title: Interleukins 4 and 13 increase intestinal epithelial permeability by a phosphatidylinositol 3-kinase pathway. Lack of evidence for STAT 6 involvement.
abstract: Interleukins 4 and 13 can affect their target cells by activation of signal transducer and activator of transcription 6 (STAT 6) or phosphatidylinositol 3-kinase (PI3K). We examined the signal transduction events involved in IL-4 and IL-13 regulation of epithelial paracellular permeability using T84 cells, a model human colonic epithelium. T84 cells treated with IL-4 or IL-13 displayed virtually identical dose- and time-dependent STAT 6 activation as assessed by electrophoretic mobility shift assay (EMSA) and decreases in transepithelial resistance (TER). STAT 6 DNA binding activity was maximal in nuclear extracts 30 min after exposure to IL-4 or IL-13, and TER was maximally reduced by 24 h post-treatment. Pretreatment of epithelia with transcription factor decoys (phosphorothioated DNA oligonucleotides containing the STAT 6 binding site) dramatically reduced STAT 6 activation as detected by EMSA, but did not attenuate the TER reduction by IL-4 or IL-13. In contrast, although the PI3K inhibitors wortmannin and LY294002 did not affect IL-4 or IL-13 STAT 6 activation, they significantly inhibited the ability of either cytokine to lower TER. Thus, we provide evidence for PI3K as the major proximal signaling event in IL-4 and IL-13 regulation of TER and speculate that pharmacological targeting of enterocytic PI3K activity may represent a means to manipulate epithelial permeability.
authors.affiliation: Intestinal Disease Research Programme and Infection and Immunity Programme, McMaster University, Hamilton, Ontario L8N 3Z5, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ceponis
authors.forename: F
authors.initials: F
authors.lastname: Botelho
authors.forename: C D
authors.initials: CD
authors.lastname: Richards
authors.forename: D M
authors.initials: DM
authors.lastname: McKay
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D050800:STAT6 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects*; D015534:Trans-Activators / Q000502:physiology*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D018793:Interleukin-13; D009025:Morpholines; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D015847:Interleukin-4; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004247:DNA; D019869:Phosphatidylinositol 3-Kinases; D000077191:Wortmannin