Targeting integrin outside-in signaling for treating sepsis

在严重脓毒症中，感染引起的全身炎症会导致血管渗漏、微血管血栓形成、弥漫性血管内凝血（DIC）、多器官功能障碍、出血和循环衰竭，导致死亡率很高。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。尽管经过多年的深入研究，FDA批准用于治疗脓毒症的唯一新药是活化蛋白C（APC，Xigris®），它通过抑制凝血酶生成来预防血栓形成并减少炎症。然而，Xigris也会导致出血，这超过了它的好处，导致退出市场。因此，对于脓毒症的新的挽救生命的治疗存在迫切的未满足的需求。在这里，我们建议开发一种用于脓毒症治疗的新药，它可以有效地抑制血栓形成和炎症，而不会引起出血。这种创新药物靶向最近在本申请的联合研究者杜小平实验室发现的一种新型整合素信号传导机制（Gong等人Science 2010，Shen等人，Nature 2013，Shen MBoC 2015，Pang Blood 2018），他证明了整合素在细胞外在信号转导中需要G蛋白亚基Galpha 13和几种整合素β亚基胞质结构域中保守的ExE基序之间的直接相互作用（包括血小板中的β 3和白细胞中的β 2）。Galpha 13-整联蛋白相互作用的破坏消除了由外向内信号传导，而不影响对止血重要的整联蛋白的配体结合功能。我们设计了β 3 Galpha 13结合ExE基序的选择性肽抑制剂，其有效抑制闭塞性血管内血栓形成而不引起过度出血（Shen等人，Nature，2013）。由于整合素由外向内信号传导不仅在血栓形成中而且在炎症中至关重要，因此我们设计了一种ExE基序肽MB 2 mP 6，其抑制Galpha 13与血小板中的β 3整合素以及白细胞中的β 2整合素的相互作用。在I期研究中，我们显示在脓毒症发作后立即或6小时用MB 2 mP 6治疗小鼠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可能导致ARDS的血管渗漏和微血栓形成，这是脓毒症的严重后果，也是SARS冠状病毒2型感染（COVID 19）和流感死亡的主要原因。重要的是，这种新药不会加剧物理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载量肽纳米颗粒（HLPN），用于有效的体内药物递送。在该II期申请中，我们提出（1）评估MB 2 mP 6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的功效。(2)评估MB 2 mP 6的安全性（无抗止血活性）和毒性（3）GMP级新药的规模化生产和IND制备和提交。这种靶向血栓形成和过度炎症的新药，不损害止血和血管完整性，有望治疗败血症以及由败血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.