[Significance of leukocytes in the regulation of retinal edema, ischemia, and angiogenesis].
BACKGROUND
Involvement of leukocytes in three major pathologic conditions in the retina, i.e., edema, ischemia, and angiogenesis, has recently been thoroughly investigated. The accumulated evidence will lead to an integrated understanding of the relationship between leukocytes and retinal disorders, which is required for clinical applications of new medical treatment.


METHODS
Leukocyte roles in the retinal vascular pathology were assessed by reviewing the related literature.


RESULTS
Vascular endothelial growth factor(VEGF)-induced leukocyte adhesion to the retinal vessels was shown to result in blood-retinal barrier breakdown, and the leukocyte-mediated pathogenesis was also seen in a model of diabetic retinopathy. A possible mechanism by which retinal angiogenesis develops intraviteral proliferation instead of compensating the avascular retina is that VEGF-producing monocytes/macrophages infiltrate the vitreous with subsequent migration of retinal vascular endothelial cells. On the other hand, cytotoxic T lymphocyte-mediated apoptosis of endothelial cells appears to cause the suppression of pathological retinal angiogenesis and the formation of ischemic retina secondary to vascular regression.


CONCLUSIONS
Leukocytes are considered to regulate retinal edema, ischemia, and angiogenesis.
Ishida
Susumu
S
Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
Yamashiro
Kenji
K
Usui
Tomohiko
T
Amano
Shiro
S
Ogura
Yuichiro
Y
Hida
Tetsuo
T
Oguchi
Yoshihisa
Y
D000818:Animals; D017209:Apoptosis; D002199:Capillary Permeability; D002448:Cell Adhesion; D002465:Cell Movement; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D007511:Ischemia / Q000209:etiology*; D007962:Leukocytes / Q000502:physiology*; D008264:Macrophages / Q000502:physiology; D009000:Monocytes / Q000502:physiology; D009389:Neovascularization, Pathologic / Q000209:etiology*; D010211:Papilledema / Q000209:etiology*; D012171:Retinal Vessels; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology; D014822:Vitreous Body / Q000166:cytology
D042461:Vascular Endothelial Growth Factor A