TGF-beta and Smad3 in intimalhyperplasia after vascular bypass

描述（由申请人提供）：每年有超过一百万的美国人需要介入治疗动脉粥样硬化性血管疾病。不幸的是，这些干预措施引发疾病复发或治疗血管再狭窄的发展。尽管已经开发了预防性治疗方法，但10-15%的冠状动脉和高达80%的下肢干预（取决于血管床）仍会发生再狭窄。进一步了解再狭窄的机制将有助于改进治疗方法的发展。两个主要过程导致再狭窄：1)新内膜增厚，称为内膜增生；2)血管壁直径改变，导致收缩或适应性重构。我们之前的发现证实了TGFß是参与这两个过程的主导因子。细胞因子TGFß在血管疾病中的作用一直是一个难题，因为在体外，TGFß产生高度分化的平滑肌细胞（SMC）表型，然而在体内，TGFß刺激SMC去分化和内膜增生。在过去的资助期内，我们发现了对这个难题的一个独特解释：Smad3水平升高，在血管干预后发展，将TGß转化为SMC去分化、增殖、迁移和炎症（MCP-1产生）的兴奋剂，以及细胞凋亡的抑制剂，所有这些特征行为都促进了内膜增生。令人惊讶的是，动脉干预后TGFß和Smad3水平升高也会产生适应性重构或血管壁扩张的有利副产物。受这些激动人心的发现的启发，我们渴望继续我们对TGFß/Smad3的研究，目标是1)进一步了解TGFß在再狭窄病理生理中的作用，2)通过操纵SMC去分化来抑制再狭窄的新策略，3)通过阻断smad依赖性和smad非依赖性TGFß信号来抑制再狭窄的治疗策略。在Specific Aim-1中，我们将剖析和区分TGFß/Smad3刺激内膜增生（促再狭窄）与适应性重塑（抗再狭窄）的途径，利用一系列产生Smad3应答基因差异表达的突变体。在Specific aim -2中，我们的目的是更好地理解TGFß/Smad3产生SMC去分化的因素，通过阻断去分化和/或增强分化可以防止内膜增生。在Specific Aim-3中，我们将确定smad非依赖性通路在TGFß诱导的再狭窄中的作用，然后设计联合疗法，同时用Smad3抑制肽阻断Smad3信号，并使用其特异性抑制剂阻断非smad通路。我们的最终目标是确定有效预防复发性血管疾病发展的药物，这一过程每年影响数十万患者。

DESCRIPTION (provided by applicant): Every year more than one million Americans require interventions to treat atherosclerotic vascular disease. Unfortunately these interventions trigger the development of recurrent disease or restenosis of the treated vessel. Although preventative therapies have been developed, restenosis still develops in 10-15% of coronary and up to 80% of lower extremity interventions (depending upon the vascular bed). Further insights into the mechanisms that underlie restenosis will aid in the development of improved therapeutics. Two major processes contribute to restenosis: 1) thickening of the neointima, termed intimal hyperplasia, and 2) changes in the vessel wall diameter resulting in either constrictive or adaptive remodeling. Our previous discoveries verify that TGFß is a dominant factor involved in both of these processes. The role of the cytokine TGFß in vascular disease has been a conundrum because of the paradox that in vitro, TGFß produces a highly differentiated smooth muscle cell (SMC) phenotype, however in vivo, TGFß stimulates SMC de-differentiation and intimal hyperplasia. We have discovered over the past grant period, a unique explanation for this conundrum: elevated levels of Smad3 that develop following vascular intervention, transform TGß into a stimulant of SMC de-differentiation, proliferation, migration and inflammation (MCP-1 production), and an inhibitor of apoptosis, all signature behaviors that promote intimal hyperplasia. Surprisingly, elevated levels of TGFß and Smad3 following arterial intervention also produce the favorable by-product of adaptive remodeling or vessel wall expansion. Inspired by these provocative findings, we are eager to continue our investigations of TGFß/Smad3 with the goal of 1) gaining further insights into TGFß's role in the pathophysiology of restenosis, 2) developing new strategies to inhibit restenosis by manipulating SMC de-differentiation and 3) developing therapeutic strategies to inhibit restenosis by blocking both Smad-dependent and Smad-independent TGFß signaling. In Specific Aim-1, we will dissect and differentiate the pathways through which TGFß/Smad3 stimulates intimal hyperplasia (pro-restenosis) versus adaptive remodeling (anti-restenosis), taking advantage of a series of mutants that produce differential expression of Smad3-responsive genes. In Specific Aim-2, we aim to better understand the factors through which TGFß/Smad3 produces SMC de- differentiation with the theory that blocking de-differentiation and/or enhancing differentiation will prevent intimal hyperplasia. In Specific Aim-3, we will determine the role of Smad-independent pathways in TGFß- induced restenosis, and then design combination therapies to simultaneously block Smad3 signaling with a Smad3-inhibiting peptide, and non-Smad pathway(s) with their specific inhibitors. Our ultimate goal is to identify agents that effectively prevent the development of recurrent vascular disease, a process affecting hundreds of thousands of patients each year.