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Project description:The resident astrocytes-retinal ganglion cell lipoxin circuit is impaired during retinal stress that include exocytotoxic- and ocular hypertension-induced neuropathy. Two endogenous lipoxins (Lipoxin A4 and Lipoxin B4) produced by homeostatic astrocytes directly act on RGCs. LXB4 is the most potent lipoxin in the retina and directly increases RGC survival and function in ocular hypertension-induced neuropathy. Homeostatic roles and cellular targets of LXB4 in the retina and optic nerve are a critical gap in knowledge. Single-cell RNA sequencing was used to define cellular targets and signaling of LXB4 in the retina. For modeling neurodegeneration, sustained ocular hypertension was induced by silicone-oil injection in the anterior chamber of mouse eyes. For morphological characterization of microglia populations in the retina and optic nerve, we used MorphOMICs and pseudotime trajectory analysis. Bulk RNA sequencing of optic nerves was performed to characterize pathways and mechanism of action for LXB4. qPCR and immunohistochemistry were used for validation of transcriptomics data. Student’s t-test and one-way ANOVA were used to determine differences between experimental groups. Single Cell transcriptomic identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglia function uncovered that ocular hypertension induces distinct, temporally defined and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia (DAM) in the brain, was only induced in a unique population of optic nerve microglia but not the retina. Genetic deletion of lipoxin formation correlated with presence of a CD74 optic nerve microglia population in normotensive eyes optic, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-PI3K (p-PI3K) expression levels in the optic nerve, that was reduced by LXB4 treatment. Results identify distal optic nerve microglial dynamic and reactive responses as a key feature of ocular hypertension induce neurodegeneration. Our findings establish microglia regulation as a new LXB4 cell target in the retina and optic nerve. LXB4 maintenance of optic nerve microglia homeostatic phenotype and inhibition of a disease-associated phenotype are potential mechanisms for LXB4 neuroprotection.
2024-04-10 | GSE251716 | GEO
Project description:The resident astrocytes-retinal ganglion cell lipoxin circuit is impaired during retinal stress that include exocytotoxic- and ocular hypertension-induced neuropathy. Two endogenous lipoxins (Lipoxin A4 and Lipoxin B4) produced by homeostatic astrocytes directly act on RGCs. LXB4 is the most potent lipoxin in the retina and directly increases RGC survival and function in ocular hypertension-induced neuropathy. Homeostatic roles and cellular targets of LXB4 in the retina and optic nerve are a critical gap in knowledge. Single-cell RNA sequencing was used to define cellular targets and signaling of LXB4 in the retina. For modeling neurodegeneration, sustained ocular hypertension was induced by silicone-oil injection in the anterior chamber of mouse eyes. For morphological characterization of microglia populations in the retina and optic nerve, we used MorphOMICs and pseudotime trajectory analysis. Bulk RNA sequencing of optic nerves was performed to characterize pathways and mechanism of action for LXB4. qPCR and immunohistochemistry were used for validation of transcriptomics data. Student’s t-test and one-way ANOVA were used to determine differences between experimental groups. Single Cell transcriptomic identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglia function uncovered that ocular hypertension induces distinct, temporally defined and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia (DAM) in the brain, was only induced in a unique population of optic nerve microglia but not the retina. Genetic deletion of lipoxin formation correlated with presence of a CD74 optic nerve microglia population in normotensive eyes optic, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-PI3K (p-PI3K) expression levels in the optic nerve, that was reduced by LXB4 treatment. Results identify distal optic nerve microglial dynamic and reactive responses as a key feature of ocular hypertension induce neurodegeneration. Our findings establish microglia regulation as a new LXB4 cell target in the retina and optic nerve. LXB4 maintenance of optic nerve microglia homeostatic phenotype and inhibition of a disease-associated phenotype are potential mechanisms for LXB4 neuroprotection.
