Tim-3 expression on peripheral T cell subsets correlates with disease progression in hepatitis B infection

BACKGROUND AND OBJECTIVE: T-cell immunoglobulin domain and mucin domain-containing molecule-3 (Tim-3) represents a novel mechanism of T-cell dysfunction in chronic viral diseases. However, the role of Tim-3 in the pathogenesis of chronic hepatitis B (CHB) is not well understood. We investigated Tim-3 expression on peripheral T cell subsets and analyzed the relationship between Tim-3 expression and disease progression in HBV infection. METHODS: peripheral blood samples were obtained from CHB patients (n = 40), including 23 patients with moderate CHB [MCHB] and 17 with severe CHB [SCHB]. Control samples were obtained from nine acute hepatitis B patients (AHB) and 26 age-matched healthy subjects. The expression of Tim-3 on T cells was determined by flow cytometry. RESULTS: Tim-3 expression was elevated on peripheral CD4(+ )and CD8(+ )T cells from AHB and CHB patients compared to those from healthy controls. The percentage of Tim-3(+ )T cells was further increased in SCHB patients relative to MCHB patients and showed a positive correlation with conventional markers for liver injury (alanine aminotransferase (ALT), aspartate transaminase (AST), total bilirubin (TB) and international normalized ratio (INR) level). The frequency of Tim-3-expressing T cells was negatively correlated with T-bet mRNA expression and plasma interferon-gamma (INF-gamma) levels. Further, Tim-3 expression on CD4(+ )or CD8(+ )T cells was reduced in CHB patients with disease remission after antiviral treatment and in AHB patients during the convalescence phase. CONCLUSIONS: Our results suggest that over-expression of Tim-3 is involved in disease progression of CHB and that Tim-3 may participate in skewing of Th1/Tc1 response, which contributes to persistency of HBV infection.