IL-21 collaborates with anti-TIGIT to restore NK cell function in chronic HBV infection.

Available therapies for chronic hepatitis B virus (HBV) infection are not satisfying, and interleukin-21 (IL-21) and checkpoint inhibitors are potential therapeutic options. However, the mechanism underlying IL-21 and checkpoint inhibitors in treating chronic HBV infection is unclear. To explore whether IL-21 and checkpoint inhibitors promote HBV clearance by modulating the function of natural killer (NK) cells, we measured the phenotypes and functions of NK cells in chronic HBV-infected patients and healthy controls on mRNA and protein levels. We found that chronic HBV infection disturbed the transcriptome of NK cells, including decreased expression of KLRK1, TIGIT, GZMA, PRF1, and increased expression of CD69. We also observed altered phenotypes and functions of NK cells in chronic HBV-infected patients, characterized by decreased NKG2D expression, increased TIGIT expression and impaired interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) production. Furthermore, these alterations cannot be restored by telbivudine treatment but can be partially restored by IL-21 and anti-TIGIT stimulation. IL-21 upregulated the expression of activating receptor CD16, CD69, and NKG2D on NK cells, enhanced IFN-γ production, cytolysis, and proliferation of NK cells, while anti-TIGIT promoted IFN-γ production in CD56dim subset exclusively in chronic HBV infected patients. Additionally, IL-21 was indispensable for anti-TIGIT in HBsAg clearance in mice bearing HBV. It enhanced IFN-γ production in splenic NK cells rather than intrahepatic NK cells, indicating a brand-new mechanism of IL-21 in HBV clearance when combined with anti-TIGIT. Overall, our findings contribute to the design of immunotherapy through enhancing the antiviral efficacy of NK cells in chronic HBV infection.

Pre-existing immunity to SARS-CoV-2 associates with strong T cell responses induced by inactivated COVID-19 vaccines.

Individuals with a recent common cold coronavirus infection, which leads to pre-existing immunity against SARS-CoV-2, displayed a less severe course of COVID-19. However, the relationship between pre-existing immunity against SARS-CoV-2 and the inactivated-vaccine-induced immune response is still unknown. Here, 31 healthcare workers who received standard two doses of inactivated COVID-19 vaccines (Weeks 0 and 4, respectively) were enrolled, vaccine-induced neutralization and T cell responses were detected, and the correlation between the pre-existing SARS-CoV-2-specific immunity was analyzed. We found the SARS-CoV-2-specific antibodies, pseudovirus neutralization test (pVNT) titers, and spike-specific interferon gamma (IFN-γ) production in CD4+ and CD8+ T cells were significantly elevated after two doses of inactivated vaccines. Interestingly, the pVNT titers after the second dose of vaccination displayed no significant correlation with the pre-existing SARS-CoV-2-specific antibodies or B cells, nor the pre-existing spike-specific CD4+ T cells. Notably, the spike-specific T cell response after the second dose of vaccination was positively correlated with the pre-existing receptor binding domain (RBD)-specific B cells and CD4+ T cells, which were documented by the frequencies of RBD-binding B cells, the breadth of RBD-specific B cell epitopes, and the frequency of IFN-γ-expressing RBD-specific CD4+ T cells. Overall, the inactivated-vaccine-induced T cell responses, not the inactivated-vaccine-induced neutralization, closely correlated with pre-existing immunity to SARS-CoV-2. Our results provide a better understanding of inactivated-vaccine-induced immunity and help predict the immunogenicity induced by inactivated vaccines in individuals.

[Long-term assessment of relapse and associated risk factors in chronic hepatitis C patients treated with interferon and ribavirin].

OBJECTIVE: To investigate viral relapse and the associated risk factors during a long-term follow-up study of chronic hepatitis C (CHC) patients who achieved end-of-treatment response (ETR) after interferon and ribavirin therapy. METHODS: This retrospective study was conducted on 146 CHC patients treated with a combination of ribavirin and pegylated (PEG) interferon-alpha (IFNa) (n=126) or conventional IFNa (n=20) for 24 (hepatitis C virus (HCV) non-genotype 1b) or 48 (HCV genotype 1b) weeks. The main outcome measure was serum HCV RNA load. The risk factors analyzed included age, sex, HCV genotype, baseline HCV RNA load, and IFN type. RESULTS: The mean follow-up time for all patients was 33.45+/-16.41 months (range: 12-85 months). The cumulative relapse rate during follow-up was 14.80%. The relapse rate within six months (8.90%) was significantly higher than other periods during two years of follow-up, and no relapse occurred after 30 months. Of all relapsers (n=20), 65% occurred within six months, followed by 35% within 7-24 months after antiviral therapy. The relapse rates in patients with HCV genotype 1b and non-1b were not significantly different (20.37% vs. 12.12%, X2 =1.517, P=0.315). The mean baseline HCV RNA load was significantly higher in the relapsers than that in the non-relapsers (t=0.915, P=0.362). Relapse rates were similar in patients treated with PEG-IFNa-2b, PEG-IFNa-2a and IFNa (12.12% vs. 13.97% vs. 15.00%, respectively; X2=0.104, p=0.949). The mean age of relapsers was significantly higher than that of non-relapsers (P less than 0.005). CONCLUSION: The maximum probability of relapse for CHC patients exists within six months from when ETR is achieved by interferon and ribavirin therapy. A lower risk for relapse persists past this period. Thus, ETR CHC patients, especially older patients, should be carefully monitored during the two years after cessation of antiviral therapy. Standard antiviral therapy based on HCV genotype eliminates the influence of viral factors on treatment-response.