Alcohol Use Is Associated With Intestinal Dysbiosis and Dysfunctional CD8+ T-Cell Phenotypes in Persons With Human Immunodeficiency Virus

Gut-liver axis: Recent concepts in pathophysiology in alcohol-associated liver disease

The growing recognition of the role of the gut microbiome's impact on alcohol-associated diseases, especially in alcohol-associated liver disease, emphasizes the need to understand molecular mechanisms involved in governing organ-organ communication to identify novel avenues to combat alcohol-associated diseases. The gut-liver axis refers to the bidirectional communication and interaction between the gut and the liver. Intestinal microbiota plays a pivotal role in maintaining homeostasis within the gut-liver axis, and this axis plays a significant role in alcohol-associated liver disease. The intricate communication between intestine and liver involves communication between multiple cellular components in each organ that enable them to carry out their physiological functions. In this review, we focus on novel approaches to understanding how chronic alcohol exposure impacts the microbiome and individual cells within the liver and intestine, as well as the impact of ethanol on the molecular machinery required for intraorgan and interorgan communication.

Gut Microbiota Richness and Diversity Track With T Cell Aging in Healthy Adults

BACKGROUND

This study examined how gut microbiota diversity and richness relate to T cell aging among 96 healthy adults of all ages. It also explored whether these links differed throughout the lifespan.

METHODS

Peripheral blood was obtained from 96 study participants (N = 96, aged 21-72) to assess mRNA markers of T cell aging (p16ink4a, p14ARF, B3gat1, Klrg1) and DNA methylation. T cell aging mRNA markers were combined into an aging index, and the Horvath epigenetic clock algorithm was used to calculate epigenetic age based on DNA methylation status of over 500 loci. Participants also collected a stool sample from which the V4 region of the 16S rRNA gene was sequenced to derive the Shannon and Simpson diversity indices, and the total count of observed operational taxonomic units (richness). Models controlled for BMI, comorbidities, sex, dietary quality, smoking status, physical activity, and sleep quality.

RESULTS

Lower microbiota richness was associated with higher T cell age based on mRNA markers, but when probing the region of significance, this relationship was only significant among adults 45 years and older (p = .03). Lower Shannon diversity (p = .05) and richness (p = .07) marginally correlated with higher epigenetic age (ie, greater T cell DNA methylation).

CONCLUSIONS

Gut microbiota complexity may correspond with the rate of T cell aging, especially in mid-to-late life. These results suggest an interplay between the gut microbiome and immunological aging that warrants further experimental work.

Effects of alcohol on the composition and metabolism of the intestinal microbiota among people with HIV: a cross-sectional study

OBJECTIVES

Alcohol consumption is not uncommon among people with HIV (PWH) and may exacerbate HIV-induced intestinal damage, and further lead to dysbiosis and increased intestinal permeability. This study aimed to determine the changes in the faecal microbiota and its association with alcohol consumption in HIV-infected patients.

METHODS

A cross-sectional survey was conducted between November 2021 and May 2022, and 93 participants were recruited. To investigate the alterations of alcohol misuse on fecal microbiology in HIV-infected individuals, we performed 16s rDNA gene sequencing on fecal samples from the low to moderate drinking (n=21) and non-drinking (n=72) groups.

RESULTS

Comparison between groups using alpha and beta diversity showed that the diversity of stool microbiota in the low to moderate drinkinge group did not differ from that of the non-drinking group (all P>0.05). The Linear discriminant Analysis effect size (LEfSe) algorithm was to determine the bacterial taxa associated with alcohol consumption, and the results showed altered fecal bacterial composition in HIV-infected patients who consumed alcohol, with Coprobacillus, Pseudobutyrivibrio and Peptostreptococcaceae enriched, and Pasteurellaceae and Xanthomonadaceae were depleted. In addition, by using the Kyoto Encyclopedia of Genes and Genomes (KEGG) functional microbiome features were also found to be altered in the low to moderate drinking group, showing a reduction in metabolic pathways (P=0.036) and cardiovascular disease pathway (P=0.006).

CONCLUSION

Low to moderate drinking will change the composition, metabolism and cardiovascular disease pathway of the gut microbiota of HIV-infected patients.

