Osteomodulin protects dental pulp stem cells from cisplatin-induced apoptosis in vitro.

Human dental pulp stem cells (hDPSCs) are considered promising multipotent cell sources for tissue regeneration. Regulation of apoptosis and maintaining the cell homeostasis is a critical point for the application of hDPSCs. Osteomodulin (OMD), a member of the small leucine-rich proteoglycan family, was proved an important regulatory protein of hDPSCs in our previous research. Thus, the role of OMD in the apoptosis of hDPSCs was explored in this study. The expression of OMD following apoptotic induction was investigated and then the hDPSCs stably overexpressing or knocking down OMD were established by lentiviral transfection. The proportion of apoptotic cells and apoptosis-relative genes and proteins were examined with flow cytometry, Hoechst staining, Caspase 3 activity assay, qRT-PCR and western blotting. RNA-Seq analysis was used to explore possible biological function and mechanism. Results showed that the expression of OMD decreased following the apoptotic induction. Overexpression of OMD enhanced the viability of hDPSCs, decreased the activity of Caspase-3 and protected hDPSCs from apoptosis. Knockdown of OMD showed the opposite results. Mechanistically, OMD may act as a negative modulator of apoptosis via activation of the Akt/Glycogen synthase kinase 3ß (GSK-3ß)/ß-Catenin signaling pathway and more functional and mechanistic possibilities were revealed with RNA-Seq analysis. The present study provided evidence of OMD as a negative regulator of apoptosis in hDPSCs. Akt/GSK-3ß/ß-Catenin signaling pathway was involved in this process and more possible mechanism detected needed further exploration. This anti-apoptotic function of OMD provided a promising application prospect for hDPSCs in tissue regeneration.

p300 and C/EBPß-regulated IKKß expression are involved in thrombin-induced IL-8/CXCL8 expression in human lung epithelial cells.

Asthma and chronic obstructive pulmonary disease (COPD) are common chronic lung inflammatory diseases. Thrombin and interleukin (IL)-8/C-X-C chemokine ligand 8 (CXCL8) play critical roles in lung inflammation. Our previous study showed that c-Src-dependent IκB kinase (IKK)/IκBα/nuclear factor (NF)-κB and mitogen-activated protein kinase kinase kinase 1 (MEKK1)/extracellular signal-regulated kinase (ERK)/ribosomal S6 protein kinase (RSK)-dependent CAAT/enhancer-binding protein ß (C/EBPß) activation are involved in thrombin-induced IL-8/CXCL8 expression in human lung epithelial cells. In this study, we aimed to investigate the roles of p300 and C/EBPß-reliant IKKß expression in thrombin-induced IL-8/CXCL8 expression. Thrombin-induced increases in IL-8/CXCL8-luciferase activity and IL-8/CXCL8 release were inhibited by p300 small interfering (siRNA). Thrombin-caused histone H3 acetylation was attenuated by p300 siRNA. Stimulation of cells with thrombin for 12h resulted in increases in IKKß expression and phosphorylation in human lung epithelial cells. However, thrombin did not affect p65 expression. Moreover, 12h of thrombin stimulation produced increases in IKKß expression and phosphorylation, and IκBα phosphorylation, which were inhibited by C/EBPß siRNA. Finally, treatment of cells with thrombin caused increases in p300 and C/EBPß complex formation, p65 and C/EBPß complex formation, and recruitment of p300, p65, and C/EBPß to the IL-8/CXCL8 promoter. These results imply that p300-dependent histone H3 acetylation and C/EBPß-regulated IKKß expression contribute to thrombin-induced IL-8/CXCL8 expression in human lung epithelial cells. Results of this study will help clarify C/EBPß signaling pathways involved in thrombin-induced IL-8/CXCL8 expression in human lung epithelial cells.

Characterization of oral bacterial diversity of irradiated patients by high-throughput sequencing.

The objective of this study was to investigate the compositional profiles and microbial shifts of oral microbiota during head-and-neck radiotherapy. Bioinformatic analysis based on 16S rRNA gene pyrosequencing was performed to assess the diversity and variation of oral microbiota of irradiated patients. Eight patients with head and neck cancers were involved in this study. For each patient, supragingival plaque samples were collected at seven time points before and during radiotherapy. A total of 147,232 qualified sequences were obtained through pyrosequencing and bioinformatic analysis, representing 3,460 species level operational taxonomic units (OTUs) and 140 genus level taxa. Temporal variations were observed across different time points and supported by cluster analysis based on weighted UniFrac metrics. Moreover, the low evenness of oral microbial communities in relative abundance was revealed by Lorenz curves. This study contributed to a better understanding of the detailed characterization of oral bacterial diversity of irradiated patients.

Exploring the dynamic core microbiome of plaque microbiota during head-and-neck radiotherapy using pyrosequencing.

