title: Effects of tiaprofenic acid on urinary pyridinium crosslinks in adjuvant arthritic rats: comparison with doxycycline.
abstract: OBJECTIVE
  To study the effects of tiaprofenic acid and doxycycline on urinary pyridinium crosslinks and paw swelling in adjuvant arthritic rats, and to gain additional information on the drugs' inhibitory potential vs. in vitro targets, such as enzyme activity of matrix metalloproteinases and cytokine generation.
  
  
  METHODS
  124 male Wistar Lewis rats; for the in vitro studies human matrix metalloproteinases and human mononuclear cells were used.
  
  
  METHODS
  Arthritis was induced by injection of complete Freund adjuvant. Drugs (2, 15, 50 mg tiaprofenic acid/kg; 5, 15, 30 mg doxycycline/kg) were administered daily p.o. until day 21. In the in vitro studies 10-1000 mumoles/l of these drugs were used.
  
  
  METHODS
  Urinary levels of pyridinoline and deoxypyridinoline, determined by HPLC/fluorescence, and paw volumes were the measurements in the rat study. In the in vitro studies enzyme activities were assessed using fluorogenic peptide substrates; cytokines were determined by ELISA.
  
  
  RESULTS
  On day 21 of disease crosslink excretion was about twofold higher compared to the healthy controls. After administering daily 15 or 30 mg/kg tiaprofenic acid p.o. this increase was almost completely prevented whereas the paw volumes were suppressed by about 50%. Up to 50 mg/kg doxycycline did not display significant suppressive effects on crosslinks and paw volumes. In vitro 50-100 mumol/l of both drugs inhibited the activities of selected metallo-proteinases, but only doxycycline suppressed the generation of IL-1 beta/TNF alpha in human mononuclear cells, whereas tiaprofenic acid was virtually inactive in that model.
  
  
  CONCLUSIONS
  In arthritic rats tiaprofenic acid has not only the capability to suppress paw inflammation, but also to prevent with high potency the excretion of pyridinium crosslinks. Doxycycline without inherent antiinflammatory activity does not exhibit such preserving effects on collagen degradation in this model. Thus the mode of action of cartilage protecting drugs within the complex pathogenesis of arthritis will need further elucidation.
authors.affiliation: Hoechst AG, Wieshaden, Germany. weithmann@msmlrf.hoechst.com
authors.forename: K U
authors.initials: KU
authors.lastname: Weithmann
authors.forename: V
authors.initials: V
authors.lastname: Schlotte
authors.forename: V
authors.initials: V
authors.lastname: Jeske
authors.forename: D
authors.initials: D
authors.lastname: Seiffge
authors.forename: A
authors.initials: A
authors.lastname: Laber
authors.forename: B
authors.initials: B
authors.lastname: Haase
authors.forename: R
authors.initials: R
authors.lastname: Schleyerbach
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology*; D001169:Arthritis, Experimental / Q000188:drug therapy* / Q000473:pathology / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004318:Doxycycline / Q000008:administration & dosage / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005620:Freund's Adjuvant; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors; D011422:Propionates / Q000008:administration & dosage / Q000494:pharmacology*; D011726:Pyridinium Compounds / Q000652:urine*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003432:Cross-Linking Reagents; D016207:Cytokines; D011422:Propionates; D011726:Pyridinium Compounds; C021270:tiaprofenic acid; D005620:Freund's Adjuvant; D008666:Metalloendopeptidases; D004318:Doxycycline