Stimulus-responsive biomaterials for Helicobacter pylori eradication.

BACKGROUND: Helicobacter pylori (H. pylori), the only bacterium classified as a type I (definite) carcinogen, is strongly associated with the development of gastric inflammation and adenocarcinoma. It infects the stomach of approximately half of the global population, equivalent to nearly 4.4 billion people. However, due to physiological barriers in the stomach, microbial barriers and increased antibiotic resistance, the therapeutic efficiency of standard antibiotic therapy is limited and cannot meet the clinical needs in some areas. Combining stimulus-responsive biomaterials with certain stimuli is an emerging antibacterial strategy. Stimulus-responsive biomaterials can respond to chemical, biological or physical cues in the environment with corresponding changes in their own properties and functions, highlighting a more intelligent, targeting and efficient aspect for H. pylori therapy. AIM OF REVIEW: This review describes the critical obstacles in the current treatment of H. pylori, summarizes the recent advances in stimulus-responsive biomaterials against H. pylori by elucidating their working mechanisms and antibacterial performances under different types of stimuli (pH, enzymes, light, magnetic and ultrasound irradiations), and attempts to analyze the future prospects of such smart biomaterial for H. pylori eradication. Key Scientific Concepts of Review: Any characteristic property or change in the biomilieu at the H. pylori infected site (endogenous stimuli) or specific iatrogenic conditions in vitro (exogenous stimuli) can act as cues to activate or potentiate the antibacterial activity of responsive biomaterials. The responsiveness of these materials to endogenous stimuli enhances antimicrobial targeting, and makes physiological barriers that would otherwise hinder conventional H. pylori therapies a key factor in facilitating antibacterial effects. The responsiveness to exogenous stimuli greatly prolongs the action time of antimicrobial materials and pinpoints the site of infection, thereby reducing toxic side effects. These findings pave the way for the development of more precise and effective anti-H. pylori treatment.

Artemisinins inhibit oral candidiasis caused by Candida albicans through the repression on its hyphal development.

Candida albicans is the most abundant fungal species in oral cavity. As a smart opportunistic pathogen, it increases the virulence by switching its forms from yeasts to hyphae and becomes the major pathogenic agent for oral candidiasis. However, the overuse of current clinical antifungals and lack of new types of drugs highlight the challenges in the antifungal treatments because of the drug resistance and side effects. Anti-virulence strategy is proved as a practical way to develop new types of anti-infective drugs. Here, seven artemisinins, including artemisinin, dihydroartemisinin, artemisinic acid, dihydroartemisinic acid, artesunate, artemether and arteether, were employed to target at the hyphal development, the most important virulence factor of C. albicans. Artemisinins failed to affect the growth, but significantly inhibited the hyphal development of C. albicans, including the clinical azole resistant isolates, and reduced their damage to oral epithelial cells, while arteether showed the strongest activities. The transcriptome suggested that arteether could affect the energy metabolism of C. albicans. Seven artemisinins were then proved to significantly inhibit the productions of ATP and cAMP, while reduced the hyphal inhibition on RAS1 overexpression strain indicating that artemisinins regulated the Ras1-cAMP-Efg1 pathway to inhibit the hyphal development. Importantly, arteether significantly inhibited the fungal burden and infections with no systemic toxicity in the murine oropharyngeal candidiasis models in vivo caused by both fluconazole sensitive and resistant strains. Our results for the first time indicated that artemisinins can be potential antifungal compounds against C. albicans infections by targeting at its hyphal development.

Effects of Bio-Aging on Mechanical Properties and Microbial Behavior of Different Resin Composites.

