Macrophage metalloelastase-12 is detectable in human seminal plasma and represents a predictor for inflammatory processes in the male genital tract

Macrophage metalloelastase-12 (MMP-12), a protein of the matrix metalloproteinase family, is involved in the breakdown of extracellular matrix in normal physiological processes as well as in disease processes. MMP-12 is almost exclusively produced by macrophages and is associated with inflammatory disorders. Giving the fact that inflammation negatively influences ejaculate parameters, we investigated a possible presence and correlation of MMP-12 in seminal plasma with parameters of the ejaculate, especially in leucocytospermic ejaculates. Forty-two patients who presented for semen analysis were assigned into four groups depending on the result of semen analysis according to the WHO guidelines 2010: normozoospermia (n=11), OAT (n=10), azoospermia (n=10) and leucocytospermia (>1 mio. peroxidase-positive cells per ml) (n=11). MMP-12 was detected by ELISA and was measurable in nearly all seminal plasma samples. Generally, MMP-12 concentrations were significantly higher in leucocytospermic samples than in nonleucocytospermic ones (P=0.001). The MMP-12 levels between the latter nonleucocytospermic groups did not differ. Moreover, MMP-12 levels correlated with the presence of peroxidase-positive leucocytes. No correlation with CD 14 positive monocytes/macrophages was detected. In this study, we demonstrate that MMP-12 is present in seminal plasma and is correlated with inflammatory conditions in human semen and therefore may serve as predictor of ongoing inflammatory processes.