Kojiro Imai

Common variants in CDKN2B-AS1 associated with optic-nerve vulnerability of glaucoma identified by genome-wide association studies in Japanese.

Background To date, only a small portion of the genetic variation for primary open-angle glaucoma (POAG), the major type of glaucoma, has been elucidated. Methods and Principal Findings We examined our two data sets of the genome-wide association studies (GWAS) derived from a total of 2,219 Japanese subjects. First, we performed a GWAS by analyzing 653,519 autosomal common single-nucleotide polymorphisms (SNPs) in 833 POAG patients and 686 controls. As a result, five variants that passed the Bonferroni correction were identified in CDKN2B-AS1 on chromosome 9p21.3, which was already reported to be a significant locus in the Caucasian population. Moreover, we combined the data set with our previous GWAS data set derived from 411 POAG patients and 289 controls by the Mantel-Haenszel test, and all of the combined variants showed stronger association with POAG (P<5.8×10−10). We then subdivided the case groups into two subtypes based on the value of intraocular pressure (IOP)—POAG with high IOP (high pressure glaucoma, HPG) and that with normal IOP (normal pressure glaucoma, NPG)—and performed the GWAS using the two data sets, as the prevalence of NPG in Japanese is much higher than in Caucasians. The results suggested that the variants from the same CDKN2B-AS1 locus were likely to be significant for NPG patients. Conclusions and Significance In this study, we successfully identified POAG-associated variants in the CDKN2B-AS1 locus using a Japanese population, i.e., variants originally reported as being associated with the Caucasian population. Although we cannot rule out that the significance could be due to the differences in sample size between HPG and NPG, the variants could be associated specifically with the vulnerability of the optic nerve to IOP, which is useful for investigating the etiology of glaucoma.

Injection of Cultured Cells with a ROCK Inhibitor for Bullous Keratopathy

BACKGROUND Corneal endothelial cell (CEC) disorders, such as Fuchss endothelial corneal dystrophy, induce abnormal corneal hydration and result in corneal haziness and vision loss known as bullous keratopathy. We investigated whether injection of cultured human CECs supplemented with a rho‐associated protein kinase (ROCK) inhibitor into the anterior chamber could increase CEC density. METHODS We performed an uncontrolled, single‐group study involving 11 persons who had received a diagnosis of bullous keratopathy and had no detectable CECs. Human CECs were cultured from a donor cornea; a total of 1×106 passaged cells were supplemented with a ROCK inhibitor (final volume, 300 μl) and injected into the anterior chamber of the eye that was selected for treatment. After the procedure, patients were placed in a prone position for 3 hours. The primary outcome was restoration of corneal transparency, with a CEC density of more than 500 cells per square millimeter at the central cornea at 24 weeks after cell injection. Secondary outcomes were a corneal thickness of less than 630 μm and an improvement in best corrected visual acuity equivalent to two lines or more on a Landolt C eye chart at 24 weeks after cell injection. RESULTS At 24 weeks after cell injection, we recorded a CEC density of more than 500 cells per square millimeter (range, 947 to 2833) in 11 of the 11 treated eyes (100%; 95% confidence interval [CI], 72 to 100), of which 10 had a CEC density exceeding 1000 cells per square millimeter. A corneal thickness of less than 630 μm (range, 489 to 640) was attained in 10 of the 11 treated eyes (91%; 95% CI, 59 to 100), and an improvement in best corrected visual acuity of two lines or more was recorded in 9 of the 11 treated eyes (82%; 95% CI, 48 to 98). CONCLUSIONS Injection of human CECs supplemented with a ROCK inhibitor was followed by an increase in CEC density after 24 weeks in 11 persons with bullous keratopathy. (Funded by the Japan Agency for Medical Research and Development and others; UMIN number, UMIN000012534.)

