Effects of tumor necrosis factor-α and interleukin-1ß on human retinal endothelial cells.

Uveitis, or intraocular inflammation, is a potentially blinding condition that mostly affects the working-age population. The cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1ß, play a role in the pathogenesis of non-infectious uveitis and have been linked to the breakdown of the inner blood-retinal barrier, composed mainly of retinal endothelial cells, leading to macular oedema and vascular leakage. However, the effects of TNF-α and IL-1ß on human retinal endothelial function are not fully understood. In this work, we investigated the impact of TNF-α and IL-1ß on several aspects of human retinal endothelial cell biology. Through a real-time biosensor, the impact of TNF-α and IL-1ß on formation of a retinal endothelial cell barrier was analyzed. Changes in junctional components were assessed via RT-qPCR and immunolabelling. Cell survival, necrosis and apoptosis were appraised via cell proliferation and flow cytometric studies. Tumor necrosis factor-α and IL-1ß impaired the electrical resistance of the retinal endothelial cell barrier, while the addition of a potentially barrier-impairing cytokine, IL-6, did not enhance the effect of TNF-α and IL-1ß. Level of the gene transcript encoding zonula occludens (ZO)-1 was diminished, while ZO-1 protein configuration was changed by TNF-α and IL-1ß. Both cytokines affected human retinal endothelial cell proliferation and viability, while only TNF-α increased rates of necrosis. These results indicate that TNF-α and IL-1ß are important drivers of retinal endothelial dysfunction in non-infectious uveitis, suggesting that targeting these cytokines is critical when treating complications of uveitis, such as macular oedema and vascular leakage.

Selective Transcription Factor Blockade Reduces Human Retinal Endothelial Cell Expression of Intercellular Adhesion Molecule-1 and Leukocyte Binding.

The interaction between leukocytes and cytokine-activated retinal endothelium is an initiating step in non-infectious uveitis involving the posterior eye, mediated by cell adhesion molecules. However, because cell adhesion molecules are required for immune surveillance, therapeutic interventions would ideally be employed indirectly. Using 28 primary human retinal endothelial cell isolates, this study sought to identify transcription factor targets for reducing levels of the key retinal endothelial cell adhesion molecule, intercellular adhesion molecule (ICAM)-1, and limiting leukocyte binding to the retinal endothelium. Five candidate transcription factors-C2CD4B, EGR3, FOSB, IRF1, and JUNB-were identified by differential expression analysis of a transcriptome generated from IL-1ß- or TNF-α-stimulated human retinal endothelial cells, interpreted in the context of the published literature. Further filtering involved molecular studies: of the five candidates, C2CD4B and IRF1 consistently demonstrated extended induction in IL-1ß- or TNF-α-activated retinal endothelial cells and demonstrated a significant decrease in both ICAM-1 transcript and ICAM-1 membrane-bound protein expression by cytokine-activated retinal endothelial cells following treatment with small interfering RNA. RNA interference of C2CD4B or IRF1 significantly reduced leukocyte binding in a majority of human retinal endothelial cell isolates stimulated by IL-1ß or TNF-α. Our observations suggest that the transcription factors C2CD4B and IRF1 may be potential drug targets for limiting leukocyte-retinal endothelial cell interactions in non-infectious uveitis involving the posterior eye.

Erratum to "Molecular Responses of Human Retinal Cells to Infection with Dengue Virus".

[This corrects the article DOI: 10.1155/2017/3164375.].

Emerging diagnostic tests for vitreoretinal lymphoma: a review.

Vitreoretinal lymphoma, which most commonly is diffuse large B-cell non-Hodgkin in type, is a rare cancer with high morbidity and high mortality. Making a tissue diagnosis of vitreoretinal lymphoma is a major challenge for clinicians due to biological and technical factors. Yet, the delay in start of treatment may have vision- and life-threatening consequences, and there is considerable interest in the application of molecular assays to improve the accuracy of the diagnostic process: detection of a clonal immunoglobulin heavy-chain rearrangements in lymphoma cells by polymerase chain reaction; measurement of vitreous or aqueous interleukin-10 protein levels in ocular fluids; and identification of mutations in the myeloid differentiation primary response gene 88 in tumour cells. In this article, we review the historical development and current application of each of these molecular methods. We also discuss future opportunities for the molecular diagnosis of vitreoretinal lymphoma through next-generation sequencing technologies.

Effect of NADPH oxidase 1 and 4 blockade in activated human retinal endothelial cells.

