title: Human colonic myogenic dysfunction induced by mucosal lipopolysaccharide translocation and oxidative stress.
abstract: BACKGROUND
  Impairment of gastrointestinal motility is frequently observed in patients with severe infection.
  
  
  OBJECTIVE
  To assess whether exposure of human colonic mucosa to pathogenic lipopolysaccharide affects smooth muscle contractility.
  
  
  METHODS
  Human colonic mucosa and submucosa were sealed between two chambers, with the luminal side facing upwards and covered with Krebs solution, with or without lipopolysaccharide from a pathogenic strain of Escherichia coli (O111:B4; 1,000 ng/mL), and with the submucosal side facing downwards into Krebs. The solution on the submucosal side was collected following 30-min mucosal exposure to Krebs without (N-undernatant) or with lipopolysaccharide (lipopolysaccharide undernatant). Undernatants were tested for lipopolysaccharide and hydrogen peroxide levels and for their effects on smooth muscle cells in the presence of catalase, indomethacin or MG132.
  
  
  RESULTS
  Smooth muscle cells incubated with N-undernatant had a maximal contraction of 32 ± 5% that was reduced by 62.9 ± 12% when exposed to lipopolysaccharide undernatant. Inhibition of contraction was reversed by catalase, indomethacin and MG132. Lipopolysaccharide levels were higher in the lipopolysaccharide undernatant (2.7 ± 0.7 ng/mL) than in N-undernatant (0.45 ± 0.06 ng/mL) as well as hydrogen peroxide levels (133.75 ± 15.9 vs 82 ± 7.5 nM respectively).
  
  
  CONCLUSIONS
  Acute exposure of colonic mucosa to pathogenic lipopolysaccharide impairs muscle cell contractility owing to both lipopolysaccharide mucosal translocation and production of free radicals.
authors.affiliation: Department of Digestive Disease, Campus Bio Medico University, Rome, Italy. Electronic address: m.guarino@unicampus.it.
authors.forename: Michele Pier Luca
authors.initials: MP
authors.lastname: Guarino
authors.forename: Rosa
authors.initials: R
authors.lastname: Sessa
authors.forename: Annamaria
authors.initials: A
authors.lastname: Altomare
authors.forename: Silvia
authors.initials: S
authors.lastname: Cocca
authors.forename: Marisa
authors.initials: M
authors.lastname: Di Pietro
authors.forename: Simone
authors.initials: S
authors.lastname: Carotti
authors.forename: Giovanna
authors.initials: G
authors.lastname: Schiavoni
authors.forename: Rossana
authors.initials: R
authors.lastname: Alloni
authors.forename: Sara
authors.initials: S
authors.lastname: Emerenziani
authors.forename: Sergio
authors.initials: S
authors.lastname: Morini
authors.forename: Carola
authors.initials: C
authors.lastname: Severi
authors.forename: Michele
authors.initials: M
authors.lastname: Cicala
mesh_terms: D000368:Aged; D002374:Catalase / Q000494:pharmacology; D003106:Colon / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis; D007213:Indomethacin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000033:anatomy & histology / Q000187:drug effects* / Q000503:physiopathology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D018384:Oxidative Stress
chemical_list: D008070:Lipopolysaccharides; C440499:lipopolysaccharide, Escherichia coli O111 B4; D006861:Hydrogen Peroxide; D002374:Catalase; D007213:Indomethacin
keywords: Human colonic muscle cells; Lipopolysaccharide; Lipopolysaccharide-induced motility impairment; Oxidative stress