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Mechanisms of toll-like receptor-mediated neurotoxicity in the ischemic retina

Toll样受体介导的缺血性视网膜神经毒性机制

基本信息

批准号：
9207596
负责人：
Dmitry V Ivanov
金额：
$ 37.94万
依托单位：
UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-01 至 2021-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9207596
关键词：
Affect Animal Model Animals Astrocytes Biochemical Biological Blindness CASP4 gene Caspase Cell Death Cell Survival Cells Clinical Data Development Foundations Impairment Individual Inflammasome Inflammation Inflammatory Inflammatory Response Injury Interferon Type I Interferons Interleukins Ischemia Knock-out Light Mediating Microglia Molecular Muller&apos s cell Necrosis Neurons Pathogenesis Pathologic Pathology Patients Play Production Quality of life Reactive Oxygen Species Receptor Signaling Retina Retinal Retinal Degeneration Retinal Diseases Retinal Ganglion Cells Role Signal Transduction TLR4 gene Techniques Testing Therapeutic Tissues Toll-like receptors Toxic effect Up-Regulation Visual impairment Wild Type Mouse cell type functional status knockout animal neuroprotection neurotoxic neurotoxicity novel therapeutic intervention novel therapeutics prevent response retinal damage

项目摘要

PROJECT SUMMARY Ischemic injury to retinal tissue is a clinical condition that frequently leads to visual impairments and blindness, affecting patients' quality of life and functional status. But a more rigorous understanding of the mechanisms of ischemia-induced retinal injury will be required if new therapies for the management of retinal disease are to be developed. Previously, we demonstrated the deleterious role of toll-like receptor 4 (Tlr4) signaling in retinal inflammation and damage triggered by ischemic conditions. Since Tlr4 signaling consists of two distinct signaling cascades, Myd88- and Trif-dependent, we individually evaluated the role of these cascades in ischemic retinae. Available evidence appears to indicate that the effects mediated by Trif and Myd88 signaling in ischemic retinal tissue are retina-specific and asymmetric. Whereas inactivation of either Trif or Myd88 resulted in significantly reduced inflammation in ischemic retinal tissue, ischemic retinae of Myd88-deficient animals demonstrated significantly higher levels of damage than ischemic retinae of Trif-deficient animals. We also noted that ischemia-induced Trif signaling directly facilitates necrotic retinal ganglion cell (RGC) death. Furthermore, we demonstrated that RGC necrosis, which exacerbates retinal injury by promoting more inflammation, can be regulated in some cases (termed “necroptosis”). Since Trif signaling can mediate cell necroptosis, we hypothesize in Aim 1 that Trif signaling mediates ischemia-induced retinal damage by promoting RGC necroptosis. In addition, Trif-dependent signaling differs from the Myd88 signaling cascade in its ability to activate type I interferon (IFN) signaling. It was previously shown that Trif, via its activation of IFN, activates caspase-11 (Casp11), which can in turn mediate cell death both directly and indirectly (via NLRP3 inflammasome activity and interleukin-1b [Il1b] release). In light of our finding of high levels of Casp11 and inflammasome activity in ischemic RGCs, we hypothesize in Aim 2 that ischemia-induced Trif signaling mediates Casp11 activation, which in turn mediates RGC death both directly and indirectly (via elevated inflammatory responses). Finally, since Müller glia (MG) activity is associated with neuroprotection in nearly every pathological condition in the retina, we hypothesize in Aim 3 that ischemia-induced, MG-specific, Tlr4- dependent neuroprotective activity prevails over neurotoxic activity to facilitate survival of ischemic RGCs. If the proposed hypotheses are found to be correct, we will be able to explain the asymmetric roles of Trif and Myd88 in ischemic retinal tissue: while Myd88 regulates glial toxicity (astrocytes and microglia) and neuroprotection (MG) in ischemic retinae, Trif activates both aforementioned phenomena while also directly mediating RGC death, thus promoting more significant retinal damage than Myd88. To evaluate our hypotheses, we will use animal models and employ a wide range of biochemical, molecular, and cell biological techniques. By completing this project, we will assemble an intellectual foundation for new retina-specific therapeutic strategies that can more effectively treat ischemic retinal diseases.

项目总结