Inflammation in MERTK-dependent retinitis pigmentosa

MERTK 依赖性色素性视网膜炎中的炎症

• 批准号: 10743622
• 负责人: SILVIA C FINNEMANN
• 金额: $ 67.97万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2028-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10743622
• 关键词: 3 year old; Ablation; Animal Model; Anti-Inflammatory Agents; Biological Assay; Biological Process; Blindness; CISH gene; Cell Culture Techniques; Characteristics; Clinical; Complement; Data; Disease; Dissection; Dose; Etiology; Event; Eye; FDA approved; Foundations; Functional disorder; Gene Expression; Genetic; Homeostasis; Human; ITIM; In Vitro; Infiltration; Inflammation; Inflammatory; JAK1 gene; Knock-out; MERTK gene; Mediating; Microglia; Modality; Muller' s cell; Mus; Mutant Strains Mice; Mutate; Mutation; Outcome; Pathologic; Patients; Phagocytes; Phagocytosis; Phagocytosis Inhibition; Phenocopy; Photoreceptors; Point Mutation; Process; Rattus; Receptor Protein-Tyrosine Kinases; Regimen; Reporting; Retina; Retinitis Pigmentosa; Rodent; Role; STAT3 gene; Severities; Signal Pathway; Signal Transduction; Site; Source; Structure; Structure of retinal pigment epithelium; Surgeon; Tamoxifen; Testing; Therapeutic; Tyrosine; Visual Fields; college; design; early onset; glial activation; inhibitor; insight; loss of function; monocyte; mouse model; novel; novel therapeutics; paralogous gene; pharmacologic; photoreceptor degeneration; postnatal; preservation; prevent; receptor function; reconstitution; small hairpin RNA; small molecule; therapeutic target; translational study; treatment duration; treatment optimization

PROJECT SUMMARY/ABSTRACT The biological process heretofore implicated in MERTK loss-of-function-associated Retinitis Pigmentosa (RP) is defective phagocytosis of shed photoreceptor outer segments (POS) by retinal pigment epithelium (RPE) leading to photoreceptor (PR) degeneration. Here we propose a shift in this paradigm. We have demonstrated that the precise genetic ablation of Mertk in mice (Mertk -/- V2) results in deficient phagocytosis, but not PR degeneration. Furthermore, PR degeneration in the original Mertk knockout (Mertk -/- V1 that is hypomorphic from Tyro3) or Mertk -/- V2 Tyro3 -/- V2 mice is associated with RPE inflammation. Therefore, we hypothesize that loss of MERTK anti- inflammatory signaling in the RPE is a critical event leading to RP. To test this hypothesis, we propose to (i) conditionally ablate Mertk in Tyro3 -/- RPE to test if this recapitulates RPE inflammation seen in germline Mertk - /- V1 and Mertk -/- V2 Tyro3 -/- V2 mice. An alternate possibility, RPE inflammation when Mertk is conditionally ablated in Tyro3 -/- RPE notwithstanding, is that inflammation is a secondary consequence of loss of MERTK-mediated phagocytosis and the consequent build-up of POS debris. We do not see POS build up even at 6 months in Mertk -/- V2 or Mertk -/- V3 mice. We also detect RPE inflammation before eye opening (at p10) and thus inflammation in the absence of MERTK is likely primary. To directly test this, (ii) we have generated a unique set of mouse models wherein either the phagocytosis or anti-inflammatory signaling function of MERTK has been exclusively mutated, leaving the remaining function intact. These mouse models will allow us to definitively test the outcome of loss of MERTK-mediated phagocytosis alone in PR degeneration, as well as uncouple the effects of loss of MERTK anti-inflammatory signaling alone from that of loss of MERTK-mediated phagocytosis. Complementing these studies, we will test the orthologous mutations in differentiated human primary RPE in terms of their effect on inducing RPE inflammation in presence or absence of POS. If inflammation underlies the etiology of MERTK loss-of-function-associated RP, can it be therapeutically targeted to protect against vision loss? (iii) We have obtained promising preliminary data that the FDA-approved JAK1/2 inhibitor ruxolitinib reduces inflammatory gene expression in the Mertk -/- V1 RPE and the severity of PR degeneration in Mertk -/- V1 mice. Building on this proof-of-concept, we will optimize the ruxolitinib regimen (dose and duration of treatment) through dose- escalation studies to determine maximum protection against PR degeneration and vision loss. Taken together, these three independent, orthogonal approaches are expected to reveal mechanistic insight supporting a novel role of inflammation within the RPE itself as causally relevant to MERTK loss-of-function-associated RP, as well as, provide a therapeutic avenue using small molecule JAK1/2 inhibitors (“Jakinibs”) already in clinical use for this severe, early-onset form of RP.

项目摘要/摘要 迄今为止与MERTK功能失调相关的色素性视网膜炎（RP）的生物过程是 视网膜色素上皮（RPE）前导的脱落光感受器外部片段（POS）的吞噬作用有缺陷 到感光器（PR）变性。在这里，我们提出了此范式的转变。我们已经证明了 MITE中MERTK的精确遗传消融（MERTK - / - V2）导致吞噬作用不足，但不能导致PR变性。 此外，原始MERTK基因敲除（Mertk - /-V1是Tyro3）或MERTK的PR变性 - / - V2 Tyro3 - / - V2小鼠与RPE注射有关。因此，我们假设MERTK抗 - RPE中的炎症信号传导是导致RP的关键事件。为了检验这一假设，我们建议（i） 有条件地在tyro3 - / - rpe中燃烧MERTK，以测试是否概括了在生殖线Mertk中看到的RPE注射 - /-V1和MERTK - / - V2 TYRO3 - / - V2小鼠。另一种可能性，当MERTK有条件地融为一体时，RPE注入 在Tyro3 - / - RPE中，炎症是MERTK介导的丧失的次要结果 吞噬作用和随之而来的POS碎片堆积。我们看不到POS即使在6个月的 Mertk - / - V2或Mertk - / - V3小鼠。我们还检测到眼注射前的RPE注射（在P10处），从而注射 在不存在MERTK的情况下，可能是主要的。为了直接测试这一点，（ii）我们生成了一组唯一的鼠标 其中MERTK的吞噬作用或抗炎信号传导函数已完全是完全的模型 突变，使剩余功能完好无损。这些鼠标模型将使我们能够明确测试结果 仅在PR变性中单独失去了MERTK介导的吞噬作用，并取消了丧失的影响 MERTK抗炎信号仅由于MERTK介导的吞噬作用的丧失。补充 这些研究，我们将根据其作用来测试分化的人类原发性RPE中的直系突变 在存在或不存在POS的情况下诱导的RPE注射。如果注射是MERTK的病因的基础 功能丧失相关的RP，是否可以热靶向以防止视力丧失？ （iii）我们有 获得了有希望的初步数据，即FDA批准的JAK1/2抑制剂ruxolitinib降低了炎症 MERTK - / - V1 RPE中的基因表达以及MERTK - / - V1小鼠中PR变性的严重程度。基于此 概念验证，我们将通过剂量优化鲁uxolitinib方案（剂量和治疗持续时间） 升级研究以确定对PR变性和视力丧失的最大保护。在一起， 这三种独立的正交方法有望揭示支持新颖的机械洞察力 炎症在RPE本身中的作用与MERTK功能丧失相关的RP也随意相关 AS，使用小分子JAK1/2抑制剂（“ Jakinibs”）提供治疗途径 这种严重的早期发作形式的RP。