Brief Report: Circulating Markers of Immunologic Activity Reflect Adiposity in Persons With HIV on Antiretroviral Therapy

Obesity in HIV infection: host-pathogen interaction

OBJECTIVE

Both obesity and HIV infection are characterized by a state of chronic inflammation associated with increased morbidity and mortality. This review aims to assess the available literature on immune dysregulation in obesity and people with HIV infection (PWH).

DESIGN

A systematic review of peer-reviewed literature.

METHODS

We conducted a systematic literature search of PubMed, Embase, Scopus, and international conference abstracts for articles on the epidemiology of obesity in the general population and in PWH and the pathogenesis of obesity with a focus on inflammation and immune activation.

RESULTS

Of the 631 articles selected after title review, 490 met the inclusion criteria and 90 were included in the final selection. The selected studies highlight the increasing prevalence of obesity in PWH and a substantial role for antiretroviral treatment (ART) in its development. Pathogenesis of obesity and its associated inflammation derives from disturbances in adipose tissue (AT) immune function, focused on T-cell and macrophage function, with a switch to pro-inflammatory immune phenotype and resulting increases in pro-inflammatory chemokines, which contribute to the development of metabolic syndrome. Although dysregulation of these pathways is seen in both obesity and HIV, there remains a lack of human studies on AT inflammation in HIV.

CONCLUSION

Obesity is an emerging comorbidity in PWH, with a substantial overlap in immune dysregulation patterns seen in both conditions. How this immune dysfunction impacts on development of metabolic complications for both obesity and HIV infection, and whether targeting of AT-derived inflammation will improve outcomes in PWH requires further study.

Normal weight obesity is associated with hypercholesterolemia and low muscle mass in persons living with HIV on antiretroviral treatment

OBJECTIVES

Normal weight obesity (NWO) is defined as a condition of normal body weight, but with high body fat percentage. Clinical and immunologic implications of NWO in persons living with HIV (PLHIV) remain unknown. The aim of this study was to examine NWO prevalence and its associations with metabolic and immunologic measurements in a cohort of PLHIV on antiretroviral treatment (ART).

METHODS

We enrolled 73 adult PLHIV on ART. Body composition was assessed by dual-energy x-ray absorptiometry. NWO was defined as body mass index 18.5 to 24.9 kg/m² and body fat ≥25%. We determined triacylglycerols, total cholesterol, high-density lipoprotein, low-density lipoprotein, blood glucose, blood pressure, bone mineral density, inflammatory cytokines (interleukin [IL]-1β, tumor necrosis factor-α and IL-6) and CD4+ and CD8+ T-cell activation.

RESULTS

The prevalence of NWO was 49% (36 of 73). Participants with NWO showed lower CD4+ T-cell percentage (25 versus 27%, P = 0.03), lower CD4/CD8 ratio (0.62 versus 0.82, P = 0.02), lower muscle mass (6.84 versus 7.11 kg/m², P = 0.01) and higher prevalence of hypercholesterolemia (26% versus 6%, P = 0.03) than individuals with normal body composition. No differences in inflammation/activation markers were observed between groups (P > 0.05 in all cases).

CONCLUSION

NWO was frequent in a cohort of Mexican PLHIV on ART and was associated with lower muscle mass, hypercholesterolemia, lower CD4+ T-cell percentage, and lower CD4/CD8 ratio. The incorporation of body fat measurements in the regular physical examination of PLHIV could contribute to early identification of the NWO condition and lead to better management of possible long-term morbidity.

The Association Between Weight Gain, Sex and Immune Activation Following the Initiation of Antiretroviral Therapy

BACKGROUND

Immune activation persists despite suppressive antiretroviral therapy (ART) and may be affected by sex or body composition. We explored these relationships in a subset of participants who initiated ART in two large randomized trials.

METHODS

Purposeful sampling selected participants who achieved virologic suppression on ART and either maintained weight within +/- 0.5 kg/m 2 or gained 2.6-6.4 kg/m 2 from baseline to 96 weeks. We measured 7 markers of inflammation and immune activation at weeks 0 and 96. Multivariable linear regression explored associations of weight gain, sex, and pre-ART BMI with pre-ART and changes in biomarker concentrations.

