Alteration of Leukocyte–Endothelial Cell Interaction During Aging in Retinal Microcirculation of Hypertensive Rats

Abstract

Hypertension, one of the more common chronic diseases affecting the elderly, has been reported to influence leukocyte-endothelial cell interaction. The leukocyte-mediated inflammatory process contributes to age-related changes in vessels. This study was designed to evaluate age-related changes in leukocyte-endothelial cell interaction in the hypertensive rat retina. Male spontaneous hypertensive rats (SHR; 1.5, 3, 6, 12, and 20 months of age) and age-matched Wistar-Kyoto rats (WKY) were used. The number of accumulated leukocytes was counted in sections of flat-mounted retinal tissue. The expression of intercellular adhesion molecule-1 (ICAM-1) and CD18 (the common beta-chain of ICAM-1 ligands) was evaluated. Retinal thickness was evaluated histologically. The number of accumulated leukocytes and the expression of ICAM-1 and CD18 increased in the aged retina. The number of leukocytes that accumulated and the expression of CD 18 were significantly higher in the SHR group than in the WKY group (P < 0.01). In addition, retinal thickness decreased with age. Leukocyte-endothelial cell interaction increased in the aged retina and these changes were more severe in SHR retina than in WKY retina. This increased interaction was first observed at 3 months, a relatively young age.