Reproduction Abstracts

Introduction: It is understood that active agents in seminal fluid are key to initiating and coordinating mating-induced immunomodulation. This study aimed to characterise the structure of a network of cytokines whose interactions are thought to underpin this process in rats and mice.

Methods: Seminal fluid, collected from isolated seminal glands, and serum, collected by cardiac puncture, were obtained from sexually mature Wistar rats (n=20) and CD1 mice (n=18). Samples were profiled for interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12 (p40), IL-12 (p70), IL-13, IL-17, eotaxin, granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon (IFN)-gamma, IFN-gamma inducible protein (IP)-10, keratinocyte-derived chemokine (KC), leptin, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, regulated on activation, normal T cell expressed and secreted (RANTES), tumour necrosis factor (TNF)-alpha and vascular endothelial growth factor (VEGF) by 24-plex fluid-phase cytometric immunoassay. Bayesian modelling methods were applied to these data to illustrate their relative interrelationships.

Results and discussion: In rats, IL-2, IL-9, IL-12 (p70), IL-13, IL-18, eotaxin, IFN-gamma, IP-10, KC, leptin, MCP-1, MIP-1 alpha and TNF-alpha were significantly higher in serum, whilst IL-1 beta, IL-5, IL-6, IL-10, IL-17, G-CSF and GM-CSF were significantly higher in seminal fluid. In mice, IL-1 alpha, IL-1 beta, IL-2, IL-5, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-17, GM-CSF, IFN-gamma, MCP-1 and TNF-alpha levels were significantly higher in serum IL-4, G-CSF, eotaxin, KC and RANTES exhibited the opposite trend. The characterisation of physiological cytokine profiles in seminal fluid using Bayesian models has allowed a more detailed inference of likely inter-mediator causal relationships and their interspecific conservation. These models suggested that MCP-1 plays a key role in coordinating seminal cytokine networks in vivo in both species, in part through its effects on KC and RANTES. (Funding: Ostara Biomedical).