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PubMed2004

Agonist-induced polarized trafficking and surface expression of the adenosine 2b receptor in intestinal epithelial cells: role of SNARE proteins.

Adenosine, acting through the A2b receptor, induces vectorial chloride and IL-6 secretion in intestinal epithelia and may play an important role in intestinal inflammation. We have previously shown that apical or basolateral adenosine receptor stimulation results in the recruitment of the A2b receptor to the plasma membrane. In this study, we examined domain specificity of recruitment and the role of soluble N-ethylmaleimide (NEM) attachment receptor (SNARE) proteins in the agonist-mediated recruitment of the A2b receptor to the membrane. The colonic epithelial cell line T84 was used because it only expresses the A2b-subtype adenosine receptor. Cell fractionation, biotinylation, and electron microscopic studies showed that the A2b receptor is intracellular at rest and that apical or basolateral adenosine stimulation resulted in the recruitment of the receptor to the apical membrane. Upon agonist stimulation, the A2b receptor is enriched in the vesicle fraction containing vesicle-associated membrane protein (VAMP)-2. Furthermore, in cells stimulated with apical or basolateral adenosine, we demonstrate a complex consisting of VAMP-2, soluble NEM-sensitive factor attachment protein (SNAP)-23, and A2b receptor that is coimmunoprecipitated in cells stimulated with adenosine within 5 min and is no longer detected within 15 min. Inhibition of trafficking with NEM or nocodazole inhibits cAMP synthesis induced by apical or basolateral adenosine by 98 and 90%, respectively. cAMP synthesis induced by foskolin was not affected, suggesting that generalized signaling is not affected under these conditions. Collectively, our data suggest that 1) the A2b receptor is intracellular at rest; 2) apical or basolateral agonist stimulation induces recruitment of the A2b receptor to the apical membrane; 3) the SNARE proteins, VAMP-2 and SNAP-23, participate in the recruitment of the A2b receptor; and 4) the SNARE-mediated recruitment of the A2b receptor may be required for its signaling.

Adenosine↗
PubMed2005

Influence of intestinal bacteria on induction of regulatory T cells: lessons from a transfer model of colitis.

BACKGROUND: The resident flora plays a critical role in initiation and perpetuation of intestinal inflammation, as demonstrated in experimental models of colitis where animals fail to develop disease under germ free conditions. However, the importance of exposure to commensal bacteria before the onset of colitis is unclear. Our aim was to investigate the influence of previous exposure of donor animals to bacterial antigens on colitis development using a transfer model. METHODS: Clinical course and histology were evaluated after transfer of CD4(+)CD62L(+) lymphocytes from germ free and conventionally housed donor mice into SCID recipients. Cotransfer of CD4(+)CD62L(+) cells with CD4(+)CD62L(- )lymphocytes from both groups of mice was initiated. Lymphocytes were analysed by FACS, polarisation potential of cells determined, and cytokines measured within the supernatant by enzyme linked immunosorbent assay. RESULTS: Animals that received cells from germ free donors developed an earlier onset of colitis compared with mice reconstituted with lymphocytes from conventionally housed animals. Additionally, CD4(+)CD62L(- )cells from germ free mice were not able to abrogate colitis induced by cotransfer with CD4(+)CD62L(+) lymphocytes whereas CD4(+)CD62L(- )T cells from normal mice ameliorated disease. The higher percentage of CD4(+)GITR(+) expressing lymphocytes and the production of interleukin 10 after priming by dendritic cells suggests the presence of T(reg) cells within the CD4(+)CD62L(+) lymphocyte subset derived from conventional housed mice and assumes a lack of T(reg) cells within germ free mice. CONCLUSION: The results indicate that bacterial antigens are crucial for the generation and/or expansion of T(reg) cells in a healthy individual. Therefore, bacterial colonisation is of great importance in maintaining the immunological balance.

Adoptive Transfer↗
PubMed2004

CCR2 expressing CD4+ T lymphocytes are preferentially recruited to the ileum in Crohn's disease.

