CD13/aminopeptidase N mRNA expression and enzyme activity in Systemic Lupus Erythematosus

Aims: To determine the significance of CD13/aminopeptidase N (APN) in systemic Lupus Erythromatus (SLE), we examined its catalytic activity and mRNA expression level in sera and peripheral whole blood cells of patients with SLE. Methods: In this study, 47 SLE patients and 44 age, sex matched healthy controls were included. The SLE disease activity index score and clinical finding including renal involvement and blood pressure were recorded. Catalytic activities of CD13/APN were measured in serum samples. In addition, CD13 mRNA level in peripheral whole blood cells was analyzed by quantitative real-time PCR. Results: A Significant higher aminopeptidase activity was observed in serum from patients with SLE than serum from controls. In addition, CD13/APN mRNA expression was 6.12 times higher in SLE patients than in healthy controls. However, CD13/APN mRNA level, or its activity in serum, did not correlate with the score determined according to SLE disease activity index. Additionally, there was not any significant correlation between the complication in organs, including, kidney, and CD13/APN gene expression level or CD13/APN enzyme activity. Conclusion: CD13/APN enzyme activity and mRNA expression level were higher in SLE patients regardless of their disease activity. More studies are needed to better clarify the role of CD13/APN in the pathogenesis of SLE.