T-cell Immune Activation Research Articles

Humanized mouse models to study pathophysiology and treatment of HIV infection.

Immunodeficient mice that lack all lymphocyte subsets and have phagocytic cells that are tolerant of human cells can be stably xenografted with human hematopoietic stem cell as well as other human tissues (fetal liver and thymus) creating 'human immune system' (HIS) mice. HIS mice develop all major human lymphocyte classes (B, T, natural killer, and innate lymphoid cell) and their specialized subsets as well as a variety of myeloid cells (dendritic cell, monocytes, and macrophages) thereby providing a small animal model in which to interrogate human immune responses to infection. HIS mouse models have been successfully used to study several aspects of HIV-1 biology, including viral life cycle (entry, restriction, replication, and spread) as well as virus-induced immunopathology (CD4 T-cell depletion, immune activation, and mucosal inflammation). Recent work has shown that HIV reservoirs can be established in HIV-infected HIS mice after treatment with combinations of antiretroviral drugs thereby providing a model to test new approaches to eliminate latently infected cells. HIS mice provide cost-effective preclinical platform to assess combination immunotherapies that can target HIV reservoirs. Therapeutic strategies validated in HIS mice should be considered in designing the roadmap toward HIV 'cure'.

Plasma Tryptophan-Kynurenine Metabolites Are Altered in Human Immunodeficiency Virus Infection and Associated With Progression of Carotid Artery Atherosclerosis.

It is unknown whether disrupted tryptophan catabolism is associated with cardiovascular disease (CVD) in human immunodeficiency virus (HIV)-infected individuals. Plasma tryptophan and kynurenic acid were measured in 737 women and men (520 HIV+, 217 HIV-) from the Women's Interagency HIV Study and the Multicenter AIDS Cohort Study. Repeated B-mode carotid artery ultrasound imaging was obtained from 2004 through 2013. We examined associations of baseline tryptophan, kynurenic acid, and kynurenic acid-to-tryptophan (KYNA/TRP) ratio, with risk of carotid plaque. After a 7-year follow-up, 112 participants developed carotid plaque. Compared to those without HIV infection, HIV-infected participants had lower tryptophan (P < .001), higher KYNA/TRP (P = .01), and similar kynurenic acid levels (P = .51). Tryptophan, kynurenic acid, and KYNA/TRP were correlated with T-cell activation (CD38+HLA-DR+) and immune activation markers (serum sCD14, galectin-3) but had few correlations with interleukin-6, C-reactive protein, or CVD risk factors (blood pressure, lipids). Adjusted for demographic and behavioral factors, each standard deviation (SD) increment in tryptophan was associated with a 29% (95% confidence interval [CI], 17%-38%) decreased risk of carotid plaque (P < .001), while each SD increment in kynurenic acid (P = .02) and KYNA/TRP (P < .001) was associated with a 34% (6%-69%) and a 47% (26%-73%) increased risk of carotid plaque, respectively. After further adjustment for CVD risk factors and immune activation markers, these associations were attenuated but remained significant. Plasma tryptophan-kynurenine metabolites are altered in HIV infection and associated with progression of carotid artery atherosclerosis.

Regulatory T Cells Contribute to HIV-1 Reservoir Persistence in CD4+ T Cells Through Cyclic Adenosine Monophosphate-Dependent Mechanisms in Humanized Mice In Vivo.

Regulatory T cells (Tregs) suppress T-cell immune activation and human immunodeficiency virus type 1 (HIV-1) replication, but the role of Tregs in HIV-1 reservoir persistence is poorly defined. Tregs were depleted by denileukin diftitox in humanized mice with chronic HIV-1 infection. Viral replication in lineage cells was determined by p24 expression. Levels of HIV-1 RNA and DNA in human cells, as well as replication-competent-virus-producing cells, were measured to quantified viral replication and reservoirs. Treg depletion resulted in a blip of HIV-1 replication in T cells but not in myeloid cells. The major activated reservoir cells were memory CD4+ T cells in vivo. Interestingly, the transient activation of viral replication led to HIV-1 reservoir reduction after viremia resuppression, as indicated by the quantity of HIV-1 DNA and replication-competent-virus-producing cells. Furthermore, we demonstrated that Tregs use cyclic adenosine monophosphate (cAMP)-dependent protein kinase A pathway to inhibit HIV-1 activation and replication in resting conventional T cells in vitro. Tregs suppress HIV-1 replication in T cells and contribute to HIV-1 reservoir persistence. cAMP produced in Tregs is involved in their suppression of viral gene activation and expression. Treg depletion combined with combination antiretroviral therapy provides a novel strategy for HIV-1 cure.

