Exome-based investigation of the genetic basis of human pigmentary glaucoma.

BACKGROUND: Glaucoma is a leading cause of visual disability and blindness. Release of iris pigment within the eye, pigment dispersion syndrome (PDS), can lead to one type of glaucoma known as pigmentary glaucoma. PDS has a genetic component, however, the genes involved with this condition are largely unknown. We sought to discover genes that cause PDS by testing cohorts of patients and controls for mutations using a tiered analysis of exome data. RESULTS: Our primary analysis evaluated melanosome-related genes that cause dispersion of iris pigment in mice (TYRP1, GPNMB, LYST, DCT, and MITF). We identified rare mutations, but they were not statistically enriched in PDS patients. Our secondary analyses examined PMEL (previously linked with PDS), MRAP, and 19 other genes. Four MRAP mutations were identified in PDS cases but not in controls (p = 0.016). Immunohistochemical analysis of human donor eyes revealed abundant MRAP protein in the iris, the source of pigment in PDS. However, analysis of MRAP in additional cohorts (415 cases and 1645 controls) did not support an association with PDS. We also did not confirm a link between PMEL and PDS in our cohorts due to lack of reported mutations and similar frequency of the variants in PDS patients as in control subjects. CONCLUSIONS: We did not detect a statistical enrichment of mutations in melanosome-related genes in human PDS patients and we found conflicting data about the likely pathogenicity of MRAP mutations. PDS may have a complex genetic basis that is not easily unraveled with exome analyses.

Choriocapillaris Degeneration in Geographic Atrophy.

Early age-related macular degeneration (AMD) is characterized by degeneration of the choriocapillaris, the vascular supply of retinal photoreceptor cells. We assessed vascular loss during disease progression in the choriocapillaris and larger vessels in the deeper choroid. Human donor maculae from controls (n = 99), early AMD (n = 35), or clinically diagnosed with geographic atrophy (GA; n = 9, collected from outside the zone of retinal pigment epithelium degeneration) were evaluated using Ulex europaeus agglutinin-I labeling to discriminate between vessels with intact endothelial cells and ghost vessels. Morphometric analyses of choriocapillaris density (cross-sectional area of capillary lumens divided by length) and of vascular lumen/stroma ratio in the outer choroid were performed. Choriocapillaris loss was observed in early AMD (Bonferroni-corrected P = 0.024) with greater loss in GA (Bonferroni-corrected P < 10-9), even in areas of intact retinal pigment epithelium. In contrast, changes in lumen/stroma ratio in the outer choroid were not found to differ between controls and AMD or GA eyes (P > 0.05), suggesting choriocapillaris changes are more prevalent in AMD than those in the outer choroid. In addition, vascular endothelial growth factor-A levels were negatively correlated with choriocapillaris vascular density. These findings support the concept that choroidal vascular degeneration, predominantly in the microvasculature, contributes to dry AMD progression. Addressing capillary loss in AMD remains an important translational target.

Nanophthalmos patient with a THR518MET mutation in MYRF, a case report.

BACKGROUND: Nanophthalmos has a significant genetic background and disease-causing mutations have been recently been reported in the myelin regulatory factor (MYRF) gene. We report clinical features in a patient with nanophthalmos and a Thr518Met MYRF mutation. CASE PRESENTATION: A three-year-old male was discovered to have nanophthalmos after first presenting to the emergency department for a frontal headache, eye pain, emesis, and lethargy. Imaging studies (CT and MRI) were negative except for increased posterior fossa cerebrospinal fluid. Subsequent examinations revealed nanophthalmos (short axial eye lengths 18.1 mm OD and 18.3 mm OS), microcornea, and a large crystalline lens. Peripheral chorioretinal pigment abnormalities were also observed. He experienced episodes of marked ocular hypertension (53 mmHg OD and 60 mmHg) likely due to intermittent angle closure precipitated by nanophthalmos. The ocular hypertension was responsive to topical medicines. Genetic analysis of known nanophthalmos genes MFRP and TMEM98 were negative, while a novel mutation, Thr518Met was detected in MYRF. The Thr518Met mutation was absent from 362 matched normal controls and was extremely rare in a large population database, allele frequency of 0.000024. The Thr518Met mutation altered a highly conserved amino acid in the MYRF protein and three of four algorithms suggested that this mutation is likely pathogenic. Finally, molecular modeling showed that the Thr518Met mutation is damaging to MYRF structure. Together these data suggest that the Thr518Met mutation causes nanophthalmos. CONCLUSIONS: Nanophthalmos may present at an early age with features of angle closure glaucoma and a Thr518Met mutation in MYRF was detected in a patient with nanophthalmos. Prevalence data, homology data, mutation analysis data, and protein modeling data suggest that this variant is pathogenic and may expand the phenotypic range of syndromic nanophthalmos caused by MYRF mutations to include central nervous system abnormalities (increased posterior fossa cerebrospinal fluid).

