Aberrant basement membrane production by hepatic stellate cells in MASLD is attenuated by the bile acid analog INT-767
Background: The farnesoid X receptor (FXR) is a leading therapeutic target for MASH-related fibrosis. INT-767, a potent FXR agonist, has shown promise in preclinical models. We aimed to define the mechanisms of INT-767 activity in experimental MASH and dissect cellular and molecular targets of FXR agonism in human disease. Methods: Leptin-deficient ob/ob mice were fed a MASH-inducing diet for 15 weeks prior to study start. After baseline liver biopsy and stratification, mice were allocated to INT-767 (10 mg/kg/day) or vehicle treatment for 8 weeks, either alongside ongoing MASH diet (progression) or following conversion to normal chow (reversal). Effects on extracellular matrix remodelling were analyzed histologically and by RNA-sequencing. Serum fibrosis biomarkers were measured longitudinally. Human liver samples were investigated using bulk and single-cell RNA-sequencing, histology, and cell culture assays.  Results: INT-767 treatment was antifibrotic during MASH progression but not reversal, attenuating accumulation of type I collagen and basement membrane proteins (type IV collagen, laminin). Circulating levels of PRO-C4, a type IV collagen formation marker, were reduced by INT-767 treatment and correlated with fibrosis. Expression of basement membrane constituents also correlated with fibrosis severity and adverse clinical outcomes in human MASH. Single-cell RNA-sequencing analysis of mouse and human livers, and immunofluorescence staining colocalized FXR and basement membrane expression to myofibroblasts within the fibrotic niche. Treatment of culture-activated primary human hepatic stellate cells with INT-767 decreased expression of basement membrane components. Conclusion: These findings highlight the importance of basement membrane remodelling in MASH pathobiology and as a source of circulating biomarkers. Basement membrane deposition by activated hepatic stellate cells is abrogated by INT-767 treatment and measurement of basement membrane molecules should be included when determining the therapeutic efficacy of FXR agonists. Overall design: RNA-seq of poly A-enriched RNA isolated from AMLN ob/ob-MASH mouse model following treatment with INT-767 (n=4) or vehicle (n=7).