BACKGROUND AND AIMS: Chemokine receptors are key determinants of leucocyte trafficking. While the chemokine receptor CCR9 and its chemokine ligand CCL25 (TECK) mediate lymphocyte homing to the healthy small intestine, the chemokine receptors important for recruitment during intestinal inflammation are undefined. Animal studies have suggested potential roles for CCR2 and CCR5 in inflammatory bowel disease (IBD). The aim of this study was to understand the role of CCR2 in human IBD. METHODS: Resections of ileum or colon were obtained from patients undergoing surgery for small bowel Crohn's disease (SBCD; n = 10), Crohn's colitis (n = 5), ulcerative colitis (n = 6), and non-IBD related conditions (control ileum n = 11; control colon n = 11). Expression of CCR2 by lamina propria lymphocytes (LPLs) was determined by both flow cytometry and immunohistochemistry. As a functional correlate, chemotaxis assays using the CCR2 ligand, CCL2 (MCP-1), were performed. Expression of CCR2 by peripheral blood lymphocytes was determined by flow cytometry. RESULTS: There were greater than 30-fold more CCR2(+) LPLs in SBCD than in control ileum (29.3% (19.9-55.1) v 0.9% (0.4-11.5); p = 0.0007). Specifically, CCR2(+)CD4(+) LPLs were increased (p = 0.002) whereas CCR2(+)CD8(+) LPLs were not. Increased expression included both memory (CD45RO(+); p = 0.005) and naïve (CD45RO(-); p = 0.01) CCR2(+) populations. The increase in CCR2(+) LPLs in SBCD was confirmed by both immunohistochemistry (p = 0.0002) and enhanced chemotactic responses to CCL2. CCR2 expression was not increased in the peripheral blood of patients with SBCD, suggesting ongoing recruitment of the CCR2(+) population to the ileum. In contrast with SBCD, there was no significant increase in CCR2(+) LPLs in Crohn's colitis or ulcerative colitis samples. CONCLUSIONS: The chemokine receptor CCR2 appears to be an important contributor to accumulation of CD4(+) T lymphocytes in the ileum in small bowel Crohn's disease. Blockade of CCR2 may provide a novel therapeutic alternative.

Adult↗
PubMed2006

Inflammatory bowel disease in Thai children: presentations and outcomes of treatment.

Inflammatory bowel disease (IBD) is characterized by idiopathic chronic intestinal inflammation, due to abnormalities in gastrointestinal immunoregulation. Pediatric IBD has been rarely reported in Thailand. We describe eight children, five girls and three boys, who were diagnosed with IBD at Ramathibodi Hospital during 1999-2005 and had a follow-up of more than one year. Four cases had Crohn's disease (CD) and four cases had ulcerative colitis (UC). The ages at diagnosis ranged from 3.5 to 15.5 years. Diagnosis of IBD was delayed for more than 12 months in five patients. Five out of eight patients had early onset of disease, before 6 years of age. The manifestations included chronic diarrhea, abdominal pain, rectal bleeding and perianal lesions. The common extraintestinal manifestations were oral ulcer, anemia, weight loss and failure to thrive. Most patients had moderate to severe diseases and ileocolic fistula developed in one patient with CD. The disease was controlled with 5-aminosalicylic acid and corticosteroid in most patients. Four patients required additional therapy with azathioprine. Infliximab was used in two patients who were chronically steroid-dependent CD, one also had persistent ileocolic fistula and both patients responded well. During the follow-up period ranging from 1.1 to 5.8 years, three patients remained growth retardation; all had early onset of disease before 6 years of age, long duration of symptoms of more than 3 years before diagnosis and had multiple relapses. It is concluded that there is an increasing number of IBD in Thai children during the recent years. Most patients had moderate to severe diseases. Early onset of disease, delay in diagnosis and treatment are responsible for more complications, particularly persistent growth impairment. Early recognition of IBD and treatment are essential for a satisfactory long-term outcome.

Adolescent↗
PubMed2002

Responsiveness of intestinal epithelial cell lines to lipopolysaccharide is correlated with Toll-like receptor 4 but not Toll-like receptor 2 or CD14 expression.

