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PubMed2002

Clinical aspects and pathophysiology of inflammatory bowel disease.

The chronic inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis, are recognized as important causes of gastrointestinal disease in children and adults. In this review we delineate the clinical manifestations and diagnostic features of IBD. In addition, we summarize important recent advances in our understanding of the immune mediators of intestinal inflammation. This information has led to new therapeutic approaches in IBD. Further, we discuss the considerable data that point to the significance of genetic factors in the development of IBD and the genetic loci which have been implicated through genome-wide searches. The commensal bacterial flora also appears to be a critical element, particularly in regards to Crohn's disease, although the precise role of the bacteria in the disease manifestations remains unclear. Current investigations promise to yield fresh insights in these areas.

Adult↗
PubMed1983

Enhancement of experimental ulcerative colitis by immunization with Bacteroides vulgatus.

Previous studies with the guinea pig model for ulcerative colitis have shown that the inducing agent, carrageenan, does not provoke ulcerations in germfree guinea pigs, but animals monoassociated with Bacteroides vulgatus develop cecal ulcerations when fed carrageenan. In an effort to define the role of B. vulgatus in this model system, conventional guinea pigs were immunized with B. vulgatus before carrageenan treatment. Immunized animals developed both circulating antibody and positive skin tests for the homologous antigen. A comparison of B. vulgatus-immune and nonimmune carrageenan recipients after 30 days of carrageenan treatment revealed ulcerations of the ceca and large intestine in both groups, but the immune group developed more severe lesions than the nonimmune group. The most severe intestinal lesions were detected in B. vulgatus-immune animals fed both carrageenan and daily doses of viable B. vulgatus. Immune recipients of B. vulgatus alone did not develop ulcerations, but showed histological evidence of intestinal inflammation. Lesions observed in B. vulgatus-immune animals were most severe in the colon and rectum, in contrast to more severe cecal lesions detected in nonimmune carrageenan recipients. Similar experiments with Bacteroides fragilis as an antigen for immunization showed no difference between immune and nonimmune groups. These results suggest that immunization with B. vulgatus enhances the severity of carrageenan-induced colitis.

Animals↗
PubMed2002

A monoclonal antibody to the amebic lipophosphoglycan-proteophosphoglycan antigens can prevent disease in human intestinal xenografts infected with Entamoeba histolytica.

Entamoeba histolytica trophozoites are covered by lipophosphoglycan-peptidoglycan molecules which may be key virulence factors. We found that pretreatment of severe combined immunodeficient mice bearing human intestinal xenografts with a monoclonal antibody to the amebic lipophosphoglycan-peptidoglycan molecules can prevent or significantly reduce the human intestinal inflammation and tissue damage that are normally seen with E. histolytica colonic infection.

Animals↗
PubMed2003

Analysis of gene expression in ceca of Helicobacter hepaticus-infected A/JCr mice before and after development of typhlitis.

The inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract. The causes of these diseases remain unknown; however, prevailing theories suggest that chronic intestinal inflammation results from a dysregulated immune response to ubiquitous bacterial antigens. While a substantial body of data has been amassed describing the role of the adaptive immune system in perpetuating and sustaining inflammation, very little is known about the early signals, prior to the development of inflammation, that initiate and direct the abnormal immune response. To this end, we characterized the gene expression profile of A/JCr mice with Helicobacter hepaticus-induced typhlitis at month 1 of infection, prior to the onset of histologic disease, and month 3 of infection, after chronic inflammation is fully established. Analysis of the gene expression in ceca of H. hepaticus infected mice revealed 25 up-regulated and 3 down-regulated genes in the month-1 postinoculation group and 31 up-regulated and 2 down-regulated genes in the month-3 postinoculation group. Among these was a subset of immune-related genes, including interferon-inducible protein 10, monokine induced by gamma interferon, macrophage-induced protein 1 alpha, and serum amyloid A1. Semiquantitative real-time reverse transcriptase PCR confirmed the increased expression levels of these genes, as well as elevated expression of gamma interferon. To our knowledge, this is the first report profiling cecal gene expression in H. hepaticus-infected A/JCr mice. The findings of altered gene expression prior to the development of any features of pathology and the ensuing chronic disease course make this an attractive model for studying early host response to microbe-induced inflammatory bowel disease.

