Delayed-type hypersensitivity and hepatitis B vaccine responses, in vivo markers of cellular and humoral immune function, and the risk of AIDS or death

Immune Response to Hepatitis B Virus Vaccine Among People Living With HIV: A Meta-Analysis

Background

There is conflicting evidence about whether a double dose of the hepatitis B virus (HBV) vaccine induces better immunity than the standard-dose vaccine for people living with HIV (PLWH). This study provides a meta-analysis that summarizes the efficacy of HBV vaccine regimens among HIV-infected patients, clarifying the role of particular factors such as dose and frequency of vaccination in vaccine responsiveness and highlighting the need for evidence-based practice to assess HBV vaccination among PLWH.

Methods

Randomized clinical trials (RCTs) and prospective studies reporting vaccination response rates among PLWH were found through a search of PubMed, Cochrane, and the Web of Science. The key outcome was vaccine response. A random-effects model was used to estimate the pooled response rate. Subgroup analysis was conducted to evaluate key factors and explore sources of heterogeneity. Possible biases were assessed using quality and publication bias assessment.

Results

Eligible studies included controlled trials that examined the effects of 17 interventional studies with 1,821 participants. Among PLWH who received the HBV vaccine, the pooled response rate of HBV vaccination was 71.5% (95% CI 64.0%-77.9%, p < 0.001). Compared with the standard dose (65.5%, 95% CI 53.1%-76.1%), the double dose (75.2%, 95% CI 66.2%-82.5%) was associated with a better response rate [Q(1) = 19.617, p < 0.001]. When stratified by schedule, the four-dose schedule (89.7%, 95% CI 83.1%-93.9%) had a higher response rate than the three-dose schedule (63.3%, 95% CI 56.6%-69.4%) and the difference was significant [Q(1) = 88.305, p < 0.001]. PLWH with higher CD4⁺ T-cell counts (>500 cells/mm³) at the time of vaccination had better response rates [Q(1) = 88.305, p < 0.001].

Conclusions

In this meta-analysis, the double dose of the HBV vaccine and multiple injections were associated with better immune responses than the standard HBV vaccine regimen in PLWH. Higher seroconversion rates were observed in PLWH with high CD4⁺ T-cell levels, indicating that individuals infected with HIV should receive the HBV vaccine as soon as possible after diagnosis.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/.

HIV-1 Latency and Viral Reservoirs: Existing Reversal Approaches and Potential Technologies, Targets, and Pathways Involved in HIV Latency Studies

Eradication of latent human immunodeficiency virus (HIV) infection is a global health challenge. Reactivation of HIV latency and killing of virus-infected cells, the so-called "kick and kill" or "shock and kill" approaches, are a popular strategy for HIV cure. While antiretroviral therapy (ART) halts HIV replication by targeting multiple steps in the HIV life cycle, including viral entry, integration, replication, and production, it cannot get rid of the occult provirus incorporated into the host-cell genome. These latent proviruses are replication-competent and can rebound in cases of ART interruption or cessation. In general, a very small population of cells harbor provirus, serve as reservoirs in ART-controlled HIV subjects, and are capable of expressing little to no HIV RNA or proteins. Beyond the canonical resting memory CD4⁺ T cells, HIV reservoirs also exist within tissue macrophages, myeloid cells, brain microglial cells, gut epithelial cells, and hematopoietic stem cells (HSCs). Despite a lack of active viral production, latently HIV-infected subjects continue to exhibit aberrant cellular signaling and metabolic dysfunction, leading to minor to major cellular and systemic complications or comorbidities. These include genomic DNA damage; telomere attrition; mitochondrial dysfunction; premature aging; and lymphocytic, cardiac, renal, hepatic, or pulmonary dysfunctions. Therefore, the arcane machineries involved in HIV latency and its reversal warrant further studies to identify the cryptic mechanisms of HIV reservoir formation and clearance. In this review, we discuss several molecules and signaling pathways, some of which have dual roles in maintaining or reversing HIV latency and reservoirs, and describe some evolving strategies and possible approaches to eliminate viral reservoirs and, ultimately, cure/eradicate HIV infection.