BACKGROUND: Over-production of reactive oxygen species (ROS) and resulting oxidative stress contribute to retinal damage in vascular diseases that include diabetic retinopathy, retinopathy of prematurity and major retinal vessel occlusions. NADPH oxidase (Nox) proteins are professional ROS-generating enzymes, and therapeutic targeting in these diseases has strong appeal. Pharmacological inhibition of Nox4 reduces the severity of experimental retinal vasculopathy. We investigated the potential application of this drug approach in humans. METHODS: Differential Nox enzyme expression was studied by real-time-quantitative polymerase chain reaction in primary human retinal endothelial cell isolates and a characterized human retinal endothelial cell line. Oxidative stress was triggered chemically in endothelial cells, by treatment with dimethyloxalylglycine (DMOG; 100 µM); Nox4 and vascular endothelial growth factor (VEGFA) transcript were measured; and production of ROS was detected by 2',7'-dichlorofluorescein. DMOG-stimulated endothelial cells were treated with two Nox1/Nox4 inhibitors, GKT136901 and GKT137831; cell growth was monitored by DNA quantification, in addition to VEGFA transcript and ROS production. RESULTS: Nox4 (isoform Nox4A) was the predominant Nox enzyme expressed by human retinal endothelial cells. Treatment with DMOG significantly increased endothelial cell expression of Nox4 over 72 h, accompanied by ROS production and increased VEGFA expression. Treatment with GKT136901 or GKT137831 significantly reduced DMOG-induced ROS production and VEGFA expression by endothelial cells, and the inhibitory effect of DMOG on cell growth. CONCLUSIONS: Our findings in experiments on activated human retinal endothelial cells provide translational corroboration of studies in experimental models of retinal vasculopathy and support the therapeutic application of Nox4 inhibition by GKT136901 and GKT137831 in patients with retinal vascular diseases.

Molecular Responses of Human Retinal Cells to Infection with Dengue Virus.

Recent clinical reports indicate that infection with dengue virus (DENV) commonly has ocular manifestations. The most serious threat to vision is dengue retinopathy, including retinal vasculopathy and macular edema. Mechanisms of retinopathy are unstudied, but observations in patients implicate retinal pigment epithelial cells and retinal endothelial cells. Human retinal cells were inoculated with DENV-2 and monitored for up to 72 hours. Epithelial and endothelial cells supported DENV replication and release, but epithelial cells alone demonstrated clear cytopathic effect, and infection was more productive in those cells. Infection induced type I interferon responses from both cells, but this was stronger in epithelial cells. Endothelial cells increased expression of adhesion molecules, with sustained overexpression of vascular adhesion molecule-1. Transcellular impedance decreased for epithelial monolayers, but not endothelial monolayers, coinciding with cytopathic effect. This reduction was accompanied by disorganization of intracellular filamentous-actin and decreased expression of junctional molecules, zonula occludens 1, and catenin-ß1. Changes in endothelial expression of adhesion molecules are consistent with the retinal vasculopathy seen in patients infected with DENV; decreases in epithelial junctional protein expression, paralleling loss of integrity of the epithelium, provide a molecular basis for DENV-associated macular edema. These molecular processes present potential therapeutic targets for vision-threatening dengue retinopathy.

Targeting Endothelial Adhesion Molecule Transcription for Treatment of Inflammatory Disease: A Proof-of-Concept Study.

Targeting the endothelial adhesion molecules that control leukocyte trafficking into a tissue has been explored as a biological therapy for inflammatory diseases. However, these molecules also participate in leukocyte migration for immune surveillance, and inhibiting the physiological level of an adhesion molecule might promote infection or malignancy. We explored the concept of targeting endothelial adhesion molecule transcription during inflammation in a human system. Intercellular adhesion molecule 1 (ICAM-1) mediates leukocyte migration across the retinal endothelium in noninfectious posterior uveitis. We observed an increase in the transcription factor, nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NF-κB1), in parallel with ICAM-1, in human retinal endothelial cells treated with tumor necrosis factor-alpha (TNF-α), and identified putative binding sites for NF-κB1 within the ICAM-1 regulatory region. We targeted induced NF-κB1 expression in endothelial cells with small interfering (si)RNA. Knockdown of NF-κB1 significantly decreased cell surface expression of ICAM-1 protein induced by TNF-α but did not reduce constitutive ICAM-1 expression. Consistently, NF-κB1 knockdown significantly reduced leukocyte binding to cell monolayers in the presence of TNF-α but did not impact baseline binding. Findings of this proof-of-concept study indicate that induced transcription of endothelial adhesion molecules might be targeted therapeutically for inflammatory disease in humans.