Animals↗
PubMed2004

Cooperative interactions between flagellin and SopE2 in the epithelial interleukin-8 response to Salmonella enterica serovar typhimurium infection.

Flagellin is an important stimulus for epithelial interleukin-8 (IL-8) secretion because of its ability to activate Toll-like receptor 5 (TLR5). SopE2, a Salmonella guanine nucleotide exchange factor (GEF), is also involved in intestinal inflammation. To clarify the proinflammatory mechanisms of these proteins, we examined their effects on IL-8 secretion and intracellular signaling in T84 epithelial cells. A Salmonella strain lacking SopE2 (and its homolog SopE) induced lower levels of IL-8 than the wild type and exhibited reduced activation of mitogen-activated protein kinases (MAPKs). Overexpression of wild-type SopE2 in this strain restored MAPK activation and augmented IL-8 production, whereas a mutant lacking GEF activity failed to increase IL-8 expression. Additional effects on signaling were demonstrated in transient transfection experiments, in which SopE2 enhanced the ability of TRAF6, a signal transducer downstream of TLR5, to activate the NF-kappaB transcription factor in 293 cells. Flagellin was also found to be required for IL-8 induction in T84 cells. In its absence, the ability of SopE2 overexpression to increase IL-8 secretion was impaired. Part of this impairment was related to the decreased motility of the flagellin-deficient strain, but lack of flagellin also affected translocation of SopE2 into the infected cells. Our results indicate that flagellin and SopE2 interact functionally at multiple levels to increase IL-8 secretion by epithelial cells-flagellin facilitating the translocation of SopE2, and SopE2 enhancing signaling pathways activated by flagellin. These observations offer a mechanistic explanation for the involvement of these proteins in the pathogenesis of Salmonella-induced gastroenteritis.

Bacterial Proteins↗
PubMed2005

Probiotic Lactobacillus spp. diminish Helicobacter hepaticus-induced inflammatory bowel disease in interleukin-10-deficient mice.

Clinical and experimental evidence has demonstrated the potential role of probiotics in the prevention or treatment of inflammatory bowel disease. Probiotic clones with direct immunomodulatory activity may have anti-inflammatory effects in the intestine. We investigated the roles of tumor necrosis factor alpha (TNF-alpha)-inhibitory Lactobacillus clones with a pathogen-induced murine colitis model. Murine-derived probiotic lactobacilli were selected in vitro for their ability to inhibit TNF-alpha secretion by Helicobacter hepaticus-stimulated macrophages. Interleukin-10 (IL-10)-deficient mice were treated with probiotic Lactobacillus reuteri in combination with Lactobacillus paracasei and then challenged with H. hepaticus. Ten weeks postinoculation, the severity of typhlocolitis was assessed by histologic examination of the cecocolic region. Intestinal proinflammatory cytokine responses were evaluated by real-time quantitative reverse transcriptase PCR and immunoassays, and the quantities of intestinal H. hepaticus were evaluated by real-time PCR. Intestinal colonization by TNF-alpha-inhibitory lactobacilli reduced intestinal inflammation in H. hepaticus-challenged IL-10-deficient mice despite similar quantities of H. hepaticus in cocolonized animals. Proinflammatory colonic cytokine (TNF-alpha and IL-12) levels were lowered in Lactobacillus-treated animals. In this H. hepaticus-challenged IL-10-deficient murine colitis model, lactobacilli demonstrated probiotic effects by direct modulation of mucosal inflammatory responses.

Animals↗
PubMed2005

Concurrent infection with an intestinal helminth parasite impairs host resistance to enteric Citrobacter rodentium and enhances Citrobacter-induced colitis in mice.

