Shu-Chen Wei

Host-microbial interactions and regulation of intestinal epithelial barrier function: From physiology to pathology

The gastrointestinal tract is the largest reservoir of commensal bacteria in the human body, providing nutrients and space for the survival of microbes while concurrently operating mucosal barriers to confine the microbial population. The epithelial cells linked by tight junctions not only physically separate the microbiota from the lamina propria, but also secrete proinflammatory cytokines and reactive oxygen species in response to pathogen invasion and metabolic stress and serve as a sentinel to the underlying immune cells. Accumulating evidence indicates that commensal bacteria are involved in various physiological functions in the gut and microbial imbalances (dysbiosis) may cause pathology. Commensal bacteria are involved in the regulation of intestinal epithelial cell turnover, promotion of epithelial restitution and reorganization of tight junctions, all of which are pivotal for fortifying barrier function. Recent studies indicate that aberrant bacterial lipopolysaccharide-mediated signaling in gut mucosa may be involved in the pathogenesis of chronic inflammation and carcinogenesis. Our perception of enteric commensals has now changed from one of opportunistic pathogens to active participants in maintaining intestinal homeostasis. This review attempts to explain the dynamic interaction between the intestinal epithelium and commensal bacteria in disease and health status.

The Asia-Pacific consensus on ulcerative colitis

Inflammatory bowel disease (IBD) is increasing in many parts of the Asia‐Pacific region. There is a need to improve the awareness of IBD and develop diagnostic and management recommendations relevant to the region. This evidence‐based consensus focuses on the definition, epidemiology and management of ulcerative colitis (UC) in Asia.

Placenta growth factor expression is correlated with survival of patients with colorectal cancer

Background: Overexpression of vascular endothelial growth factor (VEGF) correlates with vascularity, metastasis, and proliferation in colorectal cancer but the role of its homologue, placenta growth factor (PlGF), is unknown. The aim of this study was to evaluate expression and clinical implications of PlGF in colorectal cancer. Methods: We investigated 74 tumour/non-tumour pairs of colorectal cryosections. Clinical staging was based on the UICC-TNM classification. Expression levels of mRNA for PlGF and VEGF were analysed with quantitative real time reverse transcription-polymerase chain reaction. Proteins were analysed by immunohistochemical staining and enzyme linked immunoabsorbant assay. Analysis of the differences in PlGF and VEGF levels between tumour and non-tumour tissues in the same patient were performed by paired t test; differences between localised and advanced disease patients by the Mann-Whitney, χ2, and Fisher’s exact tests and survival curves by the Kaplan-Meier method. Results: Expression levels for both growth factors were significantly higher in tumour than in non-tumour tissues (p⩽0.001). The ratio of PlGF expression in tumour to non-tumour in the advanced disease group was significantly higher than for the localised disease group (p = 0.009). Patients with more tumour PlGF mRNA had shorter survival (p = 0.028). The majority of PlGF was expressed in tumour cells. Conclusions: Our results suggest that PlGF expression correlates with disease progression and patient survival and may be used as a prognostic indicator for colorectal cancer.

Adiponectin as a potential differential marker to distinguish pancreatic cancer and chronic pancreatitis.

Serum adiponectin (ADP) levels are reported inversely related to the risk in breast, endometrial cancer, and gastric cancer. Serum ADP as a potential marker compared with CA-19-9 in pancreatic carcinoma (PC) and chronic pancreatitis (CP) was studied. Adiponectin and CA-19-9 levels were examined at the time of diagnosis in patients with CP and PC. Methods: Serum ADP and CA-19-9 levels were measured by immunoassays in 72 patients with PC and 39 with CP and 290 control subjects. Results: The median levels of ADP for PC were significantly higher than those for CP and control subjects (P = 0.0035). Increasing the upper reference value of ADP allowed for better discrimination between CP and PC. The introduction of 28 ng/mL as a cutoff for ADP significantly improved its specificity. At an elevated cutoff level for ADP (28 ng/mL), a better discrimination between PC and CP was obtained. Conclusions: Adiponectin might be useful in the differential diagnosis of PC and CP with elevated CA-19-9. This gives rise to the possibility that ADP has a potential role in differentiating CP and PC.

