Cholesterol depletion reduces entry of Campylobacter jejuni cytolethal distending toxin and attenuates intoxication of host cells.

Campylobacter jejuni is a common cause of pediatric diarrhea worldwide. Cytolethal distending toxin, produced by Campylobacter jejuni, is a putative virulence factor that induces cell cycle arrest and apoptosis in eukaryotic cells. Cellular cholesterol, a major component of lipid rafts, has a pivotal role in regulating signaling transduction and protein trafficking as well as pathogen internalization. In this study, we demonstrated that cell intoxication by Campylobacter jejuni cytolethal distending toxin is through the association of cytolethal distending toxin subunits and membrane cholesterol-rich microdomains. Cytolethal distending toxin subunits cofractionated with detergent-resistant membranes, while the distribution reduced upon the depletion of cholesterol, suggesting that cytolethal distending toxin subunits are associated with lipid rafts. The disruption of cholesterol using methyl-ß-cyclodextrin not only reduced the binding activity of cytolethal distending toxin subunits on the cell membrane but also impaired their delivery and attenuated toxin-induced cell cycle arrest. Accordingly, cell intoxication by cytolethal distending toxin was restored by cholesterol replenishment. These findings suggest that membrane cholesterol plays a critical role in the Campylobacter jejuni cytolethal distending toxin-induced pathogenesis of host cells.

Identification of 3',4',5'-trimethoxychalcone analogues as potent inhibitors of Helicobacter pylori-induced inflammation in human gastric epithelial cells.

Efforts to identify potent small molecule inhibitors of Helicobacter pylori led to the evaluation of 23 3',4',5'-trimethoxychalcone analogues. Some of the compounds displayed potent antibacterial activity against H. pylori. Three most active and selective compounds 1, 7, and 13 also showed the bactericide activity against the reference as well as multidrug-resistant strains of H. pylori. Additionally, the aforementioned three compounds potentially inhibited the H. pylori adhesion and invasion to human gastric epithelial (AGS) cells. Furthermore, these selective compounds inhibited the H. pylori-induced gastric inflammation by reduced inflammatory mediator's nuclear factor kappa B activation, and the secretion of interleukin-8.

Bioevaluation of Anisomeles indica extracts and their inhibitory effects on Helicobacter pylori-mediated inflammation.

ETHNOPHARMACOLOGICAL RELEVANCE: Helicobacter pylori is associated with the majority of gastric disorders and the antibiotic resistant rates have increased annually worldwide. Anisomeles indica and its constituent, ovatodiolide (OVT), were shown to have bactericide activity against Helicobacter pylori. The aim of this study was to manufacture extracts containing the effective constituent, OVT, and evaluate their bactericidal function and the inhibition of inflammatory responses to Helicobacter pylori infection. MATERIALS AND METHODS: Various concentrations of ethanol for extraction of Anisomeles indica were performed and the content of OVT was analyzed by high-performance liquid chromatography (HPLC). The anti-bacterial activity of Anisomeles indica ethanol extracts and the constituent OVT were determined. Additional experiments were performed to investigate the Anisomeles indica ethanol extracts and OVT to inhibit the Helicobacter pylori-induced inflammation of both gastric epithelial cells and macrophages. RESULTS: Amongst the extracts tested, 50% and 95% ethanol extracts contained large amount of OVT and showed potent anti-Helicobacter pylori activity. An in vitro Helicobacter pylori-infection model revealed that 95% ethanol extract attenuated Helicobacter pylori-induced nuclear factor kappa B (NF-κB) activity and interleukin (IL)-8 secretion of gastric epithelial cells. In addition, 95% ethanol extract significantly inhibited lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS), as well as production of nitric oxide (NO) and tumor necrosis factor α (TNF-α) by macrophages. CONCLUSIONS: This study reveals that Anisomeles indica ethanol extracts containing OVT may be a potent and economic therapeutic agent for Helicobacter pylori infection and attenuation of Helicobacter pylori-mediated inflammation.

Synthesis and bioevaluation of novel 3,4,5-trimethoxybenzylbenzimidazole derivatives that inhibit Helicobacter pylori-induced pathogenesis in human gastric epithelial cells.

Helicobacter pylori infection is associated with gastritis, peptic ulcer, and even gastric malignancy. H. pylori's antibiotic resistance is the major obstacle preventing its eradication. A series of 3,4,5-trimethoxybenzylbenzimidazole derivatives were synthesized and evaluated for their anti-H. pylori activity. The compound, 2-fluorophenyl-5-methyl-1-(3,4,5-trimethoxybenzyl)benzimidazole (FMTMB), was determined as the most potent in the inhibition of H. pylori growth and pathogenesis of host cells. An in vitro H. pylori infection model revealed that FMTMB inhibited H. pylori adhesion and invasion of gastric epithelial cells. Results from this study provide evidence that FMTMB is a potent therapeutic agent that exhibits both anti-H. pylori growth properties and anti-H. pylori-induced pathogenesis of cells.

Proteomics-based identification of haptoglobin as a novel plasma biomarker in oral squamous cell carcinoma.

BACKGROUND: Identification of tumor biomarkers to assist early diagnosis and monitoring of disease progression may potentially decrease the mortality and morbidity associated with oral cancer. METHODS: A mouse model with oral squamous cell carcinoma (OSCC) induced by 4-nitroquinoline 1-oxide (4-NQO)/arecoline in drinking water was established to discover stage-associated biomarkers. A proteomics approach, immunoblot and immunohistochemical analysis were used to validate the expressed biomarkers in mice with OSCC. Human plasma samples were also collected and candidate biomarkers were evaluated using enzyme-linked immunosorbent assay. RESULTS: Proteomic profiling of mouse plasma samples indicated that haptoglobin and apolipoprotein A1 precursor were up-regulated in the mice with OSCC. Immunoblotting of plasma samples and immunohistochemical analysis of oral tissues showed a significantly higher level of haptoglobin in the OSCC mice than in the control mice. The expression of haptoglobin in human plasma samples from 52 patients with OSCC indicated a strong correlation between the increasing levels of haptoglobin and the clinical stages of OSCC (P<0.01). CONCLUSIONS: These results suggest that haptoglobin has a great potential as a sensitive plasma biomarker for early detection of patients with OSCC.