Decreased Survival of B Cells of HIV-viremic Patients Mediated by Altered Expression of Receptors of the TNF Superfamily

Human immunodeficiency virus (HIV) infection leads to numerous perturbations of B cells through mechanisms that remain elusive. We performed DNA microarray, phenotypic, and functional analyses in an effort to elucidate mechanisms of B cell perturbation associated with ongoing HIV replication. 42 genes were up-regulated in B cells of HIV-viremic patients when compared with HIV-aviremic and HIV-negative patients, the majority of which were interferon (IFN)-stimulated or associated with terminal differentiation. Flow cytometry confirmed these increases and indicated that CD21low B cells, enhanced in HIV-viremic patients, were largely responsible for the changes. Increased expression of the tumor necrosis factor (TNF) superfamily (TNFSF) receptor CD95 correlated with increased susceptibility to CD95-mediated apoptosis of CD21low B cells, which, in turn, correlated with HIV plasma viremia. Increased expression of BCMA, a weak TNFSF receptor for B lymphocyte stimulator (BLyS), on CD21low B cells was associated with a concomitant reduction in the expression of the more potent BLyS receptor, BAFF-R, that resulted in reduced BLyS binding and BLyS-mediated survival. These findings demonstrate that altered expression of genes associated with IFN stimulation and terminal differentiation in B cells of HIV-viremic patients lead to an increased propensity to cell death, which may have substantial deleterious effects on B cell responsiveness to antigenic stimulation

Global Burden of Atherosclerotic Cardiovascular Disease in People Living with the Human Immunodeficiency Virus:A Systematic Review and Meta-Analysis

Background: With advances in antiretroviral therapy, most deaths in people with HIV are now attributable to noncommunicable illnesses, especially cardiovascular disease. We determine the association between HIV and cardiovascular disease, and estimate the national, regional, and global burden of cardiovascular disease attributable to HIV. Methods: We conducted a systematic review across 5 databases from inception to August 2016 for longitudinal studies of cardiovascular disease in HIV infection. A random-effects meta-analysis across 80 studies was used to derive the pooled rate and risk of cardiovascular disease in people living with HIV. We then estimated the temporal changes in the population-attributable fraction and disability-adjusted life-years (DALYs) from HIV-associated cardiovascular disease from 1990 to 2015 at a regional and global level. National cardiovascular DALYs associated with HIV for 2015 were derived for 154 of the 193 United Nations member states. The main outcome measure was the pooled estimate of the rate and risk of cardiovascular disease in people living with HIV and the national, regional, and global estimates of DALYs from cardiovascular disease associated with HIV. Results: In 793 635 people living with HIV and a total follow-up of 3.5 million person-years, the crude rate of cardiovascular disease was 61.8 (95% CI, 45.8–83.4) per 10 000 person-years. In comparison with individuals without HIV, the risk ratio for cardiovascular disease was 2.16 (95% CI, 1.68–2.77). Over the past 26 years, the global population–attributable fraction from cardiovascular disease attributable to HIV increased from 0.36% (95% CI, 0.21%–0.56%) to 0.92% (95% CI, 0.55%–1.41%), and DALYs increased from 0.74 (95% CI, 0.44–1.16) to 2.57 (95% CI, 1.53–3.92) million. There was marked regional variation with most DALYs lost in sub-Saharan Africa (0.87 million, 95% CI, 0.43–1.70) and the Asia Pacific (0.39 million, 95% CI, 0.23–0.62) regions. The highest population-attributable fraction and burden were observed in Swaziland, Botswana, and Lesotho. Conclusions: People living with HIV are twice as likely to develop cardiovascular disease. The global burden of HIV-associated cardiovascular disease has tripled over the past 2 decades and is now responsible for 2.6 million DALYs per annum with the greatest impact in sub-Saharan Africa and the Asia Pacific regions. Clinical Trial Registration: URL: https://www.crd.york.ac.uk/prospero. Unique identifier: CRD42016048257

