Targeting integrin outside-in signaling for treating sepsis

在严重的脓毒症中，感染引起的全身炎症导致血管渗漏、微血管血栓形成、弥散性血管内凝血(DIC)、多器官功能障碍、出血和循环衰竭，导致高死亡率。抗生素和标准护理方案是有帮助的，但最终对许多患者无效。尽管进行了多年的密集研究，FDA批准用于治疗脓毒症的唯一新药是激活蛋白C(APC，Xgris®)，它通过抑制凝血酶的生成来预防血栓形成和减少炎症。然而，Xgris也造成了出血，这超过了它的好处，导致了退出市场。因此，脓毒症的新的挽救生命的治疗方法有一个迫切的未得到满足的需求。在这里，我们建议开发一种治疗脓毒症的新药，它既能有效地抑制血栓形成，又能抑制炎症，而不会导致出血。这一创新药物针对的是最近在实验室发现的一种新的整合素信号机制(Gong等人科学2010，沈等人，自然2013，沈MBoc 2015，庞血2018)，他表明整合素自外向内信号需要G蛋白亚基Galpha13和几个整合素Beta亚基(包括血小板中的Beta3和白细胞中的Beta2)细胞质区域中保守的Exe基序之间的直接相互作用。Galpha13-整合素相互作用的中断取消了由外向内的信号传递，而不影响对止血至关重要的整合素的配体结合功能。我们设计了一种选择性的Beta3 Galpha13结合Exe基序的多肽抑制剂，它有效地抑制了闭塞性血管内血栓形成，而不会导致过度出血(Shenet al，Natural，2013)。由于整合素Outside-in信号不仅在血栓形成中起关键作用，而且在炎症中也起关键作用，我们设计了一种Exe基序多肽MB2mP6，它能抑制Galpha13与血小板中的β3整合素以及白细胞中的β2整合素的相互作用。在I期研究中，我们表明，在脓毒症发作后立即或6小时后使用MB2mP6治疗小鼠，可以有效地抑制脓毒症小鼠的炎症和血栓形成，显著降低死亡率。这种药物还可以保护肺部免受血管渗漏和微血栓的影响，这可能会导致ARDS，这是败血症的严重后果，也是SARS冠状病毒2型感染(COVID19)和流感死亡的主要原因。重要的是，这种新药不会加剧身体损伤或炎症引起的出血。我们进一步开发了新型脂质稳定的高负载多肽纳米粒(HLPN)，用于有效的体内药物输送。在这个第二阶段的应用中，我们建议(1)评估MB2mP6作为抗生素和标准护理的辅助治疗细菌和病毒感染后的脓毒症和ARDS的疗效。(2)评价MB2mP6的安全性(无抗止血活性)和毒性。(3)扩大GMP级新药的生产和IND的制备和提交。这种针对血栓形成和过度炎症的新药，在不损害止血和血管完整性的情况下，有望治疗脓毒症以及由脓毒症和病毒感染引起的ARDS。

In severe sepsis, systemic inflammation induced by infection leads to vascular leakage, microvascular thrombosis, disseminated intravascular coagulation (DIC), multiple organ dysfunction, hemorrhage and circulatory collapse, resulting in high mortality. Antibiotics and standard care regimens are helpful, but ultimately ineffective for many patients. Despite years of intensive research, the only new drug FDA approved for treatment of sepsis is activated protein C (APC, Xigris®), which prevents thrombosis and reduces inflammation by inhibiting thrombin generation. However, Xigris also causes hemorrhage, which outweighed its benefits and resulted in withdrawal from the market. Thus, there is an urgent unmet need for new life-saving treatment of sepsis. Here, we propose to develop a new drug for sepsis treatment, which potently inhibits both thrombosis and inflammation without causing bleeding. This innovative drug targets a novel integrin signaling mechanism recently discovered in the lab of Xiaoping Du, co-investigator of this application (Gong et al Science 2010, Shen et al, Nature 2013, Shen MBoC 2015, Pang Blood 2018), who showed that integrin outside-in signaling requires direct interaction between the G protein subunit Galpha13 and an ExE motif conserved in the cytoplasmic domain of several integrin Beta subunits (including Beta3 in platelets and Beta2 in leukocytes). Disruption of Galpha13-integrin interaction abolishes outside-in signaling without affecting the ligand binding function of integrins important for hemostasis. We designed a selective peptide inhibitor of the Beta3 Galpha13 binding ExE motif that potently inhibited occlusive intravascular thrombosis without causing excessive bleeding (Shen et al, Nature, 2013). Because integrin outside-in signaling is critical not only in thrombosis but also in inflammation, we designed an ExE motif peptide, MB2mP6, that inhibits Galpha13 interaction with Beta3 integrins in platelets and also Beta2 integrins in leukocytes. In Phase I studies, we showed that treatment of mice with MB2mP6 immediately after or 6 h after sepsis onset potently inhibits inflammation and thrombosis in septic mice, significantly reducing mortality. This drug also protects lungs from vascular leakage and microthrombosis that can lead to ARDS, a severe consequence of sepsis and a major cause of mortality of SARS-coronavirus 2 infection (COVID19) as well as influenza. Importantly, this new drug did not exacerbate hemorrhage induced by either physical injury or inflammation. We further developed novel lipid-stabilized high-loading peptide nanoparticles (HLPN) for efficient in vivo drug delivery. In this Phase II application, we propose to (1) Evaluate the efficacy of MB2mP6 as an adjunct to antibiotics and standard care in treating sepsis and ARDS following bacterial and viral infection. (2) Evaluate the safety (absence of anti-hemostatic activity) and toxicity of MB2mP6 (3) Scale up production of a GMP-grade new drug and IND preparation and submission. This novel drug that targets thrombosis and excess inflammation, without impairing hemostasis and vascular integrity, holds promise for treating sepsis as well as ARDS arising from sepsis as well as viral infections.