Comparison of Scheimpflug and Anterior Segment Optical Coherence Tomography Imaging Parameters for Japanese Patients With Fuchs Endothelial Corneal Dystrophy With and Without TCF4 Repeat Expansions.

PURPOSE: The aim of this study was to investigate the association between cytosine-thymine-guanine trinucleotide repeat (TNR) expansion in TCF4 and the clinical phenotypes of corneal densitometry or anterior segment morphology in Fuchs endothelial corneal dystrophy. METHODS: This retrospective cross-sectional study included 150 eyes from 75 Japanese consecutive patients with Fuchs endothelial corneal dystrophy. Cytosine-thymine-guanine repeat expansion of leukocyte-derived genomic DNA was analyzed through fragment analysis using polymerase chain reaction and triplet repeat primed polymerase chain reaction. Scheimpflug-based densitometry and anterior segment optical coherence tomography were applied. Corneal densitometry, and corneal and anterior segment morphology parameters were compared between patients with and without TNR expansion of 50 or more (expansion and nonexpansion groups, respectively) using a mixed model. RESULTS: The average age of the patients was 66.8 ± 13.0 years, and the modified Krachmer grading scale was 1, 2, 3, 4, 5, and 6 for 7, 32, 28, 51, 6, and 18 eyes, respectively. Sixteen patients (21%) exhibited ≥50 TNR expansion. No significant differences in sex, age, history of keratoplasty, modified Krachmer grade, and corneal densitometry in either diameter or depth were observed between the 2 groups. No significant differences in anterior segment morphology, including the anterior chamber depth and anterior chamber angle width parameters, were observed using a univariate mixed model, except for central corneal thickness (P = 0.047). However, according to the multivariate mixed model, repeat expansion was not significantly associated with central corneal thickness (P = 0.27). CONCLUSIONS: No significant differences in clinical phenotypes were found between Japanese patients having Fuchs endothelial corneal dystrophy with and without TNR expansion.

Two Japanese Families with Pigmented Paravenous Retinochoroidal Atrophy and HK1 Mutation: A Case Report.

Hexokinase 1 (HK1) gene is the cause of autosomal dominant retinitis pigmentosa (RP) 79. To date, only E874K mutation has been reported as the causative mutation in patients with nonsyndromic RP. As a Caucasian RP case with a pathological variant of HK1 exhibiting pigmented paravenous retinochoroidal atrophy (PPRCA) phenotype was recently reported, we reviewed RP79 cases in our Japanese RP cohort. Consequently, 2 Japanese patients, who were diagnosed with RP79 by genetic tests in our RP cohort, were included in this study. Patient 1 was a 60-year-old woman. Fundus examination revealed symmetrical donut-shaped retinal degeneration, with pigment deposition avoiding the macula. Moreover, degeneration extended in a peripheral direction along the vessels like a starfish, and degeneration was observed around the veins and arteries. Patient 2 was a 75-year-old man. Fundus examination revealed symmetric macula-avoiding donut-shaped retinal degeneration, with paravenous protruding degeneration along the blood vessels like in case 1. Both Japanese cases, which belonged to two separate families, had the same HK1 pathogenic mutation, with a phenotype of PPRCA. Furthermore, atrophy along retinal arteries was noted. Reviewing previous nonsyndromic RP79 cases revealed symptoms that are believed to be those of PPRCA. Ultra-widefield fundus imaging, especially ultra-widefield fundus autofluorescence, has been useful in detecting PPRCA. If these devices become widely available, more cases may be discovered in the future because PPRCA can be used as a clue to suspect RP79, and Sanger sequencing may be used to identify pathogenic mutations in HK1 at a lower cost and more easily than using whole-exome sequencing.

PAX6-positive microglia evolve locally in hiPSC-derived ocular organoids.

