Biofilms lead to approximately 65% of infections, and these infections are hard to treat. Thus, it is crucial to identify effective antibiofilm agents with low cytotoxicity. Peptides with antibiofilm ...activity have been regarded as promising solutions, and peptides with MBICs (minimal biofilm inhibitory concentrations) that are lower than their minimal inhibitory concentration (MICs) (minimal inhibitory concentrations) are appealing. Therefore, we systematically summarized and classified previously reported peptides with antibiofilm activity. A total of 51 peptides with antibiofilm activity were classified into 14 categories. The MICs and MBICs of these fourteen representative peptides, one selected from each category, were compared against the Gram-positive bacterium
Streptococcus mutans
, the Gram-negative bacterium
Pseudomonas aeruginosa
, and the fungus
Candida albicans
. Six representative peptides (C5-pleurocidin, C6-Pac-525, C9-protegrin-1, C11-TetraF2W-RR, C13-WLBU2, and C14-melittin) showed antibiofilm activity against both bacteria and fungi, and among these 6 representative peptides, 4 peptides (C9-protegrin-1, C11-TetraF2W-RR, C13-WLBU2, and C14-melittin) could prevent biofilm formation with lower MBIC values than their MICs. CLSM (confocal laser scanning microscopy), SEM (scanning electron microscopy), and TEM (transmission electron microscopy) were further used to observe the morphologies of the biofilms after treatment with the peptides. Among the above 4 peptides, WLBU2 and melittin sparsely scattered the biofilms without destroying the bacteria. In conclusion, the currently reported peptides with antibiofilm activity are limited in number, but peptides with lower MBICs than MICs exist as promising candidates against biofilm-related infections and need further study.
Key points
•
Antibiofilm peptides could inhibit biofilm formation with MBICs that are lower than MICs.
•
The mechanism of antibiofilm peptides is not only due to antimicrobial activity.
Dental follicle (DF) can develop into periodontal tissues including periodontal ligament, cementum, and alveolar bone. Possessing superior pluripotency and osteogenic capacity, dental follicle stem ...cells (DFSCs) have become a promising stem cell source for bone regeneration and periodontal engineering. However, the mechanisms underlying DFSCs‐mediated osteogenesis remain elusive. Our previous long noncoding RNA (lncRNA) microarray revealed that lncRNA HOTAIRM1 was significantly higher expressed in human DFSCs (hDFSCs) compared with human periodontal ligament stem cells (hPDLSCs). lncRNA HOTAIRM1, an antisense transcript of the HOXA1/2 intergenic region, can epigenetically regulate proximal and distant HOXA genes through histone and DNA methylation. HOXA2, a target of HOTAIRM1, is crucial for cranial neural crest morphogenesis, branchial arches development, and osteogenesis. However, the roles of both HOTAIRM1 and HOXA2 in odontogenic stem cells remain unknown. Here, we investigated the functions and regulatory mechanisms of these two genes in hDFSCs. Both genes were confirmed highly expressed in hDFSCs compared with hPDLSCs, and they displayed similar expression patterns in the DF and surrounding periodontium during mice tooth morphogenesis. Knockdown of either HOTAIRM1 or HOXA2 inhibited osteogenic differentiation of hDFSCs, while overexpressed HOTAIRM1 inhibited hDFSCs proliferation and promoted osteogenesis. Furthermore, HOTAIRM1 inhibited both overall DNMT1 expression and DNMT1 enrichment on HOXA2 promoter, mechanically binding to the CpG islands of the HOXA2 promoter region, leading to hypomethylation and HOXA2 induction. These findings suggested that HOTAIRM1 promoted the osteogenesis of hDFSCs by epigenetically regulating HOXA2 via DNMT1. Taken together, HOTARIM1 and HOXA2 exerted pivotal functions in hDFSCs, and the regulatory mechanism of HOTARIM1 within the HOXA cluster was uncovered.
Dental follicle stem cells (DFSCs) have become a promising stem cell source for bone regeneration and periodontal engineering, however, the mechanisms underlying DFSCs‐mediated osteogenesis remain elusive. Here we demonstrated that HOTAIRM1 and HOXA2 were highly expressed in human DFSCs (hDFSCs), and HOTAIRM1 could promote the osteogenesis of hDFSCs by epigenetically regulating HOXA2 via DNMT1.
