The Th17/Treg ratio, IL-1RA and sCD14 levels in primary HIV infection predict the T-cell activation set point in the absence of systemic microbial translocation

The Gut and the Translocated Microbiomes in HIV Infection: Current Concepts and Future Avenues

It is widely acknowledged that HIV infection results in disruption of the gut's mucosal integrity partly due a profound loss of gastrointestinal CD4+ T cells that are targets of the virus. In addition, systemic inflammation and immune activation that drive disease pathogenesis are reduced but not normalized by antiretroviral therapy (ART). It has long been postulated that through the process of microbial translocation, the gut microbiome acts as a key driver of systemic inflammation and immune recovery in HIV infection. As such, many studies have aimed at characterizing the gut microbiota in order to unravel its influence in people with HIV and have reported an association between various bacterial taxa and inflammation. This review assesses both contra-dictory and consistent findings among several studies in order to clarify the overall mechanisms by which the gut microbiota in adults may influence immune recovery in HIV infection. Independently of the gut microbiome, observations made from analysis of microbial products in the blood provide direct insight into how the translocated microbiome may drive immune recovery. To help better understand strengths and limitations of the findings reported, this review also highlights the numerous factors that can influence microbiome studies, be they experimental methodologies, and host-intrinsic or host-extrinsic factors. Altogether, a fuller understanding of the interplay between the gut microbiome and immunity in HIV infection may contribute to preventive and therapeutic approaches.

Virion-incorporated CD14 enables HIV-1 to bind LPS and initiate TLR4 signaling in immune cells

HIV-1 has a broad range of nuanced interactions with the immune system, and the incorporation of cellular proteins by nascent virions continues to redefine our understanding of the virus-host relationship. Proteins located at the sites of viral egress can be selectively incorporated into the HIV-1 envelope, imparting new functions and phenotypes onto virions, and impacting viral spread and disease. Using virion capture assays and western blot, we show that HIV-1 can incorporate the myeloid antigen CD14 into its viral envelope. Virion-incorporated CD14 remained biologically active and able to bind its natural ligand, bacterial lipopolysaccharide (LPS), as demonstrated by flow virometry and immunoprecipitation assays. Using a Toll-like receptor 4 (TLR4) reporter cell line, we also demonstrated that virions with bound LPS can trigger TLR4 signaling to activate transcription factors that regulate inflammatory gene expression. Complementary assays with THP-1 monocytes demonstrated enhanced secretion of inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and the C-C chemokine ligand 5 (CCL5), when exposed to LPS-loaded virus. These data highlight a new type of interplay between HIV-1 and the myeloid cell compartment, a previously well-established cellular contributor to HIV-1 pathogenesis and inflammation. Persistent gut inflammation is a hallmark of chronic HIV-1 infection, and contributing to this effect is the translocation of microbes across the gut epithelium. Our data herein provide proof of principle that virion-incorporated CD14 could be a novel mechanism through which HIV-1 can drive chronic inflammation, facilitated by HIV-1 particles binding bacterial LPS and initiating inflammatory signaling in TLR4-expressing cells.IMPORTANCEHIV-1 establishes a lifelong infection accompanied by numerous immunological changes. Inflammation of the gut epithelia, exacerbated by the loss of mucosal T cells and cytokine dysregulation, persists during HIV-1 infection. Feeding back into this loop of inflammation is the translocation of intestinal microbes across the gut epithelia, resulting in the systemic dissemination of bacterial antigens, like lipopolysaccharide (LPS). Our group previously demonstrated that the LPS receptor, CD14, can be readily incorporated by HIV-1 particles, supporting previous clinical observations of viruses derived from patient plasma. We now show that CD14 can be incorporated by several primary HIV-1 isolates and that this virion-incorporated CD14 can remain functional, enabling HIV-1 to bind to LPS. This subsequently allowed CD14+ virions to transfer LPS to monocytic cells, eliciting pro-inflammatory signaling and cytokine secretion. We posit here that virion-incorporated CD14 is a potential contributor to the dysregulated immune responses present in the setting of HIV-1 infection.

Primary HIV infection features colonic damage and neutrophil inflammation yet containment of microbial translocation

INTRODUCTION

Impairment of the gastrointestinal barrier leads to microbial translocation and peripheral immune activation, which are linked to disease progression. Data in the setting of primary HIV/SIV infection suggest that gut barrier damage is one of the first events of the pathogenic cascade, preceding mucosal immune dysfunction and microbial translocation. We assessed gut structure and immunity as well as microbial translocation in acutely and chronically-infected, combination antiretroviral therapy (cART)-naive individuals.

METHODS

Fifteen people with primary HIV infection (P-HIV) and 13 with chronic HIV infection (C-HIV) c-ART-naive participants were cross-sectionally studied. Gut biopsies were analysed in terms of gut reservoirs (total, integrated and unintegrated HIV DNA); tight junction proteins (E-cadherin, Zonula Occludens-1), CD4 + expression, neutrophil myeloperoxidase (histochemical staining); collagen deposition (Masson staining). Flow cytometry was used to assess γδ T-cell frequency (CD3 + panγδ+Vδ1+/Vδ2+). In plasma, we measured microbial translocation (LPS, sCD14, EndoCAb) and gut barrier function (I-FABP) markers (ELISA).

RESULTS

P-HIV displayed significantly higher tissue HIV DNA, yet neutrophil infiltration and collagen deposition in the gut were similar in the two groups. In contrast, microbial translocation markers were significantly lower in P-HIV compared with C-HIV. A trend to higher mucosal E-cadherin, and gut γδ T-cells was also observed in P-HIV.

CONCLUSION

Early HIV infection features higher HIV DNA in the gut, yet comparable mucosal alterations to those observed in chronic infection. In contrast, microbial translocation is contained in primary HIV infection, likely because of a partial preservation of E-cadherin and mucosal immune subsets, namely γδ T-cells.

Alterations in Th17 Cells and Non-Classical Monocytes as a Signature of Subclinical Coronary Artery Atherosclerosis during ART-Treated HIV-1 Infection

Cardiovascular disease (CVD) remains an important comorbidity in people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Our previous studies performed in the Canadian HIV/Aging Cohort Study (CHACS) (>40 years-old; Framingham Risk Score (FRS) > 5%) revealed a 2-3-fold increase in non-calcified coronary artery atherosclerosis (CAA) plaque burden, measured by computed tomography angiography scan (CTAScan) as the total (TPV) and low attenuated plaque volume (LAPV), in ART-treated PLWH (HIV+) versus uninfected controls (HIV-). In an effort to identify novel correlates of subclinical CAA, markers of intestinal damage (sCD14, LBP, FABP2); cell trafficking/inflammation (CCL20, CX3CL1, MIF, CCL25); subsets of Th17-polarized and regulatory (Tregs) CD4+ T-cells, classical/intermediate/non-classical monocytes, and myeloid/plasmacytoid dendritic cells were studied in relationship with HIV and TPV/LAPV status. The TPV detection/values coincided with higher plasma sCD14, FABP2, CCL20, MIF, CX3CL1, and triglyceride levels; lower Th17/Treg ratios; and classical monocyte expansion. Among HIV+, TPV+ versus TPV- exhibited lower Th17 frequencies, reduced Th17/Treg ratios, higher frequencies of non-classical CCR9lowHLADRhigh monocytes, and increased plasma fibrinogen levels. Finally, Th17/Treg ratios and non-classical CCR9lowHLADRhigh monocyte frequencies remained associated with TPV/LAPV after adjusting for FRS and HIV/ART duration in a logistic regression model. These findings point to Th17 paucity and non-classical monocyte abundance as novel immunological correlates of subclinical CAA that may fuel the CVD risk in ART-treated PLWH.

A Blood Immunological Signature of Subclinical Coronary Artery Atherosclerosis in People Living with HIV-1 Receiving Antiretroviral Therapy

Cardiovascular disease (CVD) remains an important co-morbidity in people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Our previous studies performed on the Canadian HIV/Aging Cohort Study (CHACS) (>40 years-old; Framingham Risk Score (FRS) >5%), revealed a 2-3-fold increase in non-calcified coronary artery atherosclerosis (CAA) plaque burden, measured by Computed tomography angiography scan (CTAScan) as total (TPV) and low attenuated plaque volume (LAPV) in ART-treated PLWH (HIV+) versus uninfected controls (HIV-). In an effort to identify novel correlates of subclinical CAA, markers of intestinal damage (sCD14, LBP, FABP2); cell trafficking/inflammation (CCL20, CX3CL1, MIF, CCL25); subsets of Th17-polarized and regulatory (Tregs) CD4 + T-cells, classical/intermediate/non-classical monocytes, and myeloid/plasmacytoid dendritic cells, were studied in relationship with HIV and TPV/LAPV status. The TPV detection/values coincided with higher plasma sCD14, FABP2, CCL20, MIF, CX3CL1 and triglyceride levels, lower Th17/Treg ratios, and classical monocyte expansion. Among HIV + , TPV + versus TPV - exhibited lower Th17 frequencies, reduced Th17/Treg ratios, higher frequencies of non-classical CCR9 low HLADR high monocyte, and increased plasma fibrinogen levels. Finally, Th17/Treg ratios and non-classical CCR9 low HLADR high monocyte frequencies remained associated with TPV/LAPV after adjusting for FRS and HIV/ART duration in a logistic regression model. These findings point to Th17 paucity and non-classical monocyte abundance as novel immunological correlates of subclinical CAA that may fuel the CVD risk in ART-treated PLWH.

HIV-1-Host Interaction in Gut-Associated Lymphoid Tissue (GALT): Effects on Local Environment and Comorbidities

HIV-1 replication in the gastrointestinal (GI) tract causes severe CD4+ T-cell depletion and disruption of the protective epithelial barrier in the intestinal mucosa, causing microbial translocation, the main driver of inflammation and immune activation, even in people living with HIV (PLWH) taking antiretroviral drug therapy. The higher levels of HIV DNA in the gut compared to the blood highlight the importance of the gut as a viral reservoir. CD4+ T-cell subsets in the gut differ in phenotypic characteristics and differentiation status from the ones in other tissues or in peripheral blood, and little is still known about the mechanisms by which the persistence of HIV is maintained at this anatomical site. This review aims to describe the interaction with key subsets of CD4+ T cells in the intestinal mucosa targeted by HIV-1 and the role of gut microbiome and its metabolites in HIV-associated systemic inflammation and immune activation that are crucial in the pathogenesis of HIV infection and related comorbidities.

