Vitamin D and Phenylbutyrate Supplementation Does Not Modulate Gut Derived Immune Activation in HIV-1

Mechanisms of HIV-immunologic non-responses and research trends based on gut microbiota

With the increasing number of people with HIV (PWH) and the use of antiretroviral treatment (ART) for PWH, HIV has gradually become a chronic infectious disease. However, some infected individuals develop issues with immunologic non-responses (INRs) after receiving ART, which can lead to secondary infections and seriously affect the life expectancy and quality of life of PWH. Disruption of the gut microbiota is an important factor in immune activation and inflammation in HIV/AIDS, thus stabilizing the gut microbiota to reduce immune activation and inflammation and promoting immune reconstitution may become a direction for the treatment of HIV/AIDS. This paper, based on extensive literature review, summarizes the definition, mechanisms, and solutions for INRs, starting from the perspective of gut microbiota.

Intestinal Microbiota and Aging in People with HIV-What We Know and What We Don't

PURPOSE OF REVIEW

People with HIV (PWH) experience premature aging and an elevated risk of age-related comorbidities, even with viral suppression through antiretroviral therapy (ART). We examine gastrointestinal disruptions, specifically impaired intestinal barrier integrity and microbial dysbiosis, as contributors to these comorbidities.

RECENT FINDINGS

HIV infection compromises the intestinal epithelial barrier, increasing permeability and microbial translocation, which trigger inflammation and cellular stress. ART does not fully restore gut barrier integrity, leading to persistent inflammation and cellular stress. Additionally, HIV-associated microbial dysbiosis favors pro-inflammatory bacteria, intensifying inflammation and tissue damage, which may contribute to premature aging in PWH. Understanding the interactions between intestinal microbiota, chronic inflammation, cellular stress, and aging is essential to developing therapies aimed at reducing inflammation and slowing age-related diseases in PWH. In this review, we discuss critical knowledge gaps and highlight the therapeutic potential of microbiota-targeted interventions to mitigate inflammation and delay age-associated pathologies in PWH.

Therapeutic microbiome modulation: new frontiers in HIV treatment

PURPOSE OF REVIEW

Dysbiosis may be a key driver of systemic inflammation, which increases the risk of non-AIDS events in people living with HIV (PLWH). Modulation of the microbiome to reverse this dysbiosis may be a novel approach to decrease inflammation and therefore morbidity and mortality in PLWH.

RECENT FINDINGS

Fecal microbiota transplantation (FMT), probiotics, prebiotics, synbiotics, postbiotics, and dietary modifications have the potential to modulate the microbiome. These interventions have been well tolerated in clinical trials to date. However, these interventions have not resulted in consistent or lasting changes to the microbiome or consistent changes in biomarkers of intestinal permeability, microbial translocation, inflammation, immune activation, or CD4 + T cell counts. Sustained engraftment may require prebiotics and/or dietary modifications added to either probiotics or FMT.

SUMMARY

Adequately powered randomized controlled trials are needed to elucidate whether microbiome modulation can be achieved and impact systemic inflammation in PLWH.

Origami of KR-12 Designed Antimicrobial Peptides and Their Potential Applications

This review describes the discovery, structure, activity, engineered constructs, and applications of KR-12, the smallest antibacterial peptide of human cathelicidin LL-37, the production of which can be induced under sunlight or by vitamin D. It is a moonlighting peptide that shows both antimicrobial and immune-regulatory effects. Compared to LL-37, KR-12 is extremely appealing due to its small size, lack of toxicity, and narrow-spectrum antimicrobial activity. Consequently, various KR-12 peptides have been engineered to tune peptide activity and stability via amino acid substitution, end capping, hybridization, conjugation, sidechain stapling, and backbone macrocyclization. We also mention recently discovered peptides KR-8 and RIK-10 that are shorter than KR-12. Nano-formulation provides an avenue to targeted delivery, controlled release, and increased bioavailability. In addition, KR-12 has been covalently immobilized on biomaterials/medical implants to prevent biofilm formation. These constructs with enhanced potency and stability are demonstrated to eradicate drug-resistant pathogens, disrupt preformed biofilms, neutralize endotoxins, and regulate host immune responses. Also highlighted are the safety and efficacy of these peptides in various topical and systemic animal models. Finaly, we summarize the achievements and discuss future developments of KR-12 peptides as cosmetic preservatives, novel antibiotics, anti-inflammatory peptides, and microbiota-restoring agents.

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.

