title: Proteinase-activated receptor-2 in the pathogenesis of gastroesophageal reflux disease.
abstract: OBJECTIVE
  The proteinase-activated receptor-2 (PAR-2) is activated by serine proteases and has been demonstrated to induce proinflammatory and neuroinflammatory effects. It is considered to alter transepithelial resistance and mediates visceral hypersensitivity. This study aimed to evaluate the expression of PAR-2 in human esophageal mucosa of patients with gastroesophageal reflux disease (GERD) in relation to mucosal alterations.
  
  
  METHODS
  The study included 123 patients with GERD stratified to erosive reflux disease (n=50), non-erosive reflux disease (n=46), and reflux-negative patients as controls (n=27). Endoscopic and histopathological characterization was performed according to the Los Angeles classification and modified Ismail-Beigi criteria, respectively. PAR-2 expression was analyzed by quantitative reverse transcription (RT)-PCR and immunohistochemistry. The gene expression levels of interleukin (IL)-8 were determined by quantitative RT-PCR and correlated to PAR-2 expression in each patient. Performing in vitro studies, esophageal squamous cell lines (KYSE 150, KYSE 450) were incubated, adjusted to different pH (7.0, 6.0, and 5.0), and exposed to bile acids and PAR-2-activation peptide (SLIGKV-NH(2)).
  
  
  RESULTS
  PAR-2 gene expression was 7- to 10-fold upregulated (P<0.0001) in the mucosa of patients with GERD and correlated positively with IL-8 expression and with histomorphological alterations (dilated intercellular spaces, papillary elongation, basal cell hyperplasia (BCH); P<0.01). Immunohistochemistry showed an intense staining of PAR-2 throughout all epithelial layers in patients with GERD compared with controls (P=0.0005). In vitro studies revealed a 1.5- to 20-fold induction of PAR-2 gene expression in esophageal squamous cells by acidified medium (P<0.01), but not by additional bile acids. The activation of PAR-2 leads to expression and secretion of IL-8.
  
  
  CONCLUSIONS
  This study provides evidence of the functional importance of PAR-2-mediated pathways in the pathogenesis of GERD and GERD-associated mucosal alterations and inflammatory changes.
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Kandulski
authors.forename: Thomas
authors.initials: T
authors.lastname: Wex
authors.forename: Klaus
authors.initials: K
authors.lastname: Mönkemüller
authors.forename: Doerthe
authors.initials: D
authors.lastname: Kuester
authors.forename: Lucia C
authors.initials: LC
authors.lastname: Fry
authors.forename: Albert
authors.initials: A
authors.lastname: Roessner
authors.forename: Peter
authors.initials: P
authors.lastname: Malfertheiner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002460:Cell Line; D016099:Endoscopy, Gastrointestinal; D004947:Esophagus / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism* / Q000473:pathology; D005764:Gastroesophageal Reflux / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D015854:Up-Regulation
chemical_list: D016209:Interleukin-8; D012333:RNA, Messenger; D044464:Receptor, PAR-2