Immuno-metabolic control of the balance between Th17-polarized and regulatory T-cells during HIV infection

Th17-polarized CD4⁺ effector T-cells together with their immunosuppressive regulatory T-cell (Treg) counterparts, with transcriptional profiles governed by the lineage transcription factors RORγt/RORC2 and FOXP3, respectively, are important gatekeepers at mucosal interfaces. Alterations in the Th17/Treg ratios, due to the rapid depletion of Th17 cells and increased Treg frequencies, are a hallmark of both HIV and SIV infections and a marker of disease progression. The shift in Th17/Treg balance, in favor of increased Treg frequencies, contributes to gut mucosal permeability, immune dysfunction, and microbial translocation, subsequently leading to chronic immune activation/inflammation and disease progression. Of particular interest, Th17 cells and Tregs share developmental routes, with changes in the Th17 versus Treg fate decision influencing the pro-inflammatory versus anti-inflammatory responses. The differentiation and function of Th17 cells and Tregs rely on independent yet complementary metabolic pathways. Several pathways have been described in the literature to be involved in Th17 versus Treg polarization, including 1) the activity of ectonucleotidases CD39/CD73; 2) the increase in TGF-β1 production; 3) a hypoxic environment, and subsequent upregulation in hypoxia-inducible factor-1α (HIF-1α); 4) the increased mTOR activity and glycolysis induction; 5) the lipid metabolism, including fatty acid synthesis, fatty acids oxidation, cholesterol synthesis, and lipid storage, which are regulated by the AMPK, mevalonate and PPARγ pathways; and 6) the tryptophan catabolism. These metabolic pathways are understudied in the context of HIV-1 infection. The purpose of this review is to summarize the current knowledge on metabolic pathways that are dysregulated during HIV-1 infection and their impact on Th17/Treg balance.

Natural Killer Cells Regulate Acute SIV Replication, Dissemination, and Inflammation, but Do Not Impact Independent Transmission Events

Natural killer (NK) cells are potent effector cells of the innate immune system possessing both cytotoxic and immunoregulatory capabilities, which contribute to their crucial role in controlling human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections. However, despite significant evidence for NK cell modulation of HIV disease, their specific contribution to transmission and control of acute infection remains less clear. To elucidate the contribution of NK cells during acute SIV infection, we performed an acute necropsy study, where rhesus macaques (RM) were subjected to preinfection depletion of systemic NK cells using established methods of IL-15 neutralization, followed by subsequent challenge with barcoded SIVmac239X. Our study showed that depletion was highly effective, resulting in near total ablation of all NK cell subsets in blood, liver, oral, and rectal mucosae, and lymph nodes (LN) that persisted through the duration of the study. Meanwhile, frequencies and phenotypes of T cells remained virtually unchanged, indicating that our method of NK cell depletion had minimal off-target effects. Importantly, NK cell-depleted RM demonstrated an early and sustained 1 to 2 log increase in viremia over controls, but sequence analysis suggested no difference in the number of independent transmission events. Acute bulk, central memory (CM), and CCR5⁺ CD4⁺ T cell depletion was similar between experimental and control groups, while CD8⁺ T cell activation was higher in NK cell-depleted RM as measured by Ki67 and PD-1 expression. Using 27-plex Luminex analyses, we also found modestly increased inflammatory cytokines in NK cell-depleted RM compared to control animals. In the effort to determine the impact of NK cells on HIV/SIV transmission and acute viremia, future studies will be necessary to better harness these cells for future viral therapies. Collectively, these data suggest NK cells are important modulators of lentivirus dissemination and disease but may not have the capacity to independently eliminate individual transmission events. IMPORTANCE Natural killer (NK) cells as major effector cells of the innate immune system can contribute significantly to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) control. However, a specific role for NK cells in blocking lentivirus transmission remains incompletely clear. In this study, we depleted NK cells prior to challenge with a barcoded SIV. Importantly, our studied showed systemic NK cell depletion was associated with a significant increase in acute viremia, but did not impact the number of independent transmission events. Collectively, these data suggest NK cells are critical modulators of early lentivirus replication but may not regulate individual transmission events at mucosal portals of entry.

Alterations in circulating markers in HIV/AIDS patients with poor immune reconstitution: Novel insights from microbial translocation and innate immunity

After long-term anti-retroviral therapy (ART) treatment, most human immunodeficiency virus (HIV)/Acquired Immure Deficiency Syndrome (AIDS) patients can achieve virological suppression and gradual recovery of CD4⁺ T-lymphocyte (CD4⁺ T cell) counts. However, some patients still fail to attain normal CD4⁺ T cell counts; this group of patients are called immune non-responders (INRs), and these patients show severe immune dysfunction. The potential mechanism of poor immune reconstitution (PIR) remains unclear and the identification of uniform biomarkers to predict the occurrence of PIR is particularly vital. But limited information is available on the relationship between circulating markers of INRs and immune recovery. Hence, this review summarises alterations in the intestine microbiota and associated markers in the setting of PIR to better understand host-microbiota-metabolite interactions in HIV immune reconstitution and to identify biomarkers that can predict recovery of CD4⁺ T cell counts in INRs.

Evaluation of cytokine levels in response to mitogen among HIV-1-infected blood cells and their relationships to the number of T cells

BACKGROUND

Human immunodeficiency virus-1 (HIV-1) infection causes loss and anergy of CD4⁺ and CD8⁺ T cells, leading to opportunistic infections, including tuberculosis (TB). QuantiFERON®-TB (QFT) is used as a diagnostic tool to detect TB, but it exhibits limited accuracy among subjects with low CD4⁺ T cell numbers, including HIV-1-infected individuals. The present study aimed to determine the effect of HIV-1 infection and patients' blood T cell numbers on cytokine production in response to mitogen (Mit) stimulation.

METHODS

The number of CD4⁺ and CD8⁺ T cells in HIV-1-infected individuals was quantified. Levels of various cytokines in Mit-stimulated and un-stimulated (Nil) supernatants of QFT gold "in tube" were assessed using a MAGPIX System. The correlation between cytokine levels and CD4⁺/CD8⁺ T cell counts in response to Mit was analyzed. The cytokine levels were compared between HIV-1-infected and healthy subjects.

RESULTS

HIV-1-infected individuals (110) and control subjects (27) were enrolled. Interferon (IFN)-γ, interleukin-1 receptor antagonist (IL-1RA), IL-6, IL-8, and regulated on activation, normal T cell expressed and secreted (RANTES) values in Mit-Nil tubes showed a significant correlation with CD4⁺ T cell counts, while IFN-γ, IL-6, and IFN-γ-induced protein 10 (IP-10) values in Mit-Nil tubes had significant correlation with CD8⁺ T cell counts. IL-1RA, IL-8, IP-10, platelet-derived growth factor (PDGF)-BB, and RANTES levels in Nil tubes were significantly higher in the HIV-1-infected group. IFN-γ, IL-2, IL-5, IL-6, IP-10, and macrophage inflammatory protein-1β values in Mit-Nil tubes were significantly higher, and PDGF-BB and RANTES levels were significantly lower in the HIV-1-infected group.

CONCLUSION

The functions of HIV-1-infected T cells and uninfected T cells, such as spontaneous and responsive cytokine production in response to Mit, were different. Our findings may be useful for developing new clinical tools for patients with low T cell counts. Additionally, the study provides new insights into the pathogenesis of HIV-1 infection.

So Pathogenic or So What?-A Brief Overview of SIV Pathogenesis with an Emphasis on Cure Research

HIV infection requires lifelong antiretroviral therapy (ART) to control disease progression. Although ART has greatly extended the life expectancy of persons living with HIV (PWH), PWH nonetheless suffer from an increase in AIDS-related and non-AIDS related comorbidities resulting from HIV pathogenesis. Thus, an HIV cure is imperative to improve the quality of life of PWH. In this review, we discuss the origins of various SIV strains utilized in cure and comorbidity research as well as their respective animal species used. We briefly detail the life cycle of HIV and describe the pathogenesis of HIV/SIV and the integral role of chronic immune activation and inflammation on disease progression and comorbidities, with comparisons between pathogenic infections and nonpathogenic infections that occur in natural hosts of SIVs. We further discuss the various HIV cure strategies being explored with an emphasis on immunological therapies and "shock and kill".

Plasma sVCAM-1, antiretroviral therapy and mortality in HIV-1-infected West African adults

OBJECTIVES

We report the association between pre-antiretroviral therapy (pre-ART) soluble vascular cell adhesion molecule-1 (sVCAM-1) levels and long-term mortality in HIV-infected West African adults participating in a trial of early ART in West Africa (Temprano ANRS 12136 trial).

METHODS

The ART-naïve HIV-infected adults were randomly assigned to start ART immediately or defer ART until the WHO criteria were met. Participants who completed the trial follow-up were invited to participate in a post-trial phase (PTP). The PTP end-point was all-cause death. We used multivariable Cox proportional models to analyse the association between baseline sVCAM-1 and all-cause death, adjusting for ART strategy, sex, CD4 count, plasma HIV-1 RNA and peripheral blood mononuclear cell HIV-1 DNA levels.

RESULTS

In all, 954 adults (77% women, median CD4 count of 387 cells/μL) were randomly assigned to start ART immediately (n = 477) or to defer initiation of ART (n = 477). They were followed for a median of 5.8 years [interquartile range (IQR): 5.2-6.3]. In multivariable analysis, the risk of death was significantly associated with baseline sVCAM-1 [≥1458 vs. < 1458 ng/mL; adjusted hazard ratio = 2.86, 95% confidence interval (CI): 1.60-5.11]. The 6-year probability of death rates were 14.4% (95%CI: 9.1-22.6) and 9.4% (5.4-16.1) in patients with baseline sVCAM-1 ≥ 1458 ng/mL randomized to deferred and immediate ART, respectively, and 3.8% (2.2-6.5) and 3.5% (1.9-6.3) in patients with baseline sVCAM-1 < 1458 ng/mL randomized to deferred and immediate ART. The median difference between pre-ART and 12-month sVCAM-1 levels in patients randomized to immediate ART was -252 (IQR: -587 to -61).

