Intestinal Dysbiosis and Markers of Systemic Inflammation in Viscerally and Generally Obese Persons Living With HIV

Adipose Tissue Dysfunction and Energy Balance Paradigms in People Living With HIV

Over the past 4 decades, the clinical care of people living with HIV (PLWH) evolved from treatment of acute opportunistic infections to the management of chronic, noncommunicable comorbidities. Concurrently, our understanding of adipose tissue function matured to acknowledge its important endocrine contributions to energy balance. PLWH experience changes in the mass and composition of adipose tissue depots before and after initiating antiretroviral therapy, including regional loss (lipoatrophy), gain (lipohypertrophy), or mixed lipodystrophy. These conditions may coexist with generalized obesity in PLWH and reflect disturbances of energy balance regulation caused by HIV persistence and antiretroviral therapy drugs. Adipocyte hypertrophy characterizes visceral and subcutaneous adipose tissue depot expansion, as well as ectopic lipid deposition that occurs diffusely in the liver, skeletal muscle, and heart. PLWH with excess visceral adipose tissue exhibit adipokine dysregulation coupled with increased insulin resistance, heightening their risk for cardiovascular disease above that of the HIV-negative population. However, conventional therapies are ineffective for the management of cardiometabolic risk in this patient population. Although the knowledge of complex cardiometabolic comorbidities in PLWH continues to expand, significant knowledge gaps remain. Ongoing studies aimed at understanding interorgan communication and energy balance provide insights into metabolic observations in PLWH and reveal potential therapeutic targets. Our review focuses on current knowledge and recent advances in HIV-associated adipose tissue dysfunction, highlights emerging adipokine paradigms, and describes critical mechanistic and clinical insights.

Evaluating immunological and inflammatory changes of treatment-experienced people living with HIV switching from first-line triple cART regimens to DTG/3TC vs. B/F/TAF: the DEBATE trial

Background

The aim of this randomized clinical trial (RCT) was to compare immunological changes in virally suppressed people living with HIV (PLWH) switching from a three-drug regimen (3DR) to a two-drug regimen (2DR).

Methods

An open-label, prospective RCT enrolling PLWH receiving a 3DR who switched to bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) or dolutegravir/lamivudine (DTG/3TC) was performed. Blood was taken at baseline and months 6 and 12. The primary outcome was the change in CD4+ or CD8+ T-cell counts and CD4/CD8 ratio over time points. The secondary outcomes were the changes in immunological and inflammatory parameters. Parametric mixed-linear models with random intercepts and slopes were fitted separately for each marker after controlling for potential confounders.

Results

Between the two arms (33 PLWH each), there was no difference in CD4+ or CD8+ T cells, CD4/CD8 ratio, and IL-6 trajectories. PLWH switching to DTG/3TC had increased levels of both transitional memory and terminally differentiated CD4+ T cells (arm-time interaction p-value = 0.02) and to a lesser extent for the corresponding CD8+ T-cell subsets (p = 0.09). Significantly lower levels of non-classical monocytes were detected in the B/F/TAF arm at T6 (diff = -6.7 cells/mm3; 95% CI; -16, +2.6; p-value for interaction between arm and time = 0.03). All differences were attenuated at T12.

Conclusion

No evidence for a difference in absolute CD4+ and CD8+ T-cell counts, CD4/CD8 ratio, and IL-6 trajectories by study arm over 12 months was found. PLWH on DTG/3TC showed higher levels of terminally differentiated and exhausted CD4+ and CD8+ T lymphocytes and non-classical monocytes at T6. Further studies are warranted to better understand the clinical impact of our results.

Clinical Trial Registration

https://clinicaltrials.gov, identifier NCT04054089.

Multiomic analysis reveals microbiome-related relationships between cocaine use and metabolites

OBJECTIVE

Over 19 million individuals globally have a cocaine use disorder, a significant public health crisis. Cocaine has also been associated with a pro-inflammatory state and recently with imbalances in the intestinal microbiota as compared to nonuse. The objective of this pilot study was to characterize the gut microbiota and plasma metabolites in people with HIV (PWH) who use cocaine compared with those who do not.

DESIGN

Cross-sectional study.

METHODS

A pilot study in PWH was conducted on 25 cocaine users and 25 cocaine nonusers from the Miami Adult Studies on HIV cohort. Stool samples and blood plasma were collected. Bacterial composition was characterized using 16S rRNA sequencing. Metabolomics in plasma were determined using gas and liquid chromatography/mass spectrometry.

RESULTS

The relative abundances of the Lachnopspira genus, Oscillospira genus, Bifidobacterium adolescentis species, and Euryarchaeota phylum were significantly higher in the cocaine- using PWH compared to cocaine-nonusing PWH. Cocaine-use was associated with higher levels of several metabolites: products of dopamine catabolism (3-methoxytyrosine and 3-methoxytyramine sulfate), phenylacetate, benzoate, butyrate, and butyrylglycine.

CONCLUSIONS

Cocaine use was associated with higher abundances of taxa and metabolites known to be associated with pathogenic states that include gastrointestinal conditions. Understanding key intestinal bacterial functional pathways that are altered due to cocaine use in PWH will provide a better understanding of the relationships between the host intestinal microbiome and potentially provide novel treatments to improve health.

