Serum interleukin-18 levels in patients with systemic lupus erythematosus: Relation with disease activity and lupus nephritis

Aim of the workTo further investigate the possible role of IL-18 in the pathogenesis of systemic lupus erythematosus (SLE) and development of lupus nephritis (LN), and to explore its relationship with pathological classes of LN, degree of acute renal activity and chronic damage.Patients and methodsForty-one SLE patients with LN, thirty-one lupus non-nephritis patients and fifteen age and sex matched healthy controls were enrolled in this study. SLE patients were subjected to disease activity assessment by SLEDAI, renal disease activity assessment by the Systemic Lupus International Collaborating Clinics (SLICC) Renal Activity Score, laboratory investigations including measurement of serum interleukin-18 using Enzyme Linked Immunosorbent Assay. Renal biopsy was obtained from LN patients and pathological classification was made according to World Health Organization (WHO) criteria. Analysis of activity and chronicity indices was done on these biopsy specimens.ResultsSerum levels of IL-18 were significantly higher in patients with LN than lupus non-nephritis patients and healthy controls (p < 0.001). There were significant correlations between IL-18 and SLEDAI (p = 0.002), proteinuria (p = 0.027), renal activity score (p = 0.003) and activity index (p = 0.039) in patients with LN. There was no significant difference in the serum levels of IL-18 between WHO classes of LN.ConclusionIL-18 appears to have a pathogenic role in the development of SLE and plays a crucial role in triggering inflammation in LN. Serum IL-18 levels could be a useful biomarker to assess the activity of renal disease in SLE.