Title: Role of Insulin in the Activation of NF-κB/IκB Pathway in Macrophage Cells
Abstract: Background: Sepsis still has a high mortality rate despite adequate supportive care.Newer therapeutic modalities have been developed but they have generally ended in failure.Recently, insulin was reported to have an antiinflammatory effect by inhibiting the IκB/NF-κB pathway, and may have therapeutic potential in sepsis.However, the precise mechanism of the anti-inflammatory effect of insulin is unclear.This study examined the role of insulin in activating IκB/NF-κB in macrophage.Methods: Raw 264.7 cells, a murine macrophage cell line, were used in this experiment.Western blotting using IκB Ab and phosphor-specific IκB Ab was performed to evaluate the degradation and phosphorylation of IκB cells.For the IκB Kinase (IKK) activity, an immune complex kinase assay was performed.The level of interleukin-6 (IL-6) was measured by ELISA to determine the level of proinflammatory cytokine.Results: IκBα degradation began 30 min after lipopolysaccharide (LPS) treatment.However, an insulin pretreatment suppressed the IκBα degradation caused by the LPS treatment.The phosphorylation of IκBα and IKK activity was also inhibited by the insulin pretreatment.Finally, the insulin pretreatment showed a tendency to suppress the induction of IL-6 by LPS.Conclusion: Insulin might have an anti-inflammatory effect though partial inhibition of the IκB/NFκB pathway in macrophage cell lines.