2024-04-10 | GSE250615 | GEO
Project description:Glaucoma is the leading cause of irreversible vision loss. Ocular hypertension is a major risk factor for glaucoma and recent work has demonstrated critical early neuroinflammatory insults occur in the optic nerve head following ocular hypertension. Microglia and infiltrating monocytes are likely candidates to drive these neuroinflammatory insults. However, the exact molecular identity / transcriptomic profile of microglia following ocular hypertensive insults is unknown. To elucidate the molecular identity of microglia after long-term exposure to ocular hypertension, we used a mouse model of glaucoma (DBA/2?J). We performed RNA-sequencing of microglia mRNA from the optic nerve head at a time point following ocular hypertensive insults, but preceding detectable neurodegeneration (with microglia identified as being CD45lo/CD11b+/CD11c-). Furthermore, RNA-sequencing was performed on optic nerve head microglia from mice treated with radiation therapy, a potent therapy preventing neuroinflammatory insults. Transcriptomic profiling of optic nerve head microglia mRNA identifies metabolic priming with marked changes in mitochondrial gene expression, and changes to phagocytosis, inflammatory, and sensome pathways. The data predict that many functions of microglia that help maintain tissue homeostasis are affected. Comparative analysis of these data with data from previously published whole optic nerve head tissue or monocyte-only samples from DBA/2?J mice demonstrate that many of the neuroinflammatory signatures in these data sets arise from infiltrating monocytes and not reactive microglia. Finally, our data demonstrate that prophylactic radiation therapy of DBA/2?J mice potently abolishes these microglia metabolic transcriptomic changes at the same time points. Together, our data provide a unique resource for the community to help drive further hypothesis generation and testing in glaucoma.
| S-EPMC7249412 | biostudies-literature
Project description:Purpose: The optic nerve head (ONH) is the likely site of initial damage in the glaucomatous eye. Despite the recognition of elevated intraocular pressure (IOP) as a leading risk factor for the development of glaucoma, ocular hypertension (OHT) eyes displaying consistently elevated IOP do not experience ONH damage. This study aims to identify global gene expression variations in glaucomatous ONHs and their relationship to those identified in OHT derived ONHs in order to improve our understanding of IOP-induced ONH damage. Methods: (N=6) ONHs were collected from clinically confirmed glaucoma, OHT and age-matched control donor eyes. Total RNA extracted from ONHs was reverse transcribed and assayed using the Affymetrix Human Exon 1.0 ST array. Differentially expressed genes in glaucoma versus control and OHT derived ONHs were identified using an ANOVA analysis with a 1.25 fold change limit and P-value < 0.05. Quantitative RT-PCR was performed to validate selected differentially expressed genes. Results: Microarray analysis revealed 149 under under-expressed genes in POAG versus control ONHs, many of which are involved in ion transport, axonogenesis and macromolecule catabolic processes. 297 genes were over expressed in OHT versus glaucoma derived ONHs. Mediators of oxidation-reduction and chemical homeostasis were among the most prominent gene groups identified. The over expression of prostaglandin-endoperoxide synthase 2, integrin, beta-like 1 and fibulin 5 in glaucomatous ONHs was confirmed by qRT-PCR. Conclusions: Our data demonstrates marked alteration in global gene expression patterns in the glaucomatous ONH, likely due to extensive tissue injury. The observed overlapping of several differentially expressed genes in glaucoma and OHT derived ONHs suggests the induction of common mechanisms in response to elevated IOP. Preferential over-expression of certain gene groups in OHT but not glaucoma derived ONHs may confer possible protection against IOP-induced ONH damage, which remains to be investigated in future studies. (N=6) Glaucoma, ocular hypertension and age-matched control ONHs were assayed to investigate and compare global gene expression patterns in each sample group.