Microglia are the resident immune cells of the central nervous system (CNS). They govern the immunogenicity of the retina, which is considered to be part of the CNS; however, it is not known how microglia develop in the eye. Here, we studied human-induced pluripotent stem cells (hiPSCs) that had been expanded into a self-formed ectodermal autonomous multi-zone (SEAM) of cells that partially mimics human eye development. Our results indicated that microglia-like cells, which have characteristics of yolk-sac-like linage cells, naturally develop in 2D eye-like SEAM organoids, which lack any vascular components. These cells are unique in that they are paired box protein 6 (PAX6)-positive, yet they possess some characteristics of mesoderm. Collectively, the data support the notion of the existence of an isolated, locally developing immune system in the eye, which is independent of the body's vasculature and general immune system.

Extensive Macular Atrophy with Pseudodrusen in a Japanese Patient Evaluated by Wide-Field OCTA.

Extensive macular atrophy with pseudodrusen (EMAP) is a relatively newly proposed clinical entity that was first reported in 2009. Although no definitive diagnostic criteria have been defined, characteristic findings can distinguish it from other diseases, especially dry age-related macular dystrophy (AMD). Herein, we present the case of a patient with EMAP who underwent a comprehensive ophthalmic examination and whole-exome sequencing (WES). A 72-year-old Japanese man complained of progressive visual impairment in his right eye and nyctalopia. Ophthalmic examination revealed that the best-corrected visual acuity (BCVA) in decimal units was 0.08 on the right and 0.8 on the left. Fundoscopy and fundus autofluorescence (FAF) revealed well-demarcated symmetrical macular atrophy, with a vertical axis larger than the horizontal axis, which reached the vascular arcade inferiorly and exceeded it superiorly. Pseudodrusen were widespread throughout the retina in both eyes. Paving-stone degeneration was not observed in the extreme periphery of either eye. Seven months later, his left BCVA decreased to 0.3 without major changes on multimodal imaging. Based on the above findings, we diagnosed EMAP. Wide-field optical coherence tomography angiography (OCTA) showed no significant changes in the retinal vessels, but the density of choroidal vessels was reduced in the degenerated areas. We thought that this finding suggests that EMAP originates between the deep retina and choroid. WES did not reveal any candidate mutations in known pathogenic genes. To the best of our knowledge, this is the first report of a Japanese patient with EMAP, and no data for analysis of wide-field OCTA or equatorial OCT images of EMAP cases have been found in previous reports. EMAP is not well recognized in Asia and may be incorrectly diagnosed as dry-type AMD. EMAP should be included in the differential diagnosis of dry AMD, and this may lead to more Asians being diagnosed with EMAP in the future.

Human iPS cells engender corneal epithelial stem cells with holoclone-forming capabilities.

Human induced pluripotent stem cells (hiPSCs) can generate a multiplicity of organoids, yet no compelling evidence currently exists as to whether or not these contain tissue-specific, holoclone-forming stem cells. Here, we show that a subpopulation of cells in a hiPSC-derived corneal epithelial cell sheet is positive for ABCB5 (ATP-binding cassette, sub-family B, member 5), a functional marker of adult corneal epithelial stem cells. These cells possess remarkable holoclone-forming capabilities, which can be suppressed by an antibody-mediated ABCB5 blockade. The cell sheets are generated from ABCB5+ hiPSCs that first emerge in 2D eye-like organoids around six weeks of differentiation and display corneal epithelial immunostaining characteristics and gene expression patterns, including sustained expression of ABCB5. The findings highlight the translational potential of ABCB5-enriched, hiPSC-derived corneal epithelial cell sheets to recover vision in stem cell-deficient human eyes and represent the first report of holoclone-forming stem cells being directly identified in an hiPSC-derived organoid.

Drug screening with zebrafish visual behavior identifies carvedilol as a potential treatment for an autosomal dominant form of retinitis pigmentosa.

