RIPK1: A new target for traumatic brain injury?

描述(申请人提供)：坏死是人类疾病的一个主要因素，然而，由于其被认为是不可控制的，针对病理性坏死的特定治疗方法的开发工作很少。最近发现，肿瘤坏死因子受体家族成员下游的内在死亡途径可以引发坏死性死亡，这一发现对这一观点提出了挑战，这表明可以专门针对坏死进行抑制。我们最近开发了坏死素，一种有效的和选择性的小分子抑制剂，用于治疗由肿瘤坏死因子α和Fas受体启动的一种程序性坏死。Necrostatin-1被用来直接建立缺血性脑损伤后神经细胞死亡的主要成分--坏死性下垂。创伤性脑损伤是导致青壮年和儿童死亡和终生残疾的主要原因，然而创伤性脑细胞死亡及其相关的神经功能障碍的机制尚未得到很好的描述。我们已经证明，肿瘤坏死因子和Fas在小鼠控制性皮质撞击(CCI)后的组织病理学和功能结局中起着关键作用。由于肿瘤坏死因子和Fas是公认的坏死性下垂的诱因，我们调查了坏死性下垂是否与脑外伤后的预后有关。我们发现，Necrostatin-1减少了CCI后的组织损伤，并显著改善了小鼠的功能结局。这些结果表明，Necrostatin-1的靶点，受体相互作用蛋白激酶1(RIPK1)，可能是一个令人兴奋的新靶点，用于脑外伤的治疗。为了进一步研究RIPK1在脑损伤中的作用，我们提出了三个具体目标：1)使用基因敲除(RIPK1 ShRNA)和显性阴性(RIPK1 K45M)策略，在各种与脑损伤相关的体外神经细胞死亡范例中建立RIPK1在神经细胞死亡中的角色；2)通过AAV-8病毒载体转导带有shRNA RIPK1或RIPK1 K45M的体内神经元，证明RIPK1在脑创伤中的关键作用；以及3)在体外培养的神经元和脑损伤后的神经元中确定RIPK1相关的信号转导通路。公共卫生相关性：拟议项目中的工作可能为创伤性脑损伤患者提供一种新的治疗方法。建议的药物疗法可能会减少脑细胞死亡，并改善幸存者的学习和记忆，从而提高他们的生活质量。

DESCRIPTION (provided by applicant): Necrosis is a major contributor to human disease, however little effort has been made to develop specific therapies targeting pathologic necrosis due it its perceived uncontrolled nature. This notion has recently been challenged by the discovery that intrinsic death pathways down stream of tumor necrosis factor receptor family members can initiate necrotic death, suggesting that necrosis can be specifically targeted for inhibition. We have recently developed necrostatins, potent and selective small molecule inhibitors of "necroptosis", a form of programmed necrosis initiated by TNF alpha and Fas receptor. Necrostatin-1 was used to directly establish necroptosis as a major component of neuronal cell death after ischemic brain injury in vivo. Traumatic brain injury is a leading cause of death and life-long disability in young adults and children, however mechanisms of traumatic brain cell death and associated neurological dysfunction are not well characterized. We have shown that TNF and Fas play a key role in histopathological and functional outcome after controlled cortical impact (CCI) in mice. Since TNF and Fas are well established inducers of necroptosis, we investigated whether necroptosis contributes to outcome after TBI. We found that necrostatin-1 reduced tissue damage and markedly improved functional outcome following CCI in mice. These results suggest that the target of necrostatin-1, receptor interacting protein kinase 1 (RIPK1), may represent an exciting new target for TBI therapy. To further investigate the role of RIPK1 in TBI, we propose three Specific Aims: 1) Establish the role of RIPK1 in neuronal cell death in a variety of in vitro neuronal death paradigms related to TBI using knockdown (RIPK1 shRNA) and dominant negative (RIPK1 K45M) strategies; 2) Demonstrate a key contribution of RIPK1 to brain trauma in vivo, using AAV-8 viral vector transduction of neurons in vivo with shRNA RIPK1 or RIPK1 K45M constructs; and 3) Determine RIPK1-related signaling pathways operative during necroptosis in cultured neurons and in injured brain after TBI in vivo. PUBLIC HEALTH RELEVANCE: Work in the proposed project could render a new treatment for patients with traumatic brain injury. The proposed drug therapy might reduce brain cell death as well as improve learning and memory in survivors, and thereby improve their quality of life.