Background The cold-inducible RNA-binding protein (CIRP) is 18 kDa protein of the glycine-rich RNA binding protein (GRP) family, and these proteins function as RNA chaperones to facilitate translation. Extracellular CIRP is a recently identified endogenous proinflammatory mediator and damage-associated molecular pattern molecules (DAMP) that triggers inflammatory responses in sepsis and inflammatory bowel disease.

Objectives This study was planned to investigate the relationship between CIRP and rheumatoid arthritis.

Methods Peripheral blood and synovial fluid were collected from 15 patients with rheumatoid arthritis (RA) and 16 patients with osteoarthritis (OA). The concentration of CIRP was measured by sandwich Enzyme-Linked Immunosorbent Assay (ELISA).

Results The concentration of serum CIRP was significantly elevated in RA patients group (RA patients=26.39±10.48 pg/ml, OA patients=17.14±7.24 pg/ml, p=0.009). Furthermore, the RA patients group showed significantly higher CIRP concentration than the OA patients group in synovial fluid (153.56±108.93 pg/ml vs. 23.63±16.18 pg/ml, p<0.001) (Fig.1).

The mean concentration of synovial fluid CIRP was significantly higher than that of serum in RA patients group (Serum concentration=26.39±10.48 pg/ml, Synovial fluid=153.56±108.93 pg/ml, p<0.001). Also, we found the tendency that the CIRP concentration of synovial fluid was significantly higher than that of serum in same patient (P=0.025) (Fig.2).

DAS28-ESR and DAS28-CRP were positively correlated with synovial fluid concentration of CIRP (DAS28-ESR: r=0.582, p=0.023, DAS28-CRP: r=0.541, p=0.037, by correlation analysis).

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Conclusions The serum and synovial concentration of CIRP in RA patients was increased compared to OA patients. Also synovial concentration of CIRP in RA patients correlated well with the disease activity, i.e. the DAS28-ESR/CRP. Based on these results, the CIRP mediates the inflammation and is potential marker for synovial inflammation.

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Disclosure of Interest None declared