Biology subjects

Grosche, A.

Publications and source records attributed to Grosche, A..

4 recordsLinked to original sources

bioRxiv2023

The glucocorticoid receptor as a master regulator of Müller cell gliosis in the diabetic retina

Diabetic retinopathy (DR) is considered a primarily microvascular complication of diabetes. Muller glia cells are at the center of the retinal neurovascular unit and play a critical role in DR. We therefore investigated Muller cell-specific signaling pathways that are altered in DR to identify novel targets for gene therapy. Using a multi-omics approach on purified Muller cells from diabetic db/db mice, we found the mRNA and protein expression of the glucocorticoid receptor (GR) to be significantly decreased, while its target gene cluster was down-regulated. Further, oPOSSUM TF analysis and ATAC-sequencing identified the GR as a master regulator of Muller cell gliosis in DR. Cortisol not only increased GR phosphorylation. It also induced changes in the expression of known GR target genes in retinal explants. Finally, retinal functionality was improved by AAV-mediated overexpression of GR in Muller cells. Our study demonstrates an important role of the glial GR in DR and implies that therapeutic approaches targeting this signalling pathway should be aimed at increasing GR expression rather than the addition of more ligand. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/556478v2_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@c7869forg.highwire.dtl.DTLVardef@1574edforg.highwire.dtl.DTLVardef@fb1329org.highwire.dtl.DTLVardef@1a6ee60_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Release of VAMP5-positive extracellular vesicles from specialized domains of retinal Müller cells in vivo

Cell-cell interactions in the central nervous system are based on the release of molecules mediating signal exchange and providing structural and trophic support through vesicular exocytosis and the formation of extracellular vesicles. The specific mechanisms employed by each cell type in the brain are incompletely understood. Here, we explored the means of communication used by Muller cells, a type of radial glial cells in the retina, which forms part of the central nervous system. Using immunohistochemical, electron microscopic, and molecular analyses, we provide evidence for the release of distinct extracellular vesicles from endfeet and microvilli of retinal Muller cells in adult mice in vivo. We identify VAMP5 as a Muller cell-specific SNARE component that is part of extracellular vesicles and responsive to ischemia, and we reveal differences between the secretomes of immunoaffinity-purified Muller cells and neurons in vitro. Our findings suggest extracellular vesicle-based communication as an important mediator of cellular interactions in the retina.

neuroscience↗

bioRxiv2021

Proteomic phenotyping of stimulated Mueller cells uncovers profound pro-inflammatory signaling and antigen-presenting capacity

Muller cells are the main macroglial cells of the retina exerting a wealth of functions to maintain retinal homoeostasis. Upon pathological changes in the retina, they become gliotic with both protective and detrimental consequences. Accumulating data also provide evidence for a pivotal role of Muller cells in the pathogenesis of diabetic retinopathy (DR). While microglial cells, the resident immune cells of the retina are considered as main players in inflammatory processes associated with DR, the implication of activated Muller cells in chronic retinal inflammation remains to be elucidated. In order to assess the signaling capacity of Muller cells and their role in retinal inflammation, we performed in-depth proteomic analysis of Muller cell proteomes and secretomes after stimulation with INF{gamma}, TNF, IL-4, IL-6, IL-10, VEGF, TGF{beta}1, TGF{beta}2 and TGF{beta}3. We used both, primary porcine Muller cells and the human Muller cell line MIO-M1 for our hypothesis generating approach. Our results point towards an intense signaling capacity of Muller cells, which reacted in a highly discriminating manner upon treatment with different cytokines. Stimulation of Muller cells resulted in a primarily pro-inflammatory phenotype with secretion of cytokines and components of the complement system. Furthermore, we observed evidence for mitochondrial dysfunction, implying oxidative stress after treatment with the various cytokines. Finally, both MIO-M1 cells and primary porcine Muller cells showed several characteristics of atypical antigen-presenting cells, as they are capable of inducing MHC class I and MHC class II with co-stimulatory molecules. In line with this, they express proteins associated with formation and maturation of phagosomes. Thus, our findings underline the importance of Muller cell signaling in the inflamed retina, indicating an active role in chronic retinal inflammation underlying the pathogenesis of diabetic retinopathy.

immunology↗

bioRxiv2018

Cell type-specific complement expression from healthy and diseased retinae

Retinal degeneration is associated with complement system activation, but retinal sources of complement are unknown. Here, we describe the human and murine complement transcriptomes of Muller cells, microglia/macrophages, vascular cells, neurons and retinal pigment epithelium (RPE) in health and disease. All cell populations expressed c1s, c3, cfb, cfp, cfh and cfi. Murine Muller cells contributed the highest amount of complement activators (c1s, c3, cfb). RPE mainly expressed cfh, while cfi and cfp transcripts were most abundant in neurons. The main complement negative regulator in the human retina was cfi, while cfh dominated in the murine retina. Importantly, the expression of c1s, cfb, cfp, cfi increased and that of cfh decreased with aging. Impaired photoreceptor recycling led to an enhanced c3 expression in RPE and to a reduced cfi expression in microglia/macrophages. Expression of complement components was massively upregulated after transient retinal ischemia in murine microglia, Muller cells and RPE. The individual signature of complement expression in distinct murine and human retinal cell types indicates a local, well-orchestrated regulation of the complement system in both species.

neuroscience↗