RESULTS

340 participants were selected; median pre-ART age 42 years, CD4+ cell count 273 cells/mm 3, HIV-1 RNA 4.7 log10 copies/mL; 49% were women, 33% white, 42% black, and 24% Hispanic. Among participants with a normal pre-ART BMI, higher pre-ART levels of IL-6, sTNF-RI and RII, CXCL-10, sCD163 and hsCRP were associated with weight gain. Association of weight gain with week 96 changes of these biomarkers differed by sex; women who gained weight had smaller declines in most measured biomarkers compared to men who gained.

CONCLUSIONS

Among women, weight gain is associated with attenuated decline in several immune activation markers following ART initiation.

Association of Male Sex and Obesity With Residual Plasma Human Immunodeficiency Virus 1 Viremia in Persons on Long-Term Antiretroviral Therapy

BACKGROUND

Although adipose tissue has been proposed to harbor part of the human immunodeficiency virus 1 (HIV-1) reservoir, the influence of host characteristics, including sex and body mass index (BMI), on measures of HIV-1 persistence during antiretroviral therapy (ART) are incompletely understood.

METHODS

We evaluated age, sex, BMI, waist circumference, years on ART, pre-ART HIV-1 RNA, pre-ART CD4+ T-cell count, and initial ART regimen with measures of HIV-1 persistence in blood (residual viremia, cellular HIV-1 DNA and RNA) in a cohort of 295 individuals with well-documented long-term virologic suppression (HIV-1 RNA <50 copies/mL) on ART (AIDS Clinical Trials Group study A5321).

RESULTS

Men were more likely than women to have detectable plasma HIV-1 RNA by single-copy assay (52% vs 29%; P = .003), and the proportion of participants with detectable residual viremia increased in a stepwise fashion by BMI category (normal weight or underweight, 38%; overweight, 50%; and obese, 55%). ART regimen type was not associated with measures of HIV-1 persistence after controlling for ART duration.

CONCLUSIONS

Sex and obesity are independently associated with residual viremia in people on long-term ART. Additional studies to confirm these relationships and to define the mechanisms by which sex and obesity affect HIV-1 persistence are needed to inform HIV-1 cure strategies.

Anticytomegalovirus CD4+ T Cells Are Associated With Subclinical Atherosclerosis in Persons With HIV

[Figure: see text].

Elevated Eosinophils as a Feature of Inflammation Associated With Hypertension in Virally Suppressed People Living With HIV

Background

People living with HIV (PLWH) are at increased risk of cardiovascular disease, including hypertension, which persists despite effective plasma viral suppression on antiretroviral therapy. HIV infection is characterized by long‐term alterations in immune function, but the contribution of immune factors to hypertension in PLWH is not fully understood. Prior studies have found that both innate and adaptive immune cell activation contributes to hypertension.

Methods and Results

We hypothesized that chronic inflammation may contribute to hypertension in PLWH. To test this hypothesis, we enrolled a cohort of 70 PLWH (44% hypertensive) on a long‐term single antiretroviral therapy regimen for broad phenotyping of inflammation biomarkers. We found that hypertensive PLWH had higher levels of inflammatory cytokines, including tumor necrosis factor‐α receptor 1, interleukin‐6, interleukin‐17, interleukin‐5, intercellular adhesion molecule 1 and macrophage inflammatory protein‐1α. After adjustment for age, sex, and fat mass index, the circulating eosinophils remained significantly associated with hypertension. On the basis of these results, we assessed the relationship of eosinophils and hypertension in 2 cohorts of 50 and 81 039 similar HIV‐negative people; although eosinophil count was associated with prevalent hypertension, this relationship was abrogated by body mass index.

Conclusions

These findings may represent a unique linkage between immune status and cardiovascular physiological characteristics in HIV infection, which should be evaluated further.

Examining Relationships between Metabolism and Persistent Inflammation in HIV Patients on Antiretroviral Therapy

With the advent of antiretroviral therapy (ART), HIV-infected individuals are now living longer and healthier lives. However, ART does not completely restore health and treated individuals are experiencing increased rates of noncommunicable diseases such as dyslipidemia, insulin resistance, type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease. While it is well known that persistent immune activation and inflammation contribute to the development of these comorbid diseases, the mechanisms underlying this chronic activation remain incompletely understood. In this review, we will discuss emerging evidence that suggests that alterations in cellular metabolism may play a central role in driving this immune dysfunction in HIV patients on ART.