Persistent Immune Activation Research Articles

Exploring viral reservoir: The combining approach of cell sorting and droplet digital PCR.

Combined antiretroviral therapy (cART) blocks different steps of HIV replication and maintains plasma viral RNA at undetectable levels. The virus can remain in long-living cells and create a reservoir where HIV can restart replicating after cART discontinuation. A persistent viral production triggers and maintains a persistent immune activation, which is a well-known feature of chronic HIV infection, and contributes either to precocious aging, or to the increased incidence of morbidity and mortality of HIV positive patients. The new frontier of the treatment of HIV infection is nowadays eradication of the virus from all host cells and tissues. For this reason, it is crucial to have a clear and precise idea of where the virus hides, and which are the cells that keep it silent. Important efforts have been made to improve the detection of viral reservoirs, and new techniques are now giving the opportunity to characterize viral reservoirs. Among these techniques, a strategic approach based upon cell sorting and droplet digital PCR (ddPCR) is opening new horizons and opportunities of research. This review provides an overview of the methods that combine cell sorting and ddPCR for the quantification of HIV DNA in different cell types, and for the detection of its maintenance.

Tics and Tourette: a clinical, pathophysiological and etiological review.

Describe developments in the etiological understanding of Tourette syndrome. Tourette syndrome is a complex heterogenous clinical syndrome, which is not a unitary entity. Pathophysiological models describe gamma-aminobutyric acid-ergic-associated disinhibition of cortico-basal ganglia motor, sensory and limbic loops. MRI studies support basal ganglia volume loss, with additional white matter and cerebellar changes. Tourette syndrome cause likely involves multiple vulnerability genes and environmental factors. Only recently have some vulnerability gene findings been replicated, including histidine decarboxylase and neurexin 1, yet these rare variants only explain a small proportion of patients. Planned large genetic studies will improve genetic understanding. The role of inflammation as a contributor to disease expression is now supported by large epidemiological studies showing an association with maternal autoimmunity and childhood infection. Investigation of blood cytokines, blood mRNA and brain mRNA expression support the role of a persistent immune activation, and there are similarities with the immune literature of autistic spectrum disorder. Current treatment is symptomatic, although there is a better appreciation of factors that influence treatment response. At present, therapeutics is focused on symptom-based treatments, yet with improved etiological understanding, we will move toward disease-modifying therapies in the future.

IL-23 signaling in Th17 cells is inhibited by HIV infection and is not restored by HAART: Implications for persistent immune activation.

ObjectivesHIV infection causes a profound depletion of gut derived Th17 cells, contributing to loss of mucosal barrier function and an increase in microbial translocation, thus driving systemic immune activation. Despite normalization of circulating CD4+ T cell counts with highly active antiretroviral therapy (HAART), Th17 frequency and function often remain impaired. Given the importance of interleukin (IL)-23 in the generation and stabilization of Th17 cells we hypothesized that impaired IL-23 signaling causes persistent Th17 dysfunction in HIV infection.MethodsThe effects of in vitro HIV infection on responses to IL-23 in Th17 cells were examined. These included the production of IL-17, phosphorylated STAT3 (pSTAT3) and the transcription of retinoic acid orphan receptor C (RORC) gene. Blood derived Th17 cells from untreated and HAART-treated HIV-infected individuals were also examined for the IL-23 induced production of phosphorylated STAT3 (pSTAT3) and the expression of the IL-23 receptors.ResultsIn vitro HIV infection significantly inhibited IL-17 production and IL-23 induced pSTAT3 while expression of RORC RNA was unaffected. Th17 cells isolated from untreated and HAART-treated HIV-infected individuals showed complete loss of IL-23 induced pSTAT3 without a decrease in the expression of the IL-23 receptors.ConclusionsThis study is the first to demonstrate an effect of HIV on the IL-23 signaling pathway in Th17 cells. We show that in vitro and in vivo HIV infection results in impaired IL-23 signaling which is not reversed by HAART nor is it a result of reduced receptor expression, suggesting that HIV interferes with IL-23-activated signaling pathways. These findings may explain the inability of HAART to restore Th17 frequency and function and the resulting persistent chronic immune activation observed in HIV infected individuals.

Reevaluation of immune activation in the era of cART and an aging HIV-infected population.