The aim of this meta‐analysis is to evaluate myeloblastosis (MYB) as a prognostic marker for patients with adenoid cystic carcinoma (ACC) with respect to MYB gene fusion, MYB protein expression, and ...tumor sites.
We comprehensively searched PubMed, Embase, Web of Science, and Cochrane libraries. Ten studies concerning the prognostic comparisons between MYB positivity and negativity were included.
The combined positive rates of MYB gene fusion and protein expression were 57.2% and 62.3%, respectively. Overall, no significant prognostic differences were observed between MYB‐positive and MYB‐negative ACCs. When further divided into MYB gene fusion and MYB protein expression subgroups, no significant differences were observed for any survival outcome (overall survival, disease‐free survival, and local control rate). Moreover, MYB also demonstrated no prognostic value in head and neck ACCs.
In conclusion, the current studies reveal that MYB is not a good prognostic marker for ACC.
Bacterial membrane vesicles (MVs) are used as a tool for intercellular communication and seem essential for bacterial survival. However, few data are available on MVs generated by
Streptococcus ...mutans
, which is the main aetiological agent of dental caries. The present study presents an integrated proteomics and metabolomics analysis of MVs isolated from
S. mutans
at initial pH values of 7.5 and 5.5 and explores their function. The results showed that
S. mutans
releases more MVs with smaller diameters under acidic conditions than under neutral conditions. Proteomic analysis showed 344 common vesicular proteins, including various virulence factors. The expressions of 140 individual proteins and 37 metabolites were altered as a result of culturing
S. mutans
at different pH values. Co-analyses of proteomic and metabolomics data indicated that ABC transporters underwent significant changes under acid pressure. We concluded that
S. mutans
produced MVs at different pH values to carry proteins associated with cariogenesis. Moreover, the alterations of
S. mutans
MVs under acid pressure were associated with ABC transporters. These results increase our knowledge of
S. mutans
MVs and imply that
S. mutans
MVs may play a functional role in carious infection.
Key points
•
S. mutans MVs contained virulence factor-related proteins, even at low pH values.
•
Integrated proteomics and metabolomics analysis showed that S. mutans MVs alterations under acidic conditions were associated with ABC transporters.
Introduction: Type 2 diabetes mellitus (T2DM) is commonly accompanied by obesity and non-alcoholic fatty liver disease (NAFLD), yet the mechanism underlying diabetes-related NAFLD is not fully ...understood. It has been reported that melatonin can regulate glucose and lipid metabolism. This study aims to investigate the actions and mechanisms of melatonin toward the development of diabetes-related NAFLD. Methods: Melatonin (bid, 30 mg/kg/day, i.p.) was administrated to db/db mice for 8 weeks, while saline was administrated to db/m mice. The metabolic parameters of mice were measured using an automatic biochemistry analyzer. The oxidative stress indexes and mitochondrial membrane potential (MMP) were determined with kits. Pathological assessment in liver tissues was used to analyze the effects of melatonin on hepatic steatosis. The levels of IL-1β and IL-18 were detected with ELISA kits. The mRNA levels of NLRP3 inflammasome were detected using quantitative real-time PCR assay, and protein expressions were estimated using Western blotting assay. Immunofluorescence staining was used to evaluate the caspase-1 expression in the liver. Results: Melatonin treatment significantly reduced blood glucose, serum insulin, body weight, related liver weight, serum lipids, and hepatic enzymes in db/db mice. Melatonin markedly corrected the NAFLD phenotypes, including lipid accumulation, steatohepatitis, fibrosis, and oxidative stress levels. Melatonin significantly improved the MMP level and decreased the serum IL-1β and IL-18 concentrations. The mRNA levels of the NLRP3 inflammasome could also be remarkably reversed by melatonin in the liver tissues. The activation of the NLRP3 inflammasome was also suppressed, evidenced by the downregulated proteins of NLRP3, caspase-1, IL-1β, and IL-18. The enhanced fluorescence intensity of caspase-1 in the liver tissues was also obviously weakened by the melatonin treatment. Conclusion: Our study concluded that melatonin could safeguard against NAFLD by improving hepatic steatosis in db/db mice, and this action could be associated with the regulation of the NLRP3 inflammasome activation.
