The Multiple Roles of Lysyl Oxidase in Arteriovenous Fistula Failure

超过14000名登记的退伍军人依靠动静脉瘘或其他类型的血管 获得血液透析并延长生命。静脉转变为瘘管是 最有趣的过程。理想的情况是瘘管成熟成为一个 血管更大，管腔面积增加，管壁更厚。不幸的是，动静脉瘘经常失败（约40%） 因为静脉狭窄会影响血流我们最近发现狭窄的发生是由于 过度的中膜纤维化，并因内膜增生（IH）而加重。我们的目标是证明 在动静脉瘘的静脉分支中上调的赖氨酰氧化酶（LOX）介导了不适当的细胞外 基质（ECM）重塑和内膜的病理性扩张，这导致狭窄和衰竭。这 该提案建立了LOX和瘘管结果之间的因果关系， 靶向治疗。我们的建议是建立在强大的科学前提（手稿和独特的初步 数据），表明自体瘘管中LOX的术后上调与 以及导致瘘管失败的不适当的重塑具体来说，我们假设LOX破坏了 表观遗传标记，确保平滑肌细胞（SMC）中的收缩基因表达，从而促进 新创建的动静脉瘘的SMC表型转变、新生内膜形成和纤维化。我们也 我假设细胞外LOX同时增加硬度和改变胶原结构， 血管通路的类型。我们将在三个具体目标和五个实验布局中测试我们的假设 这将证明：1）血管LOX在术后动静脉瘘狭窄中的作用; 2）LOX在 瘘形成后SMC表型的表观遗传控制; 3）前- 人类队列中现有LOX和A-V瘘结局。我们将使用精细的显微外科技术， 新型条件性基因敲除小鼠以及体外和原位模型，以成功实现我们的目标。我们将 我还询问了一个超过300名患者的人类生物储存库， 易位瘘，以寻找LOX水平和成熟失败之间的关联。在 最后，随着这一提案的成功完成，我们正在为设计 有效靶向动静脉瘘纤维化和减少血管性纤维化的新药和细胞类型特异性干预 入路并发症。

More than 14 000 enrolled veterans depend on an arteriovenous (A-V) fistula or other type of vascular access to receive hemodialysis and prolong their lives. The transformation of a vein to a fistula is one of the most intriguing processes in vascular biology. The desired scenario is that the fistula matures becoming a larger vessel with increased luminal area and a thicker wall. Unfortunately, A-V fistulas frequently fail (~40%) because venous stenosis compromises blood flow. We recently discovered that stenosis occurs due to excessive medial fibrosis, and is aggravated by intimal hyperplasia (IH). Our specific goal is to demonstrate that up-regulated lysyl oxidase (LOX) in the venous limb of the A-V fistula mediates improper extracellular matrix (ECM) remodeling and pathological expansion of the intima, which causes stenosis and failure. This proposal establishes the cause- effect relationship among LOX and fistula outcomes in order to design targeted therapies. Our proposal is built on strong scientific premises (manuscripts and unique preliminary data) that suggest a mechanistic relationship between postoperative upregulation of LOX in native fistulas and the improper remodeling that causes fistula failure. Specifically, we hypothesize that LOX disrupts the epigenetic marks that secure contractile gene expression in smooth muscle cells (SMC), thereby facilitating the phenotypic switch of SMCs, neointima formation, and fibrosis of newly created A-V fistulas. We also postulate that extracellular LOX simultaneously increases stiffness and altered collagen configuration in this type of vascular access. We will test our hypothesis in three specific aims and five experimental layouts that will prove: 1) the contribution of vascular LOX to postoperative A-V fistula stenosis; 2) the role of LOX in the epigenetic control of the SMC phenotype after fistula creation; and 3) the relationship between pre- existing LOX and A-V fistula outcomes in a human cohort. We will use fine microsurgical techniques in a novel conditional knockout mice and in vitro and in situ models to successfully achieve our goals. We will also interrogate a human biorepository of >300 patients undergoing creation of a two- stage brachiobasilic transposition fistula to search for associations between the levels of LOX and maturation failure. 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 reduce vascular access complications.