THBS1 Orchestrates MASH Fibrosis by Linking Fibroblasts and Macrophages; Nintedanib and LSKL Disrupt This Circuit

Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as non-alcoholic steatohepatitis (NASH), is a progressive liver disease characterized by inflammation and fibrosis, often leading to cirrhosis and liver failure. A key driver of fibrosis is transforming growth factor-β1 (TGF-β1), but the intricate communication between stromal and immune cells that fuels this process, particularly involving Thrombospondin-1 (THBS1), remains incompletely understood. Current treatments for MASH are limited, highlighting an urgent need for novel therapeutic targets that can effectively interrupt the fibroinflammatory cascade.

Researchers examined THBS1 expression in liver tissue and serum from MASLD patients and in two dietary murine MASH models. They integrated single-cell RNA sequencing, immunohistochemistry, confocal microscopy, and flow cytometry to characterize cellular THBS1 sources. Targeted perturbation strategies included treating murine models with nintedanib (an existing antifibrotic drug), the THBS1-blocking peptide LSKL, and siRNA-mediated THBS1 silencing. In vitro studies used THBS1 knockdown or blockade to assess effects on TGF-β1-induced fibroblast activation and LPS-stimulated macrophage inflammation.

THBS1 and the fibroblast activation marker FAP significantly increased in human MASLD liver tissue, correlating with fibrosis severity and interleukin-6 (IL-6) levels. Single-cell RNA sequencing and spatial imaging confirmed THBS1 expression in both FAP+ fibroblasts and monocyte-derived macrophages, underscoring a coordinated fibroinflammatory niche. Treatment with nintedanib reduced THBS1 expression in both fibroblast and macrophage compartments, leading to decreased CD11b+MERTK+ macrophages and FAP+PD-L1+ fibroblasts, and improved histologic fibrosis.

Direct THBS1 inhibition via the LSKL peptide produced similar antifibrotic effects in murine models. In vitro, THBS1 knockdown or blockade suppressed TGF-β1-induced fibroblast activation and significantly reduced lipopolysaccharide-stimulated IL-1β and IL-6 production in macrophages, providing strong evidence for reciprocal THBS1-dependent stromal-immune signaling.