TIPE2 expression is increased in peripheral blood mononuclear cells from patients with rheumatoid arthritis

We investigated the changes in mRNA and protein expression of tumor necrosis factor-α–induced protein 8-like 2 (TIPE2) and PEST-containing nuclear protein (PCNP) in peripheral blood lymphocytes from 54 patients with rheumatoid arthritis (RA) and the spleens of model mice with collagen-induced arthritis (CIA) to generate new ideas for clinical diagnosis and treatment. Expression levels of both TIPE2 and PCNP were higher in RA patients and CIA mice than in their respective controls. They were also higher in the 32 patients with active RA than in the 22 with inactive RA (P < 0.001 for both). After comprehensively treating patients with active RA with anti-inflammatory and antirheumatic drugs for 6 months, they were stable, and there was no difference in TIPE2 levels between the treated patients and those with inactive RA (P = 0.85). In addition, TIPE2 mRNA levels in peripheral blood correlated positively with PCNP (R(2) = 0.744, P = 0.001). The DAS28 score correlated positively with peripheral blood TIPE2 levels in the RA patients (R(2) = 0.945, P = 0.001). These findings suggest TIPE2 expression increases with the severity of RA.