Background Stress has emerged as an important risk factor for heart disease in women. Stress levels have been shown to correlate with delayed recovery and increased mortality after a myocardial infarction. Therefore, we sought to investigate if the observed sex‐specific effects of stress in myocardial infarction may be partly attributed to genomic interactions between the female sex hormones, estrogen (E2), and the primary stress hormones glucocorticoids. Methods and Results Genomewide studies show that glucocorticoids inhibit estrogen‐mediated regulation of genes with established roles in cardiomyocyte homeostasis. These include 5‐HT2BR (cardiac serotonin receptor 2B), the expression of which is critical to prevent cardiomyocyte death in the adult heart. Using siRNA, gene expression, and chromatin immunoprecipitation assays, we found that 5‐HT2BR is a primary target of the glucocorticoid receptor and the estrogen receptor α at the level of transcription. The glucocorticoid receptor blocks the recruitment of estrogen receptor α to the promoter of the 5‐HT2BR gene, which may contribute to the adverse effects of stress in the heart of premenopausal women. Using immunoblotting, TUNEL (terminal deoxynucleotidal transferase–mediated biotin–deoxyuridine triphosphate nick‐end labeling), and flow cytometry, we demonstrate that estrogen decreases cardiomyocyte death by a mechanism relying on 5‐HT2BR expression. In vitro and in vivo experiments show that glucocorticoids inhibit estrogen cardioprotection in response to hypoxia/reoxygenation injury and exacerbate the size of the infarct areas in myocardial infarction. Conclusions These results established a novel mechanism underlying the deleterious effects of stress on female cardiac health in the setting of ischemia/reperfusion.

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent forms of chronic liver disease in the United States and worldwide. Non-alcoholic steatohepatitis (NASH), the most advanced form of NAFLD, is characterized by hepatic steatosis associated with inflammation and hepatocyte death. No treatments are currently available for NASH other than lifestyle changes, and the disease lacks specific biomarkers. The signaling lymphocytic activation molecule 1 (SLAMF1) protein is a self-ligand receptor that plays a role in orchestrating an immune response to some pathogens and cancers. We found that livers from humans and mice with NASH showed a more prominent immunohistochemistry staining for SLAMF1 than non-NASH controls. Furthermore, SLAMF1 levels are significantly increased in NASH plasma samples from mice and humans compared to their respective controls. In mice, the levels of SLAMF1 correlated significantly with the severity of the NASH phenotype. To test whether SLAMF 1 is expressed by hepatocytes, HepG2 cells and primary murine hepatocytes were treated with palmitic acid (PA) to induce a state of lipotoxicity mimicking NASH. We found that PA treatments of HepG2 cells and primary hepatocytes lead to significant increases in SLAMF1 levels. The downregulation of SLAMF1 in HepG2 cells improved the cell viability and reduced cytotoxicity. The in vivo data using mouse and human NASH samples suggests a potential role for this protein as a non-invasive biomarker for NASH. The in vitro data suggest a role for SLAMF1 as a potential therapeutic target to prevent hepatocyte death in response to lipotoxicity.

The signaling lymphocytic activation molecule 1 (SLAMF1) exerts a role in regulating the immune response to some viruses and parasite infections. In the present study, we identified SLAMF1 as a potential therapeutic target and biomarker for Non-Alcoholic Fatty Liver Disease (NASH) in humans. We found that SLAMF1 is highly expressed in liver samples from mice and humans with NASH. Our data also show SLAMF1 is detected in plasma, and its levels correlate with the severity of the disease. To uncover a molecular role for SLAMF1 in hepatocytes, we treated two hepatocyte cell lines (HepG2 and HuH-7) and primary mouse hepatocyte with palmitic acid (PA) to induce lipotoxicity, characteristic of NASH. We found that PA treatment leads to a significant increase in SLAMF1 protein levels in the cell lines and primary hepatocytes. We found an increase in HepG2 cell apoptosis in response to PA treatment, and downregulation of SLAMF1 in hepatocytes with siRNA improved cell viability and reduced cytotoxicity, apoptosis, and the expression of inflammatory mediators. Moreover, we found that PA-treated HepG2 cells secrete SLAMF1 in the culture medium, which may be mediating part of these effects through paracrine action. Our findings suggest a role for SLAMF1 in NASH's pathogenesis and highlight SLAMF1 as a reliable clinical biomarker of the disease. Presentation: Saturday, June 11, 2022 12:00 p.m. - 12:15 p.m.

Mental stress is a risk factor for myocardial infarction in women. The central hypothesis of this study is that restraint stress induces sex-specific changes in gene expression in the heart, which leads to an intensified response to ischemia/reperfusion injury due to the development of a pro-oxidative environment in female hearts. We challenged male and female C57BL/6 mice in a restraint stress model to mimic the effects of mental stress. Exposure to restraint stress led to sex differences in the expression of genes involved in cardiac hypertrophy, inflammation, and iron-dependent cell death (ferroptosis). Among those genes, we identified tumor protein p53 and cyclin-dependent kinase inhibitor 1A (p21), which have established controversial roles in ferroptosis. The exacerbated response to I/R injury in restraint-stressed females correlated with downregulation of p53 and nuclear factor erythroid 2–related factor 2 (Nrf2, a master regulator of the antioxidant response system-ARE). S-female hearts also showed increased superoxide levels, lipid peroxidation, and prostaglandin-endoperoxide synthase 2 (Ptgs2) expression (a hallmark of ferroptosis) compared with those of their male counterparts. Our study is the first to test the sex-specific impact of restraint stress on the heart in the setting of I/R and its outcome.

While clinical evidence indicates that exposure to mental stress is a linked to a two-fold increased risk for coronary heart disease, even independently from traditional risk factors, the underlying direct mechanisms between psychological stress and cardiovascular health status has not been determined. A growing aging population of adults 65 and older represents a particular patient population vulnerable to chronic mental stressors due to a decline in normal physiologic functions. The decrease in function of the cardiovascular system that occurs during aging leads to the activation of pathological processes associated with an increased risk for heart disease. Using a mouse model of mental stress induced by restraint, we mimic the biochemical and physiologic changes observed in chronically stressed humans, which is characterized by an increase in circulating glucocorticoids, such as cortisol. Middle-aged mice (6 months old) as well as old-aged mice (18 months old) were used to differentiate the effects of aging on the burden of mental stress associated cardiovascular disease. Genes implicated in cardiomyopathy and CVD were found to be significantly up-regulated, not only immediately after a two-week stress period, but remained significantly up-regulated after the mice were allowed to recover stress-free for 5 weeks. Gene expression of the glucocorticoid receptor was down-regulated following exposure to chronic stress, suggesting an involvement of the hypothalamic-pituitary axis negative feedback loop. Gene expression of markers for hypertrophy (MHY7, ACTA1, NPPB) were upregulated and persisted in upregulation after mice were allowed to recover. Hypertrophy was further indicated by heart weight to tibia length ratios. Significant changes in aortic samples also implicate an involvement of the vasculature. Chronic stress in humans and mice leads to an increase in inflammatory and pro-coagulant markers. In our study, inflammatory markers (LCN, IL-6, IL-17c, PTGS2) were shown to be significantly increased immediately after the period of chronic stress, however the markers return to non-significant levels when mice were allowed a recovery period. Chronic mental stress has a lasting and direct deleterious effect on the cardiovascular system and it is essential to understand these implications in an aging population.