Immune profiling in Puerto Rican injection drug users with and without HIV-1 infection

Antiretroviral therapy has been effective in suppressing HIV viral load and enabling people living with HIV to experience longer, more conventional lives. However, as people living with HIV are living longer, they are developing aging-related diseases prematurely and are more susceptible to comorbidities that have been linked to chronic inflammation. Coincident with HIV infection and aging, drug abuse has also been independently associated with gut dysbiosis, microbial translocation, and inflammation. Here, we hypothesized that injection drug use would exacerbate HIV-induced immune activation and inflammation, thereby intensifying immune dysfunction. We recruited 50 individuals not using injection drugs (36/50 HIV+) and 47 people who inject drugs (PWID, 12/47 HIV+). All but 3 of the HIV+ subjects were on antiretroviral therapy. Plasma immune profiles were characterized by immunoproteomics, and cellular immunophenotypes were assessed using mass cytometry. The immune profiles of HIV+/PWID-, HIV-/PWID+, and HIV+/PWID+ were each significantly different from controls; however, few differences between these groups were detected, and only 3 inflammatory mediators and 2 immune cell populations demonstrated a combinatorial effect of injection drug use and HIV infection. In conclusion, a comprehensive analysis of inflammatory mediators and cell immunophenotypes revealed remarkably similar patterns of immune dysfunction in HIV-infected individuals and in people who inject drugs with and without HIV-1 infection.

Microbiome Alterations in Alcohol Use Disorder and Alcoholic Liver Disease

Microbiome alterations are emerging as one of the most important factors that influence the course of alcohol use disorder (AUD). Recent advances in bioinformatics enable more robust and accurate characterization of changes in the composition of the microbiome. In this study, our objective was to provide the most comprehensive and up-to-date evaluation of microbiome alterations associated with AUD and alcoholic liver disease (ALD). To achieve it, we have applied consistent, state of art bioinformatic workflow to raw reads from multiple 16S rRNA sequencing datasets. The study population consisted of 122 patients with AUD, 75 with ALD, 54 with non-alcoholic liver diseases, and 260 healthy controls. We have found several microbiome alterations that were consistent across multiple datasets. The most consistent changes included a significantly lower abundance of multiple butyrate-producing families, including Ruminococcaceae, Lachnospiraceae, and Oscillospiraceae in AUD compared to HC and further reduction of these families in ALD compared with AUD. Other important results include an increase in endotoxin-producing Proteobacteria in AUD, with the ALD group having the largest increase. All of these alterations can potentially contribute to increased intestinal permeability and inflammation associated with AUD and ALD.

Through the Looking-Glass: Psychoneuroimmunology and the Microbiome-Gut-Brain Axis in the Modern Antiretroviral Therapy Era

OBJECTIVE

Depression, substance use disorders, and other neuropsychiatric comorbidities are common in people with HIV (PWH), but the underlying mechanisms are not sufficiently understood. HIV-induced damage to the gastrointestinal tract potentiates residual immune dysregulation in PWH receiving effective antiretroviral therapy. However, few studies among PWH have examined the relevance of microbiome-gut-brain axis: bidirectional crosstalk between the gastrointestinal tract, immune system, and central nervous system.

METHODS

A narrative review was conducted to integrate findings from 159 articles relevant to psychoneuroimmunology (PNI) and microbiome-gut-brain axis research in PWH.

RESULTS

Early PNI studies demonstrated that neuroendocrine signaling via the hypothalamic-pituitary-adrenal axis and autonomic nervous system could partially account for the associations of psychological factors with clinical HIV progression. This review highlights the need for PNI studies examining the mechanistic relevance of the gut microbiota for residual immune dysregulation, tryptophan catabolism, and oxytocin release as key biological determinants of neuropsychiatric comorbidities in PWH (i.e., body-to-mind pathways). It also underscores the continued relevance of neuroendocrine signaling via the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and oxytocin release in modifying microbiome-gut-brain axis functioning (i.e., mind-to-body pathways).

CONCLUSIONS

Advancing our understanding of PNI and microbiome-gut-brain axis pathways relevant to depression, substance use disorders, and other neuropsychiatric comorbidities in PWH can guide the development of novel biobehavioral interventions to optimize health outcomes. Recommendations are provided for biobehavioral and neurobehavioral research investigating bidirectional PNI and microbiome-gut-brain axis pathways among PWH in the modern antiretroviral therapy era.

Immune activation in primary HIV: influence of duration of infection, treatment, and substance use

Background

Primary human immunodeficiency virus (HIV) is characterized by dynamic changes in viral load and innate and adaptive immune responses; it is unclear the extent to which time from acquisition to antiretroviral therapy (ART) initiation and substance use impact these immunologic changes.

