Mechanisms of Interferon- -Induced Survival in Fetal and Neonatal Primary Astrocytes

Abstract

Background: We have previously shown that interferon-β (IFN-β) is a potent promoter of astrocyte survival. Although the mechanism(s) by which IFN-β promotes astrocyte survival have not been completely elucidated, it has been shown that IFN-β directly stimulates survival signaling pathways. In the present report, we took advantage of the differences in the susceptibility of fetal and neonatal astrocytes to apoptosis to further investigate the mechanism(s) underlying the antiapoptotic effect of IFN-β. Methods: Primary monolayer cultures of cortical astrocytes were established from neonatal (3- to 6-day-old) or fetal (embryonic days: E15 or E17) Sprague-Dawley rat cerebral cortices. Apoptotic cell death was determined by fluorescent-microscopic analysis of staining patterns of cell DNA with Hoechst 33258, and determination of annexin V binding.Akt phosphorylation was detected by Western blottingusing a commercial kit that allows specific recognition of both non-phosphorylated and serine-phosphorylated Akt. Results: In the present work, we have found that primary astrocytes obtained from neonatal rats are resistant to apoptosis induced by serum starvation, though cell death may be induced by combining serum starvation with sodium butyrate treatment. This effect is counteracted by IFN-β treatment through a mechanism that involves phosphatidylinositol 3-kinase stimulation. Conclusions: IFN-β can be considered as a neuroprotective agent and, therefore, part of its beneficial effects in multiple sclerosis (MS) treatment may depend on its capacity to protect astrocytes against the apoptotic cell death that occurs in the course of the MS lesions.