Gastrin activates nuclear factor kappaB (NFkappaB) through a protein kinase C dependent pathway involving NFkappaB inducing kinase,inhibitor kappaB (IkappaB) kinase,and tumour necrosis factor receptor associated factor 6 (TRAF6) in MKN-28 cells transfected with gastrin receptor

BACKGROUND: We previously reported that gastrin induces expression of CXC chemokines through activation of nuclear factor kappaB (NFkappaB) in gastric epithelial cells that express gastrin receptor. AIMS: To clarify gastrin receptor mediated signals leading to activation of NFkappaB. METHODS: MKGR26 cells were created by transfecting gastrin receptor cDNA into MKN-28 cells. Degradation of inhibitor kappaB (IkappaB) and phosphorylation of protein kinase C (PKC)-delta were both detected by western blot analysis. NFkappaB activation was determined by luciferase assay and electrophoretic mobility shift analysis. RESULTS: Gastrin induced degradation of IkappaB-alpha and activation of NFkappaB, which was abolished by the selective gastrin receptor antagonist L-740,093 and the general PKC inhibitor GF109203X. Gastrin induced phosphorylation of PKC-delta, and its inhibitor rottlerin partially suppressed NFkappaB activation. However, the mitogen activated protein kinase (MAPK) kinase inhibitor PD98059, p38 MAPK inhibitor SB203580, and tyrphostin AG1478 had no effect on NFkappaB activation. Introduction of the dominant negative mutant of IkappaB kinase, of NFkappaB inducing kinase, and of tumour necrosis factor receptor associated factor 6 (TRAF6), but not that of TRAF2, inhibited gastrin induced activation of NFkappaB. CONCLUSIONS: Gastrin activates NFkappaB via a PKC dependent pathway which involves IkappaB kinase, NFkappaB inducing kinase, and TRAF6.     

Altered colonic glycoprotein expression in unaffected monozygotic twins of inflammatory bowel disease patients

BACKGROUND AND AIMS: Previous chromatographic analysis of colonic mucins from monozygotic twins with inflammatory bowel disease (IBD) suggested a genetic mucin alteration in ulcerative colitis (UC). This study explores this further by assessing mucosal expression of the oncofetal carbohydrate antigen TF (galactose beta1, 3 N-acetylgalactosamine alpha-), among the same IBD twins. MATERIALS AND METHODS: Formalin fixed paraffin embedded rectal biopsies were studied from 22 monozygotic twin pairs with IBD. These included eight UC twin pairs and 14 Crohn's disease (CD) twin pairs, with six pairs concordant for disease and 16 unaffected twin siblings. Closely adjacent sections were assessed by peanut lectin histochemistry for TF expression and immunohistochemically for nuclear factor kappaB (NFkappaB) activation with investigators blinded to the diagnosis. RESULTS: Unaffected twins were almost all TF positive (15/16) compared with 5/29 histologically normal controls (p<0.0001). Unaffected UC (7/8) and CD twins (8/8) were similarly TF positive. TF positivity was confined mainly to the superficial epithelium and absent from the stem cell compartment of the lower crypts, suggesting that glycosylation changes are acquired rather than genetically determined. Activated NFkappaB was present in the surface epithelium of mucosal biopsies from 13/14 unaffected IBD twins but in only 6/22 histologically normal controls (p=0.0004). All 22 affected IBD twins were TF positive and 18 were positive for activated NFkappaB. CONCLUSIONS: Altered mucosal glycosylation in unaffected identical twins of IBD patients was confirmed in this study. This occurred in both UC and CD twins. The changes are probably acquired rather than congenital and may reflect "preinflammatory" NFkappaB activation.     

Trefoil factors in inflammatory bowel disease

Inflammatory bowel disease(IBD),which comprises ulcerative colitis and Crohn’s disease,is characterized by inflammation of the gastrointestinal tract.The trefoil factors 1,2,and 3(TFF1-3)are a family of peptides that play important roles in the protection and repair of epithelial surfaces,including the gastrointestinal tract.TFFs may be involved in IBD pathogenesis and are a potential treatment option.In the present review,we describe the TFF family and their potential role in IBD by summarizing the current knowledge of their expression,possible function and pharmacological role in IBD.     

