CC-chemokine receptor 5 (CCR5) in hepatitis C--at the crossroads of the antiviral immune response?

An effective immune response to hepatitis C virus (HCV) infection requires efficient recruitment and activation of inflammatory cells to the liver, the site of infection. Chemokines are critically involved in this process, since they exert both chemotactic and immunoregulatory actions. In particular, the interaction between chemokines CCL3 (MIP-1alpha), CCL4 (MIP-1beta) and CCL5 (RANTES) and their receptor, CC-chemokine receptor 5 (CCR5), may be critical in regulating T cell functions by mediating recruitment, polarization, activation and differentiation of antiviral type 1 cytokine secreting T helper and cytotoxic T cells. A 32 bp deletion in the encoding region of CCR5 leads to complete loss of the functional CCR5 receptor in subjects homozygous for this mutation and decreased expression in heterozygous patients. This fact provides the unique opportunity to study the role of the CCR5 receptor in chronic hepatitis C infection by comparing immune responses between HCV infected CCR5-Delta32 carriers and CCR5 wild-type patients. This article will summarize and discuss the available data with respect to possibly altered disease susceptibility, clinical course and treatment outcomes associated with the CCR5-Delta32 mutation in hepatitis C.