Title: Evaluation of sperm immobilization factor from Staphylococcus aureus as a potential candidate for male contraception
Abstract:
Despite considerable advances in female contraceptive options, male contraception remains limited to vasectomy and condoms, placing the primary contraceptive responsibility on women. Consequently, developing a safe, effective, and reversible contraceptive method for men is crucial. Amongst the various approaches, microbial derived products are gaining scientific interest to combat unintended pregnancies. Previously, our laboratory demonstrated that Sperm Immobilization Factor (SIF) isolated from Staphylococcus aureus effectively induced contraception in female mice, prompting investigation of its potential as male contraceptive. To explore this, male BALB/c mice were administered a single dose of SIF, at varying concentrations (10, 50, 100, or 200 µg) to the right testis only (test) while the left testis served as control. Mice were sacrificed on day 3, 7, 14, 21, 30, 45, 60, and 90. Across all time points, body weight and % TSI showed no significant change. When the seminal parameters were evaluated, azoospermia was observed up to day 90 at 200µg of SIF. However, in the left side normal seminal parameters were observed throughout the period of study. The histological examination revealed hypospermatogenesis and disruption of seminiferous tubules in right testis and empty epididymal tubules in the right cauda epididymis while the left testis and cauda epididymis showed normal tissue histology. The vas deferens of both sides showed normal histology. Lipid peroxidation when assessed by measuring MDA levels in tissue homogenates of testes on day 3 and 7, revealed significant increase in right testis compared to left testis. Further, effects of SIF on general health and metabolism in mice were assessed on day 90 through haematological parameters and serum levels of ALT and AST, where mice administered with single dose of 200 µg of SIF in right testis served as test group, and those administered with PBS in right testis served as control group. The parameters were found to be within the normal range, comparable to control group. A significant decrease in serum testosterone level was observed in SIF-administered mice as compared to control. Further, estimation of TNF-α and IL-10 levels in homogenates of right testis was determined on day 0, 1, 2, 3 and 4, and significant increase, peaking on day 1 for TNF-α and day 2 for IL-10 was detected, as compared to control. Further, to check the prolonged contraceptive efficacy of SIF, nanoparticles (NPs) were formulated using PLGA, ethyl acetate, and Poloxamer 407. In-vitro % SIF release demonstrated the burst release within 8h. In-vivo studies of SIF-loaded NPs (200 μg)/ blank NPs, instilled as single dose via intra-testis route in male mice were carried out and azoospermia was observed to be sustained up to day 120 in SIF-loaded NPs treated group, whereas blank NPs group showed no azoospermia and alterations in seminal parameters. Histological analysis confirmed azoospermia and empty caudal tubules in right testis and epididymis of SIF-NP-treated mice, with normal histology in blank-NP-treated mice. Henceforth, SIF and SIF loaded NPs with antifertility effect and being safe appear to be a promising alternative in the field of male contraceptives.
