TNFRSF10A downregulation induces retinal pigment epithelium degeneration during the pathogenesis of age-related macular degeneration and central serous chorioretinopathy.

Age-related macular degeneration (AMD) and central serous chorioretinopathy (CSC) are common diseases that can cause vision loss in older and younger populations. These diseases share pathophysiological conditions derived from retinal pigment epithelium (RPE) dysfunction. Tumor necrosis factor receptor superfamily 10A (TNFRSF10A)-LOC389641 with the same lead single-nucleotide polymorphism (SNP) (rs13278062) is the only overlapped susceptibility locus found in both AMD and CSC through genome-wide association studies. This lead SNP has been reported to alter the transcriptional activity of TNFRSF10A. This study aimed to elucidate the function of TNFRSF10A in RPE degeneration using human primary RPE cells and Tnfrsf10 knockout (Tnfrsf10-/-) mice. TNFRSF10A was found to be localized in human RPE. In vitro assays revealed that a T allele of rs13278062, the risk allele for AMD and CSC, downregulated TNFRSF10A transcription in RPE, leading to decreased cell viability and increased apoptosis through protein kinase C-α (PKCA) downregulation. Treatment with phorbol 12-myristate 13-acetate, a PKC activator, rescued the cell viability. Morphological RPE abnormality was found in the retina of Tnfrsf10-/- mice. Our data suggest that downregulation of TNFRSF10A expression inactivates PKCA signaling and causes cellular vulnerability of the RPE, which may contribute to the pathogenesis of AMD and CSC.

The factors associated with retinal pigment epithelium tear development in the early phase after treatment initiation for age-related macular degeneration.

PURPOSE: This study aimed to evaluate the factors associated with retinal pigment epithelium (RPE) tear development in the early phase after anti-vascular endothelial growth factor (VEGF) drug initiation in eyes with neovascular age-related macular degeneration (nAMD) and retinal pigment epithelial detachment (PED). METHODS: Treatment-naive eyes with nAMD and PED for which anti-VEGF drug injections had been initiated and followed up for at least 3 months after the 1st anti-VEGF drug injection, were retrospectively investigated. Baseline characteristics of the PEDs, including type, height, and area, were evaluated using fundus photographs, fluorescein angiography, and optical coherence tomography images. The association between patient age, sex, medical history, PED characteristics, and the development of RPE tears within 3 months of starting anti-VEGF therapy was examined. RESULTS: This study included 244 eyes (230 patients; mean age 75.0 years, 159 males and 71 females). RPE tears occurred in 13 eyes (5.3%) within 3 months of the start of anti-VEGF therapy. Multivariate analysis showed an association of the development of RPE tears with PED height (every 100 µm, odds ratio [OR]: 1.50, 95% confidence interval [CI]: 1.07-2.12, p = 0.019), PED area (every 10 mm2, OR: 3.02, CI: 1.22-7.46, p = 0.016), and the presence of fibrovascular PED (OR: 59.22, CI: 4.12-850.59, p = 0.002). Eyes with cleft (the hypo-reflective space beneath the fibrovascular PED) were more likely to develop an RPE tear (p = 0.01, χ-square test). CONCLUSIONS: Fibrovascular PED, large PED area, high PED height, and the cleft finding are independent risk factors for the development of RPE tears early after the administration of anti-VEGF drugs.

Three-month outcomes of treatment with faricimab or aflibercept for neovascular age-related macular degeneration: a propensity score matching study in a Japanese population.

PURPOSE: This study aimed to compare the treatment outcomes of patients with neovascular age-related macular degeneration (nAMD) who initially received faricimab or aflibercept treatment using propensity score matching (PSM) to align patient backgrounds. METHODS: Patients with treatment-naïve nAMD who received either faricimab or aflibercept for three consecutive monthly injections as the loading phase were enrolled in this study. In the 1:1 PSM, sex, age, best-corrected visual acuity (BCVA), central macular thickness (CMT), central choroidal thickness (CCT), and AMD subtypes in the pre-treatment state were selected as covariates. We examined the BCVA, CMT, CCT, and remaining fluid at 1-, 2-, and 3-month after the first injection. RESULTS: After PSM, 43 eyes were included in the faricimab and aflibercept group each. Both groups showed significant improvements in BCVA, CMT, and CCT at 1-, 2-, and 3-month after the initial injection compared with baseline. Meanwhile, no significant differences were observed between the two groups at any time point regarding BCVA, CMT, and CCT. At 1-month, 18.6% of patients in the faricimab group and 41.9% in the aflibercept group demonstrated residual subretinal fluid or intraretinal fluid, with a significant difference between the groups (P = 0.03). CONCLUSION: The BCVA improved after three loading injections of both faricimab and aflibercept. Faricimab may provide a favorable early treatment response in reducing subretinal fluid in a Japanese cohort.