Novel common variants and susceptible haplotype for exfoliation glaucoma specific to Asian population

The common variants in lysyl oxidase-like 1 gene (LOXL1) are associated with exfoliation glaucoma (XFG) patients developed through exfoliation syndrome (XFS). However, the risk allele of a variant in LOXL1 has been found to be inverted between Asian and Caucasian populations. Therefore, we newly performed a genome-wide association study using 201 XFS/XFG and 697 controls in Japanese, and identified 34 genome-wide significant single-nucleotide polymorphisms (SNPs) distributing in not only LOXL1 but also TBC1D21 and PML at the 15q24.1 locus. These SNPs were confirmed by an independent population consisted of 121 XFS/XFG and 263 controls in Japanese. Moreover, further analyses revealed a unique haplotype structure only from the combination of TBC1D21 and LOXL1 variants showing a high XFS/XFG susceptibility specific for the Asian population. Although there still should be other gene(s) in the other region(s) contributing to the disease process, these results suggested that the combination of newly discovered variants in these genes might be useful for precise XFG risk assessment, as well as for elucidating the molecular mechanism of XFG pathogenesis through XFS.

Involvement of plasminogen activator inhibitor-1 in the pathogenesis of atopic cataracts.

PURPOSE Further to our previous report of a genetic association between interferon-gamma (IFN-γ) receptor 1 gene and atopic cataract, we investigated the roles of plasminogen activator inhibitor-1 (PAI-1), a fibrosis-related, IFN-γ downstream molecule, in the pathogenesis of atopic cataracts. METHODS Cultured lens epithelial cells (LECs) were stimulated by IFN-γ and quantified by PAI-1 mRNA/protein expression. PAI-1 and TGF-β mRNA expression was quantified using cDNA samples obtained from the lens epithelium of atopic cataract patients (n = 7) and of senile cataract patients (n = 8). The anterior capsules obtained from atopic cataracts (n = 9) were immunostained with anti-PAI-1 and anti-alpha smooth muscle actin (α-SMA) antibodies. PAI-1 gene expression was knocked down by PAI-1 siRNA, and α-SMA expression was examined under TGF-β1 stimulation. Expression of α-SMA was examined as a pathological hallmark of anterior subcapsular cataracts, commonly observed in atopic cataracts. RESULTS The IFN-γ stimulation induced PAI-1 mRNA/protein expression in the LECs from 24 to 48 hours after stimulation. The expression of PAI-1 mRNA and TGF-β1 mRNA was significantly higher in the cDNA samples obtained from the atopic cataracts than those obtained from the senile cataracts. PAI-1-positive immunostaining was observed at the fibrotic lesion of the atopic cataracts, and α-SMA-positive myofibroblasts were observed at the vicinity of the PAI-1-positive lesion in all nine samples examined. PAI-1 gene knockdown resulted in reduced α-SMA expression in the LECs. CONCLUSIONS The findings of this study suggest that the IFN-γ, PAI-1, and TGF-β1 are involved in the pathophysiology of atopic cataracts.

Expression of prostaglandin F receptor in scleral and subconjunctival tissue

Prostaglandin F2α (PGF2α) analogues eye drops are regarded as a first choice for the treatment of glaucoma. The hypotensive action of PGF2α analogues is thought to be attributed to an increase in uveoscleral outflow.1 However, the underlying mechanisms have yet to be well defined. The purpose of this present study was to examine prostaglandin F receptor (FP) localisation in ocular tissue. All experiments were conducted in accordance with the principles set forth in the Declaration of Helsinki. The expression of FP was examined by X-gal staining in ocular tissues of FP knockout mice carrying the β-galactosidase gene at the FP loci ( Ptgfr−/− mice)2 and reverse transcription PCR of human conjuncitival and scleral fibroblasts (see supplementary methods, published online only). First, FP localisation was examined using Ptgfr−/− mice in which the β-galactosidase gene was ‘knocked-in’ at the FP gene. …