Increased activation of nuclear factor kappaB triggers inflammation and insulin resistance in polycystic ovary syndrome

CONTEXT: Insulin resistance and chronic low level inflammation are often present in women with polycystic ovary syndrome (PCOS). OBJECTIVE: The purpose of this study was to determine the effects of hyperglycemia on nuclear factor kappaB (NFkappaB) activation and inhibitory kappaB (IkappaB) from mononuclear cells (MNC) in PCOS. DESIGN AND SETTING: This was a prospective controlled study conducted at an academic medical center. PATIENTS: The study population consisted of 16 reproductive-age women with PCOS (eight lean, eight obese) and 16 age- and body composition-matched controls (eight lean, eight obese). MAIN OUTCOME MEASURES: Insulin sensitivity (IS) was derived from a 2-h 75-g oral glucose tolerance test (IS(OGTT)). Intranuclear NFkappaB and IkappaB protein expression were quantitated from MNC obtained from blood drawn fasting and 2 h after glucose ingestion. RESULTS: IS(OGTT) was lower in PCOS compared with controls (3.3 +/- 0.3 vs. 6.4 +/- 0.9, P < 0.004). The percent change in intranuclear NFkappaB was higher in lean and obese PCOS compared with lean controls (42.5 +/- 19.1 and 54.5 +/- 12.5 vs. -14.1 +/- 10.9, P < 0.006). The percent change in intranuclear NFkappaB correlated positively with 2-h post-glucose ingestion levels (r = 0.37; P < 0.04) and plasma testosterone (r = 0.49; P < 0.006) and correlated negatively with IS(OGTT) (r = 0.39; P < 0.04). The percent change in IkappaB was lower in lean and obese PCOS compared with lean controls (-22.3 +/- 3.2 and -17.0 +/- 5.0 vs. 8.4 +/- 11.8, P < 0.02). CONCLUSION: In response to hyperglycemia, intranuclear NFkappaB increases and IkappaB decreases in MNC of women with PCOS independent of obesity. This may represent a cardinal inflammatory signal that contributes to the induction of insulin resistance and hyperandrogenism in PCOS.     

Anti-inflammatory effects of pancreatitis associated protein in inflammatory bowel disease

BACKGROUND AND AIMS: Increased pancreatitis associated protein (PAP) mRNA has been reported in active inflammatory bowel disease (IBD). The aims of the current study were to characterise PAP production in IBD and the effects of PAP on inflammation. PATIENTS AND METHODS: Serum PAP levels were determined in healthy controls (n = 29), inflammatory controls (n = 14), and IBD patients (n = 171). Ex vivo PAP secretion in intestinal tissue was measured in 56 IBD patients and 13 healthy controls. Cellular origin of PAP was determined by immunohistochemistry. The effects of exogenous PAP on nuclear factor kappaB (NFkappaB) activation, proinflammatory cytokine production, and endothelial adhesion molecule expression were also analysed ex vivo. RESULTS: Patients with active IBD had increased serum PAP levels compared with controls, and these levels correlated with clinical and endoscopic disease severity. Ex vivo intestinal PAP synthesis was increased in active IBD and correlated with endoscopic and histological severity of inflammatory lesions. PAP localised to colonic Paneth cells. Incubation of mucosa from active Crohn's disease with PAP dose dependently reduced proinflammatory cytokines secretion. PAP prevented TNF-alpha induced NFkappaB activation in monocytic, epithelial, and endothelial cells and reduced proinflammatory cytokine mRNA levels and adhesion molecule expression. CONCLUSIONS: PAP is synthesised by Paneth cells and is overexpressed in colonic tissue of active IBD. PAP inhibits NFkappaB activation and downregulates cytokine production and adhesion molecule expression in inflamed tissue. It may represent an anti-inflammatory mechanism and new therapeutic strategy in IBD.     