Genome-wide association study for sight-threatening diabetic retinopathy reveals association with genetic variation near the GRB2 gene.

AIMS/HYPOTHESIS: Diabetic retinopathy is a serious complication of diabetes mellitus and can lead to blindness. A genetic component, in addition to traditional risk factors, has been well described although strong genetic factors have not yet been identified. Here, we aimed to identify novel genetic risk factors for sight-threatening diabetic retinopathy using a genome-wide association study. METHODS: Retinopathy was assessed in white Australians with type 2 diabetes mellitus. Genome-wide association analysis was conducted for comparison of cases of sight-threatening diabetic retinopathy (n = 336) with diabetic controls with no retinopathy (n = 508). Top ranking single nucleotide polymorphisms were typed in a type 2 diabetes replication cohort, a type 1 diabetes cohort and an Indian type 2 cohort. A mouse model of proliferative retinopathy was used to assess differential expression of the nearby candidate gene GRB2 by immunohistochemistry and quantitative western blot. RESULTS: The top ranked variant was rs3805931 with p = 2.66 × 10(-7), but no association was found in the replication cohort. Only rs9896052 (p = 6.55 × 10(-5)) was associated with sight-threatening diabetic retinopathy in both the type 2 (p = 0.035) and the type 1 (p = 0.041) replication cohorts, as well as in the Indian cohort (p = 0.016). The study-wide meta-analysis reached genome-wide significance (p = 4.15 × 10(-8)). The GRB2 gene is located downstream of this variant and a mouse model of retinopathy showed increased GRB2 expression in the retina. CONCLUSIONS/INTERPRETATION: Genetic variation near GRB2 on chromosome 17q25.1 is associated with sight-threatening diabetic retinopathy. Several genes in this region are promising candidates and in particular GRB2 is upregulated during retinal stress and neovascularisation.

Simultaneous visualization and cell-specific confirmation of RNA and protein in the mouse retina.

PURPOSE: Simultaneous dual labeling to visualize specific RNA and protein content within the same formalin-fixed paraffin embedded (FFPE) section can be technically challenging and usually impossible, because of variables such as tissue fixation time and pretreatment methods to access the target RNA or protein. Within a specific experiment, ocular tissue sections can be a precious commodity. Thus, the ability to easily and consistently detect and localize cell-specific expression of RNA and protein within a single slide would be advantageous. In this study, we describe a simplified and reliable method for combined in situ hybridization (ISH) and immunohistochemistry (IHC) for detection of mRNA and protein, respectively, within the same FFPE ocular tissue. METHODS: Whole mouse eyes were prepared for 5 micron FFPE sections after fixation for 3, 24, 48 or 72 h. Customized probes from Advanced Cell Diagnostics to detect mRNA for vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1-alpha (HIF-1α), and hypoxia-inducible factor 2-alpha (HIF-2α) were used for ISH. Various parameters were tested using the novel RNAscope method for ISH and optimized for compatibility with subsequent IHC for glial fibrillary acidic protein (GFAP) or GS-lectin within the same tissue section. Dual fluorescent visualization of Fast Red ISH and Alexa Fluor 488 IHC signal was observed with confocal microscopy. RESULTS: A fixation time of 72 h was found to be optimal for ISH and subsequent IHC. The RNAscope probes for VEGF, HIF-1α, and HIF-2α mRNA all gave a strong Fast Red signal with both 48 h and 72 h fixed tissue, but the optimal IHC signal for either GFAP or GS-lectin within a retinal tissue section after ISH processing was observed with 72 h fixation. A pretreatment boiling time of 15 min and a dilution factor of 1:15 for the pretreatment protease solution were found to be optimal and necessary for successful ISH visualization with 72 h FFPE ocular tissue. CONCLUSIONS: The protocol presented here provides a simple and reliable method to simultaneously detect mRNA and protein within the same paraffin-embedded ocular tissue section. The procedure, after preparation of FFPE sections, can be performed over a 2-day or 4-day period. We provide an optimization strategy that may be adapted for any RNAscope probe set and antibody for determining retinal or ocular cell-specific patterns of expression.

Sequence- and target-independent angiogenesis suppression by siRNA via TLR3.

