Assessment Levels of IL-22 in Rheumatoid Arthritis Patients in Najaf City

Abstract

Rheumatoid arthritis (RA) is a chronic, T cell–driven autoimmune disease characterized by persistent synovial inflammation, joint pain, swelling and stiffness, and often leads to structural deformities. Beyond the joints, RA may involve extra-articular organs such as the heart, lungs, kidneys and digestive tract, contributing to considerable morbidity. In this study, we sought to explore the role of interleukin-22 (IL-22)—a cytokine primarily produced by activated T cells—in RA by comparing its serum levels in patients and healthy volunteers alongside established immunological markers. We conducted a case–control study in which venous blood was drawn from two groups: 30 patients meeting the 2010 ACR/EULAR criteria for RA and 30 age- and sex-matched healthy controls. Serum IL-22 and anti–cyclic citrullinated peptide (anti-CCP) antibody concentrations were measured by enzyme-linked immunosorbent assay (ELISA), while rheumatoid factor (RF) IgM and C-reactive protein (CRP) levels were determined using the I-Chroma system. Statistical analyses employed Student’s t-test for continuous variables and chi-square test for proportions, with p < 0.05 considered significant. Patients with RA exhibited a mean serum IL-22 level of 173.9 ± 51.2 pg/mL, which was significantly lower than the 216.3 ± 84.6 pg/mL observed in healthy controls (p = 0.001). RF IgM positivity was more frequent in the RA group (43.3%) compared with controls (13.3%, p = 0.005), and CRP levels were markedly elevated in RA patients (14.90 ± 7.17 IU/dL) versus controls (4.58 ± 1.50 IU/dL, p < 0.001).