CD4+ T Cells Play a Critical Role in Microbiota-Maintained Anti-HBV Immunity in a Mouse Model.
ABSTRACT: The ability of the host to clear hepatitis B virus (HBV) is closely correlated to the establishment of commensal microbiota. However, how microbiota affects anti-HBV immunity is still unclear. Using a well-known hydrodynamical HBV transfection mouse model and treatment with antibiotics (Atb), we explored the change in adaptive immunity (CD4+ cells, germinal center B cells and anti-HBs Ab). In our setting, normal mice exhibited complete clearance of HBV within 6 weeks post-hydrodynamic injection (HDI) of HBV-containing plasmid, whereas Atb-treated mice lost this capacity, showing high serum level of hepatitis B surface antigen (HBsAg) without hepatitis B surface antibodies (anti-HBs), similar as what happened in Rag1 -/- mice or CD4 -/- mice, suggesting that microbiota may influence the function of CD4+ T cells. Furthermore, the numbers of splenic and hepatic effector CD4+ T cells (CD44hiCD62L-CD4+ T cells) both decreased with impaired function (IFN-? synthesis), resulting in lower frequency of germinal center B cells and CD4+ follicular helper T cells, and impaired anti-HBs production. We further tried to find the bacterial species responsible for maintaining anti-HBV immunity, and found that each antibiotic alone could not significantly influence HBV clearance compared to antibiotic combination, suggesting that global commensal microbial load is critical for promoting HBV clearance. We also confirmed that TLRs (e.g., TLR2, 4, 9) are not major players in immune clearance of HBV using their agonists and knock-out mice. These results suggest that commensal microbiota play an important role in maintaining CD4+ T cell immunity against HBV infection.
Project description:BACKGROUND:Hepatitis B virus (HBV) persistently infected about 250 million people worldwide, and a curative treatment remains an unmet medical need. Among many approaches to treat chronic hepatitis B (CHB), therapeutic vaccines have been developed for two decades, but none have yielded promising results in clinical trials. Therefore, dissection of HBV clearance mechanisms during therapeutic vaccination in appropriate models, which could give rise to new curative therapies, is urgently needed. Growing evidence indicates that prolonged and intensive exposure of antigen-specific T cells to viral antigens is a major cause of T cell exhaustion, and decreases anti-HBV immunity efficacy of therapeutic vaccination. HBV X protein (HBx) is expressed at low levels, and the understanding of its immunogenicity and potential in therapeutic CHB vaccines is limited. METHODS:HBV genome sequences from CHB patients were cloned into a pAAV plasmid backbone and transfected into immunocompetent mouse hepatocytes through hydrodynamic injection. Mice carrying >?500?IU/mL serum HBV surface antigen (HBs) for more than 4?weeks were considered HBV carriers mimicking human CHB and received 3 doses of weekly HBx vaccine by subcutaneous immunization. Serum HBV clearance was evaluated by monitoring serum HBs and HBV-DNA titers. Residual HBV in the liver was evaluated by western blotting for HBV core antigen. The splenic antigen-specific T cell response was quantified by a 15-mer overlapping peptide-stimulated interferon-? enzyme-linked immunospot assay. Blood and hepatic immune cells were quantified by flow cytometric analysis. RESULTS:Our HBx-based vaccine induced systemic HBx-specific CD4+ and CD8+ T cell responses in HBV carrier mice and demonstrated significant HBs and HBV-DNA elimination. The protective effect persisted for at least 30?days without additional booster immunization. Different infiltrating myeloid cell subsets, each with distinctive roles during immune-mediated HBV clearance, were found in the liver of vaccinated mice. During vaccine therapy, inflammatory monocyte depletion resulted in sustained HBV clearance inhibition, whereas phagocytic monocyte-derived macrophage and Kupffer cell elimination resulted in only transient inhibition of vaccine-induced HBV clearance. CONCLUSIONS:We report the potential role of HBx as a major immunogen in an HBV therapeutic vaccine and the significance of a liver-infiltrating monocyte subset during hepatic viral clearance.
