Yuji Oshima

Genome-wide association study identifies two susceptibility loci for exudative age-related macular degeneration in the Japanese population

Age-related macular degeneration (AMD), the leading cause of irreversible blindness in the world, is a complex disease caused by multiple environmental and genetic risk factors. To identify genetic factors that modify the risk of exudative AMD in the Japanese population, we conducted a genome-wide association study and a replication study using a total of 1,536 individuals with exudative AMD and 18,894 controls. In addition to CFH (rs800292, P = 4.23 × 10−15) and ARMS2 (rs3750847, P = 8.67 × 10−29) loci, we identified two new susceptibility loci for exudative AMD: TNFRSF10A-LOC389641 on chromosome 8p21 (rs13278062, combined P = 1.03 × 10−12, odds ratio = 0.73) and REST-C4orf14-POLR2B-IGFBP7 on chromosome 4q12 (rs1713985, combined P = 2.34 × 10−8, odds ratio = 1.30). Fine mapping revealed that rs13278062, which is known to alter TNFRSF10A transcriptional activity, had the most significant association in 8p21 region. Our results provide new insights into the pathophysiology of exudative AMD.

IL-23–Independent Induction of IL-17 from γδT Cells and Innate Lymphoid Cells Promotes Experimental Intraocular Neovascularization

Choroidal neovascularization (CNV) is a characteristic of age-related macular degeneration. Genome-wide association studies have provided evidence that the immune system is involved in the pathogenesis of age-related macular degeneration; however, the role of inflammatory cytokines in CNV has not been established. In this study, we demonstrated that IL-17 had a strong potential for promoting neovascularization in a vascular endothelial growth factor–independent manner in laser-induced experimental CNV in mice. Infiltrated γδT cells and Thy-1+ innate lymphoid cells, but not Th17 cells, were the main sources of IL-17 in injured eyes. IL-23 was dispensable for IL-17 induction in the eye. Instead, we found that IL-1β and high-mobility group box 1 strongly promoted IL-17 expression by γδT cells. Suppression of IL-1β and high-mobility group box 1, as well as depletion of γδT cells, reduced IL-17 levels and ameliorated experimental CNV. Our findings suggest the existence of a novel inflammatory cytokine network that promotes neovascularization in the eye.

Periostin promotes the generation of fibrous membranes in proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is a severe, vision‐threatening disorder characterized by the fibrous membrane formation that leads to trac‐tional retinal detachment. There has been no effective therapeutic approach other than vitreoretinal surgery. In this study, DNA microarray analysis of the fibrous membranes revealed significant up‐regulation of periostin. We also found increased periostin expression in the vitreous and retinal pigment epithelial (RPE) cells from fibrous membranes of PVR patients. In vitro, periostin increased proliferation, adhesion, migration, and collagen production in RPE cells through integrin αVmediated FAK and AKT phosphorylation. Periostin blockade suppressed migration and adhesion induced by TGFβ2 and PVR vitreous. In vivo, periostin inhibition had the inhibitory effect on progression of experimental PVR in rabbit eyes without affecting the viability of retinal cells. These results identified periostin as a pivotal molecule for fibrous membrane formation as well as a promising therapeutic target for PVR.—Ishikawa, K., Yoshida, S., Nakao, S., Nakama, T., Kita, T., Asato, R., Sassa, Y., Arita, R., Miyazaki, M., Enaida, H., Oshima, Y., Murakami, N., Niiro, H., Ono, J., Matsuda, A., Goto, Y., Akashi, K., Izuhara, K., Kudo, A., Kono, T., Hafezi‐Moghadam, A., Ishibashi, T. Periostin promotes the generation of fibrous membranes in proliferative vitreoretinopathy. FASEB J. 28, 131–142 (2014). www.fasebj.org

Establishment of a new animal model of focal subretinal fibrosis that resembles disciform lesion in advanced age-related macular degeneration.

PURPOSEnSubretinal fibrosis causes damage to visual acuity, especially if the lesion is in the macula, as is frequently observed in advanced age-related macular degeneration. Exudate leukocytes form abnormal vessels that initiate regional inflammation accompanied with local glial proliferation and matrix production. The purpose of this study was to establish an animal model of focal subretinal fibrosis.nnnMETHODSnMacrophage-rich peritoneal exudate cells (PECs) were injected into the subretinal space of C57BL/6 or MCP-1 knockout (KO) mice. Seven days later, the size of the subretinal fibrotic tissue was evaluated by the adherent area of glial fibrillary acidic protein (GFAP)-positive retinal glial cells on choroidal flat mounts. Myofibroblastic changes and collagen synthesis were detected by α-smooth muscle actin (α-SMA) and Masson trichrome staining of the histologic section, respectively. α-SMA expression was also examined on retinal pigment epithelium (RPE) cells during co-culture with activated macrophages.nnnRESULTSnSubretinal fibrous tissue was observed by funduscopy in PEC-injected mice after 7 days. The tissue consisted of a monotonous, low-cell-density area that expressed α-SMA with collagen synthesis. Both steroid and antioxidant treatment can reduce residual glia. Because PEC-injected MCP-1 KO mice showed less residual glia, not only exogenous macrophages, but also intrinsic macrophages were activated. The macrophages directly induced myofibrotic changes in RPE cells in vitro.nnnCONCLUSIONSnActivated macrophages form subretinal fibrosis when they are placed in the subretinal space and induce myofibrotic changes in RPE cells.