Under challenging oral environments, the overall performance of resin composites is affected by bio-aging. This study investigated the effects of saliva biofilm-induced bio-aging on the mechanical properties and microbial behavior of composites with different filler types. Microhybrid, nanohybrid, nano-filled and nano-filled flowable composites were bio-aged with saliva biofilm for 30 days. Surface morphology, roughness, mechanical and aesthetic properties were determined. A 48 h saliva biofilm model was used to evaluate the microbial behavior of different composites in vitro. Biofilm metabolic activity, lactic acid production and live/dead bacterial staining were tested. Six volunteers were selected to wear intra-oral appliances with composite slabs for 24 h and biofilms were collected and analyzed using 16S rRNA sequencing to assess the biofilm formation over those materials in situ. Although there were increasing trends, surface roughness, water resorption and material solubility had no significant changes for all groups after bio-aging (p > 0.05). There were no significant changes in elastic modulus for all groups after aging (p > 0.05). However, a decrease in flexural strength in all groups was observed (p < 0.05), except for the nanoflow composite group (p > 0.05). The Vickers hardness remained stable in all groups after aging (p > 0.05), except for the nano-filled group (p < 0.05). The nanoflow composite showed distinct color changes compared to the micro-hybrid group after aging (p < 0.05). Biofilm metabolic activity and lactic acid production in vitro increased slightly after bio-aging in all groups, but with no statistical significance (p > 0.05). The Shannon index diversity of biofilms in situ decreased after aging (p < 0.05), while no significant difference was shown in species composition at the genus level in all groups (p > 0.05). Resin composites with different sized fillers displayed a relatively stable mechanical performance and uncompromised microbial behavior both in vitro and in situ after 30 days of bio-aging. Based on the results, composites with different filler types can be selected flexibly according to clinical needs. However, a longer time for bio-aging is still needed to confirm the mechanical properties and microbial behaviors of composites in the long run.

The CD47-SIRPα axis is a promising target for cancer immunotherapies.

Cluster of differentiation 47(CD47) is a transmembrane protein that is ubiquitously found on the surface of many cells in the body and uniquely overexpressed by both solid and hematologic malignant cells. CD47 interacts with signal-regulatory protein α (SIRPα), to trigger a "don't eat me" signal and thereby achieve cancer immune escape by inhibiting macrophage-mediated phagocytosis. Thus, blocking the CD47-SIRPα phagocytosis checkpoint, for release of the innate immune system, is a current research focus. Indeed, targeting the CD47-SIRPα axis as a cancer immunotherapy has shown promising efficacies in pre-clinical outcomes. Here, we first reviewed the origin, structure, and function of the CD47-SIRPα axis. Then, we reviewed its role as a target for cancer immunotherapies, as well as the factors regulating CD47-SIRPα axis-based immunotherapies. We specifically focused on the mechanism and progress of CD47-SIRPα axis-based immunotherapies and their combination with other treatment strategies. Finally, we discussed the challenges and directions for future research and identified potential CD47-SIRPα axis-based therapies that are suitable for clinical application.

The human oral - nasopharynx microbiome as a risk screening tool for nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a common head and neck cancer with a poor prognosis. There is an urgent need to develop a simple and convenient screening tool for early detection and risk screening of NPC. 139 microbial samples were collected from 40 healthy people and 39 patients with nasopharyngeal biopsy. A total of 40 and 39 oral, eight and 27 nasal cavity, nine and 16 nasopharyngeal microbial samples were collected from the two sets of individuals. A risk screening tool for NPC was established by 16S rDNA sequencing and random forest. Patients with nasopharyngeal biopsy had significantly lower nasal cavity and nasopharynx microbial diversities than healthy people. The beta diversity of the oral microbiome was significantly different between the two groups. The NPC screening tools based on nasopharyngeal and oral microbiomes have 88% and 77.2% accuracies, respectively. The nasopharyngeal biopsy patients had significantly higher Granulicatella abundance in their oral cavity and lower Pseudomonas and Acinetobacter in the nasopharynx than healthy people. This study established microbiome-based non-invasive, simple, no radiation, and low-cost NPC screening tools. Individuals at a high risk of NPC should be advised to seek further examination, which might improve the early detection of NPC and save public health costs.

The Clinical Potential of Oral Microbiota as a Screening Tool for Oral Squamous Cell Carcinomas.

