The Role of Vascular Calprotectin in Arteriovenous Fistula Maturation

超过600,000名美国人患有终末期肾病，其中∼468,000人是依赖功能性血管通路延长生命的透析患者。成熟的动静脉(A-V)瘘是首选的透析途径，因为与合成移植物和中心静脉导管相比，它具有更高的通畅率和更低的医疗成本。然而，约40%的新形成的瘘管无法成熟，即它们不能用于透析，因为狭窄阻碍了它们达到必要的血流。尽管动静脉瘘术后狭窄对患者的发病率、死亡率和生活质量有负面影响，但对其发生机制的研究还很少。这一翻译建议建立了CXCL12和PU.1/钙保护素信号网络、向内重构和瘘管结局之间的机制关系，以便设计有针对性的治疗方法来防止成熟失败。我们的建议建立在强有力的科学前提之上，表明转录因子PU.1的异位表达导致的动静脉瘘术后钙保护素的积聚与导致瘘管失败的向内重构之间存在机械关系。我们的主要假设是，平滑肌细胞(SMC)衍生的钙保护素增加了新形成的动静脉瘘狭窄和失败的风险。我们的机制假设是，血液透析患者CXCL12水平升高导致PU.1在血管系统中异位表达，并随后在SMC中积聚钙保护素。钙保护素的释放加剧了瘘管形成后的炎症、纤维化和内膜增生(IH)。我们将在三个特定的目标和五个实验布局中检验我们的假设，这将证明：1)钙保护素对瘘管向内重塑的贡献；2)CXCL12和PU.1增加钙保护素和动静脉瘘失败风险的潜在机制；以及3)PU.1与人类队列中瘘管成熟结局的关系。我们将结合精细的显微外科技术和基因敲除小鼠来成功实现我们的目标。我们还将询问随机选择的100名患者的人体生物库，以寻找静脉重塑后PU1水平与不成熟之间的联系。总之，随着这一提议的成功完成，我们正在为设计新的药物和针对细胞类型的干预措施铺平道路，以有效地针对动静脉瘘纤维化和IH，并减少血管通路并发症。

Over 600,000 Americans live with end-stage renal disease (ESRD), and ∼468,000 of them are dialysis patients who depend on a functional vascular access to extend their lives. A mature arteriovenous (A-V) fistula is the preferred dialysis access due to its higher patency rates and lower medical costs compared to synthetic grafts and central venous catheters. However, ~40% of newly created fistulas fail to mature, i.e., they are not usable for dialysis because stenosis prevents them from reaching the necessary blood flow. There is paucity of research into the mechanisms underlying postoperative stenosis in A-V fistulas, despite its negative impact on morbidity, mortality, and quality of life of these patients. This translational proposal establishes the mechanistic relationship among the CXCL12 and PU.1/calprotectin signaling network, inward remodeling, and fistula outcomes in order to design targeted therapies to prevent maturation failure. Our proposal is built on strong scientific premises that suggest a mechanistic relationship between postoperative accumulation of calprotectin in A-V fistulas caused by ectopic expression of the transcription factor PU.1 and inward remodeling that causes fistula failure. Our overarching hypothesis is that smooth muscle cell (SMC)-derived calprotectin increases the risk for stenosis and failure in newly created A-V fistulas. Our mechanistic hypothesis is that elevated CXCL12 level in hemodialysis patients leads to ectopic expression of PU.1 in the vasculature and the subsequent accumulation of calprotectin in SMCs. The released calprotectin exacerbates inflammation, fibrosis, and intimal hyperplasia (IH) after fistula creation. We will test our hypothesis in three specific aims and five experimental layouts that will prove: 1) the contribution of calprotectin to fistula inward remodeling; 2) the underlying mechanisms by which CXCL12 and PU.1 increases calprotectin and the risk of A-V fistula failure; and 3) the relationship between PU.1 and fistula maturation outcomes in a human cohort. We will combine fine microsurgical techniques and knockout mice to successfully achieve our goals. We will also interrogate a human biorepository of 100 randomly selected patients undergoing creation of two-stage brachiobasilic transposition fistulas to search for associations between the levels of PU.1 after venous remodeling and inadequate maturation. In conclusion, with the successful accomplishment of this proposal, we are paving the way for the design of new drugs and cell type-specific interventions to effectively target A-V fistula fibrosis and IH and reduce vascular access complications.