Blockade of Wnt-5A/frizzled 5 signaling inhibits rheumatoid synoviocyte activation.
OBJECTIVE
It is not understood why cultured fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) often display a persistently activated phenotype, despite removal from an inflammatory environment. Previously, we found that these FLS expressed high levels of both Wnt-5A and Frizzled 5 (Fz5), a receptor-ligand pair implicated in both limb bud and bone marrow stem cell development. The objective of the present experiments was to determine whether Wnt-5A/FzS signaling contributes to FLS activation.


METHODS
Wnt-5A expression in FLS was inhibited by transfection with both antisense and dominant negative (dn) vectors. Fz5 signaling was blocked with an antibody to the extracellular domain of the receptor. The effects of these treatments on the expression of the proinflammatory cytokines interleukin-6 (IL-6) and IL-15 and on the expression of receptor activator of nuclear factor kappaB ligand (RANKL) were assessed by reverse transcriptase-polymerase chain reaction and immunoblotting.


RESULTS
Both antisense Wnt-5A and dnWnt-5A vectors, but not empty vector, diminished IL-6 and IL-15 expression in RA FLS. Anti-Fz5 antibody exerted similar effects and also reduced RANKL expression.


CONCLUSIONS
Wnt-5A/Fz5 signaling may contribute to the activated state of FLS in RA. Receptor antagonists of Fz5 should be considered for the treatment of refractory synovitis.
Sen
M
M
Department of Medicine, University of California, San Diego, La Jolla 92093-0663, USA.
Chamorro
M
M
Reifert
J
J
Corr
M
M
Carson
D A
DA
D019138:Antibodies, Blocking / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D016373:DNA, Antisense / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000378:metabolism; D051157:Frizzled Receptors; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D019409:Interleukin-15 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D053245:RANK Ligand; D012333:RNA, Messenger / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter / Q000037:antagonists & inhibitors / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism*; D014162:Transfection; D051153:Wnt Proteins; D000071818:Wnt-5a Protein
D019138:Antibodies, Blocking; D002352:Carrier Proteins; D016373:DNA, Antisense; C498589:FZD5 protein, human; D051157:Frizzled Receptors; D019409:Interleukin-15; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein