The role of Dickkopf-1 as a biomarker in systemic lupus erythematosus and active lupus nephritis

Abstract

Systemic lupus erythematosus (SLE) is a chronic disease which is mainly attributed to autoantibodies, cytokines, and immune complex deposition. Studies have demonstrated that cytokines and autoantibodies were strongly associated with renal diseases and can be used for the prediction of patients with lupus nephritis (LN). However, antibodies to dsDNA and the reduction of complements were also detected in non-LN patients as well as clinically non-active SLE patients. The current study was performed to detect the role of serum DKK-1 as a biomarker for the identification of SLE patients and patients with LN and its relation to disease activity and severity. The study was conducted on fifty clinically diagnosed SLE patients who were diagnosed according to Systemic Lupus International Collaborating Clinics (SLICC) classification criteria for SLE, in addition to thirty healthy control volunteers matched for age and sex. Assessment of SLE disease activity was done using Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Assessment of SLE disease severity was done using the Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) damage index. Serum levels of DKK-1 were measured for all participants by ELISA using commercially available kits. DKK-1 serum levels were significantly higher among active lupus nephritis cases as compared with SLE cases with no LN and with healthy controls (9197.60 μg/uL ± 2939.2 μg/uL vs. 6405.15 μg/uL ± 2018.91 μg/uL vs. 2790.33 μg/uL ± 833.49 μg/uL) respectively (p-values <\u20090.001). DKK-1 concentration was significantly higher among SLE patients with positive as compared with negative anti-double-stranded DNA (dsDNA) antibodies (p-value <\u20090.001). According to receiver operating characteristic (ROC) curve analysis, serum DKK-1 level diagnosed the SLE at a statistically significant level with a 98% sensitivity and 70% specificity and serum DKK-1 level also diagnosed active lupus nephritis at a 90% sensitivity and 63% specificity. DKK-1 could diagnose SLE and lupus nephritis with high sensitivity and specificity. Serum DKK-1 is a reliable biomarker for the identification of SLE and patients with LN and could be used as a key molecule for the diagnosis of SLE and as a prognostic indicator of LN.