Relation between Vitamin D Level and Cyclin-Dependent Kinase-1 Gene Expression in Egyptian Patients with Lupus Nephritis and their Impact on Disease Activity

INTRODUCTION: Lupus nephritis (LN) is a common complication of systemic lupus erythematosus. Vitamin D and cycline-dependent kinase-1 (CDK1) have been implicated in its pathogenesis. The aim of this study was to determine the relation between vitamin D level and CDK-1 in lupus nephritis patients and their impact on disease activity. PATIENTS AND METHODS: The current study was conducted on 50 LN patients and 20 control subjects from Egyptian population using ELISA to assess vitamin D level in serum and TaqMan assay for CDK1 gene expression. RESULTS: Serum vitamin D level was significantly lower in LN patients and CDK-1 gene was down expressed in the majority of LN patients. A significant inverse correlation was found between vitamin D level and 24 h protein in urine, ANA, anti-dsDNA, CRP, with a significant positive correlation with renal biopsy indices, eGFR. There was a non-significant inverse correlation between vitamin D and CDK-1 (before RO-3306 addition) and a positive correlation after RO-3306. A significant positive correlation was found between CDK-1 gene expressions with urinary albumin/creatinine ratio. However, a significant positive correlation was found between CDK-1 (after RO-3306 addition) and proteinuria. While a significant positive correlation was found between CDK-1 expression (after RO-3306 addition) and ANA, a significant positive correlation was found between CDK-1 expression (before RO-3306 addition) and anti-dsDNA but CDK-1 is not associated with renal biopsy indices nor with activity indices of SLE. There was a positive correlation between CDK-1 gene expression and CRP before and after RO-3306 addition. CONCLUSIONS: Vitamin D deficiency acts as a risk factor for developing LN. CDK-1 may have an association with the diagnosis of LN but its association with the progression of staging of LN is still confusing