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

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.

HIV and comorbidities - the importance of gut inflammation and the kynurenine pathway

PURPOSE OF REVIEW

The purpose of this article is to review alterations in microbiota composition, diversity, and functional features in the context of chronic inflammation and comorbidities associated with HIV infection.

RECENT FINDINGS

The gut microbiome is an important mediator of host immunity, and disruption of gut homeostasis can contribute to both systemic inflammation and immune activation. Ageing and HIV share features of intestinal damage, microbial translocation and alterations in bacterial composition that contribute to a proinflammatory state and development of age-related comorbidities. One such inflammatory pathway reviewed is the nicotinamide adenine dinucleotide (NAD+) producing kynurenine pathway (KP). Kynurenine metabolites regulate many biological processes including host-microbiome communication, immunity and oxidative stress and the KP in turn is influenced by the microbiome environment. Age-associated decline in NAD+ is implicated as a driving factor in many age-associated diseases, including those seen in people with HIV (PWH). Recent studies have shown that KP can influence metabolic changes in PWH, including increased abdominal adiposity and cardiovascular disease. Furthermore, KP activity increases with age in the general population, but it is elevated in PWH at all ages compared to age-matched controls. Host or microbiome-mediated targeting of this pathway has merits to increase healthy longevity and has potential therapeutic applications in PWH.

SUMMARY

As a growing proportion of PWH age, many face increased risks of developing age-related comorbidities. Chronic inflammation, a pillar of geroscience, the science of ageing and of age-related disease, is influenced by the gut microbiome and its metabolites. Combined, these contribute to a systemic inflammatory signature. Advances in geroscience-based approaches and therapeutics offer a novel paradigm for addressing age-related diseases and chronic inflammation in HIV infection. Whether targeted inhibition of KP activity alleviates pathological conditions or promotes successful ageing in PWH remains to be determined.

Enteropathy and gut dysbiosis as obstacles to achieve immune recovery in undetectable people with HIV: a clinical view of evidence, successes, and projections

Immune performance following antiretroviral therapy initiation varies among patients. Despite achieving viral undetectability, a subgroup of patients fails to restore CD4+ T-cell counts during follow-up, which exposes them to non-AIDS defining comorbidities and increased mortality. Unfortunately, its mechanisms are incompletely understood, and no specific treatment is available. In this review, we address some of the pathophysiological aspects of the poor immune response from a translational perspective, with emphasis in the interaction between gut microbiome, intestinal epithelial dysfunction, and immune system, and we also discuss some studies attempting to improve immune performance by intervening in this vicious cycle.

Effect of Probiotics on the Frequency of CD4+ T-Cells in HIV-Infected Children and Adolescents: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Depletion of CD4+ T-cells in the gut-associated lymphoid tissue is the hallmark of HIV infection, with only partial restoration by potent antiretroviral therapy (ART). Gut dysbiosis, together with disruption of mucosal integrity contributes to chronic immune activation that further exacerbates the disease. Data from randomized controlled trials in pediatric HIV patients have indicated potential of probiotics in complementing routine ART in managing HIV-associated gastrointestinal complications. We have systematically extracted data from these trials and performed meta-analysis to quantify the effect of probiotics on CD4+ T-cell counts and any adverse events associated with their supplementation.

METHODS

A systematic search through multiple databases yielded three studies that were pooled using fixed-effect model. Risk of bias assessment was done by the Cochrane risk of bias tool and publication bias was assessed by Egger's test.

RESULTS

Included studies had moderate risk of bias and Egger's statistics revealed no publication bias (p > 0.05). Pooled analysis showed significant improvement in CD4+ T-cell counts, with mean difference, 123.92 (95% CI: 104.36-143.48), p < 0.0001, no heterogeneity (I2=0) among the included trials. Subgroup analysis also depicted improvement in CD4+ T-cell counts irrespective of treatment duration, in both ART naïve and treated patients. No adverse effects with probiotic consumption were reported.

CONCLUSIONS

Probiotics supplementation led to an improvement in CD4+ T-cell counts among HIV-infected children with no observed adverse effects. Despite the inherent limitations of included studies, our systematic review would justify more well-designed, large-scale trials in children, which may guide pediatricians on whether to incorporate probiotics as an adjunct therapy to routine ART.