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. 2021 Feb 12:12:634323.
doi: 10.3389/fmicb.2021.634323. eCollection 2021.

AOA-2 Derivatives as Outer Membrane Protein A Inhibitors for Treatment of Gram-Negative Bacilli Infections

Rafael Ayerbe-Algaba  1   2 , Nuria Bayó  3 , Ester Verdú  3 , Raquel Parra-Millán  1   2 , Jesús Seco  3 , Meritxell Teixidó  3 , Jerónimo Pachón  2   4 , Ernest Giralt  3   5 , Younes Smani  1   2
Affiliations

AOA-2 Derivatives as Outer Membrane Protein A Inhibitors for Treatment of Gram-Negative Bacilli Infections

Rafael Ayerbe-Algaba et al. Front Microbiol. .

Abstract

Previously, we identified that a cyclic hexapeptide AOA-2 inhibited the interaction of Gram-negative bacilli (GNB) like Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli to host cells thereby preventing the development of infection in vitro and in a murine sepsis peritoneal model. In this work, we aimed to evaluate in vitro a library of AOA-2 derivatives in order to improve the effect of AOA-2 against GNB infections. Ten AOA-2 derivatives were synthetized for the in vitro assays. Their toxicities to human lung epithelial cells (A549 cells) for 24 h were evaluated by determining the A549 cells viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The effect of these peptide derivatives and AOA-2 at 250, 125, 62.5, and 31.25 μg/mL on the attachment of A. baumannii ATCC 17978, P. aeruginosa PAO1 and E. coli ATCC 25922 strains to A549 cells was characterized by adherence and viability assays. None of the 10 derivatives showed toxicity to A549 cells. RW01 and RW06 have reduced more the adherence of ATCC 17978, PAO1 and ATCC 2599 strains to A549 cells when compared with the original compound AOA-2. Moreover, both peptides have increased slightly the viability of infected A549 cells by PAO1 and ATCC 25922 than those observed with AOA-2. Finally, RW01 and RW06 have potentiated the activity of colistin against ATCC 17978 strain in the same level with AOA-2. The optimization program of AOA-2 has generated two derivatives (RW01 and RW06) with best effect against interaction of GNB with host cells, specifically against P. aeruginosa and E. coli.

Keywords: AOA-2 derivatives; Gram-negative bacilli; inhibitor; outer membrane protein A; peptides.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Structure of AOA-2 and its optimized derivatives.
FIGURE 2
FIGURE 2
Bacterial adhesion assay of A. baumannii ATCC 17978, P. aeruginosa PAO1 and E. coli ATCC 25922 in presence of AOA-2 and its derivatives at concentration of 250 μg/mL (A), and 31.25, 62.5, and 125 μg/mL (B). ∗compared to the untreated bacteria, #compared to AOA-2 at 125 or 250 μg/mL, μcompared to AOA-2 at 62.5 μg/mL, †compared to AOA-2 at 31.25 μg/mL, Student’s t-test with P < 0.05.
FIGURE 3
FIGURE 3
Cell viability assay of A. baumannii ATCC 17978, P. aeruginosa PAO1, and E. coli ATCC 25922 at different concentrations of AOA-2 and its derivatives RW01 and RW06. ∗compared to the untreated bacteria, μcompared to AOA-2 at 62.5 μg/mL, †compared to AOA-2 at 31.25 μg/mL, Student’s t-test with P < 0.05.
See this image and copyright information in PMC

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