OCULAR HYPERTENSION AFTER INTRAVITREAL DEXAMETHASONE (OZURDEX) SUSTAINED-RELEASE IMPLANT.

PURPOSE: To evaluate ocular hypertension (OHT) after Ozurdex injection to determine the incidence of OHT, therapy for OHT, and any associative factors such as diagnosis, underlying glaucoma and therapy, or sequential Ozurdex injection(s). METHODS: Retrospective consecutive case series with patients receiving one or more intravitreal Ozurdex implantations at a tertiary care academic center. Ocular hypertension was defined as a single measurement of ≥30 mmHg or an increase of ≥10 mmHg from baseline. RESULTS: Ninety-four injections in 52 patients (59 eyes) were reviewed. Forty eyes received a single injection, and 19 eyes received multiple injections. Ocular hypertension developed in 14 patients (26.9%). Thirteen patients (25%) had preexisting glaucoma or suspicion of glaucoma, and 6 of these developed OHT. Glaucoma eye drops were initiated after 13 injections (13.8%). Invasive surgery for glaucoma was required in 3 patients (3.2%): all had glaucoma or suspicion of glaucoma (one case was related to neovascular glaucoma and unlikely related to steroid response after Ozurdex). There was no difference in relative intraocular pressure increase (i.e., difference between final follow-up or subsequent intravitreal injection vs. baseline) between single versus multiple Ozurdex injections (P = 0.883). CONCLUSION: Patients (26.9%) who received Ozurdex developed OHT. Glaucoma or glaucoma-suspicion factors were present in all patients who required invasive surgery for glaucoma. A greater proportion of patients who received multiple injections had an intraocular pressure elevation, but the relative intraocular pressure increase was not significant.

Heterozygous triplication of upstream regulatory sequences leads to dysregulation of matrix metalloproteinase 19 in patients with cavitary optic disc anomaly.

Patients with a congenital optic nerve disease, cavitary optic disc anomaly (CODA), are born with profound excavation of the optic nerve resembling glaucoma. We previously mapped the gene that causes autosomal-dominant CODA in a large pedigree to a chromosome 12q locus. Using comparative genomic hybridization and quantitative PCR analysis of this pedigree, we report identifying a 6-Kbp heterozygous triplication upstream of the matrix metalloproteinase 19 (MMP19) gene, present in all 17 affected family members and no normal members. Moreover, the triplication was not detected in 78 control subjects or in the Database of Genomic Variants. We further detected the same 6-Kbp triplication in one of 24 unrelated CODA patients and in none of 172 glaucoma patients. Analysis with a Luciferase assay showed that the 6-Kbp sequence has transcription enhancer activity. A 773-bp fragment of the 6-Kbp DNA segment increased downstream gene expression eightfold, suggesting that triplication of this sequence may lead to dysregulation of the downstream gene, MMP19, in CODA patients. Lastly, immunohistochemical analysis of human donor eyes revealed strong expression of MMP19 in optic nerve head. These data strongly suggest that triplication of an enhancer may lead to overexpression of MMP19 in the optic nerve that causes CODA.

Analysis of ASB10 variants in open angle glaucoma.

