The role of regulatory T cells and follicular T helper cells in HBV infection

Varied immune responses of HBV-specific B cells in patients undergoing pegylated interferon-alpha treatment for chronic hepatitis B

BACKGROUND & AIMS

The changes in HBV-specific B cells in patients with chronic hepatitis B (CHB) undergoing pegylated interferon-α (PEG-IFNα) treatment and achieving functional cure remain unclear. We aimed to evaluate the alterations in HBV-specific B cells during treatment and therefore explored the mechanism of functional recovery of HBsAg-specific B cells.

METHODS

We included 39 nucleos(t)ide analogue-treated patients with CHB who received sequential combination therapy with PEG-IFNα and eight treatment-naïve patients. HBV-specific B cells were characterized ex vivo using fluorescently labeled hepatitis B surface and core antigens (HBsAg and HBcAg). The frequency, phenotype, and subsets of HBV-specific B cells and follicular helper T cells (Tfh cells) were detected using flow cytometry. The functionality of HBV-specific B cells was quantified through ELISpot assays.

RESULTS

During treatment, the fraction of activated memory B cells (MBCs) among HBsAg-specific B cells and the expression of IgG, CXCR3, and CD38 increased. The antibody-secretion capacity of HBsAg-specific B cells was only restored in patients achieving a functional cure after treatment and it positively correlated with serum hepatitis B surface antibody levels. The phenotype and function of HBsAg-specific B cells differed between patients with and without functional cure. Patients with functional cure exhibited IgG+ classical MBCs and plasmablasts among HBsAg-specific B cells. HBcAg-specific B cells displayed both attenuated antibody secretion with reduced IgG expression and an IgM+ atypical type of MBC after treatment, irrespective of functional cure. The number of CD40L+ Tfh cells increased after PEG-IFNα treatment and positively correlated with HBsAg-specific B-cell activation.

CONCLUSIONS

After PEG-IFNα treatment, HBsAg- and HBcAg-specific B cells exhibit various changes in antibody secretion. Their functional differences are reflected in the alterations in phenotypes and subtypes. The presence of CD40L+ Tfh cells is associated with the active recovery of HBsAg-specific B cells.

IMPACT AND IMPLICATIONS

HBV-related complications and hepatocellular carcinoma remain the leading causes of mortality from chronic liver disease worldwide, and a cure is rarely achieved with antiviral therapies. Elucidating the immunological mechanisms underlying the functional cure of patients with chronic hepatitis B offers a promising therapeutic strategy for viral clearance, e.g. via therapeutic vaccination. We analyzed the alterations in HBV-specific B cells in patients treated with pegylated interferon-α and identified novel pathways for immunotherapeutic boosting of B cell immunity.

Understanding lactate in the development of Hepatitis B virus-related hepatocellular carcinoma

Hepatitis B Virus (HBV) is a hepatotropic virus that can establish a persistent and chronic infection in humans. Chronic hepatitis B (CHB) infection is associated with an increased risk of hepatic decompensation, cirrhosis, and hepatocellular carcinoma (HCC). Lactate level, as the end product of glycolysis, plays a substantial role in metabolism beyond energy production. Emerging studies indicate that lactate is linked to patient mortality rates, and HBV increases overall glucose consumption and lactate production in hepatocytes. Excessive lactate plays a role in regulating the tumor microenvironment (TME), immune cell function, autophagy, and epigenetic reprogramming. The purpose of this review is to gather and summarize the existing knowledge of the lactate's functions in the dysregulation of the immune system, which can play a crucial role in the development of HBV-related HCC. Therefore, it is reasonable to hypothesize that lactate with intriguing functions can be considered an immunomodulatory metabolite in immunotherapy.

Cytokine IL-5 and HGF: combined prediction of non-/low immune response to hepatitis B vaccination at birth in infants born to HBsAg-positive mothers

Background

The immune response to hepatitis B vaccine may be influenced by numerous factors, and patients with non/low response re-exposed to hepatitis B virus remain susceptible. Thus, a better understanding of the underlying mechanisms of non/low immune response in infants born to Hepatitis B surface antigen (HBsAg)-positive mothers is essential.

Methods

100 infants born to HBsAg-positive mothers from 2015 to 2020 were enrolled in the study, further divided into the non/low response group (n=13) and the moderate strong response group (n=87) based on the quantification of hepatitis B surface antibody at 12 months of age. The differential expression of 48 immune-related cytokines in the two groups was compared and analyzed in detail. The key cytokines were further identified and clinically predictive models were developed.

