Inhibited biofilm formation and improved antibacterial activity of a novel nanoemulsion against cariogenic Streptococcus mutans in vitro and in vivo.

The aim of this study was to prepare a novel nanoemulsion loaded with poorly water-soluble chlorhexidine acetate (CNE) to improve its solubility, and specifically enhance the antimicrobial activity against Streptococcus mutans in vitro and in vivo. In this study, a novel CNE nanoemulsion with an average size of 63.13 nm and zeta potential of -67.13 mV comprising 0.5% CNE, 19.2% Tween 80, 4.8% propylene glycol, and 6% isopropyl myristate was prepared by the phase inversion method. Important characteristics such as the content, size, zeta potential, and pH value of CNE did not change markedly, stored at room temperature for 1 year. Also, compared with chlorhexidine acetate water solution (CHX), the release profile results show that the CNE has visibly delayed releasing effect in both phosphate-buffered saline and artificial saliva solutions (P<0.005). The minimum inhibitory concentration and minimum bactericidal concentration of CHX for S. mutans (both 0.8 µg/mL) are both two times those of CNE (0.4 µg/mL). Besides, CNE of 0.8 µg/mL exhibited fast-acting bactericidal efficacy against S. mutans, causing 95.07% death within 5 minutes, compared to CHX (73.33%) (P<0.01). We observed that 5 mg/mL and 2 mg/mL CNE were both superior to CHX, significantly reducing oral S. mutans numbers and reducing the severity of carious lesions in Sprague Dawley rats (P<0.05), in an in vivo test. CNE treatment at a concentration of 0.2 µg/mL inhibited biofilm formation more effectively than CHX, as indicated by the crystal violet staining method, scanning electron microscopy, and atomic force microscopy. The cell membrane of S. mutans was also severely disrupted by 0.2 µg/mL CNE, as indicated by transmission electron microscopy. These results demonstrated that CNE greatly improved the solubility and antimicrobial activity of this agent against S. mutans both in vitro and in vivo. This novel nanoemulsion is a promising medicine for preventing and curing dental caries.

Systemic immunization with an epitope-based vaccine elicits a Th1-biased response and provides protection against Helicobacter pylori in mice.

Vaccine-mediated Th1-biased CD4+ T cell responses have been shown to be crucial for protection against Helicobacter pylori (H. pylori). In this study, we investigated whether a vaccine composed of CD4+ T cell epitopes together with Th1 adjuvants could confer protection against H. pylori in a mouse model. We constructed an epitope-based vaccine, designated Epivac, which was composed of predicted immunodominant CD4+ T cell epitopes from H. pylori adhesin A (HpaA), urease B (UreB) and cytotoxin-associated gene A product (CagA). Together with four different Th1 adjuvants, Epivac was administered subcutaneously and the prophylactic potential was examined. Compared to non-immunized mice, immunization with Epivac alone or with a Th1 adjuvant significantly reduced H. pylori colonization, and better protection was observed when an adjuvant was used. Immunized mice exhibited a strong local and systemic Th1-biased immune response, which may contribute to the inhibition of H. pylori colonization. Though a significant specific antibody response was induced by the vaccine, no correlation was found between the intensity of the humoral response and the protective effect. Our results suggest that a vaccine containing CD4+ T cell epitopes is a promising candidate for protection against H. pylori infection.

Plasma microRNAs, miR-223, miR-21 and miR-218, as novel potential biomarkers for gastric cancer detection.

BACKGROUND: MicroRNAs (miRNAs), endogenous small non-coding RNAs, are stably detected in human plasma. Early diagnosis of gastric cancer (GC) is very important to improve the therapy effect and prolong the survival of patients. We aimed to identify whether four miRNAs (miR-223, miR-21, miR-218 and miR-25) closely associated with the tumorigenesis or metastasis of GC can serve as novel potential biomarkers for GC detection. METHODOLOGY: We initially measured the plasma levels of the four miRNAs in 10 GC patients and 10 healthy control subjects by quantitative reverse transcription polymerase chain reaction (qRT-PCR), and then compared plasma miRNA results with the expressions in cancer tissues from eight GC patients. Finally, the presence of miR-223, miR-21 and miR-218 in the plasma was validated in 60 GC patients and 60 healthy control subjects, and the areas under the receiver operating characteristic (ROC) curves of these miRNAs were analyzed. RESULTS: We found that the plasma levels of miR-223 (P<0.001) and miR-21 (P<0.001) were significantly higher in GC patients than in healthy controls, while miR-218 (P<0.001) was significantly lower. The ROC analyses yielded the AUC values of 0.9089 for miR-223, 0.7944 for miR-21 and 0.7432 for miR-218, and combined ROC analysis revealed the highest AUC value of 0.9531 in discriminating GC patients from healthy controls. Moreover, the plasma levels of miR-223 (P<0.001) and miR-21 (P = 0.003) were significantly higher in GC patients with stage I than in healthy controls. Furthermore, the plasma levels of miR-223 were significantly higher in GC patients with helicobacter pylori (Hp) infection than those without (P = 0.014), and significantly higher in healthy control subjects with Hp infection than those without (P = 0.016). CONCLUSIONS: Plasma miR-223, miR-21 and miR-218 are novel potential biomarkers for GC detection.

