Characterization of the angiomodulatory effects of Interleukin 11 cis- and trans-signaling in the retina.

BACKGROUND: The IL-6 cytokine family, with its crucial and pleiotropic intracellular signaling pathway STAT3, is a promising target for treating vasoproliferative retinal diseases. Previous research has shown that IL-6 cis-signaling (via membrane-bound receptors) and trans-signaling (via soluble receptors) can have distinct effects on target cells, leading to their application in various disease treatments. While IL-6 has been extensively studied, less is known about the angiogenic effects of IL-11, another member of the IL-6 family, in the retina. Therefore, the aim of this study was to characterize the effects of IL-11 on retinal angiogenesis. MAIN TEXT: In vitreous samples from proliferative diabetic retinopathy (PDR) patients, elevated levels of IL-11Rα, but not IL-11, were detected. In vitro studies using vascular endothelial cells revealed distinct effects of cis- and trans-signaling: cis-signaling (IL-11 alone) had antiangiogenic effects, while trans-signaling (IL-11 + sIL-11Rα) had proangiogenic and pro-migratory effects. These differences can be attributed to their individual signaling responses and associated transcriptomic changes. Notably, no differences in cis- and trans-signaling were detected in primary mouse Müller cell cultures. STAT3 and STAT1 siRNA knockdown experiments revealed opposing effects on IL-11 signaling, with STAT3 functioning as an antiproliferative and proapoptotic player while STAT1 acts in opposition to STAT3. In vivo, both IL-11 and IL-11 + sIL-11Rα led to a reduction in retinal neovascularization. Immunohistochemical staining revealed Müller cell activation in response to treatment, suggesting that IL-11 affects multiple retinal cell types in vivo beyond vascular endothelial cells. CONCLUSIONS: Cis- and trans-signaling by IL-11 have contrasting angiomodulatory effects on endothelial cells in vitro. In vivo, cis- and trans-signaling also influence Müller cells, ultimately determining the overall angiomodulatory impact on the retina, highlighting the intricate interplay between vascular and glial cells in the retina.

Redefining the ontogeny of hyalocytes as yolk sac-derived tissue-resident macrophages of the vitreous body.

BACKGROUND: The eye is a highly specialized sensory organ which encompasses the retina as a part of the central nervous system, but also non-neural compartments such as the transparent vitreous body ensuring stability of the eye globe and a clear optical axis. Hyalocytes are the tissue-resident macrophages of the vitreous body and are considered to play pivotal roles in health and diseases of the vitreoretinal interface, such as proliferative vitreoretinopathy or diabetic retinopathy. However, in contrast to other ocular macrophages, their embryonic origin as well as the extent to which these myeloid cells might be replenished by circulating monocytes remains elusive. RESULTS: In this study, we combine transgenic reporter mice, embryonic and adult fate mapping approaches as well as parabiosis experiments with multicolor immunofluorescence labeling and confocal laser-scanning microscopy to comprehensively characterize the murine hyalocyte population throughout development and in adulthood. We found that murine hyalocytes express numerous well-known myeloid cell markers, but concomitantly display a distinct immunophenotype that sets them apart from retinal microglia. Embryonic pulse labeling revealed a yolk sac-derived origin of murine hyalocytes, whose precursors seed the developing eye prenatally. Finally, postnatal labeling and parabiosis established the longevity of hyalocytes which rely on Colony Stimulating Factor 1 Receptor (CSF1R) signaling for their maintenance, independent of blood-derived monocytes. CONCLUSION: Our study identifies hyalocytes as long-living progeny of the yolk sac hematopoiesis and highlights their role as integral members of the innate immune system of the eye. As a consequence of their longevity, immunosenescence processes may culminate in hyalocyte dysfunction, thereby contributing to the development of vitreoretinal diseases. Therefore, myeloid cell-targeted therapies that convey their effects through the modification of hyalocyte properties may represent an interesting approach to alleviate the burden imposed by diseases of the vitreoretinal interface.

Hyalocytes-guardians of the vitreoretinal interface.

