Differential Interleukin-6 Protein and mRNA Expression levels in Angiotensin II Treated Cultured Rat Astrocytes

Objective: To study the effects of Angiotensin (Ang) II on Interleukin-6 (IL-6) expression from cultured rat astrocytes at the transcriptional and translational levels. Background: Ang II is a multifunctional octapeptide of the Renin Angiotensin System (RAS) that acts as a key, proinflammatory molecule and growth factor. Evidence from previous studies showed that Ang II modulates IL-6 protein and mRNA levels in different cell types. In this study, we investigated the time-dependent effects of Ang II on IL-6 protein and mRNA levels in astrocytes isolated from different brain regions of Wistar rats. Methods: Astrocytes were isolated and cultured from the cerebellum (CB) and the brainstem (BS) regions of neonatal Wistar rat brains. Quiescent astrocytes were treated with 100nM Ang II at various time points, and mRNA and protein were isolated from these cells. IL-6 protein and mRNA levels were measured using western blot and real time polymerase chain reaction techniques, respectively. Results: Ang II induced IL-6 protein and mRNA expression from both CB and BS astrocytes at all-time points examined. However, compared to the protein levels, increases in IL-6 mRNA expression levels were more robust in both CB and BS astrocytes. As IL-6 protein is secreted from astrocytes, studies are ongoing to measure the secretion of IL-6 in the culture media using an ELISA assay. Conclusion: Findings from this study showed that, Ang II induces IL-6 protein and mRNA levels from astrocytes isolated from both CB and BS brain regions in a time-dependent manner suggesting that Ang II has proinflammatory actions in astrocytes.