DOI 10.1095/biolreprod.102.011189 Involvement of Tumor Necrosis Factor-a in the Pathogenesis of Autoimmune

We studied the testicular macrophages of rats with experi-mental autoimmune orchitis (EAO) and analyzed whether the tumor necrosis factor-a (TNFa) is involved in germ cell apopto-sis and in Leydig cell steroidogenesis. The EAO was induced in adult male Sprague-Dawley rats by active immunization with testicular homogenate and adjuvants. In the experimental group, a severe orchitis was observed 80 days after the first immuni-zation. ED1- and ED2-positive macrophages were quantified by immunohistochemistry. The TNFa concentration of conditioned media from testicular macrophages (TMCM) was determined by ELISA. The number of apoptotic TNF receptor 1 (TNFR1)-posi-tive germ cells was identified by combining in situ end labeling of apoptotic DNA and immunohistochemical techniques. The ef-fect of TNFa on Leydig cell testosterone production was deter-mined by RIA. In rats with EAO, we observed a significant in-crease in the number of TNFa-positive testicular macrophages, the TNFa concentration in TMCM, and the number of TNFR1-positive germ cells. Sixty percent of TNFR1-positive germ cells were apoptotic. These results suggest that TNFa could be in-volved in the pathogenesis of EAO. Acting together with other local factors such as Fas-FasL, TNFa could trigger germ cell ap-optosis. We also demonstrated that TNFa inhibited in vitro tes-tosterone production in basal and hCG-stimulated Leydig cells from rats with orchitis. apoptosis, cytokines, immunology, testis, testosteron