IL-17A in hepatitis B infection: friend or foe?

Hepatitis B virus (HBV) is one of the most prevalent and infectious agents that leads to liver disease in humans. Five clinical forms of HBV infection exist, including fulminant, acute, chronic, asymptomatic and occult. The chronic, asymptomatic and occult forms are long-term infections that can lead to hepatocellular carcinoma (HCC) and liver cirrhosis. The mechanisms responsible for progression of these forms of the infection to HCC and liver cirrhosis are not yet clearly understood or characterised. However, genetic and immunological parameters may play important roles in the disease. IL-17A is an important cytokine involved in early immune responses against fungal and bacterial infections, but its role in the response against viral infections is yet to be fully clarified. The crucial roles of IL-17A in the pathogenesis of autoimmune and destructive immune-related diseases have been documented and may provide insights into its functions during hepatitis infection. Therefore, the aim of this review was to address the recent information regarding the status and association of IL-17A during hepatitis B infection and its related disorders, including HCC and liver cirrhosis.