Measures of Adipose Tissue Redistribution and Atherosclerotic Coronary Plaque in HIV

The association between the visceral to subcutaneous abdominal fat ratio and the risk of cardiovascular diseases: a systematic review

BACKGROUND

Cardiovascular diseases (CVDs) are the primary cause of mortality globally. The prevalence of obesity is rising worldwide; there seems to be a significant positive association between obesity and CVDs. The distribution of fat in the abdominal area in the form of visceral (VAT) or subcutaneous adipose tissue (SAT) affects the risk of CVDs. The aim of the present study was to conduct a systematic review of the available literature regarding the association between the VAT-to-SAT ratio and CVDs.

METHODS

A comprehensive search strategy was used to retrieve all human observational studies indexed in PubMed, Scopus and Google Scholar databases/search engines (from Jan 2000 up to Oct 2023). The VAT-to-SAT or SAT-to-VAT ratio was an independent variable and various cardiovascular diseases, including hypertension, atherosclerosis, coronary heart disease, cerebrovascular disease and heart failure, were considered as outcomes of interest.

RESULTS

Out of 1173 initial studies, 910 papers were screened. Based on the inclusion criteria, 883 papers were excluded. Finally, 27 papers (18 cross-sectional and 9 cohort studies) published between 2010 and 2023 which met the inclusion criteria were reviewed.

CONCLUSIONS

The distribution of abdominal fat seems to be associated with the risk of CVDs; the majority of the evidence suggests that a higher abdominal VAT-to-SAT ratio is associated with the development of CVDs. Therefore, this ratio can be used as a prognostic indicator for CVDs.

TRIAL REGISTRATION

Not applicable.

Large lessons learned from small vessels: coronary microvascular dysfunction in HIV

PURPOSE OF REVIEW

Large cohort studies have consistently shown the presence of heart failure is approximately doubled among persons with HIV (PWH). Early studies of cardiovascular disease (CVD) in HIV were primarily focused on atherosclerotic burden, and we now have a greater understanding of large vessel disease in HIV. More recent studies have begun to inform us about small vessel disease, or coronary microvascular dysfunction (CMD), in HIV. CMD is recognized to be an important risk factor for adverse events related to heart failure, associated with cardiovascular mortality, and often presents without overt atherosclerotic disease.

RECENT FINDINGS

In this review, we highlight implications for CMD and relevant clinical studies in HIV. Inflammation and endothelial dysfunction, well known risk factors in HIV, may mediate the pathogenesis of CMD. Initial studies suggest that CMD worsens with ART initiation. Newer studies reveal CMD is present among well treated PWH without known CVD. In addition, myocardial flow reserve (MFR), a marker of CMD, is reduced in HIV similar to diabetes. There also appears to be sex differences, such that CMD is worse among women vs. men with HIV.

SUMMARY

Alterations in the coronary microvasculature may be an important mediator of subclinical myocardial dysfunction that deserves further clinical attention among PWH without known CVD.

Visceral Adiposity Index as a Measure of Cardiovascular Disease in Persons With Human Immunodeficiency Virus

Background

Persons with well-treated human immunodeficiency virus (HIV) demonstrate a 2-fold higher risk of cardiovascular disease (CVD), which may be related to excess visceral adipose tissue (VAT). The visceral adiposity index (VAI) is a score to approximate VAT by combining biochemical measures with anthropometrics without quantification by imaging. We evaluated VAI in association with cardiometabolic factors among persons with HIV (PWH).

Methods

Forty-five PWH on antiretroviral therapy and virologically controlled with increased abdominal VAT (VAT area >110 cm2 on CT) and no known CVD were included. VAI was calculated using standard sex-specific formulas. Coronary plaque was assessed using coronary CT angiography.

