Project description:To explore whether IL-4 could exert a novel protective role for RPE damage and attenuate the pathogenesis of dry age-related macular degeneration (AMD), we established a retinal degeneration model of dry AMD by intravenous injection of NaIO3, and explored the treatment effects of intravitreal IL-4 injection. We found exogenous IL-4 protected against retinal degeneration characterized by well-preserved structures and improved retinal function. The RNA-seq analysis revealed that IL-4 treatment suppressed the essential oxidative and pro-inflammatory pathways in the degenerative retina. IL-4 induced the expression of IL-4Rα and Nrf2 for anti-oxidative defense in vivo and in vitro. Our data provides evidences that IL-4 can be a useful neuroprotective agent against retinal degeneration due to its antioxidant and anti-inflammatory property through Nrf2 activation. The IL-4/IL-4Rα-Nrf2 axis maybe the potential targets for the development of novel therapies for dry AMD.
Project description:In many forms of retinal degenerative diseases in human, microglia relocate to and accumulate in the subretinal space. However, the roles of microglia in retinal degeneration are poorly understood. By leveraging single cell RNA-seq, we identified a distinct microglia subtype in the subretinal space. These microglia underwent transcriptional reprogramming characterized by reduced expression of homeostatic checkpoint genes and upregulation of injury-responsive genes. Importantly, this transition is associated with protection of the retinal pigment epithelium from damage caused by disease. Therefore, our data demonstrated microglial heterogeneity in retinal degeneration and may provide important implications for developing new strategies to prevent loss of vision.
Project description:Progressive dysfunction and death of photoreceptors occurs in blinding diseases such as age-related macular degeneration and retinitis pigmentosa. The MyD88 protein is a central adaptor molecule for innate immune system Toll-like receptors (TLR) and interleukin-1 receptor (IL-1R), which are active in retinal disease and induce cytokine secretion from inflammatory cells. We recently demonstrated that inhibiting MyD88 in mouse models of retinal degeneration led to increased rod photoreceptor survival, which was associated with altered cytokine expression and increased neuroprotective microglia. However, additional molecular changes associated with MyD88 inhibitor-mediated neuroprotection are not known. Quantitative proteomics using iTRAQ LC-MS/MS is a high-throughput method ideal for providing new information about the molecular mechanisms contributing to photoreceptor protection. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) labeling followed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) for quantitative proteomic analysis on the rd10 mouse model of retinal degeneration to identify protein pathways changed by MyD88 inhibition. A total of 42 proteins were differentially expressed in retinas from mice treated with MyD88 inhibitor compared with control. Notably, increased expression of multiple crystallins and chaperones that respond to cellular stress and have anti-apoptotic properties were identified in the MyD88 inhibited mice. Additional differentially expressed biological processes included pyrophosphatase activity and peptide biosynthesis. These data suggest that inhibiting MyD88 may enhance chaperone-mediated tissue protective pathways. Therefore, this study provides new insight into molecular events that contribute to photoreceptor protection from modulating inflammation.
Project description:Molecular mechanisms underlying retinal degeneration are not well characterized including in the widely utilized Royal College of Surgeons (RCS) rat model of retinal degeneration. To better understand molecular pathways driving retinal degeneration we performed mRNA transcriptomics on RCS retinas following the natural progression of the disease. This data can identify novel therapeutic targets for future development.
Project description:We determined which metabolic pathways are activated by hypoxia-inducible factor 1-mediated (HIF-1-mediated) protection against oxygen-induced retinopathy (OIR) in newborn mice, the experimental correlate to retinopathy of prematurity, a leading cause of infant blindness. HIF-1 coordinates the change from oxidative to glycolytic metabolism and mediates flux through serine and 1-carbon metabolism (1CM) in hypoxic and cancer cells. We used untargeted metabolite profiling in vivo to demonstrate that hypoxia mimesis activates serine/1CM. Both [13C6] glucose labeling of metabolites in ex vivo retinal explants as well as in vivo [13C3] serine labeling of metabolites followed in liver lysates strongly suggest that retinal serine is primarily derived from hepatic glycolytic carbon and not from retinal glycolytic carbon in newborn pups. In HIF-1α2lox/2lox albumin-Cre-knockout mice, reduced or near-0 levels of serine/glycine further demonstrate the hepatic origin of retinal serine. Furthermore, inhibition of 1CM by methotrexate blocked HIF-mediated protection against OIR. This demonstrated that 1CM participates in protection induced by HIF-1 stabilization. The urea cycle also dominated pathway enrichment analyses of plasma samples. The dependence of retinal serine on hepatic HIF-1 and the upregulation of the urea cycle emphasize the importance of the liver to remote protection of the retina.
