Decreased Toll-like Receptor (TLR) 2 and 4 Expression in Spermatozoa in Couples with Unexplained Recurrent Spontaneous Abortion (URSA)

Studies have shown that toll-like receptors (TLRs) play some important roles in reproductive processes such as ovulation, spermatogenesis, sperm capacitation, fertilization, and pregnancy to the best of our knowledge, no study has evaluated the expression and role of these molecules and their impairment in spermatozoa; accompanied by pregnancy complications such as recurrent spontaneous abortion (RSA). Therefore, this study investigates the alteration of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) expression in spermatozoa in men whose spouse have unexplained RSA. Fifteen fertile couples and fifteen couples with unexplained recurrent spontaneous abortion (URSA) were included in this study. The level of TLR2 and TLR4 expression in untreated and lipopolysaccharide (LPS) or PAM3CYS in treated spermatozoa were examined by flow cytometry. The results showed reduced expression of TLR4 in untreated spermatozoa and decreased LPS or PAM3CYS levels in treated spermatozoa in the URSA group compared to the control group. No significant differences were found in TLR2 expression of untreated spermatozoa in RSA and control groups. After the treatment of spermatozoa with LPS, the TLR2 expression was decreased in both groups. After the treatment of spermatozoa with PAM3CYS, the level of TLR2 expression was significantly increased in the URSA group; while no significant differences were shown in the control group in comparison to untreated spermatozoa. We have concluded that decreased TLR4 expression and a differently increased TLR2 expression in response to ligand treatment in spermatozoa is associated with URSA.