Project description:INTRODUCTION:Achieving functional cure of chronic HBV infection (Hepatitis B surface antigen [HBsAg] clearance, eventually followed by acquisition of anti-hepatitis B surface antigen [Anti-HBs]) in individuals with HIV and HBV infections is a rare event. In this setting, factors related to HBV cure have not yet been fully characterized. METHODS:HIV-infected individuals with chronic HBV infection enrolled in the French Dat'AIDS cohort (NCT02898987), who started combined antiretroviral (cART)-anti-HBV treatment were retrospectively analyzed for HBsAg loss and Anti-HBs seroconversion. RESULTS:Overall, 1419 naïve-subjects received three different cART-anti-HBV treatment schedule: (1) 3TC or FTC only (n = 150), (2) TDF with or without 3TC or FTC (n = 489) and (3) 3TC or FTC as first line followed by adding/switching to TDF as second line (n = 780). Individuals were followed-up for a median of 89 months (IQR, 56-118). HBV-DNA was < 15 IU/mL in 91% of individuals at the end of the follow-up. Overall, 97 individuals cleared HBsAg (0.7/100 patient-years), of whom, 67 seroconverted for Anti-HBs (0.5/100 patient-years). A high CD4 nadir, a short delay between HBV diagnosis and treatment, a longer time on HBV therapy, an African origin and TDF-based therapy were independent predictors of HBsAg clearance (Probability of odds ratio [OR]>1, >95%) suggested by Bayesian analysis. Also, TDF-based regimen as first line (OR, 3.03) or second line (OR, 2.95) increased rates of HBsAg clearance compared to 3TC or FTC alone, with a 99% probability. CONCLUSIONS:HBsAg clearance rate was low in HIV-HBV co-infected cART-anti-HBV treated individuals, but was slightly improved on TDF-based regimen.
Project description:A unique feature of hepatitis B virus (HBV) infection in humans is that viral clearance heavily depends on the age of exposure. However, the reason for this remains unclear. Here we show that gut microbiota contribute to the age dependence of HBV immunity in a hydrodynamic transfection mouse model. Although adult (12-wk-old) C3H/HeN mice cleared HBV within 6 wk postinjection (wpi), their young (6-wk-old) counterparts remained HBV-positive at 26 wpi. Sterilization of gut microbiota from 6 to 12 wk of age using antibiotics prevented adult mice from rapidly clearing HBV. Young mice with the Toll-like-receptor (TLR) 4 mutation (C3H/HeJ) exhibited rapid HBV clearance. The results suggest that an immuno-tolerating pathway to HBV prevailed in young mice, before the establishment of gut bacteria, through a TLR4-dependent pathway and that the maturation of gut microbiota in adult mice stimulated liver immunity, resulting in rapid HBV clearance.
Project description:BACKGROUND & AIMS:Infection with hepatitis B virus (HBV) can be prevented by vaccination with HB surface (HBs) antigen, which induces HBs-specific antibodies and T cells. However, the duration of vaccine-induced protective immunity is poorly defined for health care workers who were vaccinated as adults. METHODS:We investigated the immune mechanisms (antibody and T-cell responses) of long-term protection by the HBV vaccine in 90 health care workers with or without occupational exposure to HBV, 10-28 years after vaccination. RESULTS:Fifty-nine of 90 health care workers (65%) had levels of antibodies to HBs antigen above the cut-off (>12 mIU/mL) and 30 of 90 (33%) had HBs-specific T cells that produced interferon-gamma. Titers of antibodies to HBs antigen correlated with numbers of HBs-specific interferon-gamma-producing T cells, but not with time after vaccination. Although occupational exposure to HBV after vaccination did not induce antibodies to the HBV core protein (HBcore), the standard biomarker for HBV infection, CD4(+) and CD8(+) T cells against HBcore and polymerase antigens were detected. Similar numbers of HBcore- and polymerase-specific CD4(+) and CD8(+) T cells were detected in health care workers with occupational exposure to HBV and in patients who acquired immunity via HBV infection. Most of the HBcore- and polymerase-specific T cells were CD45RO(+)CCR7(-)CD127(-) effector memory cells in exposed health care workers and in patients with acquired immunity. In contrast, most of the vaccine-induced HBs-specific T cells were CD45RO(-)CCR7(-)CD127(-) terminally differentiated cells. CONCLUSIONS:HBs antigen vaccine-induced immunity protects against future infection but does not provide sterilizing immunity, as evidenced by HBcore- and polymerase-specific CD8(+) T cells in vaccinated health care workers with occupational exposure to HBV. The presence of HBcore- and HBV polymerase-specific T-cell responses is a more sensitive indicator of HBV exposure than detection of HBcore-specific antibodies.