Clinical trials of small interfering RNA (siRNA) targeting vascular endothelial growth factor-A (VEGFA) or its receptor VEGFR1 (also called FLT1), in patients with blinding choroidal neovascularization (CNV) from age-related macular degeneration, are premised on gene silencing by means of intracellular RNA interference (RNAi). We show instead that CNV inhibition is a siRNA-class effect: 21-nucleotide or longer siRNAs targeting non-mammalian genes, non-expressed genes, non-genomic sequences, pro- and anti-angiogenic genes, and RNAi-incompetent siRNAs all suppressed CNV in mice comparably to siRNAs targeting Vegfa or Vegfr1 without off-target RNAi or interferon-alpha/beta activation. Non-targeted (against non-mammalian genes) and targeted (against Vegfa or Vegfr1) siRNA suppressed CNV via cell-surface toll-like receptor 3 (TLR3), its adaptor TRIF, and induction of interferon-gamma and interleukin-12. Non-targeted siRNA suppressed dermal neovascularization in mice as effectively as Vegfa siRNA. siRNA-induced inhibition of neovascularization required a minimum length of 21 nucleotides, a bridging necessity in a modelled 2:1 TLR3-RNA complex. Choroidal endothelial cells from people expressing the TLR3 coding variant 412FF were refractory to extracellular siRNA-induced cytotoxicity, facilitating individualized pharmacogenetic therapy. Multiple human endothelial cell types expressed surface TLR3, indicating that generic siRNAs might treat angiogenic disorders that affect 8% of the world's population, and that siRNAs might induce unanticipated vascular or immune effects.

Brief research report: ETS-1 blockade increases ICAM-1 expression in activated human retinal endothelial cells.

Intercellular adhesion molecule 1 (ICAM-1) is a central cell adhesion molecule for retinal transendothelial migration of the leukocytes in non-infectious posterior uveitis. Inhibiting ICAM1 gene transcription reduces induction of ICAM-1 in inflamed retinal endothelium. Based on published literature implicating transcription factor ETS-1 as an activator of ICAM1 gene transcription, we investigated the effect of ETS-1 blockade on ICAM-1 levels in cytokine-stimulated human retinal endothelial cells. We first examined ICAM1 and ETS1 transcript expression in human retinal endothelial cells exposed to tumor necrosis factor-alpha (TNF-α) or interleukin-1beta (IL-1ß). ICAM1 and ETS1 transcripts were increased in parallel in primary human retinal endothelial cell isolates (n = 5) after a 4-hour stimulation with TNF-α or IL-1ß (p ≤ 0.012 and ≤ 0.032, respectively). We then assessed the effect of ETS-1 blockade by small interfering (si)RNA on cellular ICAM1 transcript and membrane-bound ICAM-1 protein. ETS1 transcript was reduced by greater than 90% in cytokine-stimulated and non-stimulated human retinal endothelial cell monolayers following a 48-hour treatment with two ETS-1-targeted siRNA, in comparison to negative control non-targeted siRNA (p ≤ 0.0002). The ETS-1 blockade did not reduce ICAM1 transcript expression nor levels of membrane-bound ICAM-1 protein, rather it increased both for a majority of siRNA-treatment and cytokine-stimulation conditions (p ≤ 0.018 and ≤ 0.004, respectively). These unexpected findings indicate that ETS-1 blockade increases ICAM-1 transcript and protein levels in human retinal endothelial cells. Thus ETS-1-targeting would be expected to promote rather than inhibit retinal transendothelial migration of leukocytes in non-infectious posterior uveitis.

Disease profiles in the Indigenous Australian population are suggestive of a common complement control haplotype.

Aboriginal and Torres Strait Islander People (respectfully referred to as Indigenous Australians herein) are disparately burdened by many infectious and chronic diseases relative to Australians with European genetic ancestry. Some of these diseases are described in other populations to be influenced by the inherited profile of complement genes. These include complement factor B, H, I and complement factor H-related (CFHR) genes that can contribute to a polygenic complotype. Here the focus is on the combined deletion of CFHR1 and 3 to form a common haplotype (CFHR3-1Δ). The prevalence of CFHR3-1Δ is high in people with Nigerian and African American genetic ancestry and correlates to a higher frequency and severity of systemic lupus erythematosus (SLE) but a lower prevalence of age-related macular degeneration (AMD) and IgA-nephropathy (IgAN). This pattern of disease is similarly observed among Indigenous Australian communities. Additionally, the CFHR3-1Δ complotype is also associated with increased susceptibility to infection with pathogens, such as Neisseria meningitidis and Streptococcus pyogenes, which also have high incidences in Indigenous Australian communities. The prevalence of these diseases, while likely influenced by social, political, environmental and biological factors, including variants in other components of the complement system, may also be suggestive of the CFHR3-1Δ haplotype in Indigenous Australians. These data highlight a need to define the Indigenous Australian complotypes, which may lead to the discovery of new risk factors for common diseases and progress towards precision medicines for treating complement-associated diseases in Indigenous and non-Indigenous populations. Herein, the disease profiles suggestive of a common complement CFHR3-1Δ control haplotype are examined.

