(063) The Role of Leptin as a Testicular Immune Microenvironment Modulator and Leydig Stem Cell Function.

Introduction: The testicular microenvironment, consisting of cells including Sertoli and peritubular cells, releases paracrine factors that may regulate testicular function. In previous research, Leptin was identified as a critical paracrine factor in the testicular microenvironment. Leptin is secreted by Sertoli and peritubular cells and binds to its receptor in Leydig cells. This interaction triggers the expression of the desert hedgehog signaling pathway, which is essential for Leydig stem cell differentiation into adult Leydig cells, which are capable of producing testosterone. However, our earlier study had a limitation: the human cell model used was derived from testes biopsies, lacking an intact immune microenvironment. This study investigates the effect of Leptin on a complete testicular immune microenvironment in a murine model. Objective: To investigate the impact of Leptin on a complete testicular immune microenvironment. Methods: We used 6-week-old C57BL6 mice, exposed to two different concentrations of Leptin, 10 and 100 mg/ml, for seven days. After the treatment period, the animals were humanely euthanized, and their blood and testes were collected. Blood samples underwent a complete blood count differential profile analysis using a Hemavet Mascot Multispecies Hematology System Counter 1500R. Testes samples were subjected to comprehensive immunophenotyping, allowing us to assess the impact of Leptin treatment on various immune cell types within the testes Results: Leptin at a low dose (10 mg/ml) showed increased, but not significant, levels of serum testosterone (13.20 + 0.37 ng/dl), while LH and FSH levels significantly (p<0.05) increased. In contrast, animals receiving 100 mg/ml Leptin showed no significant changes in hormone levels. CBC profiling indicated that lymphocytes and platelets were significantly influenced, specifically with low doses of Leptin. Comprehensive immunophenotyping revealed a significant increase in CD4+ (helper T cells) and CD8+ (cytotoxic T lymphocytes) cell numbers in animals treated with low doses of Leptin, a pattern not observed with high doses. Conclusions: This study uncovers previously unexplored aspects of how paracrine factors, released by Sertoli and peritubular myoid cells, can modulate the immune microenvironment within the testis, potentially impacting testosterone production. Future research will investigate the relationship between changes in immune cell types, increased T cell numbers, and their influence on Leydig stem cell differentiation into adult Leydig cells Disclosure: No. [ABSTRACT FROM AUTHOR]