Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0010346 (Crohn's disease)
 21,615 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neutralization of TNF-alpha in humans with rheumatoid arthritis or Crohn's disease has been associated with the development of humoral autoimmunity. To determine the effect of TNF-alpha neutralization on cell-mediated and humoral-mediated responses, we administered anti-TNF-alpha mAb to mice undergoing acute graft-vs-host disease (GVHD) using the parent-into-F(1) model. In vivo neutralization of TNF-alpha blocked the lymphocytopenic features characteristic of acute GVHD and induced a lupus-like chronic GVHD phenotype (lymphoproliferation and autoantibody production). These effects resulted from complete inhibition of detectable antihost CTL activity and required the presence of anti-TNF-alpha mAb for the first 4 days after parental cell transfer, indicating that TNF-alpha plays a critical role in the induction of CTL. Moreover, an in vivo blockade of TNF-alpha preferentially inhibited the production of IFN-gamma and blocked IFN-gamma-dependent up-regulation of Fas; however, cytokines such as IL-10, IL-6, or IL-4 were not inhibited. These results suggest that a therapeutic TNF-alpha blockade may promote humoral autoimmunity by selectively inhibiting the induction of a CTL response that would normally suppress autoreactive B cells.
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PMID:In vivo neutralization of TNF-alpha promotes humoral autoimmunity by preventing the induction of CTL. 1173 98

IL-18 and IL-18 binding protein (IL-18BP) are two newly described opponents in the cytokine network. Local concentrations of these two players may determine biological functions of IL-18 in the context of inflammation, infection, and cancer. As IL-18 appears to be involved in the pathogenesis of Crohn's disease and may modulate tumor growth, we investigated the IL-18/IL-18BPa system in the human colon carcinoma/epithelial cell line DLD-1. In this study, we report that IFN-gamma induces expression and release of IL-18BPa from DLD-1 cells. mRNA induction and secretion of IL-18BPa immunoreactivity were associated with an activity that significantly impaired release of IFN-gamma by IL-12/IL-18-stimulated PBMC. Inducibility of IL-18BPa by IFN-gamma was also observed in LoVo, Caco-2, and HCT116 human colon carcinoma cell lines and in the human keratinocyte cell line HaCaT. Induction of IL-18BPa in colon carcinoma/epithelial cell lines was suppressed by coincubation with sodium butyrate. IFN-gamma-mediated IL-18BPa and its suppression by sodium butyrate were confirmed in organ cultures of intestinal colonic biopsy specimens. In contrast, sodium butyrate did not modulate expression of IL-18. The present data suggest that IFN-gamma may limit biological functions of IL-18 at sites of colonic immune activation by inducing IL-18BPa production. Down-regulation of IL-18BPa by sodium butyrate suggests that reinforcement of local IL-18 activity may contribute to actions of this short-chain fatty acid in the colonic microenvironment.
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PMID:Expression and release of IL-18 binding protein in response to IFN-gamma. 1173 24

Recent studies have shown that IL-18, a pleiotropic cytokine that augments IFN-gamma production, is produced by intestinal epithelial cells and lamina propria cells from patients with Crohn's disease. In this study, we show that IL-18 is strongly expressed by intestinal epithelial cells in a murine model of Crohn's disease induced by transfer of CD62L+ CD4+ T cells into SCID mice. To specifically down-regulate IL-18 expression in this model, we constructed an E1/E3-deleted adenovirus expressing IL-18 antisense mRNA, denoted Ad-asIL-18, and demonstrated the capacity of such a vector to down-regulate IL-18 expression in colon-derived DLD-1 cells and RAW264.7 macrophages. Local administration of the Ad-asIL-18 vector to SCID mice with established colitis led to transduction of epithelial cells and caused a significant suppression of colitis activity, as assessed by a newly developed endoscopic analysis system for colitis. Furthermore, treatment with Ad-asIL-18 induced a significant suppression of histologic colitis activity and caused suppression of mucosal IFN-gamma production, whereas IFN-gamma production by spleen T cells was unaffected. Taken together, these data indicate an important role for IL-18 in the effector phase of a T cell-dependent murine model of colitis and suggest that strategies targeting IL-18 expression may be used for the treatment of patients with Crohn's disease.
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PMID:Treatment of T cell-dependent experimental colitis in SCID mice by local administration of an adenovirus expressing IL-18 antisense mRNA. 1175 87