CONCLUSIONS

Pre-ART sVCAM-1 levels were significantly associated with mortality, independently of whether ART was started immediately or deferred, but they significantly decreased after 12 months of ART.

Increased Platelet-CD4+ T Cell Aggregates Are Correlated With HIV-1 Permissiveness and CD4+ T Cell Loss

Chronic HIV-1 infection is associated with persistent inflammation, which contributes to disease progression. Platelet-T cell aggregates play a critical role in maintaining inflammation. However, the phenotypic characteristics and clinical significance of platelet-CD4+ T cell aggregates remain unclear in different HIV-infected populations. In this study, we quantified and characterized platelet-CD4+ T cell aggregates in the peripheral blood of treatment-naïve HIV-1-infected individuals (TNs), immunological responders to antiretroviral therapy (IRs), immunological non-responders to antiretroviral therapy (INRs), and healthy controls (HCs). Flow cytometry analysis and immunofluorescence microscopy showed increased platelet-CD4+ T cell aggregate formation in TNs compared to HCs during HIV-1 infection. However, the frequencies of platelet-CD4+ T cell aggregates decreased in IRs compared to TNs, but not in INRs, which have shown severe immunological dysfunction. Platelet-CD4+ T cell aggregate frequencies were positively correlated with HIV-1 viral load but negatively correlated with CD4+ T cell counts and CD4/CD8 ratios. Furthermore, we observed a higher expression of CD45RO, HIV co-receptors, HIV activation/exhaustion markers in platelet-CD4+ T cell aggregates, which was associated with HIV-1 permissiveness. High levels of caspase-1 and caspase-3, and low levels of Bcl-2 in platelet-CD4+ T cell aggregates imply the potential role in CD4+ T cell loss during HIV-1 infection. Furthermore, platelet-CD4+ T cell aggregates contained more HIV-1 gag viral protein and HIV-1 DNA than their platelet-free CD4+ T cell counterparts. The platelet-CD4+ T cell aggregate levels were positively correlated with plasma sCD163 and sCD14 levels. Our findings demonstrate that platelet-CD4+ T cell aggregate formation has typical characteristics of HIV-1 permissiveness and is related to immune activation during HIV-1 infection.

Overt IL-32 isoform expression at intestinal level during HIV-1 infection is negatively regulated by IL-17A

OBJECTIVES

Untreated HIV infection was previously associated with IL-32 overexpression in gut/intestinal epithelial cells (IEC). Here, we explored IL-32 isoform expression in the colon of people with HIV (PWH) receiving antiretroviral therapy (ART) and IL-32 triggers/modulators in IEC.

DESIGN

Sigmoid colon biopsies (SCB) and blood were collected from ART-treated PWH (HIV + ART; n = 17; mean age: 56 years; CD4+ cell counts: 679 cells/μl; time on ART: 72 months) and age-matched HIV-uninfected controls (HIVneg; n = 5). The IEC line HT-29 was used for mechanistic studies.

METHODS

Cells from SCB and blood were isolated by enzymatic digestion and/or gradient centrifugation. HT-29 cells were exposed to TLR1-9 agonists, TNF-α, IL-17A and HIV. IL-32α/β/γ/D/ε/θ and IL-17A mRNA levels were quantified by real-time RT-PCR. IL-32 protein levels were quantified by ELISA.

RESULTS

IL-32β/γ/ε isoform transcripts were detectable in the blood and SCB, with IL-32β mRNA levels being predominantly expressed in both compartments and at significantly higher levels in HIV + ART compared to HIVneg. IL-17A transcripts were only detectable in SCB, with increased IL-17A levels in HIVneg compared with HIV + ART and negatively correlated with IL-32β mRNA levels. IL-32β/γ/ε isoform mRNA were detected in HT-29 cells upon exposure to TNF-α, Poly I:C (TLR3 agonist), Flagellin (TLR-5 agonist) and HIV. IL-17A significantly decreased both IL-32 β/γ/ε mRNA and cell-associated IL-32 protein levels induced upon TNF-α and Poly I:C triggering.

CONCLUSION

We document IL-32 isoforms abundant in the colon of ART-treated PWH and reveal the capacity of the Th17 hallmark cytokine IL-17A to attenuate IL-32 overexpression in a model of inflamed IEC.

Oral immune dysfunction is associated with the expansion of FOXP3+PD-1+Amphiregulin+ T cells during HIV infection

Residual systemic inflammation and mucosal immune dysfunction persist in people living with HIV, despite treatment with combined anti-retroviral therapy, but the underlying immune mechanisms are poorly understood. Here we report that the altered immune landscape of the oral mucosa of HIV-positive patients on therapy involves increased TLR and inflammasome signaling, localized CD4+ T cell hyperactivation, and, counterintuitively, enrichment of FOXP3+ T cells. HIV infection of oral tonsil cultures in vitro causes an increase in FOXP3+ T cells expressing PD-1, IFN-γ, Amphiregulin and IL-10. These cells persist even in the presence of anti-retroviral drugs, and further expand when stimulated by TLR2 ligands and IL-1β. Mechanistically, IL-1β upregulates PD-1 expression via AKT signaling, and PD-1 stabilizes FOXP3 and Amphiregulin through a mechanism involving asparaginyl endopeptidase, resulting in FOXP3+ cells that are incapable of suppressing CD4+ T cells in vitro. The FOXP3+ T cells that are abundant in HIV-positive patients are phenotypically similar to the in vitro cultured, HIV-responsive FOXP3+ T cells, and their presence strongly correlates with CD4+ T cell hyper-activation. This suggests that FOXP3+ T cell dysregulation might play a role in the mucosal immune dysfunction of HIV patients on therapy.

Formulation of a recombinant HIV-1 polytope candidate vaccine with naloxone/alum mixture: induction of multi-cytokine responses with a higher regulatory mechanism

The potency of a vaccine highly depends upon the nature of the adjuvant used. There are a variety of ineffective vaccines, such as HIV-1 vaccine candidates, that need to be optimized with new adjuvant formulations to improve vaccine potency and efficacy. Studies show the potency of naloxone (NLX)/alum mixture in the induction of Th1/Th2 response for vaccine. However, other immunologic patterns inducing by this adjuvant and its immunoregulatory effect is unclear. In this regard, the aim of the present study was to investigate the effect of the NLX/alum mixture, as an adjuvant, on cytokine networks and immunoregulatory activity for an HIV-1 polytope vaccine. BALB/c mice were divided into six groups (n = 6) and immunized subcutaneously with 10 μg of the vaccine formulated with NLX/alum, NLX, alum, and Freund's adjuvants. At the same time, the mice in the control groups received an equal volume of PBS or NLX. The lymphocyte proliferation assay was carried out using the BrdU method. ELISA was used to measure the levels of IFN-γ, IL-2, IL-4, IL-10, IL-12, and IL-17 cytokines, total IgG, as well as IgG1 and IgG2a subtypes in serum samples. Our findings showed that mice receiving the NLX/alum-adjuvanted vaccine exhibited increased antibody levels compared with other groups. In addition, there was a considerable difference in the levels of IgG1, IgG2a, IFN-γ, IL-2, IL-10, IL-12, and IL-17 in mice receiving the NLX/alum-adjuvanted vaccine as compared with other groups. The NLX/alum mixture, as an adjuvant, may have a positive effect on the induction of multi-cytokine responses, as well as the increased level of IL-10, showing its higher immunogenicity with a higher immunoregulatory mechanism.

Expansion of GARP-Expressing CD4+CD25-FoxP3+ T Cells and SATB1 Association with Activation and Coagulation in Immune Compromised HIV-1-Infected Individuals in South Africa

Although antiretroviral treatment lowers the burden of human immunodeficiency virus (HIV)-related disease, it does not always result in immunological recovery. This manifests as persistent chronic inflammation, immune activation or exhaustion that can promote the onset of co-morbidities. As the exact function of regulatory T (Treg) cells in HIV remains unclear, this cross-sectional study investigated three expression markers (Forkhead box protein P3 [FOXP3], glycoprotein A repetitions predominant [GARP], special AT-rich sequence binding protein 1 [SATB1]) and compared their expansion between CD4⁺CD25^- and CD4⁺CD25⁺⁺ T cells. Age-matched study subjects were recruited (Western Cape, South Africa) and sub-divided: HIV-negative subjects (n = 12), HIV-positive naïve treated (n = 22), HIV-positive treated based on CD4 count cells/µL (CD4 > 500 and CD4 < 500) (n = 34) and HIV-treated based on viral load (VL) copies/mL (VL < 1000 and VL > 1000) (n = 34). Markers of immune activation (CD38) and coagulation (CD142) on T cells (CD8) were assessed by flow cytometry together with FOXP3, GARP and SATB1 expression on CD4⁺CD25^- and CD4⁺CD25⁺⁺ T cells. Plasma levels of interleukin-10 (IL-10; anti-inflammatory marker), IL-6 (inflammatory marker) and D-dimer (coagulation marker) were assessed. This study revealed three major findings in immuno-compromised patients with virological failure (CD4 < 500; VL > 1000): (1) the expansion of the unconventional Treg cell subset (CD4⁺CD25^-FOXP3⁺) is linked with disease progression markers; (2) increased GARP expression in the CD4⁺CD25^- and CD4⁺CD25⁺⁺ subsets; and (3) the identification of a strong link between CD4⁺CD25^-SATB1⁺ cells and markers of immune activation (CD8⁺CD38⁺) and coagulation (CD8⁺CD142⁺ and D-dimer).

The Architecture of Circulating Immune Cells Is Dysregulated in People Living With HIV on Long Term Antiretroviral Treatment and Relates With Markers of the HIV-1 Reservoir, Cytomegalovirus, and Microbial Translocation

Long-term changes in the immune system of successfully treated people living with HIV (PLHIV) remain incompletely understood. In this study, we assessed 108 white blood cell (WBC) populations in a cohort of 211 PLHIV on stable antiretroviral therapy and in 56 HIV-uninfected controls using flow cytometry. We show that marked differences exist in T cell maturation and differentiation between PLHIV and HIV-uninfected controls: PLHIV had reduced percentages of CD4+ T cells and naïve T cells and increased percentages of CD8+ T cells, effector T cells, and T helper 17 (Th17) cells, together with increased Th17/regulatory T cell (Treg) ratios. PLHIV also exhibited altered B cell maturation with reduced percentages of memory B cells and increased numbers of plasmablasts. Determinants of the T and B cell composition in PLHIV included host factors (age, sex, and smoking), markers of the HIV reservoir, and CMV serostatus. Moreover, higher circulating Th17 percentages were associated with higher plasma concentrations of interleukin (IL) 6, soluble CD14, the gut homing chemokine CCL20, and intestinal fatty acid binding protein (IFABP). The changes in circulating lymphocytes translated into functional changes with reduced interferon (IFN)- γ responses of peripheral blood mononuclear cells to stimulation with Candida albicans and Mycobacterium tuberculosis. In conclusion, this comprehensive analysis confirms the importance of persistent abnormalities in the number and function of circulating immune cells in PLHIV on stable treatment.

