LXR modulation blocks prostaglandin E2 production and matrix degradation in cartilage and alleviates pain in a rat osteoarthritis model.
Osteoarthritis (OA), the most common arthritic condition in humans, is characterized by the progressive degeneration of articular cartilage accompanied by chronic joint pain. Inflammatory mediators, such as cytokines and prostaglandin E(2) (PGE(2)) that are elevated in OA joints, play important roles in the progression of cartilage degradation and pain-associated nociceptor sensitivity. We have found that the nuclear receptor family transcription factors Liver X Receptors (LXRalpha and -beta) are expressed in cartilage, with LXRbeta being the predominant isoform. Here we show that genetic disruption of Lxrbeta gene expression in mice results in significantly increased proteoglycan (aggrecan) degradation and PGE(2) production in articular cartilage treated with IL-1beta, indicating a protective role of LXRbeta in cartilage. Using human cartilage explants, we found that activation of LXRs by the synthetic ligand GW3965 significantly reduced cytokine-induced degradation and loss of aggrecan from the tissue. Furthermore, LXR activation dramatically inhibited cytokine-induced PGE(2) production by human osteoarthritic cartilage as well as by a synovial sarcoma cell line. These effects were achieved at least partly by repression of the expression of ADAMTS4, a physiological cartilage aggrecanase, and of cyclooxygenase-2 and microsomal prostaglandin E synthase-1, key enzymes in the PGE(2) synthesis pathway. Consistent with our in vitro observations, oral administration of GW3965 potently alleviated joint pain in a rat meniscal tear model of osteoarthritis.
Li
Ning
N
Pfizer BioTherapeutics Research, Cambridge, MA 02140, USA.
Rivéra-Bermúdez
Moisés A
MA
Zhang
Mei
M
Tejada
Julio
J
Glasson
Sonya S
SS
Collins-Racie
Lisa A
LA
Lavallie
Edward R
ER
Wang
Yihe
Y
Chang
Ken C N
KC
Nagpal
Sunil
S
Morris
Elisabeth A
EA
Flannery
Carl R
CR
Yang
Zhiyong
Z
D051722:ADAM Proteins / Q000037:antagonists & inhibitors; D000071121:ADAMTS4 Protein; D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D002358:Cartilage, Articular / Q000378:metabolism*; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors; D008024:Ligands; D000071518:Liver X Receptors; D051379:Mice; D008817:Mice, Mutant Strains; D057093:Orphan Nuclear Receptors / Q000819:agonists* / Q000235:genetics / Q000502:physiology; D010003:Osteoarthritis / Q000150:complications* / Q000378:metabolism; D010146:Pain / Q000209:etiology / Q000378:metabolism*; D011348:Procollagen N-Endopeptidase / Q000037:antagonists & inhibitors; D000071876:Prostaglandin-E Synthases; D051381:Rats
D001565:Benzoates; D001596:Benzylamines; C473027:GW 3965; D008024:Ligands; D000071518:Liver X Receptors; C000605213:NR1H3 protein, human; C000605214:Nr1h3 protein, mouse; C000605215:Nr1h3 protein, rat; D057093:Orphan Nuclear Receptors; D051546:Cyclooxygenase 2; D051722:ADAM Proteins; D011348:Procollagen N-Endopeptidase; D000071121:ADAMTS4 Protein; C000603918:ADAMTS4 protein, human; C000603919:Adamts4 protein, mouse; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone