Greater IL-6, D-dimer, and ICAM-1 Levels Are Associated With Lower Small HDL Particle Concentration in the Multicenter AIDS Cohort Study

Inflammation in HIV and Its Impact on Atherosclerotic Cardiovascular Disease

People living with HIV have a 1.5- to 2-fold increased risk of developing cardiovascular disease. Despite treatment with highly effective antiretroviral therapy, people living with HIV have chronic inflammation that makes them susceptible to multiple comorbidities. Several factors, including the HIV reservoir, coinfections, clonal hematopoiesis of indeterminate potential (CHIP), microbial translocation, and antiretroviral therapy, may contribute to the chronic state of inflammation. Within the innate immune system, macrophages harbor latent HIV and are among the prominent immune cells present in atheroma during the progression of atherosclerosis. They secrete inflammatory cytokines such as IL (interleukin)-6 and tumor necrosis-α that stimulate the expression of adhesion molecules on the endothelium. This leads to the recruitment of other immune cells, including cluster of differentiation (CD)8+ and CD4+ T cells, also present in early and late atheroma. As such, cells of the innate and adaptive immune systems contribute to both systemic inflammation and vascular inflammation. On a molecular level, HIV-1 primes the NLRP3 (NLR family pyrin domain containing 3) inflammasome, leading to an increased expression of IL-1β, which is important for cardiovascular outcomes. Moreover, activation of TLRs (toll-like receptors) by HIV, gut microbes, and substance abuse further activates the NLRP3 inflammasome pathway. Finally, HIV proteins such as Nef (negative regulatory factor) can inhibit cholesterol efflux in monocytes and macrophages through direct action on the cholesterol transporter ABCA1 (ATP-binding cassette transporter A1), which promotes the formation of foam cells and the progression of atherosclerotic plaque. Here, we summarize the stages of atherosclerosis in the context of HIV, highlighting the effects of HIV, coinfections, and antiretroviral therapy on cells of the innate and adaptive immune system and describe current and future interventions to reduce residual inflammation and improve cardiovascular outcomes among people living with HIV.

Low levels of small HDL particles predict but do not influence risk of sepsis

BACKGROUND

Low levels of high-density lipoprotein (HDL) cholesterol have been associated with higher rates and severity of infection. Alterations in inflammatory mediators and infection are associated with alterations in HDL cholesterol. It is unknown whether the association between HDL and infection is present for all particle sizes, and whether the observed associations are confounded by IL-6 signalling.

METHODS

In the UK Biobank, ~ 270,000 individuals have data on HDL subclasses derived from nuclear magnetic resonance analysis. We estimated the association of particle count of total HDL and HDL subclasses (small, medium, large, and extra-large HDL) with sepsis, sepsis-related death, and critical care admission in a Cox regression model. We subsequently utilised genetic data from UK Biobank and FinnGen to perform Mendelian randomisation (MR) of each HDL subclass and sepsis to test for a causal relationship. Finally, we explored the role of IL-6 signalling as a potential causal driver of changes in HDL subclasses.

RESULTS

In observational analyses, higher particle count of small HDL was associated with protection from sepsis (Hazard ratio, HR 0.80; 95% CI 0.74-0.86, p = 4 × 10-9 comparing Quartile 4, highest quartile of HDL to Quartile 1, lowest quartile of HDL), sepsis-related death (HR 0.80; 95% CI 0.74-0.86, p = 2 × 10-4), and critical care admission with sepsis (HR 0.72 95% CI 0.60-0.85, p = 2 × 10-4). Parallel associations with other HDL subclasses were likely driven by changes in the small HDL compartment. MR analyses did not strongly support causality of small HDL particle count on sepsis incidence (Odds ratio, OR 0.98; 95% CI 0.89-1.07, p = 0.6) or death (OR 0.94, 95% CI 0.75-1.17, p = 0.56), although the estimate on critical care admission with sepsis supported protection (OR 0.73, 95% CI 0.57-0.95, p = 0.02). Bidirectional MR analyses suggested that increased IL-6 signalling was associated with reductions in both small (beta on small HDL particle count - 0.16, 95% CI - 0.10 to - 0.21 per natural log change in SD-scaled CRP, p = 9 × 10-8).and total HDL particle count (beta - 0.13, 95% CI - 0.09 to - 0.17, p = 7 × 10-10), but that the reverse effect of HDL on IL-6 signalling was largely null.

CONCLUSIONS

Low number of small HDL particles are associated with increased hazard of sepsis, sepsis-related death, and sepsis-related critical care admission. However, genetic analyses did not strongly support this as causal. Instead, we demonstrate that increased IL-6 signalling, which is known to alter infection risk, could confound associations with reduced HDL particle count, and suggest this may explain part of the observed association between (small) HDL particle count and sepsis.

HIV and Global Cardiovascular Health

PURPOSE OF REVIEW

Because of effective combination antiretroviral therapy, people living with HIV (PLWH) are living longer but developing chronic age-related conditions including cardiovascular disease (CVD), the leading cause of death globally. This review aims to discuss the epidemiology, mechanisms, and clinical considerations of CVD in PLWH from a global perspective.

RECENT FINDINGS

PLWH are at greater risk for CVD at chronologically younger ages than those without HIV. Potential underlying mechanisms for CVD in PLWH include systemic inflammation, comorbidities, immune-mediated, or treatment-related mechanisms. There is also risk factor variation based on geographical location, including non-traditional CVD risk factors. CVD is prevalent in PLWH and increasing on a global scale. Further understanding the unique epidemiology, risk factors, and treatment of CVD in this population will improve the care of PLWH.

The Effect of protease inhibitors-based antiretroviral therapy on serum/plasma interleukin-6 levels among PLHIV: a systematic review and meta-analysis

INTRODUCTION

Recommended treatment regimen for HIV infection includes protease inhibitors/ritonavir (PIs/r) combined with two nucleoside reverse transcriptase inhibitors (2NRTIs), that enable to achieve and maintain viral suppression, restore and preserve immune function. However, there were inconsistent findings on the levels of interleukin-6 levels (IL-6).

METHODOLOGY

Systematic review and meta-analysis were performed to quantify the pooled effects of PIs/r-based ART on serum/plasma IL-6 levels in PLHIV. PubMed, Web of Science, and Embase were searched from the earliest record to November 4, 2020. Data analysis was conducted on Stata version 16 and Review Manager 5.3. A random-effect model was used to compute a pooled effect size and weighted mean difference (WMD) was considered the summary effect size. Heterogeneity between studies was estimated by Cochrane's Q test (chi-square test) and I-square statistic and subgroup analysis were performed to explore the source of heterogeneity.

RESULT

Initial search identified 3098 records and five studies (seven trials) met inclusion criteria. The pooled mean difference in serum/plasma IL-6 levels from baseline to follow-up was 0.534 pg/ml (95% CI: -0.012, 1.08, P=0.05, I² =76.4%). In subgroup analysis, there was a significant association between increased serum/plasma IL-6 levels, and age group ≥35 years old, baseline CD4⁺ counts <350 cell/mm³ , and mean viral load ≥ 4.5 log10 copies/ml.

CONCLUSION

We found that serum/plasma IL-6 levels increased after combined anti-retroviral therapy (cART) among treatment-naïve individuals who initiated a successful combination of PIs/r with 2NRTIs. This result also highlights the need to monitor serum/plasma IL-6 levels during antiviral therapy, which may aid in the effective future treatment of systemic inflammation and related disorders following elevated IL-6 levels. This article is protected by copyright. All rights reserved.

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.