Animal model of subretinal fibrosis without active choroidal neovascularization.

Subretinal fibrosis can occur during neovascular age-related macular degeneration (nAMD) and consequently provokes progressing deterioration of AMD patient's vision. Intravitreal anti-vascular endothelial growth factor (VEGF) injections decrease choroidal neovascularization (CNV), however, subretinal fibrosis remains principally unaffected. So far, no successful treatment nor established animal model for subretinal fibrosis exists. In order to investigate the impact of anti-fibrotic compounds on solely fibrosis, we refined a time-dependent animal model of subretinal fibrosis without active choroidal neovascularization (CNV). To induce CNV-related fibrosis, wild-type (WT) mice underwent laser photocoagulation of the retina with rupture of Bruch's membrane. The lesions volume was assessed with optical coherence tomography (OCT). CNV (Isolectin B4) and fibrosis (type 1 collagen) were separately quantified with confocal microscopy of choroidal whole-mounts at every time point post laser induction (day 7-49). In addition, OCT, autofluorescence and fluorescence angiography were carried out at designated timepoints (day 7, 14, 21, 28, 35, 42, 49) to monitor CNV and fibrosis transformation over time. From 21 to 49 days post laser lesion leakage in the fluorescence angiography decreased. Correspondingly, Isolectin B4 decreased in lesions of choroidal flat mounts and type 1 collagen increased. Fibrosis markers, namely vimentin, fibronectin, alpha-smooth muscle actin (α-SMA) and type 1 collagen were detected at different timepoints of tissue repair in choroids and retinas post laser. These results prove that the late phase of the CNV-related fibrosis model enables screening of anti-fibrotic compounds to accelerate the therapeutic advancement for the prevention, reduction, or inhibition of subretinal fibrosis.

Development of in situ crosslinked hyaluronan as an adjunct to vitrectomy surgery.

Ophthalmologists have used hyaluronan (HA) products as adjuncts to ocular surgery since the 1970s. However, HA products are not always functional in surgeries of the posterior eye segment due to their lack of biomechanical strength. In this study, we developed an in situ crosslinked HA (XL-HA) and evaluated its potential as an adjunct to vitrectomy surgery in an in vitro model with a triamcinolone acetonide (TA) layer used as a pseudo residual vitreous cortex (RVC). Within a few minutes at concentrations over 0.9%, XL-HA, generated by the click chemistry of HA-dibenzocyclooctyne and HA-azidoethylamine, formed a hydrogel with the appropriate hardness for tweezers peeling. XL-HA (concentration, 0.76-1.73%) without dispersion successfully entered the TA layer and removed more than 45% of the total TA. Dynamic viscoelasticity helps to explain the rheological behavior of hydrogels, and the assessment results for XL-HA indicated that suitable concentrations were between 0.97% and 1.30%. For example, 1.30% XL-HA hydrogel reached sufficient hardness at 3 min for tweezers peeling, and the TA removal ability exceeded 70%. These results demonstrated that XL-HA was a potential adjunct to successful vitrectomy.

Increased vitreous levels of B cell activation factor (BAFF) and soluble interleukin-6 receptor in patients with macular edema due to uveitis related to Behçet's disease and sarcoidosis.

