Nitric Oxide Metabolism in Acute Traumatic Brain Injury

脑挫伤(CC)是最常见的创伤性脑损伤(TBI)，常与血-脑损伤有关。 脑屏障(BBB)破坏，血管源性脑水肿(VCE)，颅内压(ICP)升高，以及 导致严重残疾或死亡的颅内出血。凝血酶与血脑屏障有牵连 损伤后的中断和VCE，但在不考虑ICH的情况下抑制它是潜在的风险，因为 凝血酶抑制会导致更多的出血。最近，我们实验室报道了CC诱导的新发现 内皮细胞一氧化氮(NO)氧化还原代谢产物的失衡(过氧亚硝酸盐/ONOOˉ&GT；S-亚硝基谷胱甘肽/GSNO) 作为一个潜在的靶点来减轻凝血酶诱导的血脑屏障破坏的早期事件。在培养的脑内皮细胞中 凝血酶诱导的ONOOˉ合成导致RhoA介导的内皮屏障破坏。另一方面， GSNO通过抑制RhoA介导抑制凝血酶诱导的内皮屏障破坏 机械装置。基于这些发现，这项建议的目标是评估针对NO失衡的药物 氧化还原代谢物(ONOO、ˉ和GT；GSNO)抑制非止血凝血酶活性和相关血管 颅脑损伤的病理学。ONOOˉ可抑制血小板的止血凝血活性。出于这个原因，拾荒者 ONOOˉ的清除剂FeTPPS可能也有利于控制出血和保护血脑屏障 颠覆。或者，全身外源性GSNO治疗也可能有益于血脑屏障的保护。 然而，如果损伤涉及活动性脑出血，这是潜在的风险，因为它在血液中具有抗血小板活性。 GSNO是在细胞内合成的，不易在细胞膜上扩散。在细胞中，GSNO是 被胞浆酶GSNO还原酶(GSNOR)降解，因此其抑制主要增加细胞内 同时使血液中GSNO的升高降至最低。基于上述基本原理，我们假设 N6022(GSNOR的抑制剂)将通过增加 细胞内GSNO水平，从而抑制内皮细胞对血脑屏障破坏的信号，同时最小化 血中GSNO水平升高，从而节约凝血活性。我们进一步假设 FeTTP对ONOOˉ的清除也通过抑制ONOOˉ的病理作用而提供额外的疗效 血脑屏障紊乱和血液凝固。为了检验这些假设，提出的具体目标是； 目的1：评价非代谢药物(GSNO、N6022和FeTPPS)治疗原发和非小细胞肺癌的疗效。 CC术后继发性损伤。 目的2：探讨非代谢药物在止血凝血过程中的作用 非止血内皮细胞信号通路引起的血脑屏障破坏。 拟议的研究是基于我们最近的发现，确定没有代谢物作为新的靶点 VCE。如果成功，这些研究将为以机制为基础的治疗范例带来新的见解 对于在院前和急诊科环境中导致VCE和ICP抑制的脑损伤的早期事件。

Cerebral contusion (CC), the most common form of traumatic brain injury (TBI), is often associated with blood- brain barrier (BBB) disruption, vasogenic cerebral edema (VCE), increased intracranial pressure (ICP), and intracranial hemorrhage (ICH) resulting in severe disability or death. Thrombin has been implicated in BBB disruption and VCE following the injury, but its inhibition without considering the ICH is potentially risky as thrombin inhibition can cause more bleeding. Recently, our laboratory reported novel findings of CC-induced imbalance of endothelial nitric oxide (NO) redox metabolites (peroxynitrite/ONOOˉ > S-nitrosoglutathione/GSNO) as a potential target to attenuate early events of thrombin-induced BBB disruption. In cultured brain endothelial cells, thrombin-induced ONOOˉ synthesis led to RhoA-mediated endothelial barrier disruption. On the other hand, GSNO treatment inhibited thrombin-induced endothelial barrier disruption via inhibiting RhoA-mediated mechanisms. Based on these findings, the goal of this proposal is to evaluate drugs targeting imbalanced NO redox metabolites (ONOOˉ > GSNO) for inhibition of non-hemostatic thrombin activity and associated vascular pathology in TBI. ONOOˉ inhibits platelet activity for hemostatic blood coagulation. For this reason, scavenging ONOOˉ by its scavenger FeTPPS might be also beneficial for control of bleeding as well as protection of BBB disruption. Alternatively, systemic exogenous GSNO treatment might also be beneficial for BBB protection. However, it is potentially risky, if the injury involves active ICH, because of its anti-platelet activity in the blood. GSNO is synthesized intracellularly and is not readily diffusible across the cell membrane. In the cells, GSNO is degraded by cytosolic enzyme GSNO reductase (GSNOR) and thus its inhibition primarily increases intracellular GSNO levels while minimizing the elevation of GSNO in blood. Based on the above rationale, we hypothesize that N6022 (inhibitor of GSNOR) will provide better outcomes than systemic GSNO treatment by increasing the intracellular GSNO levels, thus inhibiting the endothelial cell signaling for BBB disruption, while minimizing the elevation of blood GSNO levels, thus sparing the blood coagulation activity. We further hypothesize that scavenging ONOOˉ by FeTTPs also provide additional efficacy by inhibiting the pathological role of ONOOˉ in BBB disruption as well as blood coagulation. To test these hypotheses, the proposed specific aims are; Aim 1: To evaluate the efficacy of NO-metabolomic drugs (GSNO, N6022, and FeTPPS) on primary vs. secondary injuries following the CC. Aim 2: To investigate the role of NO-metabolomic drugs on hemostatic blood coagulation process and BBB disruption induced by non-hemostatic endothelial cell signaling pathway. The proposed studies are built upon our recent findings identifying NO metabolome as a novel target of VCE. If successful, these studies will result in new insights into the mechanism-based treatment paradigms for early events of TBI leading to inhibition of VCE and ICP in pre-hospital and emergency department settings.