Expression of Long Non-Coding RNAs in Activated Human Retinal Vascular Endothelial Cells.

PURPOSE: Retinal endothelial cell activation is a central event in non-infectious posterior uveitis. There is recent interest in long non-coding (lnc)RNA-targeted therapeutics for retinal diseases. We aimed to identify human retinal endothelial cell lncRNAs that might be involved in activation. METHODS: Eleven candidate lncRNAs were identified: GAS5, KCNQ1OT1, LINC00294, MALAT1, MEG3, MIR155HG, NEAT1, NORAD, OIP5-AS1, SENCR, TUG1. Expression was assessed by RT-PCR in human retinal endothelial cells, at baseline and following activation with interleukin (IL)-1ß and tumor necrosis factor (TNF)-α. RESULTS: IL-1ß significantly upregulated MEG3 and SENCR at 4 and 24 hours; LINC00294, NORAD, OIP5-AS1 and TUG1 at 24 hours; and MIR155HG at 4, 24 and 48 hours; but downregulated GAS5 at 24 and 48 hours. TNF-α significantly upregulated KCNQ1OT1, LINC00294, MEG3, NORAD and SENCR at 4 hours; SENCR and TUG1 at 24 hours; and MIR155HG at all time points. CONCLUSIONS: Future studies involving manipulation of MIR155HG may be warranted to explore potential therapeutic applications for non-infectious posterior uveitis.

Human retinal endothelial cells express functional interleukin-6 receptor.

BACKGROUND: Interleukin (IL)-6 is an inflammatory cytokine present in the eye during non-infectious uveitis, where it contributes to the progression of inflammation. There are two major IL-6 signaling pathways: classic signaling and trans-signaling. Classic signaling requires cellular expression of the IL-6 receptor (IL-6R), which exists in membrane-bound (mIL-6R) and soluble (sIL-6R) forms. Prevailing dogma is that vascular endothelial cells do not produce IL-6R, relying on trans-signaling during inflammation. However, the literature is inconsistent, including with respect to human retinal endothelial cells. FINDINGS: We examined IL-6R transcript and protein expression in multiple primary human retinal endothelial cell isolates, and assessed the effect of IL-6 on the transcellular electrical resistance of monolayers. Using reverse transcription-polymerase chain reaction, IL-6R, mIL-6R and sIL-6R transcripts were amplified in 6  primary human retinal endothelial isolates. Flow cytometry on 5 primary human retinal endothelial cell isolates under non-permeabilizing conditions and following permeabilization demonstrated intracellular stores of IL-6R and the presence of mIL-6R. When measured in real-time, transcellular electrical resistance of an expanded human retinal endothelial cell isolate, also shown to express IL-6R, decreased significantly on treatment with recombinant IL-6 in comparison to non-treated cells across 5 independent experiments. CONCLUSIONS: Our findings indicate that human retinal endothelial cells produce IL-6R transcript and functional IL-6R protein. The potential for classic signaling in human retinal endothelial cells has implications for the development of therapeutics targeted against IL-6-mediated pathology in non-infectious uveitis.

Expression and regulation of activated leukocyte cell adhesion molecule in human retinal vascular endothelial cells.

