IL-41: A novel serum marker correlates with disease activity in patients with ankylosing spondylitis

Interleukin (IL)-41, a type of cytokine also known as Metrnl, is involved in the pathogenesis of various inflammatory and immune-related diseases. However, its role in Ankylosing Spondylitis (AS), a field yet to be explored, remains a mystery. This study therefore assesses the diagnostic utility of IL-41 in patients with AS and examines the correlations among IL-41 levels, disease activity, and patients' demographic and clinical data. Such novel insights could have significant implications for the diagnosis and management of AS.

Eighty-eight patients diagnosed with AS were enrolled from the Rheumatology Unit at Baghdad Teaching Hospital. Participants were categorized into two groups based on disease status: inactive (n = 44) and active (n = 44). Additionally, 44 matched healthy individuals were included as controls. Comprehensive medical histories were obtained, including disease duration, body mass index, sex, and age. Laboratory parameters related to the disease-such as C-reactive protein, human leukocyte antigen (HLA-B27), and rheumatoid factor-were also measured. Serum IL-41 levels were quantified using an enzyme-linked immunosorbent assay.

The study revealed a significant difference in levels of IL-41 in patients with AS (17.721±0.705 ng/L) compared to controls (8.495±0.984 ng/L; P = 0.009). The mean serum IL-41 concentration was highest in the active group (23.037±5.268 ng/L), followed by the inactive group (12.411±1.672 ng/L; p = 0.001) and controls (8.495±0.984 ng/L). Serum IL-41 levels demonstrated strong validity for diagnosing AS, with a cutoff value of ≥ 9.35 ng/mL and an area under the curve of 0.991. The sensitivity, specificity, and accuracy were 97.7%, 79.5%, and 92.38%, respectively (p = 0.002).

IL-41 is a potential new diagnostic biomarker for AS and associated with patient's disease activity. These insights could potentially transform the way we diagnose and manage AS, offering new avenues for improved patient care and outcomes.