TGFB1 and pulmonary fibrosis: In contrast to pulmonary fibrosis, the impact of PDL1 on liver fibrosis primarily stems from its immunomodulatory functions(Figure 5): firstly, in the context of hepatitis C, upregulated PDL1 in hepatocytes induces the generation of Tregs and follicular regulatory T cells, releasing exosomes rich in TGF-β.