Kinetics of microbial translocation markers in patients on efavirenz or lopinavir/r based antiretroviral therapy

Cardiovascular Disease and Thrombosis in HIV Infection

HIV infection has transitioned from an acute, fatal disease to a chronic one managed by antiretroviral therapy. Thus, the aging population of people living with HIV (PLWH) continues to expand. HIV infection results in a dysregulated immune system, wherein CD4+ T cells are depleted, particularly in the gastrointestinal tract, disrupting the gut epithelial barrier. Long-term HIV infection is associated with chronic inflammation through potentially direct mechanisms caused by viral replication or exposure to viral proteins and indirect mechanisms resulting from increased translocation of microbial products from the intestine or exposure to antiretroviral therapy. Chronic inflammation (as marked by IL [interleukin]-6 and CRP [C-reactive protein]) in PLWH promotes endothelial cell dysfunction and atherosclerosis. PLWH show significantly increased rates of cardiovascular disease, such as myocardial infarction (risk ratio, 1.79 [95% CI, 1.54-2.08]) and stroke (risk ratio, 2.56 [95% CI, 1.43-4.61]). In addition, PLWH have increased levels of the coagulation biomarker D-dimer and have a two to ten-fold increased risk of venous thromboembolism compared with the general population. Several small clinical trials analyzed the effect of different antithrombotic agents on platelet activation, coagulation, inflammation, and immune cell activation. Although some markers for coagulation were reduced, most agents failed to reduce inflammatory markers in PLWH. More studies are needed to understand the underlying mechanisms driving inflammation in PLWH to create better therapies for lowering chronic inflammation in PLWH. Such therapies can potentially reduce atherosclerosis, cardiovascular disease, and thrombosis rates in PLWH and thus overall mortality in this population.

Relevance of biomarkers indicating gut damage and microbial translocation in people living with HIV

The intestinal barrier has the daunting task of allowing nutrient absorption while limiting the entry of microbial products into the systemic circulation. HIV infection disrupts the intestinal barrier and increases intestinal permeability, leading to microbial product translocation. Convergent evidence has shown that gut damage and an enhanced level of microbial translocation contribute to the enhanced immune activation, the risk of non-AIDS comorbidity, and mortality in people living with HIV (PLWH). Gut biopsy procedures are invasive, and are not appropriate or feasible in large populations, even though they are the gold standard for intestinal barrier investigation. Thus, validated biomarkers that measure the degree of intestinal barrier damage and microbial translocation are needed in PLWH. Hematological biomarkers represent an objective indication of specific medical conditions and/or their severity, and should be able to be measured accurately and reproducibly via easily available and standardized blood tests. Several plasma biomarkers of intestinal damage, i.e., intestinal fatty acid-binding protein (I-FABP), zonulin, and regenerating islet-derived protein-3α (REG3α), and biomarkers of microbial translocation, such as lipopolysaccharide (LPS) and (1,3)-β-D-Glucan (BDG) have been used as markers of risk for developing non-AIDS comorbidities in cross sectional analyses and clinical trials, including those aiming at repair of gut damage. In this review, we critically discuss the value of different biomarkers for the estimation of gut permeability levels, paving the way towards developing validated diagnostic and therapeutic strategies to repair gut epithelial damage and to improve overall disease outcomes in PLWH.

Methadone use is associated with increased levels of sCD14, immune activation, and inflammation during suppressed HIV infection

Opioid use has negative effects on immune responses and may impair immune reconstitution in persons living with HIV (PLWH) infection undergoing antiretroviral treatment (ART). The effects of treatment with μ opioid receptor (MOR) agonists (e.g., methadone, MET) and antagonists (e.g., naltrexone, NTX) on immune reconstitution and immune activation in ART-suppressed PLWH have not been assessed in-depth. We studied the effects of methadone or naltrexone on measures of immune reconstitution and immune activation in a cross-sectional community cohort of 30 HIV-infected individuals receiving suppressive ART and medications for opioid use disorder (MOUD) (12 MET, 8 NTX and 10 controls). Plasma markers of inflammation and immune activation were measured using ELISA, Luminex, or Simoa. Plasma IgG glycosylation was assessed using capillary electrophoresis. Cell subsets and activation were studied using whole blood flow cytometry. Individuals in the MET group, but no in the NTX group, had higher plasma levels of inflammation and immune activation markers than controls. These markers include soluble CD14 (an independent predictor of morbidity and mortality during HIV infection), proinflammatory cytokines, and proinflammatory IgG glycans. This effect was independent of time on treatment. Our results indicate that methadone-based MOUD regimens may sustain immune activation and inflammation in ART-treated HIV-infected individuals. Our pilot study provides the foundation and rationale for future longitudinal functional studies of the impact of MOUD regimens on immune reconstitution and residual activation after ART-mediated suppression.

Endothelial activation is associated with intestinal epithelial injury, systemic inflammation and treatment regimen in children living with vertically acquired HIV-1 infection

BACKGROUND

Premature development of cardiovascular disease in children living with HIV-1 (CLWH) may be associated with compromised gut barrier function, microbial translocation, immune activation, systemic inflammation and endothelial activation. Biomarkers of these pathways may provide insights into pathogenesis of atherosclerotic disease in CLWH.