Elevated humoral response to cytomegalovirus in HIV-infected individuals with poor CD4+ T-cell immune recovery.

Some HIV-infected c-ART-suppressed individuals show incomplete CD4+ T-cell recovery, abnormal T-cell activation and higher mortality. One potential source of immune activation could be coinfection with cytomegalovirus (CMV). IgG and IgM levels, immune activation, inflammation and T-cell death in c-ART-suppressed individuals with CD4+ T-cell counts >350 cells/μL (immunoconcordant, n = 133) or <350 cells/μL (immunodiscordant, n = 95) were analyzed to evaluate the effect of CMV humoral response on immune recovery. In total, 27 HIV-uninfected individuals were included as controls. In addition, the presence of CMV IgM antibodies was retrospectively analyzed in 58 immunoconcordant individuals and 66 immunodiscordant individuals. Increased CMV IgG levels were observed in individuals with poor immune reconstitution (p = 0.0002). Increased CMV IgG responses were significantly correlated with lower nadir and absolute CD4+ T-cell counts. In contrast, CMV IgG responses were positively correlated with activation (HLA-DR+) and death markers in CD4+ T-cells and activated memory CD8+ T-cells (CD45RA-CD38+). Longitudinal subanalysis revealed an increased frequency of IgM+ samples in individuals with poor CD4+ T-cell recovery, and an association was observed between retrospective IgM positivity and the current level of IgG. The magnitude of the humoral immune response to CMV is associated with nadir CD4+ T-cell counts, inflammation, immune activation and CD4+ T-cell death, thus suggesting that CMV infection may be a relevant driving force in the increased morbidity/mortality observed in HIV+ individuals with poor CD4+ T-cell recovery.

Protocol of a randomised controlled trial characterising the immune responses induced by varicella-zoster virus (VZV) vaccination in healthy Kenyan women: setting the stage for a potential VZV-based HIV vaccine

IntroductionA protective HIV vaccine would be expected to induce durable effector immune responses at the mucosa, restricting HIV infection at its portal of entry. We hypothesise that use of varicella-zoster...

Cytomegalovirus viraemia is associated with poor growth and T-cell activation with an increased burden in HIV-exposed uninfected infants.

Objective:Factors associated with poor health in HIV-exposed-uninfected (HEU) infants are poorly defined. We describe the prevalence and correlates of cytomegalovirus (CMV) viraemia in HEU and HIV-unexposed-uninfected (HUU) infants, and quantify associations with anthropometric, haematological, and immunological outcomes.Design:Cross-sectional, including HEU and HUU infants from rural coastal Kenya.Methods:Infants aged 2–8 months were studied. The primary outcome was CMV viraemia and viral load, determined by quantitative PCR. Correlates were tested by logistic and linear regression; coefficients were used to describe associations between CMV viraemia and clinical/immunological parameters.Results:In total, 42 of 65 (64.6%) infants had CMV viraemia [median viral load, 3.0 (interquartile ranges: 2.7–3.5) log10 IU/ml]. Compared to community controls, HEU infants had six-fold increased odds of being viraemic (adjusted odds ratio 5.95 [95% confidence interval: 1.82–19.36], P = 0.003). Age, but not HEU/HUU status, was a strong correlate of CMV viral load (coefficient = −0.15, P = 0.009). CMV viral load associated negatively with weight-for-age (WAZ) Z-score (coefficient = −1.06, P = 0.008) and head circumference-for-age Z-score (coefficient = −1.47, P = 0.012) and positively with CD8+ T-cell coexpression of CD38/human leucocyte antigen DR (coefficient = 15.05, P = 0.003).Conclusion:The odds of having CMV viraemia was six-fold greater in HEU than HUU infants when adjusted for age. CMV viral load was associated with adverse growth and heightened CD8+ T-cell immune activation. Longitudinal assessments of the clinical effects of primary CMV infection and associated immunomodulation in early life in HEU and HUU populations are warranted.

