title: Diacerhein and rhein reduce the ICE-induced IL-1beta and IL-18 activation in human osteoarthritic cartilage.
abstract: OBJECTIVE
  IL-1beta plays a fundamental role in osteoarthritis (OA) pathophysiology and cartilage destruction. Targeting the activation mechanism of this cytokine appears to be important as a therapeutic approach. As the interleukin-1 converting enzyme (ICE) is the physiologic modulator of the production of active IL-1beta, we investigated the effect of diacerhein and its active metabolite rhein used in the treatment of OA patients, on the enzyme expression and synthesis on human OA cartilage. Further, we looked at the effect of both drugs on the production of the active form of IL-1beta and IL-18.
  
  
  METHODS
  The expression and synthesis of ICE were investigated on human OA cartilage explants using in-situ hybridization and immunohistochemical methods, respectively. The effect of the drugs on ICE OA chondrocytes was also determined by Northern blotting and a specific ELISA assay. Furthermore, the effect of both drugs on the level of active IL-1beta and IL-18 was examined by immunohistochemistry.
  
  
  RESULTS
  Data showed that diacerhein and rhein have no true effect on reducing total ICE mRNA by both Northern blotting analysis and in-situ hybridization. A marked and statistically significant decrease was, however, found for protein production. ELISA showed a reduction of 31% (P< 0.04) for diacerhein and 50% (P< 0.02) for rhein. The drugs' immunohistological cell score reduction was similar to data from the ELISA, and a statistical significant reduction of ICE production was found at both superficial and deep zones of the cartilage. IL-1beta and IL-18 were both preferentially produced in chondrocytes of the superficial zone. For each of these cytokines, both drugs demonstrated a statistically significant decrease in this zone. A marked decrease was also noted in the deep zone, but statistical significance was reached only for rhein.
  
  
  CONCLUSIONS
  These results provide a novel regulatory mechanism by which diacerhein and rhein could exert a down-regulation on IL-1's effect on OA cartilage.
authors.affiliation: Osteoarthritis Research Unit, Centre hospitalier de l'Université de Montréal (CHUM), Hôpital Notre-Dame, Montréal, Québec, H2L 4M1, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Moldovan
authors.forename: J P
authors.initials: JP
authors.lastname: Pelletier
authors.forename: F C
authors.initials: FC
authors.lastname: Jolicoeur
authors.forename: J M
authors.initials: JM
authors.lastname: Cloutier
authors.forename: J
authors.initials: J
authors.lastname: Martel-Pelletier
mesh_terms: D000880:Anthraquinones / Q000494:pharmacology*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D015152:Blotting, Northern; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects; D020170:Caspase 1 / Q000187:drug effects / Q000235:genetics / Q000494:pharmacology*; D019902:Chondrocytes / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D007375:Interleukin-1 / Q000502:physiology*; D020382:Interleukin-18 / Q000502:physiology*; D008297:Male; D010003:Osteoarthritis / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects
chemical_list: D000880:Anthraquinones; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D020382:Interleukin-18; D012333:RNA, Messenger; C025292:diacerein; D020170:Caspase 1; C020491:rhein