T Regulatory Cells in Rheumatoid Arthritis with Reference to Anti-Citrullinated Peptide Antibody and TNF-alpha Inhibitor Therapy

Abstract

T regulatory cells (Tregs) plays an important role in maintaining self-tolerance and preventing autoimmune diseases by inhibiting proliferation and cytokine production of self-reactive T cells. Controversy was reported regarding the frequency of CD4+CD25+ Tregs in the peripheral circulation of rheumatoid arthritis (RA) patients compared to normal controls. Also, some showed that treatment with TNF-α inhibitor restored the capacity of Tregs. This work aimed to study Tregs in the peripheral blood of RA patients versus control in addition to those on TNF-α inhibitor therapy compared to those who have not received it and to correlate with status of anti-cyclic citrullinated peptide antibody (ACPA). Two groups of RA patients were studied; one on TNF-α inhibitor therapy and the other not. Additionally, age-matched apparently healthy controls were studied. The percentage of CD4+CD25+ T cells in the total lymphocytic cell population was determined by flow cytometry analysis while ACPA concentration was measured by a second-generation peptide-based ELISA. Mean level of Tregs was significantly lower in the studied RA patients compared to the control group. Patients in early disease (0-5 years) had low mean Tregs percentage compared to patients with long duration of disease (> 10 years) (P=0.044). Patients on TNF-α blocker therapy had elevated Tregs percentage relative to patients on methotrexate (MTX) (P=0.022) and other therapies. No effect of gender or age was found on Tregs levels. In RA patients, 85.4% were ACPA seropositive and 65.9% of seropositive patients have concentration of > 100U/ml. The mean Treg percentage was significantly lower in ACPA seronegative group compared to the seropositive group (P=0.013). In conclusion, the studied RA patients have low Treg, and TNF-α blocker therapy increased its number, compared to other therapies.