Radiotherapy is the primary treatment modality used for patients with head-and-neck cancers, but inevitably causes microorganism-related oral complications. This study aims to explore the dynamic core microbiome of oral microbiota in supragingival plaque during the course of head-and-neck radiotherapy. Eight subjects aged 26 to 70 were recruited. Dental plaque samples were collected (over seven sampling time points for each patient) before and during radiotherapy. The V1-V3 hypervariable regions of bacterial 16S rRNA genes were amplified, and the high-throughput pyrosequencing was performed. A total of 140 genera belonging to 13 phyla were found. Four phyla (Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria) and 11 genera (Streptococcus, Actinomyces, Veillonella, Capnocytophaga, Derxia, Neisseria, Rothia, Prevotella, Granulicatella, Luteococcus, and Gemella) were found in all subjects, supporting the concept of a core microbiome. Temporal variation of these major cores in relative abundance were observed, as well as a negative correlation between the number of OTUs and radiation dose. Moreover, an optimized conceptual framework was proposed for defining a dynamic core microbiome in extreme conditions such as radiotherapy. This study presents a theoretical foundation for exploring a core microbiome of communities from time series data, and may help predict community responses to perturbation as caused by exposure to ionizing radiation.

Effects of intensity-modulated radiotherapy on human oral microflora.

This study aimed to evaluate changes in the biodiversity of the oral microflora of patients with head and neck cancer treated with postoperative intensity-modulated radiotherapy (IMRT) or conventional radiotherapy (CRT). Pooled dental plaque samples were collected during the radiation treatment from patients receiving IMRT (n = 13) and CRT (n = 12). Denaturing gradient gel electrophoresis (DGGE) was used to analyze the temporal variation of these plaque samples. The stimulated and unstimulated salivary flow rates were also compared between IMRT and CRT patients. Reductions in the severity of hyposalivation were observed in IMRT patients compared with CRT patients. We also observed that the temporal stability of the oral ecosystem was significantly higher in the IMRT group (69.96 ± 7.82%) than in the CRT group (51.98 ± 10.45%) (P < 0.05). The findings of the present study suggest that IMRT is more conducive to maintaining the relative stability of the oral ecosystem than CRT.

[In vitro study of the effect of 11 kinds of natural drugs on the growth and acid production of Lactobacillus].

PURPOSE: To study the effect of 11 different natural drugs on the growth and acid production of Lactobacillus, as a preparation for screening an effective agent to mediate the balance of oral microflora. METHODS: Lactobacillus AC413 was chosen as the experimental bacterium. Eleven kinds of drugs, such as Rhizoma Chuanxiong, Surgentodoxa cuneata and Galla Chinensis were extracted by means of maceration, percolation and reflux extraction. The values of MIC of various extracts were measured. Then, different experimental media containing various extracts were prepared. The concentration of the extracts was lower than the MIC of the drug and the initial pH of the medium was 7.4. Lactobacillus was cultured in the medium for 48 hours, and finally the rest pH was measured. One-way ANOVA was used for statistical analysis. RESULTS: When the concentration of the drugs was lower than 8.000mg/ml, Tea polyphenols, Catechu, Galla Chinensis, Radix et Rhizoma Rhei and Nidus Vespae can inhibit the growth of Lactobacillus effectively. Tea polyphenols, Nidus Vespae, Radix Scuteilariae, Galla Chinensis and Surgentodoxa cuneata can inhibit the acid production of Lactobacillus effectively, Rhizoma Chuanxiong, Radix et Rhizoma Rhei, Semen Arecae and Catechu have no preliminary effect on it, but Surgentodoxa Cuneata and Radix Angelicae Pubescentis can increase it. CONCLUSION: Tea polyphenols, Catechu, Galla Chinensis, Radix et Rhizoma Rhei and Nidus Vespae can inhibit the growth of Lactobacillus effectively, and Tea polyphenols, Radix et Rhizoma Rhei, Nidus Vespae, Radix Scuteilariae, Galla Chinensis and Surgentodoxa Cuneata can inhibit the acid production of Lactobacillus effectively.

[A comparison of the activities of membrane-bound, proton translocating ATPases between Streptococcus mutans fluoride-resistant and their parent strains].

PURPOSE: To figure out the reason for increased acid tolerance of Ingbritt-FR, the fluoride-resistant strain of Streptococcus mutans Ingbritt, by determining and comparing the H(+)-ATPase activities of both fluoride-resistant and their parental strains. METHODS: The permeabilized cells of S. mutans Ingbritt and Ingbritt-FR were prepared by treating them with 10% toluene and then two cycles of freezing and thawing. The permeabilized cells were used for ATPase assay by adding them to the reaction mixture which contained 50mM Tris-maleate buffer (pH 6.0), 10 mM MgSO4 and 5 mM ATP. ATPase activity was assessed by measuring inorganic phosphate released from ATP hydrolysis.Two-way ANOVA was used for statistical analysis. RESULTS: The activities of H(+)-ATPase of Ingbritt-FR were 308.48, 136.67, and 82.80 micromol Pi/g cell dry weight/min, at 10, 20, and 60 minutes respectively, significantly higher than those of their parent strain: 104.77, 64.69, and 30.7 (P<0.01). The enzyme activities were decreasing with time. CONCLUSIONS: The higher ATPase activity of fluoride-resistant mutant of S. mutans Ingbritt may account for the increased acid tolerance of this organism, and the increment of ATPase activity and acid tolerance of fluoride-resistant strain is likely to increase the cariogenic potential of S. mutans after fluoride-resistant mutation.