Reduced Levels of D-dimer and Changes in Gut Microbiota Composition After Probiotic Intervention in HIV-Infected Individuals on Stable ART

Fecal microbiota transplantation alters the proteomic landscape of inflammation in HIV: identifying bacterial drivers

BACKGROUND

Despite effective antiretroviral therapy, people with HIV (PWH) experience persistent systemic inflammation and increased morbidity and mortality. Modulating the gut microbiome through fecal microbiota transplantation (FMT) represents a novel therapeutic strategy. We aimed to evaluate proteomic changes in inflammatory pathways following repeated, low-dose FMT versus placebo.

METHODS

This double-masked, placebo-controlled pilot study assessed the proteomic impacts of weekly FMT versus placebo treatment over 8 weeks on systemic inflammation in 29 PWH receiving stable antiretroviral therapy (ART). Three stool donors with high Faecalibacterium and butyrate profiles were selected, and their individual stools were used for FMT capsule preparation. Proteomic changes in 345 inflammatory proteins in plasma were quantified using the proximity extension assay, with samples collected at baseline and at weeks 1, 8, and 24. Concurrently, we characterized shifts in the gut microbiota composition and annotated functions through shotgun metagenomics. We fitted generalized additive models to evaluate the dynamics of protein expression. We selected the most relevant proteins to explore their correlations with microbiome composition and functionality over time using linear mixed models.

RESULTS

FMT significantly reduced the plasma levels of 45 inflammatory proteins, including established mortality predictors such as IL6 and TNF-α. We found notable reductions persisting up to 16 weeks after the final FMT procedure, including in the expression of proteins such as CCL20 and CD22. We identified changes in 46 proteins, including decreases in FT3LG, IL6, IL10RB, IL12B, and IL17A, which correlated with multiple bacterial species. We found that specific bacterial species within the Ruminococcaceae, Succinivibrionaceae, Prevotellaceae families, and the Clostridium genus, in addition to their associated genes and functions, were significantly correlated with changes in inflammatory markers.

CONCLUSIONS

Targeting the gut microbiome through FMT effectively decreased inflammatory proteins in PWH, with sustained effects. These findings suggest the potential of the microbiome as a therapeutic target to mitigate inflammation-related complications in this population, encouraging further research and development of microbiome-based interventions. Video Abstract.

From dysbiosis to defense: harnessing the gut microbiome in HIV/SIV therapy

BACKGROUND

Although the microbiota has been extensively associated with HIV pathogenesis, the majority of studies, particularly those using omics techniques, are largely correlative and serve primarily as a basis for hypothesis generation. Furthermore, most have focused on characterizing the taxonomic composition of the bacterial component, often overlooking other levels of the microbiome. The intricate mechanisms by which the microbiota influences immune responses to HIV are still poorly understood. Interventional studies on gut microbiota provide a powerful tool to test the hypothesis of whether we can harness the microbiota to improve health outcomes in people with HIV.

RESULTS

Here, we review the multifaceted role of the gut microbiome in HIV/SIV disease progression and its potential as a therapeutic target. We explore the complex interplay between gut microbial dysbiosis and systemic inflammation, highlighting the potential for microbiome-based therapeutics to open new avenues in HIV management. These include exploring the efficacy of probiotics, prebiotics, fecal microbiota transplantation, and targeted dietary modifications. We also address the challenges inherent in this research area, such as the difficulty in inducing long-lasting microbiome alterations and the complexities of study designs, including variations in probiotic strains, donor selection for FMT, antibiotic conditioning regimens, and the hurdles in translating findings into clinical practice. Finally, we speculate on future directions for this rapidly evolving field, emphasizing the need for a more granular understanding of microbiome-immune interactions, the development of personalized microbiome-based therapies, and the application of novel technologies to identify potential therapeutic agents.

CONCLUSIONS

Our review underscores the importance of the gut microbiome in HIV/SIV disease and its potential as a target for innovative therapeutic strategies.

Effect of intake of probiotics and probiotic fermented foods on clinical outcomes among people living with HIV: A systematic review and meta-analysis

OBJECTIVE

The objective of the study was to determine the effect of probiotics and of probiotic-fermented foods on CD4 T-cell count, viral load, anaemia and body mass index (BMI) among people living with HIV (PLHIV).

METHODS

In this article, we systematically reviewed the evidence on the influence of probiotic supplementation on CD4 lymphocyte count, viral load and anaemia among PLHIV on highly active antiretroviral therapy (HAART) and those who were HAART-naive. Medical literature databases identified randomised trials and pre-post studies of probiotic supplementation and HIV-related outcomes, and random effects meta-analysis was conducted.

RESULTS

The preponderance of the evidence suggests that probiotic supplementation only improved CD4 lymphocyte count modestly, with quantitatively greater impact among individuals who were HAART-naive compared to HAART-experienced individuals. Probiotic supplementation improved CD4 lymphocyte count by 53 cells/mm3 (95% CI: 22 to 85) from 18 studies. Probiotic supplementation however reduced haemoglobin concentration by -2.1 g/L (95% CI: -4.0 to -0.2). Although viral load remain unchanged in HAART-experienced participants following probiotic supplementation, HAART-naïve participants saw a decrease in viral load. There were too few studies on the impact of probiotic supplementation on viral load (N = 1).

CONCLUSION

Probiotic supplementation resulted in a modest increase in CD4 lymphocyte count among HAART-naive individuals with no significant change observed among HAART-experienced ones. Viral load and haemoglobin concentration also remained unchanged following probiotic supplementation. Further rigorous and well-powered studies may evaluate the effect of probiotic supplementation on important clinical outcomes among PLHIV on HAART.

Probiotics and prebiotics: potential prevention and therapeutic target for nutritional management of COVID-19?

Scientists are working to identify prevention/treatment methods and clinical outcomes of coronavirus disease 2019 (COVID-19). Nutritional status and diet have a major impact on the COVID-19 disease process, mainly because of the bidirectional interaction between gut microbiota and lung, that is, the gut-lung axis. Individuals with inadequate nutritional status have a pre-existing imbalance in the gut microbiota and immunity as seen in obesity, diabetes, hypertension and other chronic diseases. Communication between the gut microbiota and lungs or other organs and systems may trigger worse clinical outcomes in viral respiratory infections. Thus, this review addresses new insights into the use of probiotics and prebiotics as a preventive nutritional strategy in managing respiratory infections such as COVID-19 and highlighting their anti-inflammatory effects against the main signs and symptoms associated with COVID-19. Literature search was performed through PubMed, Cochrane Library, Scopus and Web of Science databases; relevant clinical articles were included. Significant randomised clinical trials suggest that specific probiotics and/or prebiotics reduce diarrhoea, abdominal pain, vomiting, headache, cough, sore throat, fever, and viral infection complications such as acute respiratory distress syndrome. These beneficial effects are linked with modulation of the microbiota, products of microbial metabolism with antiviral activity, and immune-regulatory properties of specific probiotics and prebiotics through Treg cell production and function. There is a need to conduct clinical and pre-clinical trials to assess the combined effect of consuming these components and undergoing current therapies for COVID-19.

Intestinal bacteria-a powerful weapon for fungal infections treatment

The morbidity and mortality of invasive fungal infections are rising gradually. In recent years, fungi have quietly evolved stronger defense capabilities and increased resistance to antibiotics, posing huge challenges to maintaining physical health. Therefore, developing new drugs and strategies to combat these invasive fungi is crucial. There are a large number of microorganisms in the intestinal tract of mammals, collectively referred to as intestinal microbiota. At the same time, these native microorganisms co-evolve with their hosts in symbiotic relationship. Recent researches have shown that some probiotics and intestinal symbiotic bacteria can inhibit the invasion and colonization of fungi. In this paper, we review the mechanism of some intestinal bacteria affecting the growth and invasion of fungi by targeting the virulence factors, quorum sensing system, secreting active metabolites or regulating the host anti-fungal immune response, so as to provide new strategies for resisting invasive fungal infection.

The microbiota as a modulator of mucosal inflammation and HIV/HPV pathogenesis: From association to causation

Although the microbiota has largely been associated with the pathogenesis of viral infections, most studies using omics techniques are correlational and hypothesis-generating. The mechanisms affecting the immune responses to viral infections are still being fully understood. Here we focus on the two most important sexually transmitted persistent viruses, HPV and HIV. Sophisticated omics techniques are boosting our ability to understand microbiota-pathogen-host interactions from a functional perspective by surveying the host and bacterial protein and metabolite production using systems biology approaches. However, while these strategies have allowed describing interaction networks to identify potential novel microbiota-associated biomarkers or therapeutic targets to prevent or treat infectious diseases, the analyses are typically based on highly dimensional datasets -thousands of features in small cohorts of patients-. As a result, we are far from getting to their clinical use. Here we provide a broad overview of how the microbiota influences the immune responses to HIV and HPV disease. Furthermore, we highlight experimental approaches to understand better the microbiota-host-virus interactions that might increase our potential to identify biomarkers and therapeutic agents with clinical applications.