BACKGROUND AND AIMS: Luminal bacteria have been implicated in the pathogenesis of inflammatory bowel diseases. Exposure of intestinal epithelial cells (IEC) to bacterial components potentially initiates intestinal inflammation by release of chemokines and recruitment of inflammatory cells. We analyzed receptor expression and signaling pathways involved in activation of human primary IEC and carcinoma-derived cell lines by lipopolysaccharide (LPS). MATERIALS AND METHODS: HT-29/p, HT-29/MTX, and Caco-2 cells were stimulated by LPS. IL-8 content in supernatants was analyzed by ELISA, and expression of CD14, Toll-like receptor (TLR) 2 and TLR 4 was determined by RT-PCR. Presence of TLR 4 protein was assessed by western blot analysis. LPS response was modulated by sCD14, LPS-binding protein, neutralization of CD14, and inhibitors of early signal activation. RESULTS: LPS dose-dependently induced secretion of IL-8 in undifferentiated HT-29/p cells while Caco-2 and permanently differentiated HT-29/MTX cells were unresponsive. Differently to HT-29/MTX, both HT-29/p and Caco-2 cells constitutively expressed transcripts for CD14. However, CD14 was not required for LPS-mediated induction of IL-8 in HT-29/p cells since neutralizing anti-CD14 antibodies left IL-8 levels unchanged. Unresponsiveness of Caco-2 and HT-29/MTX cells to LPS persisted in the presence of sCD14 and/or LPS-binding protein. Neither cell line expressed TLR 2 transcripts while only responsive HT-29/p cells expressed TLR 4 mRNA and TLR 4 protein. Butyrate down-regulated TLR 4 expression and significantly diminished LPS-dependent IL-8 secretion. Inhibition of G protein dependent kinase activation reduced IL-8 levels to 50%; the phosphatidyl-inositol-3'-kinase inhibitor LY294002 abrogated the response. CONCLUSION: Responsiveness of IEC lines to LPS is positively correlated with TLR 4 expression. Strategies targeting TLR 4 expression or TLR 4 mediated signaling may antagonize IEC activation by LPS.

Cross Reactions↗
PubMed1998

Response of human intestinal lamina propria T lymphocytes to interleukin 12: additive effects of interleukin 15 and 7.

BACKGROUND/AIM: Interleukin (IL) 12 is involved in the mucosal response during intestinal inflammation but its role is not fully understood. The response of human lamina propria T lymphocytes (T-LPL) to IL-12 in terms of interferon gamma (IFN-gamma) release and proliferation was investigated, exploring whether IL-15 and IL-7 cooperate with IL-12. The role of accessory molecules (CD2 and CD28) was also investigated. METHODS: Unstimulated and phytohaemagglutinin preactivated T-LPL cultures were incubated with or without the initial addition of cytokines, anti-CD2 or anti-CD28 antibodies. IFN-gamma mRNA was detected by reverse transcriptase polymerase chain reaction, and protein secretion was measured by enzyme linked immunosorbent assay (ELISA). RESULTS: IFN-gamma mRNA was induced in T-LPLs by IL-12 and IL-15 but not IL-7, whereas IFN-gamma was measured only in IL-12 stimulated T-LPL cultures. IL-12 induced IFN-gamma release was not abrogated by neutralising anti-IL-2 antibody or by cyclosporin A. IL-12 synergised with either anti-CD2 or anti-CD28 antibodies in inducing IFN-gamma synthesis. In preactivated T-LPLs, IL-7 enhanced IFN-gamma release induced by both IL-12 and anti-CD2, whereas IL-15 potentiated only IL-12 induced IFN-gamma synthesis. IL-12 did not induce proliferation of either unstimulated or preactivated T-LPLs and it did not enhance the CD2/CD28 stimulated T-LPL proliferative response. No transcript for IL-12 receptor beta1 subunit was detected in freshly isolated and activated T-LPLs whereas the beta2 subunit mRNA was consistently found in T-LPL samples. CONCLUSIONS: IL-12 induces human T-LPLs to produce and release IFN-gamma, and IL-15 and IL-7 cooperate with IL-12 in expanding the IFN-gamma mucosal response.

CD2 Antigens↗
PubMedDate not supplied

The role of plasma high molecular weight kininogen in experimental intestinal and systemic inflammation.

Inflammation is accompanied by activation of the plasma kallikrein-kinin system (KKS). KKS activation has been demonstrated in a variety of inflammatory human diseases. To further explore the participation of KKS in arthritis and inflammatory bowel disease, we used two experimental animal models in arthritis and enterocolitis. We found that activation of KKS is associated with arthritis induced by intraperitoneal injection of peptidoglycan-polysaccharide polymers (PG-PS) as well as the enterocolitis and systemic inflammation induced also by PG-PS when injected into the intestinal wall of genetically susceptible Lewis rats. We postulated that KKS participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion, and release of proteases. We demonstrated that therapy with a specific plasma kallikrein inhibitor modulated the experimental enterocolitis, arthritis, and systemic inflammation. The fact that deficiency of plasma high molecular weight kininogen in the genetically susceptible Lewis rat results in decreased chronic enterocolitis and systemic inflammation also supports our hypothesis. We suggest that KKS plays a similar role in idiopathic human intestinal inflammatory disease and arthritis, making kallikrein-kinin system proteins appealing targets for drug therapy in chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease.

