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.

Comparación de la efectividad de ranibizumab intravítreo para el tratamiento del edema macular diabético en ojos vitrectomizados y no vitrectomizados.

Objetivo: Comparar la efectividad de ranibizumab intravítreo (RIV) para el tratamiento del edema macular diabético (EMD) en ojos con y sin vitrectomía previa. Procedimientos: Evaluamos de manera prospectiva la mejor agudeza visual corregida (MAVC) y el grosor macular central (GMC) tras el tratamiento con RIV durante 6 meses. Resultados: No se observaron diferencias significativas en la MAVC o GMC inicial en ninguno de los dos grupos. En el grupo no vitrectomizado (n = 15), los cambios medios en la MAVC y GMC hasta el sexto mes de tratamiento con respecto al valor inicial resultaron significativos (p < 0,01). En el grupo vitrectomizado (n = 10), se observó una mejora más lenta, y la mejora media en la MAVC no resultó significativa (p = 0,5), aunque la media en la disminución del GMC sí que lo fue (p < 0,05). No se observaron diferencias significativas en los cambios medios en la MAVC y el GMC entre ambos grupos a los 6 meses del tratamiento. Conclusiones: La diferencia en la efectividad de RIV entre ambos grupos no resultó significativa. Ranibizumab intravítreo puede ser una opción de tratamiento incluso en pacientes vitrectomizados con EMD.

A Case of Diabetic Macular Edema with Improvement in Severity of Diabetic Retinopathy following Frequent Anti-Vascular Endothelial Growth Factor Treatment.

Background: Intravitreal anti-vascular endothelial growth factor (VEGF) drug injections are the gold standard for the treatment of diabetic macular edema (DME). We report a case of DME in which frequent anti-VEGF treatment resulted in improvement of diabetic retinopathy. Case: A 73-year old woman with DME who had previously undergone bilateral posterior subtenon injections of triamcinolone acetonide and vitrectomy OD presented at Kyushu University Hospital. Best corrected visual acuity was 0.1 OD and 0.15 OS. The central macular thickness was 1570 µm OD and 578 µm OS. We performed focal macular laser photocoagulation OU but the DME was not resolved. Subsequent intravitreal anti-VEGF drug injections(approximately 20 times/2 years)resulted in an improvement of the best corrected visual acuity (0.3 OD, 0.6 OS) and CMT (1570 µm OD, 578 µm OS). There was an improvement of 2 steps in the Diabetic Retinopathy Severity Scale (DRSS) score OU. Conclusion: Frequent anti-VEGF treatment can improve the severity of diabetic retinopathy.

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.

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.

Comparison of the Effectiveness of Intravitreal Ranibizumab for Diabetic Macular Edema in Vitrectomized and Nonvitrectomized Eyes.

PURPOSE: To compare the effectiveness of intravitreal ranibizumab (IVR) for diabetic macular edema (DME) between eyes with and without previous vitrectomy. PROCEDURES: We prospectively assessed the best-corrected visual acuity (BCVA) and central macular thickness (CMT) after IVR for 6 months. RESULTS: There were no significant differences in the baseline BCVA and CMT between both groups. In the nonvitrectomized group (n = 15), the mean changes of BCVA and CMT from baseline to month 6 were significant (p < 0.01). In the vitrectomized group (n = 10), the improvement appeared to be slower, and the mean BCVA improvement was not significant (p = 0.5), although the mean CMT decrease was significant (p < 0.05). There were no significant differences in the mean changes of BCVA and CMT between both groups at 6 months. CONCLUSIONS: The difference in the effectiveness of IVR between both groups was not significant. IVR can be a treatment option even for vitrectomized DME eyes.

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.

Clinical Characteristics of Eyes with Neovascular Age-Related Macular Degeneration and Retinal Pigment Epithelium Tears.

