http://repub.eur.nl/res/aut/4714/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/26304/ 2011-06-01T00:00:00Z Background/aims: The neonatal Fc receptor (FcRn) protects immunoglobulin G (IgG) from catabolism, controls its transport between cell layers and extends its serum half-life. In the human, vitreous IgG can be found, but how vitreous IgG is processed or transported is currently unknown. The FcRn is a candidate molecule to regulate these processes. The authors examined FcRn expression and regulation in human retinal pigment epithelium (RPE) cells. Methods: In three primary RPE cell cultures (from three donor eyes) and in the human RPE cell line ARPE-19, FcRn and beta-2-microglobulin (β2M) mRNA levels were determined by real-time quantitative PCR. FcRn protein expression was analysed by western blot studies. Stimulation experiments were performed with recombinant human tumour necrosis factor (TNF)-α and interferon (IFN)-γ. HT-29, THP-1 and HeLa cell lines were used as FcRn positive and negative non-ocular controls, respectively. Results: Expression of FcRn mRNA and protein was demonstrated in all three RPE cultures. After stimulation with TNF-α, FcRn expression is downregulated in RPE cells and upregulated in HT-29 and THP-1 cells. IFN-γ has no effect on FcRn expression in RPE cells. Conclusions: Human RPE cells express FcRn. The proinflammatory cytokine TNF-α downregulates FcRn expression. The authors speculate that the FcRn may play a pivotal role in the immune privilege of the human eye. http://repub.eur.nl/res/pub/22855/ 2011-05-01T00:00:00Z Background and aims: Biologicals and small inhibitory molecules are used to treat inflammatory diseases, but their efficacy varies upon clinical application. Using a whole orbital tissue culture system, we tested the potential efficacy of imatinib mesylate (a tyrosine kinase inhibitor that blocks platelet-derived growth factor (PDGF)-receptor, c-Abl and c-Kit activity) and adalimumab (an anti-TNF-α antibody) for the treatment of Graves' ophthalmopathy (GO). Methods: Orbital fat tissue from GO patients (n=10) was cultured with or without imatinib mesylate or adalimumab. PDGF-B and tumour necrosis factor (TNF)-α mRNA expression levels were determined in the primary orbital tissue, and interleukin (IL)-6 and hyaluronan were measured in tissue-culture supernatants. Results: Imatinib mesylate significantly (p=0.005) reduced IL-6 and hyaluronan production. The inhibition of hyaluronan production correlated positively and significantly (p<0.05) with the PDGF-B mRNA level in the primary tissue. Adalimumab also significantly (p=0.005) reduced IL-6 production. The amount of IL-6 inhibition correlated positively with the TNF-α mRNA level in the primary tissue, but this was not significant. Conclusions: Imatinib mesylate can be expected to reduce inflammation and tissue remodelling in GO, while adalimumab can be mainly expected to reduce inflammation. This in vitro tissue-culture model may, in future, prove valuable to test novel therapeutics for their presumed effect in GO as well as in other inflammatory diseases. http://repub.eur.nl/res/pub/27716/ 2010-11-01T00:00:00Z PURPOSE. Achromatopsia (ACHM) is a congenital autosomal recessive cone disorder with a presumed stationary nature and only a few causative genes. Animal studies suggest that ACHM may be a good candidate for corrective gene therapy. Future implementation of this therapy in humans requires the presence of viable cone cells in the retina. In this study the presence of cone cells in ACHM was determined, as a function of age. METHODS. The appearance and thickness of all retinal layers were evaluated by spectral-domain optical coherence tomography (SD-OCT) in 40 ACHM patients (age range, 4-70 years) with known mutations in the CNGB3, CNGA3, and PDE6C genes. A comparison was made with 55 healthy age-matched control subjects. RESULTS. The initial feature of cone cell decay was loss of inner and outer segments with disruption of the ciliary layer on OCT, which was observed as early as 8 years of age. Cone cell loss further progressed with age and occurred in 8 (42%) of 19 patients below 30 years and in 20 (95%) of 21 of those aged 30+ years. Retinal thickness was significantly thinner in the fovea of all patients (126 μm in ACHM vs. 225 μm in the control; P < 0.001) and