Amino Acid Sequence↗
PubMed1999

C-X-C and C-C chemokine expression and secretion by the human colonic epithelial cell line, HT-29: differential effect of T lymphocyte-derived cytokines.

Differential chemokine production by colonic epithelial cells is thought to contribute to the characteristic increased infiltration of selected population of leukocytes cells in inflammatory bowel disease. We have previously demonstrated that IL-13 enhances IL-1alpha-induced IL-8 secretion by the colonic epithelial cell line HT-29. We have now explored the C-C chemokine expression and modulation in this system. The combination of TNF-alpha and IFN-gamma was the minimal stimulation required for regulated on activation, normal T cell expressed and secreted (RANTES) and monocyte chemoattractant protein (MCP-1) mRNA expression and secretion by HT-29 cells. The same stimulation induced a stronger IL-8 mRNA expression and secretion. Pretreatment with IL-13 or IL-4, reduced significantly the RANTES, and MCP-1, but not IL-8 mRNA expression and secretion. In contrast, IL-10 had no effect on either MCP-1, or RANTES, or IL-8 generation. Pretreatment of HT-29 cells with wortmannin suggested that the IL-13-induced inhibition of C-C chemokine expression is via activation of a wortmannin-sensitive phosphatidylinositol 3-kinase. These data demonstrate that colonic epithelial cell chemokine production can be differentially regulated by T cell-derived cytokines and suggest an interplay between epithelial cells and T lymphocytes potentially important in the intestinal inflammation.

Cell Communication↗
PubMed2000

Hapten-induced colitis associated with maintained Th1 and inflammatory responses in IFN-gamma receptor-deficient mice.

IFN-gamma is a potent pro-inflammatory cytokine thought to be involved in the pathogenesis of Crohn's disease. To further define the role of IFN-gamma in intestinal inflammation, we studied the effects of intra-colonic 2,4,6-trinitrobenzene sulfonic acid (TNBS) instillation in mice with a functionally inactivated IFN-gamma receptor 1 (IFN-gammaR1(- / -)). Our results indicate that IFN-gamma is not necessary for the induction of hapten-induced colitis: after TNBS administration both wild-type and IFN-gammaR1(- / -) mice lost body weight, and the histological features of TNBS-induced colitis were comparable. Colons of IFN-gammaR1(- / -) mice contained a greater number of cells, represented by macrophages and CD4(+) T cells; caudal lymph node cells produced more IFN-gamma and TNF-alpha upon stimulation in vitro. Moreover, IL-18 and IL-12 p40 RNA levels were comparably up-regulated after TNBS treatment in IFN-gammaR1(- / -) wild-type mice. These findings demonstrate that IFN-gamma is dispensable for the development of TNBS-induced colitis. Importantly, the production of Th1 cytokines (e. g. IFN-gamma and TNF-alpha) by caudal lymph node T lymphocytes was enhanced rather than decreased in IFNgammaR1(- / -) mice with no evidence for default Th2 development.

Animals↗
PubMed2003

Association between mutations in the CARD15 (NOD2) gene and Crohn's disease in Israeli Jewish patients.

Ulcerative colitis (UC) and Crohn's disease (CD) are heterogeneous disorders characterized by chronic intestinal inflammation. Genetic predisposition is a major risk factor in both diseases. The CARD15 (NOD2) gene has been implied as a candidate gene in the pathogenesis CD. Our aim was to delineate the frequency of three missense and one frameshift variant of CARD15 in Israeli Jewish CD and UC patients. DNA was extracted from blood samples from 238 unrelated inflammatory bowel disease (IBD) patients, 68 with UC and 170 with CD. The DNA was genotyped for two missense mutations, R675W and G881R, and one frameshift mutation, 980FS981X. Mutations in CARD15 were observed with significantly greater frequency in CD patients (46/170, 27%) than in UC patients (7/68, 10%) (P = 0.005). Homozygous and compound heterozygous carriers were restricted to seven (4%) patients with CD as compared to none of the UC patients (P = 0.01). Similar rates in Ashkenazi and non-Ashkenazi Jewish patients were observed. Age-of-onset of disease was lower in Ashkenazi mutation carriers as compared to non-carriers of Ashkenazi origin (18.7 +/- 8.6 years vs. 25.8 +/- 13.4 years, respectively, P = 0.03). No other phenotypic characteristics could distinguish mutation carriers from non-carriers. We conclude that germline mutations in the CARD15 gene are more frequently found in CD than UC patients and appear to predict an earlier age-of-onset in Ashkenazi Jewish patients. No association could be demonstrated between CARD15 mutations and specific disease course or behavior.