Infiltration and sealing are micro-invasive treatments for arresting proximal non-cavitated caries lesions; however, their efficacies under different conditions remain unknown. This systematic review ...and meta-analysis aimed to evaluate the caries-arresting effectiveness of infiltration and sealing and to further analyse their efficacies across different dentition types and caries risk levels.
Six electronic databases were searched for published literature, and references were manually searched. Split-mouth randomised controlled trials (RCTs) to compare the effectiveness between infiltration/sealing and non-invasive treatments in proximal lesions were included. The primary outcome was obtained from radiographical readings.
In total, 1033 citations were identified, and 17 RCTs (22 articles) were included. Infiltration and sealing reduced the odds of lesion progression (infiltration vs. non-invasive: OR = 0.21, 95% CI 0.15-0.30; sealing vs. placebo: OR = 0.27, 95% CI 0.18-0.42). For both the primary and permanent dentitions, infiltration and sealing were more effective than non-invasive treatments (primary dentition: OR = 0.30, 95% CI 0.20-0.45; permanent dentition: OR = 0.20, 95% CI 0.14-0.28). The overall effects of infiltration and sealing were significantly different from the control effects based on different caries risk levels (OR = 0.20, 95% CI 0.14-0.28). Except for caries risk at moderate levels (moderate risk: OR = 0.32, 95% CI 0.01-8.27), there were significant differences between micro-invasive and non-invasive treatments (low risk: OR = 0.24, 95% CI 0.08-0.72; low to moderate risk: OR = 0.38, 95% CI 0.18-0.81; moderate to high risk: OR = 0.17, 95% CI 0.10-0.29; and high risk: OR = 0.14, 95% CI 0.07-0.28). Except for caries risk at moderate levels (moderate risk: OR = 0.32, 95% CI 0.01-8.27), infiltration was superior (low risk: OR = 0.24, 95% CI 0.08-0.72; low to moderate risk: OR = 0.38, 95% CI 0.18-0.81; moderate to high risk: OR = 0.20, 95% CI 0.10-0.39; and high risk: OR = 0.14, 95% CI 0.05-0.37).
Infiltration and sealing were more efficacious than non-invasive treatments for halting non-cavitated proximal lesions.
Amyloid fibrils are important scaffold in bacterial biofilms.
Streptococcus mutans
is an established cariogenic bacteria dwelling within biofilms, and C123 segment of P1 protein is known to form ...amyloid fibrils in
S. mutans
biofilms, among which C3 segment could serve as a promising anti-amyloid target due to its critical role in C123-P1 interactions. Recently, small molecules have been found to successfully inhibit biofilms by targeting amyloid fibrils. Thus, our study aimed to screen small molecules targeting C3 segment with the capacity to influence amyloid fibrils and
S. mutans
biofilms. In silico screening was utilized to discover promising small molecules, which were evaluated for their effects on bacterial cells and amyloid fibrils. We selected 99 small molecules and enrolled 55 small molecules named D1–D55 for crystal violet staining. Notably, D25 selectively inhibit
S. mutans
biofilms but had no significant influence on biofilms formed by
Streptococcus gordonii
and
Streptococcus sanguinis
, and D25 showed no bactericidal effects and low cytotoxicity. In addition, amyloid fibrils in free-floating bacteria, biofilms and purified C123 were quantified with ThT assays, and the differences were not statistically significant in the presence or absence of D25. Morphological changes of amyloid fibrils were visualized with TEM images, where amorphous aggregates were obvious coupled with long and atypical amyloid fibrils. Moreover, amyloid-related genes were upregulated in response to D25. In conclusion, D25 is a promising antimicrobial agent with the capacity to influence amyloid fibrils and inhibit
S. mutans
biofilms.
AFhPs aggregated into rigid amyloid fibers, which agglutinated microbes and exerted as antibiofilm agents. AFhPs have no microbicidal activity and little or no cytotoxicity. AFhPs may be utilized as ...novel antibiofilm agents.