A Scoping Review Evaluating the Current State of Gut Microbiota Research in Africa

The gut microbiota has emerged as a key human health and disease determinant. However, there is a significant knowledge gap regarding the composition, diversity, and function of the gut microbiota, specifically in the African population. This scoping review aims to examine the existing literature on gut microbiota research conducted in Africa, providing an overview of the current knowledge and identifying research gaps. A comprehensive search strategy was employed to identify relevant studies. Databases including MEDLINE (PubMed), African Index Medicus (AIM), CINAHL (EBSCOhost), Science Citation index (Web of Science), Embase (Ovid), Scopus (Elsevier), WHO International Clinical Trials Registry Platform (ICTRP), and Google Scholar were searched for relevant articles. Studies investigating the gut microbiota in African populations of all age groups were included. The initial screening included a total of 2136 articles, of which 154 were included in this scoping review. The current scoping review revealed a limited number of studies investigating diseases of public health significance in relation to the gut microbiota. Among these studies, HIV (14.3%), colorectal cancer (5.2%), and diabetes mellitus (3.9%) received the most attention. The top five countries that contributed to gut microbiota research were South Africa (16.2%), Malawi (10.4%), Egypt (9.7%), Kenya (7.1%), and Nigeria (6.5%). The high number (n = 66) of studies that did not study any specific disease in relation to the gut microbiota remains a gap that needs to be filled. This scoping review brings attention to the prevalent utilization of observational study types (38.3%) in the studies analysed and emphasizes the importance of conducting more experimental studies. Furthermore, the findings reflect the need for more disease-focused, comprehensive, and population-specific gut microbiota studies across diverse African regions and ethnic groups to better understand the factors shaping gut microbiota composition and its implications for health and disease. Such knowledge has the potential to inform targeted interventions and personalized approaches for improving health outcomes in African populations.

A Systematic Review and Meta-Analysis of Randomized Controlled Trials of the Effects of Vitamin D Supplementation on Children and Young Adults with HIV Infection

BACKGROUND

Children and young adults with HIV infection may exhibit vitamin D deficiency, which is harmful to bone health as well as the endocrine and immune systems.

OBJECTIVES

This study sought to investigate the effect of vitamin D supplementation on children and young adults with HIV infection.

METHODS

The PubMed, Embase, and Cochrane databases were searched. Randomized controlled trials that have evaluated the effects of vitamin D supplementation (ergocalciferol or cholecalciferol) at any dose or for any duration in children and young adults with HIV infection, aged 0-25 y, were included. A random-effects model was used, and the standardized mean difference (SMD) and 95% CI were calculated.

RESULTS

Ten trials, with 21 publications and 966 participants (mean age: 17.9 y), were included in the meta-analysis. The supplementation dose and the duration of the studies included ranged from 400 to 7000 IU/d and from 6 to 24 mo, respectively. Vitamin D supplementation was associated with a significantly higher serum 25(OH)D concentration at 12 mo (SMD: 1.14; 95% CI: 0.64, 1.65; P < 0.00001) compared with a placebo. No significant difference was observed in spine BMD (SMD: -0.09; 95% CI: -0.47, 0.3; P = 0.65) at 12 mo between these 2 groups. However, participants who received higher doses (1600-4000 IU/d) had significantly higher total BMD (SMD: 0.23; 95% CI: 0.02, 0.44; P = 0.03) and nonsignificantly higher spine BMD (SMD: 0.3; 95% CI: -0.02, 0.61; P = 0.07) at 12 mo compared with those who received standard doses (400-800 IU/d).

CONCLUSIONS

Vitamin D supplementation in children and young adults with HIV infection increases the serum 25(OH)D concentration. A relatively high daily dose of vitamin D (1600-4000 IU) improves total BMD at 12 mo and results in sufficient 25(OH)D concentrations.

The Association between Vitamin D and Gut Microbiota: A Systematic Review of Human Studies

Recent evidence has shown a number of extra-skeletal functions of Vitamin D (VD), primarily involving the immune system. One of these functions is mediated by the modulation of gut microbiota, whose alterations are linked to many diseases. Our purpose is to contribute to the understanding of existing evidence on the association between VD and gastrointestinal microbiota alterations. A systematic review of studies with human subjects has been conducted up to January 2021. We included publications reporting the association between gut microbiota and VD, including VD supplementation, dietary VD intake and/or level of 25(OH)D. We identified 25 studies: 14 were interventional and 11, observational. VD supplementation was found to be associated with a significant change in microbiome composition, in particular of Firmicutes, Actinobacteria and Bacteroidetes phyla. Furthermore, Firmicutes were found to be correlated with serum VD. Concerning alpha and beta diversity, a high nutritional intake of VD seems to induce a shift in bacterial composition and/or affects the species’ richness. Veillonellaceae and Oscillospiraceae families, in the Firmicutes phylum, more frequently decreased with both increasing levels of 25(OH)D and vitamin D supplementation. We found evidence of an association, even though the studies are substantially heterogeneous and have some limitations, resulting sometimes in conflicting results. To further understand the role of VD on the modulation of the gastrointestinal microbiota, future research should be geared toward well-designed animal-based studies or larger randomized controlled trials (RCTs).

