Osteoprotegerin and receptor activator of nuclear factor-kappaB ligand mRNA expression in patients with rheumatoid arthritis and healthy controls.
OBJECTIVE
To further understand the role of osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANK-L) in rheumatoid arthritis (RA), we studied the levels of RANK-L and OPG mRNA in peripheral blood mononuclear cells (PBMC) and synovial tissue of patients with RA and controls.


METHODS
RANK-L and OPG mRNA levels were measured in PBMC and CD4+/CD8+ T cell subsets of patients with chronic RA, osteoarthritis (OA), and healthy controls, using quantitative real-time polymerase chain reaction. OPG and RANK-L mRNA levels were measured in paired blood and synovial tissue samples of patients with early, untreated RA at 2 timepoints with an interval of 16 weeks.


RESULTS
RANK-L mRNA levels were significantly higher in PBMC of patients with early and chronic RA compared to healthy controls. Contrary to healthy controls, RANK-L mRNA levels in patients with chronic RA were mainly of CD4+ T cell origin. OPG mRNA was observed in the blood of all (17/17) early RA patients, but could not be detected in chronic RA patients (0/14) or in patients with OA (0/8). Three out of 17 healthy controls showed measurable levels of OPG mRNA. The OPG/RANK-L ratio tended to be higher in the synovium than in the PBMC of early RA patients. RANK-L mRNA in synovial tissue was mainly of non-T cell origin.


CONCLUSIONS
Since RANK-L and OPG mRNA levels are elevated in PBMC of RA patients, and CD4+ T cells are the major contributors to RANK-L mRNA expression, mononuclear cells in patients with RA may be involved in the pathways that regulate bone metabolism.
Vanderborght
Ann
A
Limburgs Universitair Centrum, Biomedisch Onderzoeksinstituut, Diepenbeek, Belgium.
Linsen
Loes
L
Thewissen
Mariëlle
M
Geusens
Piet
P
Raus
Jef
J
Stinissen
Piet
P
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D002352:Carrier Proteins; D016022:Case-Control Studies; D005260:Female; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008562:Membrane Glycoproteins; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger / Q000378:metabolism*; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D018124:Receptors, Tumor Necrosis Factor; D013583:Synovial Membrane / Q000378:metabolism
D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human