title: The imbalance between osteoprotegerin and cathepsin K in the serum of patients with longstanding rheumatoid arthritis.
abstract: Osteoprotegerin (OPG) and soluble receptor activator of NF-kappa B ligand (sRANKL) together regulate the bone metabolism among other cytokines, whereby cathepsin K has a potent collagen-degrading activity. An imbalance of this system may be partly responsible for the skeletal complications of RA. Expanding on a previous study, we investigated the relationship between OPG, sRANKL and cathepsin K levels in the serum of patients with longstanding RA. We measured serum levels of OPG, sRANKL and cathepsin K of 100 patients with active, longstanding RA. We detected elevated serum levels of cathepsin K (median 54.8 pmol/l) and OPG (median 4.8 pmol/l), but normal sRANKL levels (median 0.2 pmol/l). Cathepsin K did not show a correlation with the overexpressed OPG (P=0.64) and sRANKL (P=0.81). The radiological destruction correlates significantly with cathepsin K (P=0.004) and OPG (P=0.007). We speculate that the increased levels of OPG are effective in compensating the action of sRANKL, but do not directly prevent bone degradation, as reflected by the elevated serum levels of cathepsin K.
authors: Institute of Rheumatology of the Kurstadt Baden in Cooperation with the Danube University Krems, Baden, Austria. martin.skoumal@wgkk.sozvers.at
authors: Martin
authors: M
authors: Skoumal
authors: Günther
authors: G
authors: Haberhauer
authors: Gernot
authors: G
authors: Kolarz
authors: Gerhard
authors: G
authors: Hawa
authors: Wolfgang
authors: W
authors: Woloszczuk
authors: Anton
authors: A
authors: Klingler
authors: Franz
authors: F
authors: Varga
authors: Klaus
authors: K
authors: Klaushofer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy; D015415:Biomarkers; D056657:Cathepsin K; D002403:Cathepsins / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D053244:Osteoprotegerin / Q000097:blood*; D053245:RANK Ligand / Q000097:blood
chemical_list: D015415:Biomarkers; D053244:Osteoprotegerin; D053245:RANK Ligand; D002403:Cathepsins; C534130:CTSK protein, human; D056657:Cathepsin K