Defective cytotoxic T lymphocyte function in HIV infection

The primary objective of this thesis is to determine whether cytotoxic T lymphocytes (CTL) detectable against CD4⁻ lymphocytes in vitro act in vivo to promote CD4⁻ depletion and thereby contributing to immune dysfunction and disease progression in HIV-I infected individuals. During this study, the relationship between the level of CTL activity against CD4 lymphocytes and disease progression was assessed by carrying out a series of in vitro experiments in a HIV-positive cohort of ∼70 individuals. -- It is well established that CTL use clonotypic T cell receptors (TCR) associated with the invariant CD3 signalling complex, to recognize antigenic peptides bound to major histocompatibility complex (MHC) molecules on the target cells. Since P815 cells express an FcR and Fas antigen, IgG anti-CD3 antibodies can trigger non-specific killing of P815 cells by a variety of effector cells. Comparable inhibition of cellular cytotoxicity against P815 cells by Jo-2 or by cycloheximide, a protein synthesis inhibitor preventing Fas ligand induction, confirmed that the different levels of killing of Jo-2 treated and untreated P815s reflected the extent that perforin and Fas ligand, respectively, were utilized in target cell killing. -- Abnormally high numbers of T cells from HIV-infected individuals undergo spontaneous and activation-induced cell death (AICD), and also are especially sensitive to Fas-mediated apoptosis, suggesting that Fas/Fas ligand (FasL) interactions might contribute to AICD in HIV infection. We used treatment with PMA and ionomycin to investigate the possible role of Fas/FasL interactions in AICD in HIV infection. PMA/ionomycin-induced AICD measured using Cr release, DNA analysis and electron microscopy, demonstrated that PMA and ionomycin acted synergistically to induce up to 70% release of incorporated Cr from fresh PBMC of HIV-infected individuals compared with up to 26% release by healthy volunteers. Cell death required cell-cell contact and extracellular calcium, while it did not involve Fas/FasL interactions or DNA fragmentation, but showed plasma membrane disruption with intact nuclear membranes of damaged cell. We describe a novel form of AICD in T lymphocytes from HIV-infected individuals. -- The presence, number and proportion of activated CD8+ T lymphocytes in the peripheral blood of HIV-infected individuals correlates with disease progression. We examined the associations between autoreactive CTL in the peripheral blood of HIV-infected individuals and disease progression. A significant percentage of HIV-seropositive persons (>50%) in our study cohort, in contrast to healthy individuls showed cytolysis of PHA-activated uninfected lymphocytes. These autoreactive CTL were found to be CD28⁻ CD8⁺ T cells which expanded with disease progression. A high proportion of CD28⁻ CD8⁺ T cells was seen in all HIV-infected individuals with demonstrable levels of circulating CTL. -- We have shown direct association between the autoreactivity and other markers of disease progression such as plasma viral load, CD4⁺ T-cell count, CD8⁺ T cell count, and plasma levels of β₂ microglobulin. The data is in agreement with the proposed hypothesis that these CTL actually contribute to immunodeficiency and clinical progression to AIDS. Based on our data, CTL appear to be a major contributor to disease progression. Further studies based on longitudinal follow-up of these patients may help uncover the functional significance of autoreactive CTL

Persistent CD38 Expression on CD8(+) T Lymphocytes Contributes to Altered Mitochondrial Function and Chronic Inflammation in People With HIV, Despite ART