Relationship between frequent swimming pool use and lacrimal duct obstruction

Editor, I n our clinical practice, we often encounter frequent swimming pool users and swimming instructors to be among patients with acquired lacrimal duct obstruction (LDO). Only one previous report of 45 patients with primary acquired nasolacrimal duct obstruction has noted that history of swimming pool exposure may be associated with the development of LDO (Ohtomo et al. 2013). To examine whether or not frequent swimming pool use is associated with LDO, we conducted a questionnaire survey of patients who underwent treatment for LDO and compared the results with an ageand gender-matched control group. The questionnaire survey was conducted in 332 patients who visited the Department of Ophthalmology at Kyoto Prefectural University of Medicine, Kyoto, Japan, and underwent surgical treatment (dacryocystorhinostomy or silicone tube insertion) for LDO between April 2003 and March 2009. LDO was defined as the complete obstruction of the nasolacrimal duct, canaliculus or both by syringing and probing during surgery. A questionnaire survey on the frequency of swimming pool use was given to 332 LDO patients, of whom 227 completed the questionnaire (adopted LDO group; 68.4%, 45 males and 182 females, mean age: 65.4 12.8 years), and a control group of 625 patients without LDO (159 males and 466 females, mean age: 63.3 15.3 years), recruited from the outpatient clinic and matched for age and gender. Statistical analysis was performed on the correlation between LDO and frequency of swimming pool use and the frequency between the two groups. Frequent swimming pool use was defined as the use of the pool one or more times per month for a period of at least 6 months. Individuals who had onset of symptoms prior to commencing swimming pool use were not defined as frequent users. Individuals unable to use swimming pools for medical reasons were excluded from the study. The percentage of frequent swimming pool use differed significantly and statistically between the LDO group (35 of 227 patients, 15.4%) and the control group (20 of 625 subjects, 3.2%). In the LDO group, the average age of patients with frequent swimming pool use (60.1 years old) significantly differed from the patients without frequent use (66.4) (Table 1). In the LDO group, patient-age-related percentages of frequent swimming pool use were 100% (2/2, ages 10–19), 20% (1/5, ages 20–29), 0% (0/4, ages 30–39), 40% (4/10, ages 40–49), 18.9% (7/37, ages 50–59), 18.4% (14/76, ages 60–69), 7% (5/71, ages 70–79) and 9% (2/22, ages 80–89). Previous studies have reported epidemiological evidence that bathing or swimming in polluted waters is a potential health risk (Seyfried et al. 1985). In most swimming pools, microbiological control is performed by disinfection via the addition of chlorine. The disinfection properties of free chlorine are linked to its oxidant capacity, and chlorination of swimming pool water leads to the formation of disinfection by-products, including combined chlorine or trihalomethanes, which are associated with some types of illness (Florentin et al. 2011). The phenomenon of a swimming-induced rhinitis in elite swimmers in chlorinated pools has been reported (Alves et al. 2010), and allergic rhinitis may have a role in primary acquired LDO (Eriman et al. 2012). Thus, it is possible that combined chlorine in water is one of the factors potentially involved in LDO among swimming pool users, and our results suggest that frequent swimming pool use may be a risk factor for LDO. Further investigation is needed to provide a more detailed analysis of the relationship between LDO and the quality of swimming pool water.

Impact of high myopia and duration of hard contact lens wear on the progression of ptosis

PurposeTo investigate the impact of myopia and duration of hard contact lens (HCL) wear on the progression of ptosis.MethodsThis study involved 194 eyes of 98 patients with either bilateral or unilateral ptosis with long-term HCL wear. The ptosis of each eyelid was classified into 1 of 4 grades (no ptosis, mild, moderate and severe), and the average spherical equivalent refractive error (SERE), patient age and the duration of HCL wear were then examined.ResultsThe average SERE (in diopters) in 99 severe eyes was −8.34, in 47 moderate eyes, −6.28, in 37 mild eyes −5.57 and in 11 no ptosis eyes, −4.80, while the average duration of HCL wear (in years) were 34, 30, 29, and 31, respectively. The average SERE was significantly higher in the severe than in the moderate, mild and no ptosis eyelids, and the average duration of HCL wear was significantly longer in the severe than in the moderate and mild ptosis eyelids. Path analysis showed that the severity of ptosis is significantly influenced by SERE, as well as by patient age and the duration of HCL wear.ConclusionHigh myopia, patient age and long-term HCL wear are risk factors associated with the progression of ptosis.