(251) Exogenous Leptin Treatment Augments Testicular T-cell Secretion and Function Differentially in Context to BMI in Murine Models

Abstract Introduction In previous research, we explored the effects of exogenous Leptin treatment on modulating the immune landscape within the testicular microenvironment (TME). We found that within the TME, it is the CD8+ T cells which were enriched upon Leptin treatment. However, our earlier study did not took into account the impact of variations in BMI which could potentially confound the effects of Leptin on T cells and on TME as a whole. Objective To investigate the impact of Leptin on a complete testicular immune microenvironment. Methods We used 6-week-old C57BL6 mice (n=30), grouped into three, with first group subjected to regular diet, second to Lean fat and third to high fat inducing diet. Once the mice reached the desired weights, they were 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 CBC 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 In mice with regular BMI, 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 upon 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. These results were in contrast to the mice which represented lean and obese conditions. Conclusions This study uncovers previously unexplored aspects of how exogenous Leptin treatments 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.