Methods

We studied plasma immune activation biomarkers, viral load, and CD4⁺ and CD8⁺ cell counts in participants from the Sabes primary infection study in Peru, who had been randomized to begin ART immediately after diagnosis vs 24 weeks later. We modeled influence of substance use and duration of HIV infection on biomarkers at baseline and over 24 weeks.

Results

Compared to participants enrolled >30 days after HIV acquisition, participants enrolled during acute infection (≤30 days) had higher mean interferon (IFN)–γ and IFN-α2a (1.7-fold and 3.8-fold interquartile range [IQR] higher, respectively). Participants enrolled >30 days after HIV acquisition had higher mean baseline CD8⁺ cell count (2.7 times the IQR). Alcohol use (positive phosphatidylethanol level) was associated with elevated IFN-γ, tumor necrosis factor alpha (TNF-α), and interleukin 12p70 (IL-12p70), and smoking was associated with higher macrophage inflammatory protein 1α, TNF-α, and IL-12p70. Most biomarkers declined more quickly in participants who initiated ART immediately; however, substance use and duration of HIV infection at enrollment had little influence on rate of decline.

Conclusions

IFN-γ and other biomarkers are elevated during early primary infection, when exposure to HIV antigens is high. Immune activation decreased most quickly in those who started ART during acute/early primary infection. Higher CD8⁺ cell counts and a trend toward higher soluble CD163 levels during the 30 days after acquisition suggest the onset of compensatory responses and immune exhaustion.

Chronic Alcohol Exposure Among People Living with HIV Is Associated with Innate Immune Activation and Alterations in Monocyte Phenotype and Plasma Cytokine Profile

Despite advances in antiretroviral therapy, chronic immune activation continues to be observed among individuals with well-controlled HIV viral loads, and is associated with non-AIDS defining morbidities among people living with HIV. Alcohol use disorder impacts a significant proportion of individuals living with HIV, and alcohol exposure is known to damage the intestinal epithelium which may increase translocation of pathogens and their molecular products, driving systemic immune activation and dysregulation. The aim of this study was to determine if adults living with HIV with well-controlled viral loads, who also suffer from alcohol use disorder with and without hepatitis C virus co-infection (n=23), exhibit evidence of advanced systemic immune activation, intestinal damage, and microbial translocation, as compared to adults living with HIV who are not exposed to chronic alcohol or other substances of abuse (n=29). The impact of a 1-month intervention to treat alcohol-use disorder was also examined. Alcohol-use disorder was associated with evidence of advanced innate immune activation, alterations in monocyte phenotype including increased expression of Toll-like receptor 4, increased burden of stimulatory ligands for Toll-like receptor 4, and alterations in plasma cytokine signature, most notably elevations in soluble CD40 ligand and transforming growth factor beta. Alcohol-associated immune activation was more pronounced among individuals with hepatitis C virus co-infection. Although the 1-month intervention to treat alcohol use disorder did not result in significant reductions in the interrogated indicators of immune activation, our findings suggest that chronic alcohol exposure is a major modifiable risk factor for chronic immune activation and dysregulation among people-living with HIV.

Pathophysiological Consequences of At-Risk Alcohol Use; Implications for Comorbidity Risk in Persons Living With Human Immunodeficiency Virus

At-risk alcohol use is a significant risk factor associated with multisystemic pathophysiological effects leading to multiorgan injury and contributing to 5.3% of all deaths worldwide. The alcohol-mediated cellular and molecular alterations are particularly salient in vulnerable populations, such as people living with HIV (PLWH), diminishing their physiological reserve, and accelerating the aging process. This review presents salient alcohol-associated mechanisms involved in exacerbation of cardiometabolic and neuropathological comorbidities and their implications in the context of HIV disease. The review integrates consideration of environmental factors, such as consumption of a Western diet and its interactions with alcohol-induced metabolic and neurocognitive dyshomeostasis. Major alcohol-mediated mechanisms that contribute to cardiometabolic comorbidity include impaired substrate utilization and storage, endothelial dysfunction, dysregulation of the renin-angiotensin-aldosterone system, and hypertension. Neuroinflammation and loss of neurotrophic support in vulnerable brain regions significantly contribute to alcohol-associated development of neurological deficits and alcohol use disorder risk. Collectively, evidence suggests that at-risk alcohol use exacerbates cardiometabolic and neurocognitive pathologies and accelerates biological aging leading to the development of geriatric comorbidities manifested as frailty in PLWH.

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.