Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
J Innate Immun. 2010;2(6):508-21. doi: 10.1159/000317665. Epub 2010 Sep 4.
Neutrophil-derived antimicrobial peptides and proteins (AMPs) play an important role in the defense against microbes. Absence of defense is illustrated by neutropenic patients with frequent bacterial and fungal infections. However, the specificity of the antimicrobial effects has not been adequately described. We set out to determine the specific antimicrobial pattern of polypeptides in neutrophils (polymorphonuclear leukocytes, PMNs) against 4 potential human pathogens: Moraxella catarrhalis, Staphylococcus aureus, Haemophilus influenzae and Candida albicans. Protein extracts of human PMNs were separated using high-performance liquid chromatography and fractions were assayed for antimicrobial activity. Fractions displaying antimicrobial activity were separated on SDS-PAGE and characterized using MALDI-MS. Depletion experiments were utilized to determine the contribution of each AMP to the antimicrobial effect. Among the identified AMPs, α-defensins 1-3, azurocidin, LL-37, lysozyme, calprotectin and lactotransferrin were studied in detail. We found a divergent pattern of killing, that is, certain peptides and proteins exhibited selective activity against specific pathogens, while others displayed a broader antimicrobial activity. α-Defensins, LL-37 and calprotectin were active against all species, while lactotransferrin exclusively inhibited growth of S. aureus. Conversely, azurocidin was active against all species except S. aureus. Our observations may shed light on bacterial resistance to AMPs and on the elimination of specific bacterial communities on mucosal surfaces.
中性粒细胞衍生的抗菌肽和蛋白（AMPs）在抵御微生物方面发挥着重要作用。中性粒细胞减少症患者经常发生细菌和真菌感染，表明其防御功能缺失。然而，抗菌作用的特异性尚未得到充分描述。我们着手确定中性粒细胞（多形核白细胞，PMN）中多肽针对 4 种潜在人类病原体的特定抗菌模式：卡他莫拉菌、金黄色葡萄球菌、流感嗜血杆菌和白色念珠菌。使用高效液相色谱法分离人 PMN 的蛋白质提取物，并测定抗菌活性的分数。显示抗菌活性的分数在 SDS-PAGE 上分离，并使用 MALDI-MS 进行表征。利用耗竭实验来确定每种 AMP 对抗菌作用的贡献。在所鉴定的 AMP 中，α-防御素 1-3、天青杀素、LL-37、溶菌酶、钙卫蛋白和乳转铁蛋白被详细研究。我们发现了一种不同的杀伤模式，即某些肽和蛋白对特定病原体表现出选择性活性，而其他则表现出更广泛的抗菌活性。α-防御素、LL-37 和钙卫蛋白对所有物种均有活性，而乳转铁蛋白仅抑制金黄色葡萄球菌的生长。相反，天青杀素对所有物种均有活性，除了金黄色葡萄球菌。我们的观察结果可能揭示了细菌对 AMP 的耐药性以及在黏膜表面消除特定细菌群落的机制。
