Effects of human β-defensin 3 fused with carbohydrate-binding domain on the function of type III secretion system in Pseudomonas aeruginosa PA14

Abstract

Antimicrobial peptides are considered to be one of the candidate antimicrobial agents for antibiotic-resistant bacterial infection in the future. The effects of antimicrobial peptide hBD3-CBD on Pseudomonas aeruginosa PA14 and PA14 ΔexsA were analyzed by the bactericidal effects, hemolysis assays, pyocyanin pigment productions, and virulence factor expressions (exoU, exoS, hcnA, and lasB). Pyocyanin production and virulence factor expressions are important features of the type III secretion system in Pseudomonas aeruginosa. HBD3-CBD killed PA14 and PA14 ΔexsA with similar efficiency; it lowered the hemolysis levels of PA14 and PA14 ΔexsA and reduced the pyocyanin production, biofilm formation, and exoU, exoS, and lasB expressions in PA14. Compared with PA14, PA14 ΔexsA showed a lower hemolysis effect, pyocyanin production, exoU, and lasB expressions. The effects of hBD3-CBD on the PA14 toxin secretion were similar to the changes in the type III secretion system mutant isolate PA14 ΔexsA. Our results demonstrated that the type III secretion system was involved in the biological functions on PA 14 from hBD3-CBD. Keywords Antimicrobial peptide. hBD3. Pseudomonas aeruginosa. T3SS Antimicrobial peptides (AMPs) are polypeptides with broadspectrum antimicrobial activity against bacteria, fungi, and other microorganisms [1]. Their potent activity at low concentrations against many pathogenic organisms, including multiresistant strains, makes AMPs attractive candidates as antimicrobial agents to many inflammatory and infectious diseases [2]. Human beta-defensin-3 (hBD3) is a multifunctional peptide and widely expressed in oral and other tissues. The antiinfective effects of this polypeptide have been confirmed by several studies [3-5].

Pseudomonas aeruginosa reference strains PAO1 and PA14: A genomic, phenotypic, and therapeutic review

“…Also, PAO1 and PA14 have been used to test novel QSIs, which ideally would prevent P. aeruginosa from forming difficult-to-treat biofilms and can be used in conjunction with traditional antibiotics. Methods to restore antibiotics sensitively are ideal, but novel therapeutics, such as AMPs, are also critical in expanding the arsenal of therapeutics against P. aeruginosa, as they are less likely to provoke resistance (Mulani et al, 2019) experiments with PAO1 and PA14 have led to the identification of potential novel therapeutics that have demonstrated success in killing P. aeruginosa and reducing virulence in areas such as QS, secretion, and motility (Beaudoin et al, 2018;Mulani et al, 2019;Ben Jeddou et al, 2020;Wu et al, 2020;Wilkinson et al, 2021). However, it is important to note that the testing environment can be as important as the therapeutic itself.…”

“…These results show the potential for peptide 1080 to impact the early stages of P. aeruginosa infection. Human β-defensin 3 combined with a carbohydrate-binding domain was efficacious against PA14 in vitro, reduced biofilm formation, and production of factors of T3SS, including pyocyanin, exoU, exoS, and lasB ( Wu et al, 2020 ). Another synthetic AMP-dendrimer G3KL, reportedly killed PA14 faster than polymyxin B without producing resistant mutants ( Ben Jeddou et al, 2020 ).…”

“…Many AMPs have demonstrated activity against P. aeruginosa , but hurdles to clinical application remain. Protease degradation, possible mammalian cytotoxicity, deleterious local or systemic effects, production expense, gut flora changes, and loss of potency in decreased salt concentrations or with plasma proteins are among the in vivo challenges of AMPs ( Mulani et al, 2019 ; Wu et al, 2020 ). Research that underscores AMP structural modifications, encapsulation or other delivery methods, and synergistic antibiotic applications is a key to overcoming these challenges ( Mulani et al, 2019 ).…”