre-loading cDNA quantification was performed using TapeStation D1000 ScreenTape assay. Sequencing was performed using Illumina NovaSeq S2 and SP 100 cycle dual lane flow cells over multiple rounds to ensure each sample received approximately 32,000 reads per cell. Sequencing reads were aligned using CellRanger 3.1.0 pipeline29 to two sets of reference genomes: 1. standard pre-built GRCh38 human reference, and 2. a modified GRCh38 reference with two SARS-CoV-2 genomes (MT412228 and MN908947.3) appended. Since no SARS-CoV-2 reads were detected in whole blood single-cell samples30, all analyses presented in this manuscript were performed using standard pre-built GRCh38 reference. Samples that passed alignment QC were aggregated into single datasets using CellRanger aggr with between-sample normalization to ensure each sample received an equal number of mapped reads per cell. Aggregated non-dexamethasone-treated COVID-19 (n = 12) and bacterial ARDS (n = 9) samples recovered 1,872,659 cells that were sequenced to 38,410 post-normalization reads per cell. Likewise, aggregated COVID-19 samples with (n = 9) or without (n = 12) dexamethasone recovered 1,748,551 single cells sequenced to 51,415 post-normalization reads per cell. Processed data availability: Single-cell datasets can be further explored on our companion portal at http://biernaskielab.ca/COVID_neutrophil or http://biernaskielab.com/COVID_neutrophil. Velocyto-generated LOOM files and processed R objects are available for reanalysis from: http://doi.org/10.6084/m9.figshare.14330795. Whole blood bulk RNA-Seq datasets employed as an independent validation cohort were downloaded from GSE157103. BALF scRNA-Seq datasets from severe and moderate COVID-19 were downloaded from GSE145926. Processed BALF scRNA-Seq objects from patients with bacterial pneumonia and COVID-19 (archived at GSE167118) were downloaded from authors’ archive: https://figshare.com/articles/dataset/_/13608734. Mass spectrometry datasets are available via ProteomeXchange Consortium via the PRIDE partner repository with identifier PXD028429.

Single-cell landscape of bronchoalveolar immune cells in patients with COVID-19

Respiratory failure associated with COVID-19 has placed focus on the lungs. Here, we present single-nucleus accessible chromatin profiles of 90,980 nuclei and matched single-nucleus transcriptomes of 46,500 nuclei in non-diseased lungs from donors of ~30 weeks gestation,~3 years and ~30 years. We mapped candidate cis-regulatory elements (cCREs) and linked them to putative target genes. We identified distal cCREs with age-increased activity linked to SARS-CoV-2 host entry gene TMPRSS2 in alveolar type 2 cells, which had immune regulatory signatures and harbored variants associated with respiratory traits. At the 3p21.31 COVID-19 risk locus, a candidate variant overlapped a distal cCRE linked to SLC6A20, a gene expressed in alveolar cells and with known functional association with the SARS-CoV-2 receptor ACE2. Our findings provide insight into regulatory logic underlying genes implicated in COVID-19 in individual lung cell types across age. More broadly, these datasets will facilitate interpretation of risk loci for lung diseases.

Single-cell multiomic profiling of human lungs reveals cell-type-specific and age-dynamic control of SARS-CoV2 host genes

Background: As core units of organ tissues, cells of various types play their harmonious rhythms to maintain the homeostasis of the human body. It is essential to identify the characteristics of cells in human organs and their regulatory networks for understanding the biological mechanisms related to health and disease. However, a systematic and comprehensive single-cell transcriptional profile across multiple organs of a normal human adult is missing. Results: We perform single-cell transcriptomes of 84,363 cells derived from 15 tissue organs of one adult donor and generate an adult human cell atlas. The adult human cell atlas depicts 252 subtypes of cells, including major cell types such as T, B, myeloid, epithelial, and stromal cells, as well as novel COCH+ fibroblasts and FibSmo cells, each of which is distinguished by multiple marker genes and transcriptional profiles. These collectively contribute to the heterogeneity of major human organs. Moreover, T cell and B cell receptor repertoire comparisons and trajectory analyses reveal direct clonal sharing of T and B cells with various developmental states among different tissues. Furthermore, novel cell markers, transcription factors and ligand-receptor pairs are identified with potential functional regulations in maintaining the homeostasis of human cells among tissues. Conclusions: The adult human cell atlas reveals the inter- and intra-organ heterogeneity of cell characteristics and provides a useful resource in uncovering key events during the development of human diseases in the context of the heterogeneity of cells and organs. Overall design: We performed single-cell transcriptomes of 84,363 cells derived from 15 tissue organs of one adult donor and generated an adult human cell atlas (AHCA). Keywords: Human cell atlas, Single-cell RNA sequencing, TCR, BCR, Transcriptome

Single-cell transcriptome profiling of an adult human cell atlas of 15 major organs

Human T cells coordinate adaptive immunity in diverse anatomic compartments through production of cytokines and effector molecules, but it is unclear how tissue site influences T cell persistence and function. Here, we use single cell RNA-sequencing (scRNA-seq) to define the heterogeneity of human T cells isolated from lungs, lymph nodes, bone marrow and blood, and their functional responses following stimulation. Through analysis of >50,000 resting and activated T cells, we reveal tissue T cell signatures in mucosal and lymphoid sites, and lineage-specific activation states across all sites including distinct effector states for CD8+ T cells and an interferon-response state for CD4+ T cells. Comparing scRNA-seq profiles of tumor-associated T cells to our dataset reveals predominant activated CD8+ compared to CD4+ T cell states within multiple tumor types. Our results therefore establish a high dimensional reference map of human T cell activation in health for analyzing T cells in disease.