Project description:Commensal microbiota are well known to play an important role in antiviral immunity by providing immune inductive signals; however, the consequence of dysbiosis on antiviral immunity remains unclear. We demonstrate that dysbiosis caused by oral antibiotic treatment directly impairs antiviral immunity following viral infection of the vaginal mucosa. Antibiotic-treated mice succumbed to mucosal herpes simplex virus type 2 infection more rapidly than water-fed mice, and also showed delayed viral clearance at the site of infection. However, innate immune responses, including type I IFN and proinflammatory cytokine production at infection sites, as well as induction of virus-specific CD4 and CD8 T-cell responses in draining lymph nodes, were not impaired in antibiotic-treated mice. By screening the factors controlling antiviral immunity, we found that IL-33, an alarmin released in response to tissue damage, was secreted from vaginal epithelium after the depletion of commensal microbiota. This cytokine suppresses local antiviral immunity by blocking the migration of effector T cells to the vaginal tissue, thereby inhibiting the production of IFN-?, a critical cytokine for antiviral defense, at local infection sites. These findings provide insight into the mechanisms of homeostasis maintained by commensal bacteria, and reveal a deleterious consequence of dysbiosis in antiviral immune defense.
Project description:Hepatic macrophages play a central role in disease pathogenesis during hepatitis B virus (HBV) infection. Our previous study found that CD205+ macrophages in the liver of hepatitis B surface antigen transgenic (HBs-Tg) mice increased significantly compared with those in wild-type mice, and these increased CD205+ macrophages were involved in CpG-oligodeoxynucleotide-induced liver injury in HBs-Tg mice. Here, we analysed the phenotype and function of CD205+ macrophages derived from the liver of HBs-Tg mice and patients with chronic hepatitis B (CHB). We found that HBs-Tg mice-derived hepatic macrophages produced larger amounts of pro-inflammatory cytokines, including IL-6, IL-12, TNF-?, and of the anti-inflammatory cytokine IL-10 after stimulation with CpG-oligodeoxynucleotides or commensal bacteria DNA than B6 mice-derived hepatic macrophages. Furthermore, hepatic CD205+ macrophages from HBs-Tg mice showed an activated phenotype and expressed higher levels of inflammatory cytokine genes, chemokine genes, and phagocytosis-related genes than hepatic CD205- macrophages. In addition, CD205+ macrophages displayed an inflammatory phenotype and were increased in the liver of patients with CHB compared with those in healthy controls. Our data suggest that hepatic CD205+ macrophages are a unique pro-inflammatory subset observed during HBV infection. Thus, development of intervention targeting these cells is warranted for immunotherapy of HBV-induced liver diseases.
Project description:A variety of amino acid substitutions, such as K122I and G145R, have been identified around or within the a determinant of hepatitis B surface antigen (HBsAg), impair HBsAg secretion and antibody binding, and may be responsible for immune escape in patients. In this study, we examined how different substitutions at amino acid positions 122 and 145 of HBsAg influence HBsAg expression, secretion, and recognition by anti-HBs antibodies. The results showed that the hydrophobicity, the presence of the phenyl group, and the charges in the side chain of the amino acid residues at position 145 reduced HBsAg secretion and impaired reactivity with anti-HBs antibodies. Only the substitution K122I at position 122 affected HBsAg secretion and recognition by anti-HBs antibodies. Genetic immunization in mice demonstrated that the priming of anti-HBs antibody response was strongly impaired by the substitutions K122I, G145R, and others, like G145I, G145W, and G145E. Mice preimmunized with wild-type HBsAg (wtHBsAg) or variant HBsAg (vtHBsAg) were challenged by hydrodynamic injection (HI) with a replication-competent hepatitis B virus (HBV) clone. HBsAg persisted in peripheral blood for at least 3 days after HI in mice preimmunized with vtHBsAg but was undetectable in mice preimmunized with wtHBsAg, indicating that vtHBsAgs fail to induce proper immune responses for efficient HBsAg clearance. In conclusion, the biochemical properties of amino acid residues at positions 122 and 145 of HBsAg have a major effect on antigenicity and immunogenicity. In addition, the presence of proper anti-HBs antibodies is indispensable for the neutralization and clearance of HBsAg during HBV infection.
