Human alveolar type 2 epithelium transdifferentiates into metaplastic KRT5+ basal cells

SUMMARYUnderstanding differential lineage potential of orthologous stem cells across species can shed light on human disease. Here, utilizing 3D organoids, single cell RNAseq, and xenotransplants, we demonstrate that human alveolar type 2 cells (hAEC2s), unlike murine AEC2s, are multipotent and able to transdifferentiate into KRT5+ basal cells when co-cultured with primary fibroblasts in 3D organoids. Trajectory analyses and immunophenotyping of epithelial progenitors in idiopathic pulmonary fibrosis (IPF) indicate that hAEC2s transdifferentiate into metaplastic basal cells through alveolar-basal intermediate (ABI) cells that we also identify in hAEC2-derived organoids. Modulating hAEC2-intrinsic and niche factors dysregulated in IPF can attenuate metaplastic basal cell transdifferentiation and preserve hAEC2 identity. Finally, hAEC2s transplanted into fibrotic immune-deficient murine lungs engraft as either hAEC2s or differentiated KRT5+ basal cells. Our study indicates that hAEC2s-loss and expansion of alveolar metaplastic basal cells in IPF are causally connected, which would not have been revealed utilizing murine AEC2s as a model.HighlightsHuman AEC2s transdifferentiate into KRT5+ basal cells when accompanied by primary adult human lung mesenchyme in 3D organoid culture.Alterations of hAEC2-intrinsic and niche factors dysregulated in IPF can modify metaplastic hAEC2 transdifferentiation.hAEC2s engraft into fibrotic lungs of immune-deficient mice and transdifferentiate into metaplastic basal cells.Transcriptional trajectory analysis suggests that hAEC2s in IPF gives rise to metaplastic basal cells via alveolar-basal intermediate cells.

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The aging transcriptome and cellular landscape of the human lung in relation to SARS-CoV-2

Nature Communications ◽

10.1038/s41467-020-20323-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ryan D. Chow ◽

Medha Majety ◽

Sidi Chen

Keyword(s):

Stress Responses ◽

Human Lung ◽

Airway Smooth Muscle Cells ◽

Alveolar Type ◽

Basal Cells ◽

Deconvolution Analysis ◽

Cellular Replication ◽

Older Populations

AbstractAge is a major risk factor for severe coronavirus disease-2019 (COVID-19). Here, we interrogate the transcriptional features and cellular landscape of the aging human lung. By intersecting these age-associated changes with experimental data on SARS-CoV-2, we identify several factors that may contribute to the heightened severity of COVID-19 in older populations. The aging lung is transcriptionally characterized by increased cell adhesion and stress responses, with reduced mitochondria and cellular replication. Deconvolution analysis reveals that the proportions of alveolar type 2 cells, proliferating basal cells, goblet cells, and proliferating natural killer/T cells decrease with age, whereas alveolar fibroblasts, pericytes, airway smooth muscle cells, endothelial cells and IGSF21+ dendritic cells increase with age. Several age-associated genes directly interact with the SARS-CoV-2 proteome. Age-associated genes are also dysregulated by SARS-CoV-2 infection in vitro and in patients with severe COVID-19. These analyses illuminate avenues for further studies on the relationship between age and COVID-19.

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Human alveolar Type 2 epithelium transdifferentiates into metaplastic KRT5+ basal cells during alveolar repair

10.1242/prelights.23417 ◽

2020 ◽

Author(s):

Julio Sainz de Aja

Keyword(s):

Alveolar Type ◽

Basal Cells

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Cryobanking of human distal lung epithelial cells for preservation of their phenotypic and functional characteristics.

10.1101/2021.11.15.468402 ◽

2021 ◽

Author(s):

Bindu Konda ◽

Apoorva Mulay ◽

Changfu Yao ◽

Edo Israely ◽

Stephen Beil ◽

...

Keyword(s):

Single Cell ◽

Lung Tissue ◽

Human Lung ◽

Alveolar Type ◽

Basal Cells ◽

Human Lung Tissue ◽

Downstream Analysis ◽

Long Term Preservation

The epithelium lining airspaces of the human lung is maintained by regional stem cells including basal cells of pseudostratified airways and alveolar type 2 pneumocytes (AT2) of the alveolar gas-exchange region. Despite effective methods for long-term preservation of airway basal cells, methods for efficient preservation of functional epithelial cell types of the distal gas-exchange region are lacking. Here we detail a method for cryobanking of epithelial cells from either mouse or human lung tissue for preservation of their phenotypic and functional characteristics. Flow cytometric profiling, epithelial organoid-forming efficiency, and single cell transcriptomic analysis, were used to compare cells recovered from cryopreserved tissue with those of freshly dissociated tissue. Alveolar type 2 cells within single cell suspensions of enzymatically digested cryobanked distal lung tissue retained expression of the pan-epithelial marker CD326 and the AT2 cell surface antigen recognized by monoclonal antibody HTII-280, allowing antibody-mediated enrichment and downstream analysis. Isolated AT2 cells from cryobanked tissue were comparable with those of freshly dissociated tissue both in their single cell transcriptome and their capacity for in vitro organoid formation in 3D cultures. We conclude that the cryobanking method described herein allows long-term preservation of distal human lung tissue for downstream analysis of lung cell function and molecular phenotype, and is ideally suited for creation of an easily accessible tissue resource for the research community.

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Acidified Nitrite Accelerates Wound Healing in Type 2 Diabetic Male Rats: A Histological and Stereological Evaluation

Molecules ◽

10.3390/molecules26071872 ◽

2021 ◽

Vol 26 (7) ◽

pp. 1872

Author(s):

Hamideh Afzali ◽

Mohammad Khaksari ◽

Sajad Jeddi ◽

Khosrow Kashfi ◽

Mohammad-Amin Abdollahifar ◽

...

