title: Localization of vascular adhesion protein-1 (VAP-1) in the human eye.
abstract: 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 microg/ml), smooth muscle actin (1 microg/ml), CD31 or isotype-matched IgG at 4 degrees 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.
authors.affiliation: Angiogenesis Laboratory, Massachusetts Eye & Ear Infirmary, Harvard Medical School, 325 Cambridge Street, 3rd Floor, Boston, MA 02114, USA.
authors.forename: Lama
authors.initials: L
authors.lastname: Almulki
authors.forename: Kousuke
authors.initials: K
authors.lastname: Noda
authors.forename: Shintaro
authors.initials: S
authors.lastname: Nakao
authors.forename: Toshio
authors.initials: T
authors.lastname: Hisatomi
authors.forename: Kennard L
authors.initials: KL
authors.lastname: Thomas
authors.forename: Ali
authors.initials: A
authors.lastname: Hafezi-Moghadam
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D001158:Arteries / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002829:Choroid / Q000098:blood supply / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D005123:Eye / Q000098:blood supply* / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007124:Immunoenzyme Techniques; D007498:Iris / Q000098:blood supply / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000098:blood supply / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D012171:Retinal Vessels / Q000378:metabolism; D012590:Sclera / Q000098:blood supply / Q000378:metabolism; D014680:Veins / Q000378:metabolism
chemical_list: D000199:Actins; D015815:Cell Adhesion Molecules; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C076668:AOC3 protein, human; D006631:Amine Oxidase (Copper-Containing)