Biology subjects

Bazarov, A. V.

Publications and source records attributed to Bazarov, A. V..

2 recordsLinked to original sources

bioRxiv2026

Comparative molecular analysis of histopathologic subtypes reveals shared epithelial remodeling yet distinct fibroblast programs in scleroderma lung disease

Rationale: Interstitial lung disease (ILD) drives mortality in systemic sclerosis (SSc), with a subset developing progressive pulmonary fibrosis (PPF) resembling idiopathic pulmonary fibrosis (IPF). Despite recognition of two distinct histopathologic patterns, the cellular basis of nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP) remains poorly understood. Objectives: To define shared and distinct cellular and molecular features of SSc-NSIP and SSc-UIP compared to IPF. Methods: Single-nucleus RNA sequencing and spatial transcriptomics were performed on explanted lungs from patients with SSc-NSIP (n=6), SSc-UIP (n=6), or IPF (n=6), and control donors (n=12) with immunohistochemistry and western blot validation. Main Results: Across 120,254 nuclei from 35 cell types, there was striking similarity across fibrotic subgroups in epithelial, endothelial, and immune compartments, including alveolar type 1 cell loss, pathologic alveolar type 2 (AT2) gene expression, and expansion of COL15A1 endothelial cells and profibrotic macrophages. Diseased AT2s showed activation of the p53/DNA damage pathway. Aberrant basaloid (AB) cells were present in both SSc-ILD subtypes and transcriptionally similar to IPF ABs. They consistently neighbored profibrotic CTHRC1 fibroblasts, even in SSc-NSIP, despite lacking fibroblast foci. Fibroblast heterogeneity differentiated the histopathologic subtypes. Inflammatory fibroblasts were enriched in SSc-NSIP and CTHRC1 fibroblasts in UIP. AB-to-pathologic fibroblast crosstalk was defined by profibrotic signaling, with amplified TGF-{beta} signaling in UIP. Conclusions: Convergent epithelial remodeling is a hallmark of PPF in SSc-ILD and IPF. Fibroblast heterogeneity characterized by altered TGF-beta signaling distinguishes SSc-NSIP from SSc-UIP and IPF. Accelerated aging, DNA damage, and p53-dependent senescence pathways may represent shared drivers of PPF.

genomics↗

bioRxiv2026

NINTEDANIB AND PIRFENIDONE AFFECT GROWTH AND DIFFERENTIATION OF HUMAN ALVEOLAR TYPE 2 CELLS

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease characterized by epithelial cell senescence. Pirfenidone and nintedanib are approved drugs for the treatment of IPF. They significantly slow disease progression, but their mechanisms of action, especially on alveolar type 2 (AT2) cells, are poorly understood. We addressed this question by evaluating colony formation and growth of human AT2 cells co-cultured with fibroblasts in organoid culture in the presence of pirfenidone and nintedanib. We further evaluated molecular changes induced by these drugs via single cell RNA-seq of treated organoids. MethodsAT2 cells isolated from normal donor lungs or IPF patients were mixed with human fibroblasts in 3D culture and grown in the absence or presence of pirfenidone or nintedanib. After 14 days in culture, the organoids were quantified and cells extracted from Matrigel for single cell RNA-seq. ResultsAT2 cell organoids cultured in the presence of pirfenidone or nintedanib resulted in increased colony formation and, in the case of nintedanib, in larger colonies. We observed that untreated or pirfenidone treated AT2 cells lost surfactant protein C (SFTPC) expression and acquired an expression profile consistent with keratin (KRT)17high/KRT5- basaloid cells, whereas a larger proportion of nintedanib treated cells retained SFTPC expression. In contrast, AT2 cells treated with TGF{beta} inhibitor exhibited intermediate (SFTPC-/KRT17low) gene expression profile. ConclusionThese results suggest that nintedanib maintains an AT2-like expression state in culture and acts proximal to TGF{beta}. Conflict of Interest StatementPJW was supported by grants from Boehringer Ingelheim, Roche, Sanofi, Pliant and Arda Therapeutics and received personal fees from Boehringer Ingelheim and Sanofi. None of these companies had a role in the design or analysis of the study or in the writing of the manuscript. ASM, GP, JRR and DG are employees of Genetech. The other authors have no conflicts of interest to declare.

cell biology↗