Abstract
Interleukin 17A (IL-17A)-producing T helper 17 (Th17) cells were identified as a subset
of T helper cells that play a critical role in host defense against bacterial and
fungal pathogens. Th17 cells differentiate from Th0 naïve T-cells in response to transforming
growth factor β1 (TGF-β1) and IL-6, the cytokines which also drive development of
liver fibrosis, require activation of transcription factor retinoic acid receptor-related
orphan nuclear receptor gamma t (RORγt). IL-17A signals through the ubiquitously expressed receptor IL-17RA. Expression
of IL-17RA is upregulated in patients with hepatitis B virus/hepatitis C virus (HBV/HCV)
infections, nonalcoholic steatohepatitis (NASH), alcohol-associated liver disease
(AALD), hepatocellular carcinoma (HCC), and experimental models of chronic toxic liver
injury. The role of IL-17 signaling in the pathogenesis of NASH- and AALD-induced
metabolic liver injury and HCC will be the focus of this review. The role of IL-17A–IL-17RA
axis in mediation of the cross-talk between metabolically injured hepatic macrophages,
hepatocytes, and fibrogenic myofibroblasts will be discussed.
Keywords
IL-17 signaling - metabolic syndrome - lipogenesis - TNF signaling