Biological aging is associated with immune activation (IA) and declining immunity due to systemic inflammation. It is widely accepted that HIV infection causes persistent IA and premature immune senescence despite effective antiretroviral therapy and virologic suppression; however, the effects of combined HIV infection and aging are not well defined. Here, we assessed the relationship between markers of IA and inflammation during biological aging in HIV-infected and -uninfected populations. Antibody response to seasonal influenza vaccination was implemented as a measure of immune competence and relationships between IA, inflammation, and antibody responses were explored using statistical modeling appropriate for integrating high-dimensional data sets. Our results show that markers of IA, such as coexpression of HLA antigen D related (HLA-DR) and CD38 on CD4+ T cells, exhibit strong associations with HIV infection but not with biological age. Certain variables that showed a strong relationship with aging, such as declining naive and CD38+ CD4 and CD8+ T cells, did so regardless of HIV infection. Interestingly, the variable of biological age was not identified in a predictive model as significantly impacting vaccine responses in either group, while distinct IA and inflammatory variables were closely associated with vaccine response in HIV-infected and -uninfected populations. These findings shed light on the most relevant and persistent immune defects during virological suppression with antiretroviral therapy.

Chemokines and Chemokine Receptors: Accomplices for Human Immunodeficiency Virus Infection and Latency.

Chemokines are small chemotactic cytokines that are involved in the regulation of immune cell migration. Multiple functional properties of chemokines, such as pro-inflammation, immune regulation, and promotion of cell growth, angiogenesis, and apoptosis, have been identified in many pathological and physiological contexts. Human immunodeficiency virus (HIV) infection is characterized by persistent inflammation and immune activation during both acute and chronic phases, and the “cytokine storm” is one of the hallmarks of HIV infection. Along with immune activation after HIV infection, an extensive range of chemokines and other cytokines are elevated, thereby generating the so-called “cytokine storm.” In this review, the effects of the upregulated chemokines and chemokine receptors on the processes of HIV infection are discussed. The objective of this review was to focus on the main chemokines and chemokine receptors that have been found to be associated with HIV infection and latency. Elevated chemokines and chemokine receptors have been shown to play important roles in the HIV life cycle, disease progression, and HIV reservoir establishment. Thus, targeting these chemokines and receptors and the other proteins of related signaling pathways might provide novel therapeutic strategies, and the evidence indicates a promising future regarding the development of a functional cure for HIV.

HIV/Human herpesvirus co-infections: Impact on tryptophan-kynurenine pathway and immune reconstitution.

BackgroundCo-infections with human herpesvirus (HHV) have been associated with residual chronic inflammation in antiretroviral (ART)-treated human immunodeficiency virus (HIV)-infected individuals. However, the role of HHV in modulating the tryptophan-kynurenine pathway and clinical outcomes in HIV-infected individuals is poorly understood. Thus, we investigated the seroprevalence of four common HHVs among treated HIV-infected participants and their impact on kynurenine/tryptophan (K/T) ratio and long-term CD4 T-cell recovery in HIV/HHV co-infected participants.MethodIn this cross-sectional study, HIV-infected participants receiving suppressive ART for a minimum of 12 months were recruited from the University Malaya Medical Centre (UMMC), Malaysia. Stored plasma was analyzed for CMV, VZV, HSV-1 and HSV-2 IgG antibody levels, immune activation markers (interleukin-6, interferon-γ, neopterin and sCD14), kynurenine and tryptophan concentrations. The influence of the number of HHV co-infection and K/T ratio on CD4 T-cell recovery was assessed using multivariate Poisson regression.ResultsA total of 232 HIV-infected participants were recruited and all participants were seropositive for at least one HHV; 96.1% with CMV, 86.6% with VZV, 70.7% with HSV-1 and 53.9% with HSV-2. K/T ratio had a significant positive correlation with CMV (rho = 0.205, p = 0.002), VZV (rho = 0.173, p = 0.009) and a tendency with HSV-2 (rho = 0.120, p = 0.070), with CMV antibody titer demonstrating the strongest modulating effect on K/T ratio among the four HHVs assessed in SOM analysis. In multivariate analysis, higher K/T ratio (p = 0.03) and increasing number of HHV co-infections (p<0.001) were independently associated with poorer CD4 T-cell recovery following 12 months of ART initiation.ConclusionMultiple HHV co-infections are common among ART-treated HIV-infected participants in the developing country setting and associated with persistent immune activation and poorer CD4 T-cell recovery.