We investigated whether a lack of IL-10 production or responsiveness could be involved in Crohn's disease pathogenesis. Lamina propria mononuclear cells, isolated from the ilea of Crohn's disease patients (n = 16) and controls (n = 13), were activated with anti-CD3 mAb in the presence of CD80 transfectants or LPS +/- IFN-gamma. No evidence for deficient IL-10 production by either T cells or macrophages in Crohn's disease was found. However, the efficacy of rhIL-10 to down-regulate IFN-gamma and especially TNF production in cell cultures from the involved tissues of Crohn's disease patients was poor, and the use of an anti-IL-10R mAb even provided evidence for proinflammatory effects of IL-10. This lack of IL-10 effect possibly results from IL-12 activity. We conclude that IL-10 exhibits poor anti- and even potential proinflammatory effects on ileal Crohn's disease lamina propria. These data might explain the lack of therapeutic efficacy when IL-10 is given to Crohn's disease patients.
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PMID:Decreased lamina propria effector cell responsiveness to interleukin-10 in ileal Crohn's disease. 1178 Oct 69

MICA are distant homologs of MHC class I molecules expressed in the normal intestinal epithelium. They are ligands of the NKG2D activating receptor expressed on most gammadelta T cells, CD8+ alphabeta T cells, and natural killer cells and therefore play a critical role in innate immune responses. We investigated MICA cell-surface expression on infection of epithelial cell lines by enteric bacteria and show here that MICA expression can be markedly increased by bacteria of the diffusely adherent Escherichia coli diarrheagenic group. This effect is mediated by the specific interaction between bacterial adhesin AfaE and its cellular receptor, CD55, or decay-accelerating factor. It is extremely rapid after AfaE binding, consistent with a stress-induced signal. MICA induction on epithelial cells triggered IFN-gamma release by the NKG2D expressing natural killer cell line NKL. This host-bacteria interaction pathway could play a role in the pathogenesis of inflammatory bowel disease, a condition that implicates a bacterial trigger in genetically susceptible individuals. This was supported by the increased MICA expression at the surface of epithelial cells in colonic biopsies from Crohn's disease-affected patients compared with controls.
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PMID:Binding of Escherichia coli adhesin AfaE to CD55 triggers cell-surface expression of the MHC class I-related molecule MICA. 1188 Jun 13

The balance between pro and antiinflammatory cytokines secreted by T cells regulates both the initiation and perpetuation of inflammatory bowel diseases (IBD). In particular, the balance between interferon (IFN)-gamma/interleukin (IL)-4 and transforming growth factor (TGF)-beta activity controls chronic intestinal inflammation. However, the molecular pathways that evoke these responses are not well understood. Here, we describe a critical role for the transcription factor T-bet in controlling the mucosal cytokine balance and clinical disease. We studied the expression and function of T-bet in patients with IBD and in mucosal T cells in various T helper (Th)1- and Th2-mediated animal models of chronic intestinal inflammation by taking advantage of mice that lack T-bet and retroviral transduction techniques, respectively. Whereas retroviral transduction of T-bet in CD62L(+) CD4(+) T cells exacerbated colitis in reconstituted SCID mice, T-bet-deficient T cells failed to induce colitis in adoptive transfer experiments suggesting that overexpression of T-bet is essential and sufficient to promote Th1-mediated colitis in vivo. Furthermore, T-bet-deficient CD62L(-) CD4(+) T cells showed enhanced protective functions in Th1-mediated colitis and exhibited increased TGF-beta signaling suggesting that a T-bet driven pathway of T cell activation controls the intestinal balance between IFN-gamma/IL-4 and TGF-beta responses and the development of chronic intestinal inflammation in T cell-mediated colitis. Furthermore, TGF-beta was found to suppress T-bet expression suggesting a reciprocal relationship between TGF-beta and T-bet in mucosal T cells. In summary, our data suggest a key regulatory role of T-bet in the pathogenesis of T cell-mediated colitis. Specific targeting of this pathway may be a promising novel approach for the treatment of patients with Crohn's disease and other autoimmune diseases mediated by Th1 T lymphocytes.
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PMID:The transcription factor T-bet regulates mucosal T cell activation in experimental colitis and Crohn's disease. 1199 18