Retinitis Pigmentosa (RP) is a mostly incurable inherited retinal degeneration affecting approximately 1 in 4000 individuals globally. The goal of this work was to identify drugs that can help patients suffering from the disease. To accomplish this, we screened drugs on a zebrafish autosomal dominant RP model. This model expresses a truncated human rhodopsin transgene (Q344X) causing significant rod degeneration by 7 days post-fertilization (dpf). Consequently, the larvae displayed a deficit in visual motor response (VMR) under scotopic condition. The diminished VMR was leveraged to screen an ENZO SCREEN-WELL REDOX library since oxidative stress is postulated to play a role in RP progression. Our screening identified a beta-blocker, carvedilol, that ameliorated the deficient VMR of the RP larvae and increased their rod number. Carvedilol may directly on rods as it affected the adrenergic pathway in the photoreceptor-like human Y79 cell line. Since carvedilol is an FDA-approved drug, our findings suggest that carvedilol can potentially be repurposed to treat autosomal dominant RP patients.

A hypomorphic variant in EYS detected by genome-wide association study contributes toward retinitis pigmentosa.

The genetic basis of Japanese autosomal recessive retinitis pigmentosa (ARRP) remains largely unknown. Herein, we applied a 2-step genome-wide association study (GWAS) in 640 Japanese patients. Meta-GWAS identified three independent peaks at P < 5.0 × 10-8, all within the major ARRP gene EYS. Two of the three were each in linkage disequilibrium with a different low frequency variant (allele frequency < 0.05); a known founder Mendelian mutation (c.4957dupA, p.S1653Kfs*2) and a non-synonymous variant (c.2528 G > A, p.G843E) of unknown significance. mRNA harboring c.2528 G > A failed to restore rhodopsin mislocalization induced by morpholino-mediated knockdown of eys in zebrafish, consistent with the variant being pathogenic. c.2528 G > A solved an additional 7.0% of Japanese ARRP cases. The third peak was in linkage disequilibrium with a common non-synonymous variant (c.7666 A > T, p.S2556C), possibly representing an unreported disease-susceptibility signal. GWAS successfully unraveled genetic causes of a rare monogenic disorder and identified a high frequency variant potentially linked to development of local genome therapeutics.

Identification of TIE2 as a susceptibility gene for neovascular age-related macular degeneration and polypoidal choroidal vasculopathy.

PURPOSE: The endothelial and cell-specific angiopoietin-Tie pathway plays an important regulatory role in angiogenesis. In this study, we investigated the associations of the TIE2 (tyrosine kinase, endothelial, TEK) gene with neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV), using haplotype-tagging single-nucleotide polymorphisms (SNPs) analysis. METHODS: This study involved totally 2343 subjects, including a Hong Kong Chinese cohort (214 nAMD patients, 236 PCV patients and 433 control subjects), a Shantou Chinese cohort (189 nAMD patients, 187 PCV patients and 531 control subjects) and an Osaka Japanese cohort (192 nAMD patients, 204 PCV patients and 157 control subjects). Thirty haplotype-tagging SNPs in TIE2 were genotyped in the Hong Kong cohort using TaqMan technology. Two SNPs (rs625767 and rs2273717) showing association in the Hong Kong cohort were genotyped in the Shantou and Osaka cohorts. The SNP-disease association of individual and pooled cohorts were analysed. RESULTS: Two SNPs (rs625767 and rs2273717) showed suggestive association with both nAMD and PCV in the Hong Kong cohort. In the meta-analysis involving all the three cohorts, rs625767 showed significant associations with nAMD (p=0.01; OR=0.82, 95% CI 0.70 to 0.96; I2=0%), PCV (p=0.02; OR=0.83, 95% CI 0.71 to 0.97; I2=27%) and pooled nAMD and PCV (p=0.002; OR=0.82, 95% CI 0.72 to 0.93; I2=0%), with low inter-cohort heterogeneities. CONCLUSION: This study revealed TIE2 as a novel susceptibility gene for nAMD and PCV in Japanese and Chinese. Further studies in other populations are warranted to confirm its role.

Corneal Opacity Induced by Light in a Mouse Model of Gelatinous Drop-Like Corneal Dystrophy.

