Hwaiz Rundk, Rahman Milladur, Zhang Enming, Thorlacius Henrik
Department of Clinical Sciences, Malmö, Section for Surgery, Lund University, Malmö, Sweden.
Islet Pathophysiology, Lund University, Malmö, Sweden.
Br J Pharmacol. 2015 Nov;172(22):5347-59. doi: 10.1111/bph.13325. Epub 2015 Oct 24.
Platelets are potent regulators of neutrophil accumulation in septic lung damage. We hypothesized that platelet-derived CXCL4 might support pulmonary neutrophilia in a murine model of abdominal sepsis.
Polymicrobial sepsis was triggered by coecal ligation and puncture (CLP) in C57BL/6 mice. Platelet secretion of CXCL4 was studied by using confocal microscopy. Plasma and lung levels of CXCL4, CXCL1 and CXCL2 were determined by elisa. Flow cytometry was used to examine surface expression of Mac-1 on neutrophils.
CLP increased CXCL4 levels in plasma, and platelet depletion reduced plasma levels of CXCL4 in septic animals. Rac1 inhibitor NSC23766 decreased the CLP-enhanced CXCL4 in plasma by 77%. NSC23766 also abolished PAR4 agonist-induced secretion of CXCL4 from isolated platelets. Inhibition of CXCL4 reduced CLP-evoked neutrophil recruitment, oedema formation and tissue damage in the lung. However, immunoneutralization of CXCL4 had no effect on CLP-induced expression of Mac-1 on neutrophils. Targeting CXCL4 attenuated plasma and lung levels of CXCL1 and CXCL2 in septic mice. CXCL4 had no effect on neutrophil chemotaxis in vitro, indicating it has an indirect effect on pulmonary neutrophilia. Intratracheal CXCL4 enhanced infiltration of neutrophils and formation of CXCL2 in the lung. CXCR2 antagonist SB225002 markedly reduced CXCL4-provoked neutrophil accumulation in the lung. CXCL4 caused secretion of CXCL2 from isolated alveolar macrophages.
Rac1 controls platelet secretion of CXCL4 and CXCL4 is a potent stimulator of neutrophil accumulation in septic lungs via generation of CXCL2 in alveolar macrophages. Platelet-derived CXCL4 plays an important role in lung inflammation and tissue damage in polymicrobial sepsis.
血小板是脓毒症肺损伤中中性粒细胞聚集的有效调节因子。我们推测，在腹部脓毒症小鼠模型中，血小板衍生的CXCL4可能会促进肺部中性粒细胞增多。
通过对C57BL/6小鼠进行盲肠结扎和穿刺（CLP）诱导多微生物脓毒症。使用共聚焦显微镜研究CXCL4的血小板分泌情况。通过酶联免疫吸附测定法（ELISA）测定血浆和肺组织中CXCL4、CXCL1和CXCL2的水平。使用流式细胞术检测中性粒细胞表面Mac-1的表达。
CLP增加了血浆中CXCL4的水平，血小板耗竭降低了脓毒症动物血浆中CXCL4的水平。Rac1抑制剂NSC23766使CLP增强的血浆中CXCL4水平降低了77%。NSC23766还消除了PAR4激动剂诱导的分离血小板中CXCL4的分泌。抑制CXCL4可减少CLP诱发的中性粒细胞募集、肺水肿形成和肺组织损伤。然而，CXCL4的免疫中和对CLP诱导的中性粒细胞上Mac-1的表达没有影响。靶向CXCL4可降低脓毒症小鼠血浆和肺组织中CXCL1和CXCL2的水平。CXCL4在体外对中性粒细胞趋化性没有影响，表明它对肺部中性粒细胞增多有间接作用。气管内注射CXCL4可增强肺部中性粒细胞浸润和CXCL2的形成。CXCR2拮抗剂SB225002显著减少了CXCL4引起的肺部中性粒细胞聚集。CXCL4导致分离的肺泡巨噬细胞分泌CXCL2。
Rac1控制血小板CXCL4的分泌，CXCL4通过在肺泡巨噬细胞中生成CXCL2，成为脓毒症肺中中性粒细胞聚集的有效刺激因子。血小板衍生的CXCL4在多微生物脓毒症的肺部炎症和组织损伤中起重要作用。