BACKGROUND: Although anti-vascular endothelial growth factor (anti-VEGF) therapy is the first choice of treatment for eyes with neovascular age-related macular degeneration (AMD), it sometimes results in retinal pigment epithelium (RPE) tears. This study presents the detailed clinical characteristics of RPE tears to help predict their occurrence before anti-VEGF therapy initiation. METHODS: This study retrospectively analyzed neovascular age-related macular degeneration (nAMD) patients who visited the Kyushu University Hospital and started anti-VEGF therapy between April 2013 and June 2020. Using medical records, we collected the clinical data of patients with RPE tears, including age, sex, best-corrected visual acuity (BCVA), number of anti-VEGF drug injections and the type and size of pigment epithelial detachment (PED). RESULTS: RPE tears occurred in 16 (1.50%) eyes of 16 patients in all 1068 nAMD eyes of 987 patients. The mean age of these patients with RPE tear was 81.7 ± 8.7 years. Fifteen eyes had typical AMD and one eye had polypoidal choroidal vasculopathy. The mean number of anti-VEGF drug injections before RPE tears was 5.0 ± 5.1. All patients experienced PED before the RPE tear (hemorrhagic, 4 eyes; serous vascular, 2 eyes; fibrovascular, 10 eyes). The average PED height and area were 615.7 ± 175.3 µm and 21.0 ± 7.2 mm2, respectively. The sub-RPE cleft was observed in 10 eyes. The logMAR BCVA immediately after the RPE tear (0.73 ± 0.40) at 6 months (0.86 ± 0.51) and 12 months (0.84 ± 0.43) after the RPE tear were significantly worse than that before the RPE tear (0.58 ± 0.31; p < 0.05). The BCVA of patients with RPE tears that spread to the fovea was poorer than that of patients without RPE tears. CONCLUSIONS: In patients with nAMD, RPE tears tended to occur in typical AMD eyes with high or large PEDs, and sub-RPE clefts. The visual prognosis depended on whether the RPE tear included the fovea.

Drainage Retinotomy Confers Risk of Epiretinal Membrane Formation After Vitrectomy for Rhegmatogenous Retinal Detachment Repair.

PURPOSE: To describe the factors associated with epiretinal membrane (ERM) formation in eyes treated with pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD). DESIGN: Nationwide, multicenter, clinical cohort study based on registry data. METHODS: We reviewed 2239 cases treated with PPV for RRD repair registered in the Japan-Retinal Detachment Registry between February 2016 and March 2017. Associations of 13 baseline characteristics and 8 surgical procedures with ERM formation were evaluated using univariate analysis. We conducted a propensity score-matched analysis for the significantly associated clinical factor(s). The primary outcome measure was ERM formation after 6 months of vitrectomy. RESULTS: ERM had developed in 104 cases (4.6%) by 6 months. We found that drainage retinotomy was significantly associated with ERM after multiple testing correction (odds ratio [OR] 2.22 [95% confidence interval {CI} 1.50-3.31]; P < .001). In the propensity score-matched analysis (n = 492 in each group), we confirmed a significant difference in the incidence of ERM after 6 months of vitrectomy (8.3% and 2.6% in cases with and without drainage retinotomy, respectively; OR 3.35 [95% CI 1.77-6.33]; P < .001). CONCLUSIONS: Eyes treated with PPV combined with drainage retinotomy are more likely to develop ERM postoperatively.

Identifying Hyperreflective Foci in Diabetic Retinopathy via VEGF-Induced Local Self-Renewal of CX3CR1+ Vitreous Resident Macrophages.

Intraretinal hyperreflective foci (HRF) are significant biomarkers for diabetic macular edema. However, HRF at the vitreoretinal interface (VRI) have not been examined in diabetic retinopathy (DR). A prospective observational clinical study with 162 consecutive eyes using OCT imaging showed significantly increased HRF at the VRI during DR progression (P < 0.01), which was reversed by anti-vascular endothelial growth factor (VEGF) therapy. F4/80+ macrophages increased significantly at the VRI in Kimba (vegfa+/+) or Akimba (Akita × Kimba) mice (both P < 0.01), but not in diabetic Akita (Ins2+/-) mice, indicating macrophage activation was modulated by elevated VEGF rather than the diabetic milieu. Macrophage depletion significantly reduced HRF at the VRI (P < 0.01). Furthermore, BrdU administration in Ccr2rfp/+Cx3cr1gfp/+vegfa+/- mice identified a significant contribution of M2-like tissue-resident macrophages (TRMs) at the VRI. Ki-67+ and CD11b+ cells were observed in preretinal tissues of DR patients, while exposure of vitreal macrophages to vitreous derived from PDR patients induced a significant proliferation response in vitro (P < 0.01). Taken together, the evidence suggests that VEGF drives a local proliferation of vitreous resident macrophages (VRMs) at the VRI during DR. This phenomenon helps to explain the derivation and disease-relevance of the HRF lesions observed through OCT imaging in patients.

