Figure 2
From: Toll-like receptor 4 signaling in liver injury and hepatic fibrogenesis
Activation of the Toll-like receptor (TLR)4 signaling in liver injuries. Exogenous and endogenous ligand(s) of TLR4 are increased during liver injuries caused by various etiologies such as nonalcoholic steatohepatitis (NASH). Activation of TLR4 by both pathogen-associated molecular patterns (PAMPs; exogenous ligands, for example, lipopolysaccharide (LPS)) and damage-associated molecular patterns (DAMPs; endogenous ligands, for example, high mobility group box (HMGB)1) induces pre-inflammatory cytokines and chemokines, thereby enhancing liver inflammation, injury and fibrogenesis. TLR4 activation also enhances interferon (IFN)-β and IFN-stimulated gene expression, which have inhibitory effects on hepatitis viruses.