The co-inhibitory pathway and cellular immune imbalance in the progress of HBV infection

The Adaptive Immune Response in Hepatitis B Virus-Associated Hepatocellular Carcinoma Is Characterized by Dysfunctional and Exhausted HBV-Specific T Cells

This systematic review investigates the immunosuppressive environment in HBV-associated hepatocellular carcinoma (HCC), characterized by dysfunctional and exhausted HBV-specific T cells alongside an increased infiltration of HBV-specific CD4+ T cells, particularly regulatory T cells (Tregs). Heightened expression of checkpoint inhibitors, notably PD-1, is linked with disease progression and recurrence, indicating its potential as both a prognostic indicator and a target for immunotherapy. Nevertheless, using PD-1 inhibitors has shown limited effectiveness. In a future perspective, understanding the intricate interplay between innate and adaptive immune responses holds promise for pinpointing predictive biomarkers and crafting novel treatment approaches for HBV-associated HCC.

Immune checkpoints on T and NK cells in the context of HBV infection: Landscape, pathophysiology and therapeutic exploitation

In hepatitis B virus (HBV) infection, the interplay between the virus and the host immune system is crucial in determining the pathogenesis of the disease. Patients who fail to mount a sufficient and sustained anti-viral immune response develop chronic hepatitis B (CHB). T cells and natural killer (NK) cells play decisive role in viral clearance, but they are defective in chronic HBV infection. The activation of immune cells is tightly controlled by a combination of activating and inhibitory receptors, called immune checkpoints (ICs), allowing the maintenance of immune homeostasis. Chronic exposure to viral antigens and the subsequent dysregulation of ICs actively contribute to the exhaustion of effector cells and viral persistence. The present review aims to summarize the function of various ICs and their expression in T lymphocytes and NK cells in the course of HBV infection as well as the use of immunotherapeutic strategies targeting ICs in chronic HBV infection.

Selective downregulation of natural killer activating receptors on NK cells and upregulation of PD-1 expression on T cells in children with severe and/or recurrent Herpes simplex virus infections

Severe, recurrent or atypical Herpes simplex virus (HSV) infections are still posing clinical and diagnostic problem in clinical immunology facilities. However, the molecular background of this disorder is still unclear. The aim of this study was to investigate the expression of activating receptors on NK cells (CD16, NKp46, NKG2D, NKp80, 2B4, CD48 and NTB-A) and checkpoint molecule PD-1 on T lymphocytes and NK cells, in patients with severe and/or recurrent infections with HSV and age-matched healthy control subjects. As a result, we noticed that patients with severe and/or recurrent infection with HSV had significantly lower percentage of CD16^brightCD56^dim and higher percentage of CD16^dimCD56^bright NK cell subsets, when compared to control subjects, which may be associated with abnormal NK cell maturation during chronic HSV infection. Patients had also significantly downregulated expression of CD16 receptor on CD16^bright NK cells. The expression of activating receptors was significantly reduced on patients' NK cells - either both the percentage of NK cells expressing the receptor and MFI of its expression (NKp46, NKp80 and 2B4 on CD16^brightCD56^dim cells and NKp46 on CD16^dimCD56^bright cells) or only MFI (NKG2D on both NK cell subsets). It should be noted that the reduction of receptor expression was limited to NK cells, since there was no differences in the percentage of receptor-positive cells or MFI on T cells. However, NTB-A receptor was the only one which expression was not only simultaneously changed in patients' NK and T cells, but also significantly upregulated on CD16^dimCD56^bright NK cell and CD8⁺ cell subsets. Patients had also upregulated proportion of CD4⁺ T cells expressing PD-1. Thus, we suggest that an increased percentage of PD-1⁺ cells may represent an independent indirect mechanism of downregulation of antiviral response, separate from the reduction of NK cell activating receptors expression. Altogether, our studies indicate two possible mechanisms which may promote perpetuation of HSV infection: 1) selective inhibition of activating receptors on NK cells, but not on T cells, and 2) upregulation of checkpoint molecule PD-1 on CD4⁺ T cells.

HBV upregulated triggering receptor expressed on myeloid cells-1 (TREM-1) expression on monocytes participated in disease progression through NF-Kb pathway

The triggering receptor expressed on myeloid cells-1 (TREM-1) signal is related to the continuous amplification of inflammatory pathway. However, it is not clear whether and how HBV can regulated the expression of TREM-1 on monocyte participated in the progression of liver disease. Here, we showed that the expression of TREM-1 on monocyte subsets were increased significantly in HBV related liver cirrhosis group compared with chronic infected group and healthy control group. HBsAg and HBeAg could up-regulated TREM-1 on monocyte by NF-KB pathway, and at least last for 72 h. Increased TREM-1 on monocyte might associated with high level of inflammatory cytokine (TNF-a, IL-1β and IL-6) and the activation of LX-2 cells. Bioinformatics analysis showed that the high expression of TREM-1 was related to the poor prognosis of hepatocellular carcinoma (HCC). The level of TREM-1 might help to predict the progression of HBV infected liver disease and treat target to prevent fibrosis progression.