Activated leukocyte cell adhesion molecule (ALCAM; CD166) is an immunoglobulin superfamily member that has been described in several non-ocular endothelial populations, but not in relation to endothelium within the eye. Studies in extraocular systems have implicated ALCAM in angiogenesis and leukocyte transendothelial migration, which are key processes in retinal vascular diseases. We investigated the expression of ALCAM in human retinal endothelium, and studied the regulation of expression by established angiogenic and inflammatory stimuli. Retinal endothelial expression of ALCAM was detected in primary retinal endothelial cultures isolated from human cadavers by RT-PCR (n = 4 donors) and Western blot (n = 4 donors), and in intact human retina by immunohistochemistry (n = 3 donors). In the 4 donors studied by RT-PCR, transcript encoding the truncated soluble isoform, sALCAM, was also detected. Quantitative real-time RT-PCR demonstrated significant up-regulation of ALCAM and sALCAM in response to stimulation with master cytokine, tumor necrosis factor (TNF)-α. However, general inflammatory stimulus, lipopolysaccharide (LPS), and the prototype Th1, Th2 and Th17 cytokines, interferon (IFN)-γ, interleukin (IL)-4 and IL-17A, respectively, did not impact ALCAM or sALCAM expression. In contrast, expression of ALCAM was significantly up-regulated by vascular endothelial growth factor (VEGF)(165). Up-regulation in the presence of VEGF and TNF-α, but not LPS, IFN-γ, IL-4 and IL-17A, suggests a potential role for ALCAM in human retinal angiogenesis in some settings.

Transcriptomic Responses of Human Retinal Vascular Endothelial Cells to Inflammatory Cytokines.

Purpose: Molecular profiling of human retinal endothelial cells provides opportunities to understand the roles of this cell population in maintenance of the blood-ocular barrier, and its involvements in diverse retinal vasculopathies. We aimed to generate a transcriptome of human retinal endothelial cells in the unstimulated state, and following treatment with inflammatory cytokines linked to cell dysfunction. Methods: Endothelial cells were isolated from retinae of five human cadaveric donors, and treated for 60 minutes and 24 hours with interleukin-1ß or tumor necrosis factor-α, or exposed to medium alone for the same intervals. Expression of intercellular adhesion molecule-1 was measured by RT-qPCR to confirm cytokine-induced activation of the cells. RNA was sequenced on the Illumina NovaSeq 6000 platform. Reads were aligned to the human GRCh38 genome, and reads that aligned to Ensembl-annotated genes were counted. Quality control of sequencing was performed with FastQC, and sequences were classified by Kraken. Results: A human retinal endothelial cell RNA-sequencing dataset with mean of 99% reads aligned to the human genome was produced as raw RNA sequence data (FASTQ files) and processed read data (XLSX files). Multidimensional scaling analysis showed a strong donor effect, which was readily controlled by ComBat. Conclusions: Our dataset may be useful for human retinal endothelial cell transcriptomic assemblies, functional gene annotating and/or gene expression and enrichment analyses, as well as cross-dataset harmonization. Translational Relevance: The molecular profile of the human retinal endothelium is a source of candidate biologic targets for retinal vasculopathies.

Infection of Human Retinal Pigment Epithelial Cells with Dengue Virus Strains Isolated during Outbreaks in Singapore.

Prevalence of dengue retinopathy varies across epidemics, with the disease linked to circulation of dengue virus serotype 1 (DENV-1). The retinal pigment epithelium has been implicated in the pathology. We investigated infectivity, molecular response, and barrier function of epithelial cells inoculated with DENV strains from different outbreaks in Singapore. Monolayers of human retinal pigment epithelial cells (multiple primary cell isolates and the ARPE-19 cell line) were inoculated with six DENV strains, at multiplicity of infection of 10; uninfected and recombinant strain-infected controls were included where relevant. Infectivity and cell response were assessed primarily by RT-qPCR on total cellular RNA, and barrier function was evaluated as electrical resistance across monolayers. Higher viral RNA loads were measured in human retinal pigment epithelial cells infected with DENV-1 strains from the 2005 Singapore epidemic, when retinopathy was prevalent, versus DENV-1 strains from the 2007 Singapore epidemic, when retinopathy was not observed. Type I interferon (IFN) transcripts (IFN-ß and multiple IFN-stimulated genes) were up-regulated, and impact on barrier function was more pronounced, for cells infected with DENV-1 strains from the 2005 versus the 2007 Singapore epidemics. Aside from serotype, strain of DENV may determine the potential to induce retinal pathology. Identification of molecular markers of disease-associated DENV strains may provide insights into the pathogenesis of dengue retinopathy.

Zika Virus Infection of Human Iris Pigment Epithelial Cells.