PURPOSE: Uveitis accounts for 10-15% of all cases of blindness in the developed world. Uveitic macular edema (UME) is a primary cause of permanent visual impairment in patients with uveitis. Because proinflammatory mediators elicit inflammation and lead to UME, we determined the profiles of proinflammatory mediators associated with complications, such as ME, in the vitreous humor of patients with panuveitis related to Behçet's disease (BD) and sarcoidosis. METHODS: In this retrospective study, we enrolled 21 patients with uveitis, including 6 with BD and 15 with sarcoidosis, and 15 patients with idiopathic epiretinal membrane (iERM) at the Department of Ophthalmology, Kyushu University Hospital, between January 2008 and April 2016. Vitreous concentrations of 32 proinflammatory mediators, including cytokines and soluble receptors of tumor necrosis factor (TNF) and interleukin (IL)-6 families, were assessed using a bead-based multiplex assay and their association with clinical data was examined. RESULTS: The levels of proinflammatory mediators, including a proliferation-inducing ligand (APRIL), B cell activating factor belonging to the TNF family (BAFF), soluble cluster of differentiation 30 (sCD30), soluble TNF receptor-1 (sTNFR1), sTNFR2, TNF-α, IL-6, and soluble IL-6 receptor-α (sIL-6Rα), were significantly higher in patients with uveitis. With regard to clinical parameters in patients with uveitis, vitreous levels of BAFF and sIL-6Rα were prominently elevated in patients with UME compared to in those without UME (P < 0.01, respectively). CONCLUSIONS: Our results suggest that elevated vitreous levels of BAFF and sIL-6Rα are associated with the pathogenesis of UME in patients with panuveitis related to BD and sarcoidosis.

One-year efficacy of "rescue photodynamic therapy" for patients with typical age-related macular degeneration, polypoidal choroidal vasculopathy, and pachychoroid neovasculopathy refractory to anti-vascular endothelial growth factor therapy.

PURPOSE: This study aimed to evaluate the one-year outcomes of photodynamic therapy (PDT) as a rescue treatment for age-related macular degeneration (AMD) refractory to anti-vascular endothelial growth factor (VEGF) therapy. METHODS: Patients with AMD refractory to anti-VEGF therapy, treated with "rescue-PDT" were retrospectively investigated. The time of PDT was defined as the baseline value. Baseline characteristics including sex, age, best-corrected visual acuity (BCVA), central macular thickness (CMT), and foveal choroidal thickness (FCT) were examined. The changes in BCVA, CMT, and recurrence were also assessed at the 1-year follow-up. The logMAR VA change of 0.3 or more was defined as "improved" or "declined." RESULTS: Twenty-three consecutive eyes (typical AMD: 10 eyes, polypoidal choroidal vasculopathy: 10 eyes, and pachychoroid neovasculopathy: 3 eyes), which underwent "rescue-PDT," were analyzed in this study. The BCVA was improved in three patients and maintained in 20 patients at 12 months after PDT (mean BCVA change: 0.11 ± 0.19). The CMT improved in 19 patients (82.6%), and the mean CMT changed from 318.5 ± 93.7 µm to 225.9 ± 51.6 µm (p < 0.01) 12 months after PDT. "Retreatment" of anti-VEGF drug injections was considered if the retinal fluid or retinal hemorrhage recurred after PDT. The baseline FCT of the "retreatment group (15 eyes)" was significantly lower than that of the "no retreatment group (8 eyes)" (206.3 ± 50.7 µm vs 293.9 ± 85.7 µm: p = 0.033). CONCLUSIONS: PDT could be an effective treatment option for anti-VEGF refractory AMD to maintain visual acuity and control retinal fluid for up to 12 months.

Characteristics of retinal pigment epithelium elevations preceding exudative age-related macular degeneration in Japanese.

