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

描述(由申请人提供)：在危重患者中，输注红细胞(PRBC)会增加发病率和死亡率。这种联系背后的病因仍然不确定，因为临床益处还没有被白细胞减少的随机对照试验令人信服地证明。其他人推测，红细胞浓缩物的非白细胞成分调节全身炎症反应，尽管缺乏数据支持合理的机制。Duffy抗原表达于红细胞和静脉内皮细胞，结合多种趋化因子，是局部和全身炎症反应的潜在修饰物。我们最近发现内皮Duffy抗原结合和隔离可溶性趋化因子来抑制局部组织炎症。我们还表明，红细胞Duffy作为趋化因子储存库，降低局部组织血管床中的可溶性趋化因子浓度，但增加全身趋化因子的生物利用度，从而促进中性粒细胞在内毒素肺炎症模型中进入空气空间。长期目标是更好地了解达菲如何促进趋化梯度的形成，特别是研究趋化因子从肺到血管腔的选择性移动过程，并确定红细胞给药是否可以调节这一过程。我们将确定Duffy是否介导选择性趋化因子从空气到血管腔的动员，以及这一过程是否涉及通过小窝介导的内皮细胞内化Duffy配体的途径。我们还将确定通过输注PRBC增加Duffy结合位点是否改变全身趋化因子浓度和中性粒细胞进入炎症肺的情况。我们将使用多种体外和体内方法，包括Duffy内皮转染体和小凹-1-/-细胞来研究内化机制，Duffy基因敲除(dfy-/-)小鼠来研究体内趋化因子的动员，嵌合体小鼠使用辐射后的dfy-/-和dfy+/+小鼠来确定内皮细胞和红细胞Duffy在体内的相对贡献。来自这些研究的知识可能阐明改变局部组织和全身炎症反应的一种机制，并为危重患者的共同问题提供新的见解。

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.