The Oligo-Acyl Lysyl Antimicrobial Peptide C ₁₂ K-2β ₁₂ Exhibits a Dual Mechanism of Action and Demonstrates Strong In Vivo Efficacy against Helicobacter pylori

Abstract

Helicobacter pylori has developed antimicrobial resistance to virtually all current antibiotics. Thus, there is a pressing need to develop new anti-H. pylori therapies. We recently described a novel oligo-acyl-lysyl (OAK) antimicrobial peptidomimetic, C 12 K-2␤ 12 , that shows potent in vitro bactericidal activity against H. pylori. Herein, we define the mechanism of action and evaluate the in vivo efficacy of C 12 K-2␤ 12 against H. pylori after experimental infection of Mongolian gerbils. We demonstrate using a 1-N-phenylnaphthylamine (fluorescent probe) uptake assay and electron microscopy that C 12 K-2␤ 12 rapidly permeabilizes the bacterial membrane and creates pores that cause bacterial cell lysis. Furthermore, using nucleic acid binding assays, Western blots, and confocal microscopy, we show that C 12 K-2␤ 12 can cross the bacterial membranes into the cytoplasm and tightly bind to bacterial DNA, RNA, and proteins, a property that may result in inhibition of enzymatic activities and macromolecule synthesis. To define the in vivo efficacy of C 12 K-2␤ 12 , H. pylori-infected gerbils were orogastrically treated with increasing doses and concentrations of C 12 K-2␤ 12 1 day or 1 week postinfection. The efficacy of C 12 K-2␤ 12 was strongest in animals that received the largest number of doses at the highest concentration, indicating dose-dependent activity of the peptide (P < 0.001 by analysis of variance [ANOVA]) regardless of the timing of the treatment with C 12 K-2␤ 12 . Overall, our results demonstrate a dual mode of action of C 12 K-2␤ 12 against the H. pylori membrane and cytoplasmic components. Moreover, and consistent with the previously reported in vitro efficacy, C 12 K-2␤ 12 shows significant in vivo efficacy against H. pylori when used as monotherapy. Therefore, OAK peptides may be a valuable resource for therapeutic treatment of H. pylori infection.

Antibacterial activities of almond skins on cagA-positive and-negative clinical isolates of Helicobacter pylori

“…Other flavonoids may also be responsible for the neutralization of the vacA via interference of the toll-like receptor 4 signaling induced by H. pylori [36,37]. A recent study reported that the antimicrobial potential of the oligopeptide C 12 K-2 against H. pylori has a dual mode of action on both membrane and cytoplasmatic components [38]. Although the rate of resistance to clarithromycin has significantly increased in several countries (13), the observed resistance to this antibiotic in the H. pylori isolates tested in the present work was surprisingly low (6%).…”

Synergistic effects of antimicrobial peptide DP7 combined with antibiotics against multidrug-resistant bacteria

“…Strategies to address this problem include the identification of new antibiotics, the application of the principles of microecology, or the development of antimicrobial peptides (AMPs). AMPs are one of the most promising antibacterial drugs that can be substituted for antibiotics because they have advantages such as high antimicrobial efficacy1–3 and broad-spectrum activity 1,4. Another way to resolve the problem of multidrug-resistant bacteria is by combining different drugs.…”

Antibiotic treatment forHelicobacter pylori: Is the end coming?

“…Human beta defensin 2 and 3 are differentially expressed in gastric mucosa during H. pylori infection [154] . Oligo-acyl-lysyl (OAK) peptides, which have a structure and function similar to those of natural AMPs, have broad-spectrum antibacterial activity and anti-H. pylori effect in vivo [155] . Unlike the natural AMPs, OAK peptides are without known proteolytic cleavage sites and thus, resistant to enzymatic cleavage.…”