LPS Increases the Expression Levels of IL-18, ICE and IL-18 R in Mouse Testes Mahmoud Abu Elhija 1,3 , Eitan Lunenfeld 2,3 , Mahmoud Huleihel 1,3 1 The Shraga Segal Department of Microbiology and Immunology, Beer-Sheva, Israel; 2 Department of Obstetrics and Gynecology, Soroka University Medical Center, Beer-Sheva, Israel; 3 Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel Introduction Spermatogenesis is a process of proliferation and dif- ferentiation of germ cells, which is controlled by endocrine and autocrine ⁄ paracrine factors. 1,2 In addition to the regulatory effect of gonadotropins and androgens on the initiation and maintenance of spermatogenesis, a number of cytokines are also involved in the regulation of various differentiation steps in this process. 3–5 Keywords Germ cells, interleukin-18, LPS, spermatogenesis, testis Correspondence Mahmoud Huleihel, The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion-University of the Negev, Beer-Sheva, Israel. E-mail: huleihel@bgu.ac.il Submitted March 17, 2008; accepted May 31, 2008. Citation Abu Elhija M, Lunenfeld E, Huleihel M. LPS increases the expression levels of IL-18, ICE and IL-18 R in mouse testes. Am J Reprod Immunol 2008; 60: 361–371 doi:10.1111/j.1600-0897.2008.00636.x Problem This study examined the effect of intraperitoneal administration of lipo- polysaccharide (LPS) to adult male mouse on the expression levels of interleukin-18 (IL-18), IL-18 receptor (IL-18R) and the IL-1b converting enzyme (ICE) (IL-18 family) in their testes and spleen (control). Method of study Adult mice were injected (intraperitoneally; i.p.) with saline (control) or LPS (2, 20, 100 lg ⁄ mL; 100 lL ⁄ mouse). After 3 and 24 hr, testes and spleen were collected. Testicular tissue was examined for IL-18 (by ELISA, real time PCR, and western blot analysis), IL-18R and ICE (wes- tern blot and real time PCR analysis) and spleen tissue was examined for the IL-18 family by real time PCR analysis. Student’s t-test was used for statistical analysis. Results Homogenates of mouse testes contain and express basal levels of IL-18, ICE and IL-18 R. The expression levels of IL-18, ICE and IL-18R were significantly increased 3 and 24 hr after intraperitoneal injection of LPS to mature mouse, as examined by ELISA, western blot and real time PCR analysis. However, the expression levels of IL-18, ICE and IL-18Ra in the spleen increased significantly only after 24 hr of LPS stimulation, as examined by real time PCR. Conclusion Our results demonstrate that LPS increases the expression levels of the IL-18 family in mouse testis and spleen, but the time of expression dif- fers between the two organs. The presence of IL-18 in the testes might be involved in the regulation of physiological and infection ⁄ inflamma- tory processes, and may be part of the autocrine ⁄ paracrine factors that control spermatogenesis. Further studies should be performed to confirm this possibility. ORIGINAL ARTICLE American Journal of Reproductive Immunology 60 (2008) 361–371 ª 2008 The Authors Journal compilation ª 2008 Blackwell Munksgaard 361