Telomere and ATM Dynamics in CD4 T-Cell Depletion in Active and Virus-Suppressed HIV Infections

CD4 T-cell depletion is a hallmark of HIV/AIDS, but the underlying mechanism is still unclear. We have recently shown that ataxia-telangiectasia-mutated (ATM) deficiency in CD4 T cells accelerates DNA damage, telomere erosion, and cell apoptosis in HIV-infected individuals on antiretroviral therapy (ART). Whether these alterations in ART-treated HIV subjects occur in vitro in HIV-infected CD4 T cells remains unknown. In this study, we employed a cellular model of HIV infection to characterize the mechanisms underlying CD4 T-cell destruction by analyzing the telomeric DNA damage response (DDR) and cellular apoptosis in highly permissive SupT1 cells, followed by the validation of our observations in primary CD4 T cells with active or drug-suppressed HIV infection. Specifically, we established an in vitro HIV T-cell culture system with viral replication and raltegravir (RAL; an integrase inhibitor) suppression, mimicking active and ART-controlled HIV infection in vivo We demonstrated that HIV-induced, telomeric DDR plays a pivotal role in triggering telomere erosion, premature T-cell aging, and CD4 T-cell apoptosis or depletion via dysregulation of the PI3K/ATM pathways. This in vitro model provides a new tool to investigate HIV pathogenesis, and our results shed new light on the molecular mechanisms of telomeric DDR and CD4 T-cell homeostasis during HIV infection.IMPORTANCE The hallmark of HIV infection is a gradual depletion of CD4 T cells, with a progressive decline of host immunity. How CD4 T cells are depleted in individuals with active and virus-suppressed HIV infection remains unclear. In this study, we employed a cellular model of HIV infection to characterize the mechanisms underlying CD4 T-cell destruction by analyzing the chromosome end (telomere) DNA damage response (DDR) and cellular apoptosis in a T-cell line (highly permissive SupT1 cells), as well as in primary CD4 T cells with active or drug-suppressed HIV infection. We demonstrated that HIV-induced telomeric DDR plays a critical role in inducing telomere loss, premature cell aging, and CD4 T-cell apoptosis or depletion via dysregulation of the PI3K/ATM pathways. This study sheds new light on the molecular mechanisms of telomeric DDR and its role in CD4 T-cell homeostasis during HIV infection.

Infectious Disease Clinical Research Program: Building the Bench

The role of physicians in the U.S. Armed Forces is diverse, encompassing a wide array of skills and responsibilities to provide superior healthcare to their patients and to advance military medicine. In addition to healthcare delivery and medical education, military physicians are engaged in public health, operational medicine, and cutting-edge medical research. Thus, clinical research is a crucial component of Graduate Medical Education (GME) and supports critical thinking (knowledge, skills, and abilities) and the development of leadership skills among U.S. military physicians. The Infectious Disease Clinical Research Program (IDCRP) education mission was established in 2005 with the overall goal of supporting the development and training of the next generation of clinical researchers in infectious diseases and related public health disciplines in the Armed Forces using several strategies, including didactic learning, mentored research, and research engagement. Through involvement in the IDCRP, infectious disease fellows, residents (e.g., surgical, internal medicine, and pediatrics), and Master of Public Health (MPH) students have continued their education and gained valuable skills related to clinical research. Trainees either conduct research with IDCRP mentors or participate in IDCRP-led practicum experiences, with research projects ranging from epidemiologic studies to microbiological assessments. Consistent with the needs of the Military Health System (MHS), and in accordance with Accreditation Council for Graduate Medical Education goals, the IDCRP provides opportunities for medical and graduate students, residents, and infectious disease fellows to conduct mentored research within the MHS, as well as gain important leadership skills in the conduct of clinical research. Overall, IDCRP continues to further infectious disease research through the support and education of the next generation of active-duty infectious disease researchers in the MHS.

