Hyaluronan and CD44 are Novel Targets for Acute Lung injury

描述（由申请人提供）：急性肺损伤（ALI）是危重患者发病和死亡的主要原因，其治疗策略非常有限。ALI的定义特征和干预目标是肺血管内皮细胞（EC）屏障的破坏，其导致流体、蛋白质和细胞渗漏到肺的空气空间中。我们的新研究表明，细胞外基质成分，透明质酸（HA），和它的细胞表面受体家族，CD 44，在正常EC功能和血管生成是重要的。我们已经证明，高分子量HA（HMW-HA）连接的CD 44亚型，CD 44（标准形式）的结果在Rac 1依赖的皮质肌动蛋白的形成和EC屏障增强。相比之下，低分子量HA（（LMW-HA），在病理状态下由透明质酸酶产生）占据CD 44变体10（CD 44 v10）并介导RhoA依赖性肌动蛋白应力纤维形成和EC屏障破坏。因此，增强HMW-HA/CD 44 s信号通路的作用，减弱LMW-HA/CD 44 v10信号通路的作用，可能为通过增强肺血管完整性治疗ALI提供一种新的策略。具体目标#1将通过确定HMW-HA/CD 44通过包含小窝蛋白-1和dynamin 2的称为小窝蛋白富集微区（CEM）的专门结构对EC屏障功能的调节来扩展我们已发表的和初步的数据。在具体目标#2中，我们将确定HMW-HA介导的通过抑制RhoA GT3和激活Rac 1 GT3对肺EC屏障破坏的保护作用。最后，具体目标#3将采用旨在进一步验证HA/CD 44调节血管完整性的治疗策略（CD 44 v10特异性阻断抗体、透明质酸酶和Rho激酶抑制剂，siRNA），使用ACE抗体定向纳米载体技术靶向肺内皮。这些研究将产生对HMW-HA保护免受ALI相关病理生物学和炎性肺损伤的新的机制见解，以及提供减少ALI介导的肺损伤的新的治疗策略。

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.