Homocysteinethiolactone and paraoxonase: novel markers of diabetic retinopathy.
Homocysteinethiolactone and paraoxonase: novel markers of diabetic retinopathy.
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DOI：
10.2337/dc10-0132
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发表时间：
2010-09
期刊：
影响因子：
16.2
通讯作者：
Sivashanmugham M
中科院分区：
文献类型：
--
作者：
Barathi S;Angayarkanni N;Pasupathi A;Natarajan SK;Pukraj R;Dhupper M;Velpandian T;Muralidharan C;Sivashanmugham M
对氧磷酶（PON）具有酯酶活性（PON- arease）和内酯酶活性（PON- hctlase），可防止LDL氧化和解毒同型半胱氨酸硫内酯（HCTL）。HCTL和pon -HCTL酶在玻璃体水平上作为糖尿病视网膜病变微血管并发症的危险因素的作用尚未研究。采用增生性糖尿病视网膜病变（PDR）患者（n = 13）和黄斑孔（MH）患者（n = 8）未稀释玻璃体分光光度法测定pon - hcttlase和pon - area ase活性。采用液相色谱-串联质谱法检测HCTL水平。在原代培养的牛视网膜毛细血管内皮细胞（BRECs）中进行了体外研究，以确定HCTL和同型半胱氨酸（Hcys）对PON- hcttlase活性的剂量依赖性和时间依赖性，并通过RT-PCR检测PON mRNA的表达。PDR患者HCTL和pon -HCTL酶活性显著高于MH患者（P = 0.036, P = 0.001），二者呈正相关（r = 0.77, P = 0.03）。BRECs的体外研究显示，暴露于HCTL和Hcys时，pon - hcttlase活性和PON2 mRNA表达呈剂量和时间依赖性增加。这是第一个显示PDR玻璃体HCTL和pon -HCTL酶活性升高的研究。这些升高可能是消除介导内皮细胞功能障碍的HCTL的保护作用。因此，玻璃体中HCTL和PON活性水平可以作为糖尿病视网膜病变的标志。生物信息学分析显示PDR高同型半胱氨酸血症可调节PON的结构和功能，从而影响PON的双酶活性。
Paraoxonase (PON) exhibits esterase activity (PON-AREase) and lactonase activity (PON-HCTLase), which prevent LDL oxidation and detoxify homocysteine thiolactone (HCTL). The role of HCTL and PON-HCTLase as a risk factor for the microvascular complication in diabetic retinopathy at the level of vitreous has not been investigated. Undiluted vitreous from patients with proliferative diabetic retinopathy (PDR) (n = 13) and macular hole (MH) (n = 8) was used to determine PON-HCTLase and PON-AREase activity spectrophotometrically. HCTL levels were detected by liquid chromatography–tandem mass spectrometry. In vitro studies were done in primary cultures of bovine retinal capillary endothelial cells (BRECs) to determine the dose- and time-dependent effect of HCTL and homocysteine (Hcys) on PON-HCTLase activity, as well as to determine mRNA expression of PON by RT-PCR. A significant increase in HCTL and PON-HCTLase activity was observed in PDR compared with MH (P = 0.036, P = 0.001), with a significant positive correlation between them (r = 0.77, P = 0.03). The in vitro studies on BRECs showed a dose- and time-dependent increase in the PON-HCTLase activity and mRNA expression of PON2 when exposed to HCTL and Hcys. This is the first study showing elevated levels of vitreous HCTL and PON-HCTLase activity in PDR. These elevations are probably a protective effect to eliminate HCTL, which mediates endothelial cell dysfunction. Thus, vitreous levels of HCTL and PON activity can be markers of diabetic retinopathy. The bioinformatics analysis reveals that the structure and function of PON that can be modulated by hyperhomocysteinemia in PDR can affect the dual-enzyme activity of PON.