Impact of intensified antiretroviral therapy during early HIV infection on gut immunology and inflammatory blood biomarkers

Standard antiretroviral therapy (ART) is slow to reverse gut mucosal immune defects that cause persistent inflammation and immune activation. We examined whether intensifying early-administered ART through the addition of maraviroc and raltegravir would accelerate their resolution. ART-naïve men with early HIV infection were randomized in a double-blind manner to receive ART (emtricitabine/tenofovir disoproxil fumarate + lopinavir/ritonavir), together with either combined placebo or raltegravir + maraviroc, for 48 weeks. In a predefined substudy, paired blood and sigmoid biopsies were collected at baseline and week 48. Mucosal CD4 T-cell immune subsets (Th1, Th17, and Th22 cells), CD8 T-cell immune activation, and soluble blood markers of inflammation (IL-6, IL-17, macrophage inflammatory protein-1b, soluble CD14, and IL-10) and coagulation (D-dimer) were measured. A total of 22 participants were enrolled, a median of 4 months after HIV acquisition. At baseline, there was substantial systemic and mucosal immune activation, and gut CD4 T-cell numbers, Th22 cell numbers, and Th17 cell function were reduced compared with controls. Early ART restored gut Th22 numbers, improved but did not restore overall CD4 numbers, and had no impact on Th17 function. Plasma levels of soluble CD14 and D-dimer normalized, whereas other inflammatory cytokines were reduced but not normalized. ART intensification had no impact on any blood or gut immune parameters. Early HIV infection causes substantial mucosal and systemic immune activation, and gut CD4 T-cell dysfunction. One year of ART improved but did not normalize most parameters, regardless of intensification with raltegravir and maraviroc, and did not restore mucosal Th17 function.

Low Bone Mineral Density in Vertically HIV-infected Children and Adolescents: Risk Factors and the Role of T-cell Activation and Senescence.

Our aim was to determine the prevalence and risk factors associated with low bone mineral density (BMD) in vertically HIV-infected patients and to investigate whether low BMD is related to immune activation and senescence induced by HIV infection. A cross-sectional study was performed in 98 vertically HIV-infected patients. BMD was measured by dual-energy radiograph absorptiometry at lumbar spine. Height adjustment of BMD Z score was performed using height-for-age Z score. T-cell immune activation and senescence were analyzed in a subgroup of 54 patients by flow cytometry. Median age was 15.9 years, 71.4% were Caucasian, 99% received antiretroviral therapy and 80.6% had undetectable viral load. Low BMD (BMD Z score ≤ -2) was present in 15.3% of cases, but after height adjustment in 4.1% of cases. Height-adjusted BMD Z score was positively correlated with body mass index Z score, CD4/CD8 ratio and nadir CD4, and inversely with duration of severe immunosuppression and parathyroid hormone values. In the multivariate model including age, gender, ethnicity, encephalopathy, Tanner stage, nadir CD4, duration of viral suppression, CD4 count, CD4/CD8 ratio, body mass index, cumulative duration of antiretroviral therapy, tenofovir and protease inhibitors exposure, nadir CD4 was independently associated to height-adjusted BMD Z score. No association was found between height-adjusted BMD Z score and T-cell activation or senescence. The prevalence of low BMD in vertically HIV-infected patients was low after height adjustment. Nadir CD4, but not T-cell activation or senescence, was an independent predictor for low BMD. Larger and prospective studies are needed to achieve better knowledge of the pathogenesis of low BMD in vertical HIV infection.

Integrative Analysis of Immunological Data to Explore Chronic Immune T-Cell Activation in Successfully Treated HIV Patients.

