Chronic Binge Alcohol Administration Increases Intestinal T-Cell Proliferation and Turnover in Rhesus Macaques

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.

Alcohol Impairs Immunometabolism and Promotes Naïve T Cell Differentiation to Pro-Inflammatory Th1 CD4+ T Cells

CD4+ T cell differentiation to pro-inflammatory and immunosuppressive subsets depends on immunometabolism. Pro-inflammatory CD4+ subsets rely on glycolysis, while immunosuppressive Treg cells require functional mitochondria for their differentiation and function. Previous pre-clinical studies have shown that ethanol (EtOH) administration increases pro-inflammatory CD4+ T cell subsets; whether this shift in immunophenotype is linked to alterations in CD4+ T cell metabolism had not been previously examined. The objective of this study was to determine whether ethanol alters CD4+ immunometabolism, and whether this affects CD4+ T cell differentiation. Naïve human CD4+ T cells were plated on anti-CD3 coated plates with soluble anti-CD28, and differentiated with IL-12 in the presence of ethanol (0 and 50 mM) for 3 days. Both Tbet-expressing (Th1) and FOXP3-expressing (Treg) CD4+ T cells increased after differentiation. Ethanol dysregulated CD4+ T cell differentiation by increasing Th1 and decreasing Treg CD4+ T cell subsets. Ethanol increased glycolysis and impaired oxidative phosphorylation in differentiated CD4+ T cells. Moreover, the glycolytic inhibitor 2-deoxyglucose (2-DG) prevented the ethanol-mediated increase in Tbet-expressing CD4+ T cells but did not attenuate the decrease in FOXP3 expression in differentiated CD4+ T cells. Ethanol increased Treg mitochondrial volume and altered expression of genes implicated in mitophagy and autophagosome formation (PINK1 and ATG7). These results suggest that ethanol impairs CD4+ T cell immunometabolism and disrupts mitochondrial repair processes as it promotes CD4+ T cell differentiation to a pro-inflammatory phenotype.

Translational Approaches with Antioxidant Phytochemicals against Alcohol-Mediated Oxidative Stress, Gut Dysbiosis, Intestinal Barrier Dysfunction, and Fatty Liver Disease

Emerging data demonstrate the important roles of altered gut microbiomes (dysbiosis) in many disease states in the peripheral tissues and the central nervous system. Gut dysbiosis with decreased ratios of Bacteroidetes/Firmicutes and other changes are reported to be caused by many disease states and various environmental factors, such as ethanol (e.g., alcohol drinking), Western-style high-fat diets, high fructose, etc. It is also caused by genetic factors, including genetic polymorphisms and epigenetic changes in different individuals. Gut dysbiosis, impaired intestinal barrier function, and elevated serum endotoxin levels can be observed in human patients and/or experimental rodent models exposed to these factors or with certain disease states. However, gut dysbiosis and leaky gut can be normalized through lifestyle alterations such as increased consumption of healthy diets with various fruits and vegetables containing many different kinds of antioxidant phytochemicals. In this review, we describe the mechanisms of gut dysbiosis, leaky gut, endotoxemia, and fatty liver disease with a specific focus on the alcohol-associated pathways. We also mention translational approaches by discussing the benefits of many antioxidant phytochemicals and/or their metabolites against alcohol-mediated oxidative stress, gut dysbiosis, intestinal barrier dysfunction, and fatty liver disease.

Role of non-Genetic Risk Factors in Exacerbating Alcohol-related organ damage

This review provides a summary of the symposium titled "Role of Non-Genetic Risk Factors in Exacerbating Alcohol-Related Organ Damage", which was held at the 42nd Annual Meeting of the Research Society on Alcoholism. The goals of the symposium were to provide newer insights into the role of non-genetic factors, including specific external factors, notably infectious agents or lifestyle factors, that synergistically act to exacerbate alcohol pathogenicity to generate more dramatic downstream biological defects. This summary of the symposium will benefit junior/senior basic scientists and clinicians currently investigating/treating alcohol-induced organ pathology, as well as undergraduate, graduate, and post-graduate students and fellows.

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

BACKGROUND

Inflammation persists among persons with human immunodeficiency virus (PWH) despite effective antiretroviral therapy and may contribute to T-cell dysfunction. Alcohol use is prevalent among PWH and promotes intestinal leak, dysbiosis, and a proinflammatory milieu. Whether alcohol use is associated with T-cell late differentiation remains to be investigated.

METHODS

Data and samples from PWH (N = 359 of 365) enrolled in the New Orleans Alcohol Use in HIV Study were used. Alcohol use was assessed by self-report (Alcohol Use Disorders Identification Test; lifetime alcohol exposure; 30-day Alcohol Timeline Followback) and phosphatidylethanol (PEth) quantitation. In a subset of participants, fecal bacterial content was assessed by ribosomal 16S marker gene deep sequencing and quantitative polymerase chain reaction. Intestinal leak was assessed by fecal-to-plasma α-1-antitrypsin (A1AT) enzyme-linked immunosorbent assay ratio. Peripheral T-cell populations were quantified by flow cytometry.

RESULTS

Alcohol Use Disorder Identification Test scores were positively associated with activated-senescent, exhausted, and terminal effector memory CD45RA+CD8+ but not CD4+ T cells (cells/μL) after confounder adjustment (P < .050). Phosphatidylethanol was positively associated with A1AT (P < .050). The PEth and activated-senescent CD8+ were associated with bacterial β-diversity (P < .050) and positively associated with the relative abundance of coabundant Prevotellaceae members (q < .100).

