TLR2 and hepatocellular carcinoma: For instance, lipoteichoic acid (LTA, a Gram-negative bacterial cell wall component) and deoxycholic acid (DCA, a secondary bile acid produced by bacteria) collaboratively induced the expression of prostaglandin-endoperoxide synthase 2 or cyclooxygenase-2 (COX-2) through Toll-like receptor 2 (TLR-2) in senescent hepatic stellate cells (HSCs) to enlarge prostaglandin E2 (PGE2)-mediated inhibition of antitumor immunity, resulting in HCC progression (13).