Walk on the wild side: SIV infection in African non-human primate hosts-from the field to the laboratory

HIV emerged following cross-species transmissions of simian immunodeficiency viruses (SIVs) that naturally infect non-human primates (NHPs) from Africa. While HIV replication and CD4+ T-cell depletion lead to increased gut permeability, microbial translocation, chronic immune activation, and systemic inflammation, the natural hosts of SIVs generally avoid these deleterious consequences when infected with their species-specific SIVs and do not progress to AIDS despite persistent lifelong high viremia due to long-term coevolution with their SIV pathogens. The benign course of natural SIV infection in the natural hosts is in stark contrast to the experimental SIV infection of Asian macaques, which progresses to simian AIDS. The mechanisms of non-pathogenic SIV infections are studied mainly in African green monkeys, sooty mangabeys, and mandrills, while progressing SIV infection is experimentally modeled in macaques: rhesus macaques, pigtailed macaques, and cynomolgus macaques. Here, we focus on the distinctive features of SIV infection in natural hosts, particularly (1): the superior healing properties of the intestinal mucosa, which enable them to maintain the integrity of the gut barrier and prevent microbial translocation, thus avoiding excessive/pathologic immune activation and inflammation usually perpetrated by the leaking of the microbial products into the circulation; (2) the gut microbiome, the disruption of which is an important factor in some inflammatory diseases, yet not completely understood in the course of lentiviral infection; (3) cell population shifts resulting in target cell restriction (downregulation of CD4 or CCR5 surface molecules that bind to SIV), control of viral replication in the lymph nodes (expansion of natural killer cells), and anti-inflammatory effects in the gut (NKG2a/c+ CD8+ T cells); and (4) the genes and biological pathways that can shape genetic adaptations to viral pathogens and are associated with the non-pathogenic outcome of the natural SIV infection. Deciphering the protective mechanisms against SIV disease progression to immunodeficiency, which have been established through long-term coevolution between the natural hosts and their species-specific SIVs, may prompt the development of novel therapeutic interventions, such as drugs that can control gut inflammation, enhance gut healing capacities, or modulate the gut microbiome. These developments can go beyond HIV infection and open up large avenues for correcting gut damage, which is common in many diseases.

Probiotic effects on immunity and microbiome in HIV-1 discordant patients

Background

Some HIV-1 infected patients are unable to completely recover normal CD4+ T-cell (CD4+) counts after achieving HIV-1 suppression with combined Antiretroviral Therapy (cART), hence being classified as immuno-discordant. The human microbiome plays a crucial role in maintaining immune homeostasis and is a potential target towards immune reconstitution.

Setting

RECOVER (NCT03542786) was a double-blind placebo-controlled clinical trial designed to evaluate if the novel probiotic i3.1 (AB-Biotics, Sant Cugat del Vallès, Spain) was able to improve immune reconstitution in HIV-1 infected immuno-discordant patients with stable cART and CD4+ counts <500 cells/mm3. The mixture consisted of two strains of L. plantarum and one of P. acidilactici, given with or without a fiber-based prebiotic.

Methods

71 patients were randomized 1:2:2 to Placebo, Probiotic or probiotic + prebiotic (Synbiotic), and were followed over 6 months + 3-month washout period, in which changes on systemic immune status and gut microbiome were evaluated. Primary endpoints were safety and tolerability of the investigational product. Secondary endpoints were changes on CD4+ and CD8+ T-cell (CD8+) counts, inflammation markers and faecal microbiome structure, defined by alpha diversity (Gene Richness), beta diversity (Bray-Curtis) and functional profile. Comparisons across/within groups were performed using standard/paired Wilcoxon test, respectively.

Results

Adverse event (AE) incidence was similar among groups (53%, 33%, and 55% in the Placebo, Probiotic and Synbiotic groups, respectively, the most common being grade 1 digestive AEs: flatulence, bloating and diarrhoea. Two grade 3 AEs were reported, all in the Synbiotic group: abdominal distension (possibly related) and malignant lung neoplasm (unrelated), and 1 grade 4 AE in the Placebo: hepatocarcinoma (unrelated). Synbiotic exposure was associated with a higher increase in CD4+/CD8+ T-cell (CD4/CD8) ratio at 6 months vs baseline (median=0.76(IQR=0.51) vs 0.72(0. 45), median change= 0.04(IQR=0.19), p = 0.03). At month 9, the Synbiotic group had a significant increase in CD4/CD8 ratio (0.827(0.55) vs 0.825(0.53), median change = 0.04(IQR=0.15), p= 0.02) relative to baseline, and higher CD4+ counts (447 (157) vs. 342(73) counts/ml, p = 0.03), and lower sCD14 values (2.16(0.67) vs 3.18(0.8), p = 0.008) than Placebo. No effect in immune parameters was observed in the Probiotic arm. None of the two interventions modified microbial gene richness (alpha diversity). However, intervention as categorical variable was associated with slight but significant effect on Bray-Curtis distance variance (Adonis R2 = 0.02, p = 0.005). Additionally, at month 6, Synbiotic intervention was associated with lower pathway abundances vs Placebo of Assimilatory Sulphate Reduction (8.79·10^-6 (1.25·10^-5) vs. 1.61·10^-5 (2.77·10^-5), p = 0.03) and biosynthesis of methionine (2.3·10^-5 (3.17·10^-5) vs. 4·10^-5 (5.66·10^-5), p = 0.03) and cysteine (1.83·10^-5 (2.56·10^-5) vs. 3.3·10^-5 (4.62·10^-5), p = 0.03). At month 6, probiotic detection in faeces was associated with significant decreases in C Reactive Protein (CRP) vs baseline (11.1(22) vs. 19.2(66), median change= -2.7 (13.2) ug/ml, p = 0.04) and lower IL-6 values (0.58(1.13) vs. 1.17(1.59) ug/ml, p = 0.02) when compared with samples with no detectable probiotic. No detection of the probiotic was associated with higher CD4/CD8 ratio at month 6 vs baseline (0.718(0.57) vs. 0.58(0.4), median change = 0.4(0.2), p = 0.02). After washout, probiotic non-detection was also associated with a significant increase in CD4+ counts (457(153) vs. 416(142), median change = 45(75), counts/ml, p = 0.005) and CD4/CD8 ratio (0.67(0.5) vs 0.59(0.49), median change = 0.04 (0.18), p = 0.02).

Conclusion

A synbiotic intervention with L. plantarum and P. acidilactici was safe and led to small increases in CD4/CD8 ratio and minor reductions in sCD14 of uncertain clinical significance. A probiotic with the same composition was also safe but did not achieve any impact on immune parameters or faecal microbiome composition.

Microbiome-Related Indole and Serotonin Metabolites are Linked to Inflammation and Psychiatric Symptoms in People Living with HIV

Background

People living with HIV (PLHIV) exhibit dysregulation of tryptophan metabolism. Altered gut microbiome composition in PLHIV might be involved. Mechanistic consequences within the 3 major tryptophan metabolism pathways (serotonin, kynurenine, and indoles), and functional consequences for platelet, immune and behavioral functions are unknown. We investigated plasma tryptophan metabolites, gut microbiome composition, and their association with platelet function, inflammation, and psychiatric symptoms.

Methods

This study included 211 PLHIV on long-term antiretroviral treatment (ART). Plasma tryptophan pathway metabolites were measured using time-of-flight mass spectrometry. Bacterial composition was profiled using metagenomic sequencing. Platelet reactivity and serotonin levels were quantified by flowcytometry and ELISA, respectively. Circulating inflammatory markers were determined using ELISA. Symptoms of depression and impulsivity were measured by DASS-42 and BIS-11 self-report questionnaires, respectively.

Results

Plasma serotonin and indole metabolites were associated with gut bacterial composition. Notably, species enriched in PLHIV were associated with 3-methyldioxyindole. Platelet serotonin concentrations were elevated in PLHIV, without effects on platelet reactivity. Plasma serotonin and indole metabolites were positively associated with plasma IL-10 and TNF-α concentrations. Finally, higher tryptophan, serotonin, and indole metabolites were associated with lower depression and anxiety, whereas higher kynurenine metabolites were associated with increased impulsivity.

Conclusion

Our results suggest that gut bacterial composition and dysbiosis in PLHIV on ART contribute to tryptophan metabolism, which may have clinical consequences for immune function and behavior.

Are Nutraceuticals Effective in COVID-19 and Post-COVID Prevention and Treatment?