Results

Participants were predominantly male (73%), white (53%), and non-Hispanic (84%), with a mean age of 55 (standard deviation, 7) years. Among PWH, median VAI was calculated to be 4.9 (interquartile range [IQR], 2.8-7.3). Log VAI correlated with log VAT (r = 0.59, P < .0001) and anthropometric measures (body mass index: r = 0.36, P = .02; waist circumference: r = 0.43, P = .004; waist-to-hip ratio: r = 0.33, P = .03). Participants with coronary plaque had a higher VAI compared to those without coronary plaque (median, 5.3 [IQR, 3.4-10.5] vs 2.8 [IQR, 1.8-5.0]; P = .004). VAI (area under the curve = 0.760, P = .008) performed better than the atherosclerotic CVD risk score to predict the presence of plaque in receiver operating characteristic analyses.

Conclusions

VAI may be a useful biomarker of metabolic dysfunction and increased CVD risk that may occur with VAT accumulation in PWH.

Clinical Trials Registration

NCT02740179.

Update on acquired hypogonadism in men living with HIV: pathogenesis, clinic, and treatment

Hypogonadism is a frequent finding among men living with HIV (MLWH) and it seems to occur earlier in comparison with the general male population. Although the prevalence of hypogonadism in MLWH has significantly lowered thanks to advancements in medical management, it remains high if compared with age-matched HIV-uninfected men, ranging from 13% to 40% in the age group of 20-60 years. Signs and symptoms of low serum testosterone (T) in MLWH are cause of concern since they are non-specific, of mild-to-moderate degree, and often overlapping with those of infection per se. For these reasons, hypogonadism can be underestimated in the absence of targeted laboratory blood examinations. With regard to the etiological factors involved in the T decrease, emerging evidence has suggested the functional nature of hypogonadism in MLWH, pointing out the mutual relationship between sex steroids, health status, comorbidities, and HIV-related factors. In agreement with this hypothesis, a therapeutic approach aiming at improving or reversing concomitant diseases through lifestyle changes (e.g. physical activity) rather than pharmacological T treatment should be theoretically considered. However, considering both patient's barriers to lifestyle changes to be maintained overtime and the lack of evidence-based data on the efficacy of lifestyle changes in normalizing serum T in MLWH, T therapy remains an option when other non-pharmacological interventions are ineffective as well as for all other functional forms of hypogonadism. From this perspective, the traditional therapeutic management of male hypogonadism in MLWH, especially the role of T supplementation, should be revised in the light of the probable functional nature of hypogonadism by considering a good balance between benefits and harmful. This narrative review presents an overview of current knowledge on hypogonadism in MLWH, deepening the factors driving and taking part in T decrease, providing advice for the clinical approach, and underlining the importance of individualized treatment aiming at optimizing non-gonadal comorbidities and thus avoiding over-, or even unnecessary, treatment with T.

Ectopic Fat and Cardiac Health in People with HIV: Serious as a Heart Attack

PURPOSE OF REVIEW

This study aims to summarize knowledge of alterations in adipose tissue distribution among people with HIV (PWH), with a focus on the cardiac depot and how this relates to the known higher risk of cardiovascular disease in this unique population.

RECENT FINDINGS

Similar to the general population, cardiac fat depots mirror visceral adipose tissue in PWH. However, altered fat distribution, altered fat quality, and higher prevalence of enlarged epicardial adipose tissue depots are associated with increased coronary artery disease among PWH. Adipose tissue disturbances present in PWH ultimately contribute to increased risk of cardiovascular disease beyond traditional risk factors. Future research should aim to understand how regulating adipose tissue quantity and quality can modify cardiovascular risk.

Cardiovascular Disease Risk Among Transgender People with HIV

PURPOSE OF REVIEW

Transgender individuals are at disproportionate risk for HIV infection, with prevalence rates highest among transgender women of color. Antiretroviral therapy (ART)-treated people with HIV (PWH) are at increased risk for cardiovascular disease (CVD), in relation to persistent systemic immune activation and metabolic dysregulation. The purpose of this review is to examine parameters which may affect CVD risk among transgender PWH.

RECENT FINDINGS

Among transgender women and men, prospective longitudinal studies have shown that gender-affirming hormonal therapy (GAHT) is associated with select deleterious cardiometabolic effects such as increases in visceral adipose tissue. Retrospective studies among transgender women and men suggest an increase in CVD risk, such as venous thromboembolism, cerebrovascular accidents, and myocardial infarction. Studies among transgender PWH adhering to GAHT and ART suggest heightened systemic immune activation/inflammation. Prospective longitudinal studies assessing factors associated with increased CVD events among transgender PWH are needed to guide the development of CVD prevention strategies in this at-risk population.

