Ubiquitin-hepatitis B core antigen-cytoplasmic transduction peptide enhances HBV-specific humoral and CTL immune responses in vivo

The downregulation of Tapasin in dendritic cell regulates CD8+ T cell autophagy to hamper hepatitis B viral clearance in the induced pluripotent stem cell-derived hepatocyte organoid

Tapasin, a crucial molecular chaperone involved viral antigen processing and presentation, plays an important role in antivirus immunity. However, its impact on T cell differentiation in the context of virus clearance remains unclear. In this study, we employed induced pluripotent stem cells to differentiate into hepatocyte-like cell, which were subsequently inserted to the inverted colloidal crystal scaffolds, thus establishing a hepatocyte organoid (HO). By inoculating hepatitis B virus (HBV) particles in the system, we successfully engineered a robust in vitro HBV infection model for at least 3 weeks. Furthermore, we aimed to explore the effects of lentivirus-mediated short hairpin RNA (shRNA) targeting human Tapasin on the differentiation and antiviral function of CD8+ T cells. Specifically, we transfected dendritic cells (DCs) with Tapasin-shRNA and cocultured with T cells. The results demonstrated that Tapasin-shRNA transfected DCs effectively suppressed T cell proliferation and impeded HBV-specific cytotoxic T lymphocyte responses. Our investigation also revealed the role of mTOR pathway activation in reducing autophagy activity within CD8+ T cells. Expressions of autophagy-related proteins, beclin-1, LC3II/LC3I were decreased and PI3K/AKT/mTOR activity was increased in Tapasin-shRNA group. Collectively, our findings elucidate that shRNA targeting the Tapasin gene within DCs inhibits T cell differentiation by reducing autophagy activity to hamper viral clearance in the HBV-infected HO.

Elicitation of integrated immunity in mice by a novel pneumococcal polysaccharide vaccine conjugated with HBV surface antigen

The conjugation of polysaccharides with an effective carrier protein is critical for the development of effective bacterial polysaccharide vaccines. Therefore, the identification and optimization of carrier proteins to induce an effective immune response is necessary for developing a combined vaccine. In the current study, we utilized hepatitis B virus surface antigen (HBsAg) as a novel carrier protein combined with a capsular polysaccharide molecule to develop a new pneumococcal conjugated vaccine. The specific antibodies and T cell immune response against the capsular polysaccharide and HBsAg in the mice immunized with this conjugated vaccine were evaluated. In addition, the unique gene profiles of immune cells induced by this conjugated vaccine in the immunized mice were analyzed. Our results demonstrated that the vaccine consisting of pneumonia type 33 F capsular polysaccharide (Pn33Fps) conjugated with HBsAg can induce strong specific immune responses against both antigens in vivo in immunized mice. Furthermore, the conjugated vaccine induced higher expression of genes related to the activation of immunity and higher antibody titers against Pn33Fps and HBsAg in mice than those obtained via vaccination with a single antigen. Analyses of the dynamic expression changes in immunity-related genes in mice immunized with Pn33Fps_HBs, Pn33Fps, or HBsAg indicated the potent immunogenicity of the conjugated vaccine. In addition, a pathological evaluation of the organs from immunized mice further suggested that the conjugated vaccine is safe. Together, these results indicate that a conjugated vaccine consisting of Pn33Fps with HBsAg is a novel and effective vaccine.

Binding of a C-type lectin's coiled-coil domain to the Domeless receptor directly activates the JAK/STAT pathway in the shrimp immune response to bacterial infection

C-type lectins (CTLs) are characterized by the presence of a C-type carbohydrate recognition domain (CTLD) that by recognizing microbial glycans, is responsible for their roles as pattern recognition receptors in the immune response to bacterial infection. In addition to the CTLD, however, some CTLs display additional domains that can carry out effector functions, such as the collagenous domain of the mannose-binding lectin. While in vertebrates, the mechanisms involved in these effector functions have been characterized in considerable detail, in invertebrates they remain poorly understood. In this study, we identified in the kuruma shrimp (Marsupenaeus japonicus) a structurally novel CTL (MjCC-CL) that in addition to the canonical CTLD, contains a coiled-coil domain (CCD) responsible for the effector functions that are key to the shrimp's antibacterial response mediated by antimicrobial peptides (AMPs). By the use of in vitro and in vivo experimental approaches we elucidated the mechanism by which the recognition of bacterial glycans by the CTLD of MjCC-CL leads to activation of the JAK/STAT pathway via interaction of the CCD with the surface receptor Domeless, and upregulation of AMP expression. Thus, our study of the shrimp MjCC-CL revealed a striking functional difference with vertebrates, in which the JAK/STAT pathway is indirectly activated by cell death and stress signals through cytokines or growth factors. Instead, by cross-linking microbial pathogens with the cell surface receptor Domeless, a lectin directly activates the JAK/STAT pathway, which plays a central role in the shrimp antibacterial immune responses by upregulating expression of selected AMPs.