Antiangiogenic shift in vitreous after vitrectomy in patients with proliferative diabetic retinopathy

PURPOSEnWe determined whether the concentrations of VEGF, erythropoietin, and endostatin in the vitreous are altered after vitrectomy in patient with proliferative diabetic retinopathy (PDR).nnnMETHODSnWe measured the levels of VEGF, erythropoietin, and endostatin by sandwich ELISA in vitreous samples collected from 38 eyes of 33 patients with PDR before pars plana vitrectomy (without IOL implantation) and the same 38 eyes during IOL implantation 3.1 to 25.7 (mean 6.7) months after the initial vitrectomy.nnnRESULTSnThe mean vitreous levels of VEGF (964.5 pg/mL) and erythropoietin (1359.5 pg/mL) in the samples collected before vitrectomy were significantly higher in patients with PDR than in the control patients (0.68 and 70.7 pg/mL, respectively; P < 0.01). The levels of VEGF (292.5 pg/mL) and erythropoietin (557.9 pg/mL) in the samples from eyes with PDR collected at the time of IOL implantation were significantly lower than those collected before vitrectomy (P < 0.01). In contrast, the changes in the level of endostatin were not significant after vitrectomy. The VEGF and erythropoietin levels in the vitreous fluid from patients with PDR were correlated inversely with the interval between the initial vitrectomy and the time of the IOL implantation.nnnCONCLUSIONSnThe significant decrease in the intravitreal concentration of VEGF and erythropoietin, and an absence of a significant change in the endostatin indicated a shift in the antiangiogenic balance in the vitreous of patients with PDR after successful vitrectomy.

A Novel Platelet-Activating Factor Receptor Antagonist Inhibits Choroidal Neovascularization and Subretinal Fibrosis.

Choroidal neovascularization (CNV) is a critical pathogenesis in age-related macular degeneration (AMD), the most common cause of blindness in developed countries. To date, the precise molecular and cellular mechanisms underlying CNV have not been elucidated. Platelet-activating factor (PAF) has been previously implicated in angiogenesis; however, the roles of PAF and its receptor (PAF-R) in CNV have not been addressed. The present study reveals several important findings concerning the relationship of the PAF-R signaling with CNV. PAF-R was detected in a mouse model of laser-induced CNV and was upregulated during CNV development. Experimental CNV was suppressed by administering WEB2086, a novel PAF-R antagonist. WEB2086-dependent suppression of CNV occurred via the inhibition of macrophage infiltration and the expression of proangiogenic (vascular endothelial growth factor) and proinflammatory molecules (monocyte chemotactic protein-1 and IL-6) in the retinal pigment epithelium–choroid complex. Additionally, WEB2086-induced PAF-R blockage suppresses experimentally induced subretinal fibrosis, which resembles the fibrotic subretinal scarring observed in neovascular AMD. As optimal treatment modalities for neovascular AMD would target the multiple mechanisms of AMD-associated vision loss, including neovascularization, inflammation and fibrosis, our results suggest PAF-R as an attractive molecular target in the treatment of AMD.

IL-27 inhibits pathophysiological intraocular neovascularization due to laser burn

AMD is the most common disease leading to acquired blindness in developed countries. CNV is the foremost cause of AMD and is thought to be induced by regional inflammation as a result of age‐related conformational changes of the chorioretinal interface. Here, we show that IL‐27, a member of the IL‐6/IL‐12 cytokine family, has an angiostatic effect and regulates the development of laser‐induced experimental CNV in mice. In this model, IL‐27 expression increased in the damaged choroid and peaked at the 24 h‐time‐point. IL‐27 neutralization, induced by inoculating an antagonistic antibody into the vitreous cavity, enhanced VEGF production and the extent of CNV. By contrast, the administration of rIL‐27 reduced VEGF production and the extent of CNV. Mice deficient in the EBI3, which lack IL‐27, also showed more CNV than C57BL/6 mice, and this was reduced by IL‐27 supplementation. We additionally investigated the effect of IL‐27 on the function of macrophages, which play a critical role in CNV. IL‐27 did not affect macrophage migration but inhibited its VEGF production. IL‐27 therefore appears to regulate CNV and is a promising candidate target for treating sight‐threatening diseases caused by ocular neovascularization.