Originally discovered in the nineteenth century, hyalocytes are the resident macrophage cell population in the vitreous body. Despite this, a comprehensive understanding of their precise function and immunological significance has only recently emerged. In this article, we summarize recent in-depth investigations deciphering the critical role of hyalocytes in various aspects of vitreous physiology, such as the molecular biology and functions of hyalocytes during development, adult homeostasis, and disease. Hyalocytes are involved in fetal vitreous development, hyaloid vasculature regression, surveillance and metabolism of the vitreoretinal interface, synthesis and breakdown of vitreous components, and maintenance of vitreous transparency. While sharing certain resemblances with other myeloid cell populations such as retinal microglia, hyalocytes possess a distinct molecular signature and exhibit a gene expression profile tailored to the specific needs of their host tissue. In addition to inflammatory eye diseases such as uveitis, hyalocytes play important roles in conditions characterized by anomalous posterior vitreous detachment (PVD) and vitreoschisis. These can be hypercellular tractional vitreo-retinopathies, such as macular pucker, proliferative vitreo-retinopathy (PVR), and proliferative diabetic vitreo-retinopathy (PDVR), as well as paucicellular disorders such as vitreo-macular traction syndrome and macular holes. Notably, hyalocytes assume a significant role in the early pathophysiology of these disorders by promoting cell migration and proliferation, as well as subsequent membrane contraction, and vitreoretinal traction. Thus, early intervention targeting hyalocytes could potentially mitigate disease progression and prevent the development of proliferative vitreoretinal disorders altogether, by eliminating the involvement of vitreous and hyalocytes.

[Vitreous body in the treatment of exudative age-related macular degeneration : The medium is the message]. / Glaskörper bei der Therapie der exsudativen altersabhängigen Makuladegeneration : Das Medium ist die Message.

BACKGROUND: Intravitreal anti-vascular endothelial growth factor (VEGF) is the standard treatment for exudative age-related macular degeneration (AMD). The constitution of the vitreomacular interface varies greatly in cases of attached (with or without traction) or detached vitreous body, which can impact the effectiveness of the anti-VEGF treatment. OBJECTIVE: Based on the current literature this article displays the current state of the science on whether the constitution of the vitreous body has an effect on the anti-VEGF treatment. MATERIAL AND METHODS: The published data extracted from current trials and post hoc analyses concerning this topic are presented and put into the clinical context. RESULTS: The presence of a vitreomacular adhesion reduces the efficacy of anti-VEGF treatment of exudative AMD. Posterior vitreous body detachment represents a positive prognostic factor concerning the efficacy of anti-VEGF treatment but not necessarily the prognosis for visual acuity. CONCLUSION: Patients with attached vitreous body need a more intensive treatment monitoring compared to patients with detached vitreous body. Therefore, in eyes with initial posterior vitreous body detachment receiving a treat and extend regimen, the interval between anti-VEGF injections can be extended to 4 instead of 2 weeks without endangering the success of treatment.

[Role of vitreous in the pathogenesis of neovascular age-related macular degeneration]. / Die Rolle des Glaskörpers in der Pathogenese der exsudativen altersabhängigen Makuladegeneration.

Age-related changes in vitreous molecular and anatomic morphology begin early in life and involve two major processes: vitreous liquefaction and weakening of vitreo-retinal adhesion. An imbalance in these two processes results in anomalous posterior vitreous detachment (PVD), which comprises, among other conditions, vitreo-macular adhesion (VMA) and traction (VMT). VMA is more common in patients with neovascular age-related macular degeneration (nAMD) than age-matched control patients, with the site of posterior vitreous adherence to the inner retina correlating with location of neovascular complexes. The pernicious effects of an attached posterior vitreous on age-related macular degeneration (AMD) progression involve mechanical forces, enhanced fluid influx and inflammation in and between the retinal layers, hypoxia leading to an accumulation of vascular endothelial growth factor (VEGF) and other stimulatory cytokines, and probably an infiltration of hyalocytes. It has been shown that vitrectomy not only mitigates progression to end-stage AMD, but existing choroidal neovascularization regresses after surgery. Thus, surgical PVD induction during vitrectomy or by pharmacologic vitreolysis may be considered in non-responders to anti-VEGF treatment with concomitant VMA.

[Vitreoretinal surgery in age-related macular degeneration]. / Vitreoretinale Chirurgie bei altersabhängiger Makuladegeneration.