INTRODUCTION: Drusen and pigmentary abnormality are found as the hallmark to predict progression of age-related macular degeneration (AMD). In Asian populations, exudative AMD often appears in the absence of drusen but are rather accompanied by pigmentary abnormality. Recently, shallow irregular retinal-pigment-epithelium (RPE) elevations (SIRE) has been shown as a sign of subclinical non-exudative macular neovascularization. In this study, we aimed to investigate the characteristics of optical coherence tomography (OCT) findings including SIRE before the appearance of exudative AMD. METHODS: We retrospective reviewed 32 cases of exudative AMD that occurred in the fellow eye within the 5-years-observation period. Color fundus photography, OCT, and fluorescein/indocyanine green angiography at the beginning of observation and at the time when exudative AMD appeared were examined to diagnose SIRE and the subtype of exudative AMD. RESULTS: Exudative AMD were found in 19 eyes with large drusen and 13 eyes without large drusen. Mean sub-foveal choroidal thickness without large drusen were significantly thicker than those with large drusen (336 ± 109 and 220 ± 96 µm, respectively; mean± SD). Six eyes with pachychoroid neovasculopathy, 4 eyes with Type 1 macular neovascularization, and 3 eyes with PCV had occurred in the fellow eye without large drusen. Among those, 6 eyes had been accompanied by SIRE with a greatest transverse linear dimension of 1 mm or more at the beginning of observation-period. Besides, small RPE elevations with a longest diameter of less than 1 mm had been observed in other 5 eyes. Three cases of polypoidal choroidal vasculopathy had originated from small RPE elevations. Moreover, pachyvessels, choriocapillaris thinning, or choroidal hyperpermeability were observed with SIRE or small RPE elevation. CONCLUSIONS: There is a non-drusen type of exudative AMD that originates from small RPE elevations as well as SIRE.

Decrease in the number of microaneurysms in diabetic macular edema after anti-vascular endothelial growth factor therapy: implications for indocyanine green angiography-guided detection of refractory microaneurysms.

PURPOSE: We evaluated changes in the numbers of microaneurysms (MAs) on fluorescein angiography (FA) and indocyanine green angiography (IA) in eyes with diabetic macular edema (DME) following intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents. METHODS: Twenty-one eyes of 16 patients with DME were included in this retrospective study. All patients received an initial loading dose of three monthly injections of anti-VEGF agents; thereafter, they received a pro re nata regimen for at least 12 months of follow-up. FA and IA images were obtained before and at 6 months after the initial injection. RESULTS: The median numbers of MAs significantly decreased from six (interquartile range [IQR] 3-7) MAs in early-phase FA, three (IQR 3-5) leaky MAs in late-phase FA, and two (IQR 1-4) MAs in late-phase IA at baseline to two (IQR 1-3) MAs in early-phase FA, one (IQR 0-2) leaky MA in late-phase FA, and one (IQR 0-2) MA in late-phase IA at 6 months (P < 0.0001 for all). Only the median numbers of MAs in late-phase IA at baseline and at 6 months were significantly higher in the recurrent DME group (13 eyes) than in the non-recurrent DME group (five eyes) (three [IQR 2-4] vs one [IQR 1-2], one [IQR 0.5-2] vs zero [P = 0.0185 and P = 0.009]). CONCLUSION: Intravitreal injection of anti-VEGF agents reduced the numbers of MAs in patients with DME. The numbers of MAs detected by late-phase IA might be useful predictors of DME recurrence.

Increased expression of periostin and tenascin-C in eyes with neovascular glaucoma secondary to PDR.

PURPOSE: To investigate periostin (PN) and tenascin-C (TNC) expression in the aqueous humor and trabeculectomy specimens of patients with neovascular glaucoma (NVG) secondary to proliferative diabetic retinopathy (PDR). METHODS: This study enrolled 37 eyes of 37 patients who were grouped into (1) NVG secondary to PDR (NVG; n = 8); (2) PDR without NVG (PDR; n = 9); (3) primary open-angle glaucoma (POAG; n = 11); and (4) cataract surgery patients as a control group (CG; n = 9). Aqueous humor samples were collected from the anterior chamber at the start of surgery or intravitreal injection of anti-VEGF drug. The concentrations of PN, TNC, VEGF, and TGF-ß2 (transforming growth factor-beta 2) were measured by ELISA. Sclerostomy tissues containing trabecular meshwork were obtained from two NVG patients and a POAG patient who underwent trabeculectomy surgery. Immunohistochemical analyses were performed to determine the localization of PN and TNC expression in the sclerostomy tissues. RESULTS: PN and TNC-C levels were below detection threshold in the POAG and CG groups. The NVG group had significantly higher levels of PN and TNC compared with the PDR group (84.7 ng/ml vs 2.2 ng/ml and 18.5 ng/ml vs 4.6 ng/ml, respectively; p < 0.05). There was a significant correlation between the levels of PN and TNC-C in the NVG group (r = 0.86, p < 0.05). We found significant expression of PN in the trabecular meshwork and Schlemm's canal of sclerostomy tissues excised from patients with NVG. CONCLUSIONS: Increased PN and TNC expression suggests their possible involvement in the pathogenesis of NVG secondary to PDR.

