Reduction of experimental diabetic vascular leakage and pericyte apoptosis in mice by delivery of αA-crystallin with a recombinant adenovirus

Abstract

Aims/hypothesis The study aimed to evaluate the efficacy of recombinant adenovirus expressing αA-crystallin (Ad-αAc-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes. Methods Diabetes was induced by streptozotocin injection into C57BL/6 mice. Ad-αAc-Gfp was delivered by intravitreous injection to the right eyes of mice 2 weeks before induction of diabetes. Vascular leakage was determined by fluorescent angiography, Evans Blue leakage assay and leucocyte adhesion test. Production of αA-crystallin was analysed by immunoblotting and double immunostaining and pericyte loss was analysed by pericyte count. Results Vessel leakage and pericyte loss were observed in the streptozotocin-induced diabetic retina. Decreased abundance of αA-crystallin in retinas 2 and 6 months after the induction of diabetes was confirmed by two-dimensional electrophoretic analysis, immunoblotting and RT-PCR. Double immunofluorescence staining for αA-crystallin and NG2 chondroitin sulphate proteoglycan revealed that αA-crystallin was predominantly produced in the retinal pericyte and that the number of αA-crystallin-producing pericytes decreased in the diabetic retina. Retinal infection with Ad-αAc-Gfp led to decreased pericyte loss and vascular leakage compared with control. Conclusions/interpretation Intravitreal delivery of Ad-αAc-Gfp protects against vascular leakage in the streptozotocininduced model of diabetes. This effect is associated with the inhibition of diabetic retinal pericyte loss in early diabetes, suggesting that αA-crystallin has a role in preventing the pathogenesis of early diabetic retinopathy.

Chaperone Peptides of α-Crystallin Inhibit Epithelial Cell Apoptosis, Protein Insolubilization, and Opacification in Experimental Cataracts

“…If the peptides can cross the blood retinal barrier, they may be useful for inhibiting apoptosis in such diseases. In fact, ␣-crystallin delivery has been shown to reduce pericyte loss in an experimental diabetes model (40). In addition, it has been shown that ␣A-crystallin is protective against experimentally induced autoimmune uveitis (41) and ischemic optic neuropathy (42).…”

Alpha crystallins in the retinal pigment epithelium and implications for the pathogenesis and treatment of age-related macular degeneration

“…It is of interest that in EAE, the anti-inflammatory property of αB crystallin was not found to be due to influencing the adaptive immune response directly, but by binding and the subsequent modulation of the pro-inflammatory mediators in plasma [93]. In addition, intravitreal delivery of recombinant adenovirus expressing αA crystallin has been shown to protect against vascular leakage and effectively prevents pericyte loss and BRB breakdown in an experimental diabetes model [94]. Exogenous administration of αA crystallin attenuated corneal neovascularization in mouse models potentially by increasing the expression of soluble VEGFR1 [57].…”

Loss of the small heat shock protein αA-crystallin does not lead to detectable defects in early zebrafish lens development

“…Investigations into the extralenticular roles of αB-crystallin have identified changes in expression levels linked to multiple neurological disorders (Renkawek et al, 1999; Clark and Muchowski, 2000; Ousman et al, 2007) and cancer (Stegh et al, 2008), and a mutation in αB-crystallin that causes an inherited cardiac myopathy (Vicart et al, 1998). Recent studies have detailed a range of extralenticular roles for αA-crystallin as well, including the protection of retinal cells against diabetes (Kim et al, 2012) and autoimmune uveitis (Rao et al, 2008; 2012), and a potential role in retinoblastoma tumor growth (Kase et al, 2009). Alpha A-crystallin has also been shown to be an inhibitor of pancreatic carcinogenesis (Deng et al, 2010).…”