ObjectivesTo unravel the complex relationships between cytomegalovirus-induced-, autoimmune-induced responses, microbial translocation and chronic immune activation (CIA) in successfully treated HIV-infected patients and to explore the mediating role of alpha-interferon in these processes.DesignCross-sectional study nested in the ANRS CO3 Aquitaine Cohort, a prospective hospital-based cohort of HIV-1-infected patients in South-Western France.MethodsPatients initiated antiretroviral therapy between 2005 and 2008 and were treated with sustained virological suppression for at least two years. CIA was defined by the percentage of HLA-DR+/CD38+ among CD8+T-cells. Integrative analyses were performed using structural equation modelling (SEM).ResultsThe main analysis was performed in 57 HLA-A*0201 positive patients, due to availability of percentages of actin-, vimentin-, lamin-specific CD8+T-cells (HLA-A2-restricted tests) to further characterize autoimmune response. Cytomegalovirus-induced response was assessed by Quantiferon and pp-65 ELISPOT. SEM revealed a direct effect of cytomegalovirus-induced response on CIA (standardized estimate βstd = 0.56, p-value = 0.0004). The effect of autoimmune-induced response on CIA was indirect through alpha-interferon pathway, assessed by expression levels of 5 alpha-interferon-stimulated genes ADAR, ISG15, IFIT1, Mx1 and OAS1 (effect of autoimmune response on alpha-interferon: βstd = 0.36, p-value = 0.0401; effect of alpha-interferon on CIA: βstd = 0.39, p-value = 0.0044). There was no direct effect of autoimmune-induced response on CIA (p-value = 0.3169). Microbial translocation as measured by 16SrDNA and sCD14 in plasma was not associated with CIA. Results were consistent in 142 patients in whom cytomegalovirus and auto-immunity responses were measured by Quantiferon and anti-nuclear antibodies, respectively. All analyses performed in HLA-A*0201 positive patients and in the overall population revealed a significant effect of IFN-α latent variable on CIA.ConclusionThe role of cytomegalovirus-induced response on CIA was confirmed as well as the involvement of alpha-interferon on CIA. The indirect effect of auto-immunity response on CIA revealed through the alpha-interferon pathway requires further investigation to confirm the potential role of auto-immunity for CIA in HIV-infected patients.

MicroRNA-155 is a biomarker of T-cell activation and immune dysfunction in HIV-1-infected patients.

MicroRNA-155 (miR-155) regulates T-cell differentiation and activation. It has also been associated with HIV infection. However, it remains unclear whether miR-155 is related to the T-cell response in HIV-infected individuals (e.g. T-cell activation and exhaustion). We performed a cross-sectional study involving 121 HIV-1-infected patients on highly active antiretroviral therapy (HAART) and 43 HAART-naïve patients. MiR-155 levels in the peripheral blood were determined by quantitative reverse transcription-polymerase chain reaction (PCR). T-cell immune activation, exhaustion, and homeostasis were measured by determining the expression of CD38, programmed death 1 (PD-1) and CD127 via flow cytometry. The levels of miR-155 in total peripheral blood mononuclear cells, CD4 T cells and CD8 T cells from HIV-1-infected patients were increased (P < 0.01). Nonresponders and HAART-naïve patients also exhibited a higher percentage of CD8+ CD38+ T cells and a lower percentage of CD4+ CD127+ and CD8+ CD127+ T cells (P < 0.05). We also found higher levels of PD-1 expression on the CD4+ and CD8+ T cells of HIV-1-infected patients (P < 0.05). Our findings suggest that miR-155 levels in the peripheral blood of HIV-1-infected patients are increased and associated with T-cell activation. Therefore, miR-155 is a potential biomarker of the immune response following HIV-1 infection.

Increased Immune Activation and Exhaustion in HIV-infected Youth.

Immune activation and exhaustion drive several comorbidities and disease progression in HIV-infected adults; however, they are not well studied in HIV-infected youth. Thus, this study sought to examine levels of immune activation and exhaustion in this population, investigate associated HIV- and non-HIV-related variables and compare results with a matched healthy control group. HIV-infected youth 8-25 years of age on stable antiretroviral therapy with an HIV-1 RNA level <1000 copies/mL were enrolled, along with matched healthy controls. We measured T-cell and monocyte immune activation and exhaustion markers in cryopreserved peripheral blood mononuclear cell and plasma samples. A total of 136 subjects (80 HIV+: 66% male; 91% black) were enrolled. Markers of CD4+ and CD8+ T-cell activation were higher in the HIV-infected group versus controls [mean % CD4+CD38+HLA-DR+ and CD8+CD38+HLA-DR+ = 2.2 versus 1.5 (P=0.002) and 4.9 versus 2.2 (P<0.0001), respectively], as were exhausted CD4+ and CD8+ T-cells [mean % CD4+CD38+HLA-DR+PD-1+ and CD8+CD38+HLA-DR+PD-1+ = 1.0 versus 0.5 (P<0.0001) and 1.6 versus 0.7 (P<0.0001), respectively]. There were no differences in proportions of inflammatory or patrolling monocytes between groups (P>0.05); however, soluble CD14 was higher in HIV-infected compared with controls (1.6 versus 1.4 µg/mL; P=0.01). Current CD4 count, low-density lipoprotein cholesterol and age were the variables most associated with CD4+ and CD8+ T-cell activation. CD4+ and CD8+ T-cell immune activation and exhaustion are higher in HIV-infected youth compared with matched controls, while monocyte subpopulations are not altered despite a high soluble CD14 level. The clinical significance of the increased immune activation and exhaustion should be further explored.