Periostin in vitreoretinal diseases.

Proliferative vitreoretinal diseases such as diabetic retinopathy, proliferative vitreoretinopathy (PVR), and age-related macular degeneration are a leading cause of decreased vision and blindness in developed countries. In these diseases, retinal fibro(vascular) membrane (FVM) formation above and beneath the retina plays an important role. Gene expression profiling of human FVMs revealed significant upregulation of periostin. Subsequent analyses demonstrated increased periostin expression in the vitreous of patients with both proliferative diabetic retinopathy and PVR. Immunohistochemical analysis showed co-localization of periostin with α-SMA and M2 macrophage markers in FVMs. In vitro, periostin blockade inhibited migration and adhesion induced by PVR vitreous and transforming growth factor-ß2 (TGF-ß2). In vivo, a novel single-stranded RNAi agent targeting periostin showed the inhibitory effect on experimental retinal and choroidal FVM formation without affecting the viability of retinal cells. These results indicated that periostin is a pivotal molecule for FVM formation and a promising therapeutic target for these proliferative vitreoretinal diseases.

Visual Outcomes Based on Early Response to Anti-Vascular Endothelial Growth Factor Treatment for Diabetic Macular Edema.

OBJECTIVE: To examine the relationship between early response to anti-vascular endothelial growth factor (VEGF) treatment and visual prognosis. METHODS: We retrospectively separated 20 patients with persistent diabetic macular edema (DME) into two responder status groups based on the reduction of central macular thickness (CMT) from baseline to month 3: a delayed responder group (DRG) (≤25% CMT reduction, n = 11) and an immediate responder group (IRG) (>25% CMT reduction, n = 14). We also separated the patients into two responder status groups based on the logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA): a visual nonimprovement group (VNIG) (≥0 logMAR BCVA improvement, n = 11) and a vi sual improvement group (VIG) (<0 logMAR BCVA improvement, n = 14). Finally, we assessed the correlations between logMAR BCVA changes from baseline to month 3 (ΔBCVAM3) and those from baseline to month 12 (ΔBCVAM12). RESULTS: At month 12, BCVA was significantly more improved in the VIG than the VNIG (p < 0.005), but was not significantly different between the DRG and the IRG (p = 0.75). The Pearson correlation coefficient showed a significant relationship between ΔBCVAM3 and ΔBCVAM12 (r = 0.60, p < 0.005). CONCLUSIONS: BCVA showed significantly greater improvement in the VIG than in the VNIG. ΔBCVAM3 may predict the visual outcome at month 12 in DME patients treated with anti-VEGF drugs.

αB-Crystallin Regulates Subretinal Fibrosis by Modulation of Epithelial-Mesenchymal Transition.

Subretinal fibrosis is an end stage of neovascular age-related macular degeneration, characterized by fibrous membrane formation after choroidal neovascularization. An initial step of the pathogenesis is an epithelial-mesenchymal transition (EMT) of retinal pigment epithelium cells. αB-crystallin plays multiple roles in age-related macular degeneration, including cytoprotection and angiogenesis. However, the role of αB-crystallin in subretinal EMT and fibrosis is unknown. Herein, we showed attenuation of subretinal fibrosis after regression of laser-induced choroidal neovascularization and a decrease in mesenchymal retinal pigment epithelium cells in αB-crystallin knockout mice compared with wild-type mice. αB-crystallin was prominently expressed in subretinal fibrotic lesions in mice. In vitro, overexpression of αB-crystallin induced EMT, whereas suppression of αB-crystallin induced a mesenchymal-epithelial transition. Transforming growth factor-ß2-induced EMT was further enhanced by overexpression of αB-crystallin but was inhibited by suppression of αB-crystallin. Silencing of αB-crystallin inhibited multiple fibrotic processes, including cell proliferation, migration, and fibronectin production. Bone morphogenetic protein 4 up-regulated αB-crystallin, and its EMT induction was inhibited by knockdown of αB-crystallin. Furthermore, inhibition of αB-crystallin enhanced monotetraubiquitination of SMAD4, which can impair its nuclear localization. Overexpression of αB-crystallin enhanced nuclear translocation and accumulation of SMAD4 and SMAD5. Thus, αB-crystallin is an important regulator of EMT, acting as a molecular chaperone for SMAD4 and as its potential therapeutic target for preventing subretinal fibrosis development in neovascular age-related macular degeneration.