The structure of the vitreous body, its interaction with the retinal surface and tractive alterations of the vitreoretinal interface may play a role in the pathogenesis and the development of age-related macular degeneration (AMD). From clinical trials it can be concluded that posterior vitreous detachment (PVD) or vitreous removal may protect against the development of neovascular AMD. Vitreomacular adhesions may promote neovascular AMD and may have an impact on the efficacy and frequency of intravitreal vascular endothelial growth factor (VEGF) inhibition. Therefore, vitreomacular surgery may be considered as a treatment option in selected cases. Peeling of epimacular membranes and the internal limiting membrane (ILM) may contribute to stabilizing visual acuity and reducing the treatment burden of current intravitreal pharmacotherapy. At present, surgical interventions in AMD are mainly performed in cases of submacular hemorrhage involving the fovea. The treatment is not standardized and consists of liquefaction of the blood using recombinant tissue plasminogen activator (rTPA) and its pneumatic displacement, potentially combined with VEGF inhibition. Other submacular surgical strategies, such as choroidal neovascularization (CNV) extraction, macular translocation or transplantation of retinal pigment epithelium (RPE) are currently limited to selected cases as a salvage treatment; however, the development of these submacular surgical interventions has formed the basis for new approaches in the treatment of dry and neovascular AMD including submacular or intravitreal gene and stem cell therapy.

Single-Cell Protein and Transcriptional Characterization of Epiretinal Membranes From Patients With Proliferative Vitreoretinopathy.

Purpose: Proliferative vitreoretinopathy (PVR) remains an unresolved clinical challenge and can lead to frequent revision surgery and blindness vision loss. The aim of this study was to characterize the microenvironment of epiretinal PVR tissue, in order to shed more light on the complex pathophysiology and to unravel new treatment options. Methods: A total of 44 tissue samples were analyzed in this study, including 19 epiretinal PVRs, 13 epiretinal membranes (ERMs) from patients with macular pucker, as well as 12 internal limiting membranes (ILMs). The cellular and molecular microenvironment was assessed by cell type deconvolution analysis (xCell), RNA sequencing data and single-cell imaging mass cytometry. Candidate drugs for PVR treatment were identified in silico via a transcriptome-based drug-repurposing approach. Results: RNA sequencing of tissue samples demonstrated distinct transcriptional profiles of PVR, ERM, and ILM samples. Differential gene expression analysis revealed 3194 upregulated genes in PVR compared with ILM, including FN1 and SPARC, which contribute to biological processes, such as extracellular matrix (ECM) organization. The xCell and IMC analyses showed that PVR membranes were composed of macrophages, retinal pigment epithelium, and α-SMA-positive myofibroblasts, the latter predominantly characterized by the co-expression of immune cell signature markers. Finally, 13 drugs were identified as potential therapeutics for PVR, including aminocaproic acid and various topoisomerase-2A inhibitors. Conclusions: Epiretinal PVR membranes exhibit a unique and complex transcriptional and cellular profile dominated by immune cells and myofibroblasts, as well as a variety of ECM components. Our findings provide new insights into the pathophysiology of PVR and suggest potential targeted therapeutic options.

Transcriptional and Distributional Profiling of Microglia in Retinal Angiomatous Proliferation.

Macular neovascularization type 3, formerly known as retinal angiomatous proliferation (RAP), is a hallmark of age-related macular degeneration and is associated with an accumulation of myeloid cells, such as microglia (MG) and infiltrating blood-derived macrophages (MAC). However, the contribution of MG and MAC to the myeloid cell pool at RAP sites and their exact functions remain unknown. In this study, we combined a microglia-specific reporter mouse line with a mouse model for RAP to identify the contribution of MG and MAC to myeloid cell accumulation at RAP and determined the transcriptional profile of MG using RNA sequencing. We found that MG are the most abundant myeloid cell population around RAP, whereas MAC are rarely, if ever, associated with late stages of RAP. RNA sequencing of RAP-associated MG showed that differentially expressed genes mainly contribute to immune-associated processes, including chemotaxis and migration in early RAP and proliferative capacity in late RAP, which was confirmed by immunohistochemistry. Interestingly, MG upregulated only a few angiomodulatory factors, suggesting a rather low angiogenic potential. In summary, we showed that MG are the dominant myeloid cell population at RAP sites. Moreover, MG significantly altered their transcriptional profile during RAP formation, activating immune-associated processes and exhibiting enhanced proliferation, however, without showing substantial upregulation of angiomodulatory factors.