Glaucoma is a common cause of visual disability and affects ∼1.6% of individuals over 40 years of age ( 1). Non-synonymous coding sequence variations in the ankyrin repeat and SOCS box containing gene 10 (ASB10) were recently associated with 6.0% of cases of primary open angle glaucoma (POAG) in patients from Oregon and Germany. We tested a cohort of POAG patients (n= 158) and normal control subjects (n= 82), both from Iowa, for ASB10 mutations. Our study had 80% power to detect a 4.9% mutation frequency in POAG patients. A total of 11 non-synonymous coding sequence mutations were detected in the cohort, but no association with POAG was detected when analyzed individually or as a group (P > 0.05). Furthermore, a survey of the National Heart, Lung, and Blood Institute's (NHLBI's) Exome Sequencing Project revealed that non-synonymous ASB10 mutations are present in the general population at a far higher frequency than the prevalence of POAG. These data suggest that non-synonymous mutations in ASB10 do not cause Mendelian forms of POAG.

Copy number variations on chromosome 12q14 in patients with normal tension glaucoma.

We report identification of a novel genetic locus (GLC1P) for normal tension glaucoma (NTG) on chromosome 12q14 using linkage studies of an African-American pedigree (maximum non-parametric linkage score = 19.7, max LOD score = 2.7). Subsequent comparative genomic hybridization and quantitative polymerase chain reaction (PCR) experiments identified a 780 kbp duplication within the GLC1P locus that is co-inherited with NTG in the pedigree. Real-time PCR studies showed that the genes within this duplication [TBK1 (TANK-binding kinase 1), XPOT, RASSF3 and GNS] are all expressed in the human retina. Cohorts of 478 glaucoma patients (including 152 NTG patients), 100 normal control subjects and 400 age-related macular degeneration patients were subsequently tested for copy number variation in GLC1P. Overlapping duplications were detected in 2 (1.3%) of the 152 NTG subjects, one of which had a strong family history of glaucoma. These duplications defined a 300 kbp critical region of GLC1P that spans two genes (TBK1 and XPOT). Microarray expression experiments and northern blot analysis using RNA obtained from human skin fibroblast cells showed that duplication of chromosome 12q14 results in increased TBK1 and GNS transcription. Finally, immunohistochemistry studies showed that TBK1 is expressed in the ganglion cells, nerve fiber layer and microvasculature of the human retina. Together, these data link the duplication of genes on chromosome 12q14 with familial NTG and suggest that an extra copy of the encompassed TBK1 gene is likely responsible for these cases of glaucoma. However, animal studies will be necessary to rule out a role for the other duplicated or neighboring genes.

Thrombospondin Mutations and Patients With Primary Congenital Glaucoma in a United States Population.

Mutations in the thrombospondin 1 ( THBS1 ) gene have been previously reported in primary congenital glaucoma (PCG) pedigrees that exhibit autosomal dominant inheritance with low penetrance. We sought to determine the role of THBS1 mutations in a cohort of 20 patients with PCG and 362 normal controls from Iowa using a combination of Sanger sequencing and whole exome sequencing. We detected 16 different THBS1 variants, including 4 rare, nonsynonymous variants (p.Thr611Met, p.Asn708Lys, p.Gln1089His, and p.Glu1166Lys). However, none of these variants were judged to be disease-causing mutations based on: 1) prevalence in cases and controls from Iowa, 2) prevalence in the public database gnomAD, 3) mutation analysis algorithms, and 4) THBS1 DNA sequence conservation. These results indicate THBS1 mutations are not a common cause of PCG in patients from Iowa and may be a rare cause of PCG overall.

Localization of SH3PXD2B in human eyes and detection of rare variants in patients with anterior segment diseases and glaucoma.