2013-09-27 | E-GEOD-45570 | biostudies-arrayexpress
Project description:Purpose: The optic nerve head (ONH) is the likely site of initial damage in the glaucomatous eye. Despite the recognition of elevated intraocular pressure (IOP) as a leading risk factor for the development of glaucoma, ocular hypertension (OHT) eyes displaying consistently elevated IOP do not experience ONH damage. This study aims to identify global gene expression variations in glaucomatous ONHs and their relationship to those identified in OHT derived ONHs in order to improve our understanding of IOP-induced ONH damage. Methods: (N=6) ONHs were collected from clinically confirmed glaucoma, OHT and age-matched control donor eyes. Total RNA extracted from ONHs was reverse transcribed and assayed using the Affymetrix Human Exon 1.0 ST array. Differentially expressed genes in glaucoma versus control and OHT derived ONHs were identified using an ANOVA analysis with a 1.25 fold change limit and P-value < 0.05. Quantitative RT-PCR was performed to validate selected differentially expressed genes. Results: Microarray analysis revealed 149 under under-expressed genes in POAG versus control ONHs, many of which are involved in ion transport, axonogenesis and macromolecule catabolic processes. 297 genes were over expressed in OHT versus glaucoma derived ONHs. Mediators of oxidation-reduction and chemical homeostasis were among the most prominent gene groups identified. The over expression of prostaglandin-endoperoxide synthase 2, integrin, beta-like 1 and fibulin 5 in glaucomatous ONHs was confirmed by qRT-PCR. Conclusions: Our data demonstrates marked alteration in global gene expression patterns in the glaucomatous ONH, likely due to extensive tissue injury. The observed overlapping of several differentially expressed genes in glaucoma and OHT derived ONHs suggests the induction of common mechanisms in response to elevated IOP. Preferential over-expression of certain gene groups in OHT but not glaucoma derived ONHs may confer possible protection against IOP-induced ONH damage, which remains to be investigated in future studies.
2013-09-27 | GSE45570 | GEO
Project description:The nonhuman primate model of glaucomatous optic neuropathy most faithfully reproduces the human disease. We used high-density oligonucleotide arrays to investigate whole genome transcriptional changes occurring at the optic nerve head during primate experimental glaucoma.Laser scarification of the trabecular meshwork of cynomolgus macaques produced elevated intraocular pressure that was monitored over time and led to varying degrees of damage in different samples. The macaques were examined clinically before enucleation and the myelinated optic nerves were processed post-mortem to determine the degree of neuronal loss. Global gene expression was examined in dissected optic nerve heads with Affymetrix GeneChip microarrays. We validated a subset of differentially expressed genes using qRT-PCR, immunohistochemistry, and immuno-enriched astrocytes from healthy and glaucomatous human donors. These genes have previously defined roles in axonal outgrowth, immune response, cell motility, neuroprotection, and extracellular matrix remodeling.Our findings show that glaucoma is associated with increased expression of genes that mediate axonal outgrowth, immune response, cell motility, neuroprotection, and ECM remodeling. These studies also reveal that, as glaucoma progresses, retinal ganglion cell axons may make a regenerative attempt to restore lost nerve cell contact.
| S-EPMC2567987 | biostudies-literature
Project description:Glaucoma leads to vision loss due to retinal ganglion cell death. Astrocyte reactivity contributes to neurodegeneration. Our recent study found that lipoxin B4 (LXB4), produced by retinal astrocytes, has direct neuroprotective actions on retinal ganglion cells. In this study, we aimed to investigate how the autacoid LXB4 influences astrocyte reactivity in the retina under inflammatory cytokine-induced activation and ocular hypertension conditions. The protective activity of LXB4 was investigatedin vivousing the mouse silicone-oil model of chronic ocular hypertension (n=40). By employing a range of analytical techniques, including bulk RNA-seq, RNAscope in-situhybridization, qPCR, and lipidomic analyses, we discovered the formation of neuroprotective lipoxins in rodents (including the retina and optic nerve), primates (optic nerve), and human brain astrocytes, indicating their presence across various species. Our findings in the mouse retina demonstrated significant dysregulation of the lipoxin pathway in response to chronic ocular hypertension, leading to an increase in 5-lipoxygenase (5-LOX) activity and a decrease in 15-lipoxygenase activity. This dysregulation was coincident with a marked upregulation of astrocyte reactivity. Reactive human brain astrocytes also showed a significant increase in 5-LOX. Administration of LXB4 regulated the lipoxin pathway, restored and amplified LXA4 generation (another lipoxin with distinct bioactions), and mitigated astrocyte reactivity in mouse retinas and human brain astrocytes. In conclusion, the lipoxin pathway is functionally expressed in rodents, primates, and human astrocytes, and is a resident neuroprotective pathway that is downregulated in reactive astrocytes. Novel cellular targets for LXB4’s neuroprotective action are inhibition of astrocyte reactivity and restoration of lipoxin generation. Amplifying the lipoxin pathway is a potential target to disrupt or prevent astrocyte reactivity in neurodegenerative diseases.