Long-Term Suppressive cART Is Not Sufficient to Restore Intestinal Permeability and Gut Microbiota Compositional Changes

Background: We explored the long-term effects of cART on markers of gut damage, microbial translocation, and paired gut/blood microbiota composition, with a focus on the role exerted by different drug classes.

Methods: We enrolled 41 cART naïve HIV-infected subjects, undergoing blood and fecal sampling prior to cART (T0) and after 12 (T12) and 24 (T24) months of therapy. Fifteen HIV-uninfected individuals were enrolled as controls. We analyzed: (i) T-cell homeostasis (flow cytometry); (ii) microbial translocation (sCD14, EndoCab, 16S rDNA); (iii) intestinal permeability and damage markers (LAC/MAN, I-FABP, fecal calprotectin); (iv) plasma and fecal microbiota composition (alpha- and beta-diversity, relative abundance); (v) functional metagenome predictions (PICRUSt).

Results: Twelve and twenty four-month successful cART resulted in a rise in EndoCAb (p = 0.0001) and I-FABP (p = 0.039) vis-à-vis stable 16S rDNA, sCD14, calprotectin and LAC/MAN, along with reduced immune activation in the periphery. Furthermore, cART did not lead to substantial modifications of microbial composition in both plasma and feces and metabolic metagenome predictions. The stratification according to cART regimens revealed a feeble effect on microbiota composition in patients on NNRTI-based or INSTI-based regimens, but not PI-based regimens.

Conclusions: We hereby show that 24 months of viro-immunological effective cART, while containing peripheral hyperactivation, exerts only minor effects on the gastrointestinal tract. Persistent alteration of plasma markers indicative of gut structural and functional impairment seemingly parallels enduring fecal dysbiosis, irrespective of drug classes, with no effect on metabolic metagenome predictions.

Gut epithelial impairment, microbial translocation and immune system activation in inflammatory bowel disease-associated spondyloarthritis

OBJECTIVES

Gut microbiota has been widely reported to be involved in systemic inflammation through microbial translocation and T cell activation in several diseases. In this work we aimed to investigate bacterial infiltration and epithelial impairment in the gut of patients with IBD-associated SpA (SpA-IBD), as well as the relationship of microbial translocation with immune system activation and their putative role in the pathogenesis of joint inflammation in IBD patients.

METHODS

Tight-junction proteins (TJPs) occludin and claudin-1/-4 and bacteria were assessed by real-time PCR analysis and immunohistochemical staining of the ileum. Intestinal fatty acid binding protein (I-FABP), lipopolysaccharides (LPS), soluble CD14 (sCD14), sclerostin and anti-sclerostin antibodies (anti-sclerostin-IgG) were assayed with ELISAs and peripheral mononuclear blood cells with flow cytometry. LPS and sCD14 were used in vitro to stimulate a human osteoblast cell line.

RESULTS

Compared with IBD, ileal samples from SpA-IBD patients showed bacterial infiltration, epithelial damage and downregulation of TJPs. In sera, they showed higher serum levels of I-FABP, LPS, sCD14 (the latter correlating with sclerostin and anti-sclerostin-IgG) and higher CD80+/CD163+ and lower CD14+ mononuclear cells. In vitro experiments demonstrated that only the LPS and sCD14 synergic action downregulates sclerostin expression in osteoblast cells.

CONCLUSION

SpA-IBD patients are characterized by gut epithelium impairment with consequent translocation of microbial products into the bloodstream, immune system activation and an increase of specific soluble biomarkers. These findings suggest that gut dysbiosis could be involved in the pathogenesis of SpA-IBD and it could hopefully prompt the use of these biomarkers in the follow-up and management of IBD patients.

Association of Plasma Soluble Vascular Cell Adhesion Molecule-1 and sCD14 With Mortality in HIV-1-Infected West African Adults With High CD4 Counts

BACKGROUND

Several biomarkers of inflammation and coagulation were reported to be associated with HIV disease progression in different settings. In this article, we report the association between 11 biomarkers and medium-term mortality in HIV-infected West African adults.

METHODS

In Temprano ANRS 12136, antiretroviral therapy (ART)-naive HIV-infected adults with high CD4 counts were randomly assigned either to start ART immediately or defer ART until the World Health Organization criteria were met. Participants who completed the 30-month trial follow-up were invited to participate in a posttrial phase. The posttrial phase end point was all-cause death. We used multivariate Cox proportional models to analyze the association between baseline plasma biomarkers [IL-1ra, IL-6, soluble vascular cell adhesion molecule 1 (sVCAM-1), sCD14, D-dimer, fibrinogen, IP-10, sCD163, albumin, high-sensitivity C-reactive protein, and 16S rDNA] and all-cause death in the Temprano participants randomized to defer ART.

RESULTS

Four hundred seventy-seven patients (median age 35 years, 78% women, and median CD4 count: 379 cells/mm) were randomly assigned to defer starting ART until the World Health Organization criteria were met. The participants were followed for 2646 person-years (median 5.8 years). In the follow-up, 89% of participants started ART and 30 died. In the multivariate analysis adjusted for the study center, sex, baseline CD4 count, isoniazid preventive therapy, plasma HIV-1 RNA, peripheral blood mononuclear cell HIV-1 DNA, and ART, the risk of death was significantly associated with baseline sVCAM-1 (≥1458 vs. <1458: adjusted hazard ratio 2.57, 95% confidence interval: 1.13 to 5.82) and sCD14 (≥2187 vs. <2187: adjusted hazard ratio 2.79, interquartile range 1.29-6.02) levels.

CONCLUSIONS

In these sub-Saharan African adults with high CD4 counts, pre-ART plasma sVCAM-1 and sCD14 levels were independently associated with mortality.

Innate immune mechanisms to oral pathogens in oral mucosa of HIV-infected individuals

A crucial aspect of mucosal HIV transmission is the interaction between HIV, the local environmental milieu and immune cells. The oral mucosa comprises many host cell types including epithelial cells, CD4 + T cells, dendritic cells and monocytes/macrophages, as well as a diverse microbiome predominantly comprising bacterial species. While the oral epithelium is one of the first sites exposed to HIV through oral-genital contact and nursing infants, it is largely thought to be resistant to HIV transmission via mechanisms that are still unclear. HIV-1 infection is also associated with predisposition to secondary infections, such as tuberculosis, and other diseases including cancer. This review addresses the following questions that were discussed at the 8th World Workshop on Oral Health and Disease in AIDS held in Bali, Indonesia, 13 September –15 September 2019: (a) How does HIV infection affect epithelial cell signalling? (b) How does HIV infection affect the production of cytokines and other innate antimicrobial factors, (c) How is the mucosal distribution and function of immune cells altered in HIV infection? (d) How do T cells affect HIV (oral) pathogenesis and cancer? (e) How does HIV infection lead to susceptibility to TB infections?

Early Antiretroviral Therapy Prevents Viral Infection of Monocytes and Inflammation in Simian Immunodeficiency Virus-Infected Rhesus Macaques

Despite early antiretroviral therapy (ART), treatment interruption is associated with viral rebound, indicating early viral reservoir (VR) seeding and absence of full eradication of human immunodeficiency virus type 1 (HIV-1) that may persist in tissues. Herein, we address the contributing role of monocytes in maintaining VRs under ART, since these cells may represent a source of viral dissemination due to their ability to replenish mucosal tissues in response to injury. To this aim, monocytes with classical (CD14⁺), intermediate (CD14⁺ CD16⁺), and nonclassical (CD16⁺) phenotypes and CD4⁺ T cells were sorted from the blood, spleen, and intestines of untreated and early-ART-treated simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs) before and after ART interruption. Cell-associated SIV DNA and RNA were quantified. We demonstrated that in the absence of ART, monocytes were productively infected with replication-competent SIV, especially in the spleen. Reciprocally, early ART efficiently (i) prevented the establishment of monocyte VRs in the blood, spleen, and intestines and (ii) reduced systemic inflammation, as indicated by changes in interleukin-18 (IL-18) and IL-1 receptor antagonist (IL-1Ra) plasma levels. ART interruption was associated with a rebound in viremia that led to the rapid productive infection of both CD4⁺ T cells and monocytes. Altogether, our results reveal the benefits of early ART initiation in limiting the contribution of monocytes to VRs and SIV-associated inflammation.IMPORTANCE Despite the administration of antiretroviral therapy (ART), HIV persists in treated individuals and ART interruption is associated with viral rebound. Persistent chronic immune activation and inflammation contribute to disease morbidity. Whereas monocytes are infected by HIV/SIV, their role as viral reservoirs (VRs) in visceral tissues has been poorly explored. Our work demonstrates that monocyte cell subsets in the blood, spleen, and intestines do not significantly contribute to the establishment of early VRs in SIV-infected rhesus macaques treated with ART. By preventing the infection of these cells, early ART reduces systemic inflammation. However, following ART interruption, monocytes are rapidly reinfected. Altogether, our findings shed new light on the benefits of early ART initiation in limiting VR and inflammation.

HIV and the Gut Microbiota: Composition, Consequences, and Avenues for Amelioration

PURPOSE OF REVIEW

We discuss recent advances in understanding of gut bacterial microbiota composition in HIV-infected subjects and comment on controversies. We discuss the putative effects of microbiota shifts on systemic inflammation and HIV disease progression and potential mechanisms, as well as ongoing strategies being developed to modulate the gut microbiota in humans for amelioration of infectious and inflammatory diseases.