Adjunct Therapy for CD4+ T-Cell Recovery, Inflammation and Immune Activation in People Living With HIV: A Systematic Review and Meta-Analysis

Background: HIV infection results in immune homeostasis perturbations, which is characterized by CD4⁺ T-cell depletion, immune activation, and inflammation. Effective antiretroviral therapy (ART) does not fully restore immunologic and clinical health in people living with HIV (PLWH). Various drugs have been used to improve their immune status and CD4⁺ T-cell counts, but no measures have been tested effective. Here we conduct a systematic review and meta-analysis of existing clinical studies on improving CD4⁺ T-cell count while decreasing inflammation and immune activation.

Methods: We retrieved possible relevant publications from a total of five electronic databases and selected eligible studies, which dealt with outcomes of medical therapy for CD4⁺ T-cell count recovery, inflammation, and immune activation with or without ART. We paid particular attention to immunologic non-responders with a favorable treatment regimen.

Results: Thirty-three articles were included in the systematic review and meta-analysis. However, there were no safe and effective medications specific for improving CD4⁺ T-cell reconstitution. The immunological benefits or adverse events mainly depend on the safety, dosage, and duration of the candidate medication use, as well as whether it is combined with ART.

Conclusion: Under the “safe, combined, adequate and long (SCAL)” principles, alternative approaches are needed to accelerate the recovery of CD4⁺ T-cells, and to prevent adverse long-term outcomes in PLWH with standard ART treatment.

Can diet modulate trimethylamine N-oxide (TMAO) production? What do we know so far?

BACKGROUND

Trimethylamine N-oxide (TMAO) is a metabolite that has attracted attention due to its positive association with several chronic non-communicable diseases such as insulin resistance, atherosclerotic plaque formation, diabetes, cancer, heart failure, hypertension, chronic kidney disease, liver steatosis, cardiac fibrosis, endothelial injury, neural degeneration and Alzheimer's disease. TMAO production results from the fermentation by the gut microbiota of dietary nutrients such as choline and carnitine, which are transformed to trimethylamine (TMA) and converted into TMAO in the liver by flavin-containing monooxygenase 1 and 3 (FMO1 and FMO3). Considering that TMAO is involved in the development of many chronic diseases, strategies have been found to enhance a healthy gut microbiota. In this context, some studies have shown that nutrients and bioactive compounds from food can modulate the gut microbiota and possibly reduce TMAO production.

OBJECTIVE

This review has as main objective to discuss the studies that demonstrated the effects of food on the reduction of this harmful metabolite.

METHODS

All relevant articles until November 2020 were included. The articles were searched in Medline through PubMed.

RESULTS

Both the food is eaten acutely and chronically, by altering the nature of the gut microbiota, influencing colonic TMA production. Furthermore, hepatic production of TMAO by the flavin monooxygenases in the liver may also be influenced by phenolic compounds present in foods.

CONCLUSION

The evidence presented in this review shows that TMAO levels can be reduced by some bioactive compounds. However, it is crucial to notice that there is significant variation among the studies. Further clinical studies should be conducted to evaluate these dietary components' effectiveness, dose, and intervention time on TMAO levels and its precursors.

Immunomodulatory Role of the Antimicrobial LL-37 Peptide in Autoimmune Diseases and Viral Infections

Antimicrobial peptides (AMPs) are produced by neutrophils, monocytes, and macrophages, as well as epithelial cells, and are an essential component of innate immunity system against infection, including several viral infections. AMPs, in particular the cathelicidin LL-37, also exert numerous immunomodulatory activities by inducing cytokine production and attracting and regulating the activity of immune cells. AMPs are scarcely expressed in normal skin, but their expression increases when skin is injured by external factors, such as trauma, inflammation, or infection. LL-37 complexed to self-DNA acts as autoantigen in psoriasis and lupus erythematosus (LE), where it also induces production of interferon by plasmocytoid dendritic cells and thus initiates a cascade of autocrine and paracrine processes, leading to a disease state. In these disorders, epidermal keratinocytes express high amounts of AMPs, which can lead to uncontrolled inflammation. Similarly, LL-37 had several favorable and unfavorable roles in virus replication and disease pathogenesis. Targeting the antiviral and immunomodulatory functions of LL-37 opens a new approach to limit virus dissemination and the progression of disease.

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.