The beginning of the end or the end of the beginning? After two years mastered by coronavirus disease 19 (COVID-19) pandemic, we are now witnessing a turnaround. The reduction of severe cases and deaths from COVID-19 led to increasing importance of a new disease called post-COVID syndrome. The term post-COVID is used to indicate permanency of symptoms in patients who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Immune, antiviral, antimicrobial therapies, as well as ozone therapy have been used to treat COVID-19 disease. Vaccines have then become available and administered worldwide to prevent the insurgence of the disease. However, the pandemic is not over yet at all given the emergence of new omicron variants. New therapeutic strategies are urgently needed. In this view, great interest was found in nutraceutical products, including vitamins (C, D, and E), minerals (zinc), melatonin, probiotics, flavonoids (quercetin), and curcumin. This review summarizes the role of nutraceuticals in the prevention and/or treatment of COVID-19 disease and post-COVID syndrome.

HIV and cardiovascular disease: the role of inflammation

PURPOSE OF REVIEW

HIV and antiretroviral therapy (ART) use are linked to an increased incidence of atherosclerotic cardiovascular disease (ASCVD). Immune activation persists in ART-treated people with HIV (PWH), and markers of inflammation (i.e. IL-6, C-reactive protein) predict mortality in this population. This review discusses underlying mechanisms that likely contribute to inflammation and the development of ASCVD in PWH.

RECENT FINDINGS

Persistent inflammation contributes to accelerated ASCVD in HIV and several new insights into the underlying immunologic mechanisms of chronic inflammation in PWH have been made (e.g. clonal haematopoiesis, trained immunity, lipidomics). We will also highlight potential pro-inflammatory mechanisms that may differ in vulnerable populations, including women, minorities and children.

SUMMARY

Mechanistic studies into the drivers of chronic inflammation in PWH are ongoing and may aid in tailoring effective therapeutic strategies that can reduce ASCVD risk in this population. Focus should also include factors that lead to persistent disparities in HIV care and comorbidities, including sex as a biological factor and social determinants of health. It remains unclear whether ASCVD progression in HIV is driven by unique mediators (HIV itself, ART, immunodeficiency), or if it is an accelerated version of disease progression seen in the general population.

Probiotics in the Management of Mental and Gastrointestinal Post-COVID Symptomes

Patients with “post-COVID” syndrome manifest with a variety of signs and symptoms that continue/develop after acute COVID-19. Among the most common are gastrointestinal (GI) and mental symptoms. The reason for symptom occurrence lies in the SARS-CoV-2 capability of binding to exact receptors, among other angiotensin converting enzyme 2 (ACE2) receptors in gastrointestinal lining and neuropilin-1 (NRP-1) in the nervous system, which leads to loss of gastrointestinal and blood-brain barriers integrity and function. The data are mounting that SARS-CoV-2 can trigger systemic inflammation and lead to disruption of gut-brain axis (GBA) and the development of disorders of gut brain interaction (DGBIs). Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are the most common DGBIs syndromes. On the other hand, emotional disorders have also been demonstrated as DGBIs. Currently, there are no official recommendations or recommended procedures for the use of probiotics in patients with COVID-19. However, it can be assumed that many doctors, pharmacists, and patients will want to use a probiotic in the treatment of this disease. In such cases, strains with documented activity should be used. There is a constant need to plan and conduct new trials on the role of probiotics and verify their clinical efficacy for counteracting the negative consequences of COVID-19 pandemic. Quality control is another important but often neglected aspect in trials utilizing probiotics in various clinical entities. It determines the safety and efficacy of probiotics, which is of utmost importance in patients with post-acute COVID-19 syndrome.

I've looked at gut from both sides now: Gastrointestinal tract involvement in the pathogenesis of SARS-CoV-2 and HIV/SIV infections

The lumen of the gastrointestinal (GI) tract contains an incredibly diverse and extensive collection of microorganisms that can directly stimulate the immune system. There are significant data to demonstrate that the spatial localization of the microbiome can impact viral disease pathogenesis. Here we discuss recent studies that have investigated causes and consequences of GI tract pathologies in HIV, SIV, and SARS-CoV-2 infections with HIV and SIV initiating GI pathology from the basal side and SARS-CoV-2 from the luminal side. Both these infections result in alterations of the intestinal barrier, leading to microbial translocation, persistent inflammation, and T-cell immune activation. GI tract damage is one of the major contributors to multisystem inflammatory syndrome in SARS-CoV-2-infected individuals and to the incomplete immune restoration in HIV-infected subjects, even in those with robust viral control with antiretroviral therapy. While the causes of GI tract pathologies differ between these virus families, therapeutic interventions to reduce microbial translocation-induced inflammation and improve the integrity of the GI tract may improve the prognoses of infected individuals.

Biological ageing with HIV infection: evaluating the geroscience hypothesis

Although people with HIV are living longer, as they age they remain disproportionately burdened with multimorbidity that is exacerbated in resource-poor settings. The geroscience hypothesis postulates that a discrete set of between five and ten hallmarks of biological ageing drive multimorbidity, but these processes have not been systematically examined in the context of people with HIV. We examine four major hallmarks of ageing (macromolecular damage, senescence, inflammation, and stem-cell dysfunction) as gerodrivers in the context of people with HIV. As a counterbalance, we introduce healthy ageing, physiological reserve, intrinsic capacity, and resilience as promoters of geroprotection that counteract gerodrivers. We discuss emerging geroscience-based diagnostic biomarkers and therapeutic strategies, and provide examples based on recent advances in cellular senescence, and other, non-pharmacological approaches. Finally, we present a conceptual model of biological ageing in the general population and in people with HIV that integrates gerodrivers and geroprotectors as modulators of homoeostatic reserves and organ function over the lifecourse.

Probiotics to HIV-Infected Immunological Nonresponders: Altered Mucosal Immunity and Microbial Diversity Restricted to Ileum

BACKGROUND

HIV-infected immunological nonresponders (INRs) have increased risk of non-AIDS morbidity and compromised gut barrier immunity. Probiotics are widely used to improve health. We assessed the effects of probiotics in INRs with a comprehensive analysis of gut immunity and microbiome in terminal ileum and sigmoid colon.

METHODS

The study involved clinical intervention with five-strain probiotic capsules (1.2 × 1010 CFUs/d) for 8 weeks in 20 INRs with CD4+ T-cell counts <400 cells/µL and plasma HIV RNA <50 copies/mL for more than 3.5 years. Colonoscopy with sampling of gut biopsies from terminal ileum and sigmoid colon and fecal and blood sampling were performed before and after the intervention. Flow cytometry (cytokine production, immune activation, and exhaustion), ELISA (inflammation, microbial translocation, and enterocyte damage), and 16S rRNA sequencing analyses were applied.

RESULTS

In the terminal ileum, increased alpha diversity, increased abundance of Bifidobacterium sp., and decreased frequencies of IL-22+ CD4+ T cells were observed. The increased abundance of Bifidobacterium sp. in the terminal ileum correlated with increased fraction of CD4+ T cells in the same compartment (r = 0.54, P = 0.05) and increased CD4/CD8 ratio in peripheral blood (r = 0.49, P = 0.05). There were no corresponding changes in the sigmoid colon and no changes in fecal microbiome. Probiotic intervention did not affect peripheral blood CD4 count, viral load, or soluble markers of inflammation and microbial translocation.

CONCLUSIONS

Probiotics induced segment-specific changes in the terminal ileum but did not affect systemic CD4 counts in INRs. Further clinical studies are warranted to recommend probiotics to INRs.

Alcohol Use and Abuse Conspires With HIV Infection to Aggravate Intestinal Dysbiosis and Increase Microbial Translocation in People Living With HIV: A Review

The intestinal microbiome is an essential so-called human "organ", vital for the induction of innate immunity, for metabolizing nutrients, and for maintenance of the structural integrity of the intestinal barrier. HIV infection adversely influences the richness and diversity of the intestinal microbiome, resulting in structural and functional impairment of the intestinal barrier and an increased intestinal permeability. Pathogens and metabolites may thus cross the "leaky" intestinal barrier and enter the systemic circulation, which is a significant factor accounting for the persistent underlying chronic inflammatory state present in people living with HIV (PLWH). Additionally, alcohol use and abuse has been found to be prevalent in PLWH and has been strongly associated with the incidence and progression of HIV/AIDS. Recently, converging evidence has indicated that the mechanism underlying this phenomenon is related to intestinal microbiome and barrier function through numerous pathways. Alcohol acts as a "partner" with HIV in disrupting microbiome ecology, and thus impairing of the intestinal barrier. Optimizing the microbiome and restoring the integrity of the intestinal barrier is likely to be an effective adjunctive therapeutic strategy for PLWH. We herein critically review the interplay among HIV, alcohol, and the gut barrier, thus setting the scene with regards to development of effective strategies to counteract the dysregulated gut microbiome and the reduction of microbial translocation and inflammation in PLWH.

