Duffy Antigen: Modifier of Systemic and Lung Chemokine Responses in Inflammation

描述（由申请人提供）：浓缩红细胞（PRBC）输注与危重患者发病率和死亡率增加相关。这种关联的病因学尚不确定，因为白细胞减少的随机对照试验尚未令人信服地证明其临床益处。其他人假设红细胞浓缩物的非白细胞成分调节全身炎症反应，但缺乏支持合理机制的数据。Duffy抗原在红细胞和小静脉内皮上表达，结合多种趋化因子，是局部和全身炎症反应的一种潜在调节剂。我们最近发现内皮达菲抗原结合并隔离可溶性趋化因子以抑制局部组织炎症。我们还表明，红细胞达菲作为一个趋化因子水库，减少可溶性趋化因子浓度在局部组织血管床，但增加全身趋化因子的生物利用度，从而促进中性粒细胞流入肺部炎症的LPS模型中的空气空间。长期目标是更好地了解达菲如何促进趋化梯度的形成，特别是解决选择性趋化因子从肺到血管室的运动过程，并确定红细胞给药是否可以调节这一过程。我们将确定达菲是否介导选择性趋化因子动员从空气空间到血管室，以及这个过程是否涉及达菲配体内化通过小窝介导的途径在内皮细胞。我们还将确定通过PRBC输注增加Duffy结合位点是否会改变全身趋化因子浓度和嗜中性粒细胞流入发炎的肺部。我们将使用多种体外和体内方法，包括Duffy内皮转染子和caveolin-1-/-细胞来研究内化机制，Duffy敲除（dfy-/-）小鼠来研究体内趋化因子动员，和使用用DFY-/-或DFY+/+重建的辐射DFY-/-和DFY+/+小鼠的嵌合小鼠骨髓来确定内皮细胞和红细胞Duffy在体内的相对贡献。从这些研究中获得的知识可能阐明一种改变局部组织和全身炎症反应的机制，并为危重病中的常见问题提供新的见解。

DESCRIPTION (provided by applicant): Packed red blood cell (PRBC) transfusions are associated with increased morbidity and mortality in critically patients. The etiology underlying this association remains uncertain, as a clinical benefit has not been convincingly demonstrated by randomized controlled trials of leukoreduction. Others have postulated that the non-leukocyte component of red cell concentrates modulates the systemic inflammatory response, although data to support a plausible mechanism has been lacking. The Duffy antigen, expressed on erythrocytes and venular endothelium, binds multiple chemokines and is one potential modifier of local and systemic inflammatory responses. We have recently shown that endothelial Duffy antigen binds and sequesters soluble chemokines to dampen local tissue inflammation. We have also shown that erythrocyte Duffy functions as a chemokine reservoir, reducing soluble chemokine concentrations in local tissue vascular beds but increasing systemic chemokine bioavailability, thereby facilitating neutrophil influx into the airspaces in an LPS model of lung inflammation. The long-term objectives are to better understand how Duffy contributes to the formation of chemotactic gradients, specifically addressing the process of selective chemokine movement from the lungs to the vascular compartment, and determining whether erythrocyte administration can modulate this process. We will determine if Duffy mediates selective chemokine mobilization from the airspaces to the vascular compartment, and whether this process involves Duffy-ligand internalization through a caveolae-mediated pathway in endothelial cells. We will also determine whether augmenting Duffy binding sites through PRBC transfusions alters systemic chemokine concentrations and neutrophilic influx into inflamed lungs. We will use a variety of in vitro and in vivo approaches including Duffy endothelial transfectants and caveolin-1-/- cells to study the mechanism of internalization, Duffy knockout (dfy-/-) mice to study chemokine mobilization in vivo, and chimeric mice using irradiated dfy-/- and dfy+/+ mice reconstituted with dfy-/- or dfy+/+ marrow to define the relative contribution of endothelial and erythrocyte Duffy in vivo. Knowledge derived from these studies may elucidate one mechanism of modifying local tissue and systemic inflammatory responses and provide new insight to a common issue in the critically ill.