Novelties in evaluation and monitoring of HIV-1 infection: Is standard virological suppression enough for measuring antiretroviral treatment success?

The high potency and tolerability of the currently available antiretroviral drugs has modified HIV-1 infection from a life-threatening disease to a chronic illness. Nevertheless, some issues still remain open to optimize the management of HIV-1 infected patients in term of maintenance of virological suppression over time, identifying patients that could benefit from simplification therapy, and reducing co-mordibities driven by chronic inflammation. The availability of robust and affordable virological and immunological markers can help in solving these issues by providing information on the burden of HIV-1 reservoir in all the anatomical compartments in which the virus replicates as well as on persistent inflammation, immune activation and senescence despite successful virological suppression. In this light, this review is aimed at providing new insights (arising from a two-day Italian expert meeting hold in Rome in March 2016) in evaluation and monitoring of HIV-1 infection from a virological, immunological and clinical perspective. Particular attention has been focused on role of novel parameters (such as total HIV-1 DNA, residual viremia, and immunological markers) in optimizing treatment strategies, enhancing medical adherence, and individualizing monitoring.

The Canadian HIV and aging cohort study - determinants of increased risk of cardio-vascular diseases in HIV-infected individuals: rationale and study protocol

BackgroundWith potent antiretroviral drugs, HIV infection is becoming a chronic disease. Emergence of comorbidities, particularly cardiovascular disease (CVD) has become a leading concern for patients living with the infection. We hypothesized that the chronic and persistent inflammation and immune activation associated with HIV disease leads to accelerated aging, characterized by CVD. This will translate into higher incidence rates of CVD in HIV infected participants, when compared to HIV negative participants, after adjustment for traditional CVD risk factors. When characterized further using cardiovascular imaging, biomarkers, immunological and genetic profiles, CVD associated with HIV will show different characteristics compared to CVD in HIV-negative individuals.Methods/designThe Canadian HIV and Aging cohort is a prospective, controlled cohort study funded by the Canadian Institutes of Health Research. It will recruit patients living with HIV who are aged 40 years or older or have lived with HIV for 15 years or more. A control population, frequency matched for age, sex, and smoking status, will be recruited from the general population. Patients will attend study visits at baseline, year 1, 2, 5 and 8. At each study visit, data on complete medical and pharmaceutical history will be captured, along with anthropometric measures, a complete physical examination, routine blood tests and electrocardiogram. Consenting participants will also contribute blood samples to a research biobank. The primary outcome is incidence of a composite of: myocardial infarction, coronary revascularization, stroke, hospitalization for angina or congestive heart failure, revascularization or amputation for peripheral artery disease, or cardiovascular death. Preplanned secondary outcomes are all-cause mortality, incidence of the metabolic syndrome, incidence of type 2 diabetes, incidence of renal failure, incidence of abnormal bone mineral density and body fat distribution. Patients participating to the cohort will be eligible to be enrolled in four pre-planned sub-studies of cardiovascular imaging, glucose metabolism, immunological and genetic risk profile.DiscussionThe Canadian HIV and Aging Cohort will provide insights on pathophysiological pathways leading to premature CVD for patients living with HIV.

Abstract P339: Genetically Induced Renal Lymphangiogenesis Prevents the Development of L-NAME Hypertension in Mice