Effects of Probiotics on Diarrhea and CD4 Cell Count in People Living With HIV: A Systematic Review and Meta-Analysis

Gastrointestinal probiotics play an important role in maintaining intestinal bacteria homeostasis. They might benefit people with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), which remains a global health challenge. However, there is a controversy regarding the efficacy of probiotics for the treatment of AIDS. This study systematically reviewed the evidence of the effects of existing probiotic interventions on AIDS and sought to provide information on the role of probiotics in the treatment of HIV/AIDS patients. A meta-analysis of studies identified by screening multiple databases was performed using a fixed-effects model in Review Manager 5.2 software. The meta-analysis showed that probiotics could reduce the incidence of AIDS-related diarrhea (RR = 0.60 (95% CI: 0.44–0.82), p = 0.001). The short-term use of probiotics (supplementation duration shorter than 30 days) did not reduce the incidence of diarrhea (RR = 0.76 (95% CI: 0.51–1.14), p = 0.19), while the long-term use of probiotics (supplementation duration longer than 30 days) reduced diarrhea (RR = 0.47 (95% CI: 0.29–0.76), p = 0.002). Probiotics had no effect on CD4 cell counts in HIV/AIDS patients (MD = 21.24 (95% CI: −12.95–55.39), p = 0.22). Our data support that probiotics were associated with an obvious reduction in AIDS-related diarrhea, which indicates the need for additional research on this potential preventive strategy for AIDS.

Lights and Shadows of Microbiota Modulation and Cardiovascular Risk in HIV Patients

Human immunodeficiency virus (HIV) infection is associated with premature aging and the development of aging-related comorbidities, such as cardiovascular disease (CVD). Gut microbiota (GM) disturbance is involved in these comorbidities and there is currently interest in strategies focused on modulating GM composition and/or functionality. Scientific evidence based on well-designed clinical trials is needed to support the use of prebiotics, probiotics, symbiotics, and fecal transplantation (FT) to modify the GM and reduce the incidence of CVD in HIV-infected patients. We reviewed the data obtained from three clinical trials focused on prebiotics, 25 trials using probiotics, six using symbiotics, and four using FT. None of the trials investigated whether these compounds could reduce CVD in HIV patients. The huge variability observed in the type of compound as well as the dose and duration of administration makes it difficult to adopt general recommendations and raise serious questions about their application in clinical practice.

Altered Gut Microbiome under Antiretroviral Therapy: Impact of Efavirenz and Zidovudine

Millions of individuals currently living with HIV globally are receiving antiretroviral therapy (ART) that suppresses viral replication and improves host immune responses. The involvement of gut microbiome during HIV infection has been studied, exposing correlation with immune status and inflammation. However, the direct effect of ART on gut commensals of HIV-infected individuals has been mostly overlooked in microbiome studies. We used 16S rRNA sequencing (Illumina MiSeq) for determining the microbiota composition of stool samples from 16 viremic patients before and one year after ART. We also tested the direct effect of 15 antiretrovirals against four gut microbes, namely, Escherichia coli, Enterococcus faecalis, Bacteroides, and Prevotella to assess their in vitro antibacterial effect. 16S rRNA analysis of fecal samples showed that effective ART for one year does not restore the microbiome diversity in HIV-infected patients. A significant reduction in α-diversity was observed in patients under non-nucleoside reverse transcriptase inhibitors; (NNRTI; 2 NRTI+NNRTI; NRTIs are nucleoside reverse transcriptase inhibitors) as compared to ritonavir-boosted protease inhibitors (PI/r; 2 NRTI+PI/r). Prevotella (P = 0.00001) showed a significantly decreased abundance in patients after ART (n = 16). We also found the direct effect of antivirals on gut microbes, where zidovudine (ZDV) and efavirenz (EFV) showed in vitro antimicrobial activity against Bacteroides fragilis and Prevotella. EFV also inhibited the growth of E. faecalis. Therefore, we observed that ART does not reverse the HIV-induced gut microbiome dysbiosis and might aggravate those microbiota alterations due to the antibacterial effect of certain antiretrovirals (like EFV, ZDV). Our results imply that restructuring the microbiota could be a potential therapeutic target in HIV-1 patients under ART.

Probiotics to manage inflammation in HIV infection

PURPOSE OF REVIEW

To evaluate the current scientific basis for administering probiotics to people living with HIV (PLHIV) to alleviate chronic inflammation and subsequently improve their prognosis.

RECENT FINDINGS

The gut microbiome is a potential contributing factor to low-grade inflammation in HIV infection, and there is a scientific rationale for attempting to attenuate inflammation by administering probiotics. Sixteen reports from clinical studies in antiretroviral therapy (ART)-treated PLHIV assessing inflammation after probiotic intervention have been identified; half of them randomized control trials (RCT). Some of the studies report improvement in some parameters of inflammation, but results are inconsistent. No studies report improvement of CD4 counts. None of the RCTs report improvements in any markers of inflammation when analyzed according to protocol.

SUMMARY

Current scientific evidence does not support the use of probiotics to alleviate inflammation in HIV infection. The potential effect of probiotic intervention in ART-treated PLHIV with high risk for inflammation remains to be investigated.

Prebiotic and probiotic supplementation and the tryptophan-kynurenine pathway: A systematic review and meta analysis

This systematic review aimed to synthesise the results from studies investigating the effects of prebiotics and probiotics on kynurenine pathway metabolism. Thirteen studies were identified for inclusion, comprising 12 probiotic and two prebiotic arms. Participants included healthy individuals and individuals with various clinical conditions. Twelve metabolites were examined across the studies, using a range of biological samples. Across all interventions, 11 reported an effect on ≤ metabolite. Although limited by clinical and methodological heterogeneity, pooled analysis (n = 253) found probiotics to significantly affect serum kynurenine (g = 0.315, CI = 0.070 to 0.560, p = 0.012, 4 studies, I² = 0%) and the kynurenine:tryptophan ratio (g = 0.442, CI = 0.074 to 0.810, p = 0.018, 4 studies, I² = 42 %). Risk of bias across the studies was generally low. The results provide preliminary evidence that probiotics can modulate kynurenine pathway metabolism, with less evidence available regarding prebiotics. Future studies which further consider methodological confounds and sample characteristics are required, to establish intervention efficacy. PROSPERO registration #CRD42019154677.

The Effect of Probiotics, Prebiotics, and Synbiotics on CD4 Counts in HIV-Infected Patients: A Systematic Review and Meta-Analysis

Background

Probiotics as a potential adjuvant therapy may improve the restoration of the intestinal CD4⁺ T-cell population in HIV-infected patients, whereas findings from clinical trials are inconsistent. This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to quantify the effects of probiotic, prebiotic, and synbiotic supplementation on CD4 counts in HIV-infected patients.

Methods

We searched PubMed, Embase, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials for relevant articles published up to March 20, 2020. Two authors independently performed the study selection, data extraction, and risk of bias assessment. Data were pooled by using the random effects model, and weighted mean difference (WMD) was considered the summary effect size. Publication bias was evaluated by a funnel plot and Egger's test.

Results

The search strategy identified 1712 citations. After screening, a total of 16 RCTs with 19 trials were included in the meta-analysis. Pooling of the extracted data indicated no significant difference between the probiotics/prebiotics/synbiotics and placebo groups on CD4 counts (WMD = 3.86, 95% confidence interval (CI) -24.72 to 32.45, P = 0.791). In subgroup analysis, a significant increase in CD4 counts was found in the study with high risk of bias (WMD = 188, 95% CI 108.74 to 227.26, P ≤ 0.001). Egger's test showed no evidence of significant publication bias (P = 0.936).

Conclusions

In summary, the evidence for the efficacy of probiotics, prebiotics, and synbiotics in improving HIV-infected patients' CD4 counts as presented in currently published RCTs is insufficient. Therefore, further comprehensive studies are needed to reveal the exact effect of probiotics, prebiotics, and synbiotics on CD4⁺ cell counts.

Immunomodulatory and Anti-Inflammatory Strategies to Reduce Comorbidity Risk in People with HIV

PURPOSE OF REVIEW

In this review, we will discuss treatment interventions targeting drivers of immune activation and chronic inflammation in PWH.

RECENT FINDINGS

Potential treatment strategies to prevent the progression of comorbidities in PWH have been identified. These studies include, among others, the use of statins to modulate lipid alterations and subsequent innate immune receptor activation, probiotics to restore healthy gut microbiota and reduce microbial translocation, hydroxychloroquine to reduce immune activation by altering Toll-like receptors function and expression, and canakinumab to block the action of a major pro-inflammatory cytokine IL-1β. Although many of the treatment strategies discussed here show promise, due to the complex nature of chronic inflammation and comorbidities in PWH, larger clinical studies are needed to understand and target the prominent drivers and inflammatory cascades underlying these end-organ diseases.