The Human Eye Transcriptome Atlas: A searchable comparative transcriptome database for healthy and diseased human eye tissue.

The applications of deep sequencing technologies in life science research and clinical diagnostics have increased rapidly over the last decade. Although fast algorithms for data processing exist, intuitive, portable solutions for data analysis are still rare. For this purpose, we developed a web-based transcriptome database, which provides a platform-independent, intuitive solution to easily explore and compare ocular gene expression of 100 diseased and healthy human tissue samples from 15 different tissue types collected at the Eye Center of the University of Freiburg. To ensure comparability of expression between different tissues, reads were normalized across all 100 samples. Differentially expressed genes were calculated between each tissue type to determine tissue-specific genes. Unsupervised analysis of all 100 samples revealed an accurate clustering according to different tissue types and a high tissue specificity by analyzing known tissue-specific marker genes. Bioinformatic cell type deconvolution using xCell provided detailed insights into the cellular profiles of each tissue type. Several new tissue-specific marker genes were identified. These genes were involved in tissue- or disease-specific processes, such as myelination for the optic nerve, visual perception for retina, keratinocyte differentiation for conjunctival carcinoma, as well as endothelial cell migration for choroidal neovascularization membranes. The results are accessible at the Human Eye Transcriptome Atlas website at https://www.eye-transcriptome.com. In summary, this searchable transcriptome database enables easy exploration of ocular gene expression in healthy and diseased human ocular tissues without bioinformatics expertise. Thus, it provides rapid access to detailed insights into the molecular mechanisms of various ocular tissues and diseases, as well as the rapid retrieval of potential new diagnostic and therapeutic targets.

Comparative transcriptome analysis of human and murine choroidal neovascularization identifies fibroblast growth factor inducible-14 as phylogenetically conserved mediator of neovascular age-related macular degeneration.

BACKGROUND: Visual outcome of patients with neovascular age-related macular degeneration has significantly improved during the last years following the introduction of anti-vascular endothelial growth factor (VEGF) therapy. However, about one third of patients show persistent exudation and decreasing visual acuity despite recurrent anti-VEGF treatment, which implies a role of other, still unknown proangiogenic mediators. METHODS: The present study applied transcriptional profiling of human and mouse (C57BL/6J wildtype) choroidal neovascularization (CNV) membranes each with reference to healthy control tissue to identify yet unrecognized mediators of CNV formation. Key factors were further investigated by immunohistochemistry as well as by intravitreal inhibition experiments and multiplex protein assays in the laser-induced CNV mouse model. FINDINGS: Transcriptional profiles of CNV membranes were characterized by enhanced activation of blood vessel development, cytoskeletal organization, and cytokine production, with angiogenesis and wound healing processes predominating in humans and activation of immune processes in mice. Besides several species-specific factors, 95 phylogenetically conserved CNV-associated genes were detected, among which fibroblast growth factor inducible-14 (FN14), a member of the tumor necrosis factor (TNF) receptor family, was identified as a key player of CNV formation. Blocking the pathway by intravitreal injection of a FN14 decoy receptor modulated the cytokine profile - most notably IL-6 - and led to a significant reduction of CNV size in vivo. INTERPRETATION: This study characterizes the transcriptome of human and mouse CNV membranes in an unprejudiced manner and identifies FN14 as a phylogenetically conserved mediator of CNV formation and a promising new therapeutic target for neovascular AMD. FUNDING: This study was funded by the Helmut Ecker Foundation and the Volker Homann Foundation.

Subretinal fibrosis in neovascular age-related macular degeneration: current concepts, therapeutic avenues, and future perspectives.

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the human retina which in its most aggressive form is associated with the formation of macular neovascularization (MNV) and subretinal fibrosis leading to irreversible blindness. MNVs contain blood vessels as well as infiltrating immune cells, myofibroblasts, and excessive amounts of extracellular matrix proteins such as collagens, fibronectin, and laminin which disrupts retinal function and triggers neurodegeneration. In the mammalian retina, damaged neurons cannot be replaced by tissue regeneration, and subretinal MNV and fibrosis persist and thus fuel degeneration and visual loss. This review provides an overview of subretinal fibrosis in neovascular AMD, by summarizing its clinical manifestations, exploring the current understanding of the underlying cellular and molecular mechanisms and discussing potential therapeutic approaches to inhibit subretinal fibrosis in the future.

