Advanced glycation end product (AGE) modified proteins in tears of diabetic patients

[摘要] Purpose: High glucose level in diabeticpatients may lead to advanced glycation end product (AGE) modifiedproteins. This study investigated AGE modified proteins in tears andcompared their levels in diabetic patients (DM) with non-diabeticcontrols (CTL). Methods: Basal tears were collected fromDM with (DR) or without (DNR) retinopathy and CTL. Total AGE modifiedproteins were detected quantitatively by a dot immunobinding assay. TheAGE modified proteins were separated in 1D- and 2D-SDS gels anddetected by western-blotting. The individual AGE modified proteins werealso compared between groups using densitometry. Results: Compared with the CTL group,tear concentrations of AGE modified proteins were significantlyelevated in DR and DNR groups. The concentration of AGE modifiedproteins in diabetic tears were positively correlated with AGE modifiedhemoglobin (HbA1c) and postprandial blood glucose level (PBG). Westernblotting of AGE modified proteins from 1D-SDS gels showed severalbands, the major one at around 60 kDa. The intensities of AGEmodified protein bands were higher in DM tears than in CTL tears.Western blotting from 2D-SDS gels showed a strongly stained horizontalstrip, which corresponded to the major band in 1D-SDS gels. Most of theother AGE modified protein species were within molecular weight of30–60 kDa, PI 5.2–7.0. Densitometry analysis demonstrated severalAGE modified proteins were elevated in DR or DNR tears. Conclusions: Total and some individualAGE modified proteins were elevated in DM tears. AGE modified proteinsin tears may be used as biomarkers to diagnose diabetes and/or diabeticretinopathy.

[学科分类] 生物化学/生物物理