To clarify the role of IL-15 at local sites, we engineered a transgenic (Tg) mouse (T3(b)-IL-15 Tg) to overexpress human IL-15 preferentially in intestinal epithelial cells by the use of T3(b)-promoter. Although IL-15 was expressed in the entire small intestine (SI) and large intestines of the Tg mice, localized inflammation developed in the proximal SI only. Histopathologic study revealed reduced villus length, marked infiltration of lymphocytes, and vacuolar degeneration of the villus epithelium, beginning at approximately 3-4 mo of age. The numbers of CD8(+) T cells, especially CD8alphabeta(+) T cells expressing NK1.1, were dramatically increased in the lamina propria of the involved SI. The severity of inflammation corresponded to increased numbers of CD8alphabeta(+)NK1.1(+) T cells and levels of production of the Th1-type cytokines IFN-gamma and TNF-alpha. Locally overexpressed IL-15 was accompanied by increased resistance of CD8alphabeta(+) NK1.1(+) T cells to activation-induced cell death. Our results suggest that chronic inflammation in the SI in this murine model is mediated by dysregulation of epithelial cell-derived IL-15. The model may contribute to understanding the role of CD8(+) T cells in human Crohn's disease involving the SI.
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PMID:IL-15-dependent activation-induced cell death-resistant Th1 type CD8 alpha beta+NK1.1+ T cells for the development of small intestinal inflammation. 1207 77

The roles of various cytokines in early-phase mycobacterial infection were investigated utilizing murine tuberculosis models. Among them, IFN-gamma and TNF-alpha are very important in protective immunity against mycobacterial infection. This finding is closely associated with human tuberculosis. It is reported that persons with IFN-gamma receptor 1 deficiency and patients with rheumatoid arthritis and Crohn's disease are susceptible to Mycobacterium tuberculosis. It is expected that a novel immunotherapy and a diagnostic method of tuberculosis are developed by clarifying roles of various cytokines immunologically in early-phase mycobacterial infection.
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PMID:Study on the roles of cytokines involved in mycobacterial infection. 1223 51

Resident intestinal bacteria likely play an important role in the pathogenesis of Crohn's disease through their interaction with the gut immune system. SAMP1/YitFc mice spontaneously develop chronic, discontinuous, transmural ileitis with many features similar to Crohn's disease. The aim of this study was to determine the effects and elucidate the mechanisms of action of antibiotic treatment in the SAMP1/YitFc mouse model of ileitis. Mice were treated orally with ciprofloxacin and metronidazole before the development of ileitis (prevention protocol) or after ileitis was fully established (treatment protocol). Terminal ilea were harvested for histological scoring, and lamina propria and mesenteric lymph node cells were isolated for analysis of activation markers and cytokine production. Antibiotic therapy significantly decreased the severity of ileitis both in the prevention (40% reduction, p < 0.05) and the treatment (25% reduction, p < 0.01) protocols, compared with untreated, control mice. These effects were associated with a decreased percentage of CD4(+)/CD45RB(high) lymphocytes in mesenteric lymph nodes of antibiotic-treated mice, as well as decreased production of IFN-gamma (prevention: 0.53 +/- 0.21 vs 1.84 +/- 0.04 ng/ml, p < 0.05; treatment: 8.4 +/- 0.4 vs 12.4 +/- 0.7 ng/ml, p < 0.005) and TNF (prevention: 61.5 +/- 13 vs 134 +/- 19 pg/ml, p < 0.01; treatment: 333.5 +/- 11 vs 496 +/- 20 pg/ml, p < 0.001). The number of activated lamina propria lymphocytes was also reduced after antibiotic treatment. In conclusion, antibiotic therapy significantly ameliorates the severity of ileitis in SAMP1/YitFc mice by a mechanism involving down-regulation of activated gut lymphocytes and inhibition of intestinal Th1 cytokine production.
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PMID:Down-regulation of intestinal lymphocyte activation and Th1 cytokine production by antibiotic therapy in a murine model of Crohn's disease. 1239 Dec 51

Crohn's disease results from dysregulated T helper (Th)1-type mucosal inflammation. Crohn's disease is rare in tropical countries but prevalent in developed countries with temperate climates, in which its incidence rose after 1940. In contrast, exposure to helminthic parasites is common in tropical countries but is rare in developed countries. Helminthic parasites induce immunomodulatory T cell responses in the host. We hypothesize that immunomodulatory responses due to helminths may attenuate excessive Th1-type inflammation. To test that hypothesis, mice were exposed to eggs of the helminth Schistosoma mansoni and then challenged rectally with trinitrobenzesulfonic acid (TNBS) to induce colitis. Schistosome egg exposure attenuated TNBS colitis and protected mice from lethal inflammation. Schistosome egg exposure diminished IFN-gamma and enhanced IL-4 production from alphaCD3-stimulated spleen and mesenteric lymph node cells of TNBS-treated mice. Schistosome egg exposure decreased colonic IFN-gamma but increased IL-10 mRNA expression in TNBS-treated mice. Intact signal transducer and activator of transcription 6 was required for attenuation of colitis. Exposure to helminths can decrease murine colonic inflammation.
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PMID:Exposure to schistosome eggs protects mice from TNBS-induced colitis. 1243 3


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