2024-04-10 | GSE241131 | GEO
Project description:FGF signaling plays a pivotal role in eye development. Previous studies using in vitro chick models and systemic zebrafish mutants have suggested that FGF signaling is required for the patterning and specification of the optic vesicle, but due to a lack of genetic models, its role in mammalian retinal development remains elusive. In this study, we show that specific deletion of Fgfr1 and Fgfr2 in the optic vesicle disrupts ERK signaling, which results in optic disc and nerve dysgenesis and, ultimately, ocular coloboma. Defective FGF signaling does not abrogate Shh or BMP signaling, nor does it affect axial patterning of the optic vesicle. Instead, FGF signaling regulates Mitf and Pax2 in coordinating the closure of the optic fissure and optic disc specification, which is necessary for the outgrowth of the optic nerve. Genetic evidence further supports that the formation of an Frs2?-Shp2 complex and its recruitment to FGF receptors are crucial for downstream ERK signaling in this process, whereas constitutively active Ras signaling can rescue ocular coloboma in the FGF signaling mutants. Our results thus reveal a previously unappreciated role of FGF-Frs2?-Shp2-Ras-ERK signaling axis in preventing ocular coloboma. These findings suggest that components of FGF signaling pathway may be novel targets in the diagnosis of and the therapeutic interventions for congenital ocular anomalies.
| S-EPMC3678341 | biostudies-literature
Project description:PurposePrevious analyses of the DBA/2J mouse glaucoma model show a sectorial degeneration pattern suggestive of an optic nerve head insult. In addition, there are large numbers of retinal ganglion cells (RGCs) that cannot be retrogradely labeled but maintain RGC gene expression, and many of these have somatic phosphorylated neurofilament labeling. Here the authors further elucidate these features of glaucomatous degeneration in a rat ocular hypertension model.MethodsIOP was elevated in Wistar rats by translimbal laser photocoagulation. Retina whole mounts were analyzed for Sncg mRNA in situ hybridization, fluorogold (FG) retrograde labeling, and immunohistochemistry for phosphorylated neurofilaments (pNF) at 10 and 29 days after IOP increase. A novel automatic method was used to estimate axon numbers in plastic sections of optic nerves.ResultsSncg mRNA was confirmed as a specific marker for RGCs in rat. Loss of RGCs after IOP elevation occurred in sectorial patterns. Sectors amid degeneration contained RGCs that were likely disconnected because these had pNF in their somas and dendrites, were not labeled by FG, and were associated with reactive plasticity within the retina. Most of the axon loss within the optic nerve already occurred by 10 days after the onset of IOP elevation.ConclusionsThese data demonstrate that the pattern of RGC loss after laser-induced ocular hypertension in rats is similar to that previously reported in DBA/2J mice. The results support the view that in glaucoma RGC axons are damaged at the optic nerve head and degenerate within the optic nerve before there is loss of RGC somas.
| S-EPMC3053289 | biostudies-literature
Project description:In humans, the longitudinal characterisation of early optic nerve head (ONH) damage in ocular hypertension (OHT) is difficult as patients with glaucoma usually have structural ONH damage at the time of diagnosis. Previous studies assessed glaucomatous ONH cupping by measuring the anterior lamina cribrosa depth (LCD) and minimal rim width (MRW) using optical coherence tomography (OCT). In this study, we induced OHT by repeated intracameral microbead injections in 16 cynomolgus primates (10 unilateral; 6 bilateral) and assessed the structural changes of the ONH longitudinally to observe early changes. Elevated intraocular pressure (IOP) in OHT eyes was maintained for 7 months and serial OCT measurements were performed during this period. The mean IOP was significantly elevated in OHT eyes when compared to baseline and compared to the control eyes. Thinner MRW and deeper LCD values from baseline were observed in OHT eyes with the greatest changes seen between month 1 and month 2 of OHT. Both the mean and maximum IOP values were significant predictors of MRW and LCD changes, although the maximum IOP was a slightly better predictor. We believe that this model could be useful to study IOP-induced early ONH structural damage which is important for understanding glaucoma pathogenesis.
| S-EPMC7477239 | biostudies-literature