Department of Medicine, Boston University School of Medicine, Massachusetts, USA.
Innate Immun. 2010 Jun;16(3):151-9. doi: 10.1177/1753425910365734. Epub 2010 Apr 23.
Defensins were first identified in 1985 and are now recognized as part of a large family of antimicrobial peptides, divided into three categories: alpha-, beta-, and -defensins. These defensin classes differ in structure, sites of expression and biological activities. Human alpha-defensins include peptides that are expressed primarily in neutrophils, whereas human beta-defensins are widely expressed in epithelial cells, including those lining the respiratory tract. Defensins were first studied for their broad spectrum activity against bacteria, fungi and viruses; however, it is now clear that they also recruit inflammatory cells and promote innate and adaptive immune responses. Recent evidence shows that defensins have anti-inflammatory effects as well. Hence, defensins can participate in all phases of an immune response in the lung, including initial killing of pathogens and mounting - and resolution -- of an immune or inflammatory response. The cathelicidin, LL-37, is an antimicrobial peptide produced by neutrophils and respiratory epithelial cells that has similar roles in lung immunity as the defensins. A major challenge for the coming years will be to sort out the relative contributions of defensins and LL-37 to overall immune responses in the lung and to determine which of their many in vitro activities are most important for lung immunity.
防御素于 1985 年首次被发现，现已被认为是一大类抗菌肽的组成部分，可分为三类：α-、β-和 -防御素。这些防御素在结构、表达部位和生物学活性上有所不同。人类α-防御素包括主要在中性粒细胞中表达的肽，而人类β-防御素则广泛表达于上皮细胞，包括呼吸道上皮细胞。防御素最初因其对细菌、真菌和病毒的广谱活性而被研究；然而，现在很清楚，它们还招募炎症细胞，并促进先天和适应性免疫反应。最近的证据表明，防御素也具有抗炎作用。因此，防御素可以参与肺部免疫反应的所有阶段，包括最初杀死病原体以及启动和解决免疫或炎症反应。抗菌肽 LL-37 是一种由中性粒细胞和呼吸道上皮细胞产生的抗菌肽，它在肺部免疫中具有与防御素相似的作用。未来几年的主要挑战将是理清防御素和 LL-37 对肺部整体免疫反应的相对贡献，并确定它们众多体外活性中哪些对肺部免疫最重要。
