Cytokine-induced functional suppression of microencapsulated rat pancreatic islets in vitro

Background, It is likely that inflammatory cytokines are released near micr oencapsulated islets in vivo. Methods. Rates of insulin release or glucose oxidation were measured after culture of microencapsulated rat islets with interleukin (IL)-1 beta and tu mor necrosis factor-(TNF-alpha). Their ability to recover from IL-1 beta-in duced suppression was also investigated. Results, Microencapsulated islets were suppressed after exposure to IL-1 be ta, which was potentiated by TNF-alpha. After exposure to lower IL-1 beta c oncentrations, microencapsulated islets had similar oxidation rates as corr esponding controls. At higher concentrations, microencapsulated islets were more suppressed than nonencapsulated islets, Microencapsulated and control islets were able to recover from suppression after exposure to 2.5 U/ml of IL-1 beta, Conclusions. Microencapsulation using the present alginate/poly-L-lysine/al ginate capsules does not protect islets against the detrimental effects of IL-1 beta and TNF-alpha. Indeed, microencapsulated islets seem to be more s usceptible to suppression at higher concentrations of IL-1 beta, However, a fter exposure to a lower concentration of IL-1 beta, microencapsulated isle ts can recover.