PURPOSE: Analysis of mutant mouse strains and linkage analysis with human families have both demonstrated that mutations influencing the podosomal adaptor protein SH3 and PX domains 2B (SH3PXD2B) can result in a congenital form of glaucoma. Here, we use immunohistochemistry to describe localization of the SH3PXD2B protein throughout the adult human eye and test whether sequence variants in SH3PXD2B occur in multiple other forms of glaucoma. METHODS: In immunohistochemical experiments, cryosections of human donor eyes were evaluated for SH3PXD2B immunoreactivity with a polyclonal antibody. In genetic experiments, exon sequences of SH3PXD2B from patients with primary congenital glaucoma (n=21), Axenfeld-Rieger syndrome (n=30), and primary open angle glaucoma (n=127) were compared to control subjects (n=89). The frequency of non-synonymous SH3PXD2B coding sequence variants were compared between patient cohorts and controls using Fisher's exact test. RESULTS: Varying intensities of SH3PXD2B immunoreactivity were detected in almost all ocular tissues. Among tissues important to glaucoma, immunoreactivity was detected in the drainage structures of the iridocorneal angle, ciliary body, and retinal ganglion cells. Intense immunoreactivity was present in photoreceptor inner segments. From DNA analysis, a total of 11 non-synonymous variants were detected. By Fisher's Exact test, there was not a significant skew in the overall frequency of these changes in any patient cohort versus controls (p-value >0.05). Each cohort contained unique variants not detected in other cohorts or patients. CONCLUSIONS: SH3PXD2B is widely distributed in the adult human eye, including several tissues important to glaucoma pathogenesis. Analysis of DNA variants in three forms of glaucoma detected multiple variants unique to each patient cohort. While statistical analysis failed to support a pathogenic role for these variants, some of them may be rare disease-causing variants whose biologic significance warrants investigation in follow up replication studies and functional assays.

Glaucoma therapy escalation in eyes with pseudophakic corneal edema after penetrating keratoplasty and Descemet's stripping automated endothelial keratoplasty.

The purpose of this study was to determine and compare the prevalence of glaucoma therapy escalation (GTE) after penetrating keratoplasty (PKP) and Descemet's stripping automated endothelial keratoplasty (DSAEK) in eyes with a surgical indication of pseudophakic corneal edema. A retrospective review was conducted of the medical records of all patients who underwent PKP or DSAEK to treat pseudophakic corneal edema at a tertiary eye care center from January 1 2003 to December 31, 2006. Eyes that were treated with PKP from January 1, 2003 to December 31, 2004 and with DSAEK from January 1, 2005 to December 31, 2006 were included in the statistical analysis. Inclusion criteria included satisfactory preoperative control of intraocular pressure (IOP) and follow-up of at least 12 months. The main outcome measure was GTE, which was defined as a sustained requirement for escalation of topical medical therapy or the need to provide surgical intervention to maintain a satisfactory postoperative IOP. Among 54 eyes that met the inclusion criteria, GTE occurred in 7 (35.0%) of 20 eyes after PKP and in 14 (41.2%) of 34 eyes after DSAEK (P = 0.78) during a mean follow-up period of 27.6 and 28.6 months, respectively. Surgical escalation occurred in 2 (10.0%) eyes after PKP and 2 (5.9%) eyes after DSAEK (P = 0.62), and was associated with late-onset endothelial graft failure in all four eyes. Glaucoma therapy escalation is relatively common and occurs with comparable frequency in eyes with pseudophakic corneal edema after PKP and DSAEK.

Genome-wide analysis of copy number variants in age-related macular degeneration.

Age-related macular degeneration (AMD) is a complex genetic disease, with many loci demonstrating appreciable attributable disease risk. Despite significant progress toward understanding the genetic and environmental etiology of AMD, identification of additional risk factors is necessary to fully appreciate and treat AMD pathology. In this study, we investigated copy number variants (CNVs) as potential AMD risk variants in a cohort of 400 AMD patients and 500 AMD-free controls ascertained at the University of Iowa. We used three publicly available copy number programs to analyze signal intensity data from Affymetrix GeneChip SNP Microarrays. CNVs were ranked based on prevalence in the disease cohort and absence from the control group; high interest CNVs were subsequently confirmed by qPCR. While we did not observe a single-locus "risk CNV" that could account for a major fraction of AMD, we identified several rare and overlapping CNVs containing or flanking compelling candidate genes such as NPHP1 and EFEMP1. These and other candidate genes highlighted by this study deserve further scrutiny as sources of genetic risk for AMD.

