Effects of anti-arthritis preparations on gene expression and enzyme activity of cyclooxygenase-2 in cultured equine chondrocytes.
OBJECTIVE
To determine the effects of recombinant equine interleukin -1beta (reIL-1beta) and 4 anti-inflammatory compounds on the expression and activity of cyclooxygenase (COX)-2 in cultured equine chondrocytes.


METHODS
Articular cartilage from 9 young adult horses.


METHODS
Reverse transcriptase-polymerase chain reaction methods were used to amplify a portion of equine COX-2 to prepare a cDNA probe. Northern blot analysis was used to quantify the expression of COX-2 in first-passage cultures of equine articular chondrocytes propagated in media containing dexamethasone (DEX), phenylbutazone (PBZ), polysulfated glycosaminoglycan, and hyaluronan, each at concentrations of 10 and 100 microg/ml and each with or without reIL-1beta. A commercial immunoassay was used to determine prostaglandin E2 (PGE2) concentrations in conditioned medium of similarly treated cells to quantify COX-2 activity.


RESULTS
Addition of reIL-1beta increased the expression of COX-2 in a dose-dependent manner, which was paralleled by an increased concentration of PGE2 in culture medium. Concentration of PGE2 in spent medium from reIL-beta-treated chondrocytes was significantly reduced by DEX and PBZ; however, only DEX significantly reduced gene expression of COX-2.


CONCLUSIONS
Prostaglandin E2 is considered to be an important mediator in the pathophysiologic processes of arthritis, and cultured chondrocytes respond to interleukin-1 with enhanced expression and activity of COX-2. Palliative relief in affected horses is probably attributable, in part, to inhibition of PGE2 synthesis; however, analysis of these data suggests that of the 4 compounds tested, only DEX affects pretranslational regulation of the COX-2 gene in cultured equine chondrocytes.
Tung
Jayne T
JT
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
Venta
Patrick J
PJ
Eberhart
Susan W
SW
Yuzbasiyan-Gurkan
Vilma
V
Alexander
Lee
L
Caron
John P
JP
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000009:adverse effects / Q000494:pharmacology*; D015152:Blotting, Northern; D002358:Cartilage, Articular / Q000166:cytology; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology* / Q000502:physiology; D051546:Cyclooxygenase 2; D003907:Dexamethasone / Q000494:pharmacology; D015232:Dinoprostone / Q000096:biosynthesis / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D006025:Glycosaminoglycans / Q000494:pharmacology; D006736:Horses / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D010653:Phenylbutazone / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
D000893:Anti-Inflammatory Agents; D006025:Glycosaminoglycans; D007375:Interleukin-1; D007527:Isoenzymes; C013786:A73025; D012313:RNA; D003907:Dexamethasone; D006820:Hyaluronic Acid; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D010653:Phenylbutazone; D015232:Dinoprostone