title: Heat shock stress ameliorates cytokine mixture-induced permeability by downregulating the nitric oxide and signal transducer and activator of transcription pathways in Caco-2 cells.
abstract: Proinflammatory cytokines are known to impair intestinal barrier function and to activate signaling pathways, whereas heat shock responses prevent cytokine-induced mucosal damage. We hypothesized that heat shock response blocks the effects of proinflammatory cytokines by regulating nitric oxide (NO) production and the activities of the Janus kinase/signal transducer and activator of transcription (STAT) pathway. A monolayer of Caco-2 cells were pretreated with sodium arsenite (SA, 500 micromol/L) for 1 h, followed by a 1-h recovery, and then stimulated with a cytokine mixture (cytomix: tumor necrosis factor alpha [10 ng/mL], interferon beta [1000 U/mL], and interleukin [IL] 1beta [1 ng/mL]) for 24 h. The permeability of horseradish peroxidase and fluorescein isothiocyanate-conjugated Dextran and transepithelial resistance and potential difference were measured in Ussing chambers. Interleukin-6, IL-8, NO, inducible NO synthase mRNA, STAT activity, and suppressor of cytokine signaling (SOCS) expression were measured in medium or cell lysates. Cytomix resulted in increased epithelial permeability of both fluorescein isothiocyanate-conjugated Dextran and horseradish peroxidase; whereas treatment of Caco-2 cells with SA 500 micromol/L blocked the cytomix-induced permeability changes. In addition, SA treatment decreased cytomix-induced NO production and inducible NO synthase mRNA expression and decreased the levels of STAT1, STAT3, SOCS1, and SOCS3. The SA treatment also decreased cytomix-induced IL-6 and IL-8 production in a dose-dependent manner. In conclusion, cytomix increased epithelial permeability, which is associated with increased NO and STAT activities. The SA treatment ameliorated cytomix-induced permeability, possibly through the downregulation of the NO and Janus kinase/STAT pathways.
authors.affiliation: Department of Research, Shriners Hospital for Children, and Department of Surgery, University of Cincinnati, Cincinnati OH 45229-3229, USA.
authors.forename: Quan
authors.initials: Q
authors.lastname: Wang
authors.forename: Xia-Ling
authors.initials: XL
authors.lastname: Guo
authors.forename: Greg
authors.initials: G
authors.lastname: Noel
authors.forename: Cora
authors.initials: C
authors.lastname: Ogle
mesh_terms: D018938:Caco-2 Cells; D016207:Cytokines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D018869:Heat-Shock Response / Q000187:drug effects*; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects*; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D016207:Cytokines; D009569:Nitric Oxide