Effect of a Nutritional Intervention on the Intestinal Microbiota of Vertically HIV-Infected Children: The Pediabiota Study

AIMS

The gut microbiota exerts a critical influence in the immune system. The gut microbiota of human virus immunodeficiency (HIV)-infected children remains barely explored. We aimed to characterize the fecal microbiota in vertically HIV-infected children and to explore the effects of its modulation with a symbiotic nutritional intervention.

METHODS

a pilot, double blind, randomized placebo-controlled study including HIV-infected children who were randomized to receive a nutritional supplementation including prebiotics and probiotics or placebo for four weeks. HIV-uninfected siblings were recruited as controls. The V3-V4 region of the 16S rRNA gene was sequenced in fecal samples.

RESULTS

22 HIV-infected children on antiretroviral therapy (ART) and with viral load (VL) <50/mL completed the follow-up period. Mean age was 11.4 ± 3.4 years, eight (32%) were male. Their microbiota showed reduced alpha diversity compared to controls and distinct beta diversity at the genus level (Adonis p = 0.042). Patients showed decreased abundance of commensals Faecalibacterium and an increase in Prevotella, Akkermansia and Escherichia. The nutritional intervention shaped the microbiota towards the control group, without a clear directionality.

CONCLUSIONS

Vertical HIV infection is characterized by changes in gut microbiota structure, distinct at the compositional level from the findings reported in adults. A short nutritional intervention attenuated bacterial dysbiosis, without clear changes at the community level.

SUMMARY

In a group of 24 vertically HIV-infected children, in comparison to 11 uninfected controls, intestinal dysbiosis was observed despite effective ART. Although not fully effective to restore the microbiota, a short intervention with pre/probiotics attenuated bacterial dysbiosis.

The gut microbiome and frailty

The human microbiome is constituted by an extensive network of organisms that lie at the host/environment interface and transduce signals that play vital roles in human health and disease across the lifespan. Frailty is a critical aging-related syndrome marked by diminished physiological reserve and heightened vulnerability to stress, predictive of major adverse clinical outcomes including death. While recent studies suggest the microbiome may impact key pathways critical to frailty pathophysiology, direct evaluation of the microbiome-frailty relationship remains limited. In this article, we review the complex interplay of biological, behavioral, and environmental factors that may influence shifts in gut microbiome composition and function in aging populations and the putative implications of such shifts for progression to frailty. We discuss HIV infection as a key prototype for elucidating the complex pathways via which the microbiome may precipitate frailty. Finally, we review considerations for future research efforts.

Efeitos da suplementação com probióticos em pacientes com o vírus da imunodeficiência humana: revisão sistemática

Objetivo:  É de conhecimento que certos micro-organismos melhoram a função da barreira intestinal, que por sua vez é atingida pela infecção pelo (HIV). Esta revisão teve como objetivo identificar os possíveis efeitos da suplementação com probióticos em pacientes acometidos peloVírus da Imunodeficiência Humana (HIV). Métodos: Foram utilizadas as bases de dados do MEDLINE/PubMed e Lilacs publicados na língua inglesa, no período 2008 a 2018, com os descritores “probiotics” AND “HIV”. Foram incluídos ensaios clínicos randomizados realizados em indivíduos adultos acometidos pelo HIV, que tenham feito uso de probióticos. Foram excluídos artigos não-originais e trabalhos em outro idioma que não a língua inglesa, além de estudos com animais ou in vitro e ainda estudos em gestantes, lactentes e pessoas com idade inferior a 18 anos. Resultados: Do total de 149 artigos encontrados, 10 obedeceram aos critérios de inclusão. As principais cepas utilizadas foram do gênero Lactobacillus e Bifidobacterium. Os principais achados dos estudos estão relacionados à redução da translocação bacteriana e inflamação, aumento do número de células T CD4+ e redução do D-dímero, bem como melhora dos sintomas gastrointestinais. Conclusões: Existem evidências de que a suplementação com probióticos possa ser recomendada na prática clínica como adjuvante da terapia antiretroviral. Entretanto, em decorrência da complexidade do assunto e de os estudos nessa temática serem escassos e heterogêneos, faz-se necessários mais estudos a fim de determinar cepas, tempo de intervenção, dosagens, bem como a efetividade do uso de probióticos por pacientes com HIV.

HIV, Sexual Orientation, and Gut Microbiome Interactions

Recent studies have raised interest in the possibility that dysbiosis of the gut microbiome (i.e., the communities of bacteria residing in the intestine) in HIV-infected patients could contribute to chronic immune activation, and, thus, to elevated mortality and increased risk of inflammation-related clinical diseases (e.g., stroke, cardiovascular disease, cancer, long-bone fractures, and renal dysfunction) found even in those on effective antiretroviral therapy. Yet, to date, a consistent pattern of HIV-associated dysbiosis has not been identified. What is becoming clear, however, is that status as a man who has sex with men (MSM) may profoundly impact the structure of the gut microbiota, and that this factor likely confounded many HIV-related intestinal microbiome studies. However, what factor associated with MSM status drives these gut microbiota-related changes is unclear, and what impact, if any, these changes may have on the health of MSM is unknown. In this review, we outline available data on changes in the structure of the gut microbiome in HIV, based on studies that controlled for MSM status. We then examine what is known regarding the gut microbiota in MSM, and consider possible implications for research and the health of this population. Lastly, we discuss knowledge gaps and needed future studies.

Immune effects of Lactobacillus casei Shirota in treated HIV-infected patients with poor CD4+ T-cell recovery

BACKGROUND

HIV infection leads to depletion of intestinal CD4+ T cells, mucosal barrier dysfunction, increased gut permeability and microbial translocation even among patients on suppressive ART. Previous studies suggest probiotics may help restore intestinal function.

METHODS

In this double-blind, placebo-controlled pilot study, we enrolled HIV-infected patients on suppressive ART with poor CD4+ recovery to address the effect of daily oral use of Lactobacillus casei Shirota (LcS) on CD4+ T-cell count and CD4+/CD8+ ratio at 6 and 12 weeks after treatment initiation; immune activation and intestinal microbiome composition were addressed as secondary outcomes.

RESULTS

From January 2015 to July 2016, 48 patients were randomized (1 : 1) to active intervention or placebo. Groups had comparable demographic and clinical characteristics; only CD4+ T-cell nadir was statistically different between groups. All participants were virologically suppressed under ART. At week 6, the increment in CD4+ T-cell count was 17 cells/μl [interquartile range (IQR) -33 to 74] in the active intervention arm and 4 cells/μl (IQR -43 to 51) in the placebo arm (P = 0.291); at week 12, the change in CD4+ T-cell count was 8 cells//μl (IQR -30 to 70) in the active arm and 10 cells//μl (IQR -50 to 33) among participants allocated to placebo (P = 0.495). Median change in CD4+/CD8+ ratio at week 6 compared with baseline was 0 (IQR -0.04 to 0.05) in the active intervention arm and -0.01 in the placebo arm (IQR -0.06 to 0.03; P = 0.671). At week 12, the change in CD4+/CD8+ ratio was higher in the active product group compared with placebo (respectively 0.07 and 0.01), but this difference failed to reach statistical significance (P = 0.171). We found no significant effects of LcS on immune activation markers, CD4+ and CD8+ subpopulations, sCD14 levels or NK cells at week 12. Finally, we found no statistically significant differences between groups in the change of enteric microbiome at week 12.

CONCLUSION

In this pilot study, we found no statistically significant effect of LcS probiotic on CD4+ T-cell counts, CD4+/CD8+ ratio, immune activation or intestinal microbiome among HIV-infected patients on suppressive ART with poor CD4+ recovery.

The Impact of Human Immunodeficiency Virus Infection on Gut Microbiota α-Diversity: An Individual-level Meta-analysis

BACKGROUND

Whether human immunodeficiency virus (HIV) infection impacts gut microbial α-diversity is controversial. We reanalyzed raw 16S ribosomal RNA (rRNA) gene sequences and metadata from published studies to examine α-diversity measures between HIV-uninfected (HIV-) and HIV-infected (HIV+) individuals.

METHODS

We conducted a systematic review and individual level meta-analysis by searching Embase, Medline, and Scopus for original research studies (inception to 31 December 2017). Included studies reported 16S rRNA gene sequences of fecal samples from HIV+ patients. Raw sequence reads and metadata were obtained from public databases or from study authors. Raw reads were processed through standardized pipelines with use of a high-resolution taxonomic classifier. The χ2 test, paired t tests, and generalized linear mixed models were used to relate α-diversity measures and clinical metadata.

RESULTS

Twenty-two studies were identified with 17 datasets available for analysis, yielding 1032 samples (311 HIV-, 721 HIV+). HIV status was associated with a decrease in measures of α-diversity (P < .001). However, in stratified analysis, HIV status was associated with decreased α-diversity only in women and in men who have sex with women (MSW) but not in men who have sex with men (MSM). In analyses limited to women and MSW, controlling for HIV status, women displayed increased α-diversity compared with MSW.

