Viral mechanisms of adipose dysfunction: lessons from HIV-1 Vpr

The potential molecular implications of adiponectin in the evolution of SARS-CoV-2: Inbuilt tendency

Adiponectin (APN) is an adipokine concerned in the regulation of glucose metabolism, insulin sensitivity and fatty acid oxidation. APN plays a critical role in viral infections by regulating the immune response through its anti-inflammatory/pro-inflammatory axis. Reduction of APN may augment the severity of viral infections because APN inhibits immune cells’ response via suppression of inflammatory signaling pathways and stimulation of adenosine monophosphate protein kinase (AMPK). Moreover, APN inhibits the stimulation of nuclear factor kappa B (NF-κB) and regulates the release of pro-inflammatory cytokines, such as tumor necrosis factor alpha (TNF-α) and interleukins (IL-18, IL-6). In COVID-19, abnormalities of the fatty tissue due to oxidative stress (OS) and hyperinflammation may inhibit the production and release of APN. APN has lung-protective effect and can prevent SARS-CoV-2-induced acute lung injury (ALI) through the amelioration of endoplasmic reticulum (ER) stress, endothelial dysfunction (ED) and stimulation of peroxisome proliferator-activated receptor-alpha (PPAR-α). It has been established that there is a potential correlation between inflammatory signal transduction pathways and APN that contributes to the development of SARS-CoV-2 infections. Deregulation of these molecular pathways affects the expression of APN and vice versa. In addition, the reduction of APN effect in SARS-CoV-2 infection could be a potential cause of the exacerbation of pro-inflammatory effects which are associated with the disease severity. In this context, exploratory, developmental, and extensive prospective studies are necessary.

Expert Panel Review on Nonalcoholic Fatty Liver Disease in Persons With Human Immunodeficiency Virus

Nonalcoholic fatty liver disease (NAFLD) affects 25% of adults in the general population and is a disease spectrum ranging from steatosis to nonalcoholic steatohepatitis (NASH) to end-stage liver disease. NAFLD is an independent risk factor for cardiovascular disease, diabetes mellitus, and all-cause mortality, and NASH cirrhosis is a frequent indication for liver transplantation. In persons with human immunodeficiency virus (PWH), chronic liver disease is the second leading cause of non-human immunodeficiency virus-related mortality. Between 20% and 63% of PWH have NASH, and 14% to 63% have NASH with fibrosis. However, little is known about the optimal diagnostic strategies, risk factors for, and treatment of NAFLD in PWH. Here, we review current data on and identify knowledge gaps in the epidemiology, pathophysiology, diagnosis, and management of NAFLD in PWH and highlight priorities for research.

Current Considerations for Clinical Management and Care of People with HIV: Findings from the 11th Annual International HIV and Aging Workshop

The number of people with HIV (PWH) aged 50 years or older continues to steadily increase. The convergence of age- and HIV-related complications in these individuals presents a challenge for both patients and clinicians alike. New findings continue to emerge, as numerous researchers evaluate the combined impact of these two factors on quality of life, physiological systems, and mental health in PWH. Since its first occurrence in 2009, the International Workshop on HIV and Aging has served as a multidisciplinary meeting to share basic biomedical data, clinical trial results, treatment strategies, and epidemiological recommendations, toward better understanding and outcomes among like-minded scientific professionals. In this article, we share a selection of key findings presented in plenary talks at the 11th Annual International Workshop on HIV and Aging, held virtually from September 30, 2020 to October 2, 2020. We will also address the future directions of HIV and aging research, to further assess how the aging process intersects with chronic HIV.

Symptomatic gallstones and HIV in black South African women: Changing trends of gallstone disease?

BACKGROUND

The incidence of metabolic disorders in human immunodeficiency virus (HIV) endemic settings is a prevailing burden in developing countries. Cholesterol homeostasis and fat metabolism are altered by HIV and antiretroviral therapy (ART), thereby possibly contributing to complications such as gallstone formation.

OBJECTIVES

The aim of this study was to evaluate established risk factors for the formation of cholesterol gallstones in black South African women living with HIV (WLHIV).

METHOD

A case series study was conducted of all black South African women undergoing cholecystectomy for gallstone disease over a 1-year period at King Edward VIII Hospital, Durban, South Africa. Age, body mass index (BMI), family history of gallstones, oestrogen exposure and lipograms were compared between WLHIV and uninfected women. Categorical variables were tested using either the Fisher's exact test or Pearson's chi-square test. Means were compared using independent t-tests. For non-normally distributed data, the Mann-Whitney U test was used. Statistical tests were two-sided, and p-values of less than 0.05 were considered statistically significant.

