Antibacterial Effect of Honey-Derived Exosomes Containing Antimicrobial Peptides Against Oral Streptococci

Abstract

Purpose: Recently, our group found exosome-like extracellular vesicles (EVs) in Apis mellifera honey displaying strong antibacterial effects; however, the underlying mechanism is still not understood. Thus, the aim of this investigation was to characterize the molecular and nanomechanical properties of A. mellifera honey-derived EVs in order to elucidate the mechanisms behind their antibacterial effect, as well as to determine differential antibiofilm properties against relevant oral streptococci. Methods: A. mellifera honey-derived EVs (HEc-EVs) isolated via ultracentrifugation were characterized with Western Blot and ELISA to determine the presence of specific exosomal markers and antibacterial cargo, and atomic force microscopy (AFM) was utilized to explore their ultrastructural and nanomechanical properties via non-destructive immobilization onto poly-L-lysine substrates. Furthermore, the effect of HEc-EVs on growth and biofilm inhibition of S. mutans was explored with microplate assays and compared to S. sanguinis. AFM was utilized to describe ultrastructural and nanomechanical alterations such as cell wall elasticity changes following HEc-EV exposure. Results: Molecular characterization of HEc-EVs identified for the first time important conserved exosome markers such as CD63 and syntenin, and the antibacterial molecules MRJP1, defensin-1 and jellein-3 were found as intravesicular cargo. Nanomechanical characterization revealed that honey-derived EVs were mostly <150nm, with elastic modulus values in the low MPa range, comparable to EVs from other biological sources. Furthermore, incubating oral streptococci with EVs confirmed their antibacterial and antibiofilm capacities, displaying an increased effect on S. mutans compared to S. sanguinis. AFM nanocharacterization showed topographical and nanomechanical alterations consistent with membrane damage on S. mutans. Conclusion: Honey is a promising new source of highly active EVs with exosomal origin, containing a number of antibacterial peptides as cargo molecules. Furthermore, the differential effect of HEC-EVs on S. mutans and S. sanguinis may serve as a novel biofilmmodulating strategy in dental caries.

The Antibacterial and Anti-biofilm Traits of the Novel BMAP-27-Melittin Conjugated Peptide Nanoparticle Against Streptococcus mutans: Clinical Isolates from Oral Cavity

“…A recent study revealed that insect peptides exert antibiofilm effects against major nosocomial pathogens via non-specific mechanisms (37). extracellular vehicles (EVs) from honeybees have exhibited antibiofilm effects against S. mutans and Streptococcus sanguinis (38). Human antimicrobial peptide LL-37 has substantial antibacterial effects (39).…”

Extracellular Vesicles derived from Apis mellifera Royal Jelly promote wound healing by modulating inflammation and cellular responses

“…Furthermore, the peptides Defensin-1 and Jellein-3 were quantified with direct ELISA, as previously described (23). Briefly, one microgram of RJEV protein and negative controls (pre-bleed serum 1:1000, human mesenchymal stem cell protein 30 μg) as well as respective standards were incubated overnight.…”

“…No reuse allowed without permission. Furthermore, the peptides Defensin-1 and Jellein-3 were quantified with direct ELISA, as previously described (23).…”

“…Atomic force microscopy (AFM) characterization RJEV shapes were confirmed using AFM, as previously described (23). Briefly, freshly cleaved mica discs (12mm diameter; Electron Microscopy Sciences, US) were coated with 50µl of 0.1 M solution of poly-L-lysine (PLL, Sigma) for 5 minutes.…”

Antibacterial and Antibiofilm Effect of Honey in the Prevention of Dental Caries: A Recent Perspective

“…Apart from H 2 O 2 and MGO, the recently explored exosome-like extracellular vesicles in honey [ 54 ] display a pronounced antibacterial effect against S. mutans, mediated through nanomechanical alterations resulting in membrane damage [ 55 ]. Detailed molecular characterisation of these honey-derived vesicles has further revealed that MRJP-1, defensin-1 and jellein-3 are cargo proteins in vesicles.…”