Hyaluronan and CD44 are Novel Targets for Acute Lung injury

描述(由申请人提供)：急性肺损伤(ALI)的治疗策略极其有限，ALI是危重患者发病率和死亡率的主要原因。ALI的一个明显特征和干预目标是肺血管内皮细胞(EC)屏障的破坏，导致液体、蛋白质和细胞泄漏到肺的空气空间。我们新的研究表明，细胞外基质成分透明质酸(HA)及其细胞表面受体家族CD44在正常的EC功能和血管生成中起重要作用。我们已经证明，高分子HA(HMW-HA)连接CD44异构体CD44s(标准型)导致依赖于rac1的皮质肌动蛋白的形成和EC屏障的增强。相比之下，低分子HA((LMW-HA)，在病理状态下由透明质酸酶产生)占据CD44变异体10(CD44v10)，并介导RhoA依赖的肌动蛋白应激纤维的形成和EC屏障的破坏。因此，加强HMW-HA/CD44s信号通路的作用，减弱LMW-HA/CD44v10信号通路的作用，可能通过增强肺血管完整性为ALI提供新的治疗策略。具体目标1将通过确定HMW-HA/CD44s通过含有小窝蛋白-1和Dynamin 2的特殊结构(称为小窝蛋白富集型微域(CEM))对EC屏障功能的调节来扩展我们已发表的和初步的数据。在特定目标2中，我们将通过抑制RhoA GTP酶和激活rac1 GTP酶来确定HMW-HA介导的对肺EC屏障破坏的保护作用。最后，特殊目标#3将采用治疗策略，旨在进一步验证HA/CD44对血管完整性的调节(CD44v10特异性阻断抗体、透明质酸酶和Rho激酶抑制剂，siRNA)，使用ACE抗体导向的纳米载体技术来靶向肺内皮细胞。这些研究将为HMW-HA对ALI相关的病理生物学和炎症性肺损伤的保护提供新的机制见解，并为减少ALI介导的肺损伤提供新的治疗策略。 公共卫生相关性：急性肺损伤(ALI)的治疗策略极其有限，ALI是危重患者发病率和死亡率的主要原因。我们正在研究高分子透明质酸(HMW-HA)的潜在用途，HMW-HA是一种自然存在于体内的物质，通过增强血管完整性来治疗ALI。我们的研究将对HMW-HA在ALI相关疾病过程中的保护作用产生新的机制见解，并提供新的治疗方式来减少ALI介导的肺损伤。

DESCRIPTION (provided by applicant): Therapeutic strategies for acute lung injury (ALI), a major cause of morbidity and mortality in critically ill patients, are extremely limited. A defining feature of ALI and a target for intervention is the disruption of the lung vascular endothelial cell (EC) barrier which results in leakage of fluid, protein and cells into the airspaces of the lungs. Our novel studies indicate that the extracellular matrix component, hyaluronan (HA), and its cell surface receptor family, CD44, are important in normal EC function and angiogenesis. We have demonstrated that the ligation of the CD44 isoform, CD44s (standard form) by high molecular weight HA (HMW-HA) results in Rac1-dependent cortical actin formation and EC barrier enhancement. In contrast, low molecular weight HA ((LMW-HA), produced in pathological states by hyaluronidase enzymes) occupies CD44 variant 10 (CD44v10) and mediates RhoA-dependent actin stress fiber formation and EC barrier disruption. Therefore, enhancing the effects of HMW-HA/CD44s signaling pathways and diminishing the effects of LMW-HA/CD44v10 signaling may provide a novel therapeutic strategy for ALI via enhancing pulmonary vascular integrity. Specific Aim #1 will expand our published and preliminary data by determining HMW-HA/CD44s regulation of EC barrier function by specialized structures called caveolin-enriched microdomains (CEM) containing caveolin-1 and dynamin 2. In Specific Aim #2, we will determine HMW-HA-mediated protection from pulmonary EC barrier disruption through inhibition of RhoA GTPase and activation of Rac1 GTPase. Finally, Specific Aim #3 will employ therapeutic strategies designed to further validate HA/CD44 regulation of vascular integrity (CD44v10-specific blocking antibodies, hyaluronidase and Rho Kinase inhibitors, siRNA) using ACE antibody-directed nanocarrier technologies to target the pulmonary endothelium. These studies will yield novel mechanistic insights into HMW- HA's protection from ALI-associated pathobiology and inflammatory lung injury as well as provide novel therapeutic strategies to reduce ALI-mediated lung injury. PUBLIC HEALTH RELEVANCE: Therapeutic strategies for acute lung injury (ALI), a major cause of morbidity and mortality in critically ill patients, are extremely limited. We are examining the potential use of high molecular weight hyaluronan (HMW-HA), a substance found naturally in the body, to treat ALI through enhancement of vascular integrity. Our studies will yield novel mechanistic insights into HMW-HA's protection from ALI-associated disease processes as well as provide novel treatment modalities to reduce ALI-mediated lung injury.