School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
Peptides. 2011 Oct;32(10):1996-2002. doi: 10.1016/j.peptides.2011.08.018. Epub 2011 Aug 26.
Human cathelicidin LL37 and its fragments LL13-37 and LL17-32 exhibited similar potencies in inhibiting growth of the yeast Candida albicans. After treatment with 0.5 μM and 5 μM LL13-37, the hyphae changed from a uniformly thick to an increasingly slender appearance, with budding becoming less normal in appearance and cell death could be detected. Only the yeast form and no hyphal form could be observed following exposure to 50 μM LL13-37. LL13-37 at a concentration of 5 μM was able to permeabilize the membrane of yeast form as well as hyphal form of C. albicans since the nuclear stain SYTOX Green was localized in both forms. Mycelia treated with LL13-37 stained with SYTOX Green, but did not stain with MitoTracker deep red, indicating that the mitochondria were adversely affected by LL13-37. Bimane-labeled LL13-37 was able to enter some of the hyphae, but not all hyphae were affected, suggesting that LL37 impaired membrane permeability characteristics in some of the hyphae. Reactive oxygen species was detectable in the yeast form of C. albicans cells after treatment with LL13-37 but not in the untreated cells. The results suggest that the increased membrane permeability caused by LL13-37 might not be the sole cause of cell death. It might lead to the uptake of the peptide, which might have some intracellular targets.
人源杀菌肽 LL37 及其片段 LL13-37 和 LL17-32 对白色念珠菌的生长均具有相似的抑制作用。用 0.5μM 和 5μM 的 LL13-37 处理后，菌丝由均匀厚壁变为越来越细，出芽外观变得不太正常，可检测到细胞死亡。暴露于 50μM 的 LL13-37 后，只能观察到酵母形态，而无菌丝形态。浓度为 5μM 的 LL13-37 能够使白色念珠菌的酵母形态和菌丝形态的细胞膜通透性增加，因为核染料 SYTOX Green 定位于这两种形态中。用 SYTOX Green 染色处理的菌丝，但用 MitoTracker deep red 不染色，表明线粒体受到 LL13-37 的不利影响。双马来酰亚胺标记的 LL13-37 能够进入一些菌丝，但并非所有菌丝都受到影响，表明 LL37 破坏了一些菌丝的膜通透性特征。在用 LL13-37 处理后，白色念珠菌酵母细胞中可检测到活性氧，但未经处理的细胞中则没有。结果表明，LL13-37 引起的细胞膜通透性增加可能不是细胞死亡的唯一原因。这可能导致肽的摄取，而肽可能有一些细胞内靶标。