CD8(+) T cells that produce interleukin-17 regulate myeloid-derived suppressor cells and are associated with survival time of patients with gastric cancer.

BACKGROUND & AIMS: CD8(+) T cells that produce interleukin (IL)-17 (Tc17 cells) promote inflammation and have been identified in tumors. We investigated their role in the pathogenesis of gastric cancer. METHODS: We used flow cytometry analyses to determine levels and phenotype of Tc17 cells in blood and tumor samples from 103 patients with gastric cancer. We performed multivariate analysis to identify factors associated with overall survival using the Cox proportional hazards model. CD8(+) T cells and monocytes were isolated and cocultured in an assay for induction of Tc17 cells. Tumor cells and myeloid-derived suppressor cells (MDSCs) were isolated and used in assays of Tc17 cell function. RESULTS: Tc17 cells with distinct cytokine and functional profiles were found in gastric tumor samples from patients. The percentage of Tc17 cells increased with tumor progression and was associated with overall survival time. Tumor-activated monocytes secreted IL-6, IL-1ß, and IL-23, which promoted development of Tc17 cell populations. Supernatants from cultured Tc17 cells induced production of the chemokine CXCL12 by tumor cells; this promoted CXCR4-dependent migration of MDSCs and impaired functions of anti-tumor CD8(+) cytotoxic T cells via a cell contact-dependent mechanism. CONCLUSIONS: Percentages of Tc17 cells in gastric tumors are associated with survival times of patients. These cells promote chemotaxis of MDSCs, which might promote tumor progression.

Therapeutic efficacy of oral immunization with attenuated Salmonella typhimurium expressing Helicobacter pylori CagA, VacA and UreB fusion proteins in mice model.

Therapeutic vaccination is a desirable alternative for controlling Helicobacter pylori (H. pylori) infection. In the present study, attenuated Salmonella vector vaccines were constructed that expressed fusion proteins complexed with H. pylori CagA, VacA and UreB in different arrangements, and their therapeutic efficacy was evaluated in H. pylori-infected mice. Oral therapeutic immunization with attenuated Salmonella, which expressed the fused protein CVU, significantly decreased H. pylori colonization in the stomach; protection was related to specific CD4(+) T cell Th1 type responses and serum IgG and mucosal sIgA antibody responses. These findings suggested that therapeutic efficacy was related to the arrangement of the fusion protein. It is possible that arrangement decides the expression of recombinant antigen in mice, and the latter results in different therapeutic efficacy. The attenuated Salmonella vector vaccine, which expressed the fused protein arrangement CVU, is superior to others, and could be a candidate vaccine against H. pylori.

Knockdown of ezrin via RNA interference suppresses Helicobacter pylori-enhanced invasion of gastric cancer cells.

BACKGROUND AND AIM: H. pylori interacts with gastric epithelial cells, which may activate signaling pathways important for gastric cancer invasion. Ezrin, a membrane cytoskeletal crosslinker protein, is well documented to regulate cell adhesion and cell motility. The aim of the present study was to determine whether ezrin is involved in H. pylori-induced cancer cell motility and invasion. METHODS: The VIL-2 of RNA interference plasmid vector and control plasmid vector were constructed. AGS (a human gastric adenocarcinoma cell line) cells were transfected by these plasmid vectors. The stable expression cell lines AGS(ezrin) was obtained by G418 resistance screening. The express levels of ezrin protein and the cellular invasive potential of four groups, including the AGS control, AGS(ezrin) control, AGS co-culture with H. pylori, AGS(ezrin) co-culture with H. pylori were detected. Meanwhile, the morphology, cell migration and adhesion were determined respectively. RESULTS: Co-culture with H. pylori stimulated AGS cell motility and invasion, up-regulated ezrin expression at the protein level and induced a Hummingbird phenotype. The silencing of ezrin expression suppressed the motility and invasion of gastric cancer cells and inversed the cell invasion phenotype and enhanced the ability for cell adhesion. CONCLUSION: Knockdown of ezrin by RNAi suppresses H. pylori-enhanced migration and invasion of gastric cancer cells. These findings indicate that ezrin may play a key role in the migration and invasion of gastric cancer cells, and thus may be a therapeutic target to prevent metastasis of gastric cancer promoted by H. pylori infection.

