A Chimeric Cationic Peptide Composed of Human β-Defensin 3 and Human β-Defensin 4 Exhibits Improved Antibacterial Activity and Salt Resistance

Abstract

Human beta-defensins (hBDs) play an important role in the host defense against various microbes, showing different levels of antibacterial activity and salt resistance in vitro. It is of interest to investigate whether can chimeric hBD analogs enhanced antibacterial activity and salt resistance. In this study, we designed a chimeric human defensin, named H4, by combining sequences of human beta-defensin-3 (hBD-3) and human beta-defensin-4 (hBD-4), then evaluated its antibacterial activity, salt resistance, and cytotoxic effects. The result showed that the antibacterial activity of H4 against most tested strains, including Klebsiella pneumonia, Enterococcus faecalis, Staphyloccocus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Acinetobacter baumannii was significantly improved compared to that of hBD-3 and hBD-4. Notably, H4 exhibited significantly better antibacterial activity against multidrug resistant isolate A. baumannii MDR-ZJ06 than commonly used antibiotics. Chimeric H4 still showed more than 80% antibacterial activity at high salt concentration (150 μM), which proves its good salt tolerance. The cytotoxic effect assay showed that the toxicity of H4 to Hela, Vero, A549 cells and erythrocytes at a low dose (<10 μg/ml) was similar to that of hBD-3 and hBD-4. In conclusion, given its broad spectrum of antibacterial activity and high salt resistance, chimeric H4 could serve as a promising template for new therapeutic antimicrobial agents.

Structure–activity relationships of antibacterial peptides

“…Moreover, in 2018 Jiang et al demonstrated the importance of the N‐terminal portion of HBDs on its remarkable bactericidal activity (Jiang et al, 2018 ). Lastly, in recent studies Wj and colleagues combined HBD‐3 and HBD‐4 chimerically to further increase their antibacterial activity, proposing them as novel therapeutic antimicrobial agents (Wj et al, 2021 ).…”

Antimicrobial Peptides: From Design to Clinical Application

“…Most AMPs are cationic; therefore, they display low bactericidal activity in high salt conditions due to the competent binding activity of cationic ions with bacterial membrane [97]. A chimeric peptide H4 that is derived from hBD3 and hBD4 exhibited stronger antimicrobial activity against bacteria such as Enterococcus faecalis and S. aureus, with antibacterial activity in high salt conditions [98]. In addition, the N-terminal deletion of three amino acids of hBD3 improved its antimicrobial activity against different bacterial species such as E. coli and Enterococcus faecium, especially in high salt conditions [99].…”

Efficiency of Antimicrobial Peptides Against Multidrug-Resistant Staphylococcal Pathogens

“…Nevertheless, combinations of defensins with methicillin or β-defensins and CAP18 can have a synergistic effect on S. aureus , including MRSA ( Midorikawa et al, 2003 ). H4, a chimeric human defensin that combines the sequences of hBD-3 and hBD-4, showed superior antibacterial activity against S. aureus compared with that of hBD-3 and hBD-4 and conferred high salt tolerance ( Yu et al, 2021 ). hBTD-1 and [D]hBTD-1, chimeric analogues of human β-defensin 1 and θ-defensin, respectively, exhibited considerable activity against S. aureus biofilms as well as planktonic forms ( Mathew et al, 2017 ).…”