Susceptibility of human and murine Chlamydia trachomatis serovars to granulocyte‐ and epithelium‐derived antimicrobial peptides

Abstract: Four antimicrobial peptides, protegrin‐1, RTD‐1, cryptdin‐4, and indolicidin, were tested for their ability to inhibit the in vitro growth of Chlamydia trachomatis serovars E, L2, and mouse pneumonitis (MoPn). In general, protegrin‐1 was found to have the strongest anti‐chlamydial activity. Overall, of the three serovars tested, L2 was the most susceptible while MoPn was the most resistant to these peptides.     

Killing of Fusobacterium nucleaturn,Porphyromonas gingivalis and Prevotella intermedia by protegrins

Protegrins are broad spectrum antibiotic peptides isolated from porcine leukocytes. In this study, we (i) examine the sensitivity of Gram-negative, anaerobic periodontal pathogens to synthetic protegrins; (ii) determine the relative potencies of protegrin congeners against these bacteria; and (iii) compare the potency of protegrins with other antibiotic peptides, including magainin MSI-78, tachyplesin I, cecropin P1, human defensins HNP-1-3, and clavanin A. Synthetic l - and d -enantiomers of protegrin 1 (PG-1 and D-PG-1, respectively), and L-enantiomers of protegrins 2, 3 and 5 (PG-2, PG-3 and PG-5) were tested against Fusobacteriurn nucleatum, and black-pigmented organisms including Porphyromonas gingivalis and Prevotella intermedia. Strains of both F. nucleatum and the black-pigmented organisms were sensitive to PG-1, and exhibited mean ED₉₉ of 2.2-2.3 μg/ml and 3.4-9.9 μg/ml, respectively. The D-form was statistically more potent than the L-form against these oral anaerobes, and although this difference in potency is unlikely to be of decisive therapeutic significance, the d -form may be of value given ability to resist microbial and host-derived proteases. PG-1 was more potent than magainin, tachyplesin, cecropin, defensins and clavanin under test conditions. Hypertonic saIt concentrations and heat-inactivated serum were found to be inhibitory to the bactericidal activity of PG-1. PG-1 was found to induce morphologic alterations in the ultrastructural appearance of F. nucleatum consistent with damage to the bacterial membranes. We conclude that protegrins may be useful antimicrobial agents in therapy against Gram-negative anaerobic bacteria believed to be involved in chronic, adult forms of periodontal infections.     

Activation of human mast cells by retrocyclin and protegrin highlight their immunomodulatory and antimicrobial properties

Preclinical evaluation of Retrocyclins (RC-100, RC-101) and Protegrin-1 (PG-1) antimicrobial peptides (AMPs) is important because of their therapeutic potential against bacterial, fungal and viral infections. Human mast cells (HMCs) play important roles in host defense and wound healing but the abilities of retrocyclins and protegrin-1 to harness these functions have not been investigated. Here, we report that chemically synthesized RC-100 and PG-1 caused calcium mobilization and degranulation in HMCs but these responses were not blocked by an inhibitor of formyl peptide receptor-like 1 (FPRL1), a known receptor for AMPs. However, RC-100 and PG-1 induced degranulation in rat basophilic leukemia (RBL-2H3) cells stably expressing Mas related G protein coupled receptor X2 (MrgX2). Chemical synthesis of these AMPs is prohibitively expensive and post-synthesis modifications (cyclization, disulfide bonds, folding) are inadequate for optimal antimicrobial activity. Indeed, we found that synthetic RC-100, which caused mast cell degranulation via MrgX2, did not display any antimicrobial activity. Green-fluorescent protein (GFP)-tagged RC-101 (analog of RC-100) and GFP-tagged PG-1 purified from transgenic plant chloroplasts killed bacteria and induced mast cell degranulation. Furthermore, GFP-PG1 bound specifically to RBL-2H3 cells expressing MrgX2. These findings suggest that retrocyclins and protegrins activate HMCs independently of FPRL1 but via MrgX2. Harnessing this novel feature of AMPs to activate mast cell''s host defense/wound healing properties in addition to their antimicrobial activities expands their clinical potential. Low cost production of AMPs in plants should facilitate their advancement to the clinic overcoming major hurdles in current production systems.     

抗菌肽protegrin的开发现状与作用机制研究

目的针对抗菌肽protegrin的开发现状、作用机制及研究方法等方面的文献进行了检索及总结,希望有助于同行在现有工作的基础上开发新型的抗菌肽。方法对国内外最新发表的抗菌肽protegrin的相关研究结果进行分析、整理和综合。结果抗菌肽protegrin是目前国际上研究比较深入的抗菌肽之一,而国内还没有相关的开发报道。结论抗菌肽protegrin是一种非常有应用价值和开发前途的新型抗菌物质。