Notch signaling prevents mucous metaplasia in mouse conducting airways during postnatal development

Goblet cell metaplasia and mucus overproduction contribute to the pathogenesis of chronic lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). Notch signaling regulates cell fate decisions and is crucial in controlling goblet cell differentiation in the gut epithelium. Little is known, however, about how endogenous Notch signaling influences the goblet cell differentiation program that takes place in the postnatal lung. Using a combination of genetic and in vitro approaches here we provide evidence of a novel role for Notch in restricting goblet cell differentiation in the airway epithelium during the postnatal period. Conditional inactivation of the essential Notch pathway component Pofut1 (protein O-fucosyltransferase1) in Tgfb3-Cre-expressing mice resulted in an aberrant postnatal airway phenotype characterized by marked goblet cell metaplasia, decreased Clara cell number and increase in ciliated cells. The presence of the same phenotype in mice in which the Notch transcriptional effector Rbpjk was deleted indicated the involvement of the canonical Notch pathway. Lineage study in vivo suggested that goblet cells originated from a subpopulation of Clara cells largely present in proximal airways in which Notch was disrupted. The phenotype was confirmed by a panel of goblet cell markers, showed no changes in cell proliferation or altered expression of proinflammatory cytokines and was associated with significant downregulation of the bHLH transcriptional repressor Hes5. Luciferase reporter analysis suggested that Notch directly repressed MUC5AC transcription in lung epithelial cells. The data suggested that during postnatal life Notch is required to prevent Clara cells from differentiating into goblet cells.

Serum vascular endothelial growth factor/soluble vascular endothelial growth factor receptor 1 ratio is an independent prognostic marker in pancreatic cancer.

Objectives: Tumor angiogenesis is the consequence of an imbalance between positive and negative angiogenic regulatory factors. We sought to determine the role of pretreated serum angiogenic factors, including vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and soluble vascular endothelial growth factor receptor 1 (sVEGFR-1), in predicting clinical outcome in patients with pancreatic cancer. Methods: We assessed pretreated serum VEGF, PlGF, and sVEGFR-1 levels in 92 patients with pancreatic adenocarcinoma and 60 healthy control subjects using an enzyme-linked immunosorbent assay. The correlation between these angiogenesis-related factors and clinicopathologic factors, including staging and overall survival, was analyzed. Results: Serum levels of VEGF, PlGF, and sVEGFR-1 were significantly higher in patients with pancreatic cancer compared with those in controls (583.8 ± 559.5 vs 187.63 ± 393.32, 17.65 ± 7.34 vs 10.93 ± 1.21, and 50.94 ± 51.17 vs 15.55 ± 1.98 pg/mL, respectively; P < 0.0001). A reverse correlation was observed between sVEGFR-1 level and the advance of tumor stage. Cox regression analysis showed that the VEGF/sVEGFR-1 ratio was an independent predictor for pancreatic cancer survival. Higher VEGF/sVEGFR-1 ratio was significantly correlated with poor outcome in patents with pancreatic cancer. Conclusions: Vascular endothelial growth factor/sVEGF-1 ratio is an independent prognostic factor for survival in pancreatic cancer. Its significance should be assessed when considering antiangiogenic therapy in treating pancreatic cancer patients.

Excess Soluble fms-Like Tyrosine Kinase 1 and Low Platelet Counts in Premature Neonates of Preeclamptic Mothers

Objective. To investigate the relationship of neonatal platelet count and preeclampsia to levels of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) in the cord blood of preterm infants. Methods. Sixty-nine preterm infants with a gestational age between 26 and 37 weeks at birth were enrolled. sFlt-1, PlGF, and VEGF levels in the cord blood of preterm neonates, with or without maternal preeclampsia, were measured using a standardized sandwich enzyme-linked immunosorbent assay method. Results. Infants with maternal preeclampsia had higher cord blood sFlt-1 but lower PlGF and VEGF levels. There was a significantly positive relationship between neonatal platelet count and birth weight and a significantly negative relationship between neonatal platelet count and cord blood sFlt-1 levels. Multiple regression analysis revealed that only birth weight and cord blood sFlt-1 levels were independently related to neonatal platelet count, whereas maternal preeclampsia, gestational age (GA), and small for GA (SGA) were not related. Neonates with thrombocytopenia had higher cord blood sFlt-1 levels but lower birth weight. A significant correlation was also found between birth weight and cord blood sFlt-1 levels. Multiple regression with birth weight as the dependent variable found that only GA and cord blood sFlt-1 levels were independently related. Furthermore, infants with high cord blood sFlt-1 were more likely to have lower platelet count and maternal preeclampsia, be SGA, and have a trend toward lower birth weight. Conclusion. Excess sFlt-1 may play an important role in the development of maternal preeclampsia- induced neonatal thrombocytopenia, and SGA.

