Transforming growth factor-beta (TGF beta) in porcine seminal plasma

Abstract

Bioactive factors in seminal plasma induce cellular and molecular changes in the female reproductive tract after coitus. An active constituent of seminal plasma in mice and humans is the potent immune-modulating cytokine transforming growth factor-b (TGFb). To investigate whether TGFb is present in boar seminal plasma, TGFb1 and TGFb2 were measured by immunoassay. High levels of TGFb1 and TGFb2 were detected in 100% of seminal fluid samples from 73 boars. Both were predominantly in the active, not latent form. Interferon-g (IFNg) and lipopolysaccharide (LPS), agents that interact with TGFb signalling, were detectable in 5% and 100% of samples, respectively. TGFb1 and TGFb2 concentrations varied widely between boars, but correlated with each other and with sperm density, and remained relatively constant within individual boars over a 6-month period. Frequent semen collection substantially diminished the concentration of both TGFb isoforms. Using retrospective breeding data for 44 boars, no correlation between TGFb content and boar reproductive performance by artificial insemination (AI) with diluted semen was found. It is concluded that TGFb is abundant in boar seminal plasma, leading to the speculation that, in pigs, TGFb may be a male–female signalling agent involved in immune changes in the female reproductive tract elicited by seminal fluid.