Rituxan (rituximab) is a genetically engineered chimeric murine/human monoclonal IgG1 kappa antibody directed against the CD20 antigen. RA pathology is influenced by Interleukin-20 serum levels as shown in this research. The rituximab therapy was found to be favorable for either the seropositive and seronegative RA patients.

Interleukin 20 (IL-20), a member of IL-10 cytokine family, is a pleiotropic cytokine promoting inflammation, angiogenesis, chemotaxis and is implicated in the pathogenesis of rheumatoid arthritis (RA). In this study, serum levels of IL-20 were analysed in relation to disease activity and response to therapy in active patients with established RA who started biologic therapy with rituximab (RTX).

 IL-20 serum levels were analysed in 27 RA patients (24 females) at baseline and after 16 weeks of treatment; and in 49 age- and sex-matched healthy individuals. RA disease activity at baseline and after the treatment was assessed using DAS-28, CRP levels, erythrocyte sedimentation rate (ESR), total swollen joint count (SJC) and tender joint count (TJC). IL-20 serum concentrations were analysed by ELISA.

Baseline levels of IL-20 were significantly higher in RA patients compared to healthy individuals [73.54 (38.69–172.0) vs. 27.55 (15.42–72.92) pg/ml, p < 0.0024] and decreased after 16 weeks of RTX therapy [from 73.54 (38.69–172.0) to 61.94 (31.48–103.8) pg/ml, p = 0.040]. When analysed separately according to presence of autoantibodies, the decrease in IL-20 after RTX therapy was significant only in seropositive (RF+ and ACPA+, N = 20) patients [from 75.11 (44.70–180.9) to 61.94 (31.48–103.8), p = 0.043], but not in seronegative patients [from 51.53 (7.25–107.8) to 63.35 (23.30–102.9), p = 0.625]. Moreover, baseline IL-20 levels significantly correlated with DAS28 (r = 0.491, p = 0.008), CRP (r = 0.507, p = 0.006), ESR (r = 0.422, p = 0.025) and SJC (r = 0.376, p = 0.049).

Circulating IL-20 levels are higher in RA patients compared to healthy individuals, correlate with disease activity and decrease in response to RTX therapy in seropositive patients. Based on these data, it can be speculated that IL-20 plays a role in RA pathology and is influenced by B cell depleting therapy.