METHODS

This was a cross-sectional study of CLWH enrolled in the multicentre Early Pediatric Initiation-Canadian Child Cure Cohort (EPIC⁴ ) who were on antiretroviral therapy (ART) with undetectable viral load. Plasma biomarkers of intestinal epithelial injury [intestinal fatty acid binding protein-1 (IFABP)], systemic inflammation [tumour necrosis factor (TNF) and interleukin-6 (IL-6)] and endothelial activation [angiopoietin-2 (Ang2), soluble vascular endothelial growth factor-1 (sVEGFR1) and soluble endoglin (sEng)] were quantified by enzyme-linked immunosorbent assay. Correlation and factor analysis of biomarkers were used to examine associations between innate immune pathways.

RESULTS

Among 90 CLWH, 16% of Ang2, 15% of sVEGFR1 and 23% of sEng levels were elevated relative to healthy historic controls. Pairwise rank correlations between the three markers of endothelial activation were statistically significant (ρ = 0.69, ρ = 0.61 and ρ = 0.65, P < 0.001 for all correlations). An endothelial activation index, derived by factor analysis of the three endothelial biomarkers, was correlated with TNF (ρ = 0.47, P < 0.001), IL-6 (ρ = 0.60, P < 0.001) and intestinal fatty acid binding protein-1 (ρ = 0.67, P < 0.001). Current or past treatment with ritonavir-boosted lopinavir (LPV/r) was associated with endothelial activation (odds ratio = 5.0, 95% CI: 1.7-17, P = 0.0020).

CONCLUSIONS

Endothelial activation is prevalent in CLWH despite viral suppression with combination ART and is associated with intestinal epithelial injury, systemic inflammation and treatment with LPV/r.

Abnormal Levels of Some Biomarkers of Immune Activation Despite Very Early Treatment of Human Immunodeficiency Virus

BACKGROUND

Despite early antiretroviral therapy (ART), ART-suppressed people with human immunodeficiency virus (HIV) (PWH) remain at higher risk for infections and infection-related cancers than the general population. The immunologic pathways that remain abnormal in this setting, potentially contributing to these complications, are unclear.

METHODS

ART-suppressed PWH and HIV-negative controls, all cytomegalovirus seropositive and enriched for HIV risk factors, were sampled from an influenza vaccine responsiveness study. PWH were stratified by timing of ART initiation (within 6 months of infection [early ART] vs later) and nadir CD4+ T-cell count among later initiators. Between-group differences in kynurenine-tryptophan (KT) ratio, interferon-inducible protein 10, soluble CD14 and CD163, soluble tumor necrosis factor receptor 2, interleukin 6, and soluble urokinase plasminogen activator receptor were assessed after confounder adjustment.

RESULTS

Most participants (92%) were male, reflecting the demographics of early-ART initiators in San Francisco. Most biomarkers were higher among later-ART initiators. Participants in the early-ART group achieved near-normal soluble tumor necrosis factor receptor 2, interleukin 6, and soluble urokinase plasminogen activator receptor levels, but substantially higher KT ratio than those without HIV after confounder adjustment (P = .008). Soluble CD14, soluble CD163, and interferon-inducible protein 10 trended similarly.

CONCLUSIONS

While early-ART initiators restore near-normal levels of many inflammatory markers, the kynurenine pathway of tryptophan catabolism remains abnormally high. Because this pathway confers adaptive immune defects and predicts tuberculosis and cancer progression, this it may contribute to persistent risks of these complications in this setting.

High microbial translocation limits gut immune recovery during short-term HAART in the area with high prevalence of foodborne infection

BACKGROUND

Individuals residing in areas with high prevalence of foodborne infection could have a higher risk of gut microbial translocation which may affect monocyte activation, gut immune recovery and intestinal epithelial cell damage. We aimed to measure alterations in microbial translocation, monocyte activation, gut immune recovery, and intestinal epithelial cell damage in HAART treated individuals.

METHODS

A prospective, single-arm, longitudinal, cohort study was conducted among antiretroviral naïve HIV-1 infected Thai participants. All participants were in chronic stage of HIV-1 infection before starting HAART. Data and samples were collected prior to initiation of HAART and then after 24 and 48 weeks of HAART. Plasma biomarkers for microbial translocation (16S rDNA and LBP), monocyte activation (sCD14) and intestinal epithelial cell damage (I-FABP) were evaluated. We measured circulating gut-homing CD4⁺ T cells and circulating gut-homing Th17 cells to assess recoveries of gut immunity and gut immunity to microbial pathogens.

RESULTS

The kinetic studies showed no reduction in the levels of plasma 16S rDNA, sCD14 or I-FABP, significant decrease of plasma LBP level, and slow but significant increases in the frequencies of circulating gut-homing CD4⁺ T cells and circulating gut-homing Th17 cells during 48 weeks of HAART. Dividing participants into low and high microbial translocation (low and high MT) groups at baseline, both groups showed persistent plasma levels of 16S rDNA, sCD14 and I-FABP, and significantly decreased plasma level of LBP. The low MT group had significantly increased frequencies of circulating gut-homing CD4⁺ T cells and circulating gut-homing Th17 cells during 48 weeks of HAART but this was not observed in the high MT group.