Protection against Helicobacter pylori infection by a trivalent fusion vaccine based on a fragment of urease B-UreB414.

A multivalent fusion vaccine is a promising option for protection against Helicobacter pylori infection. In this study, UreB414 was identified as an antigenic fragment of urease B subunit (UreB) and it induced an antibody inhibiting urease activity. Immunization with UreB414 partially protected mice from H. pylori infection. Furthermore, a trivalent fusion vaccine was constructed by genetically linking heat shock protein A (HspA), H. pylori adhesin A (HpaA), and UreB414, resulting in recombinant HspA-HpaA-UreB414 (rHHU). Its protective effect against H. pylori infection was tested in BALB/c mice. Oral administration of rHHU significantly protected mice from H. pylori infection, which was associated with H. pylori-specific antibody production and Th1/Th2-type immune responses. The results show that a trivalent fusion vaccine efficiently combats H. pylori infection, and that an antigenic fragment of the protein can be used instead of the whole protein to construct a multivalent vaccine.

Helicobacter pylori-induced Th17 responses modulate Th1 cell responses, benefit bacterial growth, and contribute to pathology in mice.

CD4(+) T cell responses are critical for the pathogenesis of Helicobacter pylori infection. The present study evaluated the role of the Th17 subset in H. pylori infection. H. pylori infection induced significant expression of IL-17 and IFN-gamma in mouse gastric tissue. IL-23 and IL-12 were increased in the gastric tissue and in H. pylori-stimulated macrophages. Cell responses were examined by intracellular staining for IFN-gamma, IL-4, and IL-17. Mice infected with H. pylori developed a mixed Th17/Th1 response; Th17 responses preceded Th1 responses. Treatment of mice with an anti-IL-17 Ab but not a control Ab significantly reduced the H. pylori burden and inflammation in the stomach. H. pylori colonization and gastric inflammation were also lower in IL-17(-/-) mice. Furthermore, administration of recombinant adenovirus encoding mouse IL-17 increased both H. pylori load and inflammation. Further analysis showed that the Th1 cell responses to H. pylori were downregulated when IL-17 is deficient. These results together suggest that H. pylori infection induces a mixed Th17/Th1 cell response and the Th17/IL-17 pathway modulates Th1 cell responses and contributes to pathology.

Psychological stress enhances the colonization of the stomach by Helicobacter pylori in the BALB/c mouse.

Helicobacter pylori infection is a risk factor for development of peptic ulcers, and psychological stress (PS) may have a role in the pathogenesis of this condition. However, no interaction between PS and H. pylori infection (HI) has been established in the development of peptic ulcer, because colonization by H. pylori is the first step in the infection of the gastric mucosa, we examined H. pylori colonization of the stomach in BALB/c mice after PS. The mice were subjected to PS in a communication box test, in which they observed other mice experiencing a physical stressor (electrical) before they were inoculated with H. pylori. We found that the H. pylori colonization in the stomach of psychologically stressed mice was significantly greater than in the control mice (P < 0.05), and histological examination showed that the gastric mucosal injury in the stressed mice was more extensive than in the control mice (P < 0.05). To explore the underlying mechanisms, we administered RU486 (a type II glucocorticoid (GC) receptor antagonist) to antagonize the effect of endogenous corticosterone: this treatment decreased colonization by H. pylori in the psychologically stressed mice. We conclude that HI of the stomach of BALB/c mice is enhanced by PS, and the effect may be mediated by GCs.

[Comparative proteomics analysis of Helicobacter pylori after adaptive colonization in Mongolian gerbils].

To study adaptive protein variation of H. pylori after colonization in Mongolian gerbils, Firstly, Clinical isolated strain M0 of H. pylori were inoculated into Mongolian gerbils and acclimated through serial passages in vivo for procuring an adaptive colonization H. pylori strain. Then, two-dimensional electrophoresis (2-DE) and mass spectrometry (MS) was taken to separate and identify the global proteins significantly changed between H. pylori strain M0 and the adaptive strain. Through serial passages the infectious rate increased from about 2/10 to 9/10 and a adaptive colonization strain M13 has been obtained. Comparative proteomic technology display that the proteinogram of H. pylori have changed after colonization in gerbils. Out of 5 differential protein spots cut out of gels for MALDI-TOF-MS identification, 4 spots were successfully identified, among which, Icd, RfaD and HP0318 were significantly higher in M13 compared with M0, while only HypB were found in M13. So far, HP0318 is a conserved hypothetical protein. These proteins may be important factors of H. pylori for adaptive colonization.