Gelatinous drop-like corneal dystrophy (GDLD) is a severe inherited corneal dystrophy characterized by subepithelial corneal amyloid deposition. We had previously succeeded in identifying the responsible gene, TACSTD2, and subsequently found that the epithelial barrier function is significantly decreased. As with GDLD patients, the knockout mice showed severe loss of tight junction, progressive opacity, and neovascularization in the cornea. We devised an easy method to confirm the loss of the corneal barrier function even before corneal opacity is observed. Furthermore, by using knockout mice, we were able to verify clinical findings, such as the wound healing delay and light-induced acceleration of the disease. This mouse model should prove to be a highly useful tool for investigating the pathology of GDLD and for developing new therapies.

Novel mutation identified in Leber congenital amaurosis - a case report.

BACKGROUND: Leber congenital amaurosis (LCA) is the earliest onset and the most severe form of all inherited retinal degenerative disorders, characterized by blindness, or severe visual impairment from birth, and typically exhibits clinical and genetic heterogeneity. Recently, 14 causative genes of LCA were reported. We performed whole-exome sequencing (WES) for Japanese siblings, and identified a novel homozygous nonsense mutation in the RPGR-interacting protein 1 (RPGRIP1) gene. We also report their follow-up data over 27 years. CASE PRESENTATION: Patient 1 is a 37-year-old male. In 1992, his eye position indicated orthophoria, however, horizontal nystagmus was evident, and he complained of photophobia. His best corrected decimal visual acuity (BCVA) was 0.2 (S + 6.5/C-3.5/170°) OD and 0.1 (S + 6.0/C-2.5/10°) OS. Fundus examination revealed bisymmetrical inferior focal retinal pigment epithelium (RPE) mottling. Bright-flash electroretinogram (ERG) revealed a subnormal pattern, while 30 Hz flicker ERG was non-recordable in both eyes. At his final visit in 2019, his BCVA was 0.09 (S + 3.5/C-3.5/180°) OD and 0.09 (S + 3.0/C-4.0/10°) OS. Patient 2, a 34-year-old female, is the sibling of patient 1. In 1992, her BCVA was 0.05 (S + 6.0) OD and 0.06 (S + 5.0) OS. She was in a chin-up position during visual acuity testing. Horizontal nystagmus was evident, and she also complained of photophobia. Bright-flash ERG was severely attenuated, and 30 Hz flicker ERG was non-recordable in both eyes. At her final visit in 2019, her BCVA was 0.02 (uncorrectable) OD and 0.03 (uncorrectable) OS. There were no other patients with LCA in their family and their parents were non-consanguineous. WES revealed a homozygous, consecutive, two-nucleotide variation in the RPGRIP1 gene (NM_020366: exon15:c.G2294A and c.C2295A, p.C765X), resulting in a premature stop codon. We interpreted this variation as a novel pathogenic mutation of RPGRIP1 that contributes to LCA6 development. CONCLUSIONS: Herein, we report a novel nonsense mutation of RPGRIP1 in two patients with LCA6 and present their long-term follow-up data. These clinical data linked to genotypes provide important information for the development of new treatments, such as gene therapy, as well as for genetic counseling.

Quantitative Analysis of the Association Between Follow-Up Duration and Severity of Limbal Stem Cell Deficiency or Visual Acuity in Aniridia.

Purpose: This study aimed to quantitatively analyze the association between follow-up duration and the severity of limbal stem cell deficiency (LSCD) or visual acuity in patients with aniridia. Methods: A total of 52 eyes of 27 patients with aniridia were enrolled at Osaka University Hospital. Medical records were retrospectively reviewed to obtain information on the severity of LSCD and corrected distance visual acuity (CDVA). LSCD severity was based on a modified severity grading scale. We used an ordered logistic regression model to examine the association between follow-up duration and LSCD severity, and a linear regression model with a generalized linear mixed model for the association between follow-up duration and visual acuity. Results: The mean follow-up duration was 5.2 ± 6.3 years. The mean age at the last follow-up visit was 40.5 ± 18.9 years. The mean CDVA was 1.52 ± 1.09 logMAR. At the last follow-up, 1 examined eye (1.9%) was categorized as stage 0, 7 (13.5%) as Ia, 9 (17.3%) as Ib, 5 (9.6%) as Ic, 2 (3.8%) as IIb, 12 (23.1%) as IIc, and 11 (21.2%) as III. Five eyes (9.6%) were unclassifiable. There was a significant association between follow-up duration and LSCD severity (odds ratio per +1 year, 1.41; P < 0.001). CDVA significantly decreased as follow-up duration increased. Each increase of 1 year in the follow-up duration was associated with a mean difference of +0.021 logMAR (95% confidence interval [CI] 0.01-0.03; P < 0.001). Conclusion: We quantitatively demonstrate that LSCD severity and visual impairment significantly progress as follow-up duration increases.

