7975 TLR4 Signaling Modulates Reproductive and Metabolic Outcomes in a Mouse Model of Polycystic Ovary Syndrome

Abstract Disclosure: K.D. Wiggins: None. Z. Del Mundo: None. J.A. Ayala Angulo: None. M. Lopez: None. C. Garcia: None. C. Nguyen: None. J. De La Torre: None. A. Saba: None. D. Trinh: None. D. Nicholas: None. Polycystic Ovarian Syndrome (PCOS), characterized by disruptions in both reproductive and metabolic functions, is associated with abnormal immune system activity and chronic inflammation. Although the precise mechanistic drivers of chronic inflammation in PCOS are not fully elucidated, elevated serum levels of lipopolysaccharide (LPS) have been observed. We propose that Toll-like receptor 4 (TLR4) signaling, influenced by dysregulated LPS levels, is a central driver of chronic inflammation affecting both reproductive and metabolic pathways. To investigate this hypothesis, we subcutaneously implanted a nonsteroidal aromatase inhibitor, Letrozole (LET), in pubertal TLR4 knockout mice (TLR4KO) and C57BL/6J (wild type) mice. Our five-week LET treatment revealed that TLR4KO mice successfully entered all phases of the estrous cycle, with normalized Luteinizing Hormone (LH) and increased Follicle Stimulating Hormone (FSH) levels. These findings highlight TLR4's role in shaping cycling patterns and regulating fundamental hormonal pathways vital for reproductive health. Despite the genetic manipulation of the inflammatory pathway leading to a reduction in overall body weight gain, it had no discernible impact on the overall body composition of fat and lean mass. Additionally, our study found that dysregulation of blood glucose levels over time was independent of reduced body weight. TLR4KO mice demonstrated inefficient glucose clearance compared to wild-type mice, hinting at potential increases in insulin resistance, imbalances in adipose tissue inflammation, or possible alterations in the gut microbiota. Our study underscores the significance of disrupting the pro-inflammatory TLR4 pathway in shaping the reproductive and metabolic phenotypes in Letrozole-induced PCOS. The investigation into TLR4 becomes pivotal for comprehending the role of chronic inflammation in PCOS development or progression, offering valuable insights into potential therapeutic targets. Presentation: 6/2/2024