Paraoxonase 1 Activity and its Polymorphism in Type 2 Diabetic Nephropathy

ABSTRACT

Objective: This study aims to investigate the role of paraoxonase 1 activity and Q192R polymorphism in the development of nephropathy in patients with Type 2 diabetes mellitus.

Material and Methods: This case-control study included 100 patients with Type 2 diabetes mellitus for more than five years, admitted to our hospital. They were divided into two groups (with and without diabetic nephropathy) on the basis of albumin-creatinine ratio. Serum samples of all patients were subjected to paraoxonase 1 arylesterase activity, using phenylacetate as the substrate. Paraoxonase 1 phenotyping was carried out by calculating the ratio of inhibited arylesterase activity to non-inhibited arylesterase activity using phenylacetate and p-nitrophenyl acetate, respectively, as substrates.

Results: Paraoxonase 1 arylesterase activity was found to be significantly lower in subjects with diabetic nephropathy than that in the subjects without diabetic nephropathy (85.4±24.12 vs. 127.94±25.51 p=0.01). Bothunivariate (Odds ratio=1.073, Neglekerke’s R2=0.565, area under the curve=0.888, p≤0.001) and multivariate (Odds ratio= 1.067, [95% confidence interval (1.023-1.113), p=0.003)] logistic tests showed independent, protective association of paraoxonase 1 arylesterase activity with the development of diabetic nephropathy. Paraoxonase 1 RR homozygous diabetic patients were observed to be significantly associated with diabetic nephropathy in the univariate logistic regression (R2=0.056 area under the curve=0.600 p=0.037), while the multivariate analysis did not show any significance.

Conclusion: A decreased paraoxonase 1 arylesterase activity may be considered to be an additional risk factor in the development of nephropathy in diabetes mellitus. Paraoxonase 1 RR homozygous individuals may be at an increased risk of being affected by diabetic nephropathy.