Tenascin-C secreted by transdifferentiated retinal pigment epithelial cells promotes choroidal neovascularization via integrin αV.

Tenascin-C is expressed in choroidal neovascular (CNV) membranes in eyes with age-related macular degeneration (AMD). However, its role in the pathogenesis of CNV remains to be elucidated. Here we investigated the role of tenascin-C in CNV formation. In immunofluorescence analyses, tenascin-C co-stained with α-SMA, pan-cytokeratin, CD31, CD34, and integrin αV in the CNV membranes of patients with AMD and a mouse model of laser-induced CNV. A marked increase in the expression of tenascin-C mRNA and protein was observed 3 days after laser photocoagulation in the mouse CNV model. Tenascin-C was also shown to promote proliferation and inhibit adhesion of human retinal pigment epithelial (hRPE) cells in vitro. Moreover, tenascin-C promoted proliferation, adhesion, migration, and tube formation in human microvascular endothelial cells (HMVECs); these functions were, however, blocked by cilengitide, an integrin αV inhibitor. Exposure to TGF-ß2 increased tenascin-C expression in hRPE cells. Conditioned media harvested from TGF-ß2-treated hRPE cell cultures enhanced HMVEC proliferation and tube formation, which were inhibited by pretreatment with tenascin-C siRNA. The CNV volume was significantly reduced in tenascin-C knockout mice and tenascin-C siRNA-injected mice. These findings suggest that tenascin-C is secreted by transdifferentiated RPE cells and promotes the development of CNV via integrin αV in a paracrine manner. Therefore, tenascin-C could be a potential therapeutic target for the inhibition of CNV development associated with AMD.

Tenascin-C promotes angiogenesis in fibrovascular membranes in eyes with proliferative diabetic retinopathy.

PURPOSE: We previously demonstrated that tenascin-C was highly expressed in the fibrovascular membranes (FVMs) of patients with proliferative diabetic retinopathy (PDR). However, its role in the pathogenesis of FVMs has not been determined. The purpose of this study was to investigate what role tenascin-C plays in the formation and angiogenesis of FVMs. METHODS: The level of tenascin-C was determined by sandwich enzyme-linked immunosorbent assay in the vitreous samples collected from patients with PDR and with a macular hole as control. The locations of tenascin-C, α- smooth muscle actin (SMA), CD34, glial fibrillary acidic protein (GFAP), and integrin αV in the FVMs from PDR patients were determined by immunohistochemistry. We also measured the in vitro expression of the mRNA and protein of tenascin-C in vascular smooth muscle cells (VSMCs) stimulated by interleukin (IL)-13. The effects of tenascin-C on cell proliferation, migration, and tube formation were determined in human retinal endothelial cells (HRECs) in culture. RESULTS: The mean vitreous levels of tenascin-C were significantly higher in patients with PDR than in patients with a macular hole (p<0.001). Double immunofluorescence analyses of FVMs from PDR patients showed that tenascin-C co-stained FVMs with α-SMA, CD34, and integrin αV but not with GFAP. In addition, IL-13 treatment increased both the expression and secretion of tenascin-C by VSMCs in a dose-dependent manner. Tenascin-C exposure promoted proliferation, migration, and tube formation in HRECs. Tenascin-C neutralizing antibody significantly blocked the tube formation by HRECs exposed to VSMC-IL-13-conditioned medium. CONCLUSIONS: Our findings suggest that tenascin-C is secreted from VSMCs and promotes angiogenesis in the FVMs associated with PDR.

Molecular mechanisms of subretinal fibrosis in age-related macular degeneration.