Project description:The capacity of toll-like receptor (TLR) 7/8 agonist-conjugated hepatitis B virus (HBV) proteins (HBV-Ag) to overcome established hepatitis B surface antigen (HBsAg)-specific immune tolerance was explored.A TLR7/8 agonist, CL097, was conjugated with alum-absorbed HBsAg and hepatitis B core antigen (HBcAg), as confirmed by ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF MS). Mice from two independently generated HBV-transgenic (HBV-Tg) colonies, C57BL/6J-TgN (AlblHBV) 44Bri/J mice and C57BL/6-HBV-1.3 genome-eq mice, were immunized with CL097-conjugated HBV-Ag every 2 weeks, four times.After immunization, 8/11 (72.7%) of the AlblHBV mice and 10/13 (76.9%) of the HBV-1.3 genome-eq mice generated serum detectable antibodies against HBsAg (anti-HBs). HBsAg-specific interferon gamma (IFN-?)-producing CD4(+) and CD8(+) T-cells were detected in splenocytes from these mice. Naïve normal mice receiving splenocytes from the mice immunized with CL097-conjugated HBV-Ag generated immediate recall immune responses, e.g., the mice that received CD4(+)CD25(+)-depleted splenocytes generated anti-HBs on day 3 after HBsAg challenge while those receiving cells from sham-immunized mice did not.Immunization with CL097-conjugated HBV-Ag reversed immune tolerance in HBV-Tg mice and induced antigen-specific immune responses. TLR7/8 agonists appear to be potent adjuvants for the induction of antigen-specific Th1 responses in an immune tolerant state.
Project description:Obesity and cirrhosis are associated with poor hepatitis B virus (HBV) vaccine responses, but vaccine efficacy has not been assessed in nonalcoholic fatty liver disease (NAFLD). Sixty-eight HBV-naïve adults with NAFLD were enrolled through the Canadian HBV network and completed three-dose HBV or HBV/HAV vaccine (Engerix-B<sup>®</sup>, or Twinrix<sup>®</sup>, GlaxoSmithKline). Anti-HBs titers were measured at 1-3 months post third dose. In 31/68 subjects enrolled at the coordinating-site, T-cell proliferation and follicular T-helper cells (pTFH) were assessed using PBMC. Immune response was also studied in NAFLD mice. NAFLD patients were stratified as low-risk-obesity, BMI?<?35 (N?=?40) vs. medium-high-risk obesity, BMI?>?35 (N?=?28). Anti-HBs titers were lower in medium/high-risk obesity, 385 IU/L?±?79 vs. low-risk obesity class, 642 IU/L?±?68.2, p?=?0.02. High-risk obesity cases, N?=?14 showed lower vaccine-specific-CD3+ CD4+ T-cell response compared to low-risk obesity patients, N?=?17, p?=?0.02. Low vaccine responders showed dysfunctional pTFH. NAFLD mice showed lower anti-HBs levels and T-cell response vs. controls. In conclusion, we report here that obese individuals with NAFLD exhibit decreased HBV vaccine-specific immune responses.
Project description:Vaccination is the appropriate measure to protect military personnel against the hepatitis B virus (HBV) infection. Testing the military personnel for anti-HBs levels after vaccination is vital in re-vaccinating those that have not developed protective immunity. The aim of the current study was to determine the immunity in a group of vaccinated Sri Lankan military personnel (n?=?150; age?=?26-44 years) following a complete course of hepatitis B virus surface antigen (HBsAg) vaccination by assessing the antibodies against HBsAg (anti-HBs) levels. Three months after the last dose of the vaccination, blood samples were collected from the study population and tested for anti-HBs levels using a commercially available ELISA. Of the 150 military service men tested, 139 (92.67%) had anti-HBs levels higher than 10 mIU/mL, WHO approved levels for protective immunity against HBV infection. Of the 139 that had sufficient anti-HBs levels, 24% (36/150) had anti-HBs levels between 10 and 100 mIU/mL and 68.67% (103/150) had anti-HBs levels?>?100 mIU/mL. Overall, 7.33% (11/150) participants had anti-HBs levels?<?10 mIU/mL. Sero-conversion to?>?10 mIU/mL anti-HBs was more than 90% in those that were less than 40 years of age and it was less than 90% in those that were more than 40 years of age.