ABSTRACT
Objective To investigate if there is any effect of interleukin-18 (IL-18) or if IL-18 modulates IL-1? effects on islet function.Methods Insulin release and nitrite production from isolated islets of newborn Wistar rats were measured after incubation with or without cytokines.Reverse transcription polymerase chain reaction (RT-PCR) was used to detect mRNA expression of the IL-18 receptor signaling chain (IL-18R?).Results (1) There were no significant effects of 0.625～10nmol/L of recombinant murine (rm) IL-18 alone on accumulated or glucose-challenged insulin release and nitrite production after 24h.(2) 15pg/ml of recombinant human (rh) IL-1? significantly increased nitrite production and inhibited insulin release.However,0.625～10nmol/L of rm IL-18 failed to modulate the above effects caused by IL-1?.(3) 24h rm IL-12 preincubation failed to sensitize islets to the effects of 10nmol/L of rm or recombinant rat (rr) IL-18 alone or to prime islets to IL-1? actions on insulin release and nitrite production.(4) IL-18R? mRNA was not expressed in isolated islets even after exposure to IL-12 for 48h.Conclusion Unlike IL-1?,IL-18 dose not play a direct role in the destruction of islet ?-cell function.