Alterations of retinal vasculature in cystathionine-beta-synthase mutant mice, a model of hyperhomocysteinemia

Amany Tawfik, Mohamed Al-Shabrawey, Penny Roon, Srinivas Sonne, Jason A. Covar, Surapoon Matragoon, Preethi S. Ganapathy, Sally S. Atherton, Azza El-Remessy, Vadivel Ganapathy, Sylvia B. Smith

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Purpose. Mice with moderate/severe hyperhomocysteinemia due to deficiency or absence of the cbs gene encoding cystathionine-beta-synthase (CBS) have marked retinal disruption, ganglion cell loss, optic nerve mitochondrial dysfunction, and ERG defects; those with mild hyperhomocysteinemia have delayed retinal morphological/functional phenotype. Excess homocysteine is a risk factor for cardiovascular diseases; however, it is not known whether excess homocysteine alters retinal vasculature. Methods. Cbs+/+, cbs+/-, and cbs-/- mice (age ~3 weeks) were subjected to angiography; retinas were harvested for cryosections, flat-mount preparations, or trypsin digestion and subjected to immunofluorescence microscopy to visualize vessels using isolectin-B4, to detect angiogenesis using anti-VEGF and anti-endoglin (anti-CD105) and activated glial cells (anti-glial fibrillary acidic protein [anti-GFAP]) and to investigate the blood-retinal barrier using the tight junction markers zonula occludens-1 (ZO-1) and occludin. Expression of vegf was determined by quantitative RT-PCR (qRT-PCR) and immunoblotting. Human retinal endothelial cells (HRECs) were treated with excess homocysteine to analyze permeability. Results. Angiography revealed vascular leakage in cbs-/- mice; immunohistochemical analysis demonstrated vascular patterns consistent with ischemia; isolectin-B4 labeling revealed a capillary-free zone centrally and new vessels with capillary tufts midperipherally. This was associated with increased vegf mRNA and protein, CD105, and GFAP in cbs-/- retinas concomitant with a marked decrease in ZO-1 and occludin. Homocysteine-treated HRECs showed increased permeability. Conclusions. Severe elevation of homocysteine in cbs-/- mutant mice is accompanied by alterations in retinal vasculature (ischemia, neovascularization, and incompetent blood-retinal barrier). The marked disruption of retinal structure and decreased visual function reported in cbs-/- mice may reflect vasculopathy as well as neuropathy.

Original languageEnglish (US)
Pages (from-to)939-949
Number of pages11
JournalInvestigative Ophthalmology and Visual Science
Volume54
Issue number2
DOIs
StatePublished - Feb 2013

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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