Introduction: The oral squamous cell carcinoma (OSCC) is detrimental to patients' physical and mental health. The prognosis of OSCC depends on the early diagnosis of OSCC in large populations. Objectives: Here, the present study aimed to develop an early diagnostic model based on the relationship between OSCC and oral microbiota. Methods: Overall, 164 samples were collected from 47 OSCC patients and 48 healthy individuals as controls, including saliva, subgingival plaque, the tumor surface, the control side (healthy mucosa), and tumor tissue. Based on 16S rDNA sequencing, data from all the five sites, and salivary samples only, two machine learning models were developed to diagnose OSCC. Results: The average diagnostic accuracy rates of five sites and saliva were 98.17% and 95.70%, respectively. Cross-validations showed estimated external prediction accuracies of 96.67% and 93.58%, respectively. The false-negative rate was 0%. Besides, it was shown that OSCC could be diagnosed on any one of the five sites. In this model, Actinobacteria, Fusobacterium, Moraxella, Bacillus, and Veillonella species exhibited strong correlations with OSCC. Conclusion: This study provided a noninvasive and inexpensive way to diagnose malignancy based on oral microbiota without radiation. Applying machine learning methods in microbiota data to diagnose OSCC constitutes an example of a microbial assistant diagnostic model for other malignancies.

Novel dental implant modifications with two-staged double benefits for preventing infection and promoting osseointegration in vivo and in vitro.

Peri-implantitis are a major problem causing implant failure these days. Accordingly, anti-infection during the early stage and subsequent promotion of osseointegration are two main key factors to solve this issue. Micro-arc oxidation (MAO) treatment is a way to form an oxidation film on the surface of metallic materials. The method shows good osteogenic properties but weak antibacterial effect. Therefore, we developed combined strategies to combat severe peri-implantitis, which included the use of a novel compound, PD, comprising dendrimers poly(amidoamine) (PAMAM) loading dimethylaminododecyl methacrylate (DMADDM) as well as MAO treatment. Here, we explored the chemical properties of the novel compound PD, and proved that this compound was successfully synthesized, with the loading efficiency and encapsulation efficiency of 23.91% and 31.42%, respectively. We further report the two-stage double benefits capability of PD + MAO: (1) in the first stage, PD + MAO could decrease the adherence and development of biofilms by releasing DMADDM in the highly infected first stage after implant surgery both in vitro and in vivo; (2) in the second stage, PD + MAO indicated mighty anti-infection and osteoconductive characteristics in a rat model of peri-implantitis in vivo. This study first reports the two-staged, double benefits of PD + MAO, and demonstrates its potential in clinical applications for inhibiting peri-implantitis, especially in patients with severe infection risk.

The Oral Complications of COVID-19.

Background: COVID-19 is a novel coronavirus infectious disease associated with the severe acute respiratory syndrome. More and more patients are being cured due to the development of clinical guidelines for COVID-19 pneumonia diagnosis, treatment, and vaccines. However, the long-term impact of COVID-19 on patients after recovery is unclear. Currently available reports have shown that patients recovered from COVID-19 continue to experience health problems in respiratory and other organ systems. Oral problem is one of the important complications which has serious impacts on the rehabilitation and future quality of life, such as ageusia and macroglossia, but the oral complication is often being neglected. Aim of Review: From the perspective of stomatology, we summarized and elaborated in detail the types, pathogenesis of oral complications from COVID-19 patients after rehabilitation, and the reported prevention or treatment recommendations which may improve the COVID-19 patients associated oral diseases. Key Scientific Concepts of Review: 1) To understand the common oral complications and the mechanisms of the development of oral complications after the COVID-19 recovery; 2) To summary the practical strategies to prevent the oral complications and construct the rehabilitation plans for patients with oral complications.

Staphylococcus aureus induces COX-2-dependent proliferation and malignant transformation in oral keratinocytes.