Association of the CAV1-CAV2 locus with normal-tension glaucoma in Chinese and Japanese.

BACKGROUND: The CAV1-CAV2 locus has been associated with primary open-angle glaucoma (POAG) and intraocular pressure. However, its association with normal-tension glaucoma (NTG) was inconclusive. Therefore, we evaluated this association in Chinese and Japanese. METHODS: Two single-nucleotide polymorphisms (SNPs, rs4236601 and rs1052990) from previous genome-wide association studies of POAG were genotyped in a total of 2220 study subjects: a Hong Kong Chinese cohort of 537 NTG patients and 490 controls, a Shantou Chinese cohort of 102 NTG and 731 controls and an Osaka Japanese cohort of 153 NTG and 207 controls. Subgroup analysis by gender was conducted. Outcomes from different cohorts were combined using meta-analysis. RESULTS: SNP rs4236601 was significantly associated with NTG in the two Chinese cohorts (Pmeta = .0019, OR = 4.55, I2 = 0). In contrast, rs4236601 was monomorphic in the Osaka cohort. The association of rs1052990 was insignificant in a meta-analysis combining Chinese and Japanese cohorts (Pmeta = .81, OR = 1.05; I2 = 64%), and the OR tended towards opposite directions between Chinese (OR = 1.26) and Japanese (OR = 0.69). Gender-specific effects of the SNPs were not statistically significant in the logistic regression or Breslow-day tests of ORs (P > .05), although rs4236601 was significant in males (P = .0068; OR = 10.30) but not in females (P = .14; OR = 2.65) in the meta-analysis of Chinese subjects. CONCLUSIONS: In this study, we confirmed the association of rs4236601 at the CAV1-CAV2 locus with NTG in Chinese. SNP rs4236601 is monomorphic, and rs1052990 tends towards a different direction in the Japanese cohort. Further studies are warranted to verify the ethnic difference and gender-specific effects of this locus.

Efficacy of therapeutic soft contact lens in the management of gelatinous drop-like corneal dystrophy.

BACKGROUND/AIMS: To investigate the efficacy of therapeutic soft contact lenses (SCLs) in gelatinous drop-like corneal dystrophy (GDLD) management. METHODS: This was a retrospective, consecutive, observational case series, including 20 patients (40 eyes) with GDLD treated in Osaka University Hospital within the last 15 years. We tested the effects of therapeutic SCL on clinical features, visual acuity and surgical interventions. Examinations for clinical features and visual acuity were done on patients who had no surgical intervention for 3 years. Scoring and evaluation of changes in three main clinical GDLD features and visual acuity (logMAR units) were performed using Fisher's exact test and Mann-Whitney U test. Surgery-free survival time was compared by Kaplan-Meier analyses in all patients. RESULTS: We found a significantly lower rate of progression in GDLD nodular lesions in patients wearing SCLs compared with those who did not (p=0.0179). No suppressant effects were observed regarding opacity and neovascularisation, and no significant improvements were found in visual acuity (in logMAR values, SCL-on: mean=- 0.036, median=0; SCL-off: mean=0.149, median=+ 0.088; p=0.14). The surgery-free survival time for all 16 SCL-on eyes was 2770 ± 1918 days, significantly longer than that for 22 SCL-off eyes, 1342 ± 1323 days (Kaplan-Meier analysis, p=0.0007), suggesting that therapeutic SCL extends the period until surgical intervention and reduces their necessity in patients with GDLD. CONCLUSION: Wearing therapeutic SCLs in GDLD slows the progression of nodular lesions and decreases the need for surgical interventions.