Chromosome 7q31 POAG locus: ocular expression of caveolins and lack of association with POAG in a US cohort.

PURPOSE: To determine the role of the recently discovered primary open angle glaucoma (POAG) risk factor mapped to chromosome 7q31 in glaucoma patients from Iowa and to determine the expression pattern of genes in the locus in human eyes. METHODS: A cohort of 545 POAG patients and 297 control subjects from Iowa were genotyped with a single nucleotide polymorphism (SNP; rs4236601) in the chromosome 7q31 locus using a quantitative polymerase chain reaction (PCR) assay. The expression of genes within the 7q31 locus, caveolin-1 (CAV1) and caveolin-2 (CAV2) in human eyes was investigated with immunohistochemistry. RESULTS: The minor allele frequency (MAF) of rs4236601 was 27% in control subjects and 29% in POAG patients. We detected no statistical difference when we compared the allele frequencies of rs4236601 between POAG patients and control subjects (p=0.5). Similarly, we detected no statistical difference in the frequency of the three possible rs4236601 genotypes between patients and controls (p=0.22). Immunohistochemistry showed caveolin expression in human retina, ciliary muscle, trabecular meshwork, and Schlemm's canal. In our small cohort of donor eyes, the genotype of rs4236601 did not obviously influence labeling intensity or distribution of CAV1 and CAV2 in the retina. CONCLUSIONS: A genome-wide association study of subjects from Iceland mapped the first common genetic risk factor for POAG to a small region of the genome on chromosome 7q31 that contains the caveolin genes CAV1 and CAV2. We were unable to detect this association in our patients from Iowa, suggesting that this risk factor may not have a strong effect in all populations.

Vision loss after inadvertent corneal perforation during lid anesthesia.

A 68-year-old woman was referred for glaucoma management after inadvertent corneal perforation during eyelid anesthesia for upper eyelid blepharoplasty. A mixture of 50:50 2% lidocaine with 1:100,000 epinephrine and 0.5% bupivacaine buffered with sodium bicarbonate was injected intracamerally. Decreased vision and uncontrollable intraocular pressure resulted, despite prompt anterior chamber washout. Examination showed corneal edema, inflammation, and secondary angle closure. Intraocular pressure control with seton placement led to an improvement in vision; however, mild corneal haze remained, and specular microscopy showed endothelial cell loss, presumably secondary to local anesthetic toxicity. Inadvertent ocular penetration is a rare but serious complication of local eyelid anesthesia. Prompt recognition is essential to institute appropriate management and minimize subsequent vision loss.

Exogenous modulation of intrinsic optic nerve neuroprotective activity.

BACKGROUND: To characterize the molecular and functional status of the rat retina and optic nerve after acute elevation of intraocular pressure (IOP). METHODS: Retinal ischemia was induced in rats by increasing the IOP (110 mmHg/60 minutes). Microarray analysis, quantitative RT-PCR (qRT-PCR) and immunohistochemistry were used to characterize retinal tissue. PLGA microspheres containing neurotrophic factors (BDNF, GDNF, or CNTF) or empty microspheres were injected into the vitreous of operated animals 1 day after elevation of IOP. Pupil light reflex (PLR) parameters and electroretinograms (ERG) were monitored at multiple time points during the 60-day postoperative recovery period. RESULTS: Molecular analysis showed a significant intrinsic up-regulation of CNTF at 10 and 25 days after induction of the acute ocular hypertension (p = 0.0067). Molecular tissue analysis of GDNF and its receptors (GDNFR1, GDNFR2), and BDNF and its receptor (trkB) showed no change in expression. Animals that received CNTF microspheres had no significant functional recovery compared to animals which received blank microspheres (p > 0.05). Animals that received GDNF or BDNF microspheres showed significant PLR recovery (p < 0.05 and p < 0.001 respectively) compared to non-treated animals. CONCLUSIONS: Continuous release of neurotrophic growth factors (NGFs) significantly protects optic nerve function in the experimental model of retinal ischemia observed by PLR analysis.