Imaging mass cytometry for high-dimensional tissue profiling in the eye.

BACKGROUND: Imaging mass cytometry (IMC) combines the principles of flow cytometry and mass spectrometry (MS) with laser scanning spatial resolution and offers unique advantages for the analysis of tissue samples in unprecedented detail. In contrast to conventional immunohistochemistry, which is limited in its application by the number of possible fluorochrome combinations, IMC uses isoptope-coupled antibodies that allow multiplex analysis of up to 40 markers in the same tissue section simultaneously. METHODS: In this report we use IMC to analyze formalin-fixed, paraffin-embedded conjunctival tissue. We performed a 18-biomarkers IMC analysis of conjunctival tissue to determine and summarize the possibilities, relevance and limitations of IMC for deciphering the biology and pathology of ocular diseases. RESULTS: Without modifying the manufacturer's protocol, we observed positive and plausible staining for 12 of 18 biomarkers. Subsequent bioinformatical single-cell analysis and phenograph clustering identified 24 different cellular clusters with distinct expression profiles with respect to the markers used. CONCLUSIONS: IMC enables highly multiplexed imaging of ocular samples at subcellular resolution. IMC is an innovative and feasible method, providing new insights into ocular disease pathogenesis that will be valuable for basic research, drug discovery and clinical diagnostics.

Transcriptional Profiling Identifies Upregulation of Neuroprotective Pathways in Retinitis Pigmentosa.

Hereditary retinal degenerations like retinitis pigmentosa (RP) are among the leading causes of blindness in younger patients. To enable in vivo investigation of cellular and molecular mechanisms responsible for photoreceptor cell death and to allow testing of therapeutic strategies that could prevent retinal degeneration, animal models have been created. In this study, we deeply characterized the transcriptional profile of mice carrying the transgene rhodopsin V20G/P23H/P27L (VPP), which is a model for autosomal dominant RP. We examined the degree of photoreceptor degeneration and studied the impact of the VPP transgene-induced retinal degeneration on the transcriptome level of the retina using next generation RNA sequencing (RNASeq) analyses followed by weighted correlation network analysis (WGCNA). We furthermore identified cellular subpopulations responsible for some of the observed dysregulations using in situ hybridizations, immunofluorescence staining, and 3D reconstruction. Using RNASeq analysis, we identified 9256 dysregulated genes and six significantly associated gene modules in the subsequently performed WGCNA. Gene ontology enrichment showed, among others, dysregulation of genes involved in TGF-ß regulated extracellular matrix organization, the (ocular) immune system/response, and cellular homeostasis. Moreover, heatmaps confirmed clustering of significantly dysregulated genes coding for components of the TGF-ß, G-protein activated, and VEGF signaling pathway. 3D reconstructions of immunostained/in situ hybridized sections revealed retinal neurons and Müller cells as the major cellular population expressing representative components of these signaling pathways. The predominant effect of VPP-induced photoreceptor degeneration pointed towards induction of neuroinflammation and the upregulation of neuroprotective pathways like TGF-ß, G-protein activated, and VEGF signaling. Thus, modulation of these processes and signaling pathways might represent new therapeutic options to delay the degeneration of photoreceptors in diseases like RP.

Mapping the origin and fate of myeloid cells in distinct compartments of the eye by single-cell profiling.

Similar to the brain, the eye is considered an immune-privileged organ where tissue-resident macrophages provide the major immune cell constituents. However, little is known about spatially restricted macrophage subsets within different eye compartments with regard to their origin, function, and fate during health and disease. Here, we combined single-cell analysis, fate mapping, parabiosis, and computational modeling to comprehensively examine myeloid subsets in distinct parts of the eye during homeostasis. This approach allowed us to identify myeloid subsets displaying diverse transcriptional states. During choroidal neovascularization, a typical hallmark of neovascular age-related macular degeneration (AMD), we recognized disease-specific macrophage subpopulations with distinct molecular signatures. Our results highlight the heterogeneity of myeloid subsets and their dynamics in the eye that provide new insights into the innate immune system in this organ which may offer new therapeutic targets for ophthalmological diseases.

[Chronification of malignant glaucoma after cataract surgery]. / Chronifiziertes malignes Glaukom nach Kataraktoperation.

