Hepatitis B virus (HBV)-specific CD8 T cells are functionally exhausted in chronic hepatitis B infection, and this condition can be corrected only partially through the modulation of inhibitory pathways, which suggests that a more complex molecular interplay underlies T cell exhaustion. To gain broader insight into this process and identify additional targets for the restoration of T cell function, we compared the transcriptome profiles of HBV-specific CD8 T cells from patients with acute and chronic disease with those of HBV-specific CD8 T cells from patients able to resolve HBV infection spontaneously and influenza (FLU)-specific CD8 T cells from healthy participants. The results indicate that exhausted HBV-specific CD8 T cells are markedly impaired at multiple levels and show substantial downregulation of various cellular processes centered on extensive mitochondrial alterations. A notable improvement of mitochondrial and antiviral CD8 functions was elicited by mitochondrion-targeted antioxidants, which suggests a central role for reactive oxygen species (ROS) in T cell exhaustion. Thus, mitochondria represent promising targets for novel reconstitution therapies to treat chronic hepatitis B infection.
The goal of antiviral therapy is to improve the quality of life and survival of patients with chronic hepatitis B (CHB) by halting the progression to cirrhosis, end‐stage liver disease or hepatocellular carcinoma (HCC), thus preventing anticipated liver‐related death. Oral administration of potent and less resistance‐prone nucleot(s)ide analogues (NUCs), such as entecavir (ETV) and tenofovir disoproxil fumarate (TDF) has become the most popular treatment strategy worldwide because of their excellent efficacy and safety profile as well as easy management confirmed in both registration trials and in clinical practice studies. Long‐term administration of ETV or TDF suppresses HBV replication in >95% of patients, resulting in biochemical remission, histological improvement including the regression of cirrhosis and prevention or reversal of clinical decompensation but not the development of HCC, particularly in patients with cirrhosis. Moreover, NUCs can be administered to all patients including those with severe liver disease, the elderly and in those who do not respond, are unwilling to take or have contraindications to interferon. The need for long‐term, perhaps indefinite, treatment is the main limitation of NUCs therapy with the associated costs, unknown long‐term safety and the low rates of hepatitis B surface antigen (HBsAg) seroclearance, which is still the best stopping rule for NUCs‐treated patients with cirrhosis.
Patients with chronic hepatitis B virus (HBV) infection lacking the serum hepatitis B e antigen (HBeAg) and with antibodies against HBeAg (anti-HBe), are the prevalent subgroup of HBV carriers worldwide. The prognosis of these patients is different from inactive carriers (ICs), who are characterized by persistently normal serum alanine aminotransferase (ALT) and low (<2000 IU/ml) serum HBV DNA levels, a serological profile that may also be intermittently observed in patients with HBeAgnegative chronic hepatitis. This is why a confirmed diagnosis of IC requires quarterly ALT and HBV DNA measurements for at least 1 year, while a single-point detection of combined HBsAg <1000 IU/ml and HBV DNA <2000 IU/ml has a robust predictive value for the diagnosis of IC. Characteristically, ICs have minimal or no histological lesions of the liver corresponding to liver stiffness values on Fibroscan of <5 kPa. Antiviral treatment is not indicated in ICs since the prognosis for the progression of liver disease is favourable if there are no cofactors of liver damage such as alcohol abuse, excess weight or co-infection with the hepatitis C virus or delta virus. Moreover, spontaneous HBsAg loss frequently occurs (1-1.9% per year) in these patients while the development of hepatocellular carcinoma (HCC) is rare, at least in Caucasian patients. However, an emerging issue reinforcing the need for clinical surveillance of ICs is the risk of HBV reactivation in patients who undergo immunosuppressive therapy without receiving appropriate antiviral prophylaxis. After diagnosis, management of ICs includes monitoring of ALT and HBV DNA every 12 months with periodic measurement of serum HBsAg levels to identify viral clearance.
The goal of antiviral therapy in patients with chronic hepatitis B (CHB)is to improve quality of life and survival by preventing the progression of liver disease and early liver-related deaths. This can be achieved by sustained or maintained suppression of hepatitis B virus (HBV) replication either by pegylated interferon (Peg-IFN) or with nucleot(s) ide analogues (NUCs), i.e. entecavir (ETV), tenofovir disoproxil fumarate (TDF) and recently approved tenofovir alafenamide (TAF).
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