Lipopolysaccharide increased the expression levels of IL-18, ICE and IL-18 R in murine Leydig cells

PROBLEM: This study examined the effect of lipopolysaccharide (LPS) on the capacity of Leydig cells to produce and express interleukin-18 (IL-18), IL-18 receptor (IL-18R) and the IL-1beta-converting enzyme (ICE) (IL-18 family), under in vitro conditions. METHOD OF STUDY: Primary Leydig cells (LCs) were isolated from murine testis by the Percoll technique, and cultured both in the presence and absence of LPS (0.1, 1, 5 microg/mL) for 3 and 24 hr. LCs were examined for their capacity to produce and express IL-18 family molecules by using immunohistochemical staining (IHC), enzyme-linked immunosorbent assay (ELISA), Western blot and real-time polymerase chain reaction (PCR) analysis. RESULTS: Leydig cells were shown to constitutively express IL-18, as examined by IHC, ELISA, Western blot and real-time PCR analysis. Addition of LPS to LC cultures was shown to significantly increase the basal levels of IL-18, in a dose- and time course-dependent manner, as examined by ELISA, Western blot and real-time PCR analysis. In addition, LPS increased LC cultures to express ICE and IL-18 R, as examined by real-time PCR analysis. CONCLUSION: Our results demonstrate that LPS increased the capacity of murine LCs to produce the IL-18 family molecules. IL-18, in the testis, might be involved in the regulation of physiological and infection/inflammatory processes, and thus, could be a component of the autocrine/paracrine factor net that controls steroidogenesis and male fertility; further studies are needed to confirm this possibility.