During recent Zika epidemics, adults infected with Zika virus (ZIKV) have developed organ-specific inflammatory complications. The most serious Zika-associated inflammatory eye disease is uveitis, which is commonly anterior in type, affecting both eyes and responding to corticosteroid eye drops. Mechanisms of Zika-associated anterior uveitis are unknown, but ZIKV has been identified in the aqueous humor of affected individuals. The iris pigment epithelium is a target cell population in viral anterior uveitis, and it acts to maintain immune privilege within the anterior eye. Interactions between ZIKV and human iris pigment epithelial cells were investigated with infectivity assays and RNA-sequencing. Primary cell isolates were prepared from eyes of 20 cadaveric donors, and infected for 24 hours with PRVABC59 strain ZIKV or incubated uninfected as control. Cytoimmunofluorescence, RT-qPCR on total cellular RNA, and focus-forming assays of culture supernatant showed cell isolates were permissive to infection, and supported replication and release of infectious ZIKV. To explore molecular responses of cell isolates to ZIKV infection at the whole transcriptome level, RNA was sequenced on the Illumina NextSeq 500 platform, and results were aligned to the human GRCh38 genome. Multidimensional scaling showed clear separation between transcriptomes of infected and uninfected cell isolates. Differential expression analysis indicated a vigorous molecular response of the cell to ZIKV: 7,935 genes were differentially expressed between ZIKV-infected and uninfected cells (FDR < 0.05), and 99% of 613 genes that changed at least two-fold were up-regulated. Reactome and KEGG pathway and Gene Ontology enrichment analyses indicated strong activation of viral recognition and defense, in addition to biosynthesis processes. A CHAT network included 6275 molecular nodes and 24 contextual hubs in the cell response to ZIKV infection. Receptor-interacting serine/threonine kinase 1 (RIPK1) was the most significantly connected contextual hub. Correlation of gene expression with read counts assigned to the ZIKV genome identified a negative correlation between interferon signaling and viral load across isolates. This work represents the first investigation of mechanisms of Zika-associated anterior uveitis using an in vitro human cell model. The results suggest the iris pigment epithelium mounts a molecular response that limits intraocular pathology in most individuals.

Rhesus monkeys and humans share common susceptibility genes for age-related macular disease.

Age-related macular degeneration (AMD), a complex multigenic disorder and the most common cause of vision loss in the elderly, is associated with polymorphisms in the LOC387715/ARMS2 and HTRA1 genes on 10q26. Like humans, macaque monkeys possess a macula and develop age-related macular pathologies including drusen, the phenotypic hallmark of AMD. We genotyped a cohort of 137 unrelated rhesus macaques with and without macular drusen. As in humans, one variant within LOC387715/ARMS2 and one in HTRA1 were significantly associated with affected status. HTRA1 and the predicted LOC387715/ARMS2 gene were both transcribed in rhesus and human retina and retinal pigment epithelium. Among several primate species, orthologous exons for the human LOC387715/ARMS2 gene were present only in Old World monkeys and apes. In functional analyses, the disease-associated HTRA1 polymorphism resulted in a 2-fold increase in gene expression, supporting a role in pathogenesis. These results demonstrate that two genes associated with AMD in humans are also associated with macular disease in rhesus macaques and that one of these genes is specific to higher primates. This is the first evidence that humans and macaques share the same genetic susceptibility factors for a common complex disease.

Lamb as a potential source of Toxoplasma gondii infection for Australians.

OBJECTIVE: Toxoplasmosis may follow consumption of undercooked meat containing Toxoplasma gondii cysts. Lamb is considered to pose the highest risk for contamination across meats. Red meat is often served undercooked, yet there are no current data on T. gondii contamination of Australian sourced and retailed lamb. We sought to address this gap in public health knowledge. METHODS: Lamb mincemeat was purchased at the supermarket counter three times weekly for six months. T. gondii was detected by real-time polymerase chain reaction (PCR) of DNA extracted from the meat following homogenisation. Purchases were also tested for common foodborne bacterial pathogens. RESULTS: Conservative interpretation of PCR testing (i.e. parasite DNA detected in three of four tests) gave a probability of 43% (95% confidence interval, 32%-54%) that lamb mincemeat was contaminated with T. gondii. None of the purchases were contaminated with Campylobacter jejuni, Salmonella species or S. enterica serovar Typhimurium, indicating sanitary meat processing. CONCLUSIONS: Australian lamb is commonly contaminated with T. gondii. Future studies should be directed at testing a range of red meats and meat cuts. Implications for public health: Consuming undercooked Australian lamb has potential to result in toxoplasmosis. There may be value in health education around this risk.