IL-21R gene polymorphisms and serum IL-21 levels predict virological response to interferon-based therapy in Asian chronic hepatitis C patients

BACKGROUND

IL-21R polymorphisms have been identified as potential predictors of virological outcomes in Western chronic hepatitis C (CHC) patients receiving interferon-based treatment. We aimed to examine the associations of IL-21R genotypes and serum IL-21 levels with virological responses to interferon-based treatment in Asian CHC patients.

METHODS

Genomic and clinical data were collected from 178 consecutive Taiwanese HCV genotype 1 patients who received interferon-based therapy and 72 non-HCV healthy subjects. Among them, serum IL-21 levels, IL-21R and IL-28B genotypes were determined in 124 CHC patients and healthy controls.

RESULTS

Among patients with IL28B rs8099917 non-TT genotypes, patients with IL-21R rs3093390 CC genotype had a higher sustained virological response rate than those with non-CC genotypes (CC versus non-CC 14/24 versus 0/4; P = 0.031). Compared with non-HCV controls, CHC patients had higher serum IL-21 levels (mean ± sd HCV versus non-HCV 377.8 ± 780.9 versus 70.5 ± 33.2 pg/ml; P = 0.001). Patients with sustained virological response had higher pretreatment serum IL-21 levels than those without (adjusted OR 0.23, 95% CI 0.07, 0.80; P = 0.021).

CONCLUSIONS

CHC patients have higher serum IL-21 levels than healthy adults. Higher pretreatment serum IL-21 levels and IL-21R polymorphisms may serve as potential factors predictive of treatment outcomes in CHC patients with interferon-based therapy.

Interleukin-21 induces T-cell activation and proinflammatory cytokine secretion in rheumatoid arthritis

Interleukin (IL)-21 is a CD4+ T-cell-derived cytokine, which is involved in innate and adaptive immune response. In this study, we analysed IL-21 receptor (IL-21R) expression in peripheral blood and synovial fluid mononuclear cells, and investigated the role of IL-21 in the induction of proinflammatory cytokine production by peripheral blood T cells (PB-T) and synovial fluid T cells (SF-T) from patients with rheumatoid arthritis (RA). Immunohistochemical staining demonstrated that IL-21R-positive cells were significantly increased in inflamed synovial tissues of RA patients compared with osteoarthritis (OA) and healthy controls. Flow cytometric analysis confirmed that IL-21R was mainly expressed in freshly isolated CD4, CD8, B and NK cells from peripheral blood and synovial fluid, but decreased gradually in T cells 24 h after anti-CD3 stimulation. PB- and SF-T cells from RA patients were more responsive to IL-21 when compared with controls. Importantly, isolated PB- or SF-T cells from RA patients, when stimulated with IL-21 and anti-CD3 MoAb, secreted markedly higher levels of TNF-alpha and IFN-gamma than controls. These data indicate that IL-21R is overexpressed in the inflamed synovial membrane and in peripheral blood or synovial fluid leukocytes of RA patients, and that IL-21 enhances local T-cell activation, proliferation and proinflammatory cytokine secretion. Thus, blockade of IL-21R signalling pathway may have a therapeutic potential in acute RA patients.