Vascular mechanisms of inhibition of sEH as a novel therapy for AD/ADRD

阿尔茨海默病和阿尔茨海默病及相关痴呆(AD/ADRD)是一种新兴的全球健康 护理危机。然而，潜在的机制还没有被很好地理解，以至于无法准确地翻译 医药。了解血管对AD/ADRD的贡献是当务之急，因为越来越多的证据表明 AD和糖尿病(DM)相关的ADRD与脑低灌流有关，67%的AD Gwas基因与脑低灌流有关 在脑血管中表达。最近的研究表明，可溶性环氧化物水解酶的还原 (SeH)对AD、DM-ADRD及脑低灌注动物模型的认知功能有一定的改善作用，其机制可能与抗AD、DM-ADRD和脑低灌注有关。 炎症和神经保护作用，但血管的作用被忽视。SeH是一种酶 将花生四烯酸(AA)衍生的EET和亚油酸(LA)衍生的EPOME转化为其 相应的二元醇DHETs和DiHOME。氧化脂质的变化，如升高的 在AD小鼠和ADRD患者中发现了DHETs/EETs和DiHOME/EpOME。我们初步发现 编码AA和LA的酶的基因(CYP2J2、2C8、2C9)中的SNPs催化EETs和EpOme， 和EPHX2编码的sEH与ARIC-NCS中的AD链接。我们还发现，一种高度选择性的sEH 抑制剂(SEHI)TPPU可逆转认知功能障碍、肌源性反应受损(MR)和 DM-ADRD和AD大鼠的脑血流量(CBF)和神经血管单位(NVU)功能障碍。此外， AD/ADRD大鼠表现为脑低灌流，血脑屏障渗漏增加，神经变性， 以及大脑Kir2.1活性降低，据报道与大脑毛细血管中PIP2水平降低有关 内皮细胞由于PLA2活性增强所致。这一提议将检验这样一个假设，即抑制sEH 协同调节PLA2-AA-EETs-DHETS和PLA2-LA-EpOME-DiHOME途径逆转 通过改善脑血流量自动调节，维持血脑屏障和脑血流，改善认知障碍和增强脑血流灌注 NVU功能。我们将比较血管功能(MR、CBF自动调节和功能性充血)、AD 经TPPU治疗的男女DM患者的表型、局部脑内PLA2、sEH、PlP2、Kir2.1和氧化脂质水平 ADRD和AD大鼠。我们还将比较EETs/DHETs的异构体混合物对血管的反应，以及 脑动脉和小动脉的EPOME/DiHOME，以及对高钾和高钾的血管扩张反应 从对照组、AD和ADRD大鼠分离的小动脉-毛细血管内氧脂的异构体混合物 进一步探索抑制sEH影响的具体途径。该项目将解决关键问题 关于sEHI对认知保护的血管贡献的认识差距和解释的下一步 SEH催化活性的生物学。这项提案产生的结果应该为 针对这些通路的新药的发现逆转了脑血管功能障碍，以预防 启动并延缓AD/ADRD的进展。 。

Alzheimer's disease and Alzheimer's disease and related dementias (AD/ADRD) is an emerging global health care crisis. However, underlying mechanisms have not been understood well enough for translation to precision medicine. Understanding vascular contribution to AD/ADRD is imperative since increasing evidence suggests AD and diabetic (DM)-related ADRD are associated with brain hypoperfusion, and 67% of AD GWAS genes are expressed in the cerebral vasculature. Recent studies demonstrated that reduction of soluble epoxide hydrolase (sEH) is beneficial to cognition in AD, DM-ADRD, and cerebral hypoperfusion animal models due to its anti- inflammatory and neuronal protective effects, but vascular contribution has been neglected. sEH is an enzyme that transforms arachidonic acid (AA)-derived EETs and linoleic acid (LA)-derived EpOMEs to their corresponding diols DHETs and DiHOMEs, respectively. Changes in oxylipins, such as the elevated ratio of DHETs/EETs and DiHOMEs/EpOMEs, were found in AD mice and ADRD patients. We preliminary found that SNPs in genes (CYP2J2, 2C8, 2C9) encoding enzymes that catalyze AA and LA to EETs and EpOMEs, and EPHX2 encoding sEH are linked with AD in the ARIC-NCS. We also found that a highly selective sEH inhibitor (sEHi) TPPU reversed cognitive disability, impaired myogenic response (MR) and autoregulation of cerebral blood flow (CBF), and neurovascular unit (NVU) dysfunction in DM-ADRD and AD rats. Moreover, AD/ADRD rats displayed brain hypoperfusion, enhanced blood-brain barrier (BBB) leakage, neurodegeneration, and reduced brain Kir2.1 activity that has been reported to associate with reduced PIP2 levels in cerebral capillary endothelial cells due to enhanced PLA2 activity. This proposal will test the HYPOTHESIS that inhibition of sEH synergistically modulates the PLA2-AA-EETs-DHETS and PLA2-LA-EpOMEs-DiHOMEs pathways to reverse cognitive impairments and enhance brain perfusion by ameliorating CBF autoregulation, maintaining BBB and NVU function. We will compare vascular function (MR, CBF autoregulation, and functional hyperemia), AD phenotypes, regional brain levels of PLA2, sEH, PlP2, Kir2.1, and oxylipins in TPPU-treated both sexes of DM- ADRD and AD rats. We will also compare vascular responses to isomer mixtures of EETs/DHETs, and EpOMEs/DiHOMEs in cerebral arteries and arterioles, and vasodilation responses to elevated potassium and isomer mixtures of oxylipins in arterioles-capillaries isolated from both sexes of control, AD, and ADRD rats to further explore the specific pathways that are affected by inhibition of sEH. This project will address critical knowledge gaps of the vascular contribution of sEHi on cognitive protection and the “next steps” in explaining the biology of the catalytic activity of the sEH. Results generated from this proposal should lay the foundation for the discovery of new drugs targeting these pathways to reverse cerebral vascular dysfunction to prevent the onset and slow the progression of AD/ADRD. .