Obesity and the increased risk for COVID-19: mechanisms and nutritional management

The global COVID-19 (coronavirus disease 2019) pandemic has become a complex problem that overlaps with a growing public health problem, obesity. Obesity alters different components of the innate and adaptive immune responses, creating a chronic and low-grade state of inflammation. Nutritional status is closely related to a better or worse prognosis of viral infections. Excess weight has been recognised as a risk factor for COVID-19 complications. In addition to the direct risk, obesity triggers other diseases such as diabetes and hypertension, increasing the risk of severe COVID-19. The present review explains the diets that induce obesity and the importance of different foods in this process. We also review tissue disruption in obesity, leading to impaired immune responses and the possible mechanisms by which obesity and its co-morbidities increase COVID-19 morbidity and mortality. Nutritional strategies that support the immune system in patients with obesity and with COVID-19 are also discussed in light of the available data, considering the severity of the infection. The discussions held may contribute to combating this global emergency and planning specific public health policy.

Gut Microbiome Changes Associated with Epithelial Barrier Damage and Systemic Inflammation during Antiretroviral Therapy of Chronic SIV Infection

Gut dysbiosis is a common feature associated with the chronic inflammation of HIV infection. Toward understanding the interplay of chronic treated HIV infection, dysbiosis, and systemic inflammation, we investigated longitudinal fecal microbiome changes and plasma inflammatory markers in the nonhuman primate model. Following simian immunodeficiency virus (SIV) infection in rhesus macaques, significant changes were observed in several members of the phylum Firmicutes along with an increase in Bacteroidetes. Viral suppression with antiretroviral therapy (ART) resulted in an early but partial recovery of compositional changes and butyrate producing genes in the gut microbiome. Over the course of chronic SIV infection and long-term ART, however, the specific loss of Faecalibacterium prausnitzii and Treponema succinifaciens significantly correlated with an increase in plasma inflammatory cytokines including IL-6, G-CSF, I-TAC, and MIG. Further, the loss of T. succinifaciens correlated with an increase in circulating biomarkers of gut epithelial barrier damage (IFABP) and microbial translocation (LBP and sCD14). As F. prausnitzii and T. succinifaciens are major short-chain fatty acid producing bacteria, their sustained loss during chronic SV-ART may contribute to gut inflammation and metabolic alterations despite effective long-term control of viremia. A better understanding of the correlations between the anti-inflammatory bacterial community and healthy gut barrier functions in the setting of long-term ART may have a major impact on the clinical management of inflammatory comorbidities in HIV-infected individuals.

Gastrointestinal Dysfunction and HIV Comorbidities

PURPOSE OF REVIEW

Gut dysfunction and resulting chronic low-grade inflammation have been linked to metabolic and chronic diseases in the general population. In this review, we present recently published studies of HIV-associated gut dysfunction and comorbidities including obesity, diabetes, cardiovascular disease, liver disease, and neurocognitive disease.

RECENT FINDINGS

Biomarkers of microbial translocation, dysbiosis, or intestinal epithelial integrity have been used to investigate relationships between HIV-associated gut dysfunction and metabolic, cardiovascular, and neurologic complications. Many studies point to worsened comorbidities associated with gut dysfunction in people with HIV (PWH), but some studies show mixed results, and thus, the data are still inconclusive and limited to surrogate biomarkers rather than direct intestinal assessments. Inflammation and immune activation stemming from changes in intestinal epithelial integrity and dysbiosis are present in PWH and relate to metabolic, cardiovascular, and neurologic complications of HIV. However, future investigations, especially future studies that directly assess intestinal pathology, are needed to investigate the direct contributory role of gastrointestinal dysfunction to comorbidities of HIV.

The Bacterium Akkermansia muciniphila: A Sentinel for Gut Permeability and Its Relevance to HIV-Related Inflammation

Gut dysbiosis, namely dysregulation of the intestinal microbiota, and increased gut permeability lead to enhanced inflammation and are commonly seen in chronic conditions such as obesity and aging. In people living with HIV (PLWH), several lines of evidence suggest that a depletion of gut CD4 T-cells is associated with gut dysbiosis, microbial translocation and systemic inflammation. Antiretroviral therapy (ART) rapidly controls viral replication, which leads to CD4 T-cell recovery and control of the disease. However, gut dysbiosis, epithelial damage and microbial translocation persist despite ART, increasing risk of developing inflammatory non-AIDS comorbidities such as cardiovascular disease, diabetes mellitus, liver steatosis and cancer. In addition to ART, an emerging research priority is to discover strategies to improve the gut microbial composition and intestinal barrier function. Probiotic interventions have been extensively used with controversial benefits in humans. Encouragingly, within the last decade, the intestinal symbiotic bacterium Akkermansia muciniphila has emerged as the “sentinel of the gut.” A lower abundance of A. muciniphila has been shown in diabetic and obese people as well as in PLWH. Interventions with high levels of polyphenols such as tea or diets rich in fruit, the antibiotic vancomycin and the antidiabetic drug metformin have been shown to increase A. muciniphila abundance, contributing to improved metabolic function in diabetic and obese individuals. We hypothesize that gut microbiota rich in A. muciniphila can reduce microbial translocation and inflammation, preventing occurrences of non-AIDS comorbidities in PLWH. To this aim, we will discuss the protective effect of A. muciniphila and its potential applications, paving the way toward novel therapeutic strategies to improve gut health in PLWH.