correlated with age (β = 0.065; P = 0.011). Foveal hypoplasia was present in 24 (80%) of 30 patients and in 1 of 55 control subjects. CONCLUSIONS. ACHM is not a stationary disease. The first signs of cone cell loss occur in early childhood. If intervention becomes available in the future, the present results imply that it should be applied in the first decade. http://repub.eur.nl/res/pub/20895/ 2010-09-01T00:00:00Z Refractive errors are the most common ocular disorders worldwide and may lead to blindness. Although this trait is highly heritable, identification of susceptibility genes has been challenging. We conducted a genome-wide association study for refractive error in 5,328 individuals from a Dutch population-based study with replication in four independent cohorts (combined 10,280 individuals in the replication stage). We identified a significant association at chromosome 15q14 (rs634990, P = 2.21 × 10−14). The odds ratio of myopia compared to hyperopia for the minor allele (minor allele frequency = 0.47) was 1.41 (95% CI 1.16–1.70) for individuals heterozygous for the allele and 1.83 (95% CI 1.42–2.36) for individuals homozygous for the allele. The associated locus is near two genes that are expressed in the retina, GJD2 and ACTC1, and appears to harbor regulatory elements which may influence transcription of these genes. Our data suggest that common variants at 15q14 influence susceptibility for refractive errors in the general population. http://repub.eur.nl/res/pub/20901/ 2010-09-01T00:00:00Z Refractive errors are the most common ocular disorders worldwide and may lead to blindness. Although this trait is highly heritable, identification of susceptibility genes has been challenging. We conducted a genome-wide association study for refractive error in 5,328 individuals from a Dutch population-based study with replication in four independent cohorts (combined 10,280 individuals in the replication stage). We identified a significant association at chromosome 15q14 (rs634990, P = 2.21 × 10−14). The odds ratio of myopia compared to hyperopia for the minor allele (minor allele frequency = 0.47) was 1.41 (95% CI 1.16–1.70) for individuals heterozygous for the allele and 1.83 (95% CI 1.42–2.36) for individuals homozygous for the allele. The associated locus is near two genes that are expressed in the retina, GJD2 and ACTC1, and appears to harbor regulatory elements which may influence transcription of these genes. Our data suggest that common variants at 15q14 influence susceptibility for refractive errors in the general population. http://repub.eur.nl/res/pub/19308/ 2010-01-01T00:00:00Z PURPOSE: Graves' ophthalmopathy (GO) is characterized by the infiltration of immune cells into the orbit, a process in which cytokines play a central role. Orbital fibroblasts are potent producers of cytokines on different stimuli. Recently, the authors showed increased expression of the PDGF-B chain in GO orbital tissue. The dimeric PDGF-BB molecule has been described to activate the NF-kappaB pathway, which is well recognized for its role in regulating cytokine production. This study was conducted to determine the role of PDGF-BB in the production of proinflammatory cytokines by orbital fibroblasts in GO. METHODS: Orbital, lung, and skin fibroblasts were stimulated with PDGF-BB, and cytokine (IL-1beta, IL-6, IL-8, IL-16, CCL2, CCL5, CCL7, TNF-alpha) production was measured by ELISA. Involvement of NF-kappaB activation through PDGF signaling was investigated by electrophoretic mobility shift assay, specific NF-kappaB inhibitors, and the PDGF-receptor kinase inhibitor imatinib mesylate. RESULTS: IL-6, IL-8, CCL2, CCL5, and CCL7 production by orbital fibroblasts was increased by PDGF-BB stimulation, whereas IL-16, IL-1beta, and TNF-alpha production was not affected. PDGF-BB induced NF-kappaB activity in orbital fibroblasts, and both NF-kappaB inhibitors and imatinib mesylate reduced PDGF-BB-induced cytokine production. Similar, but less vigorous, effects of PDGF-BB on cytokine production were observed in lung and skin fibroblasts. CONCLUSIONS: PDGF-BB is a potent inducer of proinflammatory cytokines via the NF-kappaB pathway in orbital fibroblasts, whereas cytokine production by fibroblasts from other anatomic locations showed a moderate response. These data suggest a possible role for