Evaluating The Correlation between Level of Serum Interleukin-9 and Disease Activity in Chronic Spontaneous Urticaria Patients

Chronic spontaneous urticaria (CSU) is a common dermatological disease, estimated to occur in 0.5% to 5% of the general population, with an annual incidence rate of approximately 1.4%. Chronic spontaneous urticaria is diagnosed when the patient has wheals with or without angioedema for longer than six weeks. The patient's symptoms may be caused by known factors (such as mast cell-activating autoantibodies) or unknown factors. Aim of the work: Our study aimed to measure the association between IL-9 and CSU severity, in order to help improving knowledge about CSU management and prognosis. Patients & methods: A case-control study was carried out from September 2024 to March 2025 at the dermatology outpatient clinics of Mansoura University, from people enrolled in the hospital registry. A total of 43 patients diagnosed with chronic spontaneous urticaria who met the inclusion criteria were enrolled in the study. Additionally, 43 age- and sex-matched healthy controls were included. Venous blood samples were collected from both the case and control groups, and serum IL-9 levels were measured using the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Disease activity in the case group was assessed using the Urticaria Activity Score over seven days (UAS7). Statistical analysis included correlation tests, odds ratio calculations, and subgroup comparisons. Conclusion: We conclude that According to the analysis, CSU patients' IL-9 levels were statistically significantly higher than those of healthy controls. These findings suggest IL-9 may play a contributory role in CSU pathogenesis and could be considered a potential biomarker of disease activity.