Inhibitory effects of sodium new houttuyfonate on growth and biofilm formation of Streptococcus mutans

Natural TPs inhibit biofilm formation by Multidrug-resistant Acinetobacter baumannii and biofilm-induced pulmonary inflammation

Multidrug-resistant Acinetobacter baumannii (MDRAB) infections cause elevated rates of patient deaths in intensive care units owing to the high antibiotic resistance of the clinical isolates. The advent of multidrug-resistant A. baumannii (MDRAB) strains and the formation of their biofilms are cause for concern. Tea polyphenols (TPs), which exhibit antimicrobial activity, is an ideal alternative strategy for lowering the incidence of nosocomial bacterial infections. This study was conducted to determine the effects of TPs on MDRAB. The antimicrobial and anti-biofilm activities of TPs against MDRAB were investigated in vitro using the propidium iodide assay, scanning electron microscopy, transmission electron microscopy, crystalline violet staining and real-time quantitative PCR (qPCR). The in vivo anti-biofilm and anti-inflammatory effects of TPs were studied using a rat model of MDRAB biofilm-induced pulmonary inflammation. TPs effectively inhibited the proliferation of MDRAB and damaged its cell membrane. Additionally, they inhibited MDRAB biofilm formation by reducing the content of microbial extracellular polymeric substances and altering the expression of genes related to biofilm formation. Moreover, TPs reduced pathological features of lung injury and alleviated MDRAB biofilm-induced pneumonia in rats with a tracheal cannula, attenuating the inflammatory response by inhibiting NF-κB signaling. Our findings suggest that the anti-biofilm and anti-inflammatory activities of TPs render these naturally active compounds favorable candidates for the treatment of tracheal catheter-related infections.

The emerging role of Fusobacteria in carcinogenesis

The Fusobacterium genus comprises Gram-negative, obligate anaerobic bacteria that typically reside in the periodontium of the oral cavity, gastrointestinal tract, and female genital tract. The association of Fusobacterial spp. with colorectal tumours is widely accepted, with further evidence that this pathogen may also be implicated in the development of other malignancies. Fusobacterial spp. influence malignant cell behaviours and the tumour microenvironment in various ways, which can be related to the multiple surface adhesins expressed. These adhesins include Fap2 (fibroblast-activated protein 2), CpbF (CEACAM binding protein of Fusobacteria), FadA (Fusobacterium adhesin A) and FomA (Fusobacterial outer membrane protein A). This review outlines the influence of Fusobacteria in promoting cancer initiation and progression, impacts of therapeutic outcomes and discusses potential therapeutic interventions where appropriate.

Deciphering the mechanism of anti-quorum sensing post-biotic mediators against Streptococcus mutans

OBJECTIVE

Glucosyltransferases (Gtfs) and quorum sensing (QS) mediated transduction genes play critical roles in the pathogenesis of Streptococcus mutan-mediated dental caries. Therefore, targeting gtfs and QS-mediated virulence genes have therefore emerged as an intriguing goal for efficient therapeutic approaches that block cariogenic biofilms.

METHODS

Post-biotic mediators (PMs) obtained from our previously isolated and characterized beneficial bacteria Enterobacter colacae PS-74 was assessed for its antibiofilm potential against S. mutans. According to the transcriptome method, qRT-PCR analysis was performed against virulence genes. For microscopic visualization, SEM and CLSM analyses were used to confirm the inhibitory effects of PMs.

RESULTS

PMs dramatically reduced the expression of QS signal transduction, glucan metabolism, and biofilm-regulated genes such gtfB, gtfC, ComDE, VicR, brpA in S. mutans, which validates the outcomes of in vitro result. Their unique metabolites may help to control biofilm formation by eluding antimicrobial resistance.

CONCLUSION

Considering the above findings, PMs may deem to be an innovative, alluring, and secure method for preventing dental caries due to their biological activity. Our study unravels the inhibitory effect of PMs, which will contribute to instruct drug design strategies for effective inhibition of S. mutans biofilms.

Antibacterial Effects of Ramulus mori Oligosaccharides against Streptococcus mutans

Ramulus mori has been widely used in traditional Chinese medicine because of its physiological activities, including antibacterial, anti-inflammatory, and antioxidant activities. Antimicrobial properties of Ramulus mori extract have been well described. However, no information is available regarding on Ramulus mori oligosaccharides (RMOS). The aim of this study was to investigate the effects of RMOS on the growth and virulence properties of the cariogenic bacterium Streptococcus mutans. The effects of RMOS on the biofilm structure and virulence gene expression of S. mutans were also evaluated, and the results were compared with the effects of commercial prebiotic galactooligosaccharides. RMOS were found to have an antibacterial effect against S. mutans, resulting in significant reductions in acid production, lactate dehydrogenase activity, adhesion, insoluble extracellular polysaccharide production, glucosyltransferase activity, and biofilm formation in a dose-dependent manner. Moreover, the biofilm structure was visibly damaged. A quantitative real-time PCR assay revealed downregulation of virulence gene-regulated acid production, polysaccharide production, adhesion, biofilm formation, and quorum sensing. These findings suggest that RMOS may be a promising natural product for the prevention of dental caries.

