Study of serum interleukin-35 as a predictive biomarker in lupus nephritis

Background Systemic lupus erythematosus (SLE) is a classic autoimmune disorder where the immune system produces antibodies against the cell component, leading to a wide range of clinical symptoms. Interleukin-35 (IL-35) is a cytokine that is predominantly secreted by T-regulatory cells and has anti-inflammatory and immunosuppressive roles. Aim To determine whether serum IL-35 could be used to assess renal involvement in SLE patients without invasive procedures. Patients and methods The current research included 60 age-matched and sex-matched patients, who were categorized into three groups: group I ( n =20): healthy individuals serving as control, group II ( n =20): SLE patients without nephritis, and group III ( n =20): SLE patients with nephritis. Serum IL-35 was measured using enzyme-linked immunosorbent assay technique. Results Serum IL-35 levels were considerably greater in SLE patients with nephritis than those without nephritis and the control group ( P =0.001). There were significant positive correlations between IL-35 and ESR, protein/creatinine ratio, SLE disease activity index score, urea, and creatinine ( P <0.05). The receiver operating characteristics curve concerning serum IL-35 demonstrated a sensitivity of 96% and a specificity of 91% to differentiate lupus nephritis patients from SLE patients without nephritis. Conclusion Serum IL-35 levels were significantly higher in SLE patients compared to the control group. Since a high level of IL-35 was detected in nephritis patients with SLE, it is thought to play a role in the diagnosis of lupus nephritis. The substantial association between serum IL-35 and the SLE disease activity index score, and other lupus flare markers suggested that it is involved in lupus activity.