Immune tolerance properties of the testicular tissue as a viral sanctuary site in ART-treated HIV-infected adults.

HIV persistence in long-lived infected cells and in anatomical sanctuary sites are major hurdles to HIV eradication. Testicular tissue may represent a significant viral sanctuary site as it constitutes an immunologically privileged compartment. We assessed immunotolerance properties of the testicular tissue in individuals receiving suppressive antiretroviral therapy (ART). Testicular tissue and matched blood samples were collected from six virally suppressed adults and 10 HIV-uninfected controls prior to sex reassignment surgery. T cells were purified from freshly isolated testicular interstitial cell suspensions. T-cell subsets, expression of immune activation markers and HIV DNA were assessed in matched testicular cells and peripheral blood mononuclear cells (PBMCs). When compared with PBMCs, testes were characterized by a lower CD4 T-cell proportion among total T cells, a decrease in the frequency of naive cells, an increase in the frequency of effector-memory T cells and an increase in CCR5 expression in both the HIV+ and HIV- groups. In HIV-infected individuals on ART, testes displayed higher T-cell immune activation (Coexpression of CD38 and Human Leukocyte Antigen - antigen D Related) than PBMCs. In both groups, testes were characterized by higher frequencies of immunosuppressive CD39 regulatory T cells and a massive increase in CD73 expression on CD8 T cells. In addition, a remarkable increase in indoleamine-pyrrole 2,3-dioxygenase immunosuppressive enzyme involved in tryptophan/kynurenine catabolism was observed in testes versus blood. Rare cells harboring HIV DNA were detected in testes from five out six participants. These findings suggest that the adenosine and tryptophan/kynurenine immune-metabolic pathways contribute to immune tolerance in testicular tissue. Our results suggest that testes may represent a distinctive HIV sanctuary site during ART.

Baseline Naive CD4+ T-cell Level Predicting Immune Reconstitution in Treated HIV-infected Late Presenters.

Background:Among HIV-infected patients initiating antiretroviral therapy (ART), early changes in CD4+ T-cell subsets are well described. However, HIV-infected late presenters initiating treatment present with a suboptimal CD4+ T-cell reconstitution and remain at a higher risk for AIDS and non-AIDS events. Therefore, factors associated with CD4+ T-cell reconstitution need to be determined in this population, which will allow designing effective immunotherapeutic strategies.Methods:Thirty-one adult patients with baseline CD4+ T-cell count <350 cells/mm3 exhibiting viral suppression after ART initiation were followed in the HIV/AIDS research center of Peking Union Medical College Hospital in Beijing, China, from October 2002 to September 2013. Changes in T-cell subsets and associated determinants were measured.Results:Median baseline CD4+ T-cell count was 70 cells/mm3. We found a biphasic reconstitution of T-cell subsets and immune activation: a rapid change during the first 6 months followed by a more gradual change over the subsequent 8 years. Baseline CD4+ T-cell count >200 cells/mm3 in comparison to CD4+ T-cell count ≤200 cells/mm3 was associated with more complete immune Reconstitution (77.8% vs. 27.3% respectively; P = 0.017) and normalized CD4/CD8 ratio. We showed that the baseline percentage of naive CD4+ T-cell was a predictive marker for complete immune reconstitution (area under receiver operating characteristic curve 0.907), and 12.4% as cutoff value had a sensitivity of 84.6% and a specificity of 88.2%.Conclusions:Baseline naive CD4+ T-cell percentage may serve as a predictive marker for optimal immune reconstitution during long-term therapy. Such study findings suggest that increasing thymic output should represent an avenue to improve patients who are diagnosed late in the course of infection.

