Intracellular cytoskeleton and junction proteins of endothelial cells in the porcine iris microvasculature.
Recently we reported studies of the iris microvasculature and its endothelial cells using intra-luminal micro-perfusion, fixation, and silver staining, suggesting that the iris vascular endothelium may be crucial for maintaining homeostasis in the ocular anterior segment. Here we present information regarding the intracellular structure and cell junctions of the iris endothelium. Thirty-seven porcine eyes were used for this study. The temporal long posterior ciliary artery was cannulated to assess the iris microvascular network and its endothelium using intra-luminal micro-perfusion, fixation, and staining with phalloidin for intracellular cytoskeleton f-actin, and with antibodies against claudin-5 and VE-cadherin for junction proteins. Nuclei were counterstained with Hoechst. The iris was flat-mounted for confocal imaging. The iris microvasculature was studied for its distribution, branch orders and endothelial morphometrics with endothelial cell length measured for each vessel order. Our results showed that morphometrics of the iris microvasculature was comparable with our previous silver staining. Abundant stress fibres and peripheral border staining were seen within the endothelial cells in larger arteries. An obvious decrease in cytoplasmic stress fibres was evident further downstream in the smaller arterioles, and they tended to be absent from capillaries and veins. Endothelial intercellular junctions throughout the iris vasculature were VE-cadherin and claudin-5 immuno-positive, indicating the presence of both adherent junctions and tight junctions between vascular endothelial cells throughout the iris microvasculature. Unevenness of claudin-5 staining was noted along the endothelial cell borders in almost every order of vessels, especially in veins and small arterioles. Our results suggest that significant heterogeneity of intracellular structure and junction proteins is present in different orders of the iris vasculature in addition to vascular diameter and shape of the endothelia. Detailed information of the topography and intracellular structure and junction proteins of the endothelium of the iris microvasculature combined with unique structural features of the iris may help us to further understand the physiological and pathogenic roles of the iris vasculature in relevant ocular diseases.
Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia; Lions Eye Institute, The University of Western Australia, Perth, Australia; Department of Ophthalmology & Visual Science, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
Hongfang
H
Yang
Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia; Lions Eye Institute, The University of Western Australia, Perth, Australia.
Paula K
PK
Yu
Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia; Lions Eye Institute, The University of Western Australia, Perth, Australia.
Stephen J
SJ
Cringle
Department of Ophthalmology & Visual Science, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Key Laboratory of Myopia, Ministry of Health, Fudan University, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, China. Electronic address: xhsun@shmu.edu.cn.
Xinghuai
X
Sun
Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia; Lions Eye Institute, The University of Western Australia, Perth, Australia. Electronic address: dyyu@lei.org.au.
Dao-Yi
DY
Yu
D000199:Actins / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism*; D019842:Ciliary Arteries / Q000378:metabolism; D062507:Claudin-5 / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D007365:Intercellular Junctions / Q000378:metabolism*; D007498:Iris / Q000098:blood supply*; D018613:Microscopy, Confocal; D055806:Microvessels; D034421:Sus scrofa; D000099152:Cadherin 5
D000199:Actins; D015703:Antigens, CD; D015820:Cadherins; D062507:Claudin-5; D000099152:Cadherin 5
Claudin-5; Cytoskeleton; Endothelium; Iris microvasculature; Junction proteins; Micro-perfusion; VE-cadherin