CONCLUSIONS

We demonstrated persistent high microbial translocation, monocyte activation and intestinal epithelial cell damage with slow gut immune recovery during successful short-term HAART. Additionally, gut immune recovery was apparently limited by high microbial translocation. Our findings emphasize the adverse impact of high microbial translocation on gut immune recovery and the necessity of establishing a novel therapeutic intervention to inhibit microbial translocation.

Effect of Stopping Cotrimoxazole Preventive Therapy on Microbial Translocation and Inflammatory Markers Among Human Immunodeficiency Virus-Infected Ugandan Adults on Antiretroviral Therapy: The COSTOP Trial Immunology Substudy

BACKGROUND

Cotrimoxazole preventive therapy (CPT) in human immunodeficiency virus (HIV) infection is a World Health Organization-recommended standard of care in resource-limited settings, but the mechanism of CPT's beneficial effects is unclear. The COSTOP trial (ISRCTN44723643) evaluated the noninferiority of discontinuing CPT in stabilized patients on antiretroviral therapy. The COSTOP immunology substudy was conducted on a subset of COSTOP participants randomized to continue CPT (n = 86) or discontinue CPT (placebo, n = 86) as daily treatment for 1 year.

METHODS

We evaluated whether CPT reduces microbial translocation, indicated by the presence of bacterial lipopolysaccharide (LPS) and LPS control factors such as soluble CD14 (sCD14) and endotoxin core antibody (EndoCAb immunoglobulin M [IgM]) in plasma. Intestinal barrier damage as indicated by plasma intestinal fatty acid binding protein (IFABP), T-cell activation, and the inflammatory markers C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) were also evaluated.

RESULTS

We found no significant change in markers of microbial translocation (LPS, IFABP, sCD14, and T-cell activation), with decreased EndoCAb IgM. There was significant increase in inflammation markers (CRP and IL-6) after stopping CPT compared to those who continued CPT.

CONCLUSIONS

These results add to the evidence of immunological benefits of CPT among HIV-infected populations in resource-limited settings. However, no evidence of reducing microbial translocation was observed.

Lower Pretreatment Gut Integrity Is Independently Associated With Fat Gain on Antiretroviral Therapy

BACKGROUND

Fat accumulation and insulin resistance remain a threat to the success of antiretroviral therapy (ART). The role of gut dysfunction in metabolic complications associated with ART initiation is unclear.

METHODS

Human immunodeficiency virus (HIV)-infected ART-naive participants were randomized to tenofovir disoproxil fumarate/emtricitabine plus atazanavir/ritonavir, darunavir/ritonavir, or raltegravir (RAL). Changes in the gut integrity markers zonulin, lipopolysaccharide-binding protein (LBP), and intestinal fatty acid and ileal bile acid binding proteins (I-FABP and I-BABP) were assessed over 96 weeks. Wilcoxon rank-sum tests were used to compare changes between groups and linear regression models to quantify associations between gut markers, insulin resistance, body mass index (BMI), and visceral, subcutaneous, and total adipose tissue (VAT, SAT, and TAT).

RESULTS

: 90% were male and 48% were White non-Hispanic. The median age was 36 years, HIV-1 ribonucleic acid was 4.56 log10 copies/mL, and CD4 count was 338 cells/µL. An overall 1.7-fold increase in I-FABP was observed throughout 96 weeks, with no difference between arms. Zonulin levels increased with RAL compared to protease inhibitor-based regimens (week 96, P = .02); minimal changes in I-BABP or LBP levels were observed. Higher baseline I-FABP levels were associated with increases in VAT, TAT, and BMI (16%, 9%, and 2.5%, respectively; P < .04) over 96 weeks.

CONCLUSIONS

While ART induces changes in the markers of gut barrier dysfunction, the extent to which they improve or worsen the gut barrier function remains unclear. Nevertheless, markers of gut barrier dysfunction in ART-naive individuals predict increases in total and visceral abdominal fat with treatment initiation.

Cotrimoxazole reduces systemic inflammation in HIV infection by altering the gut microbiome and immune activation

Long-term cotrimoxazole prophylaxis reduces mortality and morbidity in HIV infection, but the mechanisms underlying these clinical benefits are unclear. Here, we investigate the impact of cotrimoxazole on systemic inflammation, an independent driver of HIV mortality. In HIV-positive Ugandan and Zimbabwean children receiving antiretroviral therapy, we show that plasma inflammatory markers were lower after randomization to continue (n = 144) versus stop (n = 149) cotrimoxazole. This was not explained by clinical illness, HIV progression, or nutritional status. Because subclinical enteropathogen carriage and enteropathy can drive systemic inflammation, we explored cotrimoxazole effects on the gut microbiome and intestinal inflammatory biomarkers. Although global microbiome composition was unchanged, viridans group Streptococci and streptococcal mevalonate pathway enzymes were lower among children continuing (n = 36) versus stopping (n = 36) cotrimoxazole. These changes were associated with lower fecal myeloperoxidase. To isolate direct effects of cotrimoxazole on immune activation from antibiotic effects, we established in vitro models of systemic and intestinal inflammation. In vitro cotrimoxazole had modest but consistent inhibitory effects on proinflammatory cytokine production by blood leukocytes from HIV-positive (n = 16) and HIV-negative (n = 8) UK adults and reduced IL-8 production by gut epithelial cell lines. Collectively we demonstrate that cotrimoxazole reduces systemic and intestinal inflammation both indirectly via antibiotic effects on the microbiome and directly by blunting immune and epithelial cell activation. Synergy between these pathways may explain the clinical benefits of cotrimoxazole despite high antimicrobial resistance, providing further rationale for extending coverage among people living with HIV in sub-Saharan Africa.