Infections with intestinal helminth and bacterial pathogens, such as enteropathogenic Escherichia coli, continue to be a major global health threat for children. To test the hypothesis that intestinal helminth infection may be a risk factor for enteric bacterial infection, a murine model was established by using the intestinal helminth Heligomosomoides polygyrus. To analyze the modulatory effect of a Th2-inducing helminth on the outcome of enteric bacterium Citrobacter rodentium infection, BALB/c and STAT 6 knockout (KO) mice were infected with H. polygyrus, C. rodentium, or both. We found that only BALB/c mice coinfected with H. polygyrus and C. rodentium displayed a marked morbidity and mortality. The enhanced susceptibility to C. rodentium and intestinal injury of coinfected BALB/c mice were shown to be associated with a significant increase in helminth-driven Th2 responses, mucosally and systemically, and correlated with a significant downregulation of protective gamma interferon and with a dramatic upregulation of the proinflammatory tumor necrosis factor alpha response. In addition, C. rodentium-associated colonic pathology in coinfected BALB/c mice was significantly enhanced, whereas bacterial burden was increased and clearance was delayed. In contrast, coinfection in STAT 6 KO mice failed to promote C. rodentium infection or to induce a more severe intestinal inflammation and tissue injury, demonstrating a mechanism by which helminth influences the development of host protective immunity and susceptibility to bacterial infections. We conclude that H. polygyrus coinfection can promote C. rodentium-associated disease and colitis through a STAT 6-mediated immune mechanism.

Animals↗
PubMed2006

MyD88-dependent pathways mediate resistance to Cryptosporidium parvum infection in mice.

Cryptosporidium spp. cause diarrheal disease worldwide. Innate immune responses mediating resistance to this parasite are not completely understood. To determine whether MyD88-dependent pathways play a role in resistance to Cryptosporidium parvum, we compared the course of infection in MyD88(-/-) mice to that in their wild-type (WT) littermate controls. Three- to 4-week-old mice were infected with C. parvum, and infection was monitored by quantifying fecal oocyst shedding. Twelve days postinfection, the histology of the intestines was examined to quantify intestinal parasite burden and to determine if there were any pathological changes. Fecal oocyst shedding and intestinal parasite burden were significantly greater in MyD88(-/-) mice than in littermate controls. Nonetheless, both WT and MyD88(-/-) mice cleared the infection within 3 weeks. These results indicate that MyD88-dependent pathways are involved in mediating initial resistance to C. parvum. Since gamma interferon (IFN-gamma) is known to mediate resistance to C. parvum, we also studied infection in MyD88(-/-) mice and WT controls in which this cytokine was temporarily neutralized. Fecal oocyst shedding, as well as intestinal parasite burden, intestinal inflammation, and mortality, was significantly greater in MyD88(-/-) mice in which IFN-gamma was neutralized than in IFN-gamma-neutralized WT mice or in MyD88(-/-) mice in which this cytokine was active. These results suggest that MyD88 and IFN-gamma had an additive effect in conferring protection from C. parvum infection. While this study confirms the importance of IFN-gamma in conferring resistance to infection with C. parvum, it suggests that MyD88-mediated pathways also play a role in innate immunity to this parasite.

Adaptor Proteins, Signal Transducing↗
PubMed2003

MMR vaccine--how effective and how safe?

The introduction of combined measles, mumps and rubella (MMR) vaccine into the UK childhood immunisation schedule in 1988 has markedly reduced the incidence of these diseases and their complications, with, for example, no deaths from acute measles occurring since 1992. However, uptake of MMR vaccine has fallen since the publication, in 1998, of a study that suggested a link between exposure to the vaccine and the development of intestinal inflammation and autism. The study, and the subsequent debate, have attracted considerable media coverage and left many parents and some healthcare professionals uncertain about what to do. While in 1996, 92% of children in England and Wales had received their first dose of the vaccine by the age of 2 years, by 2001-2 this figure had fallen to 84%, with much lower uptake in some regions, threatening a resurgence of all three diseases. Here, we review the evidence for the effectiveness and safety of MMR vaccine.

Attitude to Health↗
PubMed2005

Production of adiponectin, an anti-inflammatory protein, in mesenteric adipose tissue in Crohn's disease.

