title: A multi-site study confirms abnormal glycosylation in the Tamm-Horsfall protein of patients with interstitial cystitis.
abstract: OBJECTIVE
  We confirm the single site observation of decreased sialylation and abnormal glycosylation of Tamm-Horsfall protein in patients with interstitial cystitis compared to control subjects.
  
  
  METHODS
  Urine samples from 41 controls and 48 patients with interstitial cystitis from a total of 5 North American sites were obtained in blinded fashion as to participant status. Tamm-Horsfall protein was isolated from urine samples by salt precipitation. Protein content was determined by size exclusion chromatography and normalized to creatinine. Sialic acid was quantified by 1,2-diamino-4,5-methylene dioxybenzene (Sigma®) high performance liquid chromatography with fluorescence detection. Neutral and amino sugars were determined by high pH anion exchange chromatography with pulsed amperometric detection. N-glycans were labeled with 2-aminobenzamide and profiled using high pH anion exchange chromatography with fluorescence detection. Samples were also analyzed by matrix assisted laser desorption/ionization-time of flight mass spectrometry. Permethylated N-glycans were analyzed in the mass-to-charge ratio range of 3,000 to 6,000.
  
  
  RESULTS
  There was no difference in the protein-to-creatinine ratio of Tamm-Horsfall protein from patients with interstitial cystitis vs controls (49.12 vs 46.4 mg/gm, p = 0.26). Sialic acid content (67 vs 77 nmol/mg Tamm-Horsfall protein, p = 0.025) and total monosaccharide content (590.9 vs 680.6 nmol/mg Tamm-Horsfall protein, p = 0.003) were significantly decreased in patients with interstitial cystitis vs controls. Results were supported by 2-aminobenzamide N-glycan profiling and mass spectrometry, which showed a 45% decrease in a major tetra-sialylated peak (mass-to-charge ratio 4,590) in Tamm-Horsfall protein from patients with interstitial cystitis compared to controls.
  
  
  CONCLUSIONS
  These multisite data validate that abnormal glycosylation of Tamm-Horsfall protein occurs in patients with interstitial cystitis and may have a role in interstitial cystitis causation.
authors.affiliation: Division of Urology, University of California-San Diego, San Diego, USA. cparsons@ucsd.edu
authors.forename: C Lowell
authors.initials: CL
authors.lastname: Parsons
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Proctor
authors.forename: Joel S
authors.initials: JS
authors.lastname: Teichman
authors.forename: J Curtis
authors.initials: JC
authors.lastname: Nickel
authors.forename: Edward
authors.initials: E
authors.lastname: Davis
authors.forename: Robert
authors.initials: R
authors.lastname: Evans
authors.forename: Paul
authors.initials: P
authors.lastname: Zupkas
authors.forename: Cody
authors.initials: C
authors.lastname: Phillips
authors.forename: Timothy
authors.initials: T
authors.lastname: Shaw
authors.forename: Natasha
authors.initials: N
authors.lastname: Naidu
authors.forename: Sulabha
authors.initials: S
authors.lastname: Argade
mesh_terms: D018856:Cystitis, Interstitial / Q000378:metabolism* / Q000652:urine; D006031:Glycosylation; D006801:Humans; D058949:Uromodulin / Q000378:metabolism* / Q000652:urine
chemical_list: C548612:UMOD protein, human; D058949:Uromodulin