Localization of vascular adhesion protein-1 (VAP-1) in the human eye

Lama Almulki, Kousuke Noda, Shintaro Nakao, Toshio Hisatomi, Kennard L. Thomas, Ali Hafezi-Moghadam

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25 Citations (Scopus)


Recently we showed a critical role for Vascular Adhesion Protein-1 (VAP-1) in rodents during acute ocular inflammation, angiogenesis, and diabetic retinal leukostasis. However, the expression of VAP-1 in the human eye is unknown. VAP-1 localization was therefore investigated by immunohistochemistry. Five micrometer thick sections were generated from human ocular tissues embedded in paraffin. Sections were incubated overnight with primary mAbs against VAP-1 (5 μg/ml), smooth muscle actin (1 μg/ml), CD31 or isotype-matched IgG at 4 °C. Subsequently, a secondary mAb was used for 30 min at room temperature, followed by Dako Envision + HRP (AEC) System for signal detection. The stained sections were examined using light microscopy and the signal intensity was quantified by two evaluators and graded into 4 discrete categories. In all examined ocular tissues, VAP-1 staining was confined to the vasculature. VAP-1 labeling showed the highest intensity in both arteries and veins of neuronal tissues: retina and optic nerve, and the lowest intensity in the iris vasculature (p < 0.05). Scleral and choroidal vessels showed moderate staining for VAP-1. VAP-1 intensity was significantly higher in the arteries compared to veins (p < 0.05). Furthermore, VAP-1 staining in arteries colocalized with both CD31 and smooth muscle actin (sm-actin) staining, suggesting expression of VAP-1 in endothelial cells, smooth muscle cells or potentially pericytes. In conclusion, immunohistochemistry reveals constitutive expression of VAP-1 in human ocular tissues. VAP-1 expression is nearly exclusive to the vasculature with arteries showing significantly higher expression than veins. Furthermore, VAP-1 expression in the ocular vasculature is heterogeneous, with the vessels of the optic nerve and the retina showing highest expressions. These results characterize VAP-1 expression in human ocular tissues.

Original languageEnglish
Pages (from-to)26-32
Number of pages7
JournalExperimental Eye Research
Issue number1
Publication statusPublished - Jan 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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