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New insights into the antimicrobial effect of mast cells against Enterococcus faecalis.

ABSTRACT: Enterococcus faecalis has emerged as an important cause of life-threatening multidrug-resistant bacterial infections in the hospital setting. The pathogenesis of enterococcal infections has remained a relatively neglected field despite their obvious clinical relevance. The objective of this study was to characterize the interactions between mast cells (MCs), an innate immune cell population abundant in the intestinal lamina propria, and E. faecalis. This study was conducted with primary bone marrow-derived murine MCs. The results demonstrated that MCs exerted an antimicrobial effect against E. faecalis that was mediated both by degranulation, with the concomitant discharge of the antimicrobial effectors contained in the granules, and by the release of extracellular traps, in which E. faecalis was snared and killed. In particular, the cathelicidin LL-37 released by the MCs had potent antimicrobial effect against E. faecalis. We also investigated the specific receptors involved in the recognition of E. faecalis by MCs. We found that Toll-like receptors (TLRs) are critically involved in the MC recognition of E. faecalis, since MCs deficient in the expression of MyD88, an adaptor molecule required for signaling by most TLRs, were significantly impaired in their capacity to degranulate, to reduce E. faecalis growth as well as to release tumor necrosis factor alpha (TNF-?) and interleukin 6 (IL-6) after encountering this pathogen. Furthermore, TLR2 was identified as the most prominent TLR involved in the recognition of E. faecalis by MCs. The results of this study indicate that MCs may be important contributors to the host innate immune defenses against E. faecalis.

SUBMITTER: Scheb-Wetzel M

PROVIDER: S-EPMC4249337 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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New insights into the antimicrobial effect of mast cells against Enterococcus faecalis.

Scheb-Wetzel Matthias M Rohde Manfred M Bravo Alicia A Goldmann Oliver O

Infection and immunity 20140811 11

Enterococcus faecalis has emerged as an important cause of life-threatening multidrug-resistant bacterial infections in the hospital setting. The pathogenesis of enterococcal infections has remained a relatively neglected field despite their obvious clinical relevance. The objective of this study was to characterize the interactions between mast cells (MCs), an innate immune cell population abundant in the intestinal lamina propria, and E. faecalis. This study was conducted with primary bone mar ...[more]

PMID: 25114115

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Project description:To determine the antibacterial effect of propolis nanoparticles (PNs) as an endodontic irrigant against Enterococcus faecalis biofilm inside the endodontic root canal system. Two-hundred-ten extracted human teeth were sectioned to obtain 6 mm of the middle third of the root. The root canal was enlarged to an internal diameter of 0.9 mm. The specimens were inoculated with E. faecalis for 21 days. Following this, specimens were randomly divided into seven groups, with 30 dentinal blocks in each group including: group I-saline; group II-propolis 100 µg/mL; group III-propolis 300 µg/mL; group IV-propolis nanoparticle 100 µg/mL; group V-propolis nanoparticle 300µg/mL; group VI-6% sodium hypochlorite; group VII-2% chlorhexidine. Dentin shavings were collected at 200 and 400 ?m depths, and total numbers of CFUs were determined at the end of one, five, and ten minutes. The non-parametric Kruskal-Wallis and Mann-Whitney tests were used to compare the differences in reduction in CFUs between all groups, and probability values of p < 0.05 were set as the reference for statistically significant results. The antibacterial effect of PNs as an endodontic irrigant was also assessed against E. faecalis isolates from patients with failed root canal treatment. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were also performed after exposure to PNs. A Raman spectroscope, equipped with a Leica microscope and lenses with curve-fitting Raman software, was used for analysis. The molecular interactions between bioactive compounds of propolis (Pinocembrin, Kaempferol, and Quercetin) and the proteins Sortase A and ?-galactosidase were also understood by computational molecular docking studies. PN300 was significantly more effective in reducing CFUs compared to all other groups (p < 0.05) except 6% NaOCl and 2% CHX (p > 0.05) at all time intervals and both depths. At five minutes, 6% NaOCl and 2% CHX were the most effective in reducing CFUs (p < 0.05). However, no significant difference was found between PN300, 6% NaOCl, and 2% CHX at 10 min (p > 0.05). SEM images also showed the maximum reduction in E. faecalis with PN300, 6% NaOCl, and 2% CHX at five and ten minutes. CLSM images showed the number of dead cells in dentin were highest with PN300 compared to PN100 and saline. There was a reduction in the 484 cm-1 band and an increase in the 870 cm-1 band in the PN300 group. The detailed observations of the docking poses of bioactive compounds and their interactions with key residues of the binding site in all the three docking protocols revealed that the interactions were consistent with reasonable docking and IFD docking scores. PN300 was equally as effective as 6% NaOCl and 2% CHX in reducing the E. faecalis biofilms.

Dataset Information

New insights into the antimicrobial effect of mast cells against Enterococcus faecalis.

Publications

New insights into the antimicrobial effect of mast cells against Enterococcus faecalis.

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