Loss of transforming growth factor beta signalling in the intestine contributes to tissue injury in inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract caused by an abnormal and uncontrolled immune response to one or more normally occurring gut constituents. AIM: Given the effects of transforming growth factor beta1 (TGF-beta1) on both the immune system and extracellular matrix, we postulated that alterations in TGF-beta signalling in intestinal epithelial cells may play an important role in the development of IBD. METHODS: TGF-beta signalling was inactivated in mouse intestine by expressing a dominant negative mutant form of the TGF-beta type II receptor under the control of the mouse intestinal trefoil peptide (ITF)/TFF3 promoter. Transgenic mice (ITF-dnRII) developed spontaneous colitis presenting with diarrhoea, haematochezia, and anal prolapse when not maintained under specific pathogen free (SPF) conditions. Under SPF conditions we induced colitis by mixing dextran sodium sulphate (DSS) in drinking water to examine the significance of loss of TGF-beta signalling in the pathogenesis of IBD. RESULTS: Transgenic mice showed increased susceptibility to DSS induced IBD, and elicited increased expression of major histocompatibility complex class II, generation of autoantibodies against intestinal goblet cells, and increased activity of matrix metalloproteinase in intestinal epithelial cells compared with wild-type littermates challenged with DSS. CONCLUSIONS: Deficiency of TGF-beta signalling specifically in the intestine contributes to the development of IBD. Maintenance of TGF-beta signalling may be important in regulating immune homeostasis in the intestine     

DNA from probiotic bacteria modulates murine and human epithelial and immune function

BACKGROUND & AIMS: The intestinal epithelium must discriminate between pathogenic and nonpathogenic bacteria and respond accordingly. The aim of this study was to examine whether bacterial DNA can serve as the molecular basis for bacterial recognition. METHODS: HT-29 monolayers were treated with various bacterial DNA and interleukin (IL)-8 secretion measured by enzyme-linked immunosorbent assay, nuclear factor kappaB activation by electrophoretic mobility shift assay and reporter assays, and IkappaB levels by Western blotting. Cytokine secretion in response to bacterial DNA was measured in murine colonic segments and splenocytes. IL-10-deficient mice were fed DNA from VSL probiotic compound daily for 2 weeks. Colons were removed and analyzed for cytokine production and inflammation. RESULTS: HT-29 cells responded with IL-8 secretion to bacterial DNA in a differential manner. In the presence of proinflammatory stimuli, VSL3 DNA inhibited IL-8 secretion, reduced p38 mitogen-activated protein kinase activation, delayed nuclear factor kappaB activation, stabilized levels of IkappaB, and inhibited proteasome function. VSL3 DNA inhibited colonic interferon (IFN)-gamma secretion in mouse colons and also attenuated a Bacteroides vulgatus-induced IFN-gamma release from murine splenocytes. In mice, VSL3 DNA attenuated a systemic release of tumor necrosis factor alpha in response to Escherichia coli DNA injection. Treatment of IL-10-deficient mice with oral VSL3 DNA resulted in a reduction in mucosal secretion of tumor necrosis factor alpha and IFN-gamma and an improvement in histologic disease. CONCLUSIONS: DNA from probiotic bacteria can limit epithelial proinflammatory responses in vivo and in vitro. Systemic and oral administration of VSL3 DNA ameliorates inflammatory responses.     