Background: Age-associated comorbidities are higher in people with HIV (PWH) than HIV-negative individuals. This is partially attributed to immune activation and CD38 expression on T cells driving chronic inflammation. However, the exact contribution of CD38-expressing T cells on the proinflammatory response is not completely understood. Methods: CD38-expressing CD8(+) T lymphocytes were measured from PWH and HIV-negative individuals. Mitochondrial mass, superoxide content, membrane depolarization of CD4(+) and CD8(+) T lymphocytes, and cytokine production after HIV(Gag)-specific peptide stimulation from CD38(+)CD8(+) T lymphocytes of PWH were measured to link biological effects of CD38 expression on cellular metabolism. Results: The frequency of activated CD8(+)CD38(+) T cells persists in PWH on ART compared with HIV-negative individuals. Higher CD38 expression is associated with mitochondrial biogenesis and HIV(Gag)-specific proinflammatory cytokine production in PWH. Blockade of CD38 results in lower Gag-specific cytokine production. Conclusions: ART only partially reduced HIV-induced CD38 expression on CD8(+) T cells. CD8(+) CD38(+) T cells are highly activated in vivo, and HIV-specific stimulation in vitro augments CD38 expression, contributing to a proinflammatory response despite virologic control with ART. Therefore, CD38 is a potential therapeutic target for mitigating chronic inflammation that likely drives cellular aging, comorbidities, and end-organ disease in PWH

Advances in hepatitis B therapeutics

Despite the availability of both effective preventive vaccines and oral antivirals, over 250 million people are chronically infected with the hepatitis B virus (HBV). Globally, chronic hepatitis B is the leading cause of hepatocellular carcinoma, which represents the third cause of cancer mortality, accounting for nearly 1 million annual deaths. Current oral nucleos(t)ide therapy with tenofovir or entecavir suppresses serum HBV-DNA in most treated patients, but rarely is accompanied by HBsAg loss. Thus, treatment has to be given lifelong to prevent viral rebound. A broad spectrum of antivirals that block the HBV life cycle at different steps are in clinical development, including entry inhibitors, cccDNA disrupters/silencers, translation inhibitors, capsid assembly modulators, polymerase inhibitors and secretion inhibitors. Some of them exhibit higher potency than current oral nucleos(t)ides. Drugs in more advanced stages of clinical development are bulevirtide, JNJ-6379, ABI-H0731, ARO-HBV and REP-2139. To date, only treatment with ARO-HBV and with REP-2139 have resulted in HBsAg loss in a significant proportion of patients. Combination therapies using distinct antivirals and/or immune modulators are expected to maximize treatment benefits. The current goal is to achieve a 'functional cure', with sustained serum HBsAg after drug discontinuation. Ultimately, the goal of HBV therapy will be virus eradication, an achievement that would require the elimination of the cccDNA reservoir within infected hepatocytes

Transcriptional profiling of PBMCs unravels B cell mediated immunopathogenic imprints of HCV vasculitis.

B cell depletion therapy using rituximab has been shown to be effective in achieving remission in patients with HCV-mixed cryoglobulinemic (MC) vasculitis. Previously, we have demonstrated abnormalities in peripheral immune cells involving neutrophils, chemotaxis, and innate immune activation among patients with HCV-MC vasculitis when compared to HCV patients without vasculitis. In this study, we evaluated the effect of B cell depletion therapy on transcriptional profiles of peripheral blood mononuclear cells before and after riruximab therapy, in order to unravel the pathogenic mechanism involved in HCV-MC vasculitis induced by abnormal B cell proliferation. DNA microarray analysis was performed using RNA from PBMCs from seven patients with HCV-MC vasculitis and seven normal volunteers. DNA was hybridized to Affymetrix U133A chips. After normalization, differentially expressed gene list with treatment was generated using partitional clustering. RT-PCR, flow cytometry, and enzyme immunoassay (EIA) was used to validate DNA microarray findings. Differentially expressed genes included B cells and non-B cell genes. Validation of genes using purified cell subsets demonstrated distinct effect of B cell depletion therapy on non-B cells, such as monocytes, T cells, and NK cells. Notably, B lymphocyte stimulator (BLyS) levels were persistently elevated in patients who subsequently relapsed. In conclusion, pathogenesis of HCV-MC vasculitis is mediated by abnormal proliferation of B cells, driven by BLyS, leading to significant effects on non-B cells in mediating symptomatology. Future therapeutics using a combination approach of B cell depletion and proliferation may be desired to achieve long-term remission