CONCLUSIONS

Our study suggests that HIV status, sexual risk category, and gender impact gut microbial community α-diversity. Future studies should consider MSM status in gut microbiome analyses.

Effect of Lactobacillus rhamnosus GG Supplementation on Intestinal Inflammation Assessed by PET/MRI Scans and Gut Microbiota Composition in HIV-Infected Individuals

BACKGROUND

Alterations in the gut microbiome have been associated with inflammation and increased cardiovascular risk in HIV-infected individuals. The aim of this study was to investigate the effects of the probiotic strain Lactobacillus rhamnosus GG (LGG) on intestinal inflammation, gut microbiota composition, and systemic markers of microbial translocation and inflammation in HIV-infected individuals.

METHODS

This prospective, clinical interventional trial included 45 individuals [15 combination antiretroviral treatment (cART) naive and 30 cART treated] who ingested LGG twice daily at a dosage of 6 × 109 colony-forming units per capsule for a period of 8 weeks. Intestinal inflammation was assessed using F-2-fluoro-2-deoxy-D-glucose positron emission tomography/magnetic resonance imaging (F-FDG PET/MRI) scans in 15 individuals. Gut microbiota composition (V3-V4 region of the 16s rRNA gene) and markers of microbial translocation and inflammation (lipopolysaccharide, sCD14, sCD163, sCD25, high-sensitive CRP, IL-6, and tumor necrosis factor-alpha) were analyzed at baseline and after intervention.

RESULTS

At baseline, evidence of intestinal inflammation was found in 75% of the participants, with no significant differences between cART-naive and cART-treated individuals. After LGG supplementation, a decrease in intestinal inflammation was detected on PET/MRI (-0.3 mean difference in the combined activity grade score from 6 regions, P = 0.006), along with a reduction of Enterobacteriaceae (P = 0.018) and Erysipelotrichaceae (P = 0.037) in the gut microbiome, with reduced Enterobacteriaceae among individuals with decreased F-FDG uptake on PET/MRI (P = 0.048). No changes were observed for soluble markers of microbial translocation and inflammation.

CONCLUSIONS

A decrease in intestinal inflammation was found in HIV-infected individuals after ingestion of LGG along with a reduced abundance of Enterobacteriaceae, which may explain the local anti-inflammatory effect in the gut.

Effect of daily consumption of extra virgin olive oil on the lipid profile and microbiota of HIV-infected patients over 50 years of age

BACKGROUND

Extra virgin olive oil (EVOO) has shown beneficial effects on the lipid profile and inflammatory parameters in general population. Our goal is to analyze these changes together with those of intestinal microbiota in human immunodeficiency virus (HIV)-infected patients over 50 years of age.

METHODS

Experimental single arm open study. HIV patients over the age of 50 with undetectable viral load were selected. EVOO was distributed among the patients so that each one consumed 50 g daily for 12 weeks. Lipid profile, C-reactive protein (CRP), and intestinal microbiota composition were analyzed at the beginning and at the end of the intervention.

RESULTS

Total cholesterol decreased significantly (5 mg/dL), and a nonsignificant decrease in low-density lipoprotein cholesterol (12 mg/dL), triglycerides (21 mg/dL), and CRP (1.25 mg/dL) was observed. There was a significant increase in alpha diversity after the intervention in men and a decrease in proinflammatory genera such as Dethiosulfovibrionaceae was observed. Differences were also observed in the microbiota of men and women and according to the type of antiretroviral treatment.

CONCLUSION

Sustained consumption of 50 g of EVOO in elderly HIV-infected patients might be associated with an improvement in lipid profile and alfa diversity of intestinal microbiota.

Challenges in the management of HIV infection: update on the role of probiotic supplementation as a possible complementary therapeutic strategy for cART treated people living with HIV/AIDS

Introduction: Recent insights show that gut-mucosal immunity and intestinal microbiota play a key role in the pathogenesis of HIV infection. Alterations in the composition of intestinal flora (dysbiosis) could be associated with an impaired intestinal epithelium barrier activity and an impaired mucosal immunity function, significantly contributing to microbial translocation which is considered a major driver of chronic immune activation. Areas covered: This article provides an overview on the novel trends in probiotic therapy application. A particular emphasis is addressed to the importance of probiotics as a novel strategy to attenuate or prevent gastrointestinal involvement and to improve gut-mucosal immunity in HIV-infected subjects. Therefore, opportunities, limits and methodological criticalities of supplementation with probiotic therapy are considered and analyzed. Expert opinion: Use of probiotics is emerging as a novel strategy to manage dysbiosis and gut-mucosal impairment, to reduce immune activation and to limit a number of non-AIDS-related disorders. However, despite the growing use of probiotic therapy, mechanisms by which oral bacteria intake exhibits its effects are strain-related and disease-specific, hence clinicians need to take these two factors into consideration when suggesting probiotic supplementation to HIV-infected patients.

Gut Microbiome Alterations During HIV/SIV Infection: Implications for HIV Cure

Gut mucosal damage, associated with Human Immunodeficiency Virus-1 (HIV) infection, is characterized by depletion in CD4+ T cells and persistent immune activation as a result of early epithelial barrier disruption and systemic translocation of microbial products. Unique approaches in studying both HIV infection in human patients and Simian Immunodeficiency Virus (SIV) infection in rhesus macaques have provided critical evidence for the pathogenesis and treatment of HIV/AIDS. While there is vast resemblance between SIV and HIV infection, the development of gut dysbiosis attributed to HIV infection in chronically infected patients has not been consistently reported in SIV infection in the non-human primate model of AIDS, raising concerns for the translatability of gut microbiome studies in rhesus macaques. This review outlines our current understanding of gut microbial signatures across various stages of HIV versus SIV infection, with an emphasis on the impact of microbiome-based therapies in restoring gut mucosal immunity as well as their translational potential to supplement current HIV cure efforts.

Microbial translocation revisited: targeting the endotoxic potential of gut microbes in HIV-infected individuals

OBJECTIVE

Translocation of microbial products such as lipopolysaccharides (LPS) from the gut may contribute to chronic inflammation in HIV-infected individuals. Recent studies indicate that differences in degree of acylation of gut-bacterial-derived LPS may explain variable immune effects, with hexa-acylated rather than penta-acylated LPS having proinflammatory capacity. We investigated whether the degree of acylation of gut-derived LPS associates with systemic inflammation, and the potential effect of probiotic intervention.

METHODS

Gut microbiota profiles from a probiotics intervention were investigated and validated in a cohort of HIV-infected individuals commencing antiretroviral therapy. The PiCRUSt software was used to predict overall functional capacity of the microbiota and in-house bioinformatics to distinguish between bacteria producing hexa-acylated and penta-acylated LPS.

RESULTS AND CONCLUSION

HIV-infected individuals with the highest ratio of proinflammatory hexa-acylated LPS to noninflammatory penta-acylated LPS-producing bacteria exhibited increased levels of systemic inflammation (neopterin, P < 0.001) and tryptophan catabolism (kynurenine/tryptophan ratio, P = 0.01), indicating a link between proinflammatory LPS, tryptophan catabolism and inflammation. After probiotics for 8 weeks, there was a decrease in Gram-negative bacteria (P = 0.01), related primarily to a reduction in bacteria producing penta-acylated LPS (P = 0.01), but not hexa-acylated LPS. The reduction in Gram-negative bacteria correlated positively with decreased plasma LPS (r = 0.72), mainly related to a reduction in bacteria producing noninflammatory penta-acylated LPS (r = 0.58). Notably, gut bacteria producing hexa-acylated LPS were outnumbered by penta-acylated LPS with a factor of 25 in HIV-infected individuals. Further studies are warranted to determine whether microbes producing hexa-acylated LPS might be a more relevant trigger of systemic inflammation compared with plasma LPS captured by the existing limulus assay.

Effects of Immunonutrition in Advanced Human Immunodeficiency Virus Disease: A Randomized Placebo-controlled Clinical Trial (Promaltia Study)

BACKGROUND

While nutritional interventions with prebiotics and probiotics seem to exert immunological effects, their clinical implications in human immunodeficiency virus (HIV)-infected subjects initiating antiretroviral therapy (ART) at advanced HIV disease remain unclear.

METHODS

This was a pilot multicenter randomized, placebo-controlled, double-blind study in which 78 HIV-infected, ART-naive subjects with <350 CD4 T cells/μL or AIDS were randomized to either daily PMT25341 (a mixture of synbiotics, omega-3/6 fatty acids and amino acids) or placebo for 48 weeks, each in combination with first-line ART. Primary endpoints were changes in CD4 T-cell counts and CD4/CD8 ratio from baseline to week 48 and safety. Secondary endpoints were changes in markers of T-cell activation, bacterial translocation, inflammation, and α and β microbiota diversity.