BACKGROUND AND AIMS: A characteristic feature of Crohn's disease (CD) is mesenteric adipose tissue hypertrophy. Mesenteric adipocytes or specific proteins secreted by them may play a role in the pathogenesis of CD. We recently identified adiponectin as an adipocyte specific protein with anti-inflammatory properties. Here we report on expression of adiponectin in mesenteric adipose tissue of CD patients. METHODS AND RESULTS: Mesenteric adipose tissue specimens were obtained from patients with CD (n = 22), ulcerative colitis (UC) (n = 8) and, for controls, colon carcinoma patients (n = 28) who underwent intestinal resection. Adiponectin concentrations were determined by enzyme linked immunosorbent assay, and adiponectin mRNA levels were determined by real time quantitative reverse transcription-polymerase chain reaction. Tissue concentrations and release of adiponectin were significantly increased in hypertrophied mesenteric adipose tissue of CD patients compared with normal mesenteric adipose tissue of CD patients (p = 0.002, p = 0.040, respectively), UC patients (p = 0.002, p = 0.003), and controls (p<0.0001, p<0.0001). Adiponectin mRNA levels were significantly higher in hypertrophied mesenteric adipose tissue of CD patients than in paired normal mesenteric adipose tissue from the same subjects (p = 0.024). Adiponectin concentrations in hypertrophied mesenteric adipose tissue of CD patients with an internal fistula were significantly lower than those of CD patients without an internal fistula (p = 0.003). CONCLUSIONS: Our results suggest that adipocytes in hypertrophied mesenteric adipose tissue produce and secrete significant amounts of adiponectin, which could be involved in the regulation of intestinal inflammation associated with CD.

Adipocytes↗
PubMed2005

Regulatory CD4+CD25+ cells reverse imbalances in the T cell pool of bone marrow transplanted TGepsilon26 mice leading to the prevention of colitis.

BACKGROUND AND AIMS: Erroneous thymic selection of developing T lymphocytes may be responsible for the expansion of self reactive T cells or may contribute to the absence of regulatory T cells important in controlling peripheral inflammatory processes. Colitis in bone marrow (BM) transplanted Tgepsilon26 mice is induced by abnormally activated T cells developing in an aberrant thymic microenvironment. We investigated the protective role of regulatory CD4+CD25+ T cells in this model. METHODS: BM from (C57BL/6 x CBA/J) F1 mice was transplanted into specific pathogen free Tgepsilon26 mice (BM-->Tgepsilon26). Transplanted mice received no cells (control), sorted CD4+CD25+, or CD4+CD25- cells from mesenteric lymph nodes (MLN) of normal mice. MLN cell subsets were analysed using membrane markers. Cytokine secretion of MLN cells was measured using intracellular cytokine staining and cytokine secretion in anti-CD3 stimulated cell cultures. Colitis was measured by histological scores. RESULTS: CD4+CD25+ cells were reduced in the MLNs of BM-->Tgepsilon26 mice. Transfer of regulatory CD4CD4+CD25+ but not of CD4+CD25- cells reduced the number of MLN CD4+ T cells in BM-->Tgepsilon26 recipients and increased the number of MLN CD8+ cells, thereby normalising the CD4+/CD8+ ratio. CD4+CD25+ but not CD4+CD25- cell transfer into BM-->Tgepsilon26 mice reduced the number of tumour necrosis factor alpha+ CD4+ cells and increased the secretion of transforming growth factor beta by MLN cells. Transfer of 3 x 10(5) CD4+CD25+ cells after BM transplantation into Tgepsilon26 mice prevented colitis whereas CD4+CD25- cells had no protective effect. CONCLUSIONS: These results suggest that defective selection or induction of regulatory T cells in the abnormal thymus is responsible for the development of colitis in BM-->Tgepsilon26 mice. Transfer of CD4+CD25+ cells can control intestinal inflammation in BM-->Tgepsilon26 mice by normalising the number and function of the MLN T cell pool.

Animals↗
PubMed1987

Faecal alpha-1-antitrypsin and excretion of 111indium granulocytes in assessment of disease activity in chronic inflammatory bowel diseases.

