Yang Zequan, Sharma Ashish K, Linden Joel, Kron Irving L, Laubach Victor E
Department of Surgery, University of Virginia Health System, Charlottesville, VA 22908, USA.
J Thorac Cardiovasc Surg. 2009 Mar;137(3):695-702; discussion 702. doi: 10.1016/j.jtcvs.2008.10.044.
Postischemic reperfusion of the lung triggers proinflammatory responses that stimulate injurious neutrophil chemotaxis. We hypothesized that T lymphocytes are recruited and activated during reperfusion and mediate subsequent neutrophil-induced lung ischemia-reperfusion injury.
An in vivo mouse model of lung ischemia-reperfusion injury was used. C57BL/6 mice were assigned to either the sham group (left thoracotomy) or 7 study groups that underwent 1-hour left hilar occlusion followed by 1 to 24 hours of reperfusion. After in vivo reperfusion, the lungs were perfused ex vivo with buffer whereby pulmonary function was assessed. Lung vascular permeability, edema, neutrophil accumulation, and cytokine/chemokine production (tumor necrosis factor alpha, interleukin 17, CCL3, and CXCL1) were assessed based on Evans blue dye leak, wet/dry weight ratio, myeloperoxidase level, and enzyme-linked immunosorbent assay, respectively.
A preliminary study showed that 2 hours of reperfusion resulted in greater pulmonary dysfunction than 1 or 24 hours of reperfusion. The 2-hour reperfusion period was thus used for the remaining experiments. Comparable and significant protection from ischemia-reperfusion injury-induced lung dysfunction and injury occurred after antibody depletion of neutrophils or CD4(+) T cells but not CD8(+) T cells (P < .05 vs immunoglobulin G control). Lung ischemia-reperfusion injury was proportional to the infiltration of neutrophils but not T cells. Moreover, pulmonary neutrophil infiltration and the production of CXCL1 (KC) were significantly diminished by CD4(+) T-cell depletion but not vice versa.
Both CD4(+) T lymphocytes and neutrophils accumulate during reperfusion and contribute sequentially to lung ischemia-reperfusion injury. The data suggest that neutrophils mediate ischemia-reperfusion injury; however, CD4(+) T cells play a critical role in stimulating chemokine production and neutrophil chemotaxis during ischemia-reperfusion injury.
肺缺血后再灌注会引发促炎反应，刺激有害的中性粒细胞趋化。我们假设T淋巴细胞在再灌注期间被募集并激活，并介导随后中性粒细胞诱导的肺缺血-再灌注损伤。
采用体内小鼠肺缺血-再灌注损伤模型。将C57BL/6小鼠分为假手术组（左胸切开术）或7个研究组，后者经历1小时左肺门阻断，随后再灌注1至24小时。体内再灌注后，用缓冲液对肺进行离体灌注，从而评估肺功能。分别基于伊文思蓝染料渗漏、湿/干重比、髓过氧化物酶水平和酶联免疫吸附测定，评估肺血管通透性、水肿、中性粒细胞积聚以及细胞因子/趋化因子产生（肿瘤坏死因子α、白细胞介素17、CCL3和CXCL1）。
一项初步研究表明，与1小时或24小时再灌注相比，2小时再灌注导致更严重的肺功能障碍。因此，在其余实验中采用2小时再灌注期。在对中性粒细胞或CD4(+) T细胞进行抗体清除后，对缺血-再灌注损伤诱导的肺功能障碍和损伤有类似且显著的保护作用，但对CD8(+) T细胞清除后则无此作用（与免疫球蛋白G对照相比，P < .05）。肺缺血-再灌注损伤与中性粒细胞浸润成正比，但与T细胞浸润无关。此外，CD4(+) T细胞清除可显著减少肺中性粒细胞浸润和CXCL1（KC）产生，但反之则不然。
CD4(+) T淋巴细胞和中性粒细胞在再灌注期间均会积聚，并依次导致肺缺血-再灌注损伤。数据表明中性粒细胞介导缺血-再灌注损伤；然而，CD4(+) T细胞在缺血-再灌注损伤期间刺激趋化因子产生和中性粒细胞趋化方面发挥关键作用。
