Effect Of Antimicrobial Peptides On The Growth Of Oral Pathogens And Streptococcus Mutans Biofilm And Anti-inflammatory Activity

Dental caries and periodontitis are common oral bacterial infectious diseases. Theirprevention and treatment requires control of the causative pathogens, such as Streptococcusmutans, that exist within dental plaque. As one of the attractive future substitutes forconventional antibiotics, antimicrobial peptides (AMPs), both natural and synthetic, havebeen widely tested and used for controlling bacterial infections.. The most of theantimicrobial peptides with positive charge have strong electrostatic attraction to thenegatively charged membrane of bacteria, resulting in the binding of AMPs to the anioniclipids of biomembranes and the formation of pores involving the barrel-stave model or by theinduction of phospholipid “flip-flop” based on the carpet or toroidal model. It is difficult forbacteria to develop resistance to antimicrobial peptides. Besides, MPs have antimicrobialactivity against ungi.In this paper,the efficacy of antimicrobial peptides, collected in theantimicrobial peptide library constructed by our laboratory, in killing several major cariogenicand periodontics’ pathogenic bacteria as well as Candida albicans was tested in vitro. Theresults showed that antimicrobial peptides L-K6、L-K6V2�'�Temporin-1CEa exhibited highantimicrobial activity, Lactobacillus acidophilus and Streptococcus mutans were the mostsusceptible strains compared with other species tested., MIC values were less than10μM. Theantimicrobial peptide Chensinin-1B, L-K6and Temporin-1CEa exhibited high antimicrobialactivity against the Streptococcus mutans and Candida albicans. The bactericidal kinetics ofL-K6、L-K6V2and temporin-1CEa was studied using Time-Kill curve, post-antibiotic effect(PAE) experiment.LIVE/DEAD bacterial activity studied by means of antimicrobial peptidescariogenic bacteria and the role of candidiasis pathogens. Streptococcus mutans, the causativeagent of dental caries, was chosen for in-depth testing. The effect of peptides on biofilmformation and on pre-formed biofilm was also examined. For biofilm studies, confocal laserscanning microscopy was used to observe and analyze bacterial biofilm. The results showedthat L-K6also inhibited S. mutans biofilm formation (MBIC50:6.25μM), and reduced1-day-old developed S. mutans biofilm (MBRC50:12.5μM). CLSM images showed that peptide significantly reduced the viability of biofilm cells. This study suggests thatpeptide may have a potential clinical application in treating dental caries by killing S. mutanswithin dental plaque. Furthermore, L-K6, chensinin-1b and temporin-1CEa were sufficient toinhibit LPS, LTA or interleukin-1β-induced secretion of interleukin-8and TNF-α in THP-1cells, suggesting that L-K6, chensinin-1b and temporin-1CEa can act both as an anti-biofilmagent in an anaerobic environment and as an anti-inflammatory agent in infected tissues.