Inhibition of the phosphatidylinositol-3-kinase pathway abrogates polyinosinic:polycytidylic acid-stimulated hyaluronan-mediated human mucosal smooth muscle cell binding of U937 monocytic cells

J Interferon Cytokine Res. 2010 Nov;30(11):809-16. doi: 10.1089/jir.2009.0061. Epub 2010 Sep 13.

Abstract

The origin of inflammatory bowel disease (IBD) is unknown and likely to be multifactorial. Our laboratory has established that in human mucosal smooth muscle cells (M-SMCs), cellular stress induced by virus or the viral mimic double-stranded RNA (polyinosinic:polycytidylic acid [poly I:C]) increases cell surface hyaluronan (HA) deposition and the formation of long cable-like structures of HA that are important for leukocyte attachment. Since leukocyte accumulation and hyperplasia of the M-SMCs are characteristic pathological changes observed in IBD patients, and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways play established roles in cell survival, we investigated whether this pathway is involved in this unique HA-mediated leukocyte attachment. Poly I:C-stimulated M-SMCs bind significantly more monocytic cells than untreated cells and this response was inhibited in a dose-dependent manner by treatment with the PI3K inhibitor, LY294002. Since Akt is a critical downstream regulator of PI3K, we investigated the phosphorylation status of Akt in M-SMCs after treatment with poly I:C for 1 h and found that Akt was phosphorylated, but the phosphorylated Akt band was undetectable in LY294002 plus poly I:C-treated cultures. Confocal microscopy of M-SMCs stained for HA revealed that HA cable formation after poly I:C treatment was abrogated by LY294002. These results demonstrate that poly I:C-stimulated M-SMCs phosphorylate Akt, produce HA cables, and promote HA-mediated leukocyte adhesion through a PI3K/Akt-dependent manner.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Adhesion* / drug effects
  • Cell Adhesion* / immunology
  • Chromones / pharmacology
  • Humans
  • Hyaluronic Acid / immunology
  • Hyaluronic Acid / metabolism*
  • Immunity, Mucosal
  • Inflammatory Bowel Diseases / drug therapy
  • Inflammatory Bowel Diseases / immunology*
  • Inflammatory Bowel Diseases / metabolism
  • Monocytes / drug effects
  • Monocytes / immunology
  • Monocytes / metabolism*
  • Monocytes / pathology
  • Morpholines / pharmacology
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / immunology
  • Myocytes, Smooth Muscle / metabolism*
  • Myocytes, Smooth Muscle / pathology
  • Phosphoinositide-3 Kinase Inhibitors
  • Poly I-C / immunology
  • Poly I-C / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / immunology
  • U937 Cells

Substances

  • Chromones
  • Morpholines
  • Phosphoinositide-3 Kinase Inhibitors
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Hyaluronic Acid
  • Poly I-C