To measure the levels of Tumor necrosis factor (TNF)-like ligand 1A (TL1A) and decoy receptor 3 (DcR3) in serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA). To evaluate the effect of recombinant human (rh) TL1A on interleukin (IL)-17 production and IL-17mRNA expression.
The serum and SF levels of TL1A and DcR3, and the production of IL-17 by rhTL1A-treated PBMC were measured by enzyme-linked immunosorbent assay (ELISA). The expression of IL-17 mRNA by rhTL1A-treated PBMC was measured by real-time reverse transcriptase polymerase chain reaction (RT-PCR). We also tested the change of TL1A and DcR3 level following TNF-α blockade therapy.
Serum TL1A and DcR3 levels were higher in RA patients. This increase was more significant in RF and anti-CCP positive patients. TL1A and DcR3 levels were higher in SF samples than in paired sera. TL1A and DcR3 decreased after anti-TNF treatment. rhTL1A increased the production of IL-17 protein and the expression of IL-17mRNA.
TL1A and DcR3 may be of pathogenic and potentially of therapeutic importance in RA patients.