Interleukin-9 as a Prognostic biomarker for Systemic Lupus Erythematosus

Background: Systemic Lupus Erythematosus (SLE) is a B-cell-mediated autoimmune disease characterized by the generation of autoantibodies against nuclear antigens and a type III hypersensitivity reaction leading to chronic systemic inflammation. A cytokine called Interleukin-9 (IL-9) controls the activity of different hematopoietic cells. It was initially thought to be a cytokine made by Th2 cells. Recent findings in animal models and patient samples suggest that IL-9 plays a role in several inflammatory disorders such as Inflammatory Arthritis and SLE. Objectives: To assess if IL-9 can be used as a Prognostic biomarker for Systemic Lupus Erythematosus. Materials and Methods: In a cross-sectional study and following informed consent, 59 patients of both sexes with SLE and 26 healthy controls were included in the study. From each patient and a control 5 ml venous blood was obtained. Serum used for measurement of IL-9 and CRP using Sandwich ELISA and turbidimetric immunoassay respectively. PBMCs were used for the expression of IL-9 mRNA. Data were analyzed using SPSS and OpenEpi statistical programs. Results: The mean age of patients and controls were 27.89 ± 5.31 and 27.1 ± 5.95 years, respectively. Female: male ratio among patients was 4.4:1. Anaemia was the most frequent finding (n=34; 57%), whereas arthritis is the least (n=12; 20.3%) in patients. The mean levels of CRP in SLE patients and controls were (31.1±27.5 mg/l) and (5.8±6.7 mg/l) respectively, (p=0.01). Higher levels of serum IL-9 were indicated in patients (162.7±290.9 pg/ml) compared to controls (55.2±51.3 pg/ml), (p=0.01). The expression of IL 9 mRNA increased by more than fourfold change (4.9) due to SLE. Conclusion: The high levels of serum IL-9 and its expression as mRNA indicate that the outcome of the IL-9 level is upregulated at different levels in patients with SLE.