Correlation of CpG methylation of the Pdcd1 gene with PD-1 expression on CD8+ T cells and medical laboratory indicators in chronic hepatitis B infection

BACKGROUND

The negative signal provided by some co-inhibitory factors such as programmed cell death-1 (PD-1) has been associated with chronic hepatitis B (CHB) infection induced-T cell exhaustion, although the correlation of CpG methylation of the Pdcd1 gene with PD-1 expression and medical laboratory indicators in CHB infection has not yet been elucidated.

METHODS

Blood samples from 20 CHB infection patients and 20 spontaneous clearance (SC) patients were collected. Percentages of PD-1-positive CD8⁺ T cells were analyzed by flow cytometry. The percentage of CpG methylation at the Pdcd1 locus was analyzed by bisulfite sequencing. Student's t test, Pearson and Spearman's correlation, and Mann-Whitney tests were used in the statistical analysis.

RESULTS

Percentages of PD-1-positive CD8⁺ T cells in peripheral blood T cells were significantly higher in CHB patients than in the SC group (p < 0.001). The methylation level of Pdcd1 was significantly lower in CHB patients (p < 0.001) and the methylation level of Pdcd1 was negatively correlated with PD-1 expression level in CD8⁺ T cells (p < 0.001) and hepatitis-B surface antigen (HBsAg) (p < 0.001).

CONCLUSIONS

The results of the present study suggest that Pdcd1 methylation is correlated with PD-1 expression on CD8⁺ T cells and correlated with HBsAg and alanine aminotransferase. The results may provide new ideas regarding anti-PD-1 inhibitors, and epigenetic regulators such as demethylation inhibitors could represent more successful therapeutic strategies in hepatitis B infection patients.

BTLA/HVEM Signaling: Milestones in Research and Role in Chronic Hepatitis B Virus Infection

B- and T-lymphocyte attenuator (BTLA) is an immune-regulatory receptor, similar to CTLA-4 and PD-1, and is mainly expressed on B-, T-, and all mature lymphocyte cells. Herpes virus entry mediator (HVEM)-BTLA plays a critical role in immune tolerance and immune responses which are areas of intense research. However, the mechanisms of the BTLA and the BTLA/HVEM signaling pathway in human diseases remain unclear. This review describes the research milestones of BTLA and HVEM in chronological order and their role in chronic HBV infection.

Circulating soluble programmed death-1 levels may differentiate immune-tolerant phase from other phases and hepatocellular carcinoma from other clinical diseases in chronic hepatitis B virus infection

Programmed death-1 (PD-1) is involved in the immune dysfunction of hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC). This study analyzed the association of circulating soluble PD-1 (sPD-1) levels with the phases and clinical diseases in chronic HBV infection. Serum sPD-1 levels were determined by enzyme linked immunosorbent assay in patients with different phases and liver diseases of chronic HBV infection. The sPD-1 levels in patients with chronic HBV infection were significantly elevated compared with HBV infection resolvers or healthy controls. According to phases, sPD-1 level in immune-tolerant phase (IT) was significantly lower than in other phases. Multivariate analysis showed that sPD-1 was an independent factor associated with IT. Area under the receiver operating characteristic (ROC) curves (AUC) showed that sPD-1 was significantly discriminative of IT from other phases with a cut-off of 1.535 ng/mL (AUC, 0.984; P<0.001). According to clinical diseases, sPD-1 level in HBV-related HCC was significantly higher than in other clinical diseases. Multivariate analysis showed that sPD-1 was an independent factor associated with HCC. The sPD-1 was significantly discriminative of HCC from other clinical diseases with a cut-off of 6.058 ng/mL (AUC, 0.962; P<0.001). The sPD-1 levels were significantly associated with HCC patients’ overall survival. HCC resection resulted in remarkable reduction in sPD-1 levels. These results demonstrate the involvement of sPD-1 in the disease course of chronic HBV infection and indicate the potential to apply sPD-1 as a biomarker for differentiating IT from other phases and HCC from other disease conditions in chronic HBV infection.

Circulating microRNAs as potential biomarkers of HBV infection persistence

OBJECTIVES

To investigate different microRNA (miRNA) expression profile in patients of hepatitis B virus (HBV) infection compared with virus spontaneous clearance ones, and try to find new biomarker for diagnosis and treatment assessment.

METHODS

miRNA expression profiling was analyzed in patients with HBV infection and patients with virus spontaneous clearance by Affymetrix Gene Chip miRNA 4.0 Arrays. The differently expressed miRNAs, as verified by RT-PCR, were analyzed and compared with each other in the two groups of patients.

RESULTS

Significant difference was found in the expression of miR-29b, miR-34, miR-4485, miR-3180, miR-125, miR-330-3p, miR-1468 in spontaneous clearance group and CHB group. miR-29b, miR-34, miR-4485 was significantly increased in CHB group, while miR-125, miR-330-3p, miR-1468, miR-3180 was significantly decreased. Correlation analysis indicate only miR-29b was positive correlation with HBsAg.

CONCLUSIONS

These results indicated above miRNAs may be associated with HBV infection persistence, and provided us new ideas for finding potential biomarkers.