IVIG activates FcγRIIB-SHIP1-PIP3 Pathway to stabilize mast cells and suppress inflammation after ICH in mice

Sci Rep. 2017 Nov 14;7(1):15583. doi: 10.1038/s41598-017-15455-w.

Abstract

Following intracerebral hemorrhage (ICH), the activation of mast cell contributes to brain inflammation and brain injury. The mast cell activation is negatively regulated by an inhibitory IgG-receptor. It's signals are mediated by SHIP (Src homology 2-containing inositol 5' phosphatase), in particular SHIP1, which activation leads to hydrolyzation of PIP3 (Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3, leading to the inhibition of calcium mobilization and to the attenuation of mast cell activation. Intravenous immunoglobulin (IVIG) is a FDA-approved drug containing IgG. We hypothesized that IVIG will attenuate the ICH-induced mast cell activation via FcγRIIB/SHIP1 pathway, resulting in a decrease of brain inflammation, protection of the blood-brain-barrier, and improvement of neurological functions after ICH. To prove this hypothesis we employed the ICH collagenase mouse model. We demonstrated that while ICH induced mast cell activation/degranulation, IVIG attenuated post-ICH mast cell activation. Mast cell deactivation resulted in reduced inflammation, consequently attenuating brain edema and improving of neurological functions after ICH. Furthermore using siRNA-induced in vivo knockdown approach we demonstrated that beneficial effects of IVIG were mediated, at least partly, via SHIP1/PIP3 pathway. We conclude that IVIG treatment represents a promising therapeutic approach potentially able to decrease mortality and morbidity after ICH in experimental models.

MeSH terms

  • Administration, Intravenous
  • Animals
  • Blood-Brain Barrier / drug effects
  • Brain / drug effects
  • Brain / metabolism
  • Brain / physiopathology
  • Calcium / metabolism
  • Cerebral Hemorrhage / drug therapy*
  • Cerebral Hemorrhage / genetics
  • Cerebral Hemorrhage / immunology
  • Cerebral Hemorrhage / pathology
  • Collagenases / genetics*
  • Collagenases / immunology
  • Disease Models, Animal
  • Humans
  • Immunoglobulin G / administration & dosage
  • Inflammation / drug therapy*
  • Inflammation / genetics
  • Inflammation / immunology
  • Inflammation / pathology
  • Mast Cells / drug effects
  • Mast Cells / metabolism
  • Mice
  • Phosphatidylinositol Phosphates / metabolism
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases / genetics*
  • RNA, Small Interfering / genetics
  • Receptors, IgG / genetics*
  • Receptors, IgG / metabolism
  • Signal Transduction / drug effects

Substances

  • Fcgr2b protein, mouse
  • Immunoglobulin G
  • Phosphatidylinositol Phosphates
  • RNA, Small Interfering
  • Receptors, IgG
  • phosphatidylinositol 3,4,5-triphosphate
  • Inpp5d protein, mouse
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
  • Collagenases
  • Calcium