title: The intestinal barrier in irritable bowel syndrome: subtype-specific effects of the systemic compartment in an in vitro model.
abstract: BACKGROUND
  Irritable bowel syndrome (IBS) is a disorder with multifactorial pathophysiology. Intestinal barrier may be altered, especially in diarrhea-predominant IBS (IBS-D). Several mediators may contribute to increased intestinal permeability in IBS.
  
  
  OBJECTIVE
  We aimed to assess effects of tryptase and LPS on in vitro permeability using a 3-dimensional cell model after basolateral cell exposure. Furthermore, we assessed the extent to which these mediators in IBS plasma play a role in intestinal barrier function.
  
  
  METHODS
  Caco-2 cells were grown in extracellular matrix to develop into polarized spheroids and were exposed to tryptase (10 - 50 mU), LPS (1 - 50 ng/mL) and two-fold diluted plasma samples of 7 patients with IBS-D, 7 with constipation-predominant IBS (IBS-C) and 7 healthy controls (HC). Barrier function was assessed by the flux of FITC-dextran (FD4) using live cell imaging. Furthermore, plasma tryptase and LPS were determined.
  
  
  RESULTS
  Tryptase (20 and 50 mU) and LPS (6.25 - 50 ng/mL) significantly increased Caco-2 permeability versus control (all P< 0.05). Plasma of IBS-D only showed significantly elevated median tryptase concentrations (7.1 [3.9 - 11.0] vs. 4.2 [2.2 - 7.0] vs. 4.2 [2.5 - 5.9] μg/mL; P<0.05) and LPS concentrations (3.65 [3.00 - 6.10] vs. 3.10 [2.60-3.80] vs. 2.65 [2.40 - 3.40] EU/ml; P< 0.05) vs. IBS-C and HC. Also, plasma of IBS-D increased Caco-2 permeability versus HC (0.14450 ± 0.00472 vs. 0.00021 ± 0.00003; P < 0.001), which was attenuated by selective inhibition of tryptase and LPS (P< 0.05).
  
  
  CONCLUSIONS
  Basolateral exposure of spheroids to plasma of IBS-D patients resulted in a significantly increased FD4 permeation, which was partially abolished by selective inhibition of tryptase and LPS. These findings point to a role of systemic tryptase and LPS in the epithelial barrier alterations observed in patients with IBS-D.
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Samefko
authors.initials: S
authors.lastname: Ludidi
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Daisy
authors.initials: D
authors.lastname: Jonkers
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Elhaseen
authors.initials: E
authors.lastname: Elamin
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Harm-Jan
authors.initials: HJ
authors.lastname: Pieters
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: Schaepkens
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Bours
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kruimel
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: José
authors.initials: J
authors.lastname: Conchillo
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism-Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: Ad
authors.initials: A
authors.lastname: Masclee
mesh_terms: D018938:Caco-2 Cells; D005109:Extracellular Matrix; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects*; D043183:Irritable Bowel Syndrome / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D053802:Tryptases / Q000494:pharmacology*
chemical_list: D008070:Lipopolysaccharides; D053802:Tryptases