Involvement of sperm plasma membrane and cytoskeletal proteins in human male infertility.

OBJECTIVE To assess the physicochemical characteristics of sperm plasma membrane and to evaluate the immunohistochemical expression of transmembrane and cytoskeletal proteins in spermatozoa isolated from normospermic fertile donors and asthenozoospermic infertile patients. DESIGN Case-control study. SETTING Academic male infertility center. PATIENT(S) Twenty-five infertile patients affected by idiopathic asthenozoospermia and 21 age-matched normospermic fertile donors. INTERVENTION(S) Sperm parameters were evaluated; membrane fluidity and hydration studies, and immunohistochemical analysis were performed in isolated spermatozoa. MAIN OUTCOME MEASURE(S) Semen analyses to ascertain volume, sperm count, motility, and morphology; then membrane fluidity and hydration studies and immunohistochemical analysis were performed on isolated spermatozoa. RESULT(S) Spermatozoa from the asthenozoospermic group exhibited a reduced fluidity at the lipid-water interface level, an increased fluidity of the deeper portion of the bilayer, and a lower plasma membrane hydration than normospermic cells. Moreover, the immunohistochemical expression of ezrin, Cdc42, CD9, F-actin, and β-tubulin was higher in normospermic samples. CONCLUSION(S) Our results together assume that a cytoskeletal reorganization induced by a disturbance in the physicochemical features of sperm plasma membrane, and potentially mediated by ezrin, Cdc42, and tetraspanin CD9, could have a role in idiopathic asthenozoospermia.