Aryl hydrocarbon receptor and bilirubin as therapeutic target for ICH

芳烃受体和胆红素作为脑出血的治疗靶点

• 批准号: 10299427
• 负责人: Jaroslaw Aronowski
• 金额: $ 46.49万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10299427
• 关键词: ABCB1 gene; Affect; Age; Agonist; Animals; Anti-Inflammatory Agents; Antioxidants; Aryl Hydrocarbon Receptor; Bilirubin; Binding; Biological; Blood; Brain; Brain Injuries; Cerebral hemisphere hemorrhage; Clinical; Cytoprotection; Cytosol; DNA; Data; Drug Metabolic Detoxication; Erythrocytes; Erythrophagocytosis; Excision; Excretory function; Extracellular Space; Functional disorder; Genes; Genetic Transcription; Glutathione S-Transferase; Health; Hematoma; Heme; Hemoglobin; Hemorrhage; Homeostasis; In Vitro; Inflammation; Inflammatory; Inflammatory Response; Injury; Knockout Mice; Mediating; Membrane; Microglia; Molecular; Neurologic; Neurological outcome; Nuclear Translocation; Nucleic Acids; Pathway interactions; Phagocytes; Phagocytosis; Phenotype; Pigments; Play; Precipitation; Process; Production; Proteins; Pump; Receptor Activation; Recovery; Research; Resolution; Role; Small Interfering RNA; Solubility; Sulforaphane; Therapeutic; activating transcription factor; base; brain cell; brain repair; cell injury; heme oxygenase-1; in vivo; inhibitor/antagonist; injured; macrophage; mouse model; neurological recovery; new therapeutic target; nuclear factor-erythroid 2; preservation; prevent; repaired; response; restoration; sex; therapeutic target; transcription factor; water solubility

After intracerebral hemorrhage (ICH), phago(endo)cytosis of hematoma components [erythrocytes (RBC), hemoglobin (Hb) and heme], by microglia/macrophages (MMΦ) is essential for removal/detoxification of the hematoma, resolution of inflammation, and restoration of brain homeostasis for optimal neurological recovery. Thus, strategies for protecting MMΦ from injury during engulfment of toxic hematoma components is critical for the efficiency of MMΦ in clearing the hematoma after ICH. Upon engulfment of RBC/Hb/heme from the hematoma, MMΦ express heme oxygenase 1 (HO1; encoded by Hmox1), which catabolizes heme to produce large amounts of bilirubin (BrB) within MMΦ. Normally BrB is a beneficial and potent antioxidant; however, when intracellular BrB accumulates to very high concentrations, it may reversibly inhibit HO1 activity, thus reducing MMΦ' function and even precipitate onto biological membranes or nucleic acids (due to its poor water solubility), causing injury and compromising MMΦ' integrity. On the cellular level, BrB acts as an endogenous agonist for a pleotropic transcription factor, aryl hydrocarbon receptor (AhR), a protein that, based on prior research and our preliminary data, plays essential roles in supporting MMΦ for their integrity and function during hematoma clearance to enhance brain recovery after ICH. Our preliminary studies established that intracellularly elevated free BrB in microglia (MΦ), during erythrophagocytosis, activates AhR to promote transcription of BrB handling proteins, ligandins [(LGN/glutathione S-transferases), which bind fBrB to increase its cytosol solubility] and multidrug resistance protein 1 [(Mrp1)14, 15, which mediates efflux of BrB from the intracellular compartment to the extracellular space]. Without fast clearance of intracellularly accumulating fBrB, MΦ are injured and function less efficiently, and produce large amount of proinflammatory factors that could cause severe brain damage. In addition, we established that BrB-activated AhR promotes phagocytosis and upregulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of cellular oxidative defense for hematoma detoxification, and a potential therapeutic target for ICH. Furthermore, we established that AhR activity regulates RelB nuclear translocation, suggesting that AhR may also interact with RelB to transactivate genes involving inflammation resolution. Ultimately, using the mouse model of ICH, we found very promising therapeutic benefits of AhR agonist ITE19-21, alone and even more so in combination with the activator of Nrf2 (sulforaphane, SF), regarding neurological outcome and hematoma clearance. Our hypothesis is that after ICH, activation of AhR/RelB in MMΦ during hematoma removal by BrB (or other non-toxic AhR activators) is vital for preserving MMΦ' survival/phagocytic functions, avoiding self-inflicted damage, retention of reparative phenotype, ultimately leading to a more efficient MMΦ-mediated hematoma clearance and repair after ICH. Activation of AhR could be a novel therapeutic target for ICH.

脑出血 (ICH) 后，血肿成分 [红细胞 (RBC)、 小胶质细胞/巨噬细胞 (MMΦ) 的血红蛋白 (Hb) 和血红素] 对于去除/解毒至关重要 血肿、炎症消退和恢复大脑稳态以实现最佳神经功能恢复。 因此，保护​​ MMΦ 在有毒血肿成分吞噬过程中免受损伤的策略对于 MMΦ清除ICH后血肿的效率。 在吞噬血肿中的 RBC/Hb/血红素后，MMΦ 表达血红素加氧酶 1（HO1；编码为 Hmox1)，在 MMΦ 内分解血红素产生大量胆红素 (BrB)。通常 BrB 是 有益且有效的抗氧化剂；然而，当细胞内 BrB 积累到非常高的浓度时， 可能可逆地抑制 HO1 活性，从而降低 MMΦ 的功能，甚至沉淀到生物膜上 或核酸（由于其水溶性差），造成损伤并损害 MMΦ 的完整性。 在细胞水平上，BrB 充当多效性转录因子芳基烃的内源性激动剂 受体（AhR），一种基于先前研究和我们的初步数据的蛋白质，在 支持 MMΦ 在血肿清除过程中的完整性和功能，以增强 ICH 后的大脑恢复。 我们的初步研究表明，在小胶质细胞 (MΦ) 中，细胞内游离 BrB 升高 噬红细胞作用，激活 AhR 促进 BrB 处理蛋白、配体蛋白的转录 [（LGN/谷胱甘肽 S-转移酶），结合 fBrB 以增加其胞质溶解度] 和多药耐药性 蛋白 1 [(Mrp1)14, 15，介导 BrB 从细胞内区室流出到细胞外空间]。 如果不能快速清除细胞内积累的 fBrB，MΦ 就会受到损伤并且功能效率降低，并且 产生大量促炎因子，可能导致严重的脑损伤。此外，我们 确定 BrB 激活的 AhR 促进吞噬作用并上调核因子的表达 红细胞 2 相关因子 2 (Nrf2)，血肿解毒细胞氧化防御的主要调节因子， 以及 ICH 的潜在治疗靶点。此外，我们确定 AhR 活性调节 RelB 核 易位，表明 AhR 也可能与 RelB 相互作用，反式激活涉及炎症的基因 解决。最终，通过使用 ICH 小鼠模型，我们发现了 AhR 非常有前景的治疗益处 激动剂 ITE19-21，单独使用，与 Nrf2 激活剂（萝卜硫素，SF）联合使用更是如此， 神经系统结果和血肿清除。 我们的假设是，ICH后，在BrB（或其他药物）清除血肿期间，MMΦ中的AhR/RelB被激活 无毒的 AhR 激活剂）对于保持 MMΦ 的生存/吞噬功能、避免自残至关重要 损伤，保留修复表型，最终导致更有效的 MMΦ 介导的血肿 ICH 后的清除和修复。 AhR 的激活可能成为 ICH 的新治疗靶点。