Enhanced stimulation of anti-breast cancer T cells responses by dendritic cells loaded with poly lactic-co-glycolic acid (PLGA) nanoparticle encapsulated tumor antigens.

BackgroundDeveloping safe and effective cancer vaccine formulations is a primary focus in the field of cancer immunotherapy. Dendritic cells (DC) are currently employed as cellular vaccine in clinical trials of tumor immunotherapy. Recognizing the critical role of DCs in initiating anti-tumor immunity has resulted in the development of several strategies that target vaccine antigens to DCs to trigger anti-tumor T cell responses. To increase the efficiency of antigen delivery systems for anti-tumor vaccines, encapsulation of tumor-associated antigens in polymer nanoparticles (NPs) has been established.MethodsIn this study, the effect of tumor lysate antigen obtained from three stage III breast cancer tissues encapsulated within PLGA NPs to enhance the DC maturation was investigated. The T-cell immune response activation was then fallowed up. Fresh breast tumors were initially used to generate tumor lysate antigens containing poly lactic-co-glycolic acid (PLGA) NP. The encapsulation efficiency and release kinetics were profiled. The efficiency of encapsulation was measured using Bradford protein assays measuring the dissolved NPs. The stability of released antigen from NPs was verified using SDS-PAGE. To evaluate the hypothesis that NPs enhances antigen presentation, including soluble tumor lysate, tumor lysate containing NPs and control NPs the efficiency of NP-mediated tumor lysate delivery to DCs was evaluated by assessing CD3+ T-cell stimulation after T cell/and DCs co-culture.ResultsThe rate of encapsulation was increased by enhancing the antigen concentration of tumor lysate. However, increasing the antigen concentration diminished the encapsulation efficiency. In addition, higher initial protein contenting NPs led to a greater cumulative release. All three patients released variable amounts of IFN-γ, IL-10, IL-12 and IL-4 in response to re-stimulation. T cells stimulated with lysate-pulsed DCs induced a substantial increase in IFN-γ and IL-12 production. We demonstrated that NPs containing tumor lysate can induce maturation and activation of DCs, as antigen alone does.ConclusionPLGA-NPs are attractive vehicles for protein antigen delivery which effectively induce stimulation and maturation of DCs, allowing not only an enhanced antigen processing and immunogenicity or improved antigen stability, but also the targeted delivery and slow release of antigens.

Can Probiotics Reduce Inflammation and Enhance Gut Immune Health in People Living with HIV: Study Designs for the Probiotic Visbiome for Inflammation and Translocation (PROOV IT) Pilot Trials

Objectives: Despite substantial improvements in HIV outcomes with combination antiretroviral therapy (cART), morbidity and mortality remain above population norms. The gut mucosal immune system is not completely restored by cART, and the resultant microbial translocation may contribute to chronic inflammation, inadequate CD4 T-cell recovery, and increased rates of serious non-AIDS events. Since the microbial environment surrounding a CD4 T cell may influence its development and function, we hypothesize that probiotics provided during cART might reduce inflammation and improve gut immune health in HIV-positive treatment-naïve individuals (PROOV IT I) and individuals with suboptimal CD4 recovery on cART (PROOV IT II).Methods: These prospective, double-blinded, randomized, placebo-controlled, multicenter pilot studies will assess the impact of the probiotic Visbiome at 900 billion bacteria daily. Forty HIV positive cART-naïve men will be randomized in the PROOV IT I study, coincident with antiretroviral initiation, and be followed for 24 weeks. In PROOV IT II, 36 men on cART, but with a CD4 T-cell count below 350 cells/mm3 will be followed for 48 weeks. The primary outcome for both studies is the comparison of blood CD8 T-cell immune activation. Secondary analyses will include comparison of blood inflammatory biomarkers, microbial translocation, blood and gut immunology and HIV levels, the bacterial community composition, diet, intestinal permeability, and the safety, adherence and tolerability of the study product.Discussion: These studies will evaluate the ability of probiotics as a safe and tolerable therapeutic intervention to reduce systemic immune activation and to accelerate gut immune restoration in people living with HIV.

The plasma levels of soluble ST2 as a marker of gut mucosal damage in early HIV infection.

