Ovariectomy Increases Pancreatic Endoplasmic Reticulum Stress Genes in Simian Immunodeficiency Virus Infection

Abstract

Background Antiretroviral therapy (ART) has significantly reduced mortality of people living with HIV (PLWH). Older PLWH, especially menopausal women, experience complex interactions of HIV, ART, hormonal status, and lifestyle behaviors such as at-risk alcohol use, increasing the risk of metabolic comorbidities. Our studies have demonstrated that chronic binge alcohol (CBA) significantly decreases acute insulin response to a glucose challenge in Simian Immunodeficiency Virus (SIV)-infected macaques, suggesting pathophysiological changes in pancreatic endocrine function. Endoplasmic Reticulum (ER) stress is one of the major mechanisms associated with alcoholic pancreatitis and endocrine pancreatic dysfunction. The objective of this study was to examine the effects of CBA administration and gonadal hormone loss, resulting from ovariectomy (OVX), on pancreatic mechanisms that contribute to impaired glucose-insulin dynamics in SIV-infected female macaques. Hypothesis Chronic binge alcohol and ovariectomy increase pancreatic ER stress and decrease expression of regulators of insulin synthesis. Methods CBA or isovolumetric water (VEH) was administered through an intragastric catheter for 30 minutes, 5 days a week. 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 and euthanized 9 months post-SIV-infection. Total RNA was isolated from pancreas collected from macaques (VEH/SHAM= 8, CBA/SHAM= 7, VEH/OVX= 7, CBA/OVX n=7). cDNA was synthesized and qPCR was used to analyze gene expression of markers for ER stress (X-Box Binding Protein 1, XBP1; Activating Transcription Factor 4, ATF4; and C/EBP Homologous Protein, CHOP) and regulators of insulin synthesis (Homeobox Protein Nkx-2.2, NKX2.2; insulin promoter factor 1, PDX1; Transcription factor MafA, MAFA; Glucose transporter 2, GLUT2; and Glucokinase). Results There was a main effect of OVX to increase mRNA expression of ATF4 and XBP1 (p<0.05) in SIV-infected macaques. There was not a statistically significant effect of CBA or OVX to alter gene expression of CHOP, or insulin synthesis markers, NKX2.2, PDX1, MAFA, GLUT2 and Glucokinase. Conclusions OVX increased pancreatic expression of ER stress markers without significantly altering expression of regulators of insulin synthesis. We speculate that the increased expression of ER stress markers may result in increased beta cell apoptosis. These findings provide evidence for pancreatic mechanisms that can contribute to the observed impairment of glucose insulin dynamics in SIV infection.