Elevation of apolipoprotein A-I and apolipoprotein H levels in the vitreous fluid and overexpression in the retina of diabetic patients.

OBJECTIVES To determine levels of apolipoprotein (apo) A-I and apo H in the vitreous fluid of patients with proliferative diabetic retinopathy (PDR) and to examine whether apo A-I and apo H messenger RNA (mRNA) levels are overexpressed in the diabetic retina. METHODS Vitreous samples from 4 diabetic patients with PDR and 8 nondiabetic patients with macular hole were selected for proteomic analysis. Fourteen additional samples (7 from patients with PDR and 7 from patients with macular hole) were used for Western blot analysis. Fourteen postmortem eyes (7 from diabetic and 7 from nondiabetic donors) were used to perform quantitative real-time polymerase chain reaction analysis. RESULTS Intravitreous apo A-I and apo H levels were significantly higher in patients with PDR than in the control group. The apo A-I and apo H mRNA levels obtained from the retinas of diabetic donors were significantly higher than those obtained from nondiabetic donors. Retinal pigment epithelium was the main contributor to the differences. CONCLUSIONS Levels of apo A-I and apo H are elevated in the vitreous fluid of diabetic patients with PDR. In addition, we provide the first evidence, to our knowledge, that a higher expression of apo A-I and apo H mRNAs exists in the diabetic retina. CLINICAL RELEVANCE The results of this study may be relevant to new treatment strategies aimed toward reducing the development of diabetic retinopathy.