Shuaiyin Chen

Role of Helicobacter pylori infection in pathogenesis of gastric carcinoma

Gastric cancer (GC) is one of the most common carcinoma and the second leading cause of cancer-related deaths worldwide. Helicobacter pylori (H. pylori) infection causes a series of precancerous lesions like gastritis, atrophy, intestinal metaplasia and dysplasia, and is the strongest known risk factor for GC, as supported by epidemiological, preclinical and clinical studies. However, the mechanism of H. pylori developing gastric carcinoma has not been well defined. Among infected individuals, approximately 10% develop severe gastric lesions such as peptic ulcer disease, 1%-3% progresses to GC. The outcomes of H. pylori infection are determined by bacterial virulence, genetic polymorphism of hosts as well as environmental factors. It is important to gain further understanding of the pathogenesis of H. pylori infection for developing more effective treatments for this common but deadly malignancy. The recent findings on the bacterial virulence factors, effects of H. pylori on epithelial cells, genetic polymorphism of both the bacterium and its host, and the environmental factors for GC are discussed with focus on the role of H. pylori in gastric carcinogenesis in this review.

Helicobacter pylori cytotoxin-associated gene A protein upregulates α-enolase expression via Src/MEK/ERK pathway: Implication for progression of gastric cancer

Persistent infection with Helicobacter pylori confers an increased risk for the development of gastric cancer. In our previous investigations, we found that ENO1 was overexpression in cagA-positive H. pylori-infected gastric epithelial AGS cells by proteomic method, in contrast to the isogenic cagA knock out mutant H. pylori-infected cells. ENO1 is a newly identified oncoprotein overexpressed in some cancer. However, the relationship between H. pylori infection and ENO1 expression still remains undefined. The AGS gastric cancer cells were transfected with WT-cagA plasmid and PR-cagA plasmids. Expression of ENO1 mRNA and protein were measured by real-time quantitative PCR and western blot analysis. Signal protein inhibitor treatment was used to investigate the signal pathways. It was found that the ENO1 mRNA and protein overexpression levels were dependent on cagA gene expression and CagA protein phosphorylation. Further analysis revealed that the Src, MEK and ERK pathway was involved in this upregulation effect. Our data suggest that ENO1 was upregulated by CagA protein through activating the Src and MEK/ERK signal pathways, thereby providing a novel mechanism underlying H. pylori-mediated gastric diseases.

Involvement of inducible nitric oxide synthase and mitochondrial dysfunction in the pathogenesis of enterovirus 71 infection

Enterovirus71 (EV71) is recognized as the main causative agent of severe hand, foot and mouth disease (HFMD). However, the pathogenesis of EV71 infection has not been well characterized. Clinical evidence indicated that inducible nitric oxide synthase (iNOS) induction in the lung of HFMD patients contributes to the severe symptoms of pulmonary edema. In the present study, we recruited 142 subjects including HFMD patients and controls, and serum level of nitric oxide (NO) was determined. Next, cellular and animal model were used to further investigate the roles of iNOS and mitochondria damage during EV71 infection. Serum NO level in HFMD patients with mild or severe symptoms was higher than that in controls, and there was a trend towards an increase in the serum NO level of severe cases relative to mild cases. EV71 infection caused apoptosis and increased levels of NO, iNOS, superoxide dismutase (SOD) activity and malondialdehyde (MDA), and degraded mitochondrial membrane potential (ΔΨm) in vitro. Pathological alterations of mitochondrial morphology were observed in vitro and in vivo. Furthermore, the expression of iNOS levels in target organs including brain, spinal cord, skeletal muscle, lung and heart were increased with the progression of the pathogenesis of EV71 infection in mice. Taken together, iNOS and mitochondrial damage participate in the pathogenesis of EV71 infection.

Pulmonary edema following central nervous system lesions induced by a non- mouse-adapted EV71 strain in neonatal BALB/c mice

