EXPERIMENTAL STUDY Tumor necrosis factor-alpha (TNF-a) promotes cell survival during spermatogenesis, and this effect can be blocked by infliximab, a TNF-a antagonist

Objective: Tumor necrosis factor-alpha (TNF-a) has been shown to inhibit germ cell death in human seminiferous epithelium. In the present study, we wanted to explore the effects of TNF-a in the rat seminiferous epithelium and to study molecular mechanisms of germ cell apoptosis. Furthermore, the effects of infliximab were studied. Infliximab is a TNF-a antagonist used in autoimmune disorders, such as rheumatoid arthritis and Crohn’s disease. Methods: Rat seminiferous tubule segments were cultured in the presence and absence of TNF-a, infliximab and SN50, a NF-kB inhibitor. TUNEL-staining and cleaved caspase-3 immunohistochemistry combined with squash preparations of rat seminiferous tubule segments were used to evaluate the number of apoptotic cells. Western blot analyses were performed on cultured seminiferous tubule segments for Bcl-2 family proteins (Bax, Bad, Bcl-w, Bcl-xL) and fas ligand. Results: TNF-a promotes cell survival in the rat seminiferous epithelium, and this prosurvival effect can be blocked by infliximab, a TNF-a antagonist. Bcl-xL was found to be upregulated in mitochondrial membranes by TNF-a, and this upregulation was inhibited by infliximab. Inhibition of NF-kB translocation to the nucleus prevented the prosurvival effect of TNF-a on seminiferous epithelium. Conclusions: The present study demonstrates that TNF-a promotes cell survival in the rat seminiferous epithelium, and this effect can be blocked by infliximab. This is the first study to show the effects of infliximab in the testis. The prosurvival effect of TNF-a might be at least partly mediated by modulating the expression and subcellular localization of Bcl-2 family proteins. European Journal of Endocrinology 151 629–640