Association Between Serum Interleukin-6 Level in Obese and Non-Obese Rheumatoid Arthritis

Abstract

Background: Rheumatoid arthritis (RA) is a chronic and progressive autoimmune disorder characterized by inflammation that affects every system in the body.

Objectives: A study aimed to investigate the association between serum interleukin-6 levels in sera of non-obese RA and compared with that in obese RA of Iraqi women.

Materials and Methods: A case-control study design was utilized to collect data from 130 participants between October 2023 and March 2024, aged 35 to 65. Five mL were withdrawn from patients who visited the joint consultation at Imam Hassan Al-Mujtaba Hospital. The SMART-120 chemical analyzer (AFLO/Germany, colorimetric enzymatic method) was utilized to quantify the amounts of total cholesterol (TC), triglycerides (TG), high-density cholesterol (HDL-C), and low-density cholesterol (LDL-C) in human serum. Additionally, the ELISA technique (UNO/HUMAN/Germany) was used to evaluate the levels of serum IL-6.

Results: The study found a significant increase in serum IL-6 levels in (obese and non-obese) RA patients when compared with control group (71.02 ± 11.39 pg/ml), (59.85 ± 14.50 pg/ml), and (5.87 ± 1.91 pg/ml, P < 0.0001) respectively. The receiver-operating curve (ROC) study for IL-6 in non-obese RA revealed a sensitivity of 69%, specificity of 73%, 95% confidence interval (CI) ranging from 0.684 to 0.887, and an area under the curve (AUC) of 0.785. The cut-off point was set at 51.52 pg/ml or above. In the obese RA group, IL-6 had AUC with a value of 0.945 [95% CI (confidence interval) =0.899– 0.991, Sensitivity = 91%, Specificity = 83%, Cut-off point = 54.35 pg /mL].

Conclusion: Elevated serum IL-6 levels in non-obese and obese RA patients suggest an important role in autoimmune disorders in RA and are considered as a biomarker for pro-inflammatory for assessing RA and obesity.