Abstract
Retinitis Pigmentosa is a common form of hereditary retinal degeneration constituting the largest Mendelian genetic cause of blindness in the developed world. It has been widely suggested that oxidative stress possibly contributes to its pathogenesis. We measured the levels of total antioxidant capacity, free nitrotyrosine, thiobarbituric acid reactive substances (TBARS) formation, extracellular superoxide dismutase (SOD3) activity, protein, metabolites of the nitric oxide/cyclic GMP pathway, heme oxygenase-I and inducible nitric oxide synthase expression in aqueous humor or/and peripheral blood from fifty-six patients with retinitis pigmentosa and sixty subjects without systemic or ocular oxidative stress-related disease. Multivariate analysis of covariance revealed that retinitis pigmentosa alters ocular antioxidant defence machinery and the redox status in blood. Patients with retinitis pigmentosa present low total antioxidant capacity including reduced SOD3 activity and protein concentration in aqueous humor. Patients also show reduced SOD3 activity, increased TBARS formation and upregulation of the nitric oxide/cyclic GMP pathway in peripheral blood. Together these findings confirmed the hypothesis that patients with retinitis pigmentosa present reduced ocular antioxidant status. Moreover, these patients show changes in some oxidative-nitrosative markers in the peripheral blood. Further studies are needed to clarify the relationship between these peripheral markers and retinitis pigmentosa.
Highlights
Retinal degenerations are the major cause of incurable blindness characterized by loss of retinal photoreceptor cells
multivariate analysis of covariance (MANCOVA) was carried out considering all response variables (TAC, SOD3, thiobarbituric acid reactive substances (TBARS), cGMP and NOX) simultaneously (*p,0.05, **p,0.01). doi:10.1371/journal.pone.0074223.t004
We determined the levels of different markers of the antioxidantoxidant status in aqueous humor and blood from Retinitis Pigmentosa (RP) patients, and compared them with those in healthy controls to confirm an alteration of this status
Summary
Retinal degenerations are the major cause of incurable blindness characterized by loss of retinal photoreceptor cells. Retinitis Pigmentosa (RP) is a common form of retinal degeneration, constituting the largest Mendelian genetic cause of blindness in the developed world. It has a prevalence of 1 in 4000, and it has been estimated that about two million people are affected worldwide. Patients with RP typically loose night vision in adolescence, peripheral vision in young adulthood, and central vision later in life due to the progressive loss of rod and cone photoreceptor cells by apoptosis [1]. About 20% of patients have an associated hearing loss and the combination is called Usher syndrome. There are approximately 60 genes implicated in the pathology of RP [2,3]
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