Relationship between programmed cell death-1 polymorphisms and clearance of hepatitis B virus

Analysis of Programmed Cell Death-1 (PD-1) Gene Variations (re11568821 and rs41386349) in HTLV-1 Infection Using One Primer Pair and Proviral Load

About 90% of people infected with Human T lymphotropic virus type-1 (HTLV-1) virus are asymptomatic, so it can be said that the prevalence of this virus is not completely clear. During chronic infection, the expression of programmed cell death-1 (PD-1) protein increases and causes exhausted phenotype in T cells. Considering the role of host genetics and immune responses in HTLV-1 infection, in this case-control study, included 81 asymptomatic carriers (ACs) and 162 healthy controls (HCs), rs11568821 and rs41386349 polymorphisms of PD-1 gene were evaluated by Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method which investigated by one primer pair for both polymorphisms also, proviral load (PVL) measured by quantitative real-time PCR (Q-RT-PCR). The results showed that the mutant allele of rs11568821 (A) and rs41386349 (T) polymorphisms is associated with an increase in HTLV-1 infection significantly (p = 0.019 and p = 0.000 respectively). But there was no significant relationship between PVL and polymorphisms.

Immunotherapy against programmed death-1/programmed death ligand 1 in hepatocellular carcinoma: Importance of molecular variations, cellular heterogeneity, and cancer stem cells

Hepatocellular carcinoma (HCC) is a heterogeneous malignancy related to diverse etiological factors. Different oncogenic mechanisms and genetic variations lead to multiple HCC molecular classifications. Recently, an immune-based strategy using immune checkpoint inhibitors (ICIs) was presented in HCC therapy, especially with ICIs against the programmed death-1 (PD-1) and its ligand PD-L1. However, despite the success of anti-PD-1/PD-L1 in other cancers, a substantial proportion of HCC patients fail to respond. In this review, we gather current information on biomarkers of anti-PD-1/PD-L1 treatment and the contribution of HCC heterogeneity and hepatic cancer stem cells (CSCs). Genetic variations of PD-1 and PD-L1 are associated with chronic liver disease and progression to cancer. PD-L1 expression in tumoral tissues is differentially expressed in CSCs, particularly in those with a close association with the tumor microenvironment. This information will be beneficial for the selection of patients and the management of the ICIs against PD-1/PD-L1.

PD-1-Mediated PI3K/Akt/mTOR, Caspase 9/Caspase 3 and ERK Pathways Are Involved in Regulating the Apoptosis and Proliferation of CD4+ and CD8+ T Cells During BVDV Infection in vitro

Acute infection of bovine viral diarrhea virus (BVDV) is associated with immune dysfunction and can cause peripheral blood lymphopenia and lymphocyte apoptosis. Our previous study has confirmed that programmed death-1 (PD-1) blockade inhibits peripheral blood lymphocyte (PBL) apoptosis and restores proliferation and anti-viral immune functions of lymphocytes after BVDV infection in vitro. However, the immunomodulatory effects of PD-1 pathway on major PBL subsets are unclear and their underlying molecular mechanisms need to be further studied. Therefore, in this study, we examined PD-1 expression in bovine PBL subsets after BVDV infection in vitro and analyzed the effects of PD-1 blockade on the apoptosis and proliferation of CD4⁺ and CD8⁺ T cells and expression of PD-1 downstream signaling molecules. The results showed that PD-1 expression was enhanced on CD4⁺ and CD8⁺ T cells, but not on CD21⁺ B cells after cytopathic (CP) BVDV (strain NADL) and non-cytopathic (NCP) BVDV (strain KD) infection in vitro and PD-1 blockade significantly reduced the apoptosis of CD4⁺ and CD8⁺ T cells after these two strains infection. Remarkably, PD-1 blockade significantly increased the proliferation of CD4⁺ and CD8⁺ T cells after CP BVDV infection, but only significantly increased the proliferation of CD4⁺ T cells after NCP BVDV infection. In addition, we confirmed that PD-1-mediated PI3K/Akt/mTOR, caspase 9/caspase 3 and ERK pathways are involved in regulating the apoptosis and proliferation of CD4⁺ and CD8⁺ T cells during BVDV infection in vitro. Notably, ERK is involved in the regulation mechanism PD-1 mediated only when the cells are infected with CP BVDV. Our findings provide a scientific basis for exploring the molecular mechanism of immune dysfunction caused by acute BVDV infection.

Programmed cell death-1 3'-untranslated region polymorphism is associated with spontaneous clearance of hepatitis B virus infection

Hepatitis B virus (HBV)-specific CD8+ T cells play an important role in the clearance of HBV infection. Programmed cell death-1 (PD-1), an immunosuppressive molecule that regulates T-cell activation and peripheral immune tolerance, is increasingly shown to influence the outcome of HBV infection. rs10204525, a single-nucleotide polymorphism in the 3'-untranslated region (3'-UTR) of PD-1, has been associated with susceptibility and disease progression of chronic HBV infection in far-eastern patients. The aim of our study was to assess the impact of rs10204525 variation on HBV infection in Moroccan patients. A total of 236 patients with chronic HBV infection and 134 individuals with spontaneous HBV resolution were genotyped using a Taqman assay. In addition, PD-1 mRNA expression in peripheral blood nuclear cells was determined by quantitative reverse-transcription polymerase chain reaction. We found that the AA genotype is protective (odds ratio, 0.43; 95% confidence interval, 0.19 to 0.97; P = 0.038) against HBV infection. Interestingly, PD-1 messenger RNA (mRNA) expression analysis has revealed that chronic HBV carriers with GG and GA displayed higher levels of PD-1 mRNA compared with corresponding genotypes in resolved subjects (P = 0.031 and 0.014, respectively). Our data suggest that Mediterranean HBV-infected patients carrying PD-1 GG and GA genotypes at rs10204525 have high PD-1 mRNA expression and may be more prone to installation of chronicity.

Immunomodulatory effects of Tim-3 and PD-1 on chronic hepatitis B virus infection

In patients with chronic hepatitis B virus (HBV) infection, the immune cells are dysfunctional, and the immune function cannot work normally. T-cell immunoglobulin mucin-3 (Tim-3) and programmed death receptor-1 (PD-1) are overexpressed on the surface of immune cells, such as cluster of differentiation (CD)4+, CD8+ T-lymphocytes, and natural killer (NK) cells. Many studies indicate that this phenomenon is closely related to the persistence, occurrence, development, and prognosis of HBV. Tim-3 and PD-1 may be used as new immune targets for the treatment of chronic hepatitis B.