Probiotics counteract the expression of hepatic profibrotic genes via the attenuation of TGF-β/SMAD signaling and autophagy in hepatic stellate cells

Hepatic fibrosis is caused by the increased accumulation and improper degradation of extracellular matrix (ECM) proteins in the liver. Hepatic stellate cells (HSCs) activation is a key process in initiating hepatic fibrosis and can be ameliorated by the administration of probiotic strains. This study hypothesized that LAB strains (Lactiplantibacillus plantarum, Lactobacillus brevis, and Weissella cibaria) might attenuate pro-fibrogenic cytokine TGF-beta mediated HSCs activation and induce collagen deposition, expression of other fibrogenic/inflammatory markers, autophagy, and apoptotic processes in vitro. Few studies have evaluated the probiotic effects against fibrogenesis in vitro. In this study, TGF-beta exposure increased collagen deposition in LX-2 cells, but this increase was diminished when the cells were pretreated with LAB strains before TGF-beta stimulation. TGF-beta not only increased collagen deposition, but it also significantly upregulated the mRNA levels of Coll Al , alpha-smooth muscle actin (alpha-SMA), matrix metalloproteinases-2 (MMP-2), IL-6, CXCL-8, CCL2, and IL-1 beta in LX-2 cells. Pretreatment of the cells with LAB strains counteracted the TGF-beta-induced pro-fibrogenic and inflammatory markers by modulating SMAD-dependent and SMAD-independent TGF-beta signaling. In addition, LX-2 cells exposed to TGF-beta induced the autophagic and apoptotic associated proteins that were also positively regulated by the LAB strains. These findings suggest that LAB can attenuate TGF-beta signaling that is associated with liver fibrogenesis.