Adult↗
PubMed1979

Cerebral and retinal vascular complications of inflammatory bowel disease.

Recurrent retinal branch artery occlusions, carotid thromboembolism, cerebral venous thrombosis, transient brainstem ischemia, and massive brainstem and cerebral infarction complicated the course of inflammatory bowel disease in 5 patients. Three patients had ulcerative colitis and 2 had regional enteritis. The usual risk factors for stroke were absent. Neuropathological examination in 1 patient showed in situ thrombosis of small cerebral and brainstem arteries and veins. Coagulation studies showed thrombocytosis, short partial thromboplastin times, and elevation of fibrinogen and Factor VIII levels. Platelet counts and coagulation factors returned toward normal after control of intestinal inflammation in each of the 4 surviving patients. Inflammatory bowel disease can be accompanied by a hypercoagulable state that predisposes to stroke.

Adult↗
PubMed2005

High performance liquid chromatography analysis of MESNA (2-mercaptoethane sulfonate) in biological samples using fluorescence detection.

MESNA is the sodium salt of 2-mercaptoethane sulfonate, a thiol-containing drug. It is an antioxidant used particularly in renal protection. Several studies have proved that MESNA has beneficial effects in ischemic acute renal failure where it scavenges reactive oxygen species (ROS), due to the presence of the thiol group. It also reduces the size of urinary bladder cancer. MESNA was proved to be effective in preventing hemorrhagic cystitis induced by high doses of several chemotherapeutic regimens such as cyclophosphamide and ifosfamide. It has been shown that MESNA functions as an uroprotective substance in drug-induced experimental bladder cancer models. Moreover, recent studies have suggested that it is also effective in reducing intestinal inflammation in colitis. Because of the increased level of interest in using MESNA for treating various disorders, a new and sensitive method was needed to understand the pharmacokinetics of this drug. Accordingly, we developed a new method for determining free MESNA in biological samples by using ThioGlo-3 [3H-Naphto [2,1-b] pyran, 9-acetoxy-2-(4-(2,5-dihydro-2, 5-dioxo-1H-pyrrol-1-yl) phenyl-3-oxo)] as the derivatizing agent. MESNA was detected fluorimetrically by reverse-phase HPLC using acetonitrile:water (75:25) along with acetic acid and phosphoric acid (1 mL/L each) as the mobile phase. The detection limit was 1.64 nm per 20 microL injection volume, with a linearity (r = 0.999) in the calibration curve extending over a range 2.5-2500 nm. The coefficients of variation for within-run and between-run precision were 0.43 and 3.31%, respectively. The relative recoveries in the biological samples were in the range 87 +/- 6 to 93 +/- 2.4%. The concentrations of MESNA in the biological samples (lungs, liver, kidney and brain) were determined. The highest concentration of MESNA was found in plasma. Of all the tissues, the kidney was found to have the highest concentration while the liver had the lowest concentration.

Animals↗
PubMed2026

A Novel PTPN2 Isoform Differentially Regulates Immune Response.

Genome-wide association studies implicate the PTPN2 gene locus (18p11.21) in risk for several autoimmune diseases, including inflammatory bowel disease. Through genetic fine mapping, we identified the single-nucleotide polymorphism rs80262450 in the PTPN2 gene as the putative causal variant. Analysis of GTEx tissue samples and genetically engineered myeloid cell lines carrying risk and nonrisk alleles of rs80262450 demonstrated increased expression of the PTPN2 splice isoform 4 (PTPN2.4), suggesting that the rs80262450 enhances disease susceptibility by favoring production of PTPN2.4. Furthermore, we found that PTPN2.4 contains a nuclear export sequence (NES) that leads to its retention in the cytoplasm. Differential localization of PTPN2.4 isoform results in a distinct protein binding profile revealed by mass-spectrometry analysis, and its overexpression increased TNF-α. PTPN2.4 knockdown reduced pro-inflammatory cytokines in human macrophages. Mutations within the NES motif abolished the unique localization and function of PTPN2.4. Lastly, increased expression of PTPN2.4 was found in Crohn's disease tissues, demonstrating its involvement in the disease. Together, we identified the pathogenic isoform PTPN2.4 as a novel driver of intestinal inflammation and a potential target to attenuate inflammation in IBD.