Immunological and Neurometabolite Changes Associated With Switch From Efavirenz to an Integrase Inhibitor

BACKGROUND

The biological mechanisms by which efavirenz (EFV) causes central nervous system (CNS) effects are unclear. The objective of this pilot study was to elucidate the mechanisms underlying these CNS effects by correlating well-described neuropsychological (NP) changes with neurometabolites and immunologic markers following switch off EFV.

SETTING

Two single-arm parallel switch studies among HIV-infected adults in Boston, USA, from 2015 to 2017.

METHODS

Twenty asymptomatic HIV-infected adults on EFV-containing regimens were switched to an integrase strand transfer inhibitor-based regimen for 8 weeks. NP assessments were conducted before and after switch and correlated with neurometabolite changes measured using magnetic resonance spectroscopy and immunological markers. All pre-EFV and post-EFV measures were evaluated using matched-paired analyses.

RESULTS

NP testing demonstrated improvement in the domains of mood, cognition, and sleep off EFV. Magnetic resonance spectroscopy revealed decreases in the neurometabolite glutathione level (P = 0.03), a marker of oxidative stress after switch. Inhibitory neuronal activity as reflected by gamma-amino butyric acid levels increased (P = 0.03), whereas excitatory neurotransmitters glutamine + glutamate (Glx) and aspartate decreased (P = 0.04, 0.001). Switching off EFV was also associated with changes in inflammatory markers; plasma markers sCD14 (P = 0.008) decreased, whereas I-FABP and TNFRI levels increased (P = 0.05, 0.03). Cellular markers CD4 and CD8 HLA-DR-/CD38 subsets both increased (P = 0.05, 0.02).

CONCLUSIONS

Even asymptomatic participants showed improvements in NP parameters when switched off EFV. These improvements were associated with decreased CNS oxidative stress and excitatory neuronal activity. Changes in immune activation biomarkers suggested overall decreased inflammation. EFV may exert CNS effects through oxidative and inflammatory pathways, providing insight into possible mechanisms of EFV neurotoxicity.

Inflammatory biomarker levels over 48 weeks with dual vs triple lopinavir/ritonavir-based therapy: Substudy of a randomized trial

Background

Inflammation has been associated with increased morbidity and mortality in HIV-positive patients. We compared inflammatory biomarkers with dual therapy using lopinavir/ritonavir plus lamivudine (LPV/r+3TC) versus triple therapy using LPV/r plus two nucleoside reverse transcriptase inhibitors (LPV/r+2NRTIs) in treatment-naïve HIV-positive adults.

Methods

This was a substudy among Argentinian participants in the randomized trial GARDEL. We measured hsCRP, IL-6, MCP-1, TNF, D-dimer and sCD14 from plasma collected at baseline, week 24 and week 48. Generalized estimating equations with an identity/logit link were used to model the average impact of dual versus triple therapy on each biomarker over time, controlling for baseline levels. Additional models estimated the average effect of virologic suppression on biomarker levels over time, adjusting for age, sex, and baseline CD4 count.

Results

Of 191 trial participants enrolled in Argentina, 172 had baseline and follow-up measurements and were included. Median (IQR) age was 35.5 (28.5, 45) years and CD4 cell count was 310 (219, 414) cells/mm³. Dual therapy was not associated with significantly different biomarker levels over 48 weeks relative to triple therapy. Virologic suppression was associated with statistically significant decreases in MCP-1, TNF and D-dimer levels and an unexpected increase in sCD14 levels. No change was observed in hsCRP or the proportion of participants with undetectable IL-6 levels.

Conclusions

In addition to having virologic non-inferiority, LPV/r+3TC dual therapy is generally associated with similar inflammatory biomarker levels over 48 weeks compared to LPV/r+2NRTIs triple therapy in treatment-naïve adults. Further study of dual treatment regimens is warranted.

Reduced Transplacental Transfer of Antimalarial Antibodies in Kenyan HIV-Exposed Uninfected Infants

BACKGROUND

Altered neonatal immune responses may contribute to the increased morbidity observed in HIV-exposed but uninfected (HEU) infants compared with HIV-unexposed uninfected (HUU) infants. We sought to examine the effects of prenatal HIV and malaria exposure on maternal and neonatal plasma cytokine profiles and transplacental antibody transfer.

METHODS

Forty-nine HIV+ and 50 HIV- women and their HIV-uninfected neonate pairs from Kenya were assessed. All HIV+ mothers received combination antiretroviral therapy. Maternal plasma and cord blood plasma samples at delivery were tested for 12 cytokines, total IgG, and IgG specific to 4 vaccine antigens and 14 Plasmodium falciparum antigens.