Serum trefoil factors in patients with inflammatory bowel disease

BACKGROUND: Trefoil factors (TFF1-3) play a critical role in mucosal protection and repair in the gastrointestinal tract. The aims of the present study were to examine associations between serum TFF1-3 and clinical and biochemical markers reflecting disease activity and to examine changes in TFF1-3 in patients with inflammatory bowel disease (IBD) before and during high-dose prednisolone treatment and tapering. METHODS: Serum concentrations of TFF1-3 were quantified in 48 ulcerative colitis (UC) and 50 Crohn's disease (CD) patients with little or moderate activity. Additionally, serum TFF concentrations were determined in patients with severe activity in colon IBD (4 UC and 6 CD) before and during prednisolone treatment with 7 healthy subjects as controls. RESULTS: Median concentrations of TFF1, TFF2, and TFF3 were significantly increased in IBD patients compared with healthy controls (p < 0.01). TFF3 concentrations correlated with clinical and biochemical parameters of disease activity in UC patients. In addition, a trend towards reduction in TFF concentrations during treatment with prednisolone and concomitant clinical and biochemical remission was observed. CONCLUSIONS: The present data support the concept that trefoil peptides are upregulated and may play a role in IBD mucosal protection and repair. In UC patients, TFF3 levels were increased in active disease levels correlated with disease activity indices. Due to a large variation, serum TFFs are not a potential marker for disease activity.     

Mu opioid receptor expression is increased in inflammatory bowel diseases: implications for homeostatic intestinal inflammation

BACKGROUND AND AIMS: Recent studies with mu opioid receptor (MOR) deficient mice support a physiological anti-inflammatory effect of MOR at the colon interface. To better understand the potential pharmacological effect of certain opiates in inflammatory bowel diseases (IBD), we (1) evaluated the regulation in vivo and in vitro of human MOR expression by inflammation; and (2) tested the potential anti-inflammatory function of a specific opiate (DALDA) in inflamed and resting human mucosa. PATIENTS AND METHODS: Expression of MOR mRNA and protein was evaluated in healthy and inflamed small bowel and colonic tissues, isolated peripheral blood mononuclear cells and purified monocytes, and CD4+ and CD8+ T cells from healthy donors and IBD patients. The effect of cytokines and nuclear factor kappaB (NFkappaB) activation on MOR expression in lymphocyte T and monocytic human cell lines was assessed. Finally, DALDA induced anti-inflammatory effect was investigated in mucosal explants from controls and IBD patients. RESULTS: MOR was expressed in ileal and colonic enteric neurones as well as in immunocytes such as myeloid cells and CD4+ and CD8+ T cells. Overexpressed in active IBD mucosa, MOR was significantly enhanced by cytokines and repressed by NFkappaB inhibitor in myeloid and lymphocytic cell lines. Furthermore, ex vivo DALDA treatment dampened tumour necrosis factor alpha mRNA expression in the colon of active IBD patients. CONCLUSIONS: Given the increased expression of MOR and the ex vivo beneficial effect of DALDA in active IBD, natural and/or synthetic opioid agonists could help to prevent overt pathological intestinal inflammation.     

Glial-derived neurotrophic factor regulates apoptosis in colonic epithelial cells

BACKGROUND & AIMS: Ablation of the enteric glia leads to a fulminant hemorrhagic jejunoileitis. We hypothesized that glial-derived neurotrophic factor (GDNF) may be involved in mucosal protection of the gut. Therefore, we examined the regulation of GDNF and its receptor (GFR-alpha1) in colonic inflammation and its effects on colonic epithelial cell apoptosis. METHODS: The expression of GDNF and GFR-alpha1 was investigated in experimental colitis of rats and in human inflammatory bowel disease (IBD). GDNF-induced activation of Akt (protein kinase B [PKB]) and mitogen-activated protein kinase (MAPK) in the colonic epithelial cell lines HT-29 and SW480 was studied. Furthermore, the antiapoptotic potency of GDNF in SW480 cells was evaluated. RESULTS: GDNF was specifically up-regulated in experimental rat colitis and in IBD. In contrast, GFR-alpha1 was constitutively expressed in rat and human colonic epithelium. GDNF potently activated MAPK and Akt (PKB) in colonic epithelial cells. Moreover, GDNF strongly prevented apoptosis in SW480 cells. Our data show that GDNF-mediated protection against apoptosis depends on activation of the MAPK and phosphatidylinositol 3-kinase/Akt (PKB) pathways. CONCLUSIONS: GDNF is up-regulated in IBD and has strong antiapoptotic properties in colonic epithelial cells. This points to a novel role of the neurotrophic factor GDNF for mucosal protection and regeneration in IBD.