The COX-2/PGE2 axis can play roles in mediating the progression of tumor. COX-2 induction was observed in oral cancer. In our previous study, we found Staphylococcus aureus, a pathogen prevalent in oral cancer, can activate the COX-2/PGE2 pathway in human oral keratinocyte (HOK) cells. Here, we investigated the proliferation of HOK cells affected by COX-2 induction and the role of COX-2 induction in the malignant transformation of HOK cells. We found S. aureus was able to facilitate HOK cell proliferation through upregulating COX-2 expression. With the induction of COX-2, expression of oral cancer-associated genes cyclin D1 was upregulated and p16 was downregulated. Transcriptome analysis showed that the "NF-kappa B signaling pathway" and "TNF signaling pathway" had the highest enrichment of differentially expressed genes (DEGs) with COX-2 over-expression. Seven upregulated genes (jun, tlr4, cxcl1, lif, cxcl3, tnfrsf1ß, and il1ß) in these two pathways were critical for the increased proliferation of HOK cells and might be associated with COX-2. Malignant transformation of cells was evaluated by soft agar colony formation assay and S. aureus infection promoted HOK cell colony formation. These results suggest the potential of S. aureus to induce the infection-associated malignant transformation of oral epitheliums through COX-2 activation.

A novel antibacterial resin-based root canal sealer modified by Dimethylaminododecyl Methacrylate.

Persistent apical periodontitis, mainly caused by microorganisms infections, represents a critical challenge for endodontists. Dimethylaminododecyl methacrylate (DMADDM) is a well-studied and potent antibacterial agent used in various studies described in the literature. The aim of this study is to develop a novel antibacterial root canal sealer by incorporating DMADDM into EndoREZ and investigate the properties of the resulting material. Different mass fractions (0, 1.25%, 2.5%, and 5%) of DMADDM were incorporated into EndoREZ and the cytotoxicity, apical sealing ability and solubility of the resulting material were evaluated. Furthermore, a direct contact test, determination of colony-forming units, a crystal violet assay, scanning electronic microscopy and live/dead bacteria staining were performed to evaluate the antibacterial effect of the sealer to multispecies bacteria (Enterococcus faecalis, Streptococcus gordonii, Actinomyces naeslundii, and Lactobacillus acidophilus), in planktonic cells or biofilms. Fluorescence in situ hybridization and quantitative real-time polymerase chain reaction were carried out to assess the composition of the multispecies biofilms. No difference on the cytotoxicity, apical sealing ability and solubility between sealers containing DMADDM (1.25%, 2.5%) and EndoREZ (0%) could be determined. However, when the mass fraction of DMADDM increased to 5%, significantly different properties were found compared to the 0% (p < 0.05) group. Moreover, incorporating DMADDM into the sealer could greatly improve the antibacterial properties of EndoREZ. In addition, the composition ratio of E. faecalis could be decreased in multispecies microecology in sealers containing DMADDM. Therefore, a EndoREZ sealer material containing DMADDM could be considered useful in clinical applications for preventing and treating persistent apical periodontitis.

Resveratrol attenuates neurological deficit and neuroinflammation following intracerebral hemorrhage.

Resveratrol (RESV) improves histopathological and behavioral outcomes in diseases of the central nervous system. However, to the best of our knowledge, there have been no studies investigating its neuroprotective effects on secondary brain injury following intracerebral hemorrhage (ICH). The aim of the present study was to evaluate the neuroprotective function of resveratrol following ICH. Male Sprague-Dawley rats were randomly divided into 3 groups: Sham, ICH and ICH+RESV groups. Rats underwent ICH and received an intraperitoneal injection of RESV daily. Rotarod and open field tests were performed to evaluate improvements in motor disturbance pre- and post-surgery. Rats were sacrificed following the final behavioral test; subsequently, neuron injury and cell death in the hippocampus and microglia activation in the cortex were determined using Nissl staining and ionized calcium binding adaptor molecule 1 immunofluorescence staining, respectively. Compared with the ICH group, rats treated with resveratrol for 2 weeks performed significantly better in behavioral tests. Furthermore, less neural damage in the hippocampus and decreased activation of microglia was observed in the ICH+RESV group. The results of the present study therefore indicate that resveratrol may alleviate secondary brain injury following ICH.