RECENT FINDINGS

Lifestyle and behavioral factors relevant to HIV infection studies have independent effects on the microbiota. Microbial metabolism of immunomodulatory compounds and direct immune stimulation by translocation of microbes are putative mechanisms contributing to HIV disease. Fecal microbiota transplantation, microbial enzyme inhibition, phage therapy, and rationally selected probiotic cocktails have emerged as promising strategies for microbiota modulation. Numerous surveys of the HIV gut microbiota matched for lifestyle factors suggest consistent shifts in gut microbiota composition among HIV-infected subjects. Evidence exists for a complex pathogenic role of the gut microbiota in HIV disease progression, warranting further study.

Microbiota in viral infection and disease in humans and farm animals

The influence of the microbiota on viral infection susceptibility and disease outcome is undisputable although varies among viruses. The purpose of understanding the interactions between microbiota, virus, and host is to identify practical, effective, and safe approaches that target microbiota for the prevention and treatment of viral diseases in humans and animals, as currently there are few effective and reliable antiviral therapies available. The initial step for achieving this goal is to gather clinical evidences, focusing on the viral pathogens-from human and animal studies-that have already been shown to interact with microbiota. The subsequent step is to identify mechanisms, through experimental evidences, to support the development of translational applications that target microbiota. In this chapter, we review evidences of virus infections altering microbiota and of microbiota enhancing or suppressing infectivity, altering host susceptibility to certain viral diseases, and influencing vaccine immunogenicity in humans and farm animals.

Gut Microbiome, Short-Chain Fatty Acids, and Mucosa Injury in Young Adults with Human Immunodeficiency Virus Infection

BACKGROUND

HIV progression is characterized by immune activation and microbial translocation from the gut. Short-chain fatty acids (SCFAs) are essential for gut homeostasis. Decreased intestinal SCFAs play a role in rapid HIV progression.

AIMS

To compare the SCFA profile, intestinal microbiome, and intestinal mucosal injury between patients with HIV (but not AIDS) and healthy controls.

METHODS

This was a prospective study of 15 patients without AIDS and 10 controls conducted between July 2016 and January 2017 at the Institute of Dermatology and Venereology (Sichuan Academy of Medical Sciences). Stool specimens were collected to analyze the microbiome and SCFAs. Blood I-FABP and D-lactate (gut injury markers) were measured as well as T cells in HIV-positive patients. Intestinal mucosa was observed by colonoscopy.

RESULTS

Rikenellaceae, Microbacteriaceae, Roseburia, Lachnospiraceae, Alistipes, and Ruminococcaceae were decreased, while Moraxellaceae and Psychrobacter were increased in HIV-positive patients. Butyric acid (p = 0.04) and valeric acid (p = 0.03) were reduced in HIV-positive patients. Colonoscopy revealed no visible damage in all subjects. There were no differences in I-FABP and D-lactate between groups. Butyric and valeric acids mainly positively correlated with Rikenellaceae, Ruminococcaceae, Alistipes, Roseburia, and Lachnospiraceae. CD8+ cells were positively correlated with Proteobacteria. CD4+ cells, and CD4/CD8 were negatively correlated with acetic acid. CD8+ cells were positively correlated with valeric acid.

CONCLUSION

The differences in the distribution of intestinal flora between HIV-infected and healthy individuals, especially some SCFAs, suggest that there is already a predisposition to intestinal mucosa damage in HIV-infected individuals.

Different pattern of stool and plasma gastrointestinal damage biomarkers during primary and chronic HIV infection

Introduction

Primary HIV infection (PHI) is the initial phase after HIV acquisition characterized by high viral replication, massive inflammatory response and irreversible immune-damage, particularly at the gastrointestinal level. In this study we aimed to characterize the dynamics of gastrointestinal damage biomarkers during the different phases of HIV infection and assess their association with HIV-disease markers and their accuracy to differentiate PHI from chronic HIV infection (CHI).

Methods

PHI-individuals (n = 57) were identified as HIV-seronegative/HIV-RNA positive and were followed up for one year at the Manhiça District Hospital in Mozambique. Ten plasma and 12 stool biomarkers were quantified by Luminex or ELISA and levels were compared to CHI-naive (n = 26), CHI on antiretroviral-treatment (ART; n = 30) and HIV-uninfected individuals (n = 58). Regression models adjusted by time point were used to estimate the association of the biomarkers with HIV-disease markers. Receiver operating curves were compared for the best accuracy to distinguish PHI from CHI.

Results

Soluble (s)CD14 was significantly associated with the CD4/CD8 ratio (P < 0.05) and viremia levels (P < 0.0001) during PHI. Plasma zonulin and stool lactoferrin were significantly higher in PHI as compared to CHI-individuals (P < 0.05). Plasma zonulin demonstrated the best accuracy to identify PHI among HIV-infected individuals (AUC = 0.85 [95% CI 0.75–0.94]). Using a cutoff value of plasma zonulin ≥ 8.75 ng/mL the model identified PHI with 87.7% sensitivity (95% CI 76.3–94.9) and 69.2% specificity (95% CI 48.2–85.7). An adjusted multivariate model including age, plasma zonulin and sCD14 further increased the classification performance (AUC = 0.92 [95% CI 0.86–0.99]).

Conclusions

While the stool biomarkers did not provide any predictive ability to distinguish PHI from CHI-individuals, plasma sCD14 and zonulin were significantly associated with HIV-disease markers and PHI identification, respectively. These inflammatory biomarkers may be useful to monitor changes in gastrointestinal integrity during HIV infection.

Increased monocyte activation with age among HIV-infected long term non-progressor children: implications for early treatment initiation

OBJECTIVES

The key to newer therapeutic and eradication approaches often lies in understanding slow disease progression in HIV infection. The paediatric population has been poorly studied in this regard. We aimed to describe a cohort of perinatally infected long-term nonprogressor (LTNP) children living with HIV in India and to evaluate the immune biomarkers of disease progression.

METHODS

LTNPs (ART-naïve, with a CD4 count ≥ 500 cells/μL at age ≥ 7 years) among the cohort of HIV-infected children were identified and monitored longitudinally, and their CD4 T-cell counts and plasma viral loads were measured every 6 months. The plasma monocyte/macrophage activation markers, namely soluble CD14 (sCD14), soluble CD163 (sCD163) and interferon-inducible protein-10 (IP-10) were measured by enzyme-linked immunosorbent assay (ELISA) in LTNPs and progressors. The Mann-Whitney U-test was used to compare the two groups and P values < 0.05 were considered statistically significant. Spearman's rank or Pearson's correlation coefficient (r) was calculated to determine the associations between variables.

RESULTS

Among 378 children living with HIV-1 surveyed in our cohort, 40 (10.6%) were LTNPs. Longitudinal analysis of the LTNP data showed that both CD4 count and viral load declined significantly with age (P < 0.0001 for both). Plasma sCD14 levels were significantly (P < 0.005) higher in progressors and sCD163 levels were significantly (P < 0.0001) higher in LTNPs.

CONCLUSIONS

The prevalence of LTNPs in our cohort of perinatally infected children living with HIV was 10.6%. We observed a trend for associations between the increasing sCD163 monocyte/macrophage activation marker levels, declining CD4 counts and the gradual loss of nonprogressor status with age in the LTNPs. These findings underscore the need for early antiretroviral therapy in those children with proven slow disease progression.

Impact of HIV-ART on the restoration of Th17 and Treg cells in blood and female genital mucosa

The aim of this study was to evaluate the effectiveness of antiretroviral treatment (ART) on the proportion and functions of Th17 and Treg cells in peripheral blood and female genital tract (FGT) respectively. To this aim, samples from 41 HIV-neg, 33 HIV+ ART-naïve and 32 HIV+ ART+ subjects were obtained. In peripheral blood, altered Th17 and Th17/Treg proportions were normalized in HIV+ ART+, but certain abnormal Treg and activated T-cell proportions were still observed. In FGT, abnormal patterns of secretion for Th17-related cytokines were observed in cervical mononuclear cells (CMCs) from HIV+ women, even in those from HIV+ ART+, compared to the HIV-neg group. Moreover, these altered patterns of secretion were associated with diminished levels of CXCL5 and CXCL1 chemokines and with an immunoregulatory skew in the CCL17/CCL20 ratio in ectocervix samples of these women. Finally, ART did not restore proportions of Th17-precursor cells with gut-homing potential in PBMCs, and positive correlations between these cells and the levels of IL-17F and IL-21 production by CMCs may suggest that a better homing of these cells to the intestine could also imply a better restoration of these cells in the female genital tract. These results indicate that antiretroviral treatment did not restore Th17-related immune functions completely at the female mucosal level.

Microbial Translocation Does Not Drive Immune Activation in Ugandan Children Infected With HIV

Objective

Immune activation is associated with morbidity and mortality during human immunodeficiency virus (HIV) infection, despite receipt of antiretroviral therapy (ART). We investigated whether microbial translocation drives immune activation in HIV-infected Ugandan children.

Methods

Nineteen markers of immune activation and inflammation were measured over 96 weeks in HIV-infected Ugandan children in the CHAPAS-3 Trial and HIV-uninfected age-matched controls. Microbial translocation was assessed using molecular techniques, including next-generation sequencing.

Results

Of 249 children included, 142 were infected with HIV; of these, 120 were ART naive, with a median age of 2.8 years (interquartile range [IQR], 1.7-4.0 years) and a median baseline CD4+ T-cell percentage of 20% (IQR, 14%-24%), and 22 were ART experienced, with a median age of 6.5 years (IQR, 5.9-9.2 years) and a median baseline CD4+ T-cell percentage of 35% (IQR, 31%-39%). The control group comprised 107 children without HIV infection. The median increase in the CD4+ T-cell percentage was 17 percentage points (IQR, 12-22 percentage points) at week 96 among ART-naive children, and the viral load was <100 copies/mL in 76% of ART-naive children and 91% of ART-experienced children. Immune activation decreased with ART use. Children could be divided on the basis of immune activation markers into the following 3 clusters: in cluster 1, the majority of children were HIV uninfected; cluster 2 comprised a mix of HIV-uninfected children and HIV-infected ART-naive or ART-experienced children; and in cluster 3, the majority were ART naive. Immune activation was low in cluster 1, decreased in cluster 3, and persisted in cluster 2. Blood microbial DNA levels were negative or very low across groups, with no difference between clusters except for Enterobacteriaceae organisms (the level was higher in cluster 1; P < .0001).