Correlation Between Angle Parameters and Central Corneal Thickness in Fuchs Endothelial Corneal Dystrophy.

PURPOSE: To evaluate the correlation between anterior chamber parameters and central corneal thickness (CCT) or peripheral corneal thickness (PCT) in patients with Fuchs endothelial corneal dystrophy (FECD) using anterior segment optical coherence tomography. METHODS: This case-control study included 20 eyes from 20 patients with FECD and 31 eyes from 31 patients with healthy corneas. CCT was measured as an indicator of FECD severity. Anterior chamber angle parameters, including trabecular-iris angle (TIA500) and angle opening distance (AOD500), were measured as an indicator of peripheral anterior chamber morphology. We also analyzed PCT and lens vault (LV). The relationships between CCT or PCT and anterior chamber parameters were also analyzed in patients with FECD. RESULTS: Patients with FECD had a larger CCT (593.9 ± 54.6 µm vs. 533.0 ± 25.4 µm, P < 0.001), smaller TIA500 (21.8 ± 9.9 vs. 32.5 ± 11.2 degrees, P = 0.002), smaller AOD500 (0.21 ± 0.11 vs. 0.34 ± 0.18 mm, P = 0.002), and greater LV (0.60 ± 0.27 vs. 0.40 ± 0.29 mm, P = 0.02) than control subjects. In patients with FECD, CCT was negatively correlated with the angle parameters TIA500 (R = 0.29, P = 0.009) and AOD500 (R = 0.19, P = 0.03). There were no significant correlations between PCT and TIA500 (R = 0.008, P = 0.29) or AOD500 (R = 0.007, P = 0.29). There were also no significant correlations between CCT and LV (R = 0.02, P = 0.55). CONCLUSIONS: Larger CCT was significantly associated with narrower anterior chamber angle width, but not with LV. We showed that the severity of FECD is associated with angle chamber morphology.

A novel mutation in gelatinous drop-like corneal dystrophy and functional analysis.

We identified a novel mutation of the tumor-associated calcium signal transducer 2 (TACSTD2) gene in a Japanese patient with gelatinous drop-like corneal dystrophy (GDLD). Genetic analysis revealed a novel homozygous mutation (c.798delG, which may result in frameshift mutation p.Lys267SerfsTer4) in the TACSTD2 gene. This mutated gene was devoid of its original function in helping the claudin (CLDN) 1 and 7 proteins transfer from the cytoplasm to the plasma membrane.

KLF4 prevents epithelial to mesenchymal transition in human corneal epithelial cells via endogenous TGF-ß2 suppression.