CONCLUSIONS

Alcohol use among PWH is associated with CD8+ T-cell late differentiation, intestinal leak, and dysbiosis. Alcohol-associated dysbiosis is implicated in CD8+ T-cell senescence.

Chronic ethanol consumption alters lamina propria leukocyte response to stimulation in a region-dependent manner

Chronic heavy alcohol consumption, also referred to as chronic heavy drinking (CHD), results in intestinal injury characterized by increased permeability, dysbiosis, nutrient malabsorption, potentially higher susceptibility to infection, and increased risk of colorectal cancer. However, our understanding of the mechanisms by which CHD results in intestinal damage remains incomplete. Here, we investigated the impact of chronic drinking on transcriptional and functional responses of lamina propria leukocytes (LPLs) isolated from the 4 major gut sections. Although no significant differences were detected between LPLs isolated from the ethanol and control groups at resting state within each major gut section, our analysis uncovered key regional differences in composition and function of LPLs independent of alcohol consumption. However, in response to phorbol myristate acetate and ionomycin, duodenal LPLs from ethanol-drinking animals generated a dampened response, whereas jejunal and ileal LPLs from ethanol-drinking animals produced a heightened response. Transcriptional responses following stimulation were pronounced in ileal and duodenal LPLs from the ethanol-drinking group but less evident in jejunal and colonic LPLs compared with controls, suggesting a more significant impact of alcohol on these gut regions. The altered intestinal LPL function detected in our study reveals remarkable region specificity and novel insight into potential mechanisms of intestinal injury associated with CHD.-Barr, T., Lewis, S. A., Sureshchandra, S., Doratt, B., Grant, K. A., Messaoudi, I. Chronic ethanol consumption alters lamina propria leukocyte response to stimulation in a region-dependent manner.

Impact of Alcohol on HIV Disease Pathogenesis, Comorbidities and Aging: Integrating Preclinical and Clinical Findings

Short Summary

: Effective combined antiretroviral therapy regimens have extended survival of persons living with HIV (PLWH). Heavy alcohol consumption is common in PLWH. This overview integrates evidence from clinical and preclinical research to identify salient alcohol-related mechanisms and comorbidities contributing to disease pathogenesis and accelerated aging and senescence in PLWH.

Markers of Microbial Translocation and Immune Activation Predict Cognitive Processing Speed in Heavy-Drinking Men Living with HIV

HIV infection and alcohol use disorder are associated with deficits in neurocognitive function. Emerging evidence points to pro-inflammatory perturbations of the gut-brain axis as potentially contributing to neurocognitive impairment in the context of HIV and chronic heavy alcohol use. This study examined whether plasma markers of microbial translocation (LPS) from the gastrointestinal tract and related immune activation (sCD14, EndoCAb) were associated with neurocognition in 21 men living with HIV who were virally suppressed on antiretroviral therapy. All participants met federal criteria for heavy drinking and were enrolled in a randomized controlled trial (RCT) of a brief alcohol intervention. This secondary analysis utilized blood samples and cognitive scores (learning, memory, executive function, verbal fluency, and processing speed) obtained at baseline and three-month follow-up of the RCT. In generalized estimating equation models, LPS, sCD14, and EndoCAb individually were significant predictors of processing speed. In a model with all biomarkers, higher LPS and sCD14 both remained significant predictors of lower processing speed. These preliminary findings suggest that inflammation stemming from HIV and/or alcohol could have negative effects on the gut-brain axis, manifested as diminished processing speed. Associations of microbial translocation and immune activation with processing speed in heavy-drinking PLWH warrant further investigation in larger-scale studies.

Validation of RPS13 as a reference gene for absolute quantification of SIV RNA in tissue of rhesus macaques

Persistent HIV reservoirs and the absolute quantification of viral RNA copies in tissues have become a prominent focus of multiple areas ofHIV/SIV research. Absolute quantification of viral RNA via reverse transcription, quantitative PCR (RT-qPCR) necessitates the use of an appropriate RNA reference gene whose expression is unaffected by both experimental and confounding conditions. In this study, we demonstrate the utility of ribosomal protein S13 mRNA (RPS13) as a stable, medium abundance reference gene for RT-qPCR normalization of HIV/SIV RNA copy number. We developed a RPS13 RNA standard assay utilizing an in vitro RNA transcript for normalization of absolute SIV RNA quantities in tissues reservoirs. The RT-qPCR assay showed a high degree of repeatability and reproducibility across RNA levels appropriate for absolute SIV quantification. In assessing the utility of RPS13 as a reference gene, limited variation in the absolute, inter-tissue quantities of RPS13 mRNA was observed within multiple tissue samples obtained from rhesus macaques (average CV=2.86%). We demonstrate rhesus macaque RPS13 mRNA expression is not affected by alcohol administration, SIV infection, or antiviral therapy (PMPA/FTC). Additionally, assay functionality was validated for normalization of SIV copy number using cellular RNA prepared from samples of variable RNA integrity. RPS13 is a suitable reference gene for normalization of absolute SIV RNA quantities in tissues and is most appropriate for intra-tissue or similar tissue type comparisons of SIV copy number.