Assessment the Levels of Toll-Like Receptor 4 (TLR4) in Patients with Rheumatoid Arthritis in Al-Najaf City

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent synovial inflammation that ultimately leads to joint destruction. Although serological markers such as rheumatoid factor (RF) and C-reactive protein (CRP) are routinely used in diagnosis and monitoring, there remains a need for more sensitive and specific biomarkers—particularly for early disease detection and assessment of activity. Objective: To evaluate whether serum Toll-like receptor 4 (TLR4) levels differ between RA patients and healthy controls, and to compare the diagnostic performance of TLR4 with established biomarkers (anti-cyclic citrullinated peptide [anti-CCP], RF IgM, and CRP). Methodology: A case–control study was conducted with 60 clinically diagnosed RA patients (9 males, 51 females) and 60 age- and sex-matched healthy volunteers (20 males, 40 females). Serum RF IgM and CRP concentrations were measured using the I-Chroma™ immunoassay reader. Anti-CCP and TLR4 levels were quantified via sandwich ELISA (Bioassay Technology Laboratory, Shanghai, China). Statistical comparisons between groups were performed using Student’s t-test or χ² test as appropriate, with significance set at P<0.05. Results: Mean serum TLR4 concentrations were comparable between RA patients and healthy controls (2.43 ± 0.74 pg/mL vs. 2.50 ± 0.64 pg/mL; p = 0.58), indicating no significant difference. In contrast, anti-CCP antibodies were detected in 96.7% of patients but in none of the controls (p < 0.001), underscoring its strong diagnostic specificity. Rheumatoid factor IgM was positive in 43.3% of patients compared with 13.3% of controls (p = 0.005). Although mean CRP levels were higher in the patient group (14.90 ± 30.17 mg/L) than in the control group (12.28 ± 14.32 mg/L), this elevation did not reach statistical significance (p = 0.55). Conclusion: TLR4 serum concentrations do not differ significantly between RA patients and healthy individuals, suggesting limited utility as a standalone biomarker. In contrast, anti-CCP exhibits strong discriminatory power and remains the most reliable serological marker for RA diagnosis and disease activity assessment.