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.

项目概要/摘要 迄今为止与 MERTK 功能丧失相关的色素性视网膜炎 (RP) 相关的生物过程是 视网膜色素上皮 (RPE) 对脱落的光感受器外节 (POS) 的吞噬作用有缺陷 在这里，我们提出了这种范式的转变。 小鼠中 Mertk 的精确基因消融 (Mertk -/- V2) 会导致吞噬作用缺陷，但不会导致 PR 变性。 此外，原始 Mertk 敲除（Mertk -/- V1，是 Tyro3 的亚形）或 Mertk 中的 PR 变性 -/- V2 Tyro3 -/- V2 小鼠与 RPE 炎症相关，因此，我们努力解决 MERTK 抗-/-的丧失。 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)。 有条件地消融 Tyro3 -/- RPE 中的 Mertk，以测试这是否重现了种系 Mertk 中观察到的 RPE 炎症 - /- V1 和 Mertk -/- V2 Tyro3 -/- V2 小鼠 另一种可能性是，当 Mertk 有条件消除时，RPE 发生炎症。 尽管在 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，即使在 6 个月后，我们也没有看到 POS 堆积。 Mertk -/- V2 或 Mertk -/- V3 小鼠我们还在睁眼前（第 10 页）检测 RPE 炎症，从而检测炎症。 在没有 MERTK 的情况下，为了直接测试这一点，我们已经生成了一组独特的小鼠。 MERTK 的吞噬作用或抗炎信号传导功能已被专门研究的模型 突变，而其余功能完好无损，这些小鼠模型将使我们能够明确地测试结果。 PR 变性中 MERTK 介导的吞噬作用的丧失，以及解开 MERTK 介导的吞噬作用丧失的影响 MERTK 抗炎信号仅来自于 MERTK 介导的吞噬作用的缺失。 在这些研究中，我们将测试分化的人类原发性 RPE 中的直系同源突变的影响 如果炎症是 MERTK 病因的基础，则在存在或不存在 POS 的情况下诱导 RPE 炎症。 功能丧失相关的 RP，是否可以通过治疗来预防视力丧失？ 获得了有希望的初步数据，表明 FDA 批准的 JAK1/2 抑制剂 ruxolitinib 可减少炎症 Mertk -/- V1 RPE 中的基因表达以及 Mertk -/- V1 小鼠中 PR 变性的严重程度。 为了验证概念，我们将通过剂量优化鲁索替尼方案（剂量和治疗持续时间） 升级研究以确定对 PR 退化和视力丧失的最大保护。 这三种独立、正交的方法有望揭示支持小说的机械见解 RPE 本身内炎症的作用与 MERTK 功能丧失相关的 RP 也有因果关系 为使用已在临床使用的小分子 JAK1/2 抑制剂（“Jakinibs”）提供治疗途径 这种严重的早发性 RP。