Aim: To investigate if interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interferon-gamma (IFN-) or tumor necrosis factor-alpha (TNF-) are able to stimulate the level of lipid peroxidation of sperm membranes, either alone or in the presence of leukocytes.

Methods: Semen samples from normozoospermic donors were prepared by density gradient. The sperms were exposed to the indicated cytokines, at physiological and infection-inflammation concentrations, in the absence or presence of leukocytes. Lipid peroxidation of the sperm membranes was determined by measuring malondialdehyde (MDA) and 4-hydroxialkenals (HAE) formation.

Results: TNF-, IL-8 and IFN- increased the level of sperm membrane lipid peroxidation when tested at physiological concentrations. At infection-inflammation concentrations, only IL-8 was able to produce a higher effect. When assayed in the presence of leucocytes, IL-8 and TNF- showed a higher effect at infection-inflammation concentrations than at physiological concentrations. Finally, IL-8 showed a higher effect in the presence of leukocytes than in their absence at both physiological and infection-inflammation concentrations. TNF- also showed a higher effect when assayed in the presence of leukocytes than in their absence, but only at infection-inflammation concentrations. There was no effect of IL-6 or IL-10 in any of the tested conditions.

Conclusion: Several pro-inflammatory cytokines at physiological concentrations increase the level of lipid peroxidation of sperm membranes, which could be important for the sperm fecundation process. However, infection-inflammation concentrations of some cytokines, such as IL-8 and TNF-, either alone or in the presence of leukocytes, could drive the lipid peroxidation of the spermatozoa plasma membrane to levels that can affect the sperm fertility capacity.

Keywords: interleukin-6, interleukin-8, interleukin-10, tumor necrosis factor-alpha, interferon-gamma, lipid peroxidation, spermatozoa, infection-inflammation

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