CTLA‑4 interferes with the HBV‑specific T cell immune response (Review)

Area of Science:

• Immunology
• Hepatology
• Virology

Background:

• Hepatitis B virus (HBV) infection causes liver inflammation.
• Effective HBV clearance relies on effector T cells.
• Chronic HBV infection is linked to T cell depletion and exhaustion, characterized by reduced reactivity and cytokine production.

Purpose of the Study:

• To review current literature on T cell exhaustion in chronic Hepatitis B.
• To discuss the role of Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) in HBV-related T cell exhaustion.

Main Methods:

• Review of existing scientific literature on Hepatitis B and T cell immunology.
• Analysis of the mechanisms of T cell exhaustion in the context of persistent HBV infection.

Main Results:

• Chronic HBV infection leads to T cell exhaustion, marked by impaired cytokine production and increased coinhibitory molecules like CTLA-4.
• Upregulation of CTLA-4 on hepatic CD8+ T cells in persistent HBV infection promotes apoptosis and blocks cytotoxic T lymphocyte activation.
• CTLA-4 upregulation also hinders CD4+ T helper cell proliferation and skews differentiation towards anti-inflammatory phenotypes, suppressing proinflammatory responses.

Conclusions:

• T cell exhaustion is a critical factor in the inability to clear chronic Hepatitis B.
• CTLA-4 is a significant contributor to T cell exhaustion in chronic HBV infection, impacting both CD8+ and CD4+ T cell functions.
• Targeting CTLA-4 may offer potential therapeutic strategies for improving immune control in chronic Hepatitis B.