AAV-mediated gene therapy in Dystrophin-Dp71 deficient mouse leads to blood-retinal barrier restoration and oedema reabsorption

Abstract

Dystrophin-Dp71 being a key membrane cytoskeletal protein, expressed mainly in Müller cells that provide a mechanical link at the Müller cell membrane by direct binding to actin and a transmembrane protein complex. Its absence has been related to blood-retinal barrier (BRB) permeability through delocalization and down-regulation of the AQP4 and Kir4.1 channels (1). We have previously shown that the adeno-associated virus (AAV) variant, ShH10, transduces Müller cells in the Dp71-null mouse retina efficiently and specifically (2,3). Here, we use ShH10 to restore Dp71 expression in Müller cells of Dp71 deficient mouse to study molecular and functional effects of this restoration in an adult mouse displaying retinal permeability. We show that strong and specific expression of exogenous Dp71 in Müller cells leads to correct localization of Dp71 protein restoring all protein interactions in order to re-establish a proper functional BRB and retina homeostasis thus preventing retina from oedema. This study is the basis for the development of new therapeutic strategies in dealing with diseases with BRB breakdown and macular oedema such as diabetic retinopathy (DR).

Dysfunction of 67-kDa Laminin Receptor Disrupts BBB Integrity via Impaired Dystrophin/AQP4 Complex and p38 MAPK/VEGF Activation Following Status Epilepticus

“…Absence of dystrophin or deletion of base pairs in the dystrophin gene is a cause of Duchenne and Becker muscular dystrophy, which are allelic X-linked disorders with a progressive muscle weakness, a static cognitive impairment, autism and problems of behavior and attention (Young et al, 2008; de Brouwer et al, 2014). In mice models, deletion of dystrophin increases blood-retinal barrier (BRB) permeability by VEGF over-expression, and AQP4 delocalization/down-regulation (El Mathari et al, 2015; Vacca et al, 2016). In the brain, dystrophin deletion also reduces AQP4 expression over perivascular astroglial endfoot membranes (Enger et al, 2012).…”

The Regional Specific Alterations in BBB Permeability are Relevant to the Differential Responses of 67-kDa LR Expression in Endothelial Cells and Astrocytes Following Status Epilepticus

“…In addition, inhibition of AQP4 by acetazolamide (AZA) aggravates SE-induced vasogenic edema and astroglial loss in the PC, while it does not evoke vasogenic edema in control animals [3]. Deletion of dystrophin also reduces AQP4 expression over perivascular astroglial end foot membranes, which influences the degree of vasogenic edema formation [3,34,35,36,37,38]. In contrast to the PC, the hippocampus shows mild, not absent, changes in dystrophin-AQP4 expressions and serum-protein extravasations after SE [3].…”

Astrogliosis and impaired aquaporin‐4 and dystrophin systems in idiopathic normal pressure hydrocephalus

“…Inactivation of dystrophin and dystrophin gene products results in the brain and retina in, for example, abnormal blood circulation and water handling . The retina constitutes an integral part of the central nervous system and deletion of the dystrophin Dp71 gene induces in mice retinal vascular inflammation, degeneration and oedema . At human mesial temporal lobe epilepsy there is a loss of the DAPC including AQP4, associated with hippocampal degeneration and sclerosis .…”