INTRODUCTION: Krüppel-like factor 4 (KLF4) is considered one of the Yamanaka factors, and recently, we and others have shown that KLF4 is one of the transcription factors essential for reprogramming non-human corneal epithelial cells (HCECs) into HCECs. Since epithelial to mesenchymal transition (EMT) suppression is vital for homeostasis of HCECs via regulation of transcription factors, in this study, we aimed to investigate whether KLF4 prevents EMT in HCECs and to elucidate the underlying mechanism within the canonical TGF-ß signalling pathway, which is involved in corneal epithelial wound healing. METHODS: HCECs were collected from cadaver donors and cultivated. We generated KLF4-knockdown (KD) HCECs using siRNA transfection and analysed morphology, gene or protein expression, and endogenous TGF-ß secretion. KLF4 was overexpressed using lentiviral KLF4 expression vectors and underwent protein expression analyses after TGF-ß2 treatment. RESULTS: KLF4-KD HCECs showed a fibroblastic morphology, downregulation of the epithelial markers, keratin 12 and keratin 14, and upregulation of the mesenchymal markers, fibronectin 1, vimentin, N-cadherin, and SLUG. Although E-cadherin expression remained unchanged in KLF4-KD HCECs, immunocytochemical analysis showed that E-cadherin-positive adherens junctions decreased in KLF4-KD HCECs as well as the decreased total protein levels of E-cadherin analysed by immunoblotting. Moreover, within the TGF-ß canonical signalling pathway, TGF-ß2 secretion by HCECs increased up to 5 folds, and several TGF-ß-associated markers (TGFB1, TGFB2, TGFBR1, and TGFBR2) were significantly upregulated up to 6 folds in the KLF4-KD HCECs. SMAD2/3, the main signal transduction molecules of the TGF-ß signalling pathway, were found to be localised in the nucleus of KLF4-KD HCECs. When KLF4 was overexpressed, cultivated HCECs showed upregulation of epithelial markers, keratin 14 and E-cadherin, indicating the contributory role of KLF4 in the homeostasis of human corneal epithelium in vivo. In addition, KLF4 overexpression in HCECs resulted in decreased SMAD2 phosphorylation and altered nuclear localisation of SMAD2/3, even after TGF-ß2 treatment. CONCLUSIONS: These results show that KLF4 prevents EMT in HCECs and suggest a novel role of KLF4 as an endogenous TGF-ß2 suppressor in the human corneal epithelium, thus highlighting the potential of KLF4 to prevent EMT and subsequent corneal fibrotic scar formation by attenuating TGF-ß signalling.

Homeostasis of SLC4A11 protein is mediated by endoplasmic reticulum-associated degradation.

The cornea is an important tissue that refracts light, and the corneal endothelium prevents edema of the corneal stroma by acting as a barrier and a pump for the transport of essential molecules/ions. Sodium bicarbonate transporter-like protein 11 (SLC4A11) is a transporter present in the corneal endothelium, and its mutation causes corneal endothelial disease. Here, we aimed to investigate the degradation pathway of SLC4A11. Quantitative PCR analysis revealed that two variants of SLC4A11 transcripts, variant 2 (SLC4A11-B) and variant 3 (SLC4A11-C), were expressed in human corneal endothelial tissues. Transient overexpression of these variants in HEK293T cells revealed that SLC4A11-B abundantly localized to the cell membrane. Furthermore, SLC4A11-B-transfected HEK293T cells expressed the mature glycosylated forms and immature non-glycosylated forms of SLC4A11. Cycloheximide chase experiments revealed that mature SLC4A11 showed high degradation stability; however, degradation of immature SLC4A11-B was significantly faster than that of immature SLC4A11-C. Therefore, we performed further degradation analysis of the SLC4A11 mutants, which are classified into ER-retained and cell surface-associated mutants similar to the wild type. Compared to the wild type, ER-retained mutants S213P and W240P showed delayed degradation but the cell surface-associated mutants showed minimal degradation. Further analysis using proteasome inhibitors revealed that degradation of immature SLC4A11 was delayed after treatment with the proteasome inhibitors, MG-132 and bortezomib, and was mediated by poly-ubiquitination. Moreover, the degradation of immature SLC4A11 protein was suppressed by Eeyarestatin I, an ER-associated protein degradation (ERAD) inhibitor. Collectively, these data suggest that SLC4A11 protein is degraded via ERAD.

Identification and application of p75 neurotrophin receptor-expressing human trabecular meshwork progenitor cells.

