A corollary study to substantiate the therapeutic role of receptor from Shigella flexneri in mitigating the sperm immobilization factor-mediated negative influences on mouse spermatozoa: a molecular mimicry-based approach.

Abstract

Context Sperm immobilization factor (SIF) isolated from Staphylococcus aureus has been implicated earlier in the laboratory in infertility due to its negative impact on sperm function. Moreover, SIF was found to bind not only to human and mouse spermatozoa but also to several bacteria. Among the array of bacteria, we selected Shigella flexneri to investigate if it shares antigenic determinants with spermatozoa. Aim The study aimed to delineate receptors from S. flexneri that imitate the sperm receptor in binding SIF, to assess its therapeutic role in SIF-mediated sperm impairment. Methods Sperm immobilization binding receptor (SBR) from S. flexneri (SF-SBR) was isolated via ultrasonication and 4M NaCl treatment, purified via chromatography and its molecular weight was estimated. The ability of SF-SBR to counteract SIF-induced sperm impairment was assessed in vitro . Further analysis included isothermal titration calorimetry and fourier-transform infrared spectroscopy to quantify the interaction of SIF and SF-SBR. Key results SF-SBR ameliorated the sperm parameters adversely affected by SIF. It also interfered with the binding of fluorescein isothiocyanate-labelled SIF to spermatozoa and bacteria. The SIF and SF-SBR interaction showed favourable thermodynamics with an entropy of 28.12J/molK and free energy of -18.48kJ/mol, supporting the concept of mimicry. Conclusions The study confirmed that SF-SBR shares an epitope with the receptor on mouse spermatozoa, affirming the presence of molecular mimicry between spermatozoa and S. flexneri . Implications These findings indicate that SF-SBR can potentially be used to counteract the effects of SIF on spermatozoa, hinting at novel therapeutic approaches for treating infertility caused by microbial sperm immobilization factors.