Differential Effects of Chronic Binge Alcohol and Ovariectomy on Apoptosis in Omental Adipose Tissue of SIV‐infected Macaques

Abstract

Adipose tissue maladaptations including cell death, inflammation, adipokine disruption, dysfunction of adipocytes and adipose tissue metabolism are central to metabolic alterations in HIV, at-risk alcohol use, and aging. Though adipose tissue dysregulation is a well-accepted mechanism meditating metabolic comorbidities in HIV, the effects of alcohol use and estrogen loss on adipose tissue cell death are not fully understood. Using a relevant preclinical model of HIV-infection, the aim of our study was to investigate the differential effects of chronic binge alcohol (CBA) administration and ovarian hormone loss, simulated by ovariectomy (OVX), on alterations in omental adipose tissue (OmAT) expression of genes involved in cell death. CBA or isovolumetric water (VEH) was administered through an intragastric catheter at a concentration of 30% (w/v) for 30 minutes, 5 days a week, with blood alcohol concentrations reaching 50-60 mM. Three months after initiation of CBA/VEH administration, macaques were infected with SIVMac251 and 2.5 months later initiated on ART. After 1 month of ART, macaques underwent sham surgery or ovariectomy. Unbiased quantitative proteomic analysis of OmAT revealed that proteins implicated in the apoptotic pathway were differentially regulated by CBA, OVX and the combination of both. Specifically, CBA and OVX independently led to proteome changes consistent with activation of apoptosis and necrosis pathways while the combination of CBA and OVX led to proteome changes consistent with inhibition of both apoptosis and necrosis. To confirm these results, OmAT expression of genes involved in apoptosis was determined using quantitative PCR. B-cell lymphoma 2 (BCL2), an antiapoptotic gene was increased by CBA but decreased in the CBA/OVX group. CBA increased the gene expression of BCL-2 homologous antagonist killer (BAK), a proapoptotic gene and increased the ratio of BCL2 associated X protein (BAX) to BCL2, an indicator of cell susceptibility to apoptosis. Our quantitative PCR results confirm and support the results of the OmAT proteomic analysis, suggesting that CBA and OVX differentially regulate the apoptotic pathway. However, in contrast to the results from the proteomic analysis, the preliminary gene expression data suggest that CBA is a major driver of apoptosis in the OmAT of female rhesus macaques. Our ongoing studies using TUNEL staining and analysis of crown-like structures will determine the effects of CBA and OVX on OmAT cell death. Additionally, the functional effects of CBA and OVX on adipose-derived stem cell death will be determined using flow cytometry.