RESULTS

HIV+ mothers had lower levels of all 12 plasma cytokines at delivery compared with HIV- mothers, but there were no differences between HEU and HUU neonates. There were no differences in the cord-to-maternal ratios (CMRs) of vaccine-specific IgG between HIV+/HEU and HIV-/HUU maternal-neonate pairs. HIV+/HEU maternal-neonate pairs had significantly lower CMRs for 3 antimalarial IgGs-merozoite surface protein 9, circumsporozoite protein, and erythrocyte binding antigen 181-which remained statistically significant after adjustment for malaria in pregnancy.

CONCLUSIONS

In a cohort of optimally treated HIV-infected pregnant women, maternal HIV infection was associated with reduced transplacental transfer of antimalarial antibodies.

Richer gut microbiota with distinct metabolic profile in HIV infected Elite Controllers

Gut microbiota dysbiosis features progressive HIV infection and is a potential target for intervention. Herein, we explored the microbiome of 16 elite controllers (EC), 32 antiretroviral therapy naive progressors and 16 HIV negative controls. We found that the number of observed genera and richness indices in fecal microbiota were significantly higher in EC versus naive. Genera Succinivibrio, Sutterella, Rhizobium, Delftia, Anaerofilum and Oscillospira were more abundant in EC, whereas Blautia and Anaerostipes were depleted. Additionally, carbohydrate metabolism and secondary bile acid synthesis pathway related genes were less represented in EC. Conversely, fatty acid metabolism, PPAR-signalling and lipid biosynthesis proteins pathways were enriched in EC vs naive. The kynurenine pathway of tryptophan metabolism was altered during progressive HIV infection, and inversely associated with microbiota richness. In conclusion, EC have richer gut microbiota than untreated HIV patients, with unique bacterial signatures and a distinct metabolic profile which may contribute to control of HIV.

Brief Report: Differential Associations of Interleukin 6 and Intestinal Fatty Acid-Binding Protein With Progressive Untreated HIV-1 Infection in Rakai, Uganda

The significance of HIV-associated immune activation and microbial translocation in Sub-Saharan African population remains poorly defined. We assessed biomarkers of inflammation, microbial translocation, and cellular activation and found most factors elevated in Ugandan HIV-1 seroconverters compared with community-matched controls. In contrast to previous findings in Western cohorts, C-reactive protein, neopterin, and intestinal fatty acid binding protein were not elevated. Higher T-cell activation and IL-6 were associated with faster disease progression. Surprisingly, intestinal fatty acid binding protein, indicative of enterocyte turnover, was higher in slow than in fast progressors. These data suggest differential relationships among biomarkers of intestinal barrier integrity and innate immune activation between developed countries and Sub-Saharan Africa.

Inflammation, immune activation, and cardiovascular disease in HIV

Cardiovascular disease is one of the leading causes of morbidity and mortality in people living with HIV. Several epidemiological studies have shown an increased risk of myocardial infarction and stroke compared to uninfected controls. Although traditional risk factors contribute to this increased risk of cardiovascular disease, HIV-specific mechanisms likely also play a role. Systemic inflammation has been linked to cardiovascular disease in several populations suffering from chronic inflammation, including people living with HIV. Although antiretroviral therapy reduces immune activation, levels of inflammatory markers remain elevated compared to uninfected controls. The causes of this sustained immune response are likely multifactorial and incompletely understood. In this review, we summarize the evidence describing the relationship between inflammation and cardiovascular disease and discuss potential anti-inflammatory treatment options for cardiometabolic disease in people living with HIV.

Sex differences in soluble markers vary before and after the initiation of antiretroviral therapy in chronically HIV-infected individuals

OBJECTIVE

To evaluate differences in soluble inflammatory markers between chronically HIV-infected men and women, with or without cognitive impairment, and in response to treatment.

DESIGN

Soluble biomarkers were measured in cryopreserved plasma and cerebrospinal fluid (CSF) of 60 treatment-naïve individuals (25 men and 35 women) with chronic HIV infection and 18 HIV-uninfected controls (9 men and 9 women) from Thailand. Following enrollment, participants began combination antiretroviral therapy and were evaluated for expression of these markers after 48 weeks.

METHODS

Plasma and CSF levels of 19 soluble biomarkers (IFN-γ, TNFα, TNF-RII, IL-1α, IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-15, MCP-1, t-Tau, IP-10, neopterin, IFNα, I-FABP, and sCD14) were measured using either a multiparameter or standard ELISA assay.

RESULTS

Prior to combination antiretroviral therapy, women with impaired cognition had elevated levels of neopterin and TNF-RII compared with women with normal cognition in both the plasma and CSF; however, levels did not differ between cognitively impaired or normal men. In a secondary outcome-hypothesis generating analysis, sex differences were also pronounced in plasma levels of MCP-1, IL-10, I-FABP, and sCD14 in response to treatment. Neopterin, IP-10, TNFα, TNF-RII, IFNα, MCP-1, IL-8, I-FABP, and sCD14 plasma levels remained elevated following 48 weeks of therapy in both sexes compared with uninfected controls.

CONCLUSION

We provide evidence of sustained immune activation after 48 weeks of treatment and identify possible sex differences in biomarkers previously linked to cognitive impairment, chronic inflammation, and gut integrity that may contribute to immunological differences between sexes in relationship to disease progression and response to therapy.

