title: Mucosal expression of aquaporin 5 and epithelial barrier proteins in chronic rhinosinusitis with and without nasal polyps.
abstract: OBJECTIVE
  The purpose of this study is to characterize the association between altered epithelial barrier function, represented by changes in histology and differential expression of the mucosal water membrane permeability protein aquaporin 5 (AQP5), and the pathophysiology of chronic refractory sinusitis (CRS) in patients with and without nasal polyposis.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Tertiary rhinology referral center.
  
  
  METHODS
  Sinonasal samples were obtained from seven CRS subjects with nasal polyps (CRSwNP), seven CRS without nasal polyposis (CRSsNP), and five control healthy patients.
  
  
  METHODS
  Mucosal membrane changes were evaluated through hematoxylin and eosin staining of the membrane barrier and immunohistochemical staining of AQP5 expression, a membrane channel protein that affects trans-epithelial water permeability and tissue edema. AQP5 expression was confirmed by real-time PCR (rt-PCR) and western blot. Levels of other membrane proteins, including E-cadherin and Septin-2, were also assessed.
  
  
  RESULTS
  CRSwNP patients showed substantial histologic evidence of membrane remodeling with increased edema and glandular hyperplasia. The epithelial expression of AQP5 was significantly lower in CRSwNP as compared to CRSsNP or control. There was no significant difference in the expression of E-cadherin and Septin-2.
  
  
  CONCLUSIONS
  Collectively, these data suggest that the mucosal epithelial barrier is compromised in the context of CRS (predominantly in CRSwNP) when compared to control and that AQP5 acts as a key tight junction protein in the maintenance of mucosal water homeostasis. We hypothesize that AQP5 plays a possible role in the pathophysiology of mucosal edema and polyp formation.
authors.affiliation: Director, Maryland Nose & Sinus Center Rhinology Fellowship Program and of the Department of Otolaryngology-Head and Neck Surgery, Union Memorial Hospital and Sinai Hospital, Baltimore, MD, USA; Department of Otolaryngology-Head and Neck Surgery, Union Memorial Hospital, Baltimore, MD, USA. Electronic address: ashikani@aol.com.
authors.forename: Alan H
authors.initials: AH
authors.lastname: Shikani
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore.
authors.forename: Venkataramana K
authors.initials: VK
authors.lastname: Sidhaye
authors.affiliation: Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Basaraba
authors.affiliation: Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Shikani
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Mohanned A
authors.initials: MA
authors.lastname: Alqudah
authors.affiliation: Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Natalie
authors.initials: N
authors.lastname: Kirk
authors.affiliation: Center for Microbial Genetics and Genomics, Northern Arizona University; Flagstaff.
authors.forename: Emily
authors.initials: E
authors.lastname: Cope
authors.affiliation: Center for Microbial Genetics and Genomics, Northern Arizona University; Flagstaff.
authors.forename: Jeff G
authors.initials: JG
authors.lastname: Leid
mesh_terms: D051402:Aquaporin 5 / Q000032:analysis* / Q000502:physiology; D015153:Blotting, Western; D015820:Cadherins / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000032:analysis*; D009297:Nasal Mucosa / Q000737:chemistry* / Q000473:pathology; D009298:Nasal Polyps / Q000150:complications*; D011446:Prospective Studies; D012313:RNA / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D012220:Rhinitis / Q000378:metabolism*; D058112:Septins / Q000032:analysis; D012852:Sinusitis / Q000378:metabolism*
chemical_list: D051402:Aquaporin 5; D015820:Cadherins; D008565:Membrane Proteins; D012313:RNA; D058112:Septins; C407343:septin 3