Jung Mogg Kim

Helicobacter pylori induces an array of pro‐inflammatory cytokines in human gastric epithelial cells: Quantification of mRNA for interleukin‐8, ‐1α/β, granulocyte‐macrophage colony‐stimulating factor, monocyte chemoattractant protein‐1 and tumour necrosis factor‐α

Despite the fact that Helicobacter pylori is known to be non‐invasive, mucosal infiltration of inflammatory cells have been observed in the gastric mucosa. The exact pathogenesis of such an inflammatory reaction has not been well defined. We explored the repertoire of cytokine genes expressed in human gastric epithelial cells in response to coculture with H. pylori. After gastric epithelial cells, SNU‐5 and KATO III, were infected with H. pylori, expression of several cytokine genes was assessed using quantitative reverse transcription polymerase chain reaction. Interleukin (IL)‐8, ‐1α and ‐1β mRNA were expressed in both gastric epithelial cells throughout the entire infection period. In SNU‐5, IL‐1α and IL‐8 mRNA were expressed at 1 h, reached a peak level at 4 h and then decreased. Interleukin‐1β mRNA was expressed less frequently than IL‐1α or IL‐8 mRNA. In SNU‐5 cells, granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), monocyte chemoattractant protein‐1 (MCP‐1), and tumour necrosis factor‐α (TNF‐α) mRNA were expressed at 9h, but was not expressed in KATO III. Gene expression paralleled the amount of IL‐8 protein measured by enzyme‐linked immunoabsorbent assay (ELISA). Interleukin‐8 mRNA expression was not observed in KATO III cells infected with Campylobacter fetus ssp. fetus, Campylobacter jejuni or Escherichia coli. IL‐8 mRNA expression was increased not only in gastric epithelial cells but also in non‐gastric cells infected with H. pylori. These results suggest that an inflammatory reaction induced by H. pylori may be initially triggered by an array of pro‐inflammatery cytokines expressed by infected gastric epithelial cells.

Distribution of Antibiotic MICs for Helicobacter pylori Strains over a 16-Year Period in Patients from Seoul, South Korea

ABSTRACT Recently, the development of antibiotic resistance emerged as a significant clinical problem in the eradication of Helicobacter pylori. We investigated the MICs of antibiotics for 135 H. pylori isolates from adults in Seoul, South Korea, over the past 16 years. The MICs of amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, and ciprofloxacin increased from 1987 to 2003. Rates of primary resistance to clarithromycin increased from 2.8% in 1994 to 13.8% in 2003. The A2144G mutation was frequently observed in the 23S rRNA gene in clarithromycin-resistant isolates. The increase in resistance to clarithromycin seems to result in a decrease in eradication efficacy for H. pylori. These results suggest that the MICs of several antibiotics for H. pylori have increased over the past 16 years in Seoul.

Prevalence of Primary and Secondary Antimicrobial Resistance of Helicobacter pylori in Korea from 2003 through 2012

Antimicrobial resistance of Helicobacter pylori (H. pylori) affects the efficacy of eradication therapy. The aim of this study was to estimate the prevalence of primary and secondary resistance of H. pylori isolates to antibiotics and to characterize the risk factors associated with antimicrobial resistance in Korea.

Simvastatin induces apoptosis in human colon cancer cells and in tumor xenografts, and attenuates colitis‐associated colon cancer in mice

Statins, HMG‐CoA reductase inhibitors could be associated with the risk reduction of colorectal cancer. We previously demonstrated that simvastatin inhibits NF‐κB signaling in human intestinal epithelial cells and ameliorates acute murine colitis. The aim of our study was to evaluate the effects of simvastatin on the apoptotic pathways related to NF‐κB signaling in colon cancer cells, and on anticancer effects in 2 different animal models. We treated cell lines (COLO 205 and HCT 116) with simvastatin or vehicle and determined apoptosis by cell cycle analysis, Annexin V‐FITC staining, caspase‐3 activity assay and confocal microscopy. We assessed the expression of antiapoptotic factors by RT‐PCR and Western blotting. In the colitis‐associated colon cancer (CAC) model, we induced colonic tumors in C57/BL6 mice by azoxymethane and dextran sulfate sodium administration, and evaluated simvastatins effect on tumor growth. In the xenograft model, we evaluated its effect on the inoculated tumor growth. In both cell lines, simvastatin caused dose‐ and time‐dependent cell death. Annexin V staining significantly increased after simvastatin treatment. It augmented caspase‐3 activity and downregulated the expression of Bcl‐2, Bcl‐xL, cIAP1 and cFLIP. In the CAC model, simvastatin significantly reduced tumor development. In the xenograft model, tumors from animals treated with simvastatin had smaller volumes, larger necrotic areas, lower expression of VEGF and higher apoptotic scores. In conclusion, simvastatin inhibited colon cancer development by induction of apoptosis and suppression of angiogenesis. These results suggest that simvastatin could be a potential chemopreventive and therapeutic agent of CAC as well as de novo colon cancer.

