Macular Degeneration: Miyahara S

Noda K, She H, Nakazawa T, Hisatomi T, Nakao S, Almulki L, Zandi S, Miyahara S, Ito Y, Thomas KL, Garland RC, Miller JW, Gragoudas ES, Mashima Y, Hafezi-Moghadam A. · Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA. · FASEB J. · Pubmed #18436961 links to  free full text

Abstract: Vascular adhesion protein-1 (VAP-1) is an endothelial cell adhesion molecule involved in leukocyte recruitment. Leukocytes and, in particular, macrophages play an important role in the development of choroidal neovascularization (CNV), an integral component of age-related macular degeneration (AMD). Previously, we showed a role for VAP-1 in ocular inflammation. Here, we investigate the expression of VAP-1 in the choroid and its role in CNV development. VAP-1 was expressed in the choroid, exclusively in the vessels, and colocalized in the vessels of the CNV lesions. VAP-1 blockade with a novel and specific inhibitor significantly decreased CNV size, fluorescent angiographic leakage, and the accumulation of macrophages in the CNV lesions. Furthermore, VAP-1 blockade significantly reduced the expression of inflammation-associated molecules such as tumor necrosis factor (TNF) -alpha, monocyte chemoattractant protein (MCP) -1, and intercellular adhesion molecule (ICAM) -1. This work provides evidence for an important role of VAP-1 in the recruitment of macrophages to CNV lesions, establishing a novel link between VAP-1 and angiogenesis. Inhibition of VAP-1 may become a new therapeutic strategy in the treatment of AMD.

Noda K, Miyahara S, Nakazawa T, Almulki L, Nakao S, Hisatomi T, She H, Thomas KL, Garland RC, Miller JW, Gragoudas ES, Kawai Y, Mashima Y, Hafezi-Moghadam A. · Department of Ophthalmology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts, USA. · FASEB J. · Pubmed #18032635 links to  free full text

Abstract: Inflammatory leukocyte accumulation is a common feature of major ocular diseases, such as uveitis, diabetic retinopathy, and age-related macular degeneration. Vascular adhesion protein-1 (VAP-1), a cell surface and soluble molecule that possesses semicarbazide-sensitive amine oxidase (SSAO) activity, is involved in leukocyte recruitment. However, the expression of VAP-1 in the eye and its contribution to ocular inflammation are unknown. Here, we investigated the role of VAP-1 in an established model of ocular inflammation, the endotoxin-induced uveitis (EIU), using a novel and specific inhibitor. Our inhibitor has a half-maximal inhibitory concentration (IC(50)) of 0.007 microM against human and 0.008 microM against rat SSAO, while its IC(50) against the functionally related monoamine oxidase (MAO) -A and MAO-B is >10 microM. In the retina, VAP-1 was exclusively expressed in the vasculature, and its expression level was elevated during EIU. VAP-1 inhibition in EIU animals significantly suppressed leukocyte recruitment to the anterior chamber, vitreous, and retina, as well as retinal endothelial P-selectin expression. Our data suggest an important role for VAP-1 in the recruitment of leukocytes to the immune-privileged ocular tissues during acute inflammation. VAP-1 inhibition may become a novel strategy in the treatment of ocular inflammatory diseases.

Musashi K, Kiryu J, Miyamoto K, Miyahara S, Katsuta H, Tamura H, Hirose F, Yoshimura N. · Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan. · Invest Ophthalmol Vis Sci. · Pubmed #15980248 links to  free full text