The Heritability of Pigment Dispersion Syndrome and Pigmentary Glaucoma.

PURPOSE: Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are presumed to be inherited in an autosomal dominant manner. We examine relatives of patients with PDS and PG in order to determine the heritability of these diseases. DESIGN: This was a prospective, cross-sectional study. METHODS: One hundred and one patients with PDS were prospectively recruited over 11 months. Four of the patients had PDS without ocular hypertension or glaucoma, 6 had PDS and ocular hypertension, and 91 had PG. Criteria for PDS were 2 of 3 signs: Krukenberg spindle, midperipheral iris transillumination defects, and/or heavy trabecular meshwork pigmentation. Criteria for PG were PDS and 2 of 3 signs: intraocular pressure >21 mm Hg, glaucomatous optic nerve damage, and/or glaucomatous visual field loss. Ninety-nine first-degree relatives living within a 100-mile radius of Iowa City, Iowa were examined in the clinic to determine the probability of familial transmission. RESULTS: A total of 10 of 99 (10.10%) first-degree relatives were diagnosed with PDS (1 with PDS alone, 2 with PDS and ocular hypertension, and 7 with PG). Seven families with ≥2 affected members were identified. The majority of affected family members (8/10) showed moderate to heavy trabecular meshwork pigmentation and either Krukenberg spindle or transillumination defects. CONCLUSIONS: Most of the cases of PDS in our study were sporadic, and the risk to first-degree relatives is lower than previously reported. However, there are families with apparent autosomal dominant inheritance of PDS in which the risk to relatives may be high.

Room-Temperature Ferromagnetic Ultrathin α-MoO3:Te Nanoflakes.

We materialized room-temperature ferromagnetism in ultrathin α-MoO3:Te nanoflakes. The α-MoO3:Te nanoflakes, which had been grown by vapor-phase epitaxy, clearly exhibited an Ag Raman band from symmetric stretching of υ(Mo-O3-Mo) in the 2D-like ultrathin α-MoO3:Te layer. Due to the intentional incorporation of smaller Te ions into bigger Mo sites, the pentacoordinated Mo5+ bonds were created inside the orthorhombic α-MoO3:Te lattice system. Since Mo5+ ions have magnetic moments from unpaired electron spins, a large number of overlapped bound magnetic polarons could be formed via ferromagnetic coupling with charged oxygen vacancies that are inevitably generated at pentacoordinated [Mo5+O5] centers. This gives rise to the increase in long-range ferromagnetic ordering and leads to room-temperature ferromagnetism in the entire α-MoO3:Te solid-state system. The results may move a step closer to the demonstration of spin functionalities in the wide bandgap semiconductor α-MoO3:Te.

Myocilin Mutations in Patients With Normal-Tension Glaucoma.