Risk factors for myopia at 1-year corrected age following laser photocoagulation for retinopathy of prematurity.

BACKGROUND/OBJECTIVES: The prevalence of myopia is higher in preterm infants who underwent laser photocoagulation (LPC) for retinopathy of prematurity (ROP). The aim of this study was to investigate factors associated with myopia in preterm infants who undergo LPC for ROP. SUBJECTS/METHODS: We retrospectively analysed the medical records of preterm infants born at Kyushu University Hospital (October 2008-March 2018) at ≤32 weeks of gestational age or with birth weight ≤1500 g. We evaluated the associations between nine clinical factors and the spherical equivalent at 1-year corrected age by performing multivariable linear regression in LPC-treated ROP patients. RESULTS: Among the 485 infants enroled, 76 developed ROP requiring treatment. Of these, 71 underwent LPC, which was provided to 63 infants as the primary treatment (LPC alone or the combination therapy of LPC and intravitreal injection of bevacizumab [IVB]) and to eight infants as additional LPC after IVB monotherapy. The results of a refractive examination at 1-year corrected age were available for 110 eyes of 56 infants (78.9%). The mean ± standard deviation of the SE value was -0.5 ± 3.0 dioptres (D). Multivariable linear regression analysis revealed a significant association between laser spot count and SE value (ß = -0.081 ± 0.040 D per 100 spots [mean ± standard error], p = 0.045). CONCLUSIONS: Our results suggest that an increased laser spot count observed during ROP treatment associates with myopia.

Changes in metamorphopsia after the treat-and-extend regimen of anti-VEGF therapy for macular edema associated with branch retinal vein occlusion.

This study aims to investigate the changes in metamorphopsia after administering the treat-and-extend regimen of anti-vascular endothelial growth factor therapy for branch retinal vein occlusion-associated macular edema. We retrospectively examined 27 patients (27 eyes) with macula edema due to branch retinal vein occlusion who received intravitreal injections of anti-vascular endothelial growth factor agents using the treat-and-extend regimen for ≥18 months. We evaluated best-corrected visual acuity, central macular thickness, macular edema recurrence, and amount of metamorphopsia quantified by M-CHARTS. The best-corrected visual acuity (logarithm of minimum angle of resolution) and central macular thickness significantly improved at 18 months compared to baseline, the median value (interquartile range [IQR]), 0.30 (0.15-0.52) and 459 (373-542) µm at baseline, and 0 (-0.08-0.16) and 267 (232-306) µm at 18 months. The M-CHARTS score (the mean of vertical and horizontal scores) significantly decreased at 1, 6, and 12 months compared to baseline, but worsened at 18 month, the median value (IQR), 0.45 (0.250-0.925), 0.4 (0.15-0.70), 0.4 (0.150-0.625), 0.4 (0.225-0.550) and 0.45 (0.225-0.750) at baseline, 1 month, 6 months, 12 months and 18 months, respectively. The median cumulative number of macular edema recurrences was 2 (IQR, 0.5-3.0) at 18 months. Simple linear regression and multivariate analyses revealed that the change in the mean M-CHARTS score at 18 months was significantly correlated with the baseline score and the cumulative number of macular edema recurrences. Anti-vascular endothelial growth factor therapy using the treat-and-extend regimen improved metamorphopsia in branch retinal vein occlusion-related macular edema in the short to mid-term follow-up period, but not in the long term. Macular edema recurrence may be associated with persistent metamorphopsia.

Neurodevelopmental outcomes following intravitreal bevacizumab injection in Japanese preterm infants with type 1 retinopathy of prematurity.