Humans↗
PubMed2007

Multicenter randomized-controlled clinical trial of probiotics (Lactobacillus johnsonii, LA1) on early endoscopic recurrence of Crohn's disease after lleo-caecal resection.

BACKGROUND: Seventy percent of Crohn's disease (CD) patients exhibit anastomotic recurrence within 1 year after ileo-caecal surgery. Recent clinical trials suggest the beneficial use of probiotics in the control of intestinal inflammation in pouchitis and ulcerative colitis. This study is a multicenter clinical trial evaluating the efficacy of an oral administration of the probiotic LAl on early post-operative endoscopic recurrence of CD. METHODS: Seventy patients with CD were enrolled prior to elective ileo-caecal resection and randomly assigned after surgery to daily treatment with either Lactobacillus johnsonii, LA1, Nestle (1010 colony-forming units, CFU) (group A, n = 34) or placebo (group B, n = 36) for 12 weeks. The primary objective was to assess the effect of LAl on the endoscopic recurrence rate at 12 weeks. Stratification was performed according to smoking status at randomization. RESULTS: Seven and 14 patients were excluded in the LA1 and placebo groups, respectively. In intention-to-treat analysis, the mean endoscopic score was not significantly different between the two treatment groups at 3 months (LA1 versus placebo: 1.50 +/- 1.32 versus 1.22+/-1.37, treatment effect: P = 0.48, smoke effect: P = 0.72). The percentage of patients with severe recurrence (i3 + i4) was 21% and 15% in the LAl and placebo groups, respectively (P = 0.33). Using a per-protocol (PP) analysis, the mean endoscopic score was not significantly different between the two treatment groups (LAl versus placebo groups: 1.44 +/-1.31 versus 1.05 +/- 1.21, P = 0.32). The percentage of patients with severe recurrence (i3 + i4) was 19% and 9% in the LAl and placebo groups, respectively (P = 0.054). Clinical relapse rate (CDAI [CD activity index] > 150, with an increase of CDAI > 70 points or greater from baseline) in the LAl and placebo groups was 15% (4/27) and 13.5% (3/22), respectively (PP analysis: chi-square test, P = 0.91 and log-rank test: P = 0.79). CONCLUSION: Oral administration of the probiotic LA1 in patients with CD failed to prevent early endoscopic recurrence at 12 weeks after ileo-caecal resection.

Adolescent↗
PubMed2007

Neurotensin stimulates expression of early growth response gene-1 and EGF receptor through MAP kinase activation in human colonic epithelial cells.

Neurotensin (NT) is a highly expressed gastrointestinal (GI) neuropeptide, which modulates GI motility, secretion and cell growth as well as intestinal inflammation. Since EGF receptor is highly expressed in human colon cancer cells, we sought to examine whether NT stimulation contributes to the EGFR overexpression using nontransformed colonocyte NCM460 cells. The results show that NT treatment caused a significant increase in EGFR protein expression and gene transcription. Pretreatment with MAP kinase pathway inhibitor PD98059 blocked NT-induced EGFR expression. As the EGFR promoter has a functional Egr-1 site, previously shown to mediate its transcription in response to hypoxia, we examined the role of Egr-1 in the NT response. We first show that NT stimulated Egr-1 expression, which can be inhibited by PD98059. We also determined whether NT increases Egr-1 binding to its site within the EGFR promoter. The data indicate that NT enhanced the amount of Egr-1 binding to the EGFR Egr-1 site and that this binding was significantly decreased by PD98059. To verify that Egr-1 mediated NT-induced EGFR transcription, Egr-1 siRNA was used to knock down its expression. The data show that transfection of Egr-1 siRNA significantly inhibited NT-stimulated EGFR transcription. Together, our results suggest that NT can stimulate MAP kinase-mediated Egr-1 and EGFR gene expression in human colonocytes. Our results may be relevant to the mechanisms by which NT participates in the development of colon cancer.

