PI3K and potentially autophagy are involved in HSV, Flu, SeV, and CpG A -stimulated IFN-α production by human plasmacytoid dendritic cells (135.51)

Abstract

Abstract IFN-α production plays a critical role in the immune system and as "professional" type I interferon (IFN) producing cells, plasmacytoid dendritic cells (pDC) can produce much more IFN-α in response to viruses than other cell types in response to TLR-7 and -9 stimulation. Phosphatidylinositol-3 kinase (PI3K) has been shown to be activated by TLR stimulation in many cell types and is essential in the regulation of many processes, including autophagy. A role for PI3K and autophagy in pDC has been recently described. The role of autophagy in induction of IFN-α in human pDC, however, has not been described. We investigated the effects of wortmannin, a PI3K inhibitor, and 3-methyladenine (3MA), a specific inhibitor of autophagy, but also an inhibitor of PI3K, on IFN-α?production by HSV, Flu, SeV, and CpG A -stimulated human pDC. pDC were pretreated with the inhibitors then stimulated with virus for 6hr for detection of intracellular IFN-α by intracellular flow cytometry or overnight for stimulation and release of IFN-α, which was detected by ELISA. Inhibition of PI3K with wortmannin, inhibited IFN-α production by pDC. Moreover, 3MA also inhibited IFN-α production by HSV, Flu, SeV, and CpG A-stimulated pDC. In addition, 3MA inhibited HSV-induced LC3B aggregation in pDC, a marker for autophagy. These results support key roles for the PI3K pathway and perhaps, autophagy, in mediating IFN-α secretion and virus detection by human pDC. Supported by AI26806.