Vaccination with ubiquitin-hepatitis B core antigen-cytoplasmic transduction peptide enhances the hepatitis B virus-specific cytotoxic T-lymphocyte immune response and inhibits hepatitis B virus replication in transgenic mice

Chronic hepatitis B virus (HBV) infection is characterized by functionally impaired type 1 T-helper cell (Thl) immunity and poor HBV‑specific T‑cell responses. Ubiquitin (Ub), a highly conserved small regulatory protein, commonly serves as a signal for target proteins that are recognized and degraded in proteasomes. The rapid degradation of Ub‑mediated antigens results in efficient stimulation of cell‑mediated immune responses. Thus, the Ub‑HBV core antigen (HBcAg)‑cytoplasmic transduction peptide (CTP) fusion protein was designed for specific delivery of a foreign modified antigen to the cytoplasm of antigen‑presenting cells. HBV transgenic mice were used to determine whether Ub‑HBcAg‑CTP would restore HBV‑specific immune responses and anti‑viral immunity in these animals. The results demonstrated that synthesized Ub‑HBcAg‑CTP not only significantly increased the levels of interleukin‑2 and interferon (IFN)‑γ compared with those in the HBcAg‑CTP, IFN‑α, Ub‑HBcAg, HBcAg and phosphate‑buffered saline groups, but additionally induced the highest IFN‑γ+ CD8+ T‑cell numbers and HBV‑specific cytotoxic T lymphocyte (CTL) responses, indicating a strong immune response. In addition, enhancement of specific CTL activity provoked by the fusion protein reduced hepatitis B surface antigen (HBsAg) and HBV DNA serum levels and diminished the expression of HBsAg and HBcAg in liver tissue of HBV transgenic mice, suggesting that there was a therapeutic effect. In conclusion, the present study provided evidence that Ub‑HBcAg‑CTP activated the Th1‑dependent immunity, triggered functional T cell responses and subsequently inhibited viral replication in HBV transgenic mice. These observations suggested that the fusion protein may represent an innovative and promising candidate for active immunotherapy during chronic and persistent HBV.

Protective effect of platycodin D on liver injury in alloxan-induced diabetic mice via regulation of Treg/Th17 balance

Platycodin D is a major pharmacological constituent of Platycodi Radix with immunomodulatory activity. The present study was designed to investigate how platycodin D (PLD) reveals liver injury in diabetic mice and its mechanism. Fifty mice were divided into five groups randomly: control group, model group, rosiglitazone (ROG, 10 mg/kg) group, PLD (50 mg/kg) group, and PLD (100 mg/kg) group. Diabetes was induced with the injection of alloxan monohydrate (150 mg/kg) subcutaneously, and animals with blood glucose level of ≥250 mg/dl were considered as diabetic mice. After the first day of diabetes induction, the treatments were performed for 8 weeks. Then the animals were anaesthetized, and blood and liver samples were also collected for further assay. PLD significantly decreased the serum levels of glucose, insulin, interleukin-6 (IL-6), interleukin-1β, tumor necrosis factor-α (TNF-α), and interleukin (IL)-17A and increased IL-10 level in serum. PLD effectively downregulated aspartate transaminase (AST), alanine aminotransferase (ALT), total cholesterol (TC), and triglycerides (TG) in liver. PLD also attenuated liver histological change. In addition, PLD significantly attenuated IL-17A and IL-10 levels in vitro, flow cytometry (FCM) studies also showed that PLD remarkably inhibited Th17 cells and significantly increased Treg cells in liver tissues and spleen cells. Western blot demonstrated PLD inhibited the phosphorylation of JAK and STAT-3 and the expression of RORγt and increased the expression of Foxp3. The findings showed that PLD exerts beneficial effects on alloxan-induced liver injury in mice.