TLR2 and hepatocellular carcinoma: Human hepatocellular carcinoma- (HCC-) derived exosomes containing high mobility group box 1 (HMGB1) promote the proliferation of the T cell immunoglobulin domain and mucin domain protein-1 positive regulatory B (TIM-1+ Breg) cells by inducing the Toll-like receptor/mitogen-activated protein kinase (TLR/MAPK) pathway and the production of IL-10, an immunosuppressive cytokine, thus working against CD8+ T cells through the TLR2/4-MAPK pathway and leading to immune surveillance failure [36] (Figure 1).