Measuring Inflammation in the Vitreous and Retina: A Narrative Review.

Uveitis consists of a group of syndromes characterised by intraocular inflammation, accounting for up to 15% of visual loss in the western world and 10% worldwide. Assessment of intraocular inflammation has been limited to clinician-dependent, subjective grading. Developments in imaging technology, such as optical coherence tomography (OCT), have enabled the development of objective, quantitative measures of inflammatory activity. Important quantitative metrics including central macular thickness and vitreous signal intensity allow longitudinal monitoring of disease activity and can be used in conjunction with other imaging modalities enabling holistic assessment of ocular inflammation. Ongoing work into the validation of instrument-based measures alongside development of core outcome sets is crucial for standardisation of clinical trial endpoints and developing guidance for quantitative multi-modal imaging approaches. This review outlines methods of grading inflammation in the vitreous and retina, with a focus on the use of OCT as an objective measure of disease activity.

Topical Anti-Inflammatory Agents for Non-Infectious Uveitis: Current Treatment and Perspectives.

Non-infectious uveitis represents a heterogenous group of immune-mediated ocular diseases, which can be associated with underlying systemic disease. While the initial choice of treatment of non-infectious uveitis depends on a number of factors such as anatomical location and degree of inflammation, topical therapies often remain the initial choice of non-invasive therapy. In this narrative review, we aim to describe the literature on non-infectious uveitis, with specific focus on the current perspective on topical anti-inflammatory therapy.

Activated adult microglia influence retinal progenitor cell proliferation and differentiation toward recoverin-expressing neuron-like cells in a co-culture model.

PURPOSE: Microglia contribute to immune homeostasis of the retina, and thus act as a potential regulator determining successful repair or retinal stem cell transplantation. We investigated the interaction between human microglia and retinal progenitor cells in cell co-culture to further our exploration on developing a new therapeutic strategy for retinal degeneration. METHODS: Microglia and retinal progenitor cultures were developed using CD11b(+) and CD133(+), respectively, from adult donor retina. Microglia activation was developed using interferon-gamma and lipopolysaccharide. Retinal progenitor differentiation was analysed in co-culture with or without microglial activation. Retinal progenitor proliferation was analysed in presence of conditioned medium from activated microglia. Phenotype and function of adult human retinal cell cultures were examined using cell morphology, immunohistochemistry and real-time PCR. RESULTS: By morphology, neuron-like cells generated in co-culture expressed photoreceptor marker recoverin. Neurospheres derived from retinal progenitor cells showed reduced growth in the presence of conditioned medium from activated microglia. Delayed retinal progenitor cell migration and reduced cellular differentiation was observed in co-cultures with activated microglia. In independent experiments, activated microglia showed enhanced mRNA expression of CXCL10, IL-27, IL-6, and TNF-alpha compared to controls. CONCLUSION: Adult human retina retains retinal progenitors or potential to reprogram cells to then proliferate and differentiate into neuron-like cells in vitro. Human microglia support retinal progenitor differentiation into neuron-like cells, but such capacity is altered following microglial activation. Modulating microglia activity is a potential approach to promote retinal repair and facilitate success of stem-cell transplantation.

Functional analysis of retinal microglia and their effects on progenitors.

The identification of stem/progenitor cells within the retinal neural environment has opened up the possibility of therapy via cellular replacement and/or reprogramming of resident cell populations. Within the neuro-retinal niche, following injury or in disease states (including inflammation and degeneration), cellular responses affect tissue homeostasis, reduce cell density, disrupt tissue architecture, and produce scar formation. Microglia (resident retinal immune cell tissue macrophage) are key to the maintenance of retinal homeostasis and are implicated in responses that may influence the control and behavior of retinal progenitors. Factors to consider in the generation of a transplantable cell resource with good migratory and integrative capacity include their yield, purity, and functional viability. Utilizing human postmortem retina, we have created a research platform to isolate, culture, and characterize adult retinal microglia as well as analyze their effect on retinal progenitors. Here, we describe techniques using magnetic labeled bead cell separation to isolate pure populations of retinal CD133(+) precursor cells and CD11b(+) microglia from primary adult retinal cell suspensions (RCSs), enabling flow cytometric cell phenotypic and qPCR genotypic analysis, as well as functional analysis by real-time ratiometric calcium imaging.

Microglia derived IL-6 suppresses neurosphere generation from adult human retinal cell suspensions.

Following retinal degeneration or inflammation that disrupts tissue architecture, there is limited evidence of tissue regeneration, despite evidence of cells with progenitor properties in the adult human retina at all ages. With the prospect of tissue/cell transplantation, redressing homeostasis whilst overcoming glial barrier or gliosis remains key to successful graft versus host integration and functional recovery. Activated human retinal microglia (MG) secrete cytokines, including IL-6, which may suppress neurogenesis or cellular (photoreceptor) replacement. To investigate this hypothesis, adult human retinal explants were cultured in cytokine-conditioned media (TNFalpha, TGFbeta, LPS/IFNgamma) to activate microglia in situ. Following culture of retinal explants for 4 days, supernatant conditioned by resulting migrated microglia was collected after a further 3 days and fed to retinal cell suspensions (RCS). Neurosphere (NS) generation and survival analysis was performed after 7 and 14 days in culture, with or without addition of conditioned media and with or without concomitant IL-6 neutralisation. Neurosphere phenotype was analysed by immunohistochemistry and cell morphology. Migratory MG from retinal explants were activated (iNOS-positive) and expressed CD45, CD11b, and CD11c. LPS/IFNgamma-activated MG conditioned media (MG-CM) contained significant levels of IL-6 (1265 +/- 143) pg/ml, which inhibited neurosphere generation within RCS in the presence of optimal neurosphere generating N2-FGF2 culture medium. Neutralising IL-6 activity reinstated NS generation and the differentiation capacity was maintained in the spheres that formed. Even in the presence of high levels of IL-6, those few NS that did form demonstrated a capacity to differentiate. The data supports activated MG-derived IL-6 influence retinal cell turnover.

Five-year retrospective review of guideline-based management of fungal endophthalmitis.

PURPOSE: Guidelines were introduced in 2000 at the Bristol Eye Hospital (BEH) for the management of fungal endophthalmitis. A 5-year retrospective audit re-evaluated the guidelines and monitored the management of this rare condition. Clinical effectiveness and management costs were considered in light of visual outcome. METHODS: Cases were identified through a 5-year retrospective review of theatre logbooks, Patient Administration System coded admissions with primary diagnosis of purulent endophthalmitis and pharmacy logbooks of patients receiving antifungal therapy. Data correlation and review of patient management were carried out in light of the findings. RESULTS: Twenty-three cases were included, based on clinical disease and/or positive smears or cultures. Age range was 13-74 years, with a male : female ratio of 16 : 7 and right eye : left eye ratio of 14 : 9. Risk factors for fungal endophthalmitis included septicaemia caused by intravenous drug use (78%), presence of indwelling lines (9%), postocular surgery (9%) and post-trauma (4%). Guidelines were rigidly followed in 56% of cases, with improved visual acuity in 9/13 patients compared to 4/10 where management deviated from guidelines. Deviation from guidelines occurred with incomplete use of the recommended drug regimen for the disease severity or use of drugs that were alternative to the suggested guidelines. Treatment was initiated on clinical judgement in 91% of cases and laboratory diagnosis in 9%. CONCLUSION: The BEH guidelines provided a useful reference when managing this uncommon condition. Voriconazole, a newer broad-spectrum agent with good ocular penetration (used in 9%), has been added to the revised guidelines. Monitoring rare conditions over prolonged time frames supports evidence-based medicine