Objective:Following tissue barrier breaches, interleukin-33 (IL-33) is released as an ‘alarmin’ to induce inflammation. Soluble suppression of tumorigenicity 2 (sST2), as an IL-33 decoy receptor, contributes to limit inflammation. We assessed the relationship between the IL-33/ST2 axis and markers of gut mucosal damage in patients with early (EHI) and chronic HIV infection (CHI) and elite controllers.Design:Analyses on patients with EHI and CHI were conducted to determine IL-33/sST2 changes over time.Methods:IL-33 and sST2 levels were measured in plasma. Correlations between sST2 levels and plasma viral load, CD4+ and CD8+ T-cell counts, expression of T-cell activation/exhaustion markers, gut mucosal damage, microbial translocation and inflammation markers, as well as kynurenine/tryptophan ratio were assessed.Results:Plasma sST2 levels were elevated in EHI compared with untreated CHI and uninfected controls, whereas IL-33 levels were comparable in all groups. In EHI, sST2 levels were positively correlated with the CD8+ T-cell count and the percentage of T cells expressing activation and exhaustion markers, but not with viral load or CD4+ T-cell count. Plasma sST2 levels also correlated with plasma levels of gut mucosal damage, microbial translocation and kynurenine/tryptophan ratio and for some markers of inflammation. Prospective analyses showed that early antiretroviral therapy had no impact on sST2 levels, whereas longer treatment duration initiated during CHI normalized sST2.Conclusion:As sST2 levels were elevated in EHI and were correlated with CD8+ T-cell count, immune activation, and microbial translocation, sST2 may serve as a marker of disease progression, gut damage and may directly contribute to HIV pathogenesis.

MiR-424(322) reverses chemoresistance via T-cell immune response activation by blocking the PD-L1 immune checkpoint.

Immune checkpoint blockade of the inhibitory immune receptors PD-L1, PD-1 and CTLA-4 has emerged as a successful treatment strategy for several advanced cancers. Here we demonstrate that miR-424(322) regulates the PD-L1/PD-1 and CD80/CTLA-4 pathways in chemoresistant ovarian cancer. miR-424(322) is inversely correlated with PD-L1, PD-1, CD80 and CTLA-4 expression. High levels of miR-424(322) in the tumours are positively correlated with the progression-free survival of ovarian cancer patients. Mechanistic investigations demonstrated that miR-424(322) inhibited PD-L1 and CD80 expression through direct binding to the 3′-untranslated region. Restoration of miR-424(322) expression reverses chemoresistance, which is accompanied by blockage of the PD-L1 immune checkpoint. The synergistic effect of chemotherapy and immunotherapy is associated with the proliferation of functional cytotoxic CD8+ T cells and the inhibition of myeloid-derived suppressive cells and regulatory T cells. Collectively, our data suggest a biological and functional interaction between PD-L1 and chemoresistance through the microRNA regulatory cascade.

Increase in frequencies of circulating Th-17 cells correlates with microbial translocation, immune activation and exhaustion in HIV-1 infected patients with poor CD4 T-cell reconstitution

We analyzed the association of circulating Th-17 cells (cTh-17) with immune activation (IA), immune exhaustion (IE) and regulatory T-cells (T-regs) in 20 human immunodeficiency virus-1 (HIV-1) infected patients with impaired restoration of CD4 T-cell counts despite prolonged suppression of plasma viremia (discordant) and compared it with 20 HIV-1 infected patients showing good immunologic and virologic responses (concordant) following highly active antiretroviral therapy (HAART). Discordant HIV-1 infected patients showed significantly higher frequencies of cTh-17 cells compared to concordant patients and healthy controls after PMA+Ionomicin stimulation. Discordant patients also showed higher CD4 T-cell immune activation (HLA-DR+CD38+) than concordant patients which directly correlated with microbial translocation. Additionally, CD4 T-cells of discordant patients showed higher frequencies of CD4 T-cells expressing multiple immune exhaustion markers (Tim3+PD-1+) which correlated with immune activation indicating that combined analysis of inhibitory molecules along with PD-1 might be a better predictor for immune exhaustion of CD4 T-cells. Increased cTh-17 cell frequency correlated inversely with CD4 T-cell percentages and absolute counts and directly with CD4 T-cell immune activation and T-reg frequencies. Persistent CD4 T-cell immune activation might favor differentiation of activated CD4 T-cells toward cTh-17 phenotype in discordant patients. Discordant patients had significantly lower baseline CD4 T-cell counts and higher viral load at the initiation of HAART and higher immune activation and immune exhaustion after being on HAART for long time indicating that these factors might be associated with an increase in cTh-17 cell frequency, thus, increasing the risk of disease progression despite virologic control.