BackgroundEnterovirus (EV) infection has been a serious health issue in Asia-Pacific region. It has been indicated that the occurrence of fatal hand foot and mouth disease (HFMD) cases following EV71 infection is mainly attributed to pulmonary edema. However, the development of pulmonary disorders after EV71 infection remains largely unknown. To establish an EV71-infected animal model and further explore the underlying association of central nervous system (CNS) invasion with pulmonary edema, we isolated a clinical source EV71 strain (ZZ1350) from a severe case in Henan Province.MethodsWe evaluated the cytotoxicity of ZZ1350 strain and the susceptibility in 3-day-old BALB/c mice with intraperitoneal, intracerebral and intramuscular inoculation. Various histopathological and immunohistochemical techniques were applied to determine the target organs or tissue damage after infection. Correlation analysis was used to identify the relationship between CNS injury and pulmonary disorders.ResultsOur experimental results suggested that ZZ1350 (C4 subtype) had high cytotoxicity against African green monkey kidney (Vero) cells and human rhabdomyosarcoma (RD) cells and neonatal BALB/c mice were highly susceptible to the infection with ZZ1350 through three different inoculation routes (2 × 106 pfu/mouse) exhibiting severe neurological and respiratory symptoms that were similar to clinical observation. Viral replication was found in brain, spinal cord, skeletal muscle, lung, spleen, liver, heart of infected mice and these sections also showed histopathological changes. We found that brain histology score was positive correlated with lung histology score in total experimental mice and mice under the three inoculation routes (P < 0.05). At the same time, there were positive correlations between spinal cord score and lung score in total experimental mice and mice with intracerebral inoculation (P < 0.05).ConclusionsZZ1350 strain is effective to establish animal model of EV71 infection with severe neurological and respiratory symptoms. The development of pulmonary disorders after EV71 infection is associated with severity of CNS damage.

Production and delivery of Helicobacter pylori NapA in Lactococcus lactis and its protective efficacy and immune modulatory activity

Helicobacter pylori neutrophil-activating protein A subunit (NapA) has been identified as a virulence factor, a protective antigen and a potent immunomodulator. NapA shows unique application potentials for anti-H. pylori vaccines and treatment strategies of certain allergic diseases and carcinomas. However, appropriate production and utilization modes of NapA still remain uncertain to date. This work has established a novel efficient production and utilization mode of NapA by using L. lactis as an expression host and delivery vector, and demonstrated immune protective efficacy and immune modulatory activity of the engineered L. lactis by oral vaccination of mice. It was observed for the first time that H. pylori NapA promotes both polarized Th17 and Th1 responses, which may greatly affect the clinical application of NapA. This report offers a promising anti-H. pylori oral vaccine candidate and a potent mucosal immune modulatory agent. Meanwhile, it uncovers a way to produce and deliver the oral vaccine and immunomodulator by fermentation of food like milk, which might have striking effects on control of H. pylori infection, gastrointestinal cancers, and Th2 bias allergic diseases, including many food allergies.

Mast cells contribute to Enterovirus 71 infection-induced pulmonary edema in neonatal mice

Enterovirus (EV) 71 infection has been widely acknowledged as the leading cause of severe hand, foot and mouth disease (HFMD), which may rapidly lead to fatal pulmonary edema. In this study, we established a mouse model for EV71 infection exhibiting high incidence of severe symptoms with pulmonary edema. Mast cells (MCs) accumulation, activation and allergic inflammation were found in the brains, lungs and skeletal muscle of mice after EV71 infection, especially in the lungs of mice. Levels of histamine, platelet-activating factor (PAF), interleukin (IL)-4, IL-5, IL-13, tumor necrosis factor-α (TNF-α), nitric oxide (NO), endocrine gland-derived vascular endothelial growth factor (EG-VEGF) and noradrenaline (NA) were increased in EV71-infected lungs. In addition, EV71 infection reduced the number of pulmonary T cells, dendritic cells (DCs) and monocytes, and increased the number of lung eosinophils, Tregs and MCs. MCs number and tryptase expression in target organs or tissues posed a trend towards an increase from control to severe mice. There were positive correlations between MCs number in the brains (r = 0.701, P = 0.003), lungs (r = 0.802, P < 0.0001), skeletal muscles (r = 0.737, P = 0.001) and mean clinical score. Thus, our results suggested that MCs contributed to the pulmonary edema during EV71 infection.Enterovirus (EV) 71 can cause of severe hand, foot and mouth disease (HFMD), which may lead to fatal pulmonary edema. The authors determined that mast cells contribute to pulmonary edema during EV71 infection and that specific inhibitors of mast cell degranulation may be beneficial as therapy to treat EV71 infection-induced severe HFMD.