RESULTS

Fifty-nine participants completed the follow-up with a mean CD4+ T-cell count of 221 ± 108 cells/μL and mean CD4/CD8 ratio of 0.26 ± 0.19. PMT25341 was well tolerated, without grade 3-4 adverse effects attributable to the intervention. While most of the assessed biomarkers improved during the follow-up in both arms, PMT25341-treated subjects did not experience any significant change, compared to placebo-treated subjects, in mean CD4+ T-cell count change (278 vs 250 cells/μL, P = .474) or CD4/CD8 ratio change (0.30 vs 0.32, P = .854). Similarly, we did not detect differences between treatment arms in secondary endpoints.

CONCLUSIONS

In HIV-infected patients initiating ART at advanced disease, the clear immunological benefits of ART were not enhanced by this nutritional intervention targeting the gut-associated lymphoid tissue and microbiota.

CLINICAL TRIALS REGISTRATION

NCT00870363.

Probiotics in Autoimmune and Inflammatory Disorders

Probiotics have been used to ameliorate gastrointestinal symptoms since ancient times. Over the past 40 years, probiotics have been shown to impact the immune system, both in vivo and in vitro. This interaction is linked to gut microbes, their polysaccharide antigens, and key metabolites produced by these bacteria. At least four metabolic pathways have been implicated in mechanistic studies of probiotics, based on mechanistic studies in animal models. Microbial⁻immune system crosstalk has been linked to: short-chain fatty acid production and signaling, tryptophan metabolism and the activation of aryl hydrocarbon receptors, nucleoside signaling in the gut, and activation of the intestinal histamine-2 receptor. Several randomized controlled trials have now shown that microbial modification by probiotics may improve gastrointestinal symptoms and multiorgan inflammation in rheumatoid arthritis, ulcerative colitis, and multiple sclerosis. Future work will need to carefully assess safety issues, selection of optimal strains and combinations, and attempts to prolong the duration of colonization of beneficial microbes.

Enrichment of gut-derived Fusobacterium is associated with suboptimal immune recovery in HIV-infected individuals

We explored the gut microbiota profile among HIV-infected individuals with diverse immune recovery profiles following long-term suppressive ART and investigated the relationship between the altered bacteria with markers of immune dysfunction. The microbiota profile of rectal swabs from 26 HIV-infected individuals and 20 HIV-uninfected controls were examined. Patients were classified as suboptimal responders, sIR (n = 10, CD4 T-cell <350 cells/ul) and optimal responders, oIR (n = 16, CD4 T-cell >500 cells/ul) after a minimum of 2 years on suppressive ART. Canonical correlation analysis(CCA) and multiple regression modelling were used to explore the association between fecal bacterial taxa abundance and immunological profiles in optimal and suboptimal responders. We found Fusobacterium was significantly enriched among the HIV-infected and the sIR group. CCA results showed that Fusobacterium abundance was negatively correlated with CD4 T-cell counts, but positively correlated with CD4 T-cell activation and CD4 Tregs. Multiple linear regression analysis adjusted for age, baseline CD4 T-cell count, antibiotic exposure and MSM status indicated that higher Fusobacterium relative abundance was independently associated with poorer CD4 T-cell recovery following ART. Enrichment of Fusobacterium was associated with reduced immune recovery and persistent immune dysfunction following ART. Modulating the abundance of this bacterial taxa in the gut may be a viable intervention to improve immune reconstitution in our setting.

Gut microbial diversity in HIV infection post combined antiretroviral therapy: a key target for prevention of cardiovascular disease

PURPOSE OF REVIEW

Although the HIV-infected population is living longer and getting older under current treatment regimens, significant challenges arise for health management as the infection is associated with various premature aging phenotypes, particularly increased incidence of cardiovascular diseases (CVDs). Here we review the current understanding of HIV-related gut dysbiosis in association with CVD and advances in clinical trials aiming to restore gut microbial diversity.

RECENT FINDING

Identification of a unique signature for gut dysbiosis in HIV infection between different cohorts remains challenging. However, low diversity of microbiota combined with the outgrowth of pathogenic bacterial species together with dysregulated metabolic pathways have been linked to compromised gut immunity, bacterial translocation and systemic inflammation, hence higher CVD risk among different cohorts. Data from recent clinical trials aiming to evaluate the tolerability and efficacy of probiotics in treated HIV+ patients are promising and support a significant increase in microbiota diversity and reduction of systemic inflammation. However, the impact of these microbial and immunological corrections on the prevalence of CVD in HIV+ patients remains unclear.

SUMMARY

Positive immunological outcomes following enrichment of the gut microbial diversity have been documented, and further trials are in progress to evaluate the range of patients, with different immunological backgrounds, who might benefit from these treatments.

HIV-associated changes in the enteric microbial community: potential role in loss of homeostasis and development of systemic inflammation

Supplemental Digital Content is available in the text

Purpose of review

Despite HIV therapy advances, average life expectancy in HIV-infected individuals on effective treatment is significantly decreased relative to uninfected persons, largely because of increased incidence of inflammation-related diseases, such as cardiovascular disease and renal dysfunction. The enteric microbial community could potentially cause this inflammation, as HIV-driven destruction of gastrointestinal CD4⁺ T cells may disturb the microbiota–mucosal immune system balance, disrupting the stable gut microbiome and leading to further deleterious host outcomes.

Recent findings

Varied enteric microbiome changes have been reported during HIV infection, but unifying patterns have emerged. Community diversity is decreased, similar to pathologies such as inflammatory bowel disease, obesity, and Clostridium difficile infection. Many taxa frequently enriched in HIV-infected individuals, such as Enterobacteriaceae and Erysipelotrichaceae, have pathogenic potential, whereas depleted taxa, such as Bacteroidaceae and Ruminococcaceae, are more linked with anti-inflammatory properties and maintenance of gut homeostasis. The gut viral community in HIV has been found to contain a greater abundance of pathogenesis-associated Adenoviridae and Anelloviridae. These bacterial and viral changes correlate with increased systemic inflammatory markers, such as serum sCD14, sCD163, and IL-6.

Summary

Enteric microbial community changes may contribute to chronic HIV pathogenesis, but more investigation is necessary, especially in the developing world population with the greatest HIV burden (Video, Supplemental Digital Content 1, which includes the authors’ summary of the importance of the work).

Effect of Probiotic Supplementation on CD4 Cell Count in HIV-Infected Patients: A Systematic Review and Meta-analysis

Progressive decline in CD4 cell counts is associated with human immunodeficiency virus (HIV) disease progression. Loss of CD4 cells might contribute to gut microbiota alteration and bacterial translocation. Probiotics, by inducing epithelial healing, may promote the restoration of the intestinal CD4+ T-cell population. The aim of this meta-analysis was to systematically review all randomized controlled trials (RCTs) of probiotic/prebiotic/synbiotic supplementation on CD4 cell counts in HIV-infected patients. A systematic search of RCTs was conducted through PubMed, Scopus, and Google Scholar databases up to August 2015. Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). Eleven studies with 14 treatment arms met the inclusion criteria. Pooled analysis showed no significant reduction in CD4 counts (-7.5 mg/l, p = .7) in intervention-treated individuals. Subgroup analysis on potential influencing factors highlighted sex, country of origin, study duration, and the type of intervention as having significant effects on CD4 cell counts. As a whole, the results of this meta-analysis suggested that supplementation with probiotic may not change CD4 counts. However, a significant increase in CD4 counts was seen in females and following synbiotics as opposed to treatment with pro- or prebiotics alone.

Probiotic supplementation promotes a reduction in T-cell activation, an increase in Th17 frequencies, and a recovery of intestinal epithelium integrity and mitochondrial morphology in ART-treated HIV-1-positive patients

INTRODUCTION

HIV infection is characterized by a persistent immune activation associated to a compromised gut barrier immunity and alterations in the profile of the fecal flora linked with the progression of inflammatory symptoms. The effects of high concentration multistrain probiotic (Vivomixx®, Viale del Policlinico 155, Rome, Italy in EU; Visbiome®, Dupont, Madison, Wisconsin in USA) on several aspects of intestinal immunity in ART-experienced HIV-1 patients was evaluated.

METHODS

A sub-study of a longitudinal pilot study was performed in HIV-1 patients who received the probiotic supplement twice a day for 6 months (T6). T-cell activation and CD4+ and CD8+ T-cell subsets expressing IFNγ (Th1, Tc1) or IL-17A (Th17, Tc17) were stained by cytoflorimetric analysis. Histological and immunohistochemical analyses were performed on intestinal biopsies while enterocytes apoptosis index was determined by TUNEL assay.

