(HealthDay News) — Low levels of human β-defensin 1 (DEFB1) in sperm may explain some of the common causes of male infertility, according to research published in the August 13 issue of Science Translational Medicine.

Ruiying Diao, of the First Affiliated Hospital of Shenzhen University in China, and colleagues studied sperm and DEFB1 levels in men diagnosed with infertility caused by asthenozoospermia or leukocytospermia.

The researchers found low levels of DEFB1 in sperm from men with infertility caused by either asthenozoospermia or leukocytospermia, both of which are associated with reduced motility and reduced bactericidal activity in sperm. The same defects in sperm were observed when there was interference with DEFB1 function. Treatment with recombinant DEFB1 markedly restores DEFB1 expression, bactericidal activity, sperm quality, and egg-penetrating ability in sperm from men with asthenozoospermia or leukocytospermia. DEFB1 interacts with chemokine receptor type 6 (CCR6) in sperm and mobilizes Ca2+, which is involved in sperm motility. Interference with the function of CCR6 also reduces the motility and bactericidal activity of normal sperm.

“In closing, the demonstrated dual role of DEFB1 in defending male fertility and the involvement of DEFB1 and its interacting protein CCR6 in the pathogenesis of asthenozoospermia and leukocytospermia have suggested potential diagnostic targets and a feasible treatment method for male infertility associated with poor sperm motility and genital tract infection,” the authors write.

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