An engineered food-grade Lactococcus lactis strain for production and delivery of heat-labile enterotoxin B subunit to mucosal sites

BackgroundRecent researches have been focusing on mucosal immune adjuvants, which play the key roles in mucosal immunization and have become the limitation for non-injected vaccine development. Escherichia coli heat-labile enterotoxin B subunit (LTB) was regarded as a promising mucosal adjuvant for its nontoxicity and potent activity. LTB preparation issues have always been recurring, in part owing to that the recombinant LTB expressed by E. coli does not act as its native form.ResultsWe constructed an engineered Lactococcus lactis strain using a food-grade expression system. The LTB secreted by the engineered strain was detected in the culture supernatant, constituting 10.3% of the supernatant proteins, and recognized by mouse anti-LTB antibodies. The engineered strain, co-administered orally to SPF BALB/c mice with a H. pylori vaccine candidate expressing Lpp20 antigen, could significantly enhance the Lpp20-induced mucosal SIgA antibody responses against H. pylori.ConclusionsThis is the first report that LTB was efficiently produced and delivered via using a food-grade lactococcal expression system, which offers a novel production and utilization mode of this crucial mucosal adjuvant. The engineered L. lactis strain secreting LTB has considerable potential for oral vaccine formulation owing to its outstanding safety, adjuvant activity and high-level production.

Characterization of Critical Functions of Long Non-Coding RNAs and mRNAs in Rhabdomyosarcoma Cells and Mouse Skeletal Muscle Infected by Enterovirus 71 Using RNA-Seq

Enterovirus 71 (EV71) is the main pathogen of severe hand-foot-mouth disease (HFMD). Long non-coding RNAs (lncRNAs) are recognized as pivotal factors during the pathogenesis of viral infection. However, the critical functions of lncRNAs in EV71–host interactions have not been characterized. Here, for the first time, we performed global transcriptome analysis of lncRNA and mRNA expression profiles in EV71-infected human rhabdomyosarcoma (RD) cells and skeletal muscle of mice using second-generation sequencing. In our study, a total of 3801 novel lncRNAs were identified. In addition, 23 lncRNAs and 372 mRNAs exhibited remarkable differences in expression levels between infected and uninfected RD cells, while 104 lncRNAs and 2647 mRNAs were differentially expressed in infected skeletal muscle from neonatal mice. Comprehensive bioinformatics analysis included target gene prediction, lncRNA-mRNA co-expression network construction, as well as gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis mainly focused on differentially-expressed genes (DEGs). Our results suggest that lncRNAs may participate in EV71 infection-induced pathogenesis through regulating immune responses, protein binding, cellular component biogenesis and metabolism. The present study provides novel insights into the functions of lncRNAs and the possible pathogenic mechanism following EV71 infection.

Involvement of the renin-angiotensin system in the progression of severe hand-foot-and-mouth disease

Background Hand-foot-and-mouth disease (HFMD) is generally considered as a mild exanthematous disease to infants and young children worldwide. HFMD cases are usually mild and self-limiting but for few cases leads to complicated severe clinical outcomes, and even death. Previous studies have indicated that serum Ang II levels in patients with H7N9 infection were related to the severity of infection. However, the mechanisms underlying the pathogenesis of severe HFMD remain unclear. This study was undertaken to clarify the role of the renin-angiotensin system (RAS) in the progression of severe HFMD. Methods In the present study, 162 children including HFMD patients and healthy controls were recruited. The data was analyzed by time-series fashion. Concentrations of angiotensin II (Ang II) and noradrenaline (NA) in serum of patients were measured with ELISA. We established a mouse model for enterovirus 71 (EV71) infection and determined concentrations of Ang II, NA in tissue lysates at 3, 5 and 7 days post infection (dpi). Results The concentrations of Ang II and NA in serum of the HFMD patients with mild or severe symptoms were significantly higher than that in healthy controls. Additionally, the concentrations of Ang II and NA in serum of severe cases were significantly higher than those mild cases and the increased concentrations of Ang II and NA showed the same time trend during the progression of HFMD in the severe cases. Furthermore, the concentrations of Ang II and NA in target organs of EV71-infected mice including brains, skeletal muscle, and lungs were increased with the progression of EV71 infection in mice. Histopathological alterations were observed in the brains, skeletal muscle and lungs of EV71-infected mice. Conclusion Our study suggested that activation of the RAS is implicated in the pathogenesis of severe HFMD.

Molecular characteristics of antimicrobial resistance and virulence determinants of Staphylococcus aureus isolates derived from clinical infection and food

Staphylococcus aureus (S. aureus) is an important human etiologic agent. An investigation of the characteristics of common genotypes of S. aureus relating to pathogenicity and antibiotic resistance may provide a foundation to prevent infection.