Fig. 4. GARP on HSCs facilitates fibrogenesis by activating TGF-β.

(A) Flow cytometry analysis of GARP and LAP expression on the surface of HSCs isolated from GARP^fl/fl or GARP^ΔHSC mice and culture-activated for 7 days. (B) Schematic of TGF-β reporter assay using isolated HSCs and active TGF-β reporter cells. (C) TGF-β activation by HSCs from GARP^fl/fl or GARP^ΔHSC mice. (D) TGF-β activation by WT HSCs in the presence of anti-TGF-β1 or isotype antibody. (E) TGF-β activation by WT HSCs treated with scramble siRNA, or GARP siRNA, or incubated with PBS, or integrin inhibitor CWHM12. (F) Immunoblot of p-Smad2 or total Smad2 in the liver lysates of mice fed with TAA for 4 months or control naïve mice. (G) Representative images of IHC staining for p-Smad2 in the liver of mice fed with NASH diet for 8 weeks, or TAA for 4 months, or control naïve mice (left), and quantification of stained area (right). Scale bar 50 μm. Each data point represents one well in C-E or a single mouse in G. Data are presented as mean ± SEM. One-way ANOVA in C-D and unpaired t-test in E-G were used to compare two groups. ***p<0.001;****p<0.0001; NS, not significant.