Soluble vascular endothelial growth factor receptor-1 protects mice in sepsis

Objective:To determine the putative role in the modulation of inflammation of a soluble form of Flt-1 (sFlt), a potent vascular endothelial growth factor antagonist, in experimental endotoxemia and sepsis. Design:Randomized prospective experimental study. Setting:University medical laboratory. Subjects:Male C56BL/6 strain mice. Interventions:We investigated the expression patterns and the effects of vascular endothelial growth factor and soluble Flt-1 in experimental endotoxic shock and sepsis. The possible anti-inflammatory mechanism of soluble Flt-1 was also evaluated. Measurements and Main Results:Both vascular endothelial growth factor and sFlt-1 were rapidly released from macrophages activated in vitro by lipopolysaccharide and in the plasma of endotoxemic mice. Administration of vascular endothelial growth factor enhanced proinflammatory cytokine production and mediated a dramatic increase in mortality in endotoxemic mice. Treatment with sFlt-1 attenuated inflammatory responses, inhibited recruitment of inflammatory cells into the peritoneal cavity, and improved survival in a lethal endotoxemia and cecal ligation and puncture-induced sepsis model, even when administered as late as 24 hrs after the onset of sepsis. Conclusions:These findings support a critical protective role of sFlt-1 in endotoxic shock and sepsis. sFlt-1 may therefore have utility as an adjunctive agent for the treatment of sepsis syndrome.

Lipopolysaccharide-induced Notch signaling activation through JNK-dependent pathway regulates inflammatory response.

BackgroundNotch and TLR pathways were found to act cooperatively to activate Notch target genes and to increase the production of TLR-induced cytokines in macrophages. However, the mechanism of LPS-induced Notch activation and its role in sepsis still remains unclear.MethodsWe analyzed the expression patterns of Notch components in a LPS-stimulated murine macrophage cell line using real-time PCR and western blotting. The role of DAPT, a gamma-secretase inhibitor that is known to be a potent Notch inhibitor, in LPS-induced cytokine release and experimental sepsis in mice was also explored. Students t-test was used to analyze the difference between the two groups.ResultsWe found that Notch signaling was activated after LPS stimulation. The expression of Jagged 1, a Notch ligand, induced by LPS occurred in a JNK-dependent manner. In addition, Notch target genes were upregulated by early Notch-independent activation followed by delayed Notch-dependent activation after LPS stimulation. Disruption of Notch signaling by DAPT attenuated the LPS-induced inflammatory responses, including vascular endothelial growth factor (VEGF) and high-mobility group box chromosomal protein 1 (HMGB1), both in vitro and in vivo and partially improved experimental sepsis survival.ConclusionsThese findings support the existence of a synergistic effect of Notch signaling and the LPS pathway both in vitro and in vivo. Therefore, in the future Notch inhibitors may be utilized as adjunctive agents for the treatment of sepsis syndrome.

Bile duct hamartomas : A report of two cases

Bile duct hamartomas (von Meyenburgs complexes) of the liver are usually detected at laparotomy or autopsy as an incidental finding, and usually they are multiple. We report two cases of proved bile duct hamartomas of the liver. The first was in a 65-year-old man whose initial sepsis and many hepatic lesions were interpreted as microabscess of the liver. The second patient was a 39-year-old man, a hepatitis B surface antigen carrier, in whom an incidental hepatic tumor was found. We suggest that liver biopsy be done in hepatic lesions with uncertain clinical features, because the histologic findings may change the treatment plan.