Hepatitis B virus-persistent infection and innate immunity defect: Cell-related or virus-related?

Pathogenesis of Viral Hepatitis-Induced Chronic Liver Disease: Role of Extracellular Vesicles

Extracellular vesicles are encapsulated lipid nanoparticles secreted by a variety of cell types in living organisms. They are known to carry proteins, metabolites, nucleic acids, and lipids as their cargoes and are important mediators of intercellular communication. The role of extracellular vesicles in chronic liver disease has been reported. Chronic liver disease such as viral hepatitis accounts for a significant mortality and morbidity burden worldwide. Hepatic fibrosis has been commonly associated with the chronic form of viral hepatitis, which results in end-stage liver disease, including cirrhosis, liver failure, and carcinoma in some patients. In this review, we discuss the potential role of extracellular vesicles in mediating communication between infectious agents (hepatitis B and C viruses) and host cells, and how these complex cell-cell interactions may facilitate the development of chronic liver disease. We will further discuss how understanding their biological mechanism of action might be beneficial for developing therapeutic strategies to treat chronic liver disease.

TIM-3 as a marker of exhaustion in CD8+ T cells of active chronic hepatitis B patients

BACKGROUND

Chronic HBV infection presents weak or no virus-specific T-cell responses, implying to an exhausted phenotype, characterized by overexpression of several inhibitory receptors. In the present study, it was aimed to characterize the panel of inhibitory molecules on the CD8⁺ T cells in patients with active chronic HBV infection.

METHODS

In this study, 31 active and 32 inactive individuals with chronic HBV infection were recruited. Peripheral blood mononuclear cells were isolated and a multicolor flow cytometry was applied to evaluate the surface inhibitory molecules of TIM3, PD-1, and CD39.

RESULTS

CD8⁺ T cells expressing TIM3 were significantly higher in cases with active chronic HBV infection compared to inactive chronic HBV group (8.43 ± 1.4 vs. 5.15 ± 1.43; P < 0.0001). CD8⁺TIM3⁺PD-1⁺ T cells were significantly higher in active chronic HBV cases in comparison to the inactive chronic HBV subjects (4.26 ± 1.04 vs. 3.41 ± 0.74; P < 0.001). Different subpopulations of the CD8⁺ T cells were correlated with the duration of infection and HBV DNA load in the cases with active chronic HBV infection.

CONCLUSION

It appears that CD8⁺ TIM3⁺ T cells are the major exhausted phenotype of T cells during the active state of HBV infection.