Intestinal protein loss in chronic inflammatory bowel diseases may be easily determined by measurement of alpha-1-antitrypsin (alpha 1-AT) stool concentration and alpha 1-AT clearance. Both parameters were significantly raised in 36 and 34 patients respectively with chronic inflammatory bowel diseases, compared with eight patients with non-inflammatory bowel diseases, or 19 healthy volunteers. There was wide range of overlap between active and inactive inflammatory disease. Contrary to serum alpha 1-AT, faecal excretion and clearance of alpha 1-AT did not correlate with ESR, serum-albumin, orosomucoid, and two indices of disease activity. A comparison of alpha 1-AT faecal excretion and clearance with the faecal excretion of 111In labelled granulocytes in 27 patients with chronic inflammatory bowel diseases, showed no correlation between the intestinal protein loss and this highly specific marker of intestinal inflammation. Enteric protein loss expressed by faecal excretion and clearance of alpha 1-AT does not depend on mucosal inflammation only, but may be influenced by other factors.

Adolescent↗
PubMed1999

Efficient gene delivery to the inflamed colon by local administration of recombinant adenoviruses with normal or modified fibre structure.

BACKGROUND/AIMS: Replication deficient recombinant adenoviruses represent an efficient means of transferring genes in vivo into a wide variety of dividing and quiescent cells from many different organs. Although the gastrointestinal tract is a potentially attractive target for gene therapy approaches, only a few studies on the use of viral gene transfer vehicles in the gut have been reported. The prospects of using recombinant adenoviruses for gene delivery into epithelial and subepithelial cells of the normal and inflamed colon are here analysed. METHODS: An E1/E3 deleted recombinant adenovirus (denoted AdCMVbetaGal) and an adenovirus with modified fibre structure (denoted AdZ.F(pk7)) both expressing the bacterial lacZ gene under the control of a human cytomegalovirus promoter were used for reporter gene expression in vitro and in vivo. beta-Galactosidase activity was determined by specific chemiluminescent reporter gene assay. RESULTS: Intravenous or intraperitoneal injection of AdCMVbetaGal into healthy Balb/c mice caused strong reporter gene expression in the liver and spleen but not in the colon. In contrast, local administration of AdCMVbetaGal resulted in high reporter gene expression in colonic epithelial cells and lamina propria mononuclear cells. A local route of adenovirus administration in mice with experimental colitis induced by the hapten reagent trinitrobenzenesulphonic acid was next evaluated. Interestingly, rectal administration of AdCMVbetaGal caused a higher beta-galactosidase activity in isolated lamina propria cells from infected mice with experimental colitis than in those from controls. Furthermore, isolated lamina propria cells from mice with colitis infected in vitro showed a significant increase in reporter gene activity compared with controls. Finally, AdZ.F(pk7) adenoviruses with modified fibre structure produced 10- to 40-fold higher reporter gene activity in spleen T cells and lamina propria mononuclear cells of colitic mice compared with standard AdCMVbetaGal vectors. CONCLUSIONS: Local administration of recombinant adenoviruses with normal or modified fibre structure could provide a new reliable method for targeted gene expression in the inflamed colon. Such gene delivery could be used to specifically express signal transduction proteins with therapeutic potential in inflamed colonic tissue. In particular, adenoviruses with modified fibre structure may be useful in T cell directed therapies in intestinal inflammation.

Adenoviridae↗
PubMed1999

Synergistic effects of interferon gamma and tumour necrosis factor alpha on T84 cell function.