Keyword(s):

Wound Healing ◽

Fibrous Tissue ◽

Diabetic Rats ◽

Male Rats ◽

Numerical Density ◽

Basal Cells ◽

Diabetic Wound Healing ◽

Diabetic Wounds ◽

Endothelial Growth Factor

Impaired skin nitric oxide production contributes to delayed wound healing in type 2 diabetes (T2D). This study aims to determine improved wound healing mechanisms by acidified nitrite (AN) in rats with T2D. Wistar rats were assigned to four subgroups: Untreated control, AN-treated control, untreated diabetes, and AN-treated diabetes. AN was applied daily from day 3 to day 28 after wounding. On days 3, 7, 14, 21, and 28, the wound levels of vascular endothelial growth factor (VEGF) were measured, and histological and stereological evaluations were performed. AN in diabetic rats increased the numerical density of basal cells (1070 ± 15.2 vs. 936.6 ± 37.5/mm3) and epidermal thickness (58.5 ± 3.5 vs. 44.3 ± 3.4 μm) (all p < 0.05); The dermis total volume and numerical density of fibroblasts at days 14, 21, and 28 were also higher (all p < 0.05). The VEGF levels were increased in the treated diabetic wounds at days 7 and 14, as was the total volume of fibrous tissue and hydroxyproline content at days 14 and 21 (all p < 0.05). AN improved diabetic wound healing by accelerating the dermis reconstruction, neovascularization, and collagen deposition.

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Differential expression of plasminogen activators and their inhibitors in an organotypic skin coculture system

Journal of Cell Science ◽

10.1242/jcs.106.1.45 ◽

1993 ◽

Vol 106 (1) ◽

pp. 45-53 ◽

Cited By ~ 1

Author(s):

C.S. Chen ◽

B. Lyons-Giordano ◽

G.S. Lazarus ◽

P.J. Jensen

Keyword(s):

Plasminogen Activator ◽

Plasminogen Activator Inhibitor ◽

Urokinase Plasminogen Activator ◽

Basal Cells ◽

Type Plasminogen Activator ◽

Inhibitor Type ◽

Activator Inhibitor Type ◽

Activator Inhibitor

Using immunohistochemistry and in situ hybridization, we have characterized the expression and localization of components of the plasminogen activator proteolytic cascade in an organotypic coculture system which consists of a “dermal” portion (human dermal fibroblasts throughout a collagen matrix) and a stratified, well-differentiated epidermal portion. Specifically, the following components were examined: the enzymes urokinase-type plasminogen activator and tissue-type plasminogen activator and their type 1 and type 2 inhibitors. Urokinase plasminogen activator mRNA and antigen were found predominantly in the least differentiated, basal keratinocytes; in some fields there was also faint deposition of antigen beneath the basal cells. The distribution of plasminogen activator inhibitor type 1 was similar to that of urokinase, except that inhibitor type 1 antigen deposition beneath the basal cells appeared more intense and uniform. In contrast to the results with urokinase plasminogen activator and inhibitor type 1, tissue plasminogen activator mRNA and antigen were localized focally in the suprabasal, i.e. more differentiated, keratinocytes. Plasminogen activator inhibitor type 2 mRNA and antigen were detected in most epidermal layers, but were more intense suprabasally and often spared the basal layer. These studies demonstrate that the same type of cell, i.e. the keratinocyte, can express different components of the plasminogen activator cascade depending on its state of differentiation. The change in expression of plasminogen activator cascade components with keratinocyte differentiation suggests distinct epidermal functions for these components, related to cell-matrix interaction and epidermal differentiation.

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Loss of Nrf2 promotes alveolar type 2 cell loss in irradiated, fibrotic lung

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2017.08.026 ◽

2017 ◽

Vol 112 ◽

pp. 578-586 ◽

Cited By ~ 7

Author(s):

Geri Traver ◽

Stacey Mont ◽

David Gius ◽

William E. Lawson ◽

George X. Ding ◽

...

Keyword(s):

Cell Loss ◽

Alveolar Type

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Hypercapnia limits β-catenin mediated alveolar type 2 cell progenitor function by altering Wnt production from adjacent fibroblasts

10.1101/2022.01.12.475264 ◽

2022 ◽

Author(s):

Laura A Dada ◽

Lynn C Welch ◽

Natalia D Magnani ◽

Ziyou Ren ◽

Patricia L Brazee ◽

...

Keyword(s):

Alveolar Type ◽

Mechanically Ventilated ◽

Persistent Symptoms ◽

Low Tidal Volume ◽

Lung Repair ◽

Ventilator Induced Lung Injury ◽

Lung Flooding ◽

Volume Ventilation

Persistent symptoms and radiographic abnormalities suggestive of failed lung repair are among the most common symptoms in patients with COVID-19 after hospital discharge. In mechanically ventilated patients with ARDS secondary to SARS-CoV-2 pneumonia, low tidal volume ventilation to reduce ventilator-induced lung injury necessarily elevate blood CO2 levels, often leading to hypercapnia. The role of hypercapnia on lung repair after injury is not completely understood. Here, we show that hypercapnia limits β-catenin signaling in alveolar type 2 (AT2) cells, leading to reduced proliferative capacity. Hypercapnia alters expression of major Wnts in PDGFRα-fibroblasts from those maintaining AT2 progenitor activity and towards those that antagonize β-catenin signaling and limit progenitor function. Activation of β-catenin signaling in AT2 cells, rescues the effects of hypercapnia on proliferation. Inhibition of AT2 proliferation in hypercapnic patients may contribute to impaired lung repair after injury, preventing sealing of the epithelial barrier, increasing lung flooding, ventilator dependency and mortality.

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