PURPOSE: The purpose of this study was to evaluate neurodevelopmental outcomes in 18-month old (corrected age) preterm infants who received an intravitreal bevacizumab (IVB) injection for the treatment of type 1 retinopathy of prematurity (ROP). METHODS: In this ten-year retrospective study, we reviewed the medical records of patients who underwent ROP screening at Kyushu University Hospital. Among the patients who received IVB or laser photocoagulation (LPC) for the treatment of type 1 ROP, we included infants whose neurodevelopmental examination (the Kyoto Scale of Psychological Development [KSPD]) results at 18 months corrected age were available. Then, the effect of IVB on the developmental quotient (DQ) in each KSPD domain (Postural-Movement, Cognitive-Adaptive, or Language-Social domain) or the overall DQ was investigated by performing linear regression analysis. RESULTS: Out of the 513 patients reviewed, 53 were included in the study. IVB and LPC were performed for 14 and 39 patients, respectively. Administration of IVB was significantly associated with neurodevelopmental delay in the Language-Social domain (p = 0.01). The observed association remained even after adjusting for gestational age and birth weight (p = 0.03). CONCLUSIONS: Administration of IVB may introduce a risk of developmental impairment of interpersonal relationships, socializations, and/or verbal abilities of preterm children. We recommended that preterm infants who received IVB undergo a neurodevelopmental reassessment during their school years or in adulthood.

Periostin and tenascin-C interaction promotes angiogenesis in ischemic proliferative retinopathy.

Ischemic proliferative retinopathy (IPR), such as proliferative diabetic retinopathy (PDR), retinal vein occlusion and retinopathy of prematurity is a major cause of vision loss. Our previous studies demonstrated that periostin (PN) and tenascin-C (TNC) are involved in the pathogenesis of IPR. However, the interactive role of PN and TNC in angiogenesis associated with IPR remain unknown. We found significant correlation between concentrations of PN and TNC in PDR vitreous humor. mRNA and protein expression of PN and TNC were found in pre-retinal fibrovascular membranes excised from PDR patients. Interleukin-13 (IL-13) promoted mRNA and protein expression of PN and TNC, and co-immunoprecipitation assay revealed binding between PN and TNC in human microvascular endothelial cells (HRECs). IL-13 promoted angiogenic functions of HRECs. Single inhibition of PN or TNC and their dual inhibition by siRNA suppressed the up-regulated angiogenic functions. Pathological pre-retinal neovessels of oxygen-induced retinopathy (OIR) mice were attenuated in PN knock-out, TNC knock-out and dual knock-out mice compared to wild-type mice. Both in vitro and in vivo, PN inhibition had a stronger inhibitory effect on angiogenesis compared to TNC inhibition, and had a similar effect to dual inhibition of PN and TNC. Furthermore, PN knock-out mice showed scant TNC expression in pre-retinal neovessels of OIR retinas. Our findings suggest that interaction of PN and TNC facilitates pre-retinal angiogenesis, and PN is an effective therapeutic target for IPR such as PDR.

Attenuation of periostin in retinal Müller glia by TNF-α and IFN-γ.

AIM: To investigate the regulation and mechanisms of periostin expression in retinal Müller glia, and to explore the relevance to retinal neovascularization. METHODS: The oxygen-induced retinopathy (OIR) mouse model and the human Moorfield/Institute of Ophthalmology-Müller 1 (MIO-M1) cell line were used in the study. Immunofluorescence staining was used to determine the distribution and expression of periostin and a Müller glial cell marker glutamine synthetase (GS). Cytokines TNF-α and IFN-γ were added to stimulate the MIO-M1 cells. ShRNA was used to knockdown periostin expression in MIO-M1 cells. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) was conducted to assess the mRNA expression of periostin. RESULTS: Immunofluorescence staining showed that periostin was expressed by MIO-M1 Müller glia. GS-positive Müller glia and periostin increased in OIR retinas, and were partially overlaid. The stimulation of TNF-α and IFN-γ reduced the mRNA expression of periostin significantly and dose-dependently in MIO-M1 cells. Knockdown of periostin reduced mRNA expression of vascular endothelial growth factor A (VEGFA) in MIO-M1 cells, while VEGFA expression was not changed in periostin knock-out OIR retinas. CONCLUSION: Müller glia could be one of the main sources of periostin in the retina, and might contribute to the pathogenesis of retinal neovascularization. Proinflammatory cytokines TNF-α and IFN-γ attenuate the periostin expression in retinal Müller glia, which provides a potential and novel method in treating retinal neovascular diseases.