Comparing proteome changes involved in biofilm formation by Streptococcus mutans after exposure to sucrose and starch

Streptococcus mutans is a main organism of tooth infections including tooth decay and periodontitis. The aim of this study was to assess the influence of sucrose and starch on biofilm formation and proteome profile of S. mutans ATCC 35668 strain. The biofilm formation was assessed by microtiter plating method. Changes in bacterial proteins after exposure to sucrose and starch carbohydrates were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The biofilm formation of S. mutans was increased to 391.76% in 1% sucrose concentration, 165.76% in 1% starch, and 264.27% in the 0.5% sucrose plus 0.5% starch in comparison to biofilm formation in the media without sugars. The abundance of glutamines, adenylate kinase, and 50S ribosomal protein L29 was increased under exposure to sucrose. Upregulation of lactate utilization protein C, 5-hydroxybenzimidazole synthase BzaA, and 50S ribosomal protein L16 was formed under starch exposure. Ribosome-recycling factor, peptide chain release factor 1, and peptide methionine sulfoxide reductase MsrB were upregulated under exposure to sucrose in combination with starch. The results demonstrated that the carbohydrates increase microbial pathogenicity. In addition, sucrose and starch carbohydrates can induce biofilm formation of S. mutans via various mechanisms such as changes in the expression of special proteins.

Sodium New Houttuyfonate Inhibits Cancer-Promoting Fusobacterium nucleatum (Fn) to Reduce Colorectal Cancer Progression

Colorectal cancer (CRC) is a major cause of morbidity and mortality worldwide. Recent studies showed that the common anaerobe Fusobacterium nucleatum (Fn) is closely associated with a higher risk for carcinogenesis, metastasis, and chemoresistance of CRC. However, there is no specific antimicrobial therapy for CRC treatment. Herbal medicine has a long history of treating diseases with remarkable effects and is attracting extensive attention. In this study, we tested six common phytochemicals for their antimicrobial activities against Fn and whether anti-Fn phytochemicals can modulate CRC development associated with Fn. Among these antimicrobials, we found that SNH showed the highest antimicrobial activity and little cytotoxicity toward cancer cells and normal cells in vitro and in vivo. Mechanistically, SNH may target membrane-associated FadA, leading to FadA oligomerization, membrane fragmentation and permeabilization. More importantly, SNH blocked the tumor-promoting activity of Fn and Fn-associated cancer-driven inflammation, thus improving the intestinal barrier damaged by Fn. SNH reduced Fn load in the CRC-cells-derived mice xenografts with Fn inoculation and significantly inhibited CRC progression. Our data suggest that SNH could be used for an antimicrobial therapy that inhibits Fn and cancer-driven inflammation of CRC. Our results provide an important foundation for future gut microbiota-targeted clinical treatment of CRC.

Natural products from traditional medicine as promising agents targeting at different stages of oral biofilm development

Oral cavity is an ideal habitat for more than 1,000 species of microorganisms. The diverse oral microbes form biofilms over the hard and soft tissues in the oral cavity, affecting the oral ecological balance and the development of oral diseases, such as caries, apical periodontitis, and periodontitis. Currently, antibiotics are the primary agents against infectious diseases; however, the emergence of drug resistance and the disruption of oral microecology have challenged their applications. The discovery of new antibiotic-independent agents is a promising strategy against biofilm-induced infections. Natural products from traditional medicine have shown potential antibiofilm activities in the oral cavity with high safety, cost-effectiveness, and minimal adverse drug reactions. Aiming to highlight the importance and functions of natural products from traditional medicine against oral biofilms, here we summarized and discussed the antibiofilm effects of natural products targeting at different stages of the biofilm formation process, including adhesion, proliferation, maturation, and dispersion, and their effects on multi-species biofilms. The perspective of antibiofilm agents for oral infectious diseases to restore the balance of oral microecology is also discussed.

Effects of Simulated Microgravity on the Physiology of Stenotrophomonas maltophilia and Multiomic Analysis

Many studies have shown that the space environment plays a pivotal role in changing the characteristics of conditional pathogens, especially their pathogenicity and virulence. However, Stenotrophomonas maltophilia, a type of conditional pathogen that has shown to a gradual increase in clinical morbidity in recent years, has rarely been reported for its impact in space. In this study, S. maltophilia was exposed to a simulated microgravity (SMG) environment in high-aspect ratio rotating-wall vessel bioreactors for 14days, while the control group was exposed to the same bioreactors in a normal gravity (NG) environment. Then, combined phenotypic, genomic, transcriptomic, and proteomic analyses were conducted to compare the influence of the SMG and NG on S. maltophilia. The results showed that S. maltophilia in simulated microgravity displayed an increased growth rate, enhanced biofilm formation ability, increased swimming motility, and metabolic alterations compared with those of S. maltophilia in normal gravity and the original strain of S. maltophilia. Clusters of Orthologous Groups (COG) annotation analysis indicated that the increased growth rate might be related to the upregulation of differentially expressed genes (DEGs) involved in energy metabolism and conversion, secondary metabolite biosynthesis, transport and catabolism, intracellular trafficking, secretion, and vesicular transport. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that the increased motility might be associated the upregulation of differentially expressed proteins (DEPs) involved in locomotion, localization, biological adhesion, and binding, in accordance with the upregulated DEGs in cell motility according to COG classification, including pilP, pilM, flgE, flgG, and ronN. Additionally, the increased biofilm formation ability might be associated with the upregulation of DEPs involved in biofilm formation, the bacterial secretion system, biological adhesion, and cell adhesion, which were shown to be regulated by the differentially expressed genes (chpB, chpC, rpoN, pilA, pilG, pilH, and pilJ) through the integration of transcriptomic and proteomic analyses. These results suggested that simulated microgravity might increase the level of corresponding functional proteins by upregulating related genes to alter physiological characteristics and modulate growth rate, motility, biofilm formation, and metabolism. In conclusion, this study is the first general analysis of the phenotypic, genomic, transcriptomic, and proteomic changes in S. maltophilia under simulated microgravity and provides some suggestions for future studies of space microbiology.