Proinflammatory cytokines as an intermediate factor enhancing lipid sperm membrane peroxidation in in vitro conditions

Abstract

We have examined the effect of white blood cells (WBCs), various proinflammatory cytokines, or a combination of the two on the peroxidation of human sperm membrane lipids in in vitro conditions. Six recombinant cytokines, such as interleukin-1β (IL-1β), IL-6, IL-8, IL-12, IL-18, and tumor necrosis factor alpha (TNF-α), used singly or in combinations, were analyzed. WBCs were isolated from the whole heparinized blood using a density gradient technique (Histopaque 1.077). Spermatozoa were isolated from semen samples with normal sperm parameters by both the swim-up technique (swim-up fraction) and by a discontinuous Percoll gradient centrifugation (90% and 47% Percoll fractions). Peroxidative damage to sperm membrane lipids was assessed by determining the concentration of malondialdehyde (MDA) in lysates of spermatozoa using high-performance liquid chromatography (HPLC). There were no statistically significant differences in MDA concentrations between sperm fractions incubated with cytokines and respective controls (spermatozoa alone). In spermatozoa isolated by the swim-up technique, the MDA level was significantly higher only after incubation with IL-6 and IL-8 plus WBCs when compared to sperm incubated with leukocytes alone (0.62 ± 0.21 μmol/L and 0.42 ± 0.22 μmol/L, respectively; P < .05). The results obtained suggest that cytokines produced during the inflammatory process intensify the level of oxidative stress caused by leukocytes, which may have serious consequences for sperm membrane integrity. Copyright © American Society of Andrology.