Cell Line↗
PubMed2006

Ghrelin stimulates interleukin-8 gene expression through protein kinase C-mediated NF-kappaB pathway in human colonic epithelial cells.

Ghrelin, a newly identified gastric peptide, is known for its potent activity in growth hormone (GH) release and appetite. Although ghrelin is involved in several other responses such as stress and intestinal motility, its potential role in intestinal inflammation is not clear. Here, we show that expression of ghrelin and its receptor mRNA is significantly increased during acute experimental colitis in mice injected intracolonically with trinitrobenzene sulfate (TNBS). We found by PCR that ghrelin receptor mRNA is expressed in non-transformed human colonic epithelial NCM460 cells. Exposure of NCM460 cells stably transfected with ghrelin receptor mRNA to ghrelin, increased IkappaBalpha phosphorylation and its subsequent degradation. In addition, ghrelin stimulated NF-kappaB-binding activity and NF-kappaB p65 subunit phosphorylation, and induced IL-8 promoter activity and IL-8 protein secretion. Furthermore, our data show that ghrelin-induced IkappaBalpha and p65 phosphorylation was markedly reduced by pharmacological inhibitors of intracellular calcium mobilization (BAPTA/AM) and protein kinase C (GF 109203X). Pretreatment with BAPTA/AM or GF109203X also significantly attenuated ghrelin-induced IL-8 production. Together, our results strongly suggest that ghrelin may be a proinflammatory peptide in the colon. Ghrelin may participate in the pathophysiology of colonic inflammation by inducing PKC-dependent NF-kappaB activation and IL-8 production at the colonocyte level.

Animals↗
PubMed2005

Structural elucidation and analysis of thermal degradation products of the Fusarium mycotoxin nivalenol.

The major class of mycotoxins produced by Fusarium moulds are trichothecenes, a large group of sesquiterpenes sharing the same basic chemical structure, a 12,13-epoxytrichothec-9-ene ring system. Their toxic effects range from causing diarrhoea, vomiting and gastro-intestinal inflammation to noncompetitive inhibition of the biosynthesis of proteins in eukaryotic cells. Trichothecenes in general are relatively stable compounds, their degradation is observed only at high temperatures and prolonged heating time. In order to investigate the stability of the trichothecene nivalenol (NIV) under food processing conditions such as cooking or baking, we performed model heating experiments and screened the residue for degradation products using gas chromatography-mass spectrometry (GC-MS). Heating of nivalenol, especially under mild alkaline conditions, gave a mixture of four compounds (norNIV A, norNIV B, norNIV C, and NIV lactone), which where isolated and identified by nuclear magnetic resonance (NMR) and MS experiments. Although their formation was also demonstrated in heating experiments with spiked flour samples, only norNIV B was detectable in a screening of several commercially available samples, possibly due to the very low contamination with nivalenol. Furthermore, cell culture experiments using immortalized human kidney epithelial (IHKE) cells showed that the four compounds are less cytotoxic (formazan dye cytotoxicity assay) compared to nivalenol. Whereas nivalenol revealed an EC50 at 0.9 micromol, all other compounds did not show any significant effect up to 100 micromol.

Cell Line, Transformed↗
PubMed2006

Stable isotope dilution analysis of the Fusarium mycotoxins deoxynivalenol and 3-acetyldeoxynivalenol.

Trichothecenes are secondary metabolites produced by several fungi of the Fusarium genus during their growth period. They inhibit protein biosynthesis in eukaryotic cells resulting in numerous toxic effects such as diarrhea, vomiting, and gastro-intestinal inflammation. Considering its occurrence in food and feedstuff, deoxynivalenol (DON) is one of the most important trichothecenes. We report the synthesis of stable isotope labeled 15-d(1)-deoxynivalenol (15-d(1)-DON) from its natural precursor 3-acetyldeoxynivalenol (3-AcDON) as starting material. Furthermore, a method for the analysis of DON and 3-AcDON using HPLC-MS/MS with stable isotope labeled 15-d(1)-DON and 3-d(3)-AcDON as internal standards has been developed. In total, 18 cereal product samples were analyzed with contamination levels ranging from 10-301 microg/kg for DON and 5-14 microg/kg for 3-AcDON. This is the first report of an isotope dilution MS method for the analysis of type B-trichothecenes.

Chromatography, High Pressure Liquid↗