Research progress on the pathogenicity of Porphyromonas gingivalis clinical strains / 口腔疾病防治

@#Porphyromonas gingivalis (P. gingivalis) is closely related to the occurrence and development of periodontitis. It is considered to be one of the important pathogens leading to alveolar bone resorption. At present, research on P. gingivalis mostly adopts standard laboratory strains whose genetic characteristics have been confirmed, are guaranteed and are traceable, such as ATCC 33277. The virulence phenotypes (endotoxin, firmbria, etc.) of clinically extracted isolates are quite different from those of standard strains, and the pathogenic effects and ability of the host are also widely different. In addition, P. gingivalis is considered to have a significant correlation with a variety of systemic diseases, and the virulence characteristics and pathogenic ability of different strains will have different effects on systemic diseases. However, at present, there is a lack of research on clinical strains and standard strains, and there is a lack of systematic comparison between the two sources of bacteria. In this paper, the differences in the virulence phenotypes and pathogenic effects between clinical isolates and standard strains of P. gingivalis in the last 5-10 years are reviewed. The aim is to elucidate the important virulence gene loci in the P. gingivalis gene sequence, which will play an important role in improving therapeutic methods and the development of related drugs.

Research progress on the relationship between free sugars and caries / 口腔疾病防治

@#Caries is a chronic infectious disease that occurs in the hard tissues of teeth. The interaction of oral microorganisms, host, food and time leads to the occurrence and progression of caries. Free sugar is an important food factor in the occurrence of dental caries. This paper reviews the research progress on the relationship between free sugar and caries in recent years, providing a reference for further clarifying the mechanism of the occurrence and progression of caries caused by free sugar and exploring the methods of caries prevention. The cariogenic mechanism of free sugar is multifaceted. Free sugar can not only be used by oral microorganisms in dental plaque biofilms to produce acid and synthesize intracellular and extracellular polysaccharides but also cause an imbalance in oral microecology and enhance gene expression related to the cariogenic toxicity of oral microorganisms. Based on the correlation between free sugar and caries, it is important to limit the intake amount and frequency of free sugar to prevent caries. This can be achieved mainly by formulating public health policies for reducing sugar, creating a low-sugar family environment with good eating habits, using sugar substitutes and using fluoride. There are few studies on the relationship between free sugar and oral microecology. More research is needed to better understand the effect of free sugar on oral microecology and its mechanism and to validate the caries-preventing effect of various sugar reduction measures. We believe such studies would open up new avenues for the effective prevention of caries.

Research progress on Streptococcus mutans phages in the prevention of dental caries / 口腔疾病防治

@#The Streptococcus mutans (S. mutans) phage, as one of the principal pathogenic bacteria of dental caries, is a main cause of the formation and development of dental caries due to its overproliferation in dental plaque biofilms. Bacterial viruses, also known as bacteriophages, have the capability of specifically infecting bacteria and effectively degrading bacterial biofilms. S. mutans phages, therefore, may prevent and control caries. Therapy based on phages has been applied in many fields, but the application of S. mutans phages in caries remains exploratory. This article will review the research progress of S. mutans phages in clinical caries prevention, aiming to provide a new idea for the clinical prevention of caries. The results of the literature review show that the living bacteriophage system has the advantages of high specificity, high affinity and good safety. However, due to its unstable structure, it can be processed into a more stable formulation by freeze-drying, spray drying, adding stability enhancers, or incorporating bacteriophages into ointments, biodegradable polymer matrices or particles to a certain extent to improve stability. The lysozyme produced by phages can digest the bacterial cell wall and release the assembled phage particles, which effectively cleave biofilms. In addition, the antigen binding fragment library for cariogenic pathogens was screened by phage display technology, and the purpose of caries prevention and treatment was achieved by passive immunization of antigen binding fragments. However, the host range of bacteriophages is narrow, so this kind of problem can be overcome by phage combined with traditional therapy or other drug use or cocktail therapy with multiple phages in clinical caries prevention and control.

