Winslow Valeria, Vaivoda Rachel, Vasilyev Aleksandr, Dombkowski David, Douaidy Karim, Stark Christopher, Drake Justin, Guilliams Evin, Choudhary Dharamainder, Preffer Frederic, Stoilov Ivaylo, Christmas Peter
Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
Biochim Biophys Acta. 2014 Jun;1841(6):868-79. doi: 10.1016/j.bbalip.2014.03.002. Epub 2014 Mar 14.
Inflammatory responses to infection and injury must be restrained and negatively regulated to minimize damage to host tissue. One proposed mechanism involves enzymatic inactivation of the pro-inflammatory mediator leukotriene B4, but it is difficult to dissect the roles of various metabolic enzymes and pathways. A primary candidate for a regulatory pathway is omega oxidation of leukotriene B4 in neutrophils, presumptively by CYP4F3A in humans and CYP4F18 in mice. This pathway generates ω, ω-1, and ω-2 hydroxylated products of leukotriene B4, depending on species. We created mouse models targeting exons 8 and 9 of the Cyp4f18 allele that allows both conventional and conditional knockouts of Cyp4f18. Neutrophils from wild-type mice convert leukotriene B4 to 19-hydroxy leukotriene B4, and to a lesser extent 18-hydroxy leukotriene B4, whereas these products were not detected in neutrophils from conventional Cyp4f18 knockouts. A mouse model of renal ischemia-reperfusion injury was used to investigate the consequences of loss of CYP4F18 in vivo. There were no significant changes in infiltration of neutrophils and other leukocytes into kidney tissue as determined by flow cytometry and immunohistochemistry, or renal injury as assessed by histological scoring and measurement of blood urea nitrogen. It is concluded that CYP4F18 is necessary for omega oxidation of leukotriene B4 in neutrophils, and is not compensated by other CYP enzymes, but loss of this metabolic pathway is not sufficient to impact inflammation and injury following renal ischemia-reperfusion in mice.
对感染和损伤的炎症反应必须受到抑制和负调控，以尽量减少对宿主组织的损害。一种提出的机制涉及促炎介质白三烯B4的酶促失活，但难以剖析各种代谢酶和途径的作用。一种调控途径的主要候选者是中性粒细胞中白三烯B4的ω氧化，推测在人类中由CYP4F3A进行，在小鼠中由CYP4F18进行。该途径根据物种产生白三烯B4的ω、ω-1和ω-2羟基化产物。我们创建了靶向Cyp4f18等位基因外显子8和9的小鼠模型，该模型允许对Cyp4f18进行常规和条件性敲除。野生型小鼠的中性粒细胞将白三烯B4转化为19-羟基白三烯B4，并在较小程度上转化为18-羟基白三烯B4，而在常规Cyp4f18敲除小鼠的中性粒细胞中未检测到这些产物。使用肾缺血再灌注损伤小鼠模型来研究体内CYP4F18缺失的后果。通过流式细胞术和免疫组织化学测定，中性粒细胞和其他白细胞向肾组织的浸润以及通过组织学评分和血尿素氮测量评估的肾损伤均无显著变化。得出的结论是，CYP4F18对于中性粒细胞中白三烯B4的ω氧化是必需的，并且不能被其他CYP酶补偿，但这种代谢途径的缺失不足以影响小鼠肾缺血再灌注后的炎症和损伤。
