Department of Life Science, College of Natural Science, Daejin University, Pocheon, Gyeonggido, South Korea.
Antimicrob Agents Chemother. 2011 Oct;55(10):4850-7. doi: 10.1128/AAC.00177-11. Epub 2011 Aug 1.
Clostridium difficile-associated diarrhea and pseudomembranous colitis are typically treated with vancomycin or metronidazole, but recent increases in relapse incidence and the emergence of drug-resistant strains of C. difficile indicate the need for new antibiotics. We previously isolated coprisin, an antibacterial peptide from Copris tripartitus, a Korean dung beetle, and identified a nine-amino-acid peptide in the α-helical region of it (LLCIALRKK) that had antimicrobial activity (J.-S. Hwang et al., Int. J. Pept., 2009, doi:10.1155/2009/136284). Here, we examined whether treatment with a coprisin analogue (a disulfide dimer of the nine peptides) prevented inflammation and mucosal damage in a mouse model of acute gut inflammation established by administration of antibiotics followed by C. difficile infection. In this model, coprisin treatment significantly ameliorated body weight decreases, improved the survival rate, and decreased mucosal damage and proinflammatory cytokine production. In contrast, the coprisin analogue had no apparent antibiotic activity against commensal bacteria, including Lactobacillus and Bifidobacterium, which are known to inhibit the colonization of C. difficile. The exposure of C. difficile to the coprisin analogue caused a marked increase in nuclear propidium iodide (PI) staining, indicating membrane damage; the staining levels were similar to those seen with bacteria treated with a positive control for membrane disruption (EDTA). In contrast, coprisin analogue treatment did not trigger increases in the nuclear PI staining of Bifidobacterium thermophilum. This observation suggests that the antibiotic activity of the coprisin analogue may occur through specific membrane disruption of C. difficile. Thus, these results indicate that the coprisin analogue may prove useful as a therapeutic agent for C. difficile infection-associated inflammatory diarrhea and pseudomembranous colitis.
艰难梭菌相关性腹泻和伪膜性结肠炎通常采用万古霉素或甲硝唑治疗，但最近复发率的增加和艰难梭菌耐药菌株的出现表明需要新的抗生素。我们之前从韩国蜣螂（Copris tripartitus）中分离出一种抗菌肽Coprisin，并鉴定出其α-螺旋区域中的一个九肽（LLCIALRKK）具有抗菌活性（J.-S. Hwang 等人，国际肽杂志，2009 年，doi:10.1155/2009/136284）。在这里，我们研究了一种 Coprisin 类似物（九肽的二硫键二聚体）是否能预防抗生素治疗后继发艰难梭菌感染引起的急性肠道炎症小鼠模型中的炎症和粘膜损伤。在该模型中，Coprisin 治疗显著改善了体重下降，提高了存活率，并减少了粘膜损伤和促炎细胞因子的产生。相比之下，Coprisin 类似物对包括乳酸杆菌和双歧杆菌在内的共生菌没有明显的抗生素活性，已知这些细菌能抑制艰难梭菌的定植。Coprisin 类似物暴露于艰难梭菌会导致核碘化丙啶（PI）染色明显增加，表明膜损伤；染色水平与用膜破坏阳性对照物（EDTA）处理的细菌相似。相比之下，Coprisin 类似物处理不会引发双歧杆菌核 PI 染色的增加。这一观察结果表明，Coprisin 类似物的抗生素活性可能通过艰难梭菌的特定膜破坏来实现。因此，这些结果表明 Coprisin 类似物可能可用于治疗艰难梭菌感染相关性炎症性腹泻和伪膜性结肠炎。
