Plasma Osteopontin and Interleukin-18 Levels in Patients with Systemic Lupus Erythematosus: Association with Disease Activity and Lupus Nephritis
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- Category: Vol. 79, March 2011
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Plasma Osteopontin and Interleukin-18 Levels in Patients with Systemic Lupus Erythematosus: Association with Disease Activity and Lupus Nephritis,OMAR M. HERDAN, ESSAM A. ABDA and OMNIA A. MOHAMMED
Abstract
Dysregulation of cytokine production from activated T lymphocytes might play an important role in the pathogenesis and flare of SLE. Studies have reported that interleukins IL-18, IL10, IL-12, tumor necrosis factor (TNF)-alpha, osteopon-tin and interferon (IFN) gamma levels are elevated in patients with SLE, and that some of them correlated with disease activity.
Lupus nephritis (LN) occurs in more than one-third of patients with systemic lupus erythematosus. Its pathogenesis is mostly attributable to the glomerular deposition of immune complexes and overproduction of T helper-(Th-) 1 cytokines. Thus, the complex network of cytokines may contribute to the pathogenesis and activation of SLE, and an imbalance of Th1 and Th2 immune responses has been suggested to be one possible mechanism by which lupus nephritis develops and flares.
Study Design: A cross-sectional one.
Objective: The aim of our present study was to analyze the possible correlation between the plasma concentrations of OPN and IL-18 and disease activity in patients with systemic lupus erythematosus with or without renal disease. We also investigated the correlation between plasma IL-18 and OPN concentrations to further confirm the association of OPN with disease activity.
Subjects and Methods: It included 55 patients having SLE, divided into 2 groups, 30 RSLE group (28 women, 2 men, with mean age at diagnosis of 35.07±4.62yr.) and 25 SLE group (23 women, 2 men, with mean age at diagnosis of 35.84±4.74yr.), in addition to 30 age and sex matched healthy volunteers (28 women, 2 men, with mean age 36.74±4.79yr.). We measured the plasma concentration of OPN, and the plasma proinflammatory IL-18 concentration in 55 SLE patients with or without renal disease (RSLE group and SLE group, respec-tively) and in 30 sex-and age-matched controls using an enzyme linked immunosorbent assay. The disease activity was evaluated with the SLE disease activity index (SLEDAI).
Results: Plasma OPN and IL-18 concentrations were significantly higher in RSLE and SLE patients than in the controls (p=<0.000 and <0.001 respectively). Plasma OPN concentrations were significantly higher in RSLE patients than in the SLE patients (p<0.05).Plasma OPN concentration correlated positively and significantly with SLE disease activity index in RSLE patient groups (r=0.287; p=0.02). Plasma IL-18 level was positively and significantly correlated with SLEDAI score in combined SLE patient groups and in both groups with or without renal disease (r=155, p<0.05, r=287, p<0.05, r=146, p<0.05 respectively). In RSLE patients, plasma OPN concentration showed a significant positive correlation with proinflammatory cytokine IL-18 concentration (r=0.302; p=0.010).
Conclusion: This study confirmed that the circulating IL-18 and OPN concentrations were significantly elevated in SLE patients and correlated with the SLEDAI score in addition to their association with lupus nephritis. This suggests a crucial role for Th1 cytokines in the inflammatory processes and tissue damage in SLE disease. Both cytokines my act as potential marker for both lupus nephritis and monitoring SLE disease activity.