A CD44/Brg1 nuclear complex confers mesenchymal progenitor cells with enhanced fibrogenicity in idiopathic pulmonary fibrosis
Libang Yang, … , Peter B. Bitterman, Craig A. Henke
Libang Yang, … , Peter B. Bitterman, Craig A. Henke
Published April 6, 2021
Citation Information: JCI Insight. 2021;6(9):e144652. https://doi.org/10.1172/jci.insight.144652.
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Research Article Pulmonology

A CD44/Brg1 nuclear complex confers mesenchymal progenitor cells with enhanced fibrogenicity in idiopathic pulmonary fibrosis

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease. We previously identified fibrogenic mesenchymal progenitor cells (MPCs) in the lungs of patients with IPF who serve as drivers of progressive fibrosis. Recent single-cell RNA sequencing work revealed that IPF MPCs with the highest transcriptomic network entropy differ the most from control MPCs and that increased CD44 was a marker of these IPF MPCs. We hypothesize that IPF MPCs with high CD44 (CD44hi) expression will display enhanced fibrogenicity. We demonstrate that CD44-expressing MPCs are present at the periphery of the IPF fibroblastic focus, placing them in regions of active fibrogenesis. In a humanized mouse xenograft model, CD44hi IPF MPCs are more fibrogenic than CD44lo IPF MPCs, and knockdown of CD44 diminishes their fibrogenicity. CD44hi IPF MPCs display increased expression of pluripotency markers and enhanced self-renewal compared with CD44lo IPF MPCs, properties potentiated by IL-8. The mechanism involves the accumulation of CD44 within the nucleus, where it associates with the chromatin modulator protein Brahma-related gene 1 (Brg1) and the zinc finger E-box binding homeobox 1 (Zeb1) transcription factor. This CD44/Brg1/Zeb1 nuclear protein complex targets the Sox2 gene, promoting its upregulation and self-renewal. Our data implicate CD44 interaction with the epigenetic modulator protein Brg1 in conveying IPF MPCs with cell-autonomous fibrogenicity.

Authors

Libang Yang, Hong Xia, Karen Smith, Adam Gilbertsen, Daniel Beisang, Jonathan Kuo, Peter B. Bitterman, Craig A. Henke

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Figure 3

CD44 regulates the fibrogenicity of CD44hi IPF MPCs.

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CD44 regulates the fibrogenicity of CD44hi IPF MPCs. NSG mice were treat...
NSG mice were treated with IT bleomycin (1.25 U/kg). Two weeks later, the mice received IPF MPCs (IPF424) transduced with either CD44 shRNA or scrambled shRNA via tail vein injection (106 cells/100 μL); 10 mice/group. Lungs were harvested 4 weeks after cell administration. (A) Collagen content was quantified in left lungs by Sircol assay. (B–K) Serial 4 μm sections of right lung tissue from mice receiving CD44hi IPF MPCs transduced with scrambled-shRNA or CD44-shRNA (B–E scale bar: 500 μm; F, G, I, and J scale bar: 50 μm; H and K scale bar: 20 μm). Representative H&E and Trichrome stains assessing fibrosis and collagen deposition, respectively (B–E). IHC using an antibody-recognizing human procollagen to identify human cells and assess collagen synthesis (F–H) and a CD44 antibody to determine the distribution of CD44-expressing cells (I–K). (F, G, I, and J) IHC for human procollagen (F and G) and CD44 (I and J) to assess the distribution of human cells expressing collagen and CD44-expressing cells from fibrotic and nonfibrotic lung regions from mice receiving CD44hi IPF MPCs transduced with scrambled shRNA. Data are expressed as mean ± SEM. P values in A were determined by 2-tailed t test.