PDGF-BB in regulating orbital inflammation in GO and identify the PDGF signaling cascade as a therapeutic target in GO. http://repub.eur.nl/res/pub/25298/ 2009-02-01T00:00:00Z PURPOSE. Varicella zoster virus (VZV)-induced retinitis is characterized by the presence of virus-infected cells in the retinal layer and the ocular infiltration of VZV-specific T cells. Herein, the susceptibility of human retinal pigment epithelial (RPE) cells to VZV infection and the ability of virus-specific CD4+T cells to control VZV infection in RPE cells in vitro is addressed. METHODS. Human primary RPE cell cultures (n = 2) were infected with a VZV strain expressing green fluorescent protein. The infection and viability of infected RPE cells was monitored by flow cytometry or by a fluorescent imager on RPE monolayers. RPE cells, pretreated with or without interferon-γ (IFN-γ), were infected with VZV and subsequently cultured with VZV-specific CD4+T-cell clones (TCCs; n = 3) recognizing disparate VZV proteins presented by different HLA class II alleles. IFN-γ production and cytotoxicity of the TCCs in response to VZV-infected RPE cells was determined by flow cytometry. RESULTS. Human RPE cells are permissive to a productive VZV infection. VZV-infected RPE cells presented the cognate antigen to the CD4+TCCs only if the RPE cells were pretreated with IFN-γ and expressed the appropriate HLA class II allele. VZV-specific TCCs inhibited productive VZV infection in RPE cells, which was in part attributed to TCC-mediated killing of the VZV-infected RPE cells. CONCLUSIONS. The results presented suggest that RPE cells may play a role as retina-resident antigen-presenting cells in the intraocular, VZV-specific, T cell-mediated inflammatory response of VZV-induced uveitis. http://repub.eur.nl/res/pub/35089/ 2007-12-01T00:00:00Z Purpose: To report on the efficacy of the somatostatin analog octreotide long-acting repeatable (LAR), in the treatment of uveitic chronic macular edema (CME). Design: Case series, retrospective analysis. Methods: In 20 patients, 20 episodes of recurrent CME during otherwise quiescent uveitis were treated with intramuscular octreotide LAR injections. Patients were included if CME control with acetazolamide or systemic and periocular steroids had failed during previous CME episodes or if contraindications existed for persistent use of these therapies. Mean outcome points were CME and visual acuity changes. Correlation of prognostic factors with these outcomes was analyzed. Results: The included CME episodes occurred 7.6 ± 1.4 years after onset of uveitis. Octreotide LAR treatment started 7.0 ± 7.3 months after diagnosis of CME. CME decreased in 70% of episodes, after 2.7 ± 1.3 months of treatment. After arrest of successful treatment, CME recurred instantly (27.2%) or within six months (36.4%). In 36.4% of successfully treated episodes, CME was absent for more than one year. A probable prognostic factor for success was the duration of CME before treatment. Conclusions: Octreotide LAR had an edema-reducing effect in 70% of treated CME episodes. Successful response was related to duration of CME before start of treatment. The early recurrence of CME (63.6%) after arrest of octreotide LAR advocates a long-term treatment in recent episodes of macular edema in otherwise quiescent uveitis. http://repub.eur.nl/res/pub/35758/ 2007-08-01T00:00:00Z PURPOSE. Varicella zoster virus (VZV) is a common cause of infectious uveitis associated with an intraocular inflammatory response involving virus-specific T cells. In the current study, the functional characteristics and the antigen specificity of VZV-reactive T cells recovered from intraocular fluid (IOF) samples of five patients with VZV were determined. METHODS. B-cell lines were infected with a comprehensive panel of recombinant vaccinia viruses expressing 11 individual VZV open reading frames (ORFs), or alternatively pulsed with the corresponding peptides to generate antigen-presenting cells (APCs). T-cell responsiveness of the IOF-derived VZV-specific T cells toward APCs was monitored by interferon (IFN)-γ enzyme-linked immunosorbent spot-forming assays on bulk T-cell cultures and subsequently T-cell clones (TCCs). The cytokine-secretion profile and cytotoxicity of the VZV-specific TCCs was determined by ELISA and flow