Complexities of Gut Microbiome Dysbiosis in the Context of HIV Infection and Antiretroviral Therapy

Human immunodeficiency virus (HIV) infection is associated with an altered gut microbiome that is not consistently restored with effective antiretroviral therapy (ART). Interpretation of the specific microbiome changes observed during HIV infection is complicated by factors like population, sample type, and ART-each of which may have dramatic effects on gut bacteria. Understanding how these factors shape the microbiome during HIV infection (which we refer to as the HIV-associated microbiome) is critical for defining its role in HIV disease, and for developing therapies that restore gut health during infection.

Gut microbiota diversity predicts immune status in HIV-1 infection

OBJECTIVE

HIV-1 infection is characterized by altered intestinal barrier, gut microbiota dysbiosis, and systemic inflammation. We hypothesized that changes of the gut microbiota predict immune dysfunction and HIV-1 progression, and that antiretroviral therapy (ART) partially restores the microbiota composition.

DESIGN

An observational study including 28 viremic patients, three elite controllers, and nine uninfected controls. Blood and stool samples were collected at baseline and for 19 individuals at follow-up (median 10 months) during ART.

METHODS

Microbiota composition was determined by 16S rRNA sequencing (Illumina MiSeq). Soluble markers of microbial translocation and monocyte activation were analyzed by Limulus Amebocyte Lysate assay or ELISA.

RESULTS

Several alpha-diversity measures, including number of observed bacterial species and Shannon index, were significantly lower in viremic patients compared to controls. The alpha diversity correlated with CD4 T-cell counts and inversely with markers of microbial translocation and monocyte activation. In multivariate linear regression, for every age and sex-adjusted increase in the number of bacterial species, the CD4 T-cell count increased with 0.88 (95% confidence interval 0.35-1.41) cells/μl (P = 0.002). After introduction of ART, microbiota alterations persisted with further reduction in alpha diversity. The microbiota composition at the genus level was profoundly altered in viremic patients, both at baseline and after ART, with Prevotella reduced during ART (P < 0.007).

CONCLUSIONS

Gut microbiota alterations are closely associated with immune dysfunction in HIV-1 patients, and these changes persist during short-term ART. Our data implicate that re-shaping the microbiota may be an adjuvant therapy in patients commencing successful ART.

Effects of Co-Trimoxazole on Microbial Translocation in HIV-1-Infected Patients Initiating Antiretroviral Therapy

Microbial translocation (MT) contributes to immune activation during HIV-1 infection, and persists after initiation of antiretroviral therapy (ART). We investigated whether levels of MT markers are influenced by the use of co-trimoxazole (TMP-SMX) in HIV-1 patients. Plasma samples were obtained from HIV-1-infected patients initiating ART with (n=13) or without (n=13) TMP-SMX prophylaxis. Markers of MT [lipopolysaccharide-binding protein (LBP), lipopolysaccharide (LPS), soluble CD14 (sCD14), and intestinal fatty acid binding protein (I-FABP)] were assessed at baseline (BL), at 1 month, and at 1 year by the Limulus Amebocyte Lysate Assay or ELISA. BL levels of LBP were elevated in both categories of patients; they were highest in patients starting ART and TMP-SMX (median, μg/ml: 36.7 vs. 4.3, respectively, p=0.001) and correlated inversely with CD4(+) T cell counts (ρ=-0.65; p=0.005). Patients receiving ART and TMP-SMX had a significant reduction in LBP between BL and 1 year (median, μg/ml: 36.7 vs. 11.1; p=0.003). In contrast, levels of LPS at BL were lower in patients starting ART and TMP-SMX compared to those without TMP-SMX (median, pg/ml: 221 vs. 303 respectively; p=0.002) and did not change at 1 year. The increased BL levels of sCD14 had declined in both groups at 1 year. No difference in I-FABP levels was found between BL and 1 year. Concomitant use of ART and TMP-SMX reduces microbial translocation markers LBP and sCD14, probably due to its impact on the gut microbiota. Effective ART for 1 year does not restore gut-blood barrier dysfunction.

Low levels of microbial translocation marker LBP are associated with sustained viral response after anti-HCV treatment in HIV-1/HCV co-infected patients

BACKGROUND

Microbial translocation (MT) contributes to immune activation during HIV and HCV infections. We investigated the kinetics of MT markers during anti-HCV and anti-HIV treatments, and if baseline plasma levels of lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) could predict anti-HCV treatment outcome.

METHODS

Plasma from 78 HIV-infected patients was evaluated for LPS, LBP and sCD14. The patients starting anti-HCV treatment (with ongoing antiretroviral (ART) treatment) were categorized into sustained viral responders (SVR; n = 21) or non-responders (NR; n = 15) based on treatment outcome. ART starting subjects--were categorized into chronically HCV-infected (CH; n = 24) and mono-infected (HIV; n = 18), based on the HCV infection status. Samples were collected before start (at baseline) of pegylated-interferon-alpha/ribavirin (peg-IFN/RBV) or antiretroviral-therapy and two years after treatment start (at follow up). χ2-test, non-parametric statistics and logistic regression were applied to determine the associations with treatment response and changes of the soluble markers.