Conclusion

Immune activation decreased with ART use, with marker clustering indicating different activation patterns according to HIV and ART status. Levels of bacterial DNA in blood were low regardless of HIV status, ART status, and immune activation status. Microbial translocation did not drive immune activation in this setting.

Clinical Trials Registration

ISRCTN69078957.

Cytokine Changes in Maternal Peripheral Blood Correlate With Time-to-Delivery in Pregnancies Complicated by Premature Prelabor Rupture of the Membranes

Premature prelabor rupture of the membranes (PPROM) causes one-third of preterm births worldwide and is most likely caused by subclinical intrauterine infection and/or inflammation. We proposed that women with systemic inflammation at the time of PPROM would have shorter latency. Peripheral blood samples were collected from 20 singleton pregnant women with PPROM between 23 ± 1 and 33 ± 6 weeks. The first sample was drawn within 48 hours of admission, followed by weekly blood draws until delivery. Pregnancies complicated with acute chorioamnionitis, preeclampsia, intrauterine growth restriction, obesity, substance abuse, and chronic maternal disease were excluded. Twenty uncomplicated, gestational age-matched pregnancies served as controls. Plasma concentration of 39 cytokines was measured longitudinally using Luminex assays to investigate their value as predictive biomarkers of latency. Women with PPROM exhibited significantly lower plasma concentration of interferon-γ-inducible protein 10-Chemokine (c-x-c motif; IP10/CXCL10), Chemokine (c-x-c motif) Ligand 9 (MIG/CXCL9), Platelet-derived growth factor BB (PDGFbb), and cutaneous T cell-attracting chemokine, also known as CCL27/CCL27 than controls at admission but significantly elevated interleukin (IL)1RA, tumor necrosis factor α, monocyte chemotactic protein-1/CCL2 at delivery compared to admission. Women with PPROM who delivered within 7 days had significantly lower plasma concentration of anti-inflammatory cytokine IL1RA than those with latency periods >7 days. The IL1RA and endotoxin activity in conjunction with clinical parameters results in excellent prediction of latency to delivery (area under the receiver-operating characteristic curve = 0.91). We concluded that higher levels of anti-inflammatory cytokines in women with PPROM were associated with increased latency until delivery, likely due to counterbalancing of proinflammatory load. When used in conjunction with other predictive characteristics of time until delivery, cytokines may further assist clinical decision-making and optimize pregnancy outcomes in women with PPROM.

Imbalance between T helper 17 and regulatory T cell subsets plays a significant role in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease that is characterized by fibrosis, inflammation, and vasculopathy of the skin and internal organs. The etiopathogenesis of SSc remains unclear. However, the pivotal role of T lymphocytes with an aberrant immune response in SSc is well established. Among T cells, IL-17-producing helper T (Th17) cell and regulatory T (Treg) cell subsets have recently been found to play crucial roles in SSc pathogenesis. Generally speaking, Th17 cell subsets up-regulate inflammation, fibrosis, and autoimmunity, which are present in SSc, while Treg cell subsets have an immunosuppressive function and resist the immunological performance of Th17 cells. Up-to-date evidence has pointed out that the imbalance and abnormal functions of Th17/Treg cells may contribute to SSc. Therefore, this review aims to summarize the current understanding of the vital cytokines and signaling pathways that are involved in Th17/Treg differentiation and functions, and their roles in the pathogenesis of SSc, thus providing novel insights about targeting the Th17/Treg balance as a potential therapy for SSc treatment in the near future.

Systemic DPP4 activity is reduced during primary HIV-1 infection and is associated with intestinal RORC+ CD4+ cell levels: a surrogate marker candidate of HIV-induced intestinal damage

INTRODUCTION

Combined anti-retroviral therapy (cART) transformed HIV-1 from a deadly disease into a chronic infection, but does not cure HIV infection. It also does not fully restore HIV-induced gut damage unless administered extremely early after infection. Additional biomarkers are needed to evaluate the capacity of therapies aimed at HIV remission/cure to restore HIV-induced intestinal immune damage and limit chronic inflammation. Herein, we aimed to identify a systemic surrogate marker whose levels would reflect gut immune damage such as intestinal Th17 cell loss starting from primary HIV-1 infection.

METHODS

Biomarker discovery approaches were performed in four independent cohorts, covering HIV-1 primary and chronic infection in 496 naïve or cART-treated patients (Amsterdam cohort (ACS), ANRS PRIMO, COPANA and CODEX cohorts). The concentration and activity of soluble Dipeptidylpeptidase 4 (sDPP4) were quantified in the blood from these patients, including pre- and post-infection samples in the ACS cohort. For quantification of DPP4 in the gut, we utilized two non-human primate models, representing pathogenic (macaque) and non-pathogenic (African green monkey) SIV infection. Four gut compartments were analysed in each animal model (ileum, jejunum, colon and rectum) for quantification of DPP4, RORC and TBX21 gene expression in sorted CD4+ cells. To analyse if sDPP4 levels increase when Th17 cells were restored, we quantified sDPP4 in plasma from SIV-infected macaques treated with IL-21.

RESULTS

We showed that sDPP4 levels were strongly decreased in primary HIV-1 infection. Strikingly, sDPP4 levels in primary HIV-1 infection predicted time to AIDS. They were not increased by cART in chronic HIV-1 infection (median 36 months on cART). In the gut of SIV-infected non-human primates, DPP4 mRNA was higher in CD4+ than CD4- leucocytes. DPP4 specifically correlated with RORC expression, a Th17 marker, in CD4+ cells from the intestine. We further demonstrated that sDPP4 activity levels were increased in animals treated with IL-21 and that this increase was associated with restoration of the Th17 compartment and reduced inflammation. Furthermore, DPP4 mRNA levels in small intestine CD4+ cells positively correlated with circulating DPP4 activity.

CONCLUSION

These data provide evidence that blood sDPP4 levels could be useful as a correlate for HIV-induced intestinal damage.

The anti-caspase inhibitor Q-VD-OPH prevents AIDS disease progression in SIV-infected rhesus macaques

Apoptosis has been proposed as a key mechanism responsible for CD4+ T cell depletion and immune dysfunction during HIV infection. We demonstrated that Q-VD-OPH, a caspase inhibitor, inhibits spontaneous and activation-induced death of T cells from SIV-infected rhesus macaques (RMs). When administered during the acute phase of infection, Q-VD-OPH was associated with (a) reduced levels of T cell death, (b) preservation of CD4+/CD8+ T cell ratio in lymphoid organs and in the gut, (c) maintenance of memory CD4+ T cells, and (d) increased specific CD4+ T cell response associated with the expression of cytotoxic molecules. Although therapy was limited to the acute phase of infection, Q-VD-OPH-treated RMs showed lower levels of both viral load and cell-associated SIV DNA as compared with control SIV-infected RMs throughout the chronic phase of infection, and prevented the development of AIDS. Overall, our data demonstrate that Q-VD-OPH injection in SIV-infected RMs may represent an adjunctive therapeutic agent to control HIV infection and delaying disease progression to AIDS.

Immune activation despite preserved CD4 T cells in perinatally HIV-infected children and adolescents

BACKGROUND

HIV disease progresses more rapidly in children than adults with mortality rates exceeding 50% by 2 years of age without antiretroviral therapy (ART) in sub-Saharan Africa. Recent World Health Organization (WHO) guidelines recommend universal treatment for all living persons with HIV, yet there is limited supporting evidence in pediatric populations. The objective of this study was to determine whether CD4 cell counts reflect immunological markers associated with disease progression in ART naïve perinatally-infected HIV+ children and adolescents and their response to ART.

METHODS

PBMC and plasma samples were collected from 71 HIV negative and 132 HIV+ children (65 ART naïve and 67 on ART) between ages 1-19 years from Mombasa, Kenya. Untreated HIV+ subjects were sub-categorized by high or low CD4 T cell counts. Immune activation markers CD38, HLA-DR and Ki67 were analyzed by flow cytometry. Plasma soluble CD14 (sCD14) was quantified by ELISA.

RESULTS

HIV-infected children and adolescents with preserved CD4 cell counts had depleted CD4 percentages and CD4:CD8 ratios, and high immune activation levels. ART initiation rapidly and persistently reversed T cell activation, but failed to normalize CD4:CD8 ratios and plasma sCD14 levels.

CONCLUSIONS

Diminished CD4 percentages and CD4:CD8 ratios along with profound immune activation occur independent of CD4 cell count thresholds in ART naïve HIV+ children and adolescents. Immediate ART initiation, as recommended in the most recent WHO guidelines may protect them from pathologic sequelae associated with persistent inflammation.

Determinant Variables, Enteric Pathogen Burden, Gut Function and Immune-related Inflammatory Biomarkers Associated With Childhood Malnutrition: A Prospective Case-Control Study in Northeastern Brazil

Malnutrition results in serious consequences for growth and cognitive development in children. We studied select child and maternal biologic factors, socioeconomic factors, enteric pathogenic burden and gut function biomarkers in 402 children 6-24 months of age in Northeastern Brazil. In this prospective case-control study, not being fed colostrum [odds ratio (OR): 3.29, 95% confidence interval (CI): 1.73-6.26], maternal age ≥18 years (OR: 1.88, 95% CI: 1.10-3.22) and no electric fan (OR: 2.46, 95% CI: 1.22-4.96) or bicycle (OR: 1.80, 95% CI: 1.10-2.95) in the household were positively associated, and higher birth weight (OR: 0.27, 95% CI: 0.19-0.38), larger head circumference (OR: 0.74, 95% CI: 0.66-0.82) and shortness of breath in the last 2 weeks (OR: 0.49, 95% CI: 0.27-0.90) were negatively associated with malnutrition. Subclinical enteric pathogen infections were common, and enteroaggregative Escherichia coli infections were more prevalent in malnourished children (P = 0.045). Biomarkers such as the lactulose-mannitol test, myeloperoxidase, neopterin and calprotectin were highly elevated in both malnourished and nourished children. Nourished children had a better systemic immune response than the malnourished children, as detected by elevated serum amyloid A-1 and soluble cluster of differentiation protein 14 biomarkers (P < 0.001). Serum amyloid A-1 and soluble cluster of differentiation protein 14 were also associated with better nutritional Z scores. Neonatal, maternal and socioeconomic factors were associated with malnutrition in children. There was a substantial subclinical enteric pathogen burden, particularly with enteroaggregative E. coli, in malnourished children.

