Abstract
Purpose: :
To messure concentrations of alpha-1-microglobulin (A1M), hemoglobin and oxidative stress in vitrectomy derived vitreous samples from patients with retinal detachment, diabetic retinopathy and macular hole, and to investigate the expression of A1M in the eye. Alpha-1-microglobulin (A1M) is a 26 kDa plasma and tissue protein that was discovered inhuman urine 40 years ago. A1M is synthesized predominantly in the liver, secreted to the blood stream and distributed to all tissues. Recent reports have shown that A1M has radical-scavenging and reductase properties and it is suggested that A1M functions as an antioxidant. A1M also binds and degrades heme. Expression of A1M is induced in the liver and blood cells when the cells are exposed to hemoglobin and it has also been shown that A1M protects human erythroid cells against the oxidative damage caused by free heme.
Methods: :
Measurement of human hemoglobin concentration in the vitreous body was performed using a competitive ELISA. Measurement of oxidative stress was performed using a carbonyl group ELISA.A radioimunoassay was used to measure the concentration of A1M. Real time PCR was performed to investigate the expression of A1M in rat retina explantats. A1M-forms in the vitreous body was analyzed by Western blotting.
Results: :
Hemoglobin, the oxidation product protein carbonyl groups and A1M were found in various amounts in the vitreous body. Novel forms of A1M, not previously seen in plasma, were found in the vitreous body. The A1M-gene is expressed in rat retina explants.
Conclusions: :
Analysis of vitrectomy derived vitreous samples from patients with retinal detachment, diabetic retinopathy and macular hole show that hemorrhage and oxidative stress may be common in patients with these pathological conditions. The results suggest that A1M plays a protective role against oxidative stress and cell injury caused by hemorrhage in the eye.
Keywords: antioxidants • stress response • protective mechanisms