cytometry, respectively. RESULTS. T-cell reactivity to VZV proteins encoded by ORF4, -10, -14, -18, -29, -31, -61, -62, -63, -67, and -68 was demonstrated, but specificity varied individually. T-cell epitopes on ORF62 and -68 were delineated. The TCCs secreted IFNγ, but relatively low levels of interleukin-4 and -5, in response to VZV antigen-expressing APCs. The TCCs induced antigen-specific cytotoxic T-cell activity. CONCLUSIONS. The results suggest that the intraocular VZV-specific T-cell response in the patients with VZV analyzed is directed to a broad spectrum of VZV antigens, including the latency-associated VZV proteins from ORFs 4, 29, 63, and particularly ORF62. This local T-cell response was in part mediated by cytotoxic CD4+T cells with a Th1/0-like effector memory phenotype. Copyright http://repub.eur.nl/res/pub/13782/ 2005-05-01T00:00:00Z AIM: To describe the effect of additional treatment with anti-TNF-alpha therapy in a case series of 13 patients with serious sight threatening uveitis. METHODS: 13 patients with serious sight threatening uveitis were included, of whom six had Behcet's disease, five had idiopathic posterior uveitis, one had sarcoidosis, and one birdshot retinochoroiditis. Onset and course of ocular inflammation, inflammatory signs, and visual acuity were assessed. Patients were treated with 200 mg (approximately 3 mg/kg) infliximab infusion. Repeat infusions were given based on clinical response. RESULTS: Infliximab treatment resulted in an effective suppression of ocular inflammation in all patients. In patients with non-Behcet's disease uveitis visual acuity in six out of eight improved or was stable. In patients with Behcet's disease visual acuity in five out of six improved or was stable. CONCLUSION: Anti-TNF-alpha treatment may be of value in the treatment of uveitis, and in patients with Behcet's disease, leading to suppression of ocular inflammation, vasculitis, and improvement of vision in the majority. Based on these results a controlled masked study is warranted. http://repub.eur.nl/res/pub/10278/ 2004-01-01T00:00:00Z AIM: To evaluate the possibility of translocating autologous peripheral retinal pigment epithelial (RPE) cells and enhance their adhesion to improve functional outcome after choroidal neovascular membrane extraction in patients with subfoveal neovascular membranes. METHODS: A prospective, non-controlled surgical study in eight consecutive patients operated between February and July 2001 with final data monitoring in July 2002. All patients had mixed subfoveal membranes of 2-4 disc diameters. Functional tests included Snellen vision and central fixation testing. During vitrectomy, after the extraction of the neovascular complex, 8 x 10(4)-16 x 10(4) RPE cells were removed from the periphery and translocated under the macula following the submacular injection of 2 microg of poly-L-lysine to promote adhesion of the cells. RESULTS: With a follow up ranging from 3 months to 16 months, a pigmented area was seen in the extraction bed of the neovascular membrane in only one patient. Fixation was at the edge of the extraction bed in three patients. Vision remained the same in five patients and deteriorated in three (all with retinal detachment). Retinal detachment due to proliferative vitreoretinopathy occurred in three patients. CONCLUSIONS: The translocation of autologous peripheral RPE cells after membrane extraction was technically possible in a sterile manner, but was associated with a high proliferative vitreoretinopathy rate and in the present series had no measurable positive effect on functional outcome. http://repub.eur.nl/res/pub/10127/ 2003-01-01T00:00:00Z PURPOSE: The insulin-like growth factor (IGF)-I protein is a growth-promoting polypeptide that can act as an angiogenic agent in the eye. The purpose of the current study was to localize the expression of IGF-I and its receptor (IGF-IR) mRNA and IGF-IR protein in situ in the normal human eye and to examine the presence of expression in eyes with neovascular age-related macular degeneration (AMD). METHODS: Formalin-fixed, paraffin-embedded slides of 4 normal control eyes and 14 eyes with choroidal neovascularization (CNV) secondary to AMD were examined. Three eyes with proliferative diabetic retinopathy were studied as the positive control. IGF-I and IGF-IR mRNA was detected by in