BACKGROUND: Inflammatory bowel disease (IBD) is characterised by chronic intestinal inflammation and increased epithelial permeability. Both tumour necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) have been implicated in IBD. AIMS: To understand better the effects of these cytokines on epithelial cell function. METHODS: T84 cells were cultured with IFN-gamma and TNF-alpha and changes in transepithelial resistance (TER), fluorescein isothiocyanate (FITC) dextran flux, short circuit current (I(sc)), cystic fibrosis transmembrane conductance regulator (CFTR) protein levels, cell morphology, TNF receptor gene expression, and apoptosis were assayed. RESULTS: Relative to controls, significant changes (p<0.05) occurred in cells incubated with IFN-gamma for two days: TER was decreased to 20 (6.2)%, FITC-dextran flux was increased by 109 (19)-fold, cAMP and Ca dependent I(sc) were decreased to 51 (6.4)% and 24 (2.2)%, respectively, and CFTR levels were decreased to 47 (11)%. Cell morphology was altered but cell death was not induced. TNF receptor mRNA levels were increased. When added with IFN-gamma, TNF-alpha accelerated IFN-gamma dependent changes. Relative to controls, significant changes occurred after one day of culture with IFN-gamma plus TNF-alpha: TER was decreased to 27 (3.5)%, FITC-dextran flux was increased by 185 (45)-fold, and cAMP and Ca dependent I(sc) were decreased to 66 (12)% and 35 (6.8)%, respectively. TNF-alpha also enhanced IFN-gamma dependent changes in cell morphology but did not induce cell death. CONCLUSION: IFN-gamma alters T84 cell epithelial properties and TNF-alpha can enhance these effects, perhaps due to IFN-gamma dependent increases in TNF receptor gene expression. Overall, these studies suggest that in IBD, TNF-alpha may have synergistic effects on IFN-gamma mediated alterations of epithelial cell function.

Apoptosis↗
PubMed2003

Antibiotics with a selective aerobic or anaerobic spectrum have different therapeutic activities in various regions of the colon in interleukin 10 gene deficient mice.

BACKGROUND AND AIMS: Multiple rodent models implicate resident intestinal bacteria in the pathogenesis of chronic immune mediated intestinal inflammation. Specific pathogen free (SPF) interleukin 10 gene deficient (IL-10(-/-)) mice develop colitis, which does not occur in the germ free (GF) state. We investigated whether broad or narrow spectrum antibiotics affect onset and progression of disease in various regions of IL-10(-/-) mice. METHODS: Metronidazole, ciprofloxacin, vancomycin-imipenem (50 mg/kg/day), or water (control) was administered orally before (prevention) or two weeks after (treatment) colonisation of GF IL-10(-/-) mice with SPF bacteria. After four weeks, colonic histology scores and cytokine production by colonic explants were determined. Caecal and colonic contents were collected for quantitative bacterial analysis. RESULTS: In the prevention study, all antibiotics decreased inflammation in the caecum and colon. However, in the treatment study, ciprofloxacin and vancomycin-imipenem decreased caecal inflammation, and reduced Escherichia coli and Enterococcus faecalis concentrations, whereas only vancomycin-imipenem lowered direct microscopic bacterial counts. In contrast, metronidazole and vancomycin-imipenem reduced colonic injury and eliminated anaerobic bacteria, including Bacteroides spp. CONCLUSIONS: Both narrow and broad spectrum antibiotics can prevent disease but treatment of established colitis is more selective. Ciprofloxacin is most effective in the treatment of caecal inflammation, metronidazole preferentially treats the colon, whereas vancomycin-imipenem definitively treats both regions. These results suggest that subsets of aerobic or anaerobic bacteria show regional differences in their capacity to mediate experimental colitis in IL-10(-/-) mice.

Animals↗
PubMed2003

Serum laminin and collagen IV in inflammatory bowel disease.

BACKGROUND: / AIMS: Laminin and collagen IV have been proposed as extracellular matrix serum markers. Because fibrosis is a major complication of inflammatory bowel disease, serum concentrations of laminin and collagen IV were measured in patients with ulcerative colitis (UC) and Crohn's disease (CD) and compared with inflammatory and healthy controls. METHODS: Laminin and collagen IV serum concentrations were measured in 170 patients with inflammatory bowel disease (86 UC and 84 CD), in 23 patients with other causes of intestinal inflammation, and in 80 matched healthy controls using commercially available enzyme linked immunosorbent assays. Laminin and collagen IV concentrations were correlated with disease activity, type, localisation, and treatment. RESULTS: Mean (SD) serum laminin concentrations were 281.0 (110.1) ng/ml in patients with UC, 275.6 (106.7) ng/ml in patients with CD, 192.0 (17.8) ng/ml in healthy controls, and 198.5 (32.5) ng/ml in inflammatory controls. Mean (SD) serum collagen IV concentrations were 72.8 (22.9) ng/ml in patients with UC, 71.0 (18.2) in patients with CD, 79.8 (12.2) ng/ml in healthy controls, and 88.9 (24.6) ng/ml in inflammatory controls. There was a significant difference among the four groups (p < 0.0001) for both markers. There was a strong correlation between serum laminin, but not collagen IV, and disease activity in both diseases. No significant association was found between these markers and disease localisation or disease type. CONCLUSIONS: Serum concentrations of laminin are increased, whereas serum concentrations of collagen IV are decreased, in patients with inflammatory bowel disease. They may be useful surrogate markers for sustained inflammation and tissue remodelling.