ATM Deficiency Accelerates DNA Damage, Telomere Erosion, and Premature T Cell Aging in HIV-Infected Individuals on Antiretroviral Therapy

HIV infection leads to a phenomenon of inflammaging, in which chronic inflammation induces an immune aged phenotype, even in individuals on combined antiretroviral therapy (cART) with undetectable viremia. In this study, we investigated T cell homeostasis and telomeric DNA damage and repair machineries in cART-controlled HIV patients at risk for inflammaging. We found a significant depletion of CD4 T cells, which was inversely correlated with the cell apoptosis in virus-suppressed HIV subjects compared to age-matched healthy subjects (HS). In addition, HIV CD4 T cells were prone to DNA damage that extended to chromosome ends-telomeres, leading to accelerated telomere erosion-a hallmark of cell senescence. Mechanistically, the DNA double-strand break (DSB) sensors MRE11, RAD50, and NBS1 (MRN complex) remained intact, but both expression and activity of the DNA damage checkpoint kinase ataxia-telangiectasia mutated (ATM) and its downstream checkpoint kinase 2 (CHK2) were significantly suppressed in HIV CD4 T cells. Consistently, ATM/CHK2 activation, DNA repair, and cellular functions were also impaired in healthy CD4 T cells following ATM knockdown or exposure to the ATM inhibitor KU60019 in vitro, recapitulating the biological effects observed in HIV-derived CD4 T cells in vivo. Importantly, ectopic expression of ATM was essential and sufficient to reduce the DNA damage, apoptosis, and cellular dysfunction in HIV-derived CD4 T cells. These results demonstrate that failure of DSB repair due to ATM deficiency leads to increased DNA damage and renders CD4 T cells prone to senescence and apoptotic death, contributing to CD4 T cell depletion or dysfunction in cART-controlled, latent HIV infection.

Hepatitis B vaccine nonresponders: Possible mechanisms and solutions

OBJECTIVE

Hepatitis B (HBV) is a viral illness that chronically infects 240 million people worldwide, leads to liver disease, and increases risk of hepatocellular carcinoma. The HBV vaccine has decreased HBV infection, and it and the human papilloma virus vaccine are the only vaccines that prevent cancer. Despite the effectiveness of the HBV vaccine, some populations do not develop protective responses. The risk groups for poor response include those with immunosuppression or dialysis-dependent, end-stage renal disease. Five percent of normal people do not have a response. These subjects are deemed HBV "nonresponders." Multiple strategies to improve the immunogenicity of the HBV vaccine are currently being pursued, including vaccine adjuvants, recombinant vaccines, and immune enhancement via up-regulation of dendritic cells.

DATA SOURCES

PubMed was searched for peer-reviewed publications published from January 1980 to September 2017.

STUDY SELECTIONS

Studies retrieved for inclusion summarized potential mechanisms behind HBV vaccine nonresponsiveness and potential solutions.

RESULTS

The mechanisms behind HBV vaccine nonresponsiveness vary between each subject population. Many current and future strategies may provide protective immunity against HBV in each of these populations.

CONCLUSION

This review provides a background on the immunology of HBV infection, the possible immunologic mechanisms to explain HBV vaccine nonresponsiveness, current research aimed at improving vaccine effectiveness, and possible future approaches for providing nonresponders protection from HBV.

Occult hepatitis B virus infection and S gene escape mutants in HIV-infected patients after hepatitis B virus vaccination

Hepatitis B virus (HBV) vaccination is recommended for HIV patients. Despite the relative success of HBV vaccination, breakthrough infections can occur infrequently in patients, and it can be due to occult HBV infection, vaccine unresponsiveness and/or emergence of escape mutants. This study assessed the presence of occult HBV infection and S gene escape mutants in HIV-positive patients after HBV vaccination. Ninety-two HIV-positive patients were enrolled in this study, including 52 responders to HBV vaccine and 40 non-responders. All of the cases received HBV vaccine according to routine HBV vaccination protocols. The presence of HBV-DNA was determined by real-time polymerase chain reaction (PCR). In HBV-DNA positive samples, the most conserved regions of S gene sequences were amplified by nested PCR and PCR products were sequenced. Occult HBV infection was detected in two cases. Glycine to arginine mutation at residue 145 (G145R) within the ‘a’ region of the S gene was detected in one of the occult HBV infection cases who was in the non-responder group. This study showed that the prevalence of occult HBV infection and vaccine escape mutants was low in our HBV-vaccinated HIV-positive patients in both responder and non-responder groups, so there was no alarming evidence indicating breakthrough HBV infection in our vaccinated HIV-positive cases.