Project description:Age-related macular degeneration (AMD), featured with dysfunction and loss of retinal pigment epithelium (RPE), is lacking efficient therapeutic approaches. According to our previous studies, human amniotic epithelial stem cells (hAESCs) may serve as a potential seed cell source of RPE cells for therapy because they have no ethical concerns, no tumorigenicity, and little immunogenicity. Herein, trichostatin A and nicotinamide can direct hAESCs differentiation into RPE like cells. The differentiated cells display the morphology, marker expression and cellular function of the native RPE cells, and noticeably express little MHC class II antigens and high level of HLA-G. Importantly, visual function and retinal structure of Royal College of Surgeon (RCS) rats, a classical animal model of retinal degeneration, were rescued after subretinal transplantation with the hAESCs-derived RPE like cells. We established a high-efficient, low-cost and safety-guaranteed system for generating functional RPE cells from hAESCs. These results suggest a novel and ideal therapeutic strategy for retinal degeneration diseases
Project description:Retinal degeneration is the leading cause of irreversible blindness. Retinitis pigmentosa (RP) is a genetically heterogenous group of diseases. In the United States, approximately one in 4000 individuals is affected. RP begins with the loss of night vision due to the loss of rod photoreceptor cells. The disease progresses slowly with the loss of peripheral vision, and eventually leads to complete debilitating and irreversible blindness. The first mutation associated with human RP was identified in the gene encoding rhodopsin, the G-protein coupled receptor of rod photoreceptor cells. Mutations within the rhodopsin gene account for significant portion of RP cases. Specifically, mutations of the proline at residue 347 in rhodopsin have been linked to human RP. We are fortunate to have access to the P347S rhodopsin mutant mice. These mice represent an excellent transgenic mouse model of retinal degeneration. The P347S rhodopsin mutation is one of the best studied mutations, yet the mechanism by which the mutation causes degeneration is still unknown. One study has demonstrated that galectin-1 plays a role in degeneration of neuronal processes (1) and another study has shown that expression level of galectin-3 is elevated in retinas of patients with age-related macular degeneration. These studies in conjunction with the availibility of the P347S mutant mice have provided impetus to examine the pathogenesis of retinal degeneration in the context of the possible role of glycans and glycan-binding proteins. The time course of photoreceptor degeneration in the P347S mouse model has been carefully studied. In these mice, degeneration is barely detectable at 1 month of age, yet biochemical evidence suggests that the rod photoreceptor cells have already begun to die. At 4 months of age, approximately half of the rod photoreceptor cells have degenerated. To distinguish involvement of glycogens at the various stages of retinal degeneration, we have collected retinas of wild type and the mutant mice at four time points (1, 2, 3, and 4 months of age). This will allow us to identify the genes that target early, mid- and late stages of the retinal degeneration process. Thus we request the analysis of total 24 samples as specified below: Age Group (months) Mice No of samples at each time point 1 Wild type 3 2 Wild type 3 3 Wild type 3 4 Wild type 3 1 P347S 3 2 P347S 3 3 P347S 3 4 P347S 3 Total 24.
Project description:Dysfunctional humoral and cellular innate immunity are key components in the development and progression of age-related macular degeneration (AMD). Specifically, chronically activated microglia and their disturbed regulatory system contribute to retinal degeneration. Galectin-3, a b-galactose binding protein, is a potent driver of macrophage and microglia activation and has been implicated in neuroinflammation, including neurodegenerative diseases of the brain. Here, we report that galectin-3 is strongly upregulated in reactive retinal microglia of AMD patients and in two related mouse models of retinal degeneration. Specific targeting of galectin-3 by genetic knockout or using the small-molecule inhibitor TD139 blocks microglia reactivity and protects from retinal damage in different models of light-induced retinal degeneration. These data define galectin-3 as potent driver of retinal degeneration and highlight the protein as a drug target for ocular immunomodulatory therapies.
Project description:Photoreceptor degeneration is the central event leading to visual impairment or blindness in most retinal diseases. However, the discovery of safe and effective therapeutic strategies conferring photoreceptor protection remains challenging. A systems pharmacology approach, synergistically targeting distinct cellular pathways could provide an effective strategy for evaluating, preventing or treating retinal dystrophies. Here this concept was investigated using a mouse model of light-induced retinal degeneration. We show that a combination of FDA-approved drugs acting on different G protein-coupled receptors in a synergistic manner could protect retinas against light-induced degeneration when each drug in the combination treatment was administered at a sub-therapeutic dose. Furthermore, transcriptome analyses demonstrated that such combined treatments also preserved patterns of retinal gene expression more characteristic of the normal retina than did single therapies at higher doses. The current study thus supports a new systems pharmacology approach that may extend to other complex neurodegenerative disorders in addition to retinal diseases.