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Synergy Between Proline-Rich Antimicrobial Peptides and Small Molecule Antibiotics Against Selected Gram-Negative Pathogens in vitro and in vivo.

ABSTRACT: As monotherapy, modified proline-rich antimicrobial peptides (PrAMPs) protect animals from experimental bacteremia in a dose-dependent manner. We evaluated the in vitro synergy of a modified PrAMP, A3-APO, a dimer, previously shown to inhibit the 70 kDa bacterial heat shock protein DnaK, with imipenem or colistin against two antibiotic-resistant pathogens; a carbapenemase-expressing Klebsiella pneumoniae strain K97/09 and Acinetobacter baumannii (ATCC BAA-1605). Combining antimicrobials resulted in synergy for PrAMP/colistin combination against both K. pneumoniae and A. baumannii (?FIC = 0.08 both) and additive activity for the A3-APO/imipenem combination against K. pneumoniae (?FIC = 0.53). Chex1-Arg20, (designated as ARV-1502 in preclinical development), the single chain PrAMP monomer of A3-APO, showed synergy with meropenem against a carbapenem-resistant uropathogenic Escherichia coli strain (?FIC = 0.38). In a murine bacteremia model using K97/09, A3-APO at 1 mg/kg demonstrated improved survival when co-administered with standard (10 mg/kg) or subtherapeutic (1 mg/kg) doses of colistin at 36 h (p < 0.05). Surprisingly, the survival benefit of A3-APO was augmented when the A3-APO dose was decreased by 50% to 0.5 mg/kg (p < 0.02) in conjunction with a subtherapeutic colistin dose (1 mg/kg). ARV-1502, as monotherapy demonstrated prolonged (>24 h) activity in a mouse Escherichia coli infection assay. Co-treatment with ARV-1502 and subtherapeutic doses of ceftazidime (150 mg/kg) was studied in a mouse model of melioidosis. ARV-1502 provided a 50% improvement in long-term (62 days) survival, but only at the lowest of 3 administered doses; survival advantage was demonstrated at 2.5 mg/kg but not at 5 or 10 mg/kg. The mortality benefit of combination therapies was not routinely accompanied by a parallel decline in blood or tissue bacterial counts in surviving animals, suggesting that the anti-infective activity of the host defense peptides (HDP) is broader than simply bacterial eradication. In fact, the hormetic effect observed in either animal models suggest that low dose HDP treatment may change the dominant mode of action in experimental bacteremia.

SUBMITTER: Otvos L

PROVIDER: S-EPMC6102830 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Synergy Between Proline-Rich Antimicrobial Peptides and Small Molecule Antibiotics Against Selected Gram-Negative Pathogens in vitro and in vivo.

Otvos Laszlo L Ostorhazi Eszter E Szabo Dora D Zumbrun Steven D SD Miller Lynda L LL Halasohoris Stephanie A SA Desai Puvi D PD Int Veldt Sharon M SM Kraus Carl N CN

Frontiers in chemistry 20180814

As monotherapy, modified proline-rich antimicrobial peptides (PrAMPs) protect animals from experimental bacteremia in a dose-dependent manner. We evaluated the in vitro synergy of a modified PrAMP, A3-APO, a dimer, previously shown to inhibit the 70 kDa bacterial heat shock protein DnaK, with imipenem or colistin against two antibiotic-resistant pathogens; a carbapenemase-expressing Klebsiella pneumoniae strain K97/09 and Acinetobacter baumannii (ATCC BAA-1605). Combining an ...[more]

PMID: 30155456

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Project description:Proline-rich antimicrobial peptides (PrAMPs) kill bacteria via a nonlytic mechanism in which they permeate through the outer membrane, utilize protein-mediated transport across the inner membrane, and target the ribosome to inhibit protein synthesis. We previously reported that substitutions of oncocin ( VDKPPYLPRPRPPRRIYNR-NH2 ) with a pair of cationic residues improved the antimicrobial activity. In this study, we applied the design protocol to three other PrAMPs: apidaecin-1b, pyrrhocoricin, and bactenecin 7(1-16) and found that the substitutions (R4K and I8K/R) for apidaecin-1b improve the activity by twofold (p?<?.05) against nonpathogenic Escherichia coli. Moreover, the substitutions (L7K/R and R14K) for pyrrhocoricin improve the activity by 2-10-fold (p?<?.05) against some strains of E. coli and Salmonella Typhimurium. We also performed activity tests against inner membrane protein (SbmA or YgdD) knockout strains. The result is consistent with previous studies that SbmA is the major transporter for apidaecin-1b and pyrrhocoricin derivatives. However, bactenecin 7(1-16) functions independently of these transporters. In addition, several apidaecin-1b derivatives exhibit enhanced activity relative to wild-type only in the absence of SbmA, which is consistent with mutations that enhance transport across the inner membrane. A high performance liquid chromatography-based kinetic assay for cellular association and internalization demonstrates that the selected cationic mutations can improve cellular association in minimal media, but this enhanced association is not required for increased activity, which suggests the importance of inner membrane transport. These functional studies on cationic mutants of PrAMPs advance understanding of potency and mechanism and advance the ability to engineer improved antimicrobials as evidenced by the identification of the pyrrhocoricin mutant (L7R and R14K) with 10-fold elevated potency against pathogenic E. coli.

Dataset Information

Synergy Between Proline-Rich Antimicrobial Peptides and Small Molecule Antibiotics Against Selected Gram-Negative Pathogens in vitro and in vivo.

Publications

Synergy Between Proline-Rich Antimicrobial Peptides and Small Molecule Antibiotics Against Selected Gram-Negative Pathogens <i>in vitro</i> and <i>in vivo</i>.

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