Summary
Evidence suggests that short amyloid‐forming peptides derived from bacterial proteomes have functional roles; however, the reported activities are diverse and the underlying mechanisms remain unclear. In this study, we simulated short amyloid‐forming peptides from the amyloid‐forming truncated protein C123 of Streptococcus mutans (S. mutans), studied their biological functions in microbial proliferation and biofilm formation, and further investigated the underlying mechanism. Fourteen hexapeptides were simulated, 13 of which were successfully synthesized. We found that the amyloid‐forming hexapeptides (AFhPs) displayed efficient broad‐spectrum antibiofilm activity against the Gram‐positive bacteria S. mutans, Streptococcus sanguis and Staphylococcus aureus, Gram‐negative bacteria Escherichia coli and fungus Candida albicans, by aggregating into rigid amyloid fibres agglutinating microbes, whereas the non‐amyloid‐forming hexapeptides (non‐AFhPs) did not. The AFhPs did not kill microbes and showed little or no cytotoxicity. Furthermore, a set of AFhPs displayed broad‐spectrum antibiofilm activity, regardless of its source. The microbial cell wall carbohydrates, peptidoglycan (PGN), lipoteichoic acid (LTA), glucan and zymosan A, mediated AFhP binding and triggered significant AFhP fibrillation. Although amyloid fibres agglutinated lipid membrane model – large unilamellar vesicles (LUVs) – and LUVs facilitated AFhP fibrillation, the roles of lipid membranes in AFhP antibiofilm activities remain to be elucidated. We highlight the potential use of AFhPs as novel antibiofilm agents.
Evidence suggests that small noncoding RNAs (sRNAs) are involved in the complex regulatory networks governing biofilm formation. Few studies have investigated the role of sRNAs in Streptococcus ...mutans (S. mutans). In the present study, the association between sRNA and biofilm formation in S. mutans was explored. sRNAs that are differentially expressed in the biofilm and planktonic states of this bacterium were identified by quantitative real‐time PCR (qRT‐PCR). Confocal laser scanning microscopy was used to investigate the characteristics of biofilm formation in a standard strain of S. mutans (UA159, ATCC 700610) and ten clinical strains. Bioinformatics analyses were employed to predict and examine potential sRNA regulatory pathways. The results showed that sRNA0426 has a strong positive relationship with dynamic biofilm formation. Moreover, sRNA0426 expression was positively correlated with exopolysaccharide (EPS) production. Bioinformatics analyses showed that sRNA0426 is involved in biofilm formation such as metabolic pathways, especially carbon metabolism. Five target mRNAs (GtfB, GtfC, GtfD, ComE, and CcpA) involved in the synthesis of EPS were selected for further evaluation; the expression levels of three of these mRNAs (GtfB, GtfC, and CcpA) were positively correlated with sRNA0426 expression levels, and the expression level of one (ComE) was negatively correlated. In conclusion, the results suggested that sRNA0426 may play an important and positive role in the biofilm formation of S. mutans and provide novel insight into the S. mutans biofilm regulatory network.
This study focuses on the role of small noncoding RNA both in standard Streptococcus mutans and clinical strain biofilms. sRNA0426 is potentially involved in the biofilm formation of S. mutans. The results of this study provide new insights into the complex biofilm regulatory network in S. mutans, which infers a new possibility for dental caries prevention.
There are signs that amyloid fibers exist in
Streptococcus mutans
biofilm recently. However, the characteristics of amyloid fibers and fibrillation influencing factors are unknown. In this study, we ...firstly used transmission electron microscopy (TEM) and atomic force microscopy (AFM) to observe the morphology of amyloid fibers in
S. mutans
. Then the extracted amyloid fibers from biofilm were studied for their characteristics. Further, the influencing factors, PH, temperature and eDNA, were investigated. Results showed there were mainly two morphologies of amyloid fibers in
S. mutans
, different in width. Amyloid fibers inhibitor-EGCG obviously destroyed biofilm at different stages, which is dose-dependent. The amount of amyloid fibers positively correlated with biofilm biomass in clinical isolates. Acidic pH and high temperature obviously accelerated amyloid fibrillation. During amyloid fibrillation, amyloid growth morphologies were observed by TEM and results showed two growth morphologies. Amyloid fibers formed complex with eDNA, which we call (a)eDNA. The molecular weight of (a)eDNA was similar to genomic DNA, greatly larger than that of eDNA in matrix. Combined use of DNase I and EGCG was more efficiently in inhibiting amyloid fibers and biofilm biomass. In conclusion, amyloid fibers are the crucial structures for
S. mutans
biofilm formation, showing two types of morphology. Acidic pH and temperature can obviously accelerate amyloid fibrillation. Amyloid fibers form complex with (a)eDNA and combined use of DNase and amyloid fiber inhibitor is more efficiently in inhibiting
S. mutans
biofilm formation.
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