In humans and experimental animals, persistent immune system activation, accumulation of immune cells in the kidney, and subsequent inflammation plays an essential role in the development of hypertension (HTN). To reduce inflammation, lymphatic vessels drain extracellular fluid from the interstitium and traffic immune cells to draining lymph nodes. However, little is known about the connection between hypertension and renal lymphatic vessels. We hypothesized that renal lymphatic vessel density would increase in mice with L-NAME HTN and that genetically induced renal lymphangiogenesis would prevent this increase in blood pressure. L-NAME (0.5 mg/mL) was administered in the drinking water for two weeks and caused HTN (SBP: 153±3 vs. 103±3 mmHg; p&lt;0.05) and renal lymphatic vessel dilation compared to control mice. Kidneys from mice with L-NAME HTN had significantly increased gene expression of the lymphangiogenic marker Vegfc , macrophage marker Adgre1 (F4/80), dendritic cell marker Cd11c , Th1 cell marker Tbx21 , and the pro-inflammatory cytokine Il6 . Blood pressure decreased after a two-week washout period following L-NAME (SBP: 113±2 mmHg) which was associated with a decrease in renal gene expression of Adgre1 (F4/80) and Cd11c , however renal lymphatic vessels remained dilated. To determine if augmenting renal lymphatic vessel density prior to L-NAME treatment would prevent HTN, we used transgenic mice that in response to doxycycline undergo kidney-specific VEGF-D overexpression (KidVD+ mice) and renal lymphangiogenesis. Doxycycline (200 mg/L) was administered in the drinking water of KidVD+ and KidVD- mice for four weeks with L-NAME being added during the final three weeks. Starting doxycycline one week prior to L-NAME prevented HTN in KidVD+ mice while slightly decreasing SBP in KidVD- mice (SBP: 112±4 vs. 134±2 mmHg; p&lt;0.05). Renal gene expression of the Th17 cell marker Rorc was decreased and the lymphatic chemokine markers Ccl21 and Ccl19 were increased significantly in KidVD+ mice. These data together demonstrate that L-NAME HTN can alter the size of renal lymphatic vessels and genetically augmenting renal lymphatic vessel density prior to L-NAME can prevent the development of HTN.

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.

Abstract LB-239: Pharmacodynamic changes confirm the mechanism of action mediating SD-101 efficacy, in combination with pembrolizumab, in a phase 1b/2 study in metastatic melanoma (MEL-01)

Abstract Introduction: SD-101 is a synthetic CpG oligonucleotide agonist of Toll-like receptor 9. SD-101 stimulates dendritic cells to release interferon-alpha and mature into antigen presenting cells that effectively activate T cell responses. Pembrolizumab is a PD-1 inhibitor that has been approved for the treatment of multiple tumors including metastatic melanoma. In mouse tumor models, SD-101 synergizes with anti-PD-1 inducing substantial infiltration of tumor-reactive T cells and durable, complete responses in all treated animals. The MEL-01 trial assesses the safety and preliminary efficacy of SD-101 in combination with pembrolizumab in stage IIIC-IV melanoma. Previously presented clinical data suggest enhanced efficacy for this combination. Biomarker data from the MEL-01 trial support the mechanism of action of SD-101. Methods: The dose escalation phase of this trial is a modified 3 + 3 design with 4 dose levels of SD-101 (1, 2, 4, and 8 mg) in combination with pembrolizumab. SD-101 is injected into a single tumor lesion qw X 4 followed by q3w X 7. Pembrolizumab is dosed at 200 mg IV q3w. Specimens for biomarker analyses included biopsies of the injected tumor and peripheral blood, and were taken before and after treatment (Days 29, 85 and 169). Biopsies were analyzed by multiplexed immunohistochemistry and Nanostring to evaluate the immunophenotype of the tumor environment. Peripheral blood collected immediately before and 24 hours after dosing was analyzed by qPCR with a panel of interferon (IFN) responsive genes to confirm target engagement. Tumor responses were assessed using RECIST v1.1. Results: IFN signature profiling in blood indicated that SD-101 engages its target in a dose-dependent manner. In tumor biopsies taken after the fourth intratumoral injection, an elevated IFN signature was also observed, confirming persistent local immune activation. Nanostring assessments demonstrated increases in multiple immune cell types in tumors in a subset of patients. In particular, an increase in Th1 responses and a decrease in Th2 responses were found, a shift which is consistent the mechanism of action of SD-101. Immunophenotypic signatures generally correlated with tumor response and were greater in patients naïve to PD-1 treatment compared to patients who previously progressed on PD-1 treatment. Signals for immune suppression generally showed an inverse correlation with clinical response. An elevated CD8 profile was detected by Nanostring and confirmed by immunohistochemistry showing increased CD8+ T cell infiltration in tumors. Conclusions: Biomarker assessments of the tumor microenvironment in melanoma patients receiving SD-101 and pembrolizumab demonstrate an immunophenotype with CD8 infiltration and a Th1 driven immune response consistent with the mechanism of action and anti-tumor activity of this combination. Citation Format: Albert Candia, Cristiana Guiducci, Robert L. Coffman, Graeme Currie, Abraham Leung, Robert Janssen, Shivaani Kummar, Sanjiv Agarwala, John Nemunaitis, Rene Gonzalez, Joseph Drabick, Antoni Ribas. Pharmacodynamic changes confirm the mechanism of action mediating SD-101 efficacy, in combination with pembrolizumab, in a phase 1b/2 study in metastatic melanoma (MEL-01) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-239. doi:10.1158/1538-7445.AM2017-LB-239

Soluble Urokinase Plasminogen Activator Receptor Is a Predictor of Incident Non-AIDS Comorbidity and All-Cause Mortality in Human Immunodeficiency Virus Type 1 Infection.