The trabecular meshwork (TM) is a tissue that originates from the neural crest via the periocular mesenchyme and plays a role in draining water and maintaining intraocular pressure (IOP). Damage to the TM is associated with pathologically elevated IOP, and cell-based therapy is expected to restore the functions of the TM in the future. Here, we aimed to isolate and characterize TM progenitor cells (TMPs) from human TM tissues. We focused on the p75 neurotrophin receptor (p75), a stem cell marker of the neural crest. Approximately 32% of p75-expressing cells were present in the TM. P75-expressing TMPs could proliferate in serum-free culture. The colony formation efficiency of TMPs was 1.11 ±â€¯0.18%. TMPs showed a markedly lower proliferation ability for passaging. TMPs expressed neural crest markers (p75, Sry-box [SOX] 9, SOX10, transcription factor AP [TFAP] 2B); nestin; periocular mesenchymal markers (Forkhead box [FOX] C1, FOXC2, and paired-like homeodomain transcription factor 2); and CD166, but not TM differentiation markers. The TMPs differentiated into mature TM cells (dTMCs) and keratocytes. dTMCs from TMPs expressed high levels of TM markers (aquaporin 1, matrix gla protein, prostaglandin D2 synthase, and AnkG). Furthermore, the TMPs showed enhanced expression of myocilin, a glaucoma susceptibility gene, following induction of differentiation by dexamethasone. TMPs also differentiated into adipocytes, osteocytes, and chondrocytes. These data suggest that p75-expressing TMPs could be a useful cell source in cell-based therapy and pathological models of glaucoma.

Clinical evaluation of a newly developed graft inserter (NS Endo-Inserter) for Descemet stripping automated endothelial keratoplasty.

PURPOSE: The aim of this study was to describe the postoperative outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) performed using our newly developed graft inserter (NS Endo-Inserter) and compare the findings with those for DSAEK performed using the Busin glide. PATIENTS AND METHODS: In this retrospective, case-control, institutional study, we studied the clinical outcomes of DSAEK performed using the NS Endo-Inserter (NS group, n=13) or the Busin glide (Busin group, n=10) for patients with corneal endothelial dysfunction. Clinical parameters, including the distance-corrected visual acuity (DCVA), endothelial cell (EC) loss, and intraoperative/postoperative complications, were assessed over a 6-month follow-up period. RESULTS: At 6 months after surgery, the mean DCVA showed no significant difference between the two groups. EC loss at 3 and 6 months after DSAEK was 9.1%±20.7% and 18.2%±22.6%, respectively, in the NS group and 44.0%±25.5% and 46.5%±23.3%, respectively, in the Busin group; differences between groups were statistically significant at both 3 and 6 months (P=0.024 and P=0.016, respectively). Anterior chamber hemorrhage was observed in one patient in the Busin group. Rebubbling after surgery was required for one eye in the Busin group. No complications were observed in the NS group. CONCLUSION: Our newly developed graft inserter for DSAEK may cause significantly less EC damage than the conventional pull-through technique using the Busin glide. Our inserter permits safe endothelial graft delivery without anterior chamber collapse and can result in successful graft attachment without complications at 6 months after surgery.

STAT3 signaling maintains homeostasis through a barrier function and cell survival in corneal endothelial cells.

The cornea protects the eye from inflammation, which is one of the leading causes of blindness. Severe inflammation in the anterior chamber disrupts the barrier function of corneal endothelial cells (CECs) leading to severe visual loss. However, the mechanism by which such inflammation affects CEC function and survival is unknown. Activation of STAT3 signaling regulates various intracellular responses through inflammation and generally mediates expression of the barrier function marker zonula occludens-1 (ZO-1). In this study, we investigated the relationship between the corneal endothelial barrier function and activation of STAT3 signaling through a variety of cytokines in human CECs. Phosphorylated STAT3 (pSTAT3) was expressed in human and mouse CECs. Inhibition of pSTAT3 remarkably decreased the expression of the ZO-1 protein, reduced the trans-endothelial electric resistance, and induced cell apoptosis. The expression level of ZO-1 mRNA was correlated with that of STAT3 mRNA in the human corneal endothelium. pSTAT3 was increased with the addition of LIF, IL-6, and IFN-γ. LIF expressed in CECs suppressed pSTAT3 activation as observed experimentally using an anti-LIF antibody. Promoter regions of ZO-1 and SOCS3 were directly regulated by transcriptional activation of STAT3. These findings suggest that regulation of the STAT3 pathway is essential for corneal endothelial homeostasis via barrier function and may protect from various inflammatory factors.