Results

We found that 13 cytokines were lowly expressed and one cytokine was highly expressed in the non/low response group, compared with the moderate strong response group at birth. In addition, 9 cytokines were lowly expressed and one cytokine was highly expressed in the non/low response group at 12 months of age. Furthermore, we found that IL-5 and HGF were promising predictors for predicting the immunization response to hepatitis B vaccine in infants, and the combination of the two cytokines showed the best predictive efficiency, with an area under the curve (AUC) value of 0.844.

Conclusion

The present study provides a theoretical basis on cytokines for developing and implementing effective immunotherapies against non/low immune response in infants born to HBsAg-positive mothers.

AAV Immunotoxicity: Implications in Anti-HBV Gene Therapy

Hepatitis B virus (HBV) has afflicted humankind for decades and there is still no treatment that can clear the infection. The development of recombinant adeno-associated virus (rAAV)-based gene therapy for HBV infection has become important in recent years and research has made exciting leaps. Initial studies, mainly using mouse models, showed that rAAVs are non-toxic and induce minimal immune responses. However, several later studies demonstrated rAAV toxicity, which is inextricably associated with immunogenicity. This is a major setback for the progression of rAAV-based therapies toward clinical application. Research aimed at understanding the mechanisms behind rAAV immunity and toxicity has contributed significantly to the inception of approaches to overcoming these challenges. The target tissue, the features of the vector, and the vector dose are some of the determinants of AAV toxicity, with the latter being associated with the most severe adverse events. This review discusses our current understanding of rAAV immunogenicity, toxicity, and approaches to overcoming these hurdles. How this information and current knowledge about HBV biology and immunity can be harnessed in the efforts to design safe and effective anti-HBV rAAVs is discussed.

Reprogramming of Treg cells in the inflammatory microenvironment during immunotherapy: a literature review

Regulatory T cells (Treg), as members of CD4+ T cells, have garnered extensive attention in the research of tumor progression. Treg cells have the function of inhibiting the immune effector cells, preventing tissue damage, and suppressing inflammation. Under the stimulation of the tumor inflammatory microenvironment (IM), the reprogramming of Treg cells enhances their suppression of immune responses, ultimately promoting tumor immune escape or tumor progression. Reducing the number of Treg cells in the IM or lowering the activity of Treg cells while preventing their reprogramming, can help promote the body's anti-tumor immune responses. This review introduces a reprogramming mechanism of Treg cells in the IM; and discusses the regulation of Treg cells on tumor progression. The control of Treg cells and the response to Treg inflammatory reprogramming in tumor immunotherapy are analyzed and countermeasures are proposed. This work will provide a foundation for downregulating the immunosuppressive role of Treg in the inflammatory environment in future tumor immunotherapy.

Role of host immunity and HBx among inactive chronic hepatitis B patients in a highly endemic region

The hepatitis B virus (HBV) infection has a wide range, from fulminant hepatitis to inactive chronic hepatitis B (ICB) infection. The present study evaluated critical factors in the outcomes of HBV infection in a highly endemic region of Iran (approximately 12% HBV positive). The expression of seven genes involved in host immunity (Foxp3, T-bet, ROR-γt, AKT, CREB, IL-28/or IFN-λ2, and IL-28R) and HBx for viral activities were evaluated using real-time PCR, TaqMan method. A total of 58 subjects were randomly chosen, including 28 ICB and 30 healthy controls (HCs) from the Esfandiar district, South Khorasan province, Iran. The expression index of Foxp3 and ROR-γt was moderately up-regulated in ICBs but did not statistically significant. T-bet expression in ICB patients was significantly higher than in HCs (p = 0.004). Furthermore, evaluating two signalling pathways in Th activation and cell survival showed that the CREB pathway was significantly up-regulated in ICB patients compared to HCs (p = 0.006), but the AKT did not differ. In innate immune responses, the IL-28/or IFN-λ2 expression in ICB patients was significantly higher than in the HCs (p = 0.02). Surprisingly, only one ICB patient disclosed HBx expression, which shows deficient virus activity in these patients. The ICB condition seems to result from host immune pressure on HBV activities, up-regulation of T-bet and IFN-λ. The high expression of CREB may prevent Kupffer's pro-inflammatory reactions in the liver. Whereas the absence of HBx expression in ICB patients and, consequently, the inactivity of HBV may also confirm such immune pressure.