Persistent inflammation and immune activation have been associated with non-AIDS comorbidity and mortality in human immunodeficiency virus (HIV) infection. We aimed to investigate the potential association between soluble urokinase plasminogen activator receptor (suPAR) and incident non-AIDS comorbidity and all-cause mortality in a well-treated HIV-infected population. suPAR was measured by enzyme-linked immunosorbent assay, and events of comorbidity and mortality were ascertained by registry linkage. The study showed an independent association between a high suPAR level at baseline and increased hazard rates for both non-AIDS comorbidities (cardiovascular disease, chronic kidney disease, chronic lung disease, liver disease, and cancer) and all-cause mortality.

Macrophages and Phospholipases at the Intersection between Inflammation and the Pathogenesis of HIV-1 Infection.

Persistent low grade immune activation and chronic inflammation are nowadays considered main driving forces of the progressive immunologic failure in effective antiretroviral therapy treated HIV-1 infected individuals. Among the factors contributing to this phenomenon, microbial translocation has emerged as a key driver of persistent immune activation. Indeed, the rapid depletion of gastrointestinal CD4+ T lymphocytes occurring during the early phases of infection leads to a deterioration of the gut epithelium followed by the translocation of microbial products into the systemic circulation and the subsequent activation of innate immunity. In this context, monocytes/macrophages are increasingly recognized as an important source of inflammation, linked to HIV-1 disease progression and to non-AIDS complications, such as cardiovascular disease and neurocognitive decline, which are currently main challenges in treated patients. Lipid signaling plays a central role in modulating monocyte/macrophage activation, immune functions and inflammatory responses. Phospholipase-mediated phospholipid hydrolysis leads to the production of lipid mediators or second messengers that affect signal transduction, thus regulating a variety of physiologic and pathophysiologic processes. In this review, we discuss the contribution of phospholipases to monocyte/macrophage activation in the context of HIV-1 infection, focusing on their involvement in virus-associated chronic inflammation and co-morbidities.

Kidney transplant outcomes in HIV serodiscordant recipient pairs

Kidney transplant outcomes in HIV serodiscordant recipient pairs

Pre-ART Immune Abnormalities Persist After ART Initiation

The mechanism of persistent immune activation despite long-term suppressive antiretroviral therapy (ART) for HIV infection remains unclear. To better

Vitamin D deficiency is associated with IL-6 levels and monocyte activation in HIV-infected persons

BackgroundImmune activation plays a key role in HIV pathogenesis. Markers of inflammation have been associated with vitamin D deficiency in the general population. Studies have also demonstrated associations of vitamin D deficiency with increased risk of HIV progression and death. The relationship between persistent inflammation and immune activation during chronic HIV infection and vitamin D deficiency remains unclear.MethodsCryopreserved specimens were analyzed from 663 participants at the time of enrollment from the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (SUN Study) from 2004 to 2006. Biomarkers of inflammation, atherosclerosis, and coagulation were measured using enzyme-linked immunosorbent assays (ELISAs) and electrochemiluminescence. 25(OH)D, the stable precursor form of vitamin D, was measured using a radioimmunoassay with levels defined as: normal (≥30ng/mL), insufficient (20–29 ng/mL) and deficient (<20 ng/mL). Monocyte phenotypes were assessed by flow cytometry. Linear and logistic regression models were used to determine statistical associations between biomarkers and vitamin D deficiency.Results25(OH)D levels were deficient in 251 (38%) participants, insufficient in 222 (34%), and normal in 190 (29%). Patients with vitamin D deficiency, when compared to those with insufficient or normal vitamin D levels, had increased levels of IL-6 (23%; p<0.01), TNF-α (21%, p = 0.03), D-dimer (24%, p = 0.01), higher proportions of CD14dimCD16+ (22%, p<0.01) and CX3CR1+ monocytes (48%; p<0.001) and decreased frequency of CCR2+ monocytes (-3.4%, p<0.001). In fully adjusted models, vitamin D associations with abnormal biomarker levels persisted for IL-6 levels and CX3CR1+ and CCR2+ phenotypes.ConclusionsVitamin D deficiency is associated with greater inflammation and activated monocyte phenotypes. The role of vitamin D deficiency in persistent immune activation and associated complications during chronic HIV disease should be further evaluated as a possible target for intervention.

