M. Endo et al., Increased levels of vascular endothelial growth factor and advanced glycation end products in aqueous humor of patients with diabetic retinopathy, HORMONE MET, 33(5), 2001, pp. 317-322
Clinical studies have shown a relationship between diabetic retinopathy and
Vascular endothelial growth factor (VEGF) levels in ocular fluid. Advanced
glycation end products (AGEs) have been implicated in diabetes complicatio
ns, including diabetic retinopathy. N-epsilon-(carboxymethyl) lysine (CML)
is a glycoxidation product that may be a marker of oxidative stress. In thi
s study, we used enzyme-linked immunosorbent assays to determine the levels
of VEGF, non-CML AGE and CML in the aqueous humor and serum of 82 Japanese
patients with type 2 diabetes and 60 non-diabetic subjects. VEGF, non-CML
ACE, and CML concentrations in aqueous humor and serum were then compared w
ith the severity of diabetic retinopathy, Immunohistochemical detection ana
lysis of non-CML ACE and CML was also performed using retinal tissues from
patients with progressive diabetic retinopathy. Aqueous levels of VEGF, non
-CML ACE and CML increased along with the progression of diabetic retinopat
hy compared to age-matched controls. After coagulation therapy, the VEGF, n
on-CML AGE, and CML levels were significantly reduced. Immunostaining showe
d diffuse co-localization of non-CML ACE and CML around microvessels and in
the glial cells of proliferative membranes from patients with progressive
diabetic retinopathy. These findings suggest that glycation and glycoxidati
on reactions (or oxidation, as revealed by CML) may contribute to both the
onset and progression of diabetic retinopathy.