Plant sterol guggulsterone inhibits nuclear factor-κB signaling in intestinal epithelial cells by blocking IκB kinase and ameliorates acute murine colitis

Background/Aims The plant sterol guggulsterone has been shown to have anti‐inflammatory properties. It remains unknown, however, whether guggulsterone is effective for the treatment of inflammatory bowel disease (IBD). Therefore, we investigated anti‐inflammatory effects of guggulsterone on intestinal epithelial cells (IEC) and on experimental murine colitis models and elucidated its molecular mechanisms. Methods Human Caco‐2 cells and rat non‐transformed IEC‐18 cells were stimulated with interleukin (IL)‐1&bgr; or lipopolysaccharide (LPS) with or without guggulsterone. The effects of guggulsterone on nuclear factor (NF)‐&kgr;B signaling in IEC were examined by intercellular adhesion molecule (ICAM)‐1 real‐time reverse‐transcription polymerase chain reaction, NF‐&kgr;B transcriptional activity assay, Western blotting for I&kgr;B phosphorylation/degradation, electrophoretic mobility shift assay, and in vitro I&kgr;B kinase (IKK) assay. For in vivo study, dextran sulfate sodium (DSS)‐treated mice were fed with or without guggulsterone. Colitis was quantified by disease activity index and evaluation of macroscopic and microscopic findings. Phosphorylation of I&kgr;B and IKK in colon mucosa was assessed by Western blotting and immunohistochemistry. Results Guggulsterone significantly inhibited LPS‐ or IL‐1&bgr;‐induced ICAM‐1 gene expression, NF‐&kgr;B transcriptional activity, I&kgr;B phosphorylation/degradation, and NF‐&kgr;B DNA binding activity in IEC. Moreover, guggulsterone strongly blocked IKK activity. Administration of guggulsterone significantly reduced the severity of DSS‐induced murine colitis as assessed by clinical disease activity score, colon length, and histology. Furthermore, tissue upregulation of I&kgr;B and IKK phosphorylation induced by DSS was attenuated in guggulsterone‐treated mice. Conclusion Guggulsterone blocks NF‐&kgr;B signaling pathway by targeting IKK complex in IEC and attenuates DSS‐induced acute murine colitis, which suggests that guggulsterone could be an attractive therapeutic option in the treatment of IBD.

Institutional difference of antibiotic resistance of Helicobacter pylori strains in Korea

Goals This study was performed to evaluate whether the prevalence rates of primary antibiotic resistance in Helicobacter pylori isolates could be different between 2 institutions, which are located in the different areas in Korea, and to evaluate the effect of antibiotic resistance on the eradication rate of H. pylori. Study H. pylori were isolated from gastric mucosal biopsy specimens obtained from 113 Koreans, who did not have any eradication history. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, and moxifloxacin were examined according to the agar dilution method by 1 technician. Results All of these patients were treated with the same regimen, proton pump inhibitor-amoxicillin-clarithromycin triple therapy. There was a statistical difference in resistance to metronidazole, levofloxacin, and moxifloxacin among 6 antibiotics between 2 institutions located in Seoul and Gyeonggi province. The rates of eradication were 94.2% for the clarithromycin and amoxicillin-susceptible strains, and 42.8% for the amoxicillin-susceptible and clarithromycin-resistant strains. In contrast, eradication rate was 100% for the amoxicillin-resistant strains. Conclusions These results show that there is institutional difference of antibiotic resistance of H. pylori, explaining the institutional difference of eradication rate of H. pylori. The resistance to clarithromycin seems to be an important determinant for the eradication by proton pump inhibitor triple therapy but resistance to amoxicillin does not have any effect.