Single-cell transcriptomics of human T cells reveals tissue and activation signatures in health and disease

Understanding gene function and regulation in homeostasis and disease requires knowledge of the cellular and tissue contexts in which genes are expressed. Here, we applied four single-nucleus RNA sequencing methods to eight diverse, archived, frozen tissue types from 16 donors and 25 samples, generating a cross-tissue atlas of 209,126 nuclei profiles, which we integrated across tissues, donors, and laboratory methods with a conditional variational autoencoder. Using the resulting cross-tissue atlas, we highlight shared and tissue-specific features of tissue-resident cell populations; identify cell types that might contribute to neuromuscular, metabolic, and immune components of monogenic diseases and the biological processes involved in their pathology; and determine cell types and gene modules that might underlie disease mechanisms for complex traits analyzed by genome-wide association studies.

Single-nucleus cross-tissue molecular reference maps toward understanding disease gene function.

We have created a compendium of single cell transcriptome data from the model
organism Mus musculus comprising more than 100,000 cells from 20 organs and
tissues. These data represent a new resource for cell biology, revealing gene
expression in poorly characterized cell populations and allowing for direct and
controlled comparison of gene expression in cell types shared between tissues, such
as T-lymphocytes and endothelial cells from distinct anatomical locations. Two
distinct technical approaches were used for most tissues: one approach, microfluidic
droplet-based 3’-end counting, enabled the survey of thousands of cells at relatively
low coverage, while the other, FACS-based full length transcript analysis, enabled
characterization of cell types with high sensitivity and coverage. The cumulative
data provide the foundation for an atlas of transcriptomic cell biology.

Tabula Muris: Transcriptomic characterization of 20 organs and tissues from Mus musculus at single cell resolution

In recent years there has been tremendous progress towards deep molecular characterization of cell types using single cell transcriptome sequencing. Here we report a single cell transcriptomic atlas comprising nearly 500,000 cells from 24 different human tissues and organs. In several instances multiple organs were analyzed from the same donor. Analyzing organs from the same individual controls for genetic background, age, environment, and epigenetic effects, and enables a detailed comparison of cell types that are shared between tissues. This resource provides a rich molecular characterization of more than 400 cell types, their distribution across tissues, and detailed information about tissue specific variation in gene expression. We have used the fact that multiple tissues came from the same donor to study the clonal distribution of T cells between tissues, to understand the tissue specific mutation rate in B cells, and to analyze the cell cycle state and proliferative potential of shared cell types across tissues. Finally, we have also used this data to characterize cell type specific RNA splicing and how such splicing varies across tissues within an individual.

The Tabula Sapiens: A multiple-organ, single-cell transcriptomic atlas of humans

Type 2 alveolar epithelial cells (AEC2s) function as progenitor cells in the lung. We have shown previously that failure of AEC2 regeneration results in progressive lung fibrosis in mice and is a cardinal feature of idiopathic pulmonary fibrosis (IPF). In this study, we identified deficiency of a specific zinc transporter, SLC39A8 (ZIP8), in AEC2s from both IPF lungs and lungs of old mice. Loss of ZIP8 expression was associated with impaired renewal capacity of AEC2s and enhanced lung fibrosis. ZIP8 regulation of AEC2 progenitor function was dependent on SIRT1. Replenishment with exogenous zinc and SIRT1 activation promoted self-renewal and differentiation of AEC2s from lung tissues of IPF patients and old mice.

The ZIP8/SIRT1 axis regulates alveolar progenitor cell renewal in aging and idiopathic pulmonary fibrosis

Rhabdomyosarcoma (RMS) is the most soft tissue sarcoma of childhood and histologically mimics developing skeletal muscle. To better understand RMS, we performed single-cell RNA-seq of one embryonal subtype RMS (ERMS) and one alveolar subtype RMS (ARMS). We expanded our observations by performing single-nucleus RNA-seq of 18 patient tumors (12 ERMS, 6 ARMS). All 18 of these tumors were used to generate orthotopic patient-derived xenografts, and we performed single-cell RNA-seq of all 18 O-PDXs to compare heterogeneity between the original tumor and the patient-derived model. 15 of the O-PDXs underwent lentiviral barcoding, and lineage could be tracked using a separate dial-out PCR step during the single-cell RNA-seq workflow. We performed single-cell RNA-seq of an ex vivo organoid, showing that we can preserve heterogeneity in this model. We expanded our study to the epigenetic level by using single-cell ATAC-sequencing of 7 O-PDXs. Finally, we longitudinally tracked shifts in heterogeneity in an O-PDX model treated with chemotherapy. Overall design: We performed single-cell RNA-seq from 2 patient RMS tumors, 18 O-PDXs, and 1 organoid. Additionally, we performed single-nucleus RNA-seq from 18 patient RMS tumors and single-cell ATAC-seq from 7 O-PDXs. We also provide dialout PCR data from 15 RMS O-PDX that were used for lentiviral barcode experiments to track clonal lineages within O-PDXs.

The myogenesis program drives clonal selection and drug resistance in rhabdomyosarcoma

Single cell sequencing of human airway epithelium from normal and cystic fibrosis lungs

Transcriptional analysis of cystic fibrosis airways at single-cell resolution reveals altered epithelial cell states and composition

Assessment of the effect of cold ischaemic time on single cell RNAseq data from human tissues using 10x Genomics 3' single cell RNA sequencing. This project contains data for spleen, oesophagus epithelium and lung parenchyma, three tissues that had previously been reported to have differential sensitivity to ischaemia. Samples were collected into Hypothermasol FRS hypothermic preservation media and dissociated fresh (as soon as possible) or at 12h, 24h, 72h post onset of cold ischaemia in the donor. Single cell and bulk RNA sequencing data was generated at each time point and whole genome sequencing was carried out for each donor.

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