Differences in the Mode of Phagocytosis of Bacteria between Macrophages and Testicular Sertoli Cells

Abstract

Sertoli cells, the sole somatic cell type in the seminiferous epithelium, play an essential role in spermatogenesis and spermiogenesis by nursing germ cells for their survival and differentiation as well as physically inhibiting the entrance of harmful substances into the seminiferous tubules. Sertoli cells possess the characteristics of immune cells; they express pattern recognition receptors, secrete antimicrobial proteins, and engulf dead or dying cells. In this study, we determined the mechanism by which Sertoli cells engulf and kill bacteria compared to that of macrophages. When the primary cultured Sertoli cells of rats were incubated with Staphylococcus aureus, they produced the mRNA of neutrophil protein 3, an antimicrobial peptide of the α-defensin family, but not superoxide or nitric oxide, in contrast to mouse peritoneal macrophages. Sertoli cells effectively phagocytosed S. aureus in a manner that was accompanied by cytoskeleton rearrangement and dependent on phosphatidylinositol 3-kinase. Engulfed bacteria appeared to stay alive in Sertoli cells, while they were rapidly killed in macrophages. These results collectively suggest that Sertoli cells eliminate bacteria that have invaded the seminiferous epithelium without evoking inflammation, unlike macrophages. © 2013, International Research and Cooperation Association for Bio & Socio-Sciences Advancement. All rights reserved.