Okrent D G, Lichtenstein A K, Ganz T
Will Rogers Institute Pulmonary Research Laboratory, Department of Medicine, UCLA School of Medicine.
Am Rev Respir Dis. 1990 Jan;141(1):179-85. doi: 10.1164/ajrccm/141.1.179.
Neutrophils, in the course of defending the host against microbial invasion, release a potent arsenal of proteins that can potentially damage host tissues. Defensins are major peptides of human polymorphonuclear leukocyte (PMN) granules and are both broadly microbicidal and cytotoxic to several tumor cell lines. To determine whether these peptides could play a role in neutrophil-mediated lung injury, we examined the cytotoxicity of defensins and other PMN granule proteins in a chromium release assay with human lung-derived cell lines MRC-5 (lung fetal fibroblast), A549 (lung adenocarcinoma with features of alveolar epithelium), and primary cultures of human umbilical vein endothelial cells (HUVEC). Crude fractionation of an acid extract of human PMN granules yielded four fractions A-D. Only fraction D (containing mostly defensins) was significantly cytotoxic to all three target cells. In contrast, fraction A (containing myeloperoxidase and lactoferrin) and fraction C (containing lysozyme) had little effect, and fraction B (containing chiefly cathepsin G and elastase) was only injurious to endothelial cells. The cytotoxicity of whole PMN granule extracts on pulmonary epithelial and fibroblast targets could be completely accounted for by their defensin content. Fraction D- and defensin-mediated cytotoxicity was concentration dependent, required at least 10 to 12 h to become manifest, and was inhibited by serum. The role of these peptides in lung damage during acute and chronic inflammation deserves further study.
在抵御微生物入侵以保护宿主的过程中，中性粒细胞会释放一系列可能损害宿主组织的蛋白质。防御素是人类多形核白细胞（PMN）颗粒中的主要肽类，对多种肿瘤细胞系具有广泛的杀菌和细胞毒性作用。为了确定这些肽是否在中性粒细胞介导的肺损伤中发挥作用，我们在一项铬释放试验中，检测了防御素和其他PMN颗粒蛋白对源自人肺的细胞系MRC-5（肺胎儿成纤维细胞）、A549（具有肺泡上皮特征的肺腺癌）以及人脐静脉内皮细胞（HUVEC）原代培养物的细胞毒性。对人PMN颗粒的酸提取物进行粗分级分离得到四个组分A - D。只有组分D（主要含有防御素）对所有三种靶细胞具有显著的细胞毒性。相比之下，组分A（含有髓过氧化物酶和乳铁蛋白）和组分C（含有溶菌酶）影响很小，而组分B（主要含有组织蛋白酶G和弹性蛋白酶）仅对内皮细胞有损伤作用。整个PMN颗粒提取物对肺上皮和成纤维细胞靶标的细胞毒性完全可由其防御素含量来解释。组分D和防御素介导的细胞毒性呈浓度依赖性，至少需要10至12小时才会显现，并且会受到血清的抑制。这些肽在急性和慢性炎症期间肺损伤中的作用值得进一步研究。