Leukotriene B4 promotes neovascularization and macrophage recruitment in murine wet-type AMD models.

Age-related macular degeneration (AMD), a progressive chronic disease of the central retina, is associated with aging and is a leading cause of blindness worldwide. Here, we demonstrate that leukotriene B4 (LTB4) receptor 1 (BLT1) promotes laser-induced choroidal neovascularization (CNV) in a mouse model for wet-type AMD. CNV was significantly less in BLT1-deficient (BLT1-KO) mice compared with BLT1-WT controls. Expression of several proangiogenic and profibrotic factors was lower in BLT1-KO eyes than in BLT1-WT eyes. LTB4 production in the eyes was substantially increased in the early phase after laser injury. BLT1 was highly expressed in M2 macrophages in vitro and in vivo, and ocular BLT1+ M2 macrophages were increased in the aged eyes after laser injury. Furthermore, M2 macrophages were rapidly attracted by LTB4 and subsequently produced VEGF-A- through BLT1-mediated signaling. Consequently, intravitreal injection of M2 macrophages augmented CNV formation, which was attenuated by BLT1 deficiency. Thus, laser-induced injury to the retina triggered LTB4 production and attracted M2 macrophages via BLT1, leading to development of CNV. A selective BLT1 antagonist (CP105696) and 3 LTB4 inhibitors (zileuton, MK-886, and bestatin) reduced CNV in a dose-dependent manner. CP105696 also inhibited the accumulation of BLT1+ M2 macrophages in the laser-injured eyes of aged mice. Together, these results indicate that the LTB4-BLT1 axis is a potentially novel therapeutic target for CNV of wet-type AMD.

Different distributions of M1 and M2 macrophages in a mouse model of laser-induced choroidal neovascularization.

Choroidal neovascularization (CNV) is a serious complication of age­related macular degeneration. The aim of the present study was to investigate the expression and distribution of M1 and M2 macrophages in a laser­induced CNV adult mouse model. The mRNA expression levels of M1, M2 and pan macrophage markers, and macrophage­associated angiogenic cytokines, were determined by reverse transcription­quantitative polymerase chain reaction. Immunofluorescence studies were performed to determine the location of the macrophages. The expression levels of M1 macrophage markers increased to a greater extent compared with M2 markers in the retinal pigment epithelium (RPE)­choroid complexes following laser photocoagulation. By contrast, the expression levels of M2 macrophage markers increased primarily in the retinas. Immunofluorescence studies revealed that the increased number of cluster of differentiation (CD)206­positive cells were located primarily in the retina, whereas the CD80­positive cells were located around the site of CNVs in the RPE­choroid. In addition, the M1­associated cytokines increased to a greater extent in the RPE­choroid complexes, whereas the M2­associated cytokines were highly expressed in the retinas. These findings indicate that M1 and M2 macrophage numbers increased following CNV; however, the locations were different in this mouse model of laser­induced CNV. The results of the present study suggest that M1 macrophages have a more direct role in inhibiting the development of CNV.

Therapeutic Effect of Novel Single-Stranded RNAi Agent Targeting Periostin in Eyes with Retinal Neovascularization.

Retinal neovascularization (NV) due to retinal ischemia remains one of the principal causes of vision impairment in patients with ischemic retinal diseases. We recently reported that periostin (POSTN) may play a role in the development of preretinal fibrovascular membranes, but its role in retinal NV has not been determined. The purpose of this study was to examine the expression of POSTN in the ischemic retinas of a mouse model of oxygen-induced retinal NV. We also studied the function of POSTN on retinal NV using Postn KO mice and human retinal endothelial cells (HRECs) in culture. In addition, we used a novel RNAi agent, NK0144, which targets POSTN to determine its effect on the development of retinal NV. Our results showed that the expression of POSTN was increased in the vascular endothelial cells, pericytes, and M2 macrophages in ischemic retinas. POSTN promoted the ischemia-induced retinal NV by Akt phosphorylation through integrin αvß3. NK0144 had a greater inhibitory effect than canonical double-stranded siRNA on preretinal pathological NV in vivo and in vitro. These findings suggest a causal relationship between POSTN and retinal NV, and indicate a potential therapeutic role of intravitreal injection of NK0144 for retinal neovascular diseases.