Subretinal fibrosis is a result of a wound healing response that follows choroidal neovascularization in neovascular age-related macular degeneration (nAMD). Although anti-vascular endothelial growth factor therapy has become a standard treatment that improves visual acuity in many nAMD patients, unsuccessful treatment outcomes have often been attributed to the progression of subretinal fibrosis. In this review, we summarize the cellular and extracellular components of subretinal fibrous membranes and also discuss the possible molecular mechanisms including the functional involvement of growth factors and the inflammatory response in the process. Moreover, we present an murine animal model of subretinal fibrosis that might facilitate greater understanding of the pathophysiology and the development of novel therapeutic strategies for the inhibition of subretinal fibrosis in nAMD.

Different roles played by periostin splice variants in retinal neovascularization.

Retinal neovascularization (NV) due to retinal ischemia is one of the major causes of vision reduction in patients with different types of retinal diseases although anti-vascular endothelial growth factor (anti-VEGF) therapy can partially reduce the size of the retinal NV. We recently reported that periostin plays an important role in the development of NV and the formation of preretinal fibrovascular membranes, but the role of the splice variants of periostin on retinal NV has not been determined. We examined the expressions of periostin splice variants in the ischemic retinas of a mouse model of oxygen-induced retinal NV. We also studied the function of periostin splice variants on retinal NV using periostin knock out mice, and the effects of anti-periostin antibodies on retinal NV. Our results showed that the expressions of the periostin splice variants were increased in ischemic retinas. The degree of increase of periostin lacking exon 17 was the highest among the periostin splice variants examined. Both genetic ablation of periostin exons 17 and 21 and antibodies for periostin exons 17 and 21 affected preretinal pathological NV. Inhibition of exon 17 of periostin had the greatest effect in reducing preretinal pathological NV. These findings suggest a causal link between periostin splice variants and retinal NV, and an intravitreal injection of antibody for exon 17 and exon 21 of periostin should be considered to inhibit preretinal pathological NV.

SIRT1 mediated inhibition of VEGF/VEGFR2 signaling by Resveratrol and its relevance to choroidal neovascularization.

SIRT1, a NAD(+) -dependent histone deacetylase, has been shown to act as a key regulator of angiogenesis. The purpose of this study was to determine the effects of resveratrol (RSV, a SIRT1 activator) on the vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathway and to establish its relevance to choroidal neovascularization (CNV), a blinding complication of age-related macular degeneration. Western blot and ELISA assay showed that RSV inhibited hypoxia-inducible factor (HIF)-1α accumulation and VEGF secretion induced by cobalt chloride (CoCl2) through SIRT1 in human retinal pigment epithelial (hRPE) cells. Furthermore, RSV down-regulated VEGFR2 phosphorylation and activation induced by VEGF in endothelial cells via SIRT1. Thus, the inhibitory effect of RSV on the HIF-1α/VEGF/VEGFR2 signaling axis is mediated, at least in part, through SIRT1. The results suggest that targeting SIRT1 could have therapeutic potential for the treatment of CNV.

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 tractional 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 αV-mediated FAK and AKT phosphorylation. Periostin blockade suppressed migration and adhesion induced by TGFß2 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.

[Periostin in the Pathogenesis of Proliferative Vitreoretinopathy].

Proliferative vitreoretinopathy (PVR) is a serious complication of retinal detachment and vitreoretinal surgery. The hallmark of PVR is the formation of subretinal and epiretinal fibrotic membranes that can lead to traction retinal detachment due to their contractile properties. Surgical removal of the fibrotic membranes and retinal detachment repair are the first choice treatments for PVR. Despite recent progress in surgical techniques, recurrent detachment can lead to irreversible damage and a poor prognosis for visual acuity. Therefore, it is important to develop new molecular targeting therapies based on the exact pathogenesis of PVR. In order to determine the genes responsible for development of PVR, we performed gene expression profiling of fibrous membranes excised from PVR patients using DNA microarray analysis. This analysis revealed significant up-regulation of periostin. We also found increased periostin expression in the vitreous and retinal pigment epithelial (RPE) cells in fibrous membranes of PVR patients. In vitro, periostin increased proliferation, adhesion, migration and collagen production in primary human RPE cells through integrin αV-mediated FAK and AKT phosphorylation. Blockade of periostin suppressed migration and adhesion induced by TGF-ß2 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 the novel causal link between periostin and the generation of PVR membranes as well as a promising therapeutic target for PVR.