RESULTS

A total of 52 patients were assessed, 34 HIV-uninfected and 18 WLHIV. The median age of WLHIV versus the uninfected women was 35 and 50 years, respectively, (p = 0.015). A statistically significant number of uninfected women were in the overweight/obese category (BMI > 25 kg/m2) compared to the normal weight category (BMI < 25 kg/m2) (p < 0.001). The number of obese WLHIV did not reach statistical significance.

CONCLUSION

The age of occurrence of gallstone disease amongst black South African WLHIV was significantly lower and fewer women were obese compared with the uninfected women with gallstone disease. These findings differ from known gallstone risk factors in other populations and in uninfected black South African women. This could be attributed to the metabolic alterations caused by HIV infection itself and/or to the long-term use of ART. Larger cohort studies are required to elucidate the role of HIV and ART in cholestatic disease.

Impact of HIV-1 Vpr manipulation of the DNA repair enzyme UNG2 on B lymphocyte class switch recombination

Background

HIV-1 Vpr encodes a 14 kDa protein that has been implicated in viral pathogenesis through modulation of several host cell functions. In addition to pro-apoptotic and cytostatic properties, Vpr can redirect cellular E3 ubiquitin ligases (such as DCAF1-Cul4A E3 ligase complex) to target many host proteins and interfere with their functions. Among them, Vpr binds the uracil DNA glycosylase UNG2, which controls genome uracilation, and induces its specific degradation leading to loss of uracil removal activity in infected cells. Considering the essential role of UNG2 in antibody diversification in B-cells, we evaluated the impact of Vpr on UNG2 fate in B lymphocytes and examined the functional consequences of UNG2 modulations on class switch recombination (CSR).

Methods

The impact of Vpr-induced UNG2 deregulation on CSR proficiency was evaluated by using virus-like particles able to deliver Vpr protein to target cells including the murine model CSR B cell line CH12F3 and mouse primary B-cells. Co-culture experiments were used to re-examine the ability of Vpr to be released by HIV-1 infected cells and to effectively accumulate in bystander B-cells. Vpr-mediated UNG2 modulations were monitored by following UNG2 protein abundance and uracil removal enzymatic activity.

Results

In this study we report the ability of Vpr to reduce immunoglobulin class switch recombination (CSR) in immortalized and primary mouse B-cells through the degradation of UNG2. We also emphasize that Vpr is released by producing cells and penetrates bystander B lymphocytes.

Conclusions

This work therefore opens up new perspectives to study alterations of the B-cell response by using Vpr as a specific CSR blocking tool. Moreover, our results raise the question of whether extracellular HIV-1 Vpr detected in some patients may manipulate the antibody diversification process that engineers an adapted response against pathogenic intruders and thereby contribute to the intrinsic B-cell humoral defect reported in infected patients.

Impact of HIV/simian immunodeficiency virus infection and viral proteins on adipose tissue fibrosis and adipogenesis

OBJECTIVE

HIV-infected patients receiving antiretroviral treatment (ART) often present adipose tissue accumulation and/or redistribution. adipose tissue has been shown to be an HIV/SIV reservoir and viral proteins as Tat or Nef can be released by infected immune cells and exert a bystander effect on adipocytes or precursors. Our aim was to demonstrate that SIV/HIV infection per se could alter adipose tissue structure and/or function.

DESIGN

Morphological and functional alterations of subcutaneous (SCAT) and visceral adipose tissue (VAT) were studied in SIV-infected macaques and HIV-infected ART-controlled patients. To analyze the effect of Tat or Nef, we used human adipose stem cells (ASCs) issued from healthy donors, and analyzed adipogenesis and extracellular matrix component production using two dimensional (2D) and three-dimensional (3D) culture models.

METHODS

Adipocyte size and index of fibrosis were determined on Sirius red-stained adipose tissue samples. Proliferating and adipocyte 2D-differentiating or 3D-differentiating ASCs were treated chronically with Tat or Nef. mRNA, protein expression and secretion were examined by RT-PCR, western-blot and ELISA.

RESULTS

SCAT and VAT from SIV-infected macaques displayed small adipocytes, decreased adipogenesis and severe fibrosis with collagen deposition. SCAT and VAT from HIV-infected ART-controlled patients presented similar alterations. In vitro, Tat and/or Nef induced a profibrotic phenotype in undifferentiated ASCs and altered adipogenesis and collagen production in adipocyte-differentiating ASCs.