RESULTS

A reduction in the frequencies of CD4+ and CD8+ T-cell subsets, expressing CD38+ , HLA-DR+ , or both, and an increase in the percentage of Th17 cell subsets, especially those with central or effector memory phenotype, was recorded in the peripheral blood and in gut-associated lymphoid tissue (GALT) after probiotic intervention. Conversely, Tc1 and Tc17 levels remained substantially unchanged at T6, while Th1 cell subsets increase in the GALT. Probiotic supplementation was also associated to a recovery of the integrity of the gut epithelial barrier, a reduction of both intraepithelial lymphocytes density and enterocyte apoptosis and, an improvement of mitochondrial morphology sustained in part by a modulation of heat shock protein 60.

CONCLUSIONS

These findings highlight the potential beneficial effects of probiotic supplementation for the reconstitution of physical and immunological integrity of the mucosal intestinal barrier in ART-treated HIV-1-positive patients.

The effects of prebiotics on microbial dysbiosis, butyrate production and immunity in HIV-infected subjects

Altered interactions between the gut mucosa and bacteria during HIV infection seem to contribute to chronic immune dysfunction. A deeper understanding of how nutritional interventions could ameliorate gut dysbiosis is needed. Forty-four subjects, including 12 HIV⁺ viremic untreated (VU) patients, 23 antiretroviral therapy-treated (ART⁺) virally suppressed patients (15 immunological responders and 8 non-responders) and 9 HIV^- controls (HIV^-), were blindly randomized to receive either prebiotics (scGOS/lcFOS/glutamine) or placebo (34/10) over 6 weeks in this pilot study. We assessed fecal microbiota composition using deep 16S rRNA gene sequencing and several immunological and genetic markers involved in HIV immunopathogenesis. The short dietary supplementation attenuated HIV-associated dysbiosis, which was most apparent in VU individuals but less so in ART⁺ subjects, whose gut microbiota was found more resilient. This compositional shift was not observed in the placebo arm. Significantly, declines in indirect markers of bacterial translocation and T-cell activation, improvement of thymic output, and changes in butyrate production were observed. Increases in the abundance of Faecalibacterium and Lachnospira strongly correlated with moderate but significant increases of butyrate production and amelioration of the inflammatory biomarkers soluble CD14 and high-sensitivity C-reactive protein, especially among VU. Hence, the bacterial butyrate synthesis pathway holds promise as a viable target for interventions.

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.

Plasma IP-10 Is Increased in Immunological NonResponders and Associated With Activated Regulatory T Cells and Persisting Low CD4 Counts

OBJECTIVE

To explore immune mechanisms and identify biomarkers associated with an inadequate immune recovery in patients with HIV with efficient antiretroviral therapy.

DESIGN

A cross-sectional study of 67 HIV-infected patients on antiretroviral therapy for ≥24 months with HIV RNA ≤20 copies per milliliter; 41 were defined as immunological nonresponders (INR) (CD4 < 400 cells per microliter) and 26 as immunological responders (CD4 > 600 cells per microliter). CD4 counts were also registered 2 years after inclusion.

METHODS

Cytokines, soluble markers of microbial translocation, and tryptophan catabolites were measured in plasma by multiplex assay, ELISA, or mass spectrometry. T-cell activation, differentiation, and regulatory T cells (Tregs) were analyzed by flow cytometry in 2 subgroups with comparable nadir CD4 counts.

RESULTS

Plasma interferon-inducible protein-10 (IP-10) levels were higher (P < 0.05), the T cells were more activated (CD38HLA-DR) (P < 0.05), the naive/effector memory T-cell ratio was lower (P < 0.01) and the proportion of resting Tregs (CD4CD45RAFoxP3) was reduced (P < 0.001) in INR patients compared with immunological responders. INR patients with CD4 counts ≤300 cells per microliter also demonstrated a higher fraction of activated Tregs (aTreg) (CD4CD147CD25) (P < 0.05). In the INR group, the aTreg percentages correlated with plasma IP-10 levels and inversely with CD4 counts (both P < 0.01). IP-10 levels (P < 0.05) and kynurenine/tryptophan ratio (P < 0.01) were negatively associated with the CD4 count 2 years after inclusion.

CONCLUSION

Patients with HIV with inadequate CD4 responses had higher levels of IP-10, more activated and differentiated T-cell phenotypes, as well as aTreg, compared with patients with satisfactory CD4 gain. High IP-10 levels were also associated with lower CD4 counts after 2 years.

Gut Mucosal Barrier Dysfunction, Microbial Dysbiosis, and Their Role in HIV-1 Disease Progression

Distinct pathological events occur within the gastrointestinal (GI) tract of Asian macaques with progressive simian immunodeficiency virus (SIV) infection and humans with human immunodeficiency virus type 1 (HIV-1) infection that are critical in shaping disease course. These events include depletion and functional alteration of GI-resident CD4(+) T cells, loss of antigen-presenting cells, loss of innate lymphocytes, and possible alterations to the composition of the gut microbiota. These contribute to structural damage to the GI tract and systemic translocation of GI tract microbial products. These translocated microbial products directly stimulate the immune system, and there is now overwhelming evidence that this drives chronic immune activation in HIV-1 and SIV infection. While combined antiretroviral therapy (cART) in HIV-1-infected subjects generally allows for immune reconstitution in peripheral blood, reconstitution of the GI tract occurs at a much slower pace, and both immunological and structural abnormalities persist in the GI tract. Importantly, studies of large cohorts of individuals have linked suboptimal GI reconstitution to residual inflammation and heightened morbidities in HIV-1-infected cART recipients. As a result, current era treatments aimed at augmenting restoration of the GI tract hold promise in returning cART recipients to full health.

Impact of Probiotic Administration on Serum C-Reactive Protein Concentrations: Systematic Review and Meta-Analysis of Randomized Control Trials

We conducted this systematic review and meta-analysis of prospective studies to determine the effect of probiotic administration on serum C-reactive protein (CRP) concentrations. We searched PubMed-Medline, Web of Science, the Cochrane, and Google Scholar databases (until May 2016) to identify prospective studies evaluating the impact of probiotic administration on CRP. We used a random effects models and generic inverse variance methods to synthesize quantitative data, followed by a leave-one-out method for sensitivity analysis. The systematic review registration number was: CRD42016039457. From a total of 425 entries identified via searches, 20 studies were included in the final analysis. The meta-analysis indicated a significant reduction in serum CRP following probiotic administration with a weighted mean difference (WMD) of -1.35 mg/L, (95% confidence interval (CI) -2.15 to -0.55, I² 65.1%). The WMDs for interleukin 10 (IL10) was -1.65 pg/dL, (95% CI -3.45 to 0.14, I² 3.1%), and -0.45 pg/mL, (95% CI -1.38 to 0.48, I² 10.2%) for tumor necrosis factor alpha (TNF-α). These findings were robust in sensitivity analyses. This meta-analysis suggests that probiotic administration may significantly reduce serum CRP while having no significant effect on serum IL10 and TNF-α.

Impact of probiotic Saccharomyces boulardii on the gut microbiome composition in HIV-treated patients: A double-blind, randomised, placebo-controlled trial

Dysbalance in gut microbiota has been linked to increased microbial translocation, leading to chronic inflammation in HIV-patients, even under effective HAART. Moreover, microbial translocation is associated with insufficient reconstitution of CD4+T cells, and contributes to the pathogenesis of immunologic non-response. In a double-blind, randomised, placebo-controlled trial, we recently showed that, compared to placebo, 12 weeks treatment with probiotic Saccharomyces boulardii significantly reduced plasma levels of bacterial translocation (Lipopolysaccharide-binding protein or LBP) and systemic inflammation (IL-6) in 44 HIV virologically suppressed patients, half of whom (n = 22) had immunologic non-response to antiretroviral therapy (<270 CD4+Tcells/μL despite long-term suppressed viral load). The aim of the present study was to investigate if this beneficial effect of the probiotic Saccharomyces boulardii is due to modified gut microbiome composition, with a decrease of some species associated with higher systemic levels of microbial translocation and inflammation. In this study, we used 16S rDNA gene amplification and parallel sequencing to analyze the probiotic impact on the composition of the gut microbiome (faecal samples) in these 44 patients randomized to receive oral supplementation with probiotic or placebo for 12 weeks. Compared to the placebo group, in individuals treated with probiotic we observed lower concentrations of some gut species, such as those of the Clostridiaceae family, which were correlated with systemic levels of bacterial translocation and inflammation markers. In a sub-study of these patients, we observed significantly higher parameters of microbial translocation (LBP, soluble CD14) and systemic inflammation in immunologic non-responders than in immunologic responders, which was correlated with a relative abundance of specific gut bacterial groups (Lachnospiraceae genus and Proteobacteria). Thus, in this work, we propose a new therapeutic strategy using the probiotic yeast S. boulardii to modify gut microbiome composition. Identifying pro-inflammatory species in the gut microbiome could also be a useful new marker of poor immune response and a new therapeutic target.