MicroRNA miR-126-5p Enhances the Inflammatory Responses of Monocytes to Lipopolysaccharide Stimulation by Suppressing Cylindromatosis in Chronic HIV-1 Infection.

Persistent immune activation during chronic human immunodeficiency virus type 1 (HIV-1) infection facilitates immune dysfunction and thereby fuels disease progression. The translocation of bacterial derivatives into blood and the hyperinflammatory responsiveness of monocytes have been considered important causative factors for persistent immune activation. Whether microRNAs (miRNAs) are involved in regulating monocyte-mediated inflammatory responses during chronic HIV-1 infection remains elusive. In this study, we show that miR-126-5p functions as a positive regulator of monocyte-mediated inflammatory responses. Significantly increased miRNA miR-126-5p and decreased cylindromatosis (CYLD) were observed in primary monocytes from chronic HIV-1 patients. Inhibition of miR-126-5p in monocytes from chronic HIV-1 patients attenuated the responsiveness of these cells to lipopolysaccharide (LPS) stimulation. Gain-of-function assays confirmed that miR-126-5p could downregulate CYLD, which in turn caused an upregulation of phosphorylation of JNK protein (pJNK) and enhanced inflammatory responses of monocytes to LPS stimulation. Overall, miR-126-5p upregulates the responsiveness of monocytes to LPS stimulation in chronic HIV-1 infection, and the suppression of miR-126-5p and the promotion of CYLD expression in primary monocytes may represent a practical immune intervention strategy to contain persistent inflammation in chronic HIV-1 infection.IMPORTANCE Monocyte-mediated hyperinflammatory responses during chronic HIV-1 infection are important causative factors driving AIDS progression; however, the underlying mechanism has not been fully addressed. We demonstrated that miR-126-5p, one of the most upregulated miRNAs during chronic HIV-1 infection, could enhance the inflammatory responses of monocytes to LPS by suppressing the inhibitory protein CYLD and thereby unleashing the expression of pJNK in the LPS/Toll-like receptor 4/mitogen-activated protein kinase pathway. This observation reveals a new mechanism for HIV-1 pathogenesis, which could be targeted by immune intervention.

Effects of pitavastatin and pravastatin on markers of immune activation and arterial inflammation in HIV.

Persistent immune activation is thought to contribute to increased cardiovascular disease risk in HIV and statins may help modulate systemic immune activation. We aimed to compare the effects of two key statins on markers of systemic immune activation and arterial inflammation in the HIV population. Double-blind, active-controlled, parallel-group comparative trial performed in 45 sites. Two hundred and fifty-two antiretroviral therapy-treated HIV-infected participants with dyslipidemia were randomized (1 : 1) to pitavastatin 4 mg daily vs. pravastatin 40 mg daily in the HIV-infected patieNts and TREatment with PItavastatin vs. pravastatin for Dyslipidemia (INTREPID) trial. In this analysis of the INTREPID trial, we assessed markers of immune activation and arterial inflammation using a modified intent-to-treat population. This trial is registered with ClinicalTrials.gov (NCT01301066). One hundred and twenty-six participants were randomized to receive pitavastatin and 126 to pravastatin. Ninety-nine participants in the pitavastatin group and 91 participants in the pravastatin group completed the study. Median age was 50 (45, 56) years [median (interquartile range)]. Baseline, low-density lipoprotein-cholestrol (LDL-C) was 153 (135, 171) mg/dl, log HIV-1 viral load was 1.1 ± 0.2 copies/ml, and CD4 cell count was 580 (439, 794) cells/μl. At week 52, the pitavastatin group had a significantly greater reduction (% change) compared with pravastatin in soluble CD14 (sCD14), (-10.0 vs. 0.6%, P = 0.02), oxidized LDL (oxLDL) (-26.9 vs. -17.5%, P = 0.02), and lipoprotein-associated phospholipase 2 (Lp-PLA2) (-26.6 vs. -15.5%, P = 0.005) (pitavastatin vs. pravastatin). Fifty-two weeks of pitavastatin 4 mg daily (vs. pravastatin 40 mg daily) led to a greater reduction in select markers of immune activation and arterial inflammation (sCD14, oxLDL, and LpPLA2) among HIV-infected participants. Further work is needed to assess whether immune-modulatory effects of pitavastatin reduce cardiovascular disease risk in HIV.

