Increased expression of omentin-1 is associated with synovitis and bone destruction in rheumatoid arthritis.

Objectives: The aberrant expression of omentin-1 had been reported in type 2 diabetes and cardiovascular disease. Here, we investigated the expression and role of omentin-1 in rheumatoid arthritis (RA).

Methods: The expression of omentin-1 in RA and in the normal population was detected by ELISA and immunohistochemistry, and collagen-induced arthritis (CIA) mice were used to detect the role of omentin-1 in RA.

Results: We found that the expression of omentin-1 was elevated in serum of RA patients compared with healthy controls (p=0.004), and in the RA disease activity group compared with the disease remission group (p<0.001). In addition, the level of omentin-1 in RA patients was positively correlated with CRP (r=0.427, p=0.002), ESR (r=0.454, p<0.001) and DAS28 (r=0.496, p<0.001; r=0.661, p<0.001, respectively). Multivariable analysis showed that omentin-1 alone was associated with disease activity state (OR=1.018, p=0.004). Immunohistochemical results showed that omentin-1 was increased in the synovium of RA and CIA mice. Omentin-1 injection resulted in an earlier onset of arthritis, an aggravated arthritic progression, more severe synovial hyperplasia and bone erosion in CIA mice. Moreover, omentin-1 treatment markedly enhanced IL-6, TNF-α, MMP-3, MMP-13 and RANKL in the joint tissue of CIA mice.

Conclusions: Our results suggested that omentin-1 was up-regulated in RA and can exacerbate synovitis and joint destruction which may provide new insight into the pathogenesis of RA.