Altered pattern of circulating miRNAs in HIV lipodystrophy perturb key adipose differentiation and inflammation pathways

We identified a microRNA (miRNA) profile characterizing HIV lipodystrophy and explored the downstream mechanistic implications with respect to adipocyte biology and the associated clinical phenotype. miRNA profiles were extracted from small extracellular vesicles (sEVs) of HIV-infected individuals with and without lipodystrophic changes and individuals without HIV, among whom we previously showed significant reductions in adipose Dicer expression related to HIV. miR-20a-3p was increased and miR-324-5p and miR-186 were reduced in sEVs from HIV lipodystrophic individuals. Changes in these miRNAs correlated with adipose Dicer expression and clinical markers of lipodystrophy, including fat redistribution, insulin resistance, and hypertriglyceridemia. Human preadipocytes transfected with mimic miR-20a-3p, anti–miR-324-5p, or anti–miR-186 induced consistent changes in latent transforming growth factor beta binding protein 2 (Ltbp2), Wisp2, and Nebl expression. Knockdown of Ltbp2 downregulated markers of adipocyte differentiation (Fabp4, Pparγ, C/ebpa, Fasn, adiponectin, Glut4, CD36), and Lamin C, and increased expression of genes involved in inflammation (IL1β, IL6, and Ccl20). Our studies suggest a likely unique sEV miRNA signature related to dysregulation of Dicer in adipose tissue in HIV. Enhanced miR-20a-3p or depletion of miR-186 and miR-324-5p may downregulate Ltbp2 in HIV, leading to dysregulation in adipose differentiation and inflammation, which could contribute to acquired HIV lipodystrophy and associated metabolic and inflammatory perturbations.

Recent data on adipose tissue, insulin resistance, diabetes and dyslipidaemia in antiretroviral therapy controlled HIV-infected persons

PURPOSE OF REVIEW

Increased total body fat with truncal redistribution is common in antiretroviral therapy (ART)-controlled persons living with HIV(PLWH), leading to insulin resistance, prediabetes/diabetes and dyslipidaemia. We address these topics here.

RECENT FINDINGS

Most antiretrovirals are associated with gain in trunk fat, including visceral adipose tissue (VAT). Protease-inhibitors could inhibit white fat ability to dissipate energy (i.e. beiging) favouring fat gain. Expansion of VAT is associated with a pro-inflammatory profile linked to the tryptophan-kynurenine pathway and CD4+ subtypes. ART-associated increased adipose tissue (AT) quantity leads to decreased AT density, insulin resistance and dyslipidaemia that could be improved by lifestyle modifications.PLWH present high level of insulin resistance, regardless of their treatment, and a higher prevalence of prediabetes, but not diabetes, than noninfected persons. Otherwise, HbA1c values appear inaccurate to diagnose prediabetes/diabetes in PLWH.ART-related-dyslipidaemia is characterized by elevated LDL-C and/or high triglycerides and reduced HDL-C. Whereas treatment with protease inhibitors generally results in worsened lipid values, treatment with integrase-strand-transfer-inhibitors is associated with a better profile. Tenofovir-alafenamide is associated with higher lipid levels than tenofovir-disoproxil-fumarate. Treatment of LDL-C-dyslipidaemia could benefit, in statin-insufficiently controlled patients, from the class of proprotein-convertase-subtilsin-kenin-type-9 (PCSK-9) inhibitors.

SUMMARY

Lifestyle modifications are mandatory to reduce fat and improve dysglycaemia/dyslipidaemia. New drugs can efficiently control diabetes and LDL-C-dyslipidaemia.

Relationship of Telomere Length to Fat Redistribution in HIV

Persons with HIV demonstrate increased risk for aging-associated complications and have reduced telomere length (TL) compared with age-matched persons without HIV. Our data show that greater visceral fat is related to reduced TL in HIV, independent of age and smoking. Fat redistribution may be a relevant mediator of TL attrition in HIV.