Association of bone mineral density with chronic obstructive pulmonary disease in postmenopausal women

Abstract Background Osteoporosis (OP) is common in patients with chronic obstructive pulmonary disease (COPD). The relationship between OP and COPD has been primarily studied in male patients, and few reports are available in postmenopausal women. Objective The purpose of this study was to investigate the association between bone mineral density (BMD) and COPD in postmenopausal women. Methods This cross-sectional study included 133 clinically stable female ex-smokers with confirmed COPD, and 31 age-matched “ex-smoker” female controls. We analyzed groups according to their airway obstruction category. BMD was measured on dual-energy X-ray absorptiometry images of the left femoral neck. Results Patients with COPD had lower T-scores and higher prevalence of osteopenia/OP than the control group. In the COPD group, the airway obstruction category was significantly associated with the T-score after adjustment for confounders. Multivariate logistic regression analysis showed COPD was an independent marker for increased risk of osteopenia/OP in postmenopausal women. Conclusions COPD and airway obstruction category were strongly related to BMD. Postmenopausal women with COPD, especially those with severe airway obstruction, had a higher prevalence rate and a higher risk of osteopenia and OP than female controls without COPD.

A multiomics approach to study the associations between microbial communities and functions and dental caries / 口腔疾病防治

@#The pathogenic mechanisms by which oral microbial communities affect the occurrence and development of dental caries remain unclear. Applications that make use of high-through put sequencing technologies and metaomics approaches to research dental caries etiology can provide new ideas about disease prevention and treatment. In this article, we review advanced research presented in metaomics studies, including genomic, metagenomic, metatranscriptomic, metaproteomic and metabolomics studies of dental caries.

Research progress of microbial biomarkers of early childhood caries / 口腔疾病防治

@#The microorganisms in a healthy child’s oral environment survive in certain proportions and form a stable dynamic balance with the host. If this balance is disrupted, some of the microorganisms become cariogenic microbes and cause early childhood caries (ECC). The changes of cariogenic microbes in this process could be used as biomarkers to assess the caries risk of children and forecast the development of ECC. The relative indices of Streptococcus mutans and the closely related Candida albicans, Bifidobacterium and Streptococci sanguinis may be used as biomarkers to diagnose the susceptibility of children to caries. The detection rate and detection level of Lactobacillus may provide a reference for judging the rate of ECC development.

The Oral Microbiome Bank of China / 国际口腔科学杂志·英文版

The human microbiome project (HMP) promoted further understanding of human oral microbes. However, research on the human oral microbiota has not made as much progress as research on the gut microbiota. Currently, the causal relationship between the oral microbiota and oral diseases remains unclear, and little is known about the link between the oral microbiota and human systemic diseases. To further understand the contribution of the oral microbiota in oral diseases and systemic diseases, a Human Oral Microbiome Database (HOMD) was established in the US. The HOMD includes 619 taxa in 13 phyla, and most of the microorganisms are from American populations. Due to individual differences in the microbiome, the HOMD does not reflect the Chinese oral microbial status. Herein, we established a new oral microbiome database-the Oral Microbiome Bank of China (OMBC, http://www.sklod.org/ombc ). Currently, the OMBC includes information on 289 bacterial strains and 720 clinical samples from the Chinese population, along with lab and clinical information. The OMBC is the first curated description of a Chinese-associated microbiome; it provides tools for use in investigating the role of the oral microbiome in health and diseases, and will give the community abundant data and strain information for future oral microbial studies.

Influence of Helicobacter pylori culture supernatant on the ecological balance of a dual-species oral biofilm

Abstract Dental caries is a chronic progressive disease occurring in the tooth hard tissue due to multiple factors, in which bacteria are the initial cause. Both Streptococcus mutans and Streptococcus sanguinis are main members of oral biofilm. Helicobacter pylori may also be detected in dental plaque, playing an important role in the development of dental caries. Objective The aim of this study was to investigate the effect of H. pylori culture supernatant on S. mutans and S. sanguinis dual-species biofilm and to evaluate its potential ability on affecting dental health. Material and methods The effect of H. pylori supernatant on single-species and dual-species biofilm was measured by colony forming units counting and fluorescence in situ hybridization (FISH) assay, respectively. The effect of H. pylori supernatant on S. mutans and S. sanguinis extracellular polysaccharides (EPS) production was measured by both confocal laser scanning microscopy observation and anthrone-sulfuric acid method. The effect of H. pylori supernatant on S. mutans gene expression was measured by quantitative real-time PCR (qRT-PCR) assays. Results H. pylori supernatant could inhibit both S. mutans and S. sanguinis biofilm formation and EPS production. S. sanguinis inhibition rate was significantly higher than that of S. mutans. Finally, S. mutans bacteriocin and acidogenicity related genes expression were affected by H. pylori culture supernatant. Conclusion Our results showed that H. pylori could destroy the balance between S. mutans and S. sanguinis in oral biofilm, creating an advantageous environment for S. mutans, which became the dominant bacteria, promoting the formation and development of dental caries.