Ong Peck Y, Ohtake Takaaki, Brandt Corinne, Strickland Ian, Boguniewicz Mark, Ganz Tomas, Gallo Richard L, Leung Donald Y M
Division of Allergy and Immunology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA.
N Engl J Med. 2002 Oct 10;347(15):1151-60. doi: 10.1056/NEJMoa021481.
The innate immune system of human skin contains antimicrobial peptides known as cathelicidins (LL-37) and beta-defensins. In normal skin these peptides are negligible, but they accumulate in skin affected by inflammatory diseases such as psoriasis. We compared the levels of expression of LL-37 and human beta-defensin 2 (HBD-2) in inflamed skin from patients with atopic dermatitis and from those with psoriasis.
The expression of LL-37 and HBD-2 protein in skin-biopsy specimens from patients with psoriasis, patients with atopic dermatitis, and normal subjects was determined by immunohistochemical analysis. The amount of antimicrobial peptides in extracts of skin samples was also analyzed by immunodot blot analysis (for LL-37) and Western blot analysis (for HBD-2). Quantitative, real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assays were used to confirm the relative expression of HBD-2 and LL-37 messenger RNA (mRNA) in the skin-biopsy specimens. These peptides were also tested for antimicrobial activity against Staphylococcus aureus with the use of a colony-forming assay.
Immunohistochemical analysis confirmed the presence of abundant LL-37 and HBD-2 in the superficial epidermis of all patients with psoriasis. In comparison, immunostaining for these peptides was significantly decreased in acute and chronic lesions from patients with atopic dermatitis (P=0.006 and P=0.03, respectively). These results were confirmed by immunodot blot and Western blot analyses. Real-time RT-PCR showed significantly lower expression of HBD-2 mRNA and LL-37 mRNA in atopic lesions than in psoriatic lesions (P=0.009 and P=0.02, respectively). The combination of LL-37 and HBD-2 showed synergistic antimicrobial activity by effectively killing S. aureus.
A deficiency in the expression of antimicrobial peptides may account for the susceptibility of patients with atopic dermatitis to skin infection with S. aureus.
人类皮肤的天然免疫系统包含被称为cathelicidins（LL-37）和β-防御素的抗菌肽。在正常皮肤中，这些肽含量极少，但在诸如银屑病等炎症性疾病累及的皮肤中会积聚。我们比较了特应性皮炎患者和银屑病患者炎症皮肤中LL-37和人β-防御素2（HBD-2）的表达水平。
通过免疫组织化学分析确定银屑病患者、特应性皮炎患者和正常受试者皮肤活检标本中LL-37和HBD-2蛋白的表达。还通过免疫斑点印迹分析（用于LL-37）和蛋白质印迹分析（用于HBD-2）对皮肤样本提取物中的抗菌肽量进行分析。采用定量实时逆转录聚合酶链反应（RT-PCR）检测法来确认皮肤活检标本中HBD-2和LL-37信使核糖核酸（mRNA）的相对表达。还使用菌落形成试验检测了这些肽对金黄色葡萄球菌的抗菌活性。
免疫组织化学分析证实所有银屑病患者的浅表表皮中均存在大量LL-37和HBD-2。相比之下，特应性皮炎患者急性和慢性皮损中这些肽的免疫染色显著降低（分别为P = 0.006和P = 0.03）。免疫斑点印迹和蛋白质印迹分析证实了这些结果。实时RT-PCR显示特应性皮损中HBD-2 mRNA和LL-37 mRNA的表达明显低于银屑病皮损（分别为P = 0.009和P = 0.02）。LL-37和HBD-2联合使用通过有效杀灭金黄色葡萄球菌显示出协同抗菌活性。
抗菌肽表达不足可能是特应性皮炎患者易发生金黄色葡萄球菌皮肤感染的原因。
