Seminal Plasma Cytokines Are Predictive of the Outcome of Boar Sperm Preservation

Abstract

Boar seminal plasma is rich in cytokines, which could influence the capability of spermatozoa to tolerate preservation.

Objectives: To evaluate the involvement of boar seminal plasma cytokines in the changes experienced by boar spermatozoa during their storage, either in liquid or frozen state.

Materials and Methods: In two separated experiments, semen samples from healthy and fertile boars were split in two aliquots, one centrifuged twice (1,500 ×g for 10 min) to harvest seminal plasma, whereas the other was either commercially extended (3 × 107 sperm/mL) and liquid-stored at 17°C during 144 h (n = 28, Experiment 1) or frozen-thawed using a standard 0.5 mL protocol (n = 27, Experiment 2). Sixteen cytokines were quantified using Luminex xMAP®. Sperm attributes (CASA-evaluated total and progressive motility; flow cytometry-evaluated sperm viability, production of intracellular H2O2 and O∙−2 and levels of lipid peroxidation in viable spermatozoa) were evaluated either at 0, 72, or 144 h of liquid storage (Experiment 1) or before freezing and at 30- and 150-min post-thawing (Experiment 2).

Results: Multiple linear regression models, with Bayesian approach for variable selection, revealed that the anti-inflammatory TGF-β2, TGF-β3, IL-1Ra, and IL-4 and the pro-inflammatory IL-8 and IL-18, predicted changes in sperm motility for liquid-stored semen while the anti-inflammatory IFN-γ was included in the models predicting changes in all sperm attributes for cryopreserved semen.

Conclusion: Specific boar seminal plasma cytokines would contribute to modulate the structural and metabolic changes shown by spermatozoa during preservation, either in liquid or frozen state