CONCLUSION

We demonstrate here a specific role for HIV/SIV infection per se on adipose tissue fibrosis and adipogenesis, probably through the release of viral proteins, which could be involved in adipose tissue dysfunction contributing to cardiometabolic alterations of HIV-infected individuals.

Endocrinological aspects of HIV infection

PURPOSE

Patients with human immunodeficiency virus (HIV) are living longer with effective antiretroviral therapies and are enjoying near normal life span. Therefore, they are encountering endocrine issues faced by the general population along with those specific to HIV infection. The purpose of this article is to review the common endocrine aspects of HIV infection, and the early detection and management strategies for these complications.

METHODS

Recent literature on HIV and endocrine disease was reviewed.

RESULTS

HIV can influence endocrine glands at several levels. Endocrine glandular function may be altered by the direct effect of HIV viral proteins, through generation of systemic and local cytokines and the inflammatory response and via glandular involvement with opportunistic infections and HIV-related malignancies. Endocrine disorders seen in people with HIV include metabolic issues related to obesity such as diabetes, hyperlipidemia, lipohypertrophy, lipoatrophy and lipodystrophy and contribute significantly to quality of life, morbidity and mortality. In addition, hypogonadism, osteopenia and osteoporosis are also more prevalent in the patients with HIV. Although disorders of hypothalamic-pituitary-adrenal axis resulting in adrenal insufficiency can be life threatening, these along with thyroid dysfunction are being seen less commonly in the antiretroviral therapy (ART) era. ARTs have greatly improved life expectancy in people living with HIV but can also have adverse endocrine effects.

CONCLUSIONS

Clinicians need to have a high index of suspicion for endocrine abnormalities in people with HIV as they can be potentially life threatening if untreated. Endocrine evaluation should be pursued as in the general population, with focus on prevention, early detection and treatment to improve quality of life and longevity.

The Fat of the Matter: Obesity and Visceral Adiposity in Treated HIV Infection

PURPOSE OF REVIEW

The aim of this review is to summarize knowledge of the prevalence, relevant physiology, and consequences of obesity and visceral adiposity in HIV-infected adults, including highlighting gaps in current knowledge and future research directions.

RECENT FINDINGS

Similar to the general population, obesity prevalence is increasing among HIV-infected persons, and obesity and visceral adiposity are associated with numerous metabolic and inflammatory sequelae. However, HIV- and antiretroviral therapy (ART)-specific factors may contribute to fat gain and fat quality in treated HIV infection, particularly to the development of visceral adiposity, and sex differences may exist. Obesity and visceral adiposity commonly occur in HIV-infected persons and have significant implications for morbidity and mortality. Future research should aim to better elucidate the HIV- and ART-specific contributors to obesity and visceral adiposity in treated HIV infection, with the goal of developing targeted therapies for the prevention and treatment of obesity and visceral adiposity in the modern ART era.

Practical Review of Recognition and Management of Obesity and Lipohypertrophy in Human Immunodeficiency Virus Infection

Background

Obesity and lipohypertrophy are common in treated human immunodeficiency virus (HIV) infection and contribute to morbidity and mortality among HIV-infected adults on antiretroviral therapy (ART).

Methods

We present a consensus opinion on the diagnosis, clinical consequences, and treatment of excess adiposity in adults with treated HIV infection.

Results

Obesity and lipohypertrophy commonly occur among HIV-infected adults on ART and may have overlapping pathophysiologies and/or synergistic metabolic consequences. Traditional, HIV-specific, and ART-specific risk factors all contribute. The metabolic and inflammatory consequences of excess adiposity are critical drivers of non-AIDS events in this population. Although promising treatment strategies exist, further research is needed to better understand the pathophysiology and optimal treatment of obesity and lipohypertrophy in the modern ART era.

Conclusions

Both generalized obesity and lipohypertrophy are prevalent among HIV-infected persons on ART. Aggressive diagnosis and management are key to the prevention and treatment of end-organ disease in this population and critical to the present and future health of HIV-infected persons.

