Maerki Christa, Meuter Simone, Liebi Mark, Mühlemann Kathrin, Frederick Mitchell J, Yawalkar Nikhil, Moser Bernhard, Wolf Marlene
Theodor Kocher Institute, University of Bern, Bern, Switzerland.
J Immunol. 2009 Jan 1;182(1):507-14. doi: 10.4049/jimmunol.182.1.507.
The skin is constantly exposed to commensal microflora and pathogenic microbes. The stratum corneum of the outermost skin layer employs distinct tools such as harsh growth conditions and numerous antimicrobial peptides (AMPs) to discriminate between beneficial cutaneous microflora and harmful bacteria. How the skin deals with microbes that have gained access to the live part of the skin as a result of microinjuries is ill defined. In this study, we report that the chemokine CXCL14 is a broad-spectrum AMP with killing activity for cutaneous gram-positive bacteria and Candida albicans as well as the gram-negative enterobacterium Escherichia coli. Based on two separate bacteria-killing assays, CXCL14 compares favorably with other tested AMPs, including human beta-defensin and the chemokine CCL20. Increased salt concentrations and skin-typical pH conditions did not abrogate its AMP function. This novel AMP is highly abundant in the epidermis and dermis of healthy human skin but is down-modulated under conditions of inflammation and disease. We propose that CXCL14 fights bacteria at the earliest stage of infection, well before the establishment of inflammation, and thus fulfills a unique role in antimicrobial immunity.
皮肤不断暴露于共生微生物群和致病微生物中。最外层皮肤的角质层利用诸如恶劣的生长条件和众多抗菌肽(AMPs)等独特手段来区分有益的皮肤微生物群和有害细菌。然而,对于皮肤如何应对因微损伤而进入皮肤活体部分的微生物,目前尚不清楚。在本研究中,我们报告趋化因子CXCL14是一种广谱抗菌肽,对皮肤革兰氏阳性菌、白色念珠菌以及革兰氏阴性肠道细菌大肠杆菌具有杀伤活性。基于两种独立的细菌杀伤试验,CXCL14与其他测试的抗菌肽(包括人β-防御素和趋化因子CCL20)相比表现良好。盐浓度的增加和皮肤典型的pH条件并未消除其抗菌肽功能。这种新型抗菌肽在健康人皮肤的表皮和真皮中含量丰富,但在炎症和疾病条件下会下调。我们认为,CXCL14在感染的最早阶段,即在炎症形成之前就对抗细菌,因此在抗菌免疫中发挥着独特作用。