Exploring the link between innate immune activation and thymic function by measuring sCD14 and TRECs in HIV patients living in Belgium

Microbial translocation is now viewed as a central event in the pathogenesis of chronic inflammation during HIV infection. Thymic function failure is another crucial factor involved in HIV disease progression. The goal of this study was to explore the hypothesis of potential links between microbial translocation and thymic function in HIV-1 patients living in Belgium. The extent of microbial translocation was assessed through the measurement of soluble CD14 (sCD14). T-cell receptor excision circles (sjTRECs and dβTRECs) were used as a measure of thymic function. Data were collected from 75 HIV-infected patients. Simple and complex linear regressions were done to analyze the link between these two processes. We found a statistically relevant negative correlation between thymopoiesis (sjTREC) and sCD14 level (p = 0.004). These results suggest a link between thymic function failure, microbial translocation and innate immune activation.

Potential Role of Vδ2+ γδ T Cells in Regulation of Immune Activation in Primary HIV Infection

Although conventional regulatory T cells (Tregs) are sufficient in controlling low residual T-cell activation in ART-treated patients, they are not efficient in controlling exaggerated immune activation associated with high levels of HIV replication in primary HIV infection (PHI). Our previous data suggested that double negative (DN) T cells including mainly γδ DN T cells play a role in the control of immune activation in PHI. Since γδ T cells are capable of exerting regulatory functions, we investigated their implication as Tregs in PHI as well as chronic HIV infection (CHI). In a cross-sectional study of 58 HIV-infected patients, in the primary and the chronic phase either ART-treated or untreated (UT), we analyzed phenotype and cytokine production of γδ T cells using flow cytometry. Cytokine production was assessed following in vitro stimulation with isopentenyl pyrophosphate or plate-bound anti-CD3/anti-CD28 monoclonal antibodies. We found that the proportion of γδ T cells negatively correlated with CD8 T-cell activation in PHI patients. Furthermore, we found that in these patients, the Vδ2 receptor bearing (Vδ2⁺) γδ T cells were strongly activated, exhibited low terminal differentiation, and produced the anti-inflammatory cytokine, TGF-β. In contrast, in UT-CHI, we observed a remarkable expansion of γδ T cells, where the Vδ2⁺ γδ T cells comprised of an elevated proportion of terminally differentiated cells producing high levels of IFN-γ but very low levels of TGF-β. We also found that this loss of regulatory feature of γδ T cells in CHI was a lasting impairment as we did not find recovery of TGF-β production even in ART-CHI patients successfully treated for more than 5 years. Our data therefore suggest that during the primary HIV infection, Vδ2⁺ γδ T cells may act as Tregs controlling immune activation through production of TGF-β. However, in CHI, γδ T cells transform from an anti-inflammatory into pro-inflammatory cytokine profile and participate in sustenance of immune activation.

Microbial translocation is correlated with HIV evolution in HIV-HCV co-infected patients

Microbial translocation (MT) is characterized by bacterial products passing into the blood through the gut barrier and is a key phenomenon in the pathophysiology of Human Immunodeficiency Virus (HIV) infection. MT is also associated with liver damage in Hepatitis C Virus (HCV) patients. The aim of the study was to assess MT in plasma of HIV-HCV co-infected patients. 16S rDNA (16 S Ribosomal DNA subunit) marker and other markers of MT such as Lipopolysaccharide (LPS)-binding protein (LBP), soluble CD14 (sCD14), intestinal fatty acid binding protein (I-FABP) were used. Clinical, biological and immunological characteristics of the population were studied in order to correlate them with the intensity of the MT. We demonstrate that indirect markers of MT, LBP and CD14s, and a marker of intestinal permeability (I-FABP) are significantly higher in HIV-HCV co-infected patients than in healthy controls (17.0 vs 2.6 μg/mL, p < 0.001; 1901.7 vs 1255.0 ng/mL, p = 0.018); 478.3 vs 248.1 pg/mL, p < 0.001, respectively), while a direct marker of MT (16S rDNA copies) is not different between these two populations. However, plasma 16S rDNA was significantly higher in co-infected patients with long-standing HIV infections (RGM = 1.47 per 10 years, CI95% = [1.04:2.06], p = 0.03). Our findings show that in HIV-HCV co-infected patients, plasma 16S rDNA levels, directly reflecting MT, seem to be linked to the duration of HIV infection, while elevated levels of LBP and sCD14 reflect only a persistence of immune activation. The levels of these markers were not correlated with HCV evolution.

Terminal differentiation of T cells is strongly associated with CMV infection and increased in HIV-positive individuals on ART and lifestyle matched controls

HIV-1-positive individuals on successful antiretroviral therapy (ART) are reported to have higher rates of age-associated non-communicable comorbidities (AANCCs). HIV-associated immune dysfunction has been suggested to contribute to increased AANCC risk. Here we performed a cross-sectional immune phenotype analysis of T cells in ART-treated HIV-1-positive individuals with undetectable vireamia (HIV-positives) and HIV-1-negative individuals (HIV-negatives) over 45 years of age. In addition, two control groups were studied: HIV negative adults selected based on lifestyle and demographic factors (Co-morBidity in Relation to AIDS, or COBRA) and unselected age-matched donors from a blood bank. Despite long-term ART (median of 12.2 years), HIV-infected adults had lower CD4⁺ T-cell counts and higher CD8⁺ T-cell counts compared to well-matched HIV-negative COBRA participants. The proportion of CD38⁺HLA-DR⁺ and PD-1⁺ CD4⁺ T-cells was higher in HIV-positive cohort compared to the two HIV-negative cohorts. The proportion CD57⁺ and CD27⁻CD28⁻ cells of both CD4⁺ and CD8⁺ T-cells in HIV-positives was higher compared to unselected adults (blood bank) as reported before but this difference was not apparent in comparison with well-matched HIV-negative COBRA participants. Multiple regression analysis showed that the presence of an increased proportion of terminally differentiated T cells was strongly associated with CMV infection. Compared to appropriately selected HIV-negative controls, HIV-positive individuals on ART with long-term suppressed viraemia exhibited incomplete immune recovery and increased immune activation/exhaustion. CMV infection rather than treated HIV infection appears to have more consistent effects on measures of terminal differentiation of T cells.

Immune activation in prolonged cART-suppressed HIV patients is comparable to that of healthy controls

Sustained immune activation during chronic HIV infection is considered to augment co-morbidity and mortality. Effective combination antiretroviral therapy (cART) has shown to dampen immune activation especially during the first year cART, but the effects of long-term cART in patients without major comorbidities remains under-investigated. We performed a comprehensive analysis including cellular, intracellular and plasma biomarkers to study the effect of cART on immune parameters in 5 groups of 10 HIV patients. All patients were without major co-morbidities and grouped based on cART duration (0, 1, 3, 5, and 10 years). We included 10 matched healthy controls for comparison. Our data show that after the first year of cART, no additional effect on the level of inflammatory markers is observed in HIV infected patients without major co morbidities. Residual immune activation status in well-treated HIV-infection is similar to levels observed in healthy controls.

Gag-Specific CD8 T-Cell Proliferation Is Associated With Higher Peripheral Blood Levels of Transforming Growth Factor-β and Gut-Homing T Cells in Youths Perinatally Infected With Human Immunodeficiency Virus-1: The ANRS-EP38-IMMIP Study

Background

Gag-specific T lymphocytes play a key role in the control of human immunodeficiency virus (HIV) replication. Their restoration will be important for future reservoir targeting strategies. In this study, we aimed to identify immune correlates of Gag-specific CD8 T-cell proliferation in youths with perinatally acquired HIV-1 infection.

Methods

The ANRS-EP38-IMMIP study included youths of 15 to 24 years of age. Fifty-three were taking combination anti-retroviral therapy and aviremic at the time of the study and had undergone valid 5-6-carboxyfluorescein diacetate succimidyl ester-based flow cytometry T-cell proliferation assays. Plasma analytes were quantified by enzyme-linked immunosorbent assay or multiplex assays. Peripheral blood cells were phenotyped by flow cytometry. Logistic regression was used to study the association between Gag-specific T-cell proliferation and immune markers.

Results

Patients with Gag-specific CD8 T-cell proliferation had higher levels of plasma transforming growth factor (TGF)-β1, a lower proportion of naive cells among regulatory T cells (Tregs), and higher percentages of CD4 and CD8 T cells expressing the α₄β₇ integrin or CD161 molecule than those without a Gag-specific response. These associations were significant based on analyses including potential confounders.

Conclusions

Preserved Gag-specific CD8 T-cell proliferation was associated with higher TGF-β1 levels and increased percentages of T cells with a gut-homing phenotype at least 15 years after HIV infection during the perinatal period.

From Wasting to Obesity: The Contribution of Nutritional Status to Immune Activation in HIV Infection

The impact of human immunodeficiency virus (HIV) infection on innate and adaptive immune activation occurs in the context of host factors, which serve to augment or dampen the physiologic response to the virus. Independent of HIV infection, nutritional status, particularly body composition, affects innate immune activation through a variety of conditions, including reduced mucosal barrier defenses and microbiome dysbiosis in malnutrition and the proinflammatory contribution of adipocytes and stromal vascular cells in obesity. Similarly, T-cell activation, proliferation, and cytokine expression are reduced in the setting of malnutrition and increased in obesity, potentially due to adipokine regulatory mechanisms restraining energy-avid adaptive immunity in times of starvation and exerting a paradoxical effect in overnutrition. The response to HIV infection is situated within these complex interactions between host nutritional health and immunologic function, which contribute to the varied phenotypes of immune activation among HIV-infected patients across a spectrum from malnutrition to obesity.

Prostaglandin E2 As a Modulator of Viral Infections

Viral infections are a major cause of infectious diseases worldwide. Inflammation and the immune system are the major host defenses against these viral infection. Prostaglandin E2 (PGE2), an eicosanoid generated by cyclooxygenases, has been shown to modulate inflammation and the immune system by regulating the expression/concentration of cytokines. The effect of PGE2 on viral infection and replication is cell type- and virus-family-dependent. The host immune system can be modulated by PGE2, with regards to immunosuppression, inhibition of nitrogen oxide (NO) production, inhibition of interferon (IFN) and apoptotic pathways, and inhibition of viral receptor expression. Furthermore, PGE2 can play a role in viral infection directly by increasing the production and release of virions, inhibiting viral binding and replication, and/or stimulating viral gene expression. PGE2 may also have a regulatory role in the induction of autoimmunity and in signaling via Toll-like receptors. In this review the known effects of PGE2 on the pathogenesis of various infections caused by herpes simplex virus, rotavirus, influenza A virus and human immunodeficiency virus as well the therapeutic potential of PGE2 are discussed.

