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

Abstract

<b>Background:</b> Boar seminal plasma is rich in cytokines, which could influence the capability of spermatozoa to tolerate preservation. <b>Objectives:</b> 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. <b>Materials and Methods:</b> 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 (<i>n</i> = 28, Experiment 1) or frozen-thawed using a standard 0.5 mL protocol (<i>n</i> = 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mtext>O</mml:mtext></mml:mrow> <mml:mrow><mml:mn>2</mml:mn></mml:mrow> <mml:mrow><mml:mo>•</mml:mo> <mml:mo>-</mml:mo></mml:mrow> </mml:msubsup> </mml:math> 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). <b>Results:</b> 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. <b>Conclusion:</b> 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.