Importance: Mutations in the myocilin (MYOC) gene are the most common molecularly defined cause of primary open-angle glaucoma that typically occurs in patients with high intraocular pressures (IOP). One MYOC mutation, p.Gln368Ter, has been associated with as many as 1.6% of primary open-angle glaucoma cases that had a mean maximum recorded IOP of 30 mm Hg. However, to our knowledge, the role of the p.Gln368Ter mutation in patients with normal-tension glaucoma (NTG) with an IOP of 21 mm Hg or lower has not been investigated. Objective: To evaluate the role of the p.Gln368Ter MYOC mutation in patients with NTG. Design, Setting, and Participants: In this case-control study of the prevalence of the p.Gln368Ter mutation in patients with NTG, cohort 1 was composed of 772 patients with NTG and 2152 controls from the United States (Iowa, Minnesota, and New York) and England and cohort 2 was composed of 561 patients with NTG and 2606 controls from the Massachusetts Eye and Ear Infirmary and the NEIGHBORHOOD consortium. Genotyping was conducted using real-time polymerase chain reaction that was confirmed with Sanger sequencing, the imputation of genome-wide association study data, or an analysis of whole-exome sequence data. Data analysis occurred between April 2007 and April 2018. Main Outcomes and Measures: Comparison of the frequency of the p.Gln368Ter MYOC mutation between NTG cases and controls with the Fisher exact test. Results: Of 6091 total participants, 3346 (54.9%) were women and 5799 (95.2%) were white. We detected the p.Gln368Ter mutation in 7 of 772 patients with NTG (0.91%) and 7 of 2152 controls (0.33%) in cohort 1 (P = .03). In cohort 2, we detected the p.Gln368Ter mutation in 4 of 561 patients with NTG (0.71%) and 10 of 2606 controls (0.38%; P = .15). When the cohorts were analyzed as a group, the p.Gln368Ter mutation was associated with NTG (odds ratio, 2.3; 95% CI, 0.98-5.3; P = .04). Conclusions and Relevance: In cohorts 1 and 2, the p.Gln368Ter mutation in MYOC was found in patients with IOPs that were 21 mm Hg or lower (NTG), although at a frequency that is lower than previously detected in patients with higher IOP. These data suggest that the p.Gln368Ter mutation may be associated with glaucoma in patients with normal IOPs as well as in patients with IOPs that are greater than 21 mm Hg.

Neuroglobin and cytoglobin distribution in the anterior eye segment: a comparative immunohistochemical study.

This study provides a detailed description of immunolocalization of two oxygen-binding proteins, neuroglobin (Ngb) and cytoglobin (Cygb), in the anterior segment of healthy human and canine eyes. Specific antibodies against Ngb and Cygb were used to examine their distribution patterns in anterior segment structures including the cornea, iris, trabecular meshwork, canal of Schlemm, ciliary body, and lens. Patterns of immunoreactivity (IR) were imaged with confocal scanning laser and conventional microscopy. Analysis of sectioned human and canine eyes showed Ngb and Cygb IR in the corneal epithelium and endothelium. In the iris, Ngb and Cygb IR was localized to the anterior border and the stroma, iridal sphincter, and dilator muscle. In the iridocorneal angle, Ngb and Cygb were detected in endothelial cells of the trabecular meshwork and canal of Schlemm in human. In the ciliary body, Ngb and Cygb IR was localized to the non-pigmented ciliary epithelium of the pars plana and pars plicata and in ciliary body musculature. Ngb and Cygb distribution was similar and colocalized within the same structures of healthy human and canine anterior eye segments. Based on their immunolocalization and previously reported biochemical features, we hypothesize that Ngb and Cygb may function as scavengers of reactive oxygen species. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Disruption of the complement cascade delays retinal ganglion cell death following retinal ischemia-reperfusion.

Recent reports have indicated that components of the complement cascade are synthesized during the degeneration of retinal ganglion cells (RGC) in glaucoma. While complement deposition in the retina may simply serve to aid phagocytosis of damaged RGC, activation of the complement cascade can also contribute to neuronal loss in neurodegenerative diseases. This study was designed to determine if disruption of the complement cascade affects RGC survival in a murine model of retinal ischemia-reperfusion (I/R) injury. We induced retinal ischemia in the eyes of normal mice and mice with a targeted disruption of the complement component 3 (C3) gene. Tissue was harvested 7 and 21 days after induction of I/R and retinal complement synthesis was determined by quantitative PCR and immunohistochemical methods. RGC death and associated axon loss was evaluated through histological examination of the optic nerve and retina. Our data show that retinal I/R induces the expression and deposition of complement components. C3 deficient mice clearly exhibited reduced optic nerve damage and substantial preservation of RGC 1 week after I/R when compared to normal animals (p=0.005). Three weeks after the ischemic event C3 deficient mice retained more RGC cell bodies although the degree of optic nerve damage was similar between both groups. These findings demonstrate that inhibition of the complement cascade delays optic nerve axonal and RGC degeneration in retinal I/R. It appears that injured RGC are targeted and actively destroyed through complement mediated processes. These results may have implications for the pathophysiology and clinical management of ischemic retinal conditions.