Effects of water and microbial-based aging on the performance of three dental restorative materials.

The objective of this study was to evaluate the performance changes of three restorative materials before and after three different aging treatments: storage in distilled water, Streptococcus mutans (S. mutans) and oral salivary microbes suspensions for one month. Resin composite (RC), giomer and glass ionomer cement (GIC) were chosen for aging procedures. Surface morphology, roughness average (Ra), color changes and mechanical properties were all determined before and after aging respectively. Biomass and metabolism difference of early attached biofilm on the material surface were tested through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactic acid measurement. The results showed that after S. mutans or salivary microbes aging treatments, GIC group displayed significant morphology changes, with Ra value significantly higher than that before aging (p < .001). Color changes of giomer and GIC group after S. mutans aging were not clinically acceptable. All materials after two microbial-based aging treatments had higher flexural strength than that before aging (p < .05). Giomer after salivary microbes aging had higher elastic modulus than the initial values (p < .05). Additionally, early attached biofilm biomass and lactic acid production in GIC group after S. mutans or salivary microbes aging were higher than that before aging (p < .05). While one-month water aging showed less influences on material performance to some extent. In conclusion, to better simulate the harsh oral environment, in vitro microbial-based aging models showed more advantages in evaluating dental restorative materials' degradation over time.

Effects of different substrates/growth media on microbial community of saliva-derived biofilm.

The aims of this study were to investigate the effects of substrates (glass versus hydroxyapatite [HA]) and growth media (SHI medium versus a modified artificial saliva medium with cysteine) on the microbial community of saliva-derived biofilm in vitro. 16S rRNA gene sequencing technology was used to analyze the microbial community of saliva-derived biofilm cultured for 72 h anaerobically. The metagenomes of biofilms were predicted from the clusters of orthologous groups. No significant difference was found between the saliva-derived biofilms grown on HA and glass in ACE, Chao, Shannon and Simpson indices. The abundances of only a few bacteria on HA were significantly different from those on glass with a low relative abundance (<0.5%). Compared with the biofilms developed in a modified artificial saliva medium with cysteine, biofilms in SHI medium were significantly higher (P < 0.05) in diversity. Linear discriminant analysis coupled with effect size measurement showed that some obligate anaerobic genera (Lactobacillus, Veillonella, Porphyromonas and Leptotrichia) were more abundant in SHI medium biofilms. The biofilms grown in different media were also significantly different in predicted gene categories. In conclusion, the growth media, not the substrates, have significant effects on the microbial community of saliva-derived biofilm in vitro.

[Isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity].

OBJECTIVE: To establish a systematic method for isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity. METHODS: Samples of the saliva, dental plaque and periapical granulation tissue were collected from 20 subjects with healthy oral condition and from 8 patients with different oral diseases. The bacteria in the samples were identified by morphological identification, VITEK automatic microorganism identification and 16s rRNA gene sequencing. RESULTS: VITEK automatic microorganism identification and 16s rRNA gene sequencing showed an agreement rate of 22.39% in identifying the bacteria in the samples. We identified altogether 63 bacterial genus (175 species), among which Streptococcus, Actinomyces and Staphylococcus were the most common bacterial genus, and Streptococcus anginosus, Actinomyces oris, Streptococcus mutans and Streptococcus mitis were the most common species. Streptococcus anginosus was commonly found in patients with chronic periapical periodontitis. Streptococcus intermedius and Staphylococcus aureus were common in patients with radiation caries, and in patients with rampant caries, Streptococcus mutans was found at considerably higher rate than other species. CONCLUSION: Aerobic and facultative anaerobic bacteria are commonly found in the oral cavity, and most of them are gram-positive. 16s rRNA gene sequencing is more accurate than VITEK automatic microorganism identification in identifying the bacteria.