Differences of protein expression in enterococcus faecalis biofilm during resistance to environmental pressures.

BACKGROUND: Enterococcus faecalis biofilm was frequently found on the failed treated root canal wall, which survived by resisting disinfectant during endodontic treatment.Many researches have been conducted to explore the mechanisms of persistence of this pathogen in unfavorable conditions. However, no comprehensive proteomics studies have been conducted to investigate stress response in Enterococcus faecalis caused by alkali and NaOCl. OBJECTIVE: Enterococcus faecalis (E.f) has been recognized as a main pathogen of refractory apical periodontitis, its ability to withstand environmental pressure is the key to grow in the environment of high alkaline and anti-bacterial drug that causes chronic infection in the root canal. This study aims to focus on the protein expression patterns of E.f biofilm under extreme pressure environment". METHODS: Enterococcus faecalis biofilm model was established in vitro. Liquid Chromatograph-Mass Spectrometer (LC-MS/MS)-based label free quantitative proteomics approach was applied to compare differential protein expression under different environmental pressures (pH 10 and 5% sodium hypochlorite (NaOCl)). And then qPCR and Parallel Reaction Monitoring Verification (PRM) were utilized to verify the consequence of proteomics. RESULTS: The number of taxa in this study was higher than those in previous studies, demonstrating the presence of a remarkable number of proteins in the groups of high alkaline and NaOCl. Proteins involved in ATP-binding cassette (ABC) transporter were significantly enriched in experimental samples. We identified a total of 15 highly expressed ABC transporters in the high alkaline environment pressure group, with 7 proteins greater than 1.5 times. CONCLUSIONS: This study revealed considerable changes in expression of proteins in E.f biofilm during resistance to environmental pressures. The findings enriched our understanding of association between the differential expression proteins and environmental pressures.

[Research on histologic changes of periodontal tissue, testification of TNF-alpha and their relationship in diabetics rats].

OBJECTIVE: The histologic and TNF-alpha changes of the experimental periodontitis were studied in diabetic rat model in different periods. The mechanism of the occurring and developing of periodontitis was probed on the aspect of cytology. METHODS: The diabetic rat models were established by injecting streptozotocin into its abdomen. The local stimulation was caused by tiring silk thread to teeth. The histologic changes of periodontium were observed at 6,9,and 12 weeks. The level of TNF-alpha was testified using immunohistochemistry method at 12 weeks. RESULTS: Periodontitis occurred in diabetic rats earlier than in non-diabetic ones. The destructions were more severe and more widely in diabetic rats than in non-diabetic ones. The level of TNF-alpha was higher in the experimental periodontium of diabetic rats than those non-diabetics. CONCLUSIONS: Diabetes mellitus has an accelerating effect on occurring and developing of periodontitis. When with diabetes, more cytokines were released, and cause the unbalance of ruin and repair and result in the enhancing of periodontitis.