Interleukin-1 receptor antagonist, a biomarker of response to anti-TB treatment in HIV/TB co-infected patients

OBJECTIVES

Despite the high frequency of tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) in human immunodeficiency virus (HIV)/TB co-infected patients, no diagnostic test is available. Here, we investigated whether monocyte/macrophage activation markers can predict TB-IRIS occurrence and if they are modulated by anti-TB treatment.

METHODS

Frozen plasma was obtained from 127 HIV/TB co-infected adults naïve for antiretroviral therapy, enrolled in the CAMELIA trial, 36 of whom developed TB-IRIS. Concentrations of IL-1Ra, sCD14, and sCD163 were measured at anti-TB treatment onset (baseline), after 8 weeks of anti-TB treatment and at TB-IRIS time.

RESULTS

At baseline, IL-1Ra and sCD14 concentrations were similar in TB-IRIS and non-IRIS patients. sCD163 concentrations, although significantly higher in TB-IRIS patients, did not remain associated with TB-IRIS occurrence in multivariate analysis. At the time of TB-IRIS, patients displayed higher concentrations of IL-1Ra (p = 0.002) and sCD14 (p < 0.001). The most striking result was the significant decrease in IL-1Ra after 8 weeks of anti-TB treatment (median reduction: -63% (p < 0.0001)).

CONCLUSIONS

None of the biomarkers tested was associated with TB-IRIS occurrence. However, repeated measurement of IL-1Ra could help for the diagnosis of TB-IRIS. The substantial reduction of IL-1Ra under treatment suggests that IL-1Ra could be a surrogate biomarker of anti-TB treatment response in HIV-infected patients.

Interleukin-1 receptor antagonist: an early immunomodulatory cytokine induced by porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) infection poorly induces pro-inflammatory cytokines (IL-1, IL-6 and TNF-α) and type I IFN production during the early phase of infection. Our microarray analysis indicated strong upregulation of the IL1RA gene in type 2 PRRSV -infected monocyte-derived dendritic cells. Interleukin-1 receptor antagonist (IL-1Ra) is an early inhibitory cytokine that suppresses pro-inflammatory cytokines and T-lymphocyte responses. To investigate the induction of IL-1Ra by PRRSV, monocyte-derived dendritic cells were cultured with type 2 PRRSV or other swine viruses. PRRSV increased both IL1RA gene expression and IL-1Ra protein production in the culture. The enhanced production of IL-1Ra was further confirmed in PRRSV-cultured PBMC and PRRSV-exposed pigs by flow cytometry. Myeloid cell population appeared to be the major IL-1Ra producer both in vitro and in vivo. In contrast to the type 2 PRRSV, the highly pathogenic (HP)- PRRSV did not upregulate IL1RA gene expression in vitro. To determine the kinetics of PRRSV-induced IL1RA gene expression in relation to other pro-inflammatory cytokine genes, PRRSV-negative pigs were vaccinated with a commercially available type 2 modified-live PRRS vaccine or intranasally inoculated with HP-PRRSV. In modified-live PRRS vaccine pigs, upregulation of IL1RA, but not IL1B and IFNA, gene expression was observed from 2 days post- vaccination. Consistent with the in vitro findings, upregulation of IL1RA gene expression was not observed in the HP-PRRSV-infected pigs throughout the experiment. This study identified IL-1Ra as an early immunomodulatory mediator that could be involved in the immunopathogenesis of PRRSV infections.

Bacterial translocation aggravates CCl4-induced liver cirrhosis by regulating CD4+ T cells in rats

Bacterial translocation (BT) is thought to play an important role in the development of liver cirrhosis, but the mechanisms have not been fully explored. This study aims to investigate the distribution of Treg (CD3⁺CD4⁺CD25⁺Foxp3⁺), Th17 (CD3⁺CD4⁺IL-17⁺), and Th1 (CD3⁺CD4⁺IFN-γ⁺) cells in the intestinal lamina propria, liver and blood and to explore their relationships with BT. Cirrhotic rats with ascites were induced by CCl₄. We found that there were lower levels of total protein and albumin, lower albumin/globulin ratio, lower body weight and higher spleen weight and ascites volume in cirrhotic rats with than without BT. We found that BT may cause increase of Treg cells in the proximal small intestine and decrease of Th17 cells in the whole intestine and blood in cirrhotic rats. It may also aggravate the CCl₄-induced decrease in Th1 cells in the whole intestine, liver, caecum, and blood and the CCl₄-induced increase in Th17 cells in the liver and Tregs in the distal small intestine, colon, and liver. Our data suggest that BT may aggravate liver injury and decrease liver function via an interaction with CD4⁺ T Cells. The results of this study may be helpful for the development of new treatments for liver cirrhosis.

Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16INK4a or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection

OBJECTIVES

As the HIV-infected population ages, the role of cellular senescence and inflammation on co-morbid conditions and pharmacotherapy is increasingly of interest. p16INK4a expression, a marker for aging and senescence in T-cells, is associated with lower intracellular concentrations of endogenous nucleotides (EN) and nucleos(t)ide reverse transcriptase inhibitors (NRTIs). This study expands on these findings by determining whether inflammation is contributing to the association of p16INK4a expression with intracellular metabolite (IM) exposure and endogenous nucleotide concentrations.

METHODS

Samples from 73 HIV-infected adults receiving daily tenofovir/emtricitabine (TFV/FTC) with either efavirenz (EFV) or atazanavir/ritonavir (ATV/r) were tested for p16INK4a expression, and plasma cytokine and intracellular drug concentrations. Associations between p16INK4a expression and cytokine concentrations were assessed using maximum likelihood methods, and elastic net regression was applied to assess whether cytokines were predictive of intracellular metabolite/endogenous nucleotide exposures.

RESULTS

Enrolled participants had a median age of 48 years (range 23-73). There were no significant associations between p16INK4a expression and cytokines. Results of the elastic net regression showed weak relationships between IL-1Ra and FTC-triphosphate and deoxyadenosine triphosphate exposures, and MIP-1β, age and TFV-diphosphate exposures.

CONCLUSIONS

In this clinical evaluation, we found no relationships between p16INK4a expression and cytokines, or cytokines and intracellular nucleotide concentrations. While inflammation is known to play a role in this population, it is not a major contributor to the p16INK4a association with decreased IM/EN exposures in these HIV-infected participants.

Immune Activation at Sites of HIV/TB Co-Infection Contributes to the Pathogenesis of HIV-1 Disease

Systemic immune activation is critical to the pathogenesis of HIV-1 disease, and is accentuated in HIV/TB co-infected patients. The contribution of immune activation at sites of HIV/TB co-infection to viral activity, CD4 T cell count, and productive HIV-1 infection remain unclear. In this study, we measured markers of immune activation both in pleural fluid and plasma, and in T cells in pleural fluid mononuclear cell (PFMC) and peripheral blood mononuclear cell (PBMC) in HIV/TB co-infected subjects. The relationship between soluble and T cell activation markers with viral load in pleural fluid and blood CD4 T cell count were assessed. The T cell phenotype and activation status of HIV-1 p24 + T cells in PFMC and PBMC from HIV/TB patients were determined. We found that T cell and macrophage-specific and non-specific soluble markers of immune activation, sCD27, sCD163, IL1Ra, and sCD14, were higher in pleural fluid as compared to plasma from HIV/TB co-infected subjects, and higher as compared to pleural fluid from TB mono-infected subjects. Intestinal fatty acid-binding protein, a marker of intestinal tract damage, in plasma from HIV/TB co-infected patients was not different than that in HIV+ subjects. Expression of HLADR and CD38 double positive (HLADR/CD38) on CD4 T cells, and CD69+ on CD8 T cells correlated with pleural fluid viral load, and inversely with blood CD4 T cell count. Higher expression of HLADR/CD38 and CCR5 on CD4 T cells, and HLADR/CD38 and CD69 on CD8 T cells in PFMC were limited to effector memory populations. HIV-1 p24+ CD8 negative (includes CD4 + and double negative T cells) effector memory T cells in PFMC had higher expression of HLADR/CD38, Ki67, and CCR5 compared to HIV-1 p24- CD8 negative PFMC. Cumulatively, these data indicate that sites of HIV/TB co-infection are the source of intense immune activation.

Preferential loss of gut-homing α4β7 CD4+ T cells and their circulating functional subsets in acute HIV-1 infection

Preferential infection and depletion of gut-homing α4β7 CD4+ T cells in the blood are observed in chronic HIV/SIV infection. The dynamic change in gut-homing α4β7 CD4+ T cells and their functional subsets during the acute stages of HIV-1 infection are less documented. Therefore, we conducted a cohort study to investigate whether acute HIV-1 infection induced abnormalities in gut-homing α4β7 CD4+ T cells and their functional subsets. We examined the frequency, absolute number, and functionality of gut-homing α4β7 CD4+ T cells in 26 acute HIV-1-infected patients compared with 20 healthy individuals. We found that circulating gut-homing α4β7 CD4+ T cells were preferentially depleted during acute HIV-1 infection and were positively correlated with absolute CD4+ T-cell count in blood. Notably, Th17 and Th1 cell subsets of gut-homing CD4+ T cells were also decreased, which resulted in an imbalance of T helper cells (Th1):regulatory T cells (Treg) and Treg:Th17 ratios. Gut-homing Th17 and Th1 cells were also positively correlated with the absolute number of total CD4+ T cells and gut-homing CD4+ T cells. The gut-homing Treg:Th17 ratio was inversely correlated with the CD4+ T-cell count. Taken together, the analyses of our acute HIV-1 cohort demonstrate that gut-homing α4β7 CD4+ T cells and their functional subsets were profoundly depleted during acute HIV-1 infection, which may have resulted in the persistent loss of circulating CD4+ T cells and an imbalance of Th1:Treg and Treg:Th17 ratios and contribute to HIV-1 disease pathogenesis.