The occurrence of malignant glaucoma several years after cataract surgery is a very rare delayed complication. An increasing myopic shift can be an early hint for the formation. A surgical intervention is often inevitable; however, intraocular pressure can also be successfully managed with conservative treatment as in the case described. Therefore, treatment should be adapted to the situation and individually decided how invasive the treatment must be and whether a vitrectomy is absolutely necessary.

MACE RNA sequencing analysis of conjunctival squamous cell carcinoma and papilloma using formalin-fixed paraffin-embedded tumor tissue.

Recent advances in the field of biomedical research allow for elucidation of the transcriptional signature of rare tumors such as conjunctival squamous cell carcinoma (SCC). In this study we compare its expression profile to conjunctival papilloma (Pap) and healthy conjunctival tissue (Ctrl) and develop a classification tool to differentiate these entities. Seven conjunctival SCC, seven Pap and ten Ctrl were formalin-fixed and paraffin-embedded (FFPE) and analyzed using Massive Analysis of cDNA Ends (MACE) RNA sequencing. Differentially expressed genes (DEG) and gene ontology (GO) clusters were explored and the abundance of involved cell types was quantified by xCell. Finally, a classification model was developed to distinguish SCC from Pap and Ctrl. Among the most prominent DEG in SCC a plethora of keratins were upregulated when compared to Pap and Ctrl. xCell analysis revealed an enrichment of immune cells, including activated dendritic cells and T-helper type 1 cells (Th1), in SCC when compared to Ctrl. The generated classification model could reliably discriminate between the three entities according to the expression pattern of 30 factors. This study provides a transcriptome-wide gene expression profile of rare conjunctival SCC. The analysis identifies distinct keratins, as well as dendritic and Th1 cells as important mediators in SCC. Finally, the provided gene expression classifier may become an aid to the conventional histological classification of conjunctival tumors in uncertain cases.

Corneal tissue induces transcription of metallothioneins in monocyte-derived human macrophages.

PURPOSE: Immune reactions following corneal transplantation are the most common cause of transplant failure. However, the underlying mechanisms of corneal graft rejection are not yet fully understood but increasing evidence points to a crucial role of the innate immune system in this context. Using a human in vitro model, we aimed to assess the response of human macrophages to stimulation with human corneal tissue and whether corneal endothelial cells (CEC) have immune-modulating properties. METHODS: Human monocytes were isolated from peripheral blood mononuclear cells and differentiated into monocyte-derived macrophages (MDM). A standardized protocol was used for disaggregation of human corneas into fragments of defined sizes. MDMs were stimulated using processed corneal material with or without CEC. Lipopolysaccharide (LPS) or interferon-gamma (IFNγ) served as controls. RNA sequencing was applied to analyze the impact of differential stimulation of MDMs on their transcriptional profile. RNA sequencing results were validated using digital PCR. RESULTS: The transcriptional profile of MDMs was significantly modulated by the type of stimulus used for MDM activation as well as by the individual MDM donor. LPS- or IFNγ-stimulation resulted in distinct transcriptional alterations compared to unstimulated MDMs including an upregulation of various cytokines such as CCL3, 4, 5, 19 or CXCL9. Corneal tissue induced the differential expression of 45 genes when compared to unstimulated MDMs, with several metallothioneins (MTs) among the upregulated factors (MT1A, MT1E, MT1F, MT1G, MT1H, MT1L, MT1M, MT1X, MT2A). This effect was independent of the presence or absence of CEC. PCR validation confirmed induction of 3 different metallothioneins (MT1G, MT1H and MT2A) in MDMs stimulated by corneal tissue. CONCLUSIONS: The MDM in vitro model proved to be a robust tool to study the effects of LPS, IFNγ and corneal tissue homogenates on the transcriptional activity of MDM. Human macrophages showed a distinct upregulation of various MTs when challenged with human corneal allogen with or without corneal endothelium, which might have an immune-modulatory effect. As a general observation, it appears that in MDM-based studies a significant donor-dependent effect on the transcriptional profile of MDMs needs to be considered and adjusted before downstream analysis.

Transcriptional Profiling Uncovers Human Hyalocytes as a Unique Innate Immune Cell Population.