Adult↗
PubMed2003

Neurotensin stimulates IL-8 expression in human colonic epithelial cells through Rho GTPase-mediated NF-kappa B pathways.

Neurotensin (NT), a neuropeptide highly expressed in the gastrointestinal tract, participates in the pathophysiology of intestinal inflammation. We recently showed that NT stimulates interleukin-8 (IL-8) expression in NCM460 nontransformed human colonic epithelial cells via both mitogen-activating protein kinase (MAPK)- and NF-kappaB-dependent pathways. However, the molecular mechanism by which NT induces expression of proinflammatory cytokines such as IL-8 has not been investigated. In this study we show that inhibition of endogenous Rho family proteins (RhoA, Rac1, and Cdc42) by their respective dominant negative mutants inhibits NT-induced IL-8 protein production and promoter activity. Western blot experiments demonstrated that NT strongly activated RhoA, Rac1, and Cdc42. Overexpression of the dominant negative mutants of RhoA, Rac1, and Cdc42 significantly inhibited NT-induced NF-kappaB-dependent reporter gene expression and NF-kappaB DNA binding activity. NT also stimulated p38 MAPK phosphorylation, and overexpression of dominant negative mutants of RhoA, Rac1, and Cdc42 did not significantly alter p38 and ERK1/2 phosphorylation in response to NT. Together, our findings indicate that NT-stimulated IL-8 expression is mediated via a Rho-dependent NF-kappaB-mediated pathway.

Cell Line↗
PubMed2003

Regulation of IL-11 expression in intestinal myofibroblasts: role of c-Jun AP-1- and MAPK-dependent pathways.

IL-11 inhibits the activation of NF-kappaB and induces the Th2 polarization of CD4+ T cells. The clinical utility of IL-11 is being investigated in Crohn's disease. However, physiological secretion of IL-11 in the intestine remains unclear. In this study, we investigated IL-11 secretion in human intestinal subepithelial myofibroblasts (SEMFs). Intestinal SEMFs were isolated from the human colonic mucosa. IL-11 secretion and mRNA expression were determined by ELISA and Northern blot analysis. The activating protein (AP)-1-DNA binding activity was evaluated by EMSA. IL-11 secretion was induced by IL-1beta and transforming growth factor (TGF)-beta1. These were also observed at the mRNA level. The EMSAs demonstrated that both IL-1beta and TGF-beta1 induced AP-1 activation within 2 h after stimulation, and a blockade of AP-1 activation by the recombinant adenovirus containing a dominant negative c-Jun markedly reduced the IL-1beta- and TGF-beta1-induced IL-11 mRNA expression. IL-1beta and TGF-beta1 induced an activation of ERK p42/44 and p38 MAP kinases, and the MAP kinase inhibitors (SB-202190, PD-98059, and U-0216) significantly reduced the IL-1beta- and TGF-beta1-induced IL-11 secretion. The upregulation of IL-11 mRNA by IL-1beta- and TGF-beta1 was also mediated by a p38 MAP kinase-mediated mRNA stabilization. The combination of IL-1beta and TGF-beta1 additively enhanced IL-11 secretion. Intestinal SEMFs secreted IL-11 in response to IL-1beta- and TGF-beta1. Mucosal IL-11 secretion might be important as an anti-inflammatory response in the pathogenesis of intestinal inflammation.

Adenoviridae↗