title: The oligo-acyl lysyl antimicrobial peptide C₁₂K-2β₁₂ 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-2β(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-2β(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-2β(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-2β(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-2β(12), H. pylori-infected gerbils were orogastrically treated with increasing doses and concentrations of C(12)K-2β(12) 1 day or 1 week postinfection. The efficacy of C(12)K-2β(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-2β(12). Overall, our results demonstrate a dual mode of action of C(12)K-2β(12) against the H. pylori membrane and cytoplasmic components. Moreover, and consistent with the previously reported in vitro efficacy, C(12)K-2β(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.
authors: Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
authors: Morris O
authors: MO
authors: Makobongo
authors: Hanan
authors: H
authors: Gancz
authors: Beth M
authors: BM
authors: Carpenter
authors: Dennis P
authors: DP
authors: McDaniel
authors: D Scott
authors: DS
authors: Merrell
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives; D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000378:metabolism; D015153:Blotting, Western; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004269:DNA, Bacterial / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D024901:Drug Resistance, Multiple, Bacterial; D005456:Fluorescent Dyes; D005849:Gerbillinae; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D057786:Peptidomimetics / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000378:metabolism; D011485:Protein Binding; D012329:RNA, Bacterial / Q000378:metabolism; D013270:Stomach / Q000187:drug effects / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D004269:DNA, Bacterial; D005456:Fluorescent Dyes; D057786:Peptidomimetics; D012329:RNA, Bacterial; C005444:N-phenyl-1-naphthylamine; D015057:1-Naphthylamine