Purpose: To decipher the transcriptional signature of macrophages of the human vitreous, also known as hyalocytes, and compare it to the profiles of other myeloid cell populations including human blood-derived monocytes, macrophages, and brain microglia. Methods: This study involves a total of 13 patients of advanced age with disorders of the vitreoretinal interface undergoing vitrectomy at the University Eye Hospital Freiburg between 2018 and 2019. Vitreal hyalocytes were analyzed by fluorescence-activated cell sorting (FACS) and isolated as CD45+CD11b+CX3CR1+Mat-Mac+ cells using a FACS-based sorting protocol. RNA extraction, library preparation and RNA sequencing were performed and the sequencing data was analyzed using the Galaxy web platform. The transcriptome of human hyalocytes was compared to the transcriptional profile of human blood-derived monocytes, macrophages and brain microglia obtained from public databases. Protein validation for selected factors was performed by immunohistochemistry on paraffin sections from three human donor eyes. Results: On average, 383 ± 233 hyalocytes were isolated per patient, resulting in 128 pg/µl ± 76 pg/µl total RNA per sample. RNA sequencing revealed that SPP1, FTL, CD74, and HLA-DRA are among the most abundantly expressed genes in hyalocytes, which was confirmed by immunofluorescence for CD74, FTL, and HLA-DRA. Gene ontology (GO) enrichment analysis showed that biological processes such as "humoral immune response," "leukocyte migration," and "antigen processing and presentation of peptide antigen" (adjusted p < 0.001) are dominating in vitreal hyalocytes. While the comparison of the gene expression profiles of hyalocytes and other myeloid cell populations showed an overall strong similarity (R2 > 0.637, p < 0.001), hyalocytes demonstrated significant differences with respect to common leukocyte-associated factors. In particular, transcripts involved in the immune privilege of the eye, such as POMC, CD46, and CD86, were significantly increased in hyalocytes compared to other myeloid cell subsets. Conclusion: Human hyalocytes represent a unique and distinct innate immune cell population specialized and adapted for the tissue-specific needs in the human vitreous. Vitreal hyalocytes are characterized by a strong expression of genes related to antigen processing and presentation as well as immune modulation. Thus, hyalocytes may represent an underestimated mediator in vitreoretinal disease and for the immune privilege of the eye.

Transcriptional characterization of conjunctival melanoma identifies the cellular tumor microenvironment and prognostic gene signatures.

This study characterizes the transcriptome and the cellular tumor microenvironment (TME) of conjunctival melanoma (CM) and identifies prognostically relevant biomarkers. 12 formalin-fixed and paraffin-embedded CM were analyzed by MACE RNA sequencing, including six cases each with good or poor clinical outcome, the latter being defined by local recurrence and/or systemic metastases. Eight healthy conjunctival specimens served as controls. The TME of CM, as determined by bioinformatic cell type enrichment analysis, was characterized by the enrichment of melanocytes, pericytes and especially various immune cell types, such as plasmacytoid dendritic cells, natural killer T cells, B cells and mast cells. Differentially expressed genes between CM and control were mainly involved in inhibition of apoptosis, proteolysis and response to growth factors. POU3F3, BIRC5 and 7 were among the top expressed genes associated with inhibition of apoptosis. 20 genes, among them CENPK, INHA, USP33, CASP3, SNORA73B, AAR2, SNRNP48 and GPN1, were identified as prognostically relevant factors reaching high classification accuracy (area under the curve: 1.0). The present study provides new insights into the TME and the transcriptional profile of CM and additionally identifies new prognostic biomarkers. These results add new diagnostic tools and may lead to new options of targeted therapy for CM.

RNA Sequencing of Formalin-Fixed and Paraffin-Embedded Tissue as a Complementary Method in Ophthalmopathology. / Die RNA-Sequenzierung von formalinfixiertem und in Paraffin eingebettetem Gewebe als ergänzende Methode der Ophthalmopathologie.

The high-throughput method of "Next Generation Sequencing" (NGS) allows cost-effective decoding of the nucleotide sequences of millions of RNA molecules in a sample. This makes it possible to determine the number of distinct RNA molecules in tissues or cells and to use these data to draw conclusions. The entirety of RNAs, in particular mRNAs (messenger RNAs) as potential precursors of proteins, provides a comprehensive insight into the functional state of the cells and tissues under investigation. In addition to cell cultures or unfixed tissue, formalin-fixed and paraffin-embedded (FFPE) tissue can also be analysed for this purpose using specific methods. In this overview, the methodological strategy and its application to the field of ophthalmic histopathology are presented.