RESULTS

Plasma levels of LPS and sCD14 were elevated in all subjects before antiviral-treatment but remained unchanged at follow-up. Elevated levels of LBP were present in patients with HIV and HIV/HCV co-infection and were reduced by ART. Additionally, higher levels of LBP were present at baseline in NR vs. SVR. Higher levels of LBP at baseline were associated with non-response to peg-IFN/RBV treatment in both bivariate (OR: 0.19 95% CI: 0.06-0.31, p = 0.004) and multivariate analysis (OR: 1.43, 95% CI: 1.1-1.86, p = 0.07).

CONCLUSION

In HIV/HCV co-infected patients high baseline LBP levels are associated with non-response to peg-IFN/RBV therapy. Plasma LBP (decreased by ART) may be a more relevant MT marker than LPS and sCD14.

Immune activation is associated with increased gut microbial translocation in treatment-naive, HIV-infected children in a resource-limited setting

BACKGROUND

Gut damage resulting in microbial translocation (MT) is considered a major cause of immune activation (IA) in HIV infection, but data in children are limited, particularly in the absence of antiretroviral therapy.

METHODS

Sixty perinatally HIV-infected, antiretroviral therapy-naive children, aged 2-12 years, were evaluated for plasma levels of lipopolysaccharide, DNA sequences encoding bacterial 16 second ribosomal DNA (16S rDNA) and soluble CD14 concurrently with markers of CD4 and CD8 T-cell IA and immune exhaustion (IE), CD4 counts, and plasma viral load. At study entry, participants were classified into immune categories (ICs): IC1 (CD4% > 25), IC2 (CD4% 15-25), and IC3 (CD4% < 15). Age-matched HIV-uninfected children served as controls. Data were evaluated at study entry and at 12 months.

RESULTS

Levels of MT, IA, and IE were increased in patients as compared with controls, were highest in patients in IC3 group, and did not change over 12 months. MT products lipopolysaccharide and 16S rDNA correlated with each other and each correlated with plasma viral load, soluble CD14, and T-cell IA and IE. There was a correlation of IA with IE. CD4 counts and percentage were inversely correlated with MT products and underlying CD4 activation.

CONCLUSIONS

In a natural history cohort of HIV-infected children not on therapy, MT was more pronounced in the most severely immunocompromised patients and was associated with IA. Strategies to reduce MT may help to reduce IA and prevent CD4 depletion.

Contribution of intestinal barrier damage, microbial translocation and HIV-1 infection status to an inflammaging signature

Background

Systemic inflammation is a characteristic of both HIV-1 infection and aging (“inflammaging”). Intestinal epithelial barrier damage (IEBD) and microbial translocation (MT) contribute to HIV-associated inflammation, but their impact on inflammaging remains unclear.

Methods

Plasma biomarkers for IEBD (iFABP), MT (LPS, sCD14), T-cell activation (sCD27), and inflammation (hsCRP, IL-6) were measured in 88 HIV-1 uninfected (HIV^neg) and 83 treated, HIV-1-infected (HIV^pos) adults from 20–100 years old.

Results

Age positively correlated with iFABP (r = 0.284, p = 0.008), sCD14 (r = 0.646, p = <0.0001) and LPS (r = 0.421, p = 0.0002) levels in HIV^neg but not HIV^pos subjects. Age also correlated with sCD27, hsCRP, and IL-6 levels regardless of HIV status. Middle-aged HIV^pos subjects had elevated plasma biomarker levels similar to or greater than those of elderly HIV^neg subjects with the exception of sCD14. Clustering analysis described an inflammaging phenotype (IP) based on iFABP, sCD14, sCD27, and hsCRP levels in HIV^neg subjects over 60 years of age. The IP in HIV^neg subjects was used to develop a classification model that was applied to HIV^pos subjects to determine whether HIV^pos subjects under 60 years of age were IP+. HIV^pos IP+ subjects were similar in age to IP- subjects but had a greater risk of cardiovascular disease (CVD) based on Framingham risk score (p =  0.01).

Conclusions

We describe a novel IP that incorporates biomarkers of IEBD, MT, immune activation as well as inflammation. Application of this novel IP in HIV-infected subjects identified a group at higher risk of CVD.

Predictors of virologic response in persons who start antiretroviral therapy during recent HIV infection

OBJECTIVE

Despite evidence supporting antiretroviral therapy (ART) in recent HIV infection, little is known about factors that are associated with successful ART. We assessed demographic, virologic, and immunologic parameters to identify predictors of virologic response.

DESIGN

A 24-week observational study of ART on persons enrolled within 6 months of their estimated date of infection (EDI) evaluated baseline demographics and the collection of blood and gut specimens.

METHODS

Flow cytometry analyses of blood and gut lymphocytes allowed characterization of CD4 and CD8 T cells at study entry and end. Additional assessments included soluble CD14 (sCD14), lipopolysaccharide, CD4 T-cell counts, and HIV RNA levels.

RESULTS

Twenty-nine participants initiated ART, and 17 achieved undetectable HIV RNA by study end. A longer time from EDI to ART, older age, higher sCD14, lower proportions of central memory CD4 T cells, and higher proportions of activated CD8 T cells were associated with detectable viremia. Multivariable logistic regression found only older age and elevated sCD14 were independently associated with persistent viremia. Additionally, we observed that ART in recent infection did not result in discernible recovery of CD4 T cells in the gut.

