Abnormal immune activation and fibrosis of epicardial adipose tissue in people living with HIV: results from the PIECVIH study

Background

Increased Epicardial Adipose Tissue (EAT) volume has been associated with increased risk of CAD in people living with HIV (PLWH). However, the underlying mechanisms remain unknown.

Purpose

We conducted the PIECVIH study to compare EAT properties in relation with CAD between PLWH and HIV-negative patients, all undergoing coronary artery bypass graft (CABG).

Methods

The PIECVIH study is a cross sectional prospective study performed in a single center enrolling 11 ART-controlled PLWH and 11 matched (age ± 3 years and sex) HIV-negative patients requiring CABG. During surgery, EAT and thoracic subcutaneous fat samples were taken. Gene expression was analyzed in samples with sufficient mRNA quality (7 PLWH and 7 HIV− for subcutaneous fat, 9 PLWH and 8 HIV− samples for EAT). The expression of 30 genes, mainly related to inflammation, immune activation, fibrosis and adipokines, was evaluated and related to the expression of the reference gene 18S.

Results

The mean age of the cohort was 59.8 years (100% male). The cardiovascular risk profile was quite similar between both groups including 66% smokers, 64% hypercholesterolemia, 36% hypertriglyceridemia and 56% hypertension. However, HIV− subjects had a higher prevalence of diabetes (73% vs 18%, p=0.002) and a higher body mass index than HIV− (23,2 vs 27.5 kg/m2, p=0.017). The level of gene expression of all tested genes was not different between PLWH and HIV− subjects in subcutaneous fat. Conversely, in EAT, the relative expression of IL-6 and CCL2 was 3–5-fold higher in samples issued from PLWH than from HIV−: respectively 0.46 vs 0.13 (p=0.03) and 1.13 vs 0.24 (p=0.03). Moreover, only in EAT, and only in PLWH, the expression of the chemokines CCL2 and CCL5 and of the macrophage immune activation markers (CD68, CD163, CD206), was globally related to the expression of genes involved into fibrosis: collagen genes (COL1A1, COL3A1, COL3A1, COL6A2, COL6A3), TGFB, LOX (lysyl-oxidase) and ASAH1 (acid ceraminidase). Only in EAT and only in PLWH, the expression of IGF1 and CES (carboxylesterase 1), two genes associated with increased cardiovascular risk, was related to the expression of genes associated with immune activation, fibrosis and vascularization (VEGFA). Only in PLWH, the Gensini score, evaluating the severity of CAD, was associated with EAT expression of collagen 6 and of the CV risk factors IGF1 and CES.

Conclusion

In very high CV risk subjects undergoing CABG, inflammation/immune activation of EAT was higher in PLWH as compared to controls. In EAT of PLWH, immune activation was strongly associated with fibrosis stressing for a dysfunctional EAT. Moreover, the severity of CAD, as addressed by the Gensini score, was associated with collagen 6 expression, a deleterious collagen in the context of EAT fibrosis. We propose that in PLWH, altered EAT immune profile and fibrosis could be responsible for reported accelerated CAD.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): French Agency for Research on AIDS and Viral Hepatitis

Comparison of HIV-Infected and Noninfected Patients Undergoing Bariatric Surgery: The ObeVIH Study

OBJECTIVE

The aim of this study was to compare clinical characteristics and adipose/liver tissue histology analysis in HIV-infected and HIV-uninfected subjects undergoing bariatric surgery.

DESIGN

This was a cross-sectional study of HIV-infected subjects undergoing single-port sleeve gastrectomy with prospective enrolment and frequency age (±5 years), sex, and body mass index (BMI, ± 5 kg/m2) matched on HIV-uninfected subjects.

METHODS

This study was conducted at a single clinical site at Pitié-Salpêtrière hospital-Paris-France comprising 19 HIV-uninfected and 21 HIV-infected subjects with plasma VL < 20 copies/mL, all with a BMI > 40 kg/m2 or >35 kg/m2 with comorbidities. Histology of subcutaneous and visceral abdominal adipose tissue (SCAT/VAT) and liver biopsies was collected during single-port sleeve gastrectomy. Outcomes included anthropometric characteristics, comorbidities, cardiovascular parameters, adipose tissue, and liver histology.

RESULTS

The age of HIV-infected participants was (median, interquartile range IQR) 48 y (42-51), with 76.2% females, a BMI of 41.4 kg/m2 (37.3-44.4), an antiretroviral duration of 16 y (8-21), current integrase strand transfer inhibitor (INSTI)-based regimen in 15 participants and non-INSTI regimen in 6 participants, and a CD4 count of 864/mm3 (560-1066). The age of controls was 43 y (37-51), with 78.9% females and a BMI of 39.2 kg/m2 (36.3-42.6). Anthropometric characteristics, comorbidities, and cardiovascular parameters did not differ according to HIV status and INSTI treatment. The number of macrophage crown-like structures in SCAT was lower in INSTI-treated participants than in HIV-uninfected participants (P = 0.02) and non-INSTI-treated HIV-infected subjects (P = 0.07). Hepatic steatosis and liver disease severity global score were lower in INSTI-treated participants than in non-INSTI-treated HIV-infected participants (P = 0.05 and P = 0.04, respectively).

CONCLUSIONS

HIV-infected and HIV-uninfected subjects undergoing bariatric surgery presented a similar profile regarding anthropometric measures, cardiovascular parameters, and comorbidities. However, INSTI-treated participants presented milder SCAT and liver alterations than non-INSTI-treated participants.

Long-term treatment with interleukin-1beta induces insulin resistance in murine and human adipocytes

AIMS/HYPOTHESIS

Adipose tissue inflammation has recently been implicated in the pathogenesis of insulin resistance and is probably linked to high local levels of cytokines. IL1B, a proinflammatory cytokine, may participate in this alteration.

MATERIALS AND METHODS

We evaluated the chronic effect (1-10 days) of IL1B (0.1-20 ng/ml) on insulin signalling in differentiating 3T3-F442A and differentiated 3T3-L1 murine adipocytes and in human adipocytes. We also assessed expression of the gene encoding IL1B in adipose tissue of wild-type and insulin-resistant mice (diet-induced and genetically obese ob/ob mice).

RESULTS

IL1B inhibited insulin-induced phosphorylation of the insulin receptor beta subunit, insulin receptor substrate 1, Akt/protein kinase B and extracellular regulated kinase 1/2 in murine and human adipocytes. Accordingly, IL1B suppressed insulin-induced glucose transport and lipogenesis. Long-term treatment of adipose cells with IL1B decreased cellular lipid content. This could result from enhanced lipolysis and/or decreased expression of genes involved in lipid metabolism (acetyl-CoA carboxylase, fatty acid synthase). Down-regulation of peroxisome proliferating-activated receptor gamma and CCAAT/enhancer-binding protein alpha in response to IL1B may have contributed to the altered phenotype of IL1B-treated adipocytes. Moreover, IL1B altered adipocyte differentiation status in long-term cultures. IL1B also decreased the production of adiponectin, an adipocyte-specific protein that plays a positive role in insulin sensitivity. Expression of the gene encoding IL1B was increased in epididymal adipose tissue of obese insulin-resistant mice.

CONCLUSIONS/INTERPRETATION

IL1B is upregulated in adipose tissue of obese and insulin-resistant mouse models and may play an important role in the development of insulin resistance in murine and human adipose cells.