Xia, H.

Abstract RATIONALE: Mesenchymal progenitor cells (MPCs) in the lungs of individuals with Idiopathic Pulmonary Fibrosis (IPF) show intrinsic fibrogenic properties, possessing a distinct transcriptomic profile and maintaining fibrogenic activity, which contributes to the fibroblast population in IPF. We hypothesize that IPF MPCs are distinguished from control MPCs by a unique gene interaction network. METHODS: We analyzed bulk RNA-seq data, available on the Gene Expression Omnibus (GEO) under accession numbers GSE97038 and GSE276568. In these experiments, CD44hi MPCs were isolated through flow cytometry from mesenchymal cell lines derived from IPF patients (explanted lungs from live IPF patients after lung transplant) and control subjects (lobectomy for clinical reasons) using antibodies against CD44 and SSEA4. The pooled dataset comprises nine IPF and nine control MPC lines. We identified differentially expressed genes (DEGs) in IPF MPCs compared to controls using DESeq and performed pathway enrichment analysis on DEGs using Gene Ontology (GO). We also conducted Gene Set Enrichment Analysis (GSEA) with gene sets related to stemness, pluripotency, and self-renewal. Weighted gene co-expression network analysis (WGCNA) identified functional modules specifically associated with IPF MPCs. RESULTS: Applying an adjusted p-value threshold of 0.05, we identified 134 DEGs in IPF MPCs compared to controls. GO analysis showed significant enrichment in pathways associated with leukocyte migration, extracellular matrix organization, and cell differentiation and growth. GSEA highlighted significant enrichment in two gene sets related to stemness, with adjusted p-values of 0.002 and 0.048. Using WGCNA, we identified 16 functional modules, one of which reached significance based on an adjusted p-value threshold of 0.05 and a correlation coefficient cutoff of 0.45. This significant module demonstrated a positive correlation with IPF status (correlation coefficient of 0.69, adjusted p-value 0.0085). CONCLUSION: This study is the first to characterize a distinct gene expression profile in IPF MPCs compared to controls, highlighting enriched biological processes relevant to IPF pathogenesis. GSEA results further support the hypothesis that IPF MPCs display stem cell-like gene expression patterns, including genes associated with pluripotency and self-renewal. Additionally, we identified functional gene modules that significantly correlate with the fibrogenic properties of IPF MPCs, including hub genes that may play critical roles in promoting fibrosis in IPF. These findings deepen our understanding of IPF MPC biology and identify potential targets for future research. We plan to expand this approach by increasing the sample size to enhance statistical power, aiming to identify more robust functional modules and their highly connected hub genes.