Objective: To explore the effect of paraoxonase-1 (PON-1) and oxidized low density lipoprotein (ox-LDL) in diabetic nephropathy (DN).
Methods: Serum PON-1 activity was measured by using phenyl acetate as a substrate and the concentration of plasma ox-LDL was determined by ELISA in 91 cases of type 2 diabetes mellitus (DM). Simultaneously, serum NO, VWF and GMP 140 were also determined. The patients of DM were divided into three groups according to urine albumine excretion rate (UAER) (DM I: UAER < 30 mg/24 h; DM II: UAER 30 approximately 300 mg/24 h; DM III: UAER > 300 mg/24 h) and matched with normal controls (NC).
Results: In the three groups of DM, PON-1 were markedly decreased and ox-LDL were obviously increased (P < 0.01). Both of their levels were different in the three groups of DM (P < 0.05). PON-1 were negatively correlated with ox-LDL (r = -0.467, P < 0.01). There were negative correlation between PON-1 and urine albumin (r = -0.697, P < 0.01), but ox-LDL was positively correlated with urine albumin (r = 0.747, P < 0.01). Serum nitrites (NO) level in DM I was significantly higher than that in NC, but the NO level in DM II and DM III was lower than that in DM I and NC. GMP 140 and VWF levels in all the 3 DM groups were higher than that in NC. PON-1 was positively correlated with NO (r(s) = 0.326, P < 0.01), and negatively correlated with VWF (r(s) = -0.365, P < 0.01). ox-LDL was negatively correlated with NO (r(s) = -0.196, P < 0.05), but positively correlated with VWF and GMP 140 (r(s) = 0.294, P < 0.05; r(s) = 0.669, P < 0.01 respectively). Logistic regression showed that ox-LDL was a dangerous factor for DN.
Conclusion: PON-1, ox-LDL, NO, endothelial and platelet function are connected with DN; they affect one another and influence the occurrence and development of DN together.