Angiotensin II causes imbalance between pro- and anti-inflammatory cytokines by modulating GSK-3β in neuronal culture.

BACKGROUND AND
PURPOSE: Emerging evidence indicates that the balance between pro-inflammatory cytokines (PICs) and anti-inflammatory cytokines (AICs) within the brain is an important determinant in the outcome of hypertension. However, the mechanism by which this dysregulation occurs is not known. We aimed to investigate whether AngII induces imbalance between PIC and AIC by modulating downstream transcription factors, NFκB and cyclic AMP response element-binding protein (CREB), and whether AngII-induced effects are mediated by glycogen synthase kinase-3β (GSK-3β). EXPERIMENTAL APPROACH: CATH.a neurons were exposed to AngII (10 nM-1 μM) over a preset time course. In another set of experiments, GSK-3β was knock down by using lentivirus containing short hairpin RNA targeting GSK-3β (L-sh-GSK3β) before AngII exposure. Cell extracts were subjected to RT-PCR, immunoblot and immunoprecipitation. KEY
RESULTS: AngII caused time-dependent increase in PICs (TNF-α and IL-1β) and reduction in AIC (IL-10). AngII exposure caused reduced phosphorylated CREB(Ser-133) and increased p-NFκB(Ser-276) levels, leading to reduced CREB-CBP and increased NFκB-CBP binding. These results were accompanied by increased activation of GSK-3β, as indicated by increased p-GSK3(Tyr-216) to p-GSK3(Ser-9) ratio. In a subsequent study, pretreatment with L-sh-GSK3β attenuated AngII-induced alterations in PICs and IL-10 by augmenting CREB-CBP and attenuating NFκB-CBP binding. CONCLUSIONS AND IMPLICATIONS: Collectively, these findings are the first to provide direct evidence that AngII-induced dysregulation in cytokines is mediated by GSK-3β-mediated alterations in downstream transcription factors in neuronal cells. Our data also reveal that AngII-induced effects could be alleviated by GSK-3β inhibition, suggesting GSK-3β as an important therapeutic target for hypertension that is characterized by increased PICs and NFκB activation.