A positive feedback loop of IL-21 signaling provoked by homeostatic CD4+CD25- T cell expansion is essential for the development of arthritis in autoimmune K/BxN mice.

Rheumatoid arthritis is a joint-specific autoimmune inflammatory disease of unknown etiology. The K/BxN mouse is a model of rheumatoid arthritis that is thought to be mainly due to autoantibody-mediated inflammatory responses. We showed previously that homeostatic proliferation of autoreactive CD4+ T cells is required for disease initiation in the K/BxN mice. In this study, we show that the homeostatically proliferating CD4+CD25− T cells produce IL-21. We generated IL-21R-deficient (IL-21R−/−) K/BxN mice and found that these mice were completely refractory to the development of spontaneous arthritis. They contained fewer CD4+ T cells with a reduced proportion of homeostatically proliferating cells, fewer follicular Th cells, and, surprisingly, more Th17 cells than their control counterparts. They also failed to develop IgG1+ memory B cells and autoantigen-specific IgG1 Ab-secreting cells. IL-21 induced expression of receptor activator of NF-κB ligand (RANKL) a regulator of osteoclastogenesis, and few RANKL-expressing infiltrates were found in the synovia of IL-21R−/− K/BxN mice. Thus, our results demonstrate that IL-21 forms a positive feedback autocrine loop involving homeostatically activated CD4+ cells and that it plays an essential role in the development of autoimmune arthritis by mechanisms dependent on follicular Th cell development, autoreactive B cell maturation, and RANKL induction but independent of Th17 cell function. Consistent with this, in vivo administration of soluble the IL-21R-Fc fusion protein delayed the onset and progression of arthritis. Our findings suggest that effective targeting of IL-21-mediated processes may be useful in treating autoimmune arthritis.

Anti-inflammatory mechanism of metformin and its effects in intestinal inflammation and colitis-associated colon cancer.

The aim of this study is to evaluate the effect of metformin on intestinal inflammation.

Nasal absorption and biodistribution of plasmid DNA: an alternative route of DNA vaccine delivery

Nasal administration is emerging as a new route of DNA vaccine delivery. We aimed to study the extent of absorption and biodistribution of intranasally administered plasmid DNA. After intranasal administration, the level of plasmid DNA in the serum peaked at 1.5 h. The ratio of the area under the concentration (AUC) after intranasal administration of DNA over the AUC after intravenous administration was 0.14. At 15 min post inoculation, the highest organ distribution was observed in the liver and the cervical lymph nodes showed the highest level among the lymph nodes. At 24 h a higher localization of plasmids to the brain than to the lung and spleen was notable. A significant level of mRNA expression was observed in the lymph nodes. These results suggest that plasmid DNA can be substantially absorbed and distributed to the lymph nodes after intranasal administration, partly explaining the systemic immunogenicity of intranasally administered plasmid DNA vaccines.

Mitogen-activated protein kinase and activator protein-1 dependent signals are essential for Bacteroides fragilis enterotoxin-induced enteritis.

The approximately 20‐kDa heat‐labile toxin produced by enterotoxigenic Bacteroides fragilis is known to be associated with the development of enteritis. However, the molecular mechanism involved is not yet fully understood. In this study, we assessed whether B. fragilis enterotoxin (BFT)‐induced enteritis is related to mitogen‐activated protein kinase (MAPK) signaling pathways. In human colon epithelial cells, BFT activated three major MAPK cascades. The activation of p38 was sustained for a relatively long period, while the stimulation of extracellular signal‐regulated kinases (ERK) and c‐Jun N‐terminal kinase (JNK) was transient. BFT stimulation also activated AP‐1 signals composed of c‐Jun/c‐Fos heterodimers. The p38 inhibitor SB203580 and the ERK inhibitor U0126 reduced not only AP‐1 activity, but also decreased IL‐8 and MCP‐1 expression. In addition, the overexpression of superrepressors for c‐Jun and Ras induced by BFT stimulation decreased the levels of IL‐8 and MCP‐1 production. Furthermore, SB203580 prevented BFT‐induced colitis in the mouse ileum, as evidenced by significant decreases in villous destruction, neutrophil infiltration, and mucosal congestion. These results suggest that a pathway, including Ras, MAPK, and subsequent AP‐1 activation, is required for IL‐8 and MCP‐1 expression in intestinal epithelial cells exposed to BFT, and can be involved in the development of enteritis.