Human Immunodeficiency Virus Type-1 Myeloid Derived Suppressor Cells Inhibit Cytomegalovirus Inflammation through Interleukin-27 and B7-H4

HIV/CMV co-infected persons despite prolonged viral suppression often experience persistent immune activation, have an increased frequency of myeloid derived suppressor cells (MDSC) and are at increased risk for cardiovascular disease. We examined how HIV MDSC control CD4+ T cell IFNγ response to a CMVpp65 peptide pool (CMVpp65). We show that HIV/CMV co-infected persons with virologic suppression and recovered CD4+ T cells compared to HIV(−)/CMV(+) controls exhibit an increase in CD4+CX3CR1+IFNγ+ cells in response to CMVpp65; MDSC depletion further augmented CD4+CX3CR1+IFNγ+ cells and IFNγ production. IL-2 and IFNγ in response to CMVpp65 were enhanced with depletion of MDSC expanded in presence of HIV (HIV MDSC), but decreased with culture of HIV MDSC with autologous PBMCs. CMVpp65 specific CD4+CX3CR1+IFNγ+ cells were also decreased in presence of HIV MDSC. HIV MDSC overexpressed B7-H4 and silencing B7-H4 increased the production of IL-2 and IFNγ from autologous cells; a process mediated through increased phosphorylated (p)-Akt upon stimulation with CMVpp65. Additionally, IL-27 regulated the expression of B7-H4 on HIV MDSC, and controlled CMV-specific T cell activity by limiting CMVpp65-IFNγ production and expanding CD4+IL-10+ regulatory T cells. These findings provide new therapeutic targets to control the chronic immune activation and endothelial cell inflammation observed in HIV-infected persons.

Causal Pathways from Enteropathogens to Environmental Enteropathy: Findings from the MAL-ED Birth Cohort Study

BackgroundEnvironmental enteropathy (EE), the adverse impact of frequent and numerous enteric infections on the gut resulting in a state of persistent immune activation and altered permeability, has been proposed as a key determinant of growth failure in children in low- and middle-income populations. A theory-driven systems model to critically evaluate pathways through which enteropathogens, gut permeability, and intestinal and systemic inflammation affect child growth was conducted within the framework of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) birth cohort study that included children from eight countries. MethodsNon-diarrheal stool samples (N=22,846) from 1253 children from multiple sites were evaluated for a panel of 40 enteropathogens and fecal concentrations of myeloperoxidase, alpha-1-antitrypsin, and neopterin. Among these same children, urinary lactulose:mannitol (L:M) (N=6363) and plasma alpha-1-acid glycoprotein (AGP) (N=2797) were also measured. The temporal sampling design was used to create a directed acyclic graph of proposed mechanistic pathways between enteropathogen detection in non-diarrheal stools, biomarkers of intestinal permeability and inflammation, systemic inflammation and change in length- and weight- for age in children 0–2years of age. FindingsChildren in these populations had frequent enteric infections and high levels of both intestinal and systemic inflammation. Higher burdens of enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, were associated with elevated biomarker concentrations of gut and systemic inflammation and, via these associations, indirectly associated with both reduced linear and ponderal growth. Evidence for the association with reduced linear growth was stronger for systemic inflammation than for gut inflammation; the opposite was true of reduced ponderal growth. Although Giardia was associated with reduced growth, the association was not mediated by any of the biomarkers evaluated. InterpretationThe large quantity of empirical evidence contributing to this analysis supports the conceptual model of EE. The effects of EE on growth faltering in young children were small, but multiple mechanistic pathways underlying the attribution of growth failure to asymptomatic enteric infections had statistical support in the analysis. The strongest evidence for EE was the association between enteropathogens and linear growth mediated through systemic inflammation. FundingBill & Melinda Gates Foundation.