situ hybridization with digoxigenin-labeled RNA probes. IGF-IR protein was studied by immunohistochemistry. RESULTS: In the normal retina, IGF-I and IGF-IR mRNA expression was found throughout the neuroretinal layers, in the retinal pigment epithelium (RPE), and in some choriocapillary and retinal capillary endothelial cells. In eyes with CNV we found IGF and IGF-IR mRNA in capillary endothelial cells, some transdifferentiated RPE, and fibroblast-like cells. IGF-IR protein was found in normal eyes in all neuroretinal layers, in the RPE, and in the choroidal vessels. In eyes with CNV, IGF-IR protein was present in the RPE monolayer, in transdifferentiated RPE, and in newly formed vessels. CONCLUSIONS: The colocalization of protein and receptor indicates an autocrine function of IGF-I in the normal human retina. Because IGF-I participates in ocular neovascularization, synthesis of IGF-IR and IGF-I in endothelial cells, RPE cells, and fibroblast-like cells in CNV may point toward a role for this growth factor in the pathogenesis of neovascular AMD. http://repub.eur.nl/res/pub/9421/ 2000-01-01T00:00:00Z PURPOSE: The growth of ocular neovascularization is regulated by a balance between stimulating and inhibiting growth factors. Somatostatin affects angiogenesis by inhibiting the growth hormone-insulin-like growth factor axis and also has a direct antiproliferative effect on human retinal endothelial cells. The purpose of our study is to investigate the expression of somatostatin receptor (sst) subtypes and particularly sst subtype 2A (sst2A) in normal human macula, and to study sst2A in different stages of age-related maculopathy (ARM), because of the potential anti-angiogenic effect of somatostatin analogues. METHODS: Sixteen eyes (10 enucleated eyes, 4 donor eyes, and 2 surgically removed choroidal neovascular [CNV] membranes) of 15 patients with eyes at different stages of ARM were used for immunohistochemistry. Formaldehyde-fixed paraffin-embedded slides were incubated with a polyclonal anti-human sst2A antibody. mRNA expression of five ssts and somatostatin was determined in the posterior pole of three normal human eyes by reverse transcriptase-polymerase chain reaction. RESULTS: The immunohistochemical expression of sstA in newly formed endothelial cells and fibroblast-like cells was strong in fibrovascular CNV membranes. mRNA of sst subtypes 1, 2A, and 3, as well as somatostatin, was present in the normal posterior pole; sst subtypes 4 and 5 were not detectable. CONCLUSIONS: Most early-formed CNV in ARM express sst2A. The presence of mRNA of sst subtype 2A was observed in normal human macula, and subtypes 1 and 3 and somatostatin are also present. sst2A receptors bind potential anti-angiogenic somatostatin analogues such as octreotide. Therefore, somatostatin analogues may be an effective therapy in early stages of CNV in ARM. http://repub.eur.nl/res/pub/9527/ 2000-01-01T00:00:00Z http://repub.eur.nl/res/pub/8845/ 1998-01-01T00:00:00Z BACKGROUND/AIMS: Earlier studies on intraocular tissue have demonstrated that T lymphocytes play a major role in the pathogenesis of uveitis. Adhesion molecules are immunoregulatory molecules for the interaction between T lymphocytes and vascular endothelium and they play an important role in the recruitment of specific T lymphocytes from the circulation into inflamed tissue. In uveitis an increased expression of some of these adhesion molecules may be expected. METHODS: The presence of adhesion molecules was investigated in iris biopsy specimens from 11 patients with uveitis and eight controls (patients with primary open angle glaucoma) immunohistochemically with a panel of monoclonal antibodies: LECAM (CD 62L), ICAM-1 (CD 54), LFA-1 (CD 11a/18), VCAM-1 (CD 106), VLA-4 (CD 49d), and HECA-452, a marker for high endothelial venules. RESULTS: Positive staining for ICAM-1, LFA-1 and VCAM-1 was found in the iris in a significantly higher number of uveitis patients than in controls. The remaining adhesion molecules were also found in a higher number of uveitis patients than in controls, but this difference did not reach statistical significance. CONCLUSION: An increased expression of adhesion molecules was found in the iris of patients with uveitis, indicating an immunoregulatory function for adhesion molecules in the pathogenesis of uveitis.