Wang Tao, Cunningham Alexis, Dokun Ayotunde O, Hazarika Surovi, Houston Kevin, Chen Lingdan, Lye R John, Spolski Rosanne, Leonard Warren J, Annex Brian H
From the Robert M. Berne Cardiovascular Research Center (T.W., A.C., A.O.D., S.H., K.H., L.C., R.J.L., B.H.A.) and Division of Cardiovascular Medicine, Department of Medicine (S.H., B.H.A.), University of Virginia, Charlottesville; and Laboratory of Molecular Immunology and the Immunology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD (R.S., W.J.L.).
Arterioscler Thromb Vasc Biol. 2015 May;35(5):1218-25. doi: 10.1161/ATVBAHA.115.305476. Epub 2015 Apr 2.
Surgical hindlimb ischemia (HLI) in mice has become a valuable preclinical model to study peripheral arterial disease. We previously identified that the different phenotypic outcomes after HLI across inbred mouse strains is related to a region on the short arm of mouse chromosome 7. The gene coding the interleukin-21 receptor (IL-21R) lies at the peak of association in this region.
With quantitative real-time polymerase chain reaction, we found that a mouse strain with a greater ability to upregulate IL-21R after HLI had better perfusion recovery than a strain with no upregulation after HLI. Immunofluorescent staining of ischemic hindlimb tissue showed IL-21R expression on endothelial cells (ECs) from C57BL/6 mice. An EC-enriched fraction isolated from ischemic hindlimb muscle showed higher Il-21R levels than an EC-enriched fraction from nonischemic limbs. In vitro, human umbilical vein ECs showed elevated IL-21R expression after hypoxia and serum starvation. Under these conditions, IL-21 treatment increased cell viability, decreased cell apoptosis, and augmented tube formation. In vivo, either knockout Il21r or blocking IL-21 signaling by treating with IL-21R-Fc (fusion protein that blocks IL-21 binding to its receptor) in C57BL/6 mice resulted in less perfusion recovery after HLI. Both in vitro and in vivo modulation of the IL-21/IL-21R axis under hypoxic conditions resulted in increased signal transducer and activator of transcription 3 phosphorylation and a subsequent increase in the B-cell lymphoma leukemia-2/BCL-2-associated X protein ratio.
Our data indicate that IL-21R upregulation and ligand activation in hypoxic ECs may help perfusion recovery by limiting/preventing apoptosis and favoring cell survival and angiogenesis through the signal transducer and activator of transcription 3 pathway.
小鼠手术性后肢缺血（HLI）已成为研究外周动脉疾病的一种有价值的临床前模型。我们之前发现，近交系小鼠品系在HLI后不同的表型结果与小鼠7号染色体短臂上的一个区域有关。编码白细胞介素21受体（IL-21R）的基因位于该区域的关联峰值处。
通过定量实时聚合酶链反应，我们发现HLI后上调IL-21R能力较强的小鼠品系比HLI后无上调的品系具有更好的灌注恢复。缺血后肢组织的免疫荧光染色显示C57BL/6小鼠内皮细胞（ECs）上有IL-21R表达。从缺血后肢肌肉分离的富含EC的部分显示出比非缺血肢体的富含EC的部分更高的Il-21R水平。在体外，人脐静脉ECs在缺氧和血清饥饿后显示出IL-21R表达升高。在这些条件下，IL-21处理增加了细胞活力，减少了细胞凋亡，并增强了管腔形成。在体内，敲除Il21r或在C57BL/6小鼠中用IL-21R-Fc（阻断IL-21与其受体结合的融合蛋白）处理阻断IL-21信号传导，导致HLI后灌注恢复较差。在缺氧条件下对IL-21/IL-21R轴进行体外和体内调节均导致信号转导和转录激活因子3磷酸化增加，随后B细胞淋巴瘤白血病-2/BCL-2相关X蛋白比值增加。
我们的数据表明，缺氧ECs中IL-21R的上调和配体激活可能通过限制/预防细胞凋亡，并通过信号转导和转录激活因子3途径促进细胞存活和血管生成，从而有助于灌注恢复。