CONCLUSION

In persons who started ART within 3-33 weeks from EDI, age and microbial translocation were associated with detectable HIV RNA. As observed in other cohorts, ART in recent infection did not improve proportions of total CD4 T cells in gut-associated lymphoid tissue (GALT). This lends support to further evaluate the use of more potent ART or regimens that protect the GALT in recent HIV infection.

Switch to raltegravir decreases soluble CD14 in virologically suppressed overweight women: the Women, Integrase and Fat Accumulation Trial

OBJECTIVES

Soluble CD14 (sCD14) is a monocyte activation marker associated with increased mortality in HIV infection. We assessed 48-week changes in sCD14 and other inflammatory biomarkers in virologically suppressed, HIV-infected women switching to raltegravir (RAL) from a protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor (NNRTI).

METHODS

HIV-infected women with central adiposity and HIV-1 RNA < 50 HIV-1 RNA copies/mL continued their thymidine-sparing nucleoside reverse transcriptase inhibitor (NRTI) backbone and were randomized to switch to open-label RAL at week 0 (immediate) or 24 (delayed). In an exploratory analysis, inflammatory biomarkers were measured on stored fasting plasma.

RESULTS

Of the 37 evaluable subjects, 78% were non-White; the median age was 43 years, the median body mass index (BMI) was 32 kg/m(2) and the median CD4 count was 558 cells/μL. At baseline, biomarker values were similar between groups. After 24 weeks, median sCD14 significantly declined in subjects switching to RAL [-21% (P < 0.001) vs. PI/NNRTI -5% (P = 0.49); between-group P < 0.01]. After 48 weeks, immediate-switch subjects maintained this decline and delayed-switch subjects experienced a similar decline following the switch to RAL (-10%; within-group P < 0.01). Immediate-switch subjects also experienced an initial increase in tumour necrosis factor (TNF)-α that was neither maintained after 48 weeks nor seen in delayed-switch subjects. After adjustment for multiple testing, only declines in sCD14 remained significant.

CONCLUSIONS

In this randomized trial of women with central adiposity, a switch to RAL from a PI or NNRTI was associated with a statistically significant decline in sCD14. Further studies are needed to determine whether integrase inhibitors have improved monocyte activation profiles compared with PIs and/or NNRTIs, and whether measured differences between antiretroviral agents translate to demonstrable clinical benefit.

Pattern of microbial translocation in patients living with HIV-1 from Vietnam, Ethiopia and Sweden

Introduction

The role of microbial translocation (MT) in HIV patients living with HIV from low- and middle-income countries (LMICs) is not fully known. The aim of this study is to investigate and compare the patterns of MT in patients from Vietnam, Ethiopia and Sweden.

Methods

Cross-sectional samples were obtained from treatment-naïve patients living with HIV-1 and healthy controls from Vietnam (n=83; n=46), Ethiopia (n=9492; n=50) and Sweden (n=51; n=19). Longitudinal samples were obtained from a subset of the Vietnamese (n=24) in whom antiretroviral therapy (ART) and tuberculostatics were given. Plasma lipopolysaccharide (LPS), sCD14 and anti-flagellin IgG were determined by the endpoint chromogenic Limulus Amebocyte Assay and enzyme-linked immunosorbent assay.

Results

All three biomarkers were significantly increased in patients living with HIV-1 from all countries as compared to controls. No differences were found between males and females. Vietnamese and Ethiopian patients had significantly higher levels of anti-flagellin IgG and LPS, as compared to Swedes. ART reduced these levels for the Vietnamese. Vietnamese patients given tuberculostatics at initiation of ART had significantly lower levels of anti-flagellin IgG and higher sCD14. The biomarkers were lower in Vietnamese who did not develop opportunistic infection.

Conclusions

Higher MT is common in patients living with HIV compared to healthy individuals, and in patients from LMICs compared to patients from a high-income country. Treatment with tuberculostatics decreased MT while higher levels of MT are associated with a poorer clinical outcome.

Microbial translocation in the pathogenesis of HIV infection and AIDS

In pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections, the translocation of microbial products from the gastrointestinal (GI) tract to portal and systemic circulation has been proposed as a major driver of the chronic immune activation that is associated with disease progression. Consistently, microbial translocation is not present in nonpathogenic SIV infections of natural host species. In vivo studies demonstrated that HIV/SIV-associated microbial translocation results from a series of immunopathological events occurring at the GI mucosa: (i) early and severe mucosal CD4(+) depletion, (ii) mucosal immune hyperactivation/persistent inflammation; (iii) damage to the integrity of the intestinal epithelium with enterocyte apoptosis and tight junction disruption; and (iv) subverted the gut microbiome, with a predominance of opportunistic bacteria. Direct in situ evidence of microbial translocation has been provided for SIV-infected rhesus macaques showing translocated microbial products in the intestinal lamina propria and distant sites. While the mechanisms by which microbial translocation causes immune activation remain controversial, a key pathogenic event appears to be innate immunity activation via Toll-like receptors and other pathogen recognition receptors. Accumulating clinical observations suggest that microbial translocation might affect HIV disease progression, response to therapy, and non-AIDS comorbidities. Given its detrimental effect on overall immunity, several interventions to prevent/block microbial translocation are currently under investigation as novel therapeutic agents for HIV/AIDS.