Differential relationships of hepatic and epicardial fat to body composition in HIV

HIV-infected patients commonly experience changes in central and peripheral fat content as well as ectopic fat accumulation. However, whether hepatic and epicardial fat stores relate differentially to body composition or how these associations are modified by HIV status has not been well explored. A previously recruited sample of 124 HIV-infected patients and 58 healthy controls had undergone dual energy X-ray absorptiometry (DEXA) and computed tomography (CT) from which body composition measures, liver-spleen ratio, and epicardial fat volume were obtained. Unique to the HIV-infected group, there was a parabolic association between abdominal subcutaneous adipose tissue (SAT) area and liver-spleen ratio (P = 0.03, inflection point 324 cm²) such that hepatic fat content was greatest at the extremes of low and high SAT A quadratic model also closely described the relationship between mean leg fat and liver-spleen ratio among patients with HIV (P = 0.02, inflection point 4.7 kg), again suggesting greater liver fat content with both low and high leg fat. Notably, an analogous relationship of epicardial fat with SAT was not evident among HIV-infected individuals or healthy controls. In contrast, visceral adipose tissue (VAT) linearly related to both liver-spleen ratio in HIV and epicardial fat volume irrespective of HIV status in multivariable models. In conclusion, our analyses implicate both low and high SAT as risk factors for hepatic fat accumulation in HIV These findings add to growing evidence of SAT dysfunction in the setting of HIV infection, and highlight key physiologic differences between hepatic and epicardial fat depots.

Human Leukocyte Antigen (HLA) and Immune Regulation: How Do Classical and Non-Classical HLA Alleles Modulate Immune Response to Human Immunodeficiency Virus and Hepatitis C Virus Infections?

The genetic factors associated with susceptibility or resistance to viral infections are likely to involve a sophisticated array of immune response. These genetic elements may modulate other biological factors that account for significant influence on the gene expression and/or protein function in the host. Among them, the role of the major histocompatibility complex in viral pathogenesis in particular human immunodeficiency virus (HIV) and hepatitis C virus (HCV), is very well documented. We, recently, added a novel insight into the field by identifying the molecular mechanism associated with the protective role of human leukocyte antigen (HLA)-B27/B57 CD8⁺ T cells in the context of HIV-1 infection and why these alleles act as a double-edged sword protecting against viral infections but predisposing the host to autoimmune diseases. The focus of this review will be reexamining the role of classical and non-classical HLA alleles, including class Ia (HLA-A, -B, -C), class Ib (HLA-E, -F, -G, -H), and class II (HLA-DR, -DQ, -DM, and -DP) in immune regulation and viral pathogenesis (e.g., HIV and HCV). To our knowledge, this is the very first review of its kind to comprehensively analyze the role of these molecules in immune regulation associated with chronic viral infections.

Fat Matters: Understanding the Role of Adipose Tissue in Health in HIV Infection

More than one-third of adults in the USA are obese and obesity-related disease accounts for some of the leading causes of preventable death. Mid-life obesity may be a strong predictor of physical function impairment later in life regardless of body mass index (BMI) in older age, highlighting the benefits of obesity prevention on health throughout the lifespan. Adipose tissue disturbances including lipodystrophy and obesity are prevalent in the setting of treated and untreated HIV infection. This article will review current knowledge on fat disturbances in HIV-infected persons, including therapeutic options and future directions.

Relationship between HHV8 infection markers and insulin sensitivity in ketosis-prone diabetes

BACKGROUND AND OBJECTIVES

Peripheral tissue resistance to insulin action is a characteristic of type 2 diabetes mellitus (T2DM). It has also been reported that some chronic viral infections can contribute to insulin resistance. Human herpesvirus (HHV)-8 infection has been detected in T2DM patients in previous studies. Our study investigated whether the presence of the virus is associated with insulin resistance in patients with ketosis-prone type 2 diabetes (KPD), as reported with other viruses.

RESEARCH DESIGN AND METHODS

A total of 11 insulin-free KPD patients positive (+) and seven patients who were negative (-) for HHV-8 infection were recruited; the latter had KPD that was well controlled (HbA_1c=6.2±0.7%). A two-step euglycaemic-hyperinsulinaemic clamp test coupled with deuterated [6,6-2H2]glucose was used to assess insulin sensitivity, non-esterified fatty acid (NEFA) suppression and endogenous glucose production.

RESULTS

In KPD patients, whether HHV-8+ or HHV-8-, there were no differences in NEFA release, endogenous glucose production or insulin sensitivity (M value).

CONCLUSION

Asymptomatic HHV-8 infection does not appear to be associated with decreased insulin sensitivity in diabetic patients. These results should now be confirmed in a larger sample population.