Atorvastatin restricts HIV replication in CD4+ T cells by upregulation of p21

Antigen persistence due to HIV is a major source of inflammation and substantial immune activation, both of which are linked to accelerated aging. This illustrates the need to reduce immune activation in these patients and subsequently decrease the risk of cardiovascular diseases and other non-AIDS-defining comorbidities. CD4 T cells were infected with HIV-1 isolates in the presence or absence of atorvastatin (0.25 to 1 μg/ml) for 24-48 h. Atorvastatin-induced anti-inflammatory functions and anti-viral replication were measured in vitro. Atorvastatin, a lipid-lowering medication, exerted a broad spectrum of anti-inflammatory functions by reducing T-cell immune activation markers (e.g. CD38, HLA-DR and Ki67), lowering HIV-1 co-receptor CCR-5, and decreasing proliferative capabilities of CD4 T cells in vitro. In contrast, atorvastatin expanded regulatory T cells (Tregs) and upregulated the expression of T-cell immunoglobulin and ITIM domain (TIGIT), which enhanced the suppressive activity of Tregs. Furthermore, atorvastatin upregulated the cyclin-dependent kinase inhibitor p21, which is also known as cip-1 and waf-1, in the CD4 T cells. Upregulation of p21 in CD4 T cells rendered them less susceptible to HIV-1 infection and replication whereas siRNA-mediated p21 depletion and/or p21 selective inhibitor rescued viral replication. Interestingly, atorvastatin reduced HIV infection in both rested and phytohemagglutinin-activated CD4 T cells in vitro. Finally, atorvastatin mediated p21 upregulation occurred via mevalonate pathway, but independent of p53. The results demonstrate a novel mechanism by which atorvastatin induced resistance of CD4 T cells to HIV-1 infection via p21 upregulation and suggest that statins may hold particular promise for some HIV-infected individuals.

Robust Reconstitution of Tuberculosis-Specific Polyfunctional CD4+ T-Cell Responses and Rising Systemic Interleukin 6 in Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome.

The immunopathogenesis of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) remains unclear. We determined the association between pathogen-specific T-cell responses and development of paradoxical TB-IRIS on antiretroviral therapy (ART). This study was nested within a prospective cohort study of HIV-infected patients with active pulmonary tuberculosis and baseline CD4 counts ≤125 cells/µL initiating ART. T-cell immune activation (CD38, HLA-DR, and PD-1 expression), phenotype, and polyfunctional pathogen-specific cellular immune responses prior to and 4 weeks after ART initiation were determined by flow cytometry. Patients with TB-IRIS were compared to non-IRIS controls using χ(2) and rank-sum tests and logistic regression. TB-IRIS patients and controls had similar CD4 counts, levels of T-cell-associated immune activation, frequencies of T-cell memory subsets, and frequencies of interferon gamma (IFN-γ(+))/interleukin 2 (IL-2(+))/tumor necrosis factor alpha (TNF-α(+)) CD4(+) T-cells prior to ART initiation. After ART initiation, cellular immune activation and T-cell subsets also were similar in TB-IRIS patients and controls. In contrast, TB-IRIS patients had significantly greater early increases in the frequency of tuberculosis-specific polyfunctional IFN-γ(+)/IL-2(+)/TNF-α(+) CD4(+) T-cells on ART (P = .02); each quartile increase in the percentage of these cells was independently associated with a 2.8-fold increased risk of TB-IRIS (95% confidence interval, 1.1 to 7.5-fold). In a secondary analysis, patients with TB-IRIS had rapid, concomitant increases in tuberculosis-specific adaptive immune responses and interleukin 6 (IL-6) levels, whereas controls with similarly rapid increases in cellular immune function had IL-6 levels that tended to decrease on ART. Rapid expansion of tuberculosis-specific polyfunctional CD4(+) T-cell responses, likely linked to increases in IL-6, is associated with development of paradoxical TB-IRIS.