Serum level of interleukin-11 in patients with rheumatoid arthritis; relation to disease activity and interstitial lung disease

Rheumatoid arthritis is a complex autoimmune disease characterized by local and systemic inflammation. The purpose of this study was to assess serum level of circulating interleukin-11 in rheumatoid arthritis cases and to estimate its correlation with clinical and laboratory parameters of rheumatoid arthritis disease, especially interstitial lung disease and disease activity. This was a case-control study carried out on sixty rheumatoid arthritis patients who were divided into two groups: thirty rheumatoid arthritis patients without interstitial lung disease and thirty rheumatoid arthritis patients with interstitial lung disease. The patients were classified according to the criteria for rheumatoid arthritis and were recruited from the outpatient and inpatient department of Rheumatology and Rehabilitation between June 2023 to February 2024. Thirty healthy participants were also included as control. There was a statistically significant higher level of interleukin-11 among rheumatoid arthritis patients, both with interstitial lung disease and non-interstitial lung disease, compared to healthy controls (P-value less than 0.001). However, the difference between the interstitial lung disease and non-interstitial lung disease groups was statistically insignificant (p-value greater than 0.05). Similarly, the association between interstitial lung disease type and interleukin-11 level in the interstitial lung disease group was not significant (P-value > 0.05). Interleukin-11 levels had a significant role in detecting rheumatoid arthritis (compared to controls) at a cut-off value of 32.7 pg/mL, with a sensitivity of 96.67% and a specificity of 60%, a positive predictive value of 82.4%, and a negative predictive value of 81.8%. Interleukin-11 is highly elevated in both rheumatoid arthritis without interstitial lung disease and rheumatoid arthritis with interstitial lung disease but did not differentiate between them. This suggests that interleukin-11 is involved in the inflammatory process of both articular and extra-articular manifestations. However, in the absence of a correlation between the disease activity score for the twenty-eight-Joints and interleukin-11, further research is needed to understand its role in etiopathogenesis.