Abstract: PURPOSE: Macular edema is one of the most serious adverse effects after retinal scatter laser photocoagulation. It has been suggested that the inflammatory reaction after photocoagulation may be involved in the pathogenesis of macular edema. This study was designed to evaluate quantitatively the inhibitory effects of argatroban, a direct thrombin inhibitor, on leukocyte-endothelial cell interactions and vascular permeability after scatter laser photocoagulation. METHODS: Argon laser photocoagulation was performed in one half of the retina in pigmented male rats (n = 114). Argatroban was administered just before scatter laser photocoagulation. In the other half of the retina, AO leukocyte fluorography was used to evaluate in vivo leukocyte rolling along the retinal vein and accumulation in the retinal capillary bed. The expressions of P-selectin and intercellular adhesion molecule (ICAM)-1 were evaluated by reverse transcription-polymerase chain reaction. Retinal vessel permeability was quantified by using fluorescein isothiocyanate (FITC)-conjugated dextran. RESULTS: Scatter laser photocoagulation caused significant inflammatory leukocyte-endothelial cell interactions in the nonphotocoagulated half of the retina. Treatment with argatroban suppressed leukocyte-endothelial cell interactions. The maximum number of rolling and accumulating leukocytes was reduced by 46.6% (P < 0.01) and 51.4% (P < 0.01), respectively. The expression of P-selectin and ICAM-1 mRNA was suppressed significantly in the argatroban-treated retinas (P < 0.05). Retinal vascular permeability was also suppressed significantly (P < 0.05). CONCLUSIONS: Argatroban suppressed leukocyte-endothelial cell interactions and blood-retinal barrier breakdown after scatter laser photocoagulation, suggesting that argatroban prevents postlaser macular edema.

Tamura H, Miyamoto K, Kiryu J, Miyahara S, Katsuta H, Hirose F, Musashi K, Yoshimura N. · Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan. · Invest Ophthalmol Vis Sci. · Pubmed #15790913 links to  free full text

Abstract: PURPOSE: Recently, intravitreal injection of corticosteroids has been in wide use as a treatment for diabetic macular edema, and the outcomes have been favorable. However, the exact mechanism remains unclear. The hypothesis for the current study was that intravitreal corticosteroids may improve diabetic retinal edema by amelioration of blood-retinal barrier (BRB) breakdown, by inhibiting leukocyte stasis (leukostasis). METHODS: Diabetes was induced in 6-week-old male Long-Evans rats by intraperitoneal injection of streptozotocin (75 mg/kg). Three weeks after induction of diabetes, intravitreal injection of dexamethasone (40 microg/10 microL) was performed. At 2 days after intravitreal injection, accumulated leukocytes were counted in vivo by acridine orange leukocyte fluorography, and BRB breakdown was evaluated by measurement of retinal vascular permeability. The mRNA expression and protein levels of intercellular adhesion molecule (ICAM)-1 in the retina were also studied. RESULTS: The number of leukocytes accumulated in the retina, once increased in the diabetic group, was decreased by 31.6% (P = 0.0001) after dexamethasone injection. The level of BRB breakdown, also elevated in the diabetic group, was suppressed by 61.1% (P = 0.0046) after dexamethasone injection. The level of ICAM-1 mRNA expression and its protein, upregulated in the diabetic group, were downregulated by dexamethasone treatment by 70.0% (P < 0.0001) and 56.4% (P = 0.0003). CONCLUSIONS: Intravitreal injection of corticosteroids improves diabetic retinal edema through inhibiting leukocyte recruitment in the diabetic retina.

Kiryu J, Kita M, Tanabe T, Yamashiro K, Ieki Y, Miura S, Miyahara S, Tamura H, Honda Y. · Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan. · Jpn J Ophthalmol. · Pubmed #12967864 No free full text.

Abstract: PURPOSE: To examine retrospectively the visual outcomes in patients undergoing vitrectomy for epiretinal membranes secondary to sarcoid uveitis. METHODS: Eleven consecutive patients (11 eyes) with epiretinal membrane and uveitis associated with sarcoidosis underwent pars plana vitrectomy. RESULTS: Nine eyes (82%) gained two or more lines of Snellen visual acuity at 1-12 months after surgery. However, 4 of these 9 eyes lost two or more lines of Snellen visual acuity by the final visit. Overall, 5 eyes (45%) had attained at least two Snellen lines of visual acuity improvement, 5 eyes (45%) were unchanged, and 1 eye (10%) had worsened by two lines at the final visit. Nine eyes (81%) achieved visual acuity of 20/40 or better by the final visit. Slit-lamp biomicroscopy and fluorescein angiography showed that cystoid macular edema had resolved in 4 of 7 eyes postoperatively; vitritis improved in all cases. Postoperative complications included cataract formation, glaucoma, and membrane recurrence. Subsequent surgeries consisted of cataract extraction in 2 eyes and membrane peeling in 1 eye. CONCLUSIONS: Pars plana vitrectomy appears to have a beneficial effect on restoring vision in eyes with epiretinal membrane and uveitis associated with sarcoidosis, but final visual acuity was limited by the development of cataract and membrane recurrence.