UMLS:C0022104 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UMLS:C0022104 (irritable bowel syndrome)
8,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Throughout this symposium, recurrent themes were highlighted that may provide important clues to the pathogenesis of mucosal inflammation and IBD. First, the mucosal immune system is unique: Studies describing signaling paradigms in peripheral immunocytes should be re-explored in the gut where the rules that govern cell signaling may not be the same. Paradigms are a point of departure to characterize similarities and differences in mucosal immunity. A good example is a differential requirement for costimulation through CD2 in lamina propria T cells compared with peripheral T cells. Furthermore, a new definition of T-cell "costimulation" is beginning to emerge. Costimulatory molecules may function to overcome physical barriers by allowing cognate interactions between other molecules or by targeting signaling complexes to membrane microdomains. This concept also relates to another recurrent theme: Interactions between signaling pathways and the cytoskeleton are functionally important. Finally, we were introduced to the novel concept of metabolic parameters as a readout for signal transduction in the immune system. In the recent past, cell signaling has been viewed as a linear exercise, connecting a cell surface receptor to a series of intermediate molecules to a program of gene expression. However, signal transduction is in fact a three-dimensional exercise in cell biology. The future challenge, as pointed out in the keynote address, is to integrate reductionist models into reality and describe networks of signal transduction pathways in complex biosystems. "Threshold" responses were emphasized, with a small incremental increase or decrease in enzymatic activity leading to an on-off phenomenon referred to as a "molecular switch." In IBD, minute genetically determined differences in enzymatic activity may be critical. This point emphasizes the power of a genetic approach in IBD. Without strong genetic evidence, it is unlikely that fuctional assays will clarify the importance of small differences in enzymatic activity that may have dramatic biologic consequences. This symposium identified recently described signal transduction molecules that may be attractive therapeutic targets in IBD. Characterization of signaling molecules such as SLP-76, SLAM, SAP, and Fyb in the mucosal immune system will be an important area of future research. Ultimately, well-developed scientific hypotheses need to be tested in human beings. This paradigm was perhaps best illustrated by PPARgamma, where reductionist models and mouse experiments have recently lead to small trials suggesting proof of concept in human IBD. This meeting also emphasized a renewed interest in innate immunity in IBD and inflammation research. The role of enteric flora in initiating and perpetuating inflammation in animal models of IBD suggests at some level the importance of the innate immune response. The role of TLRs and bacterial interactions were discussed, as was NF-kappaB as the prominent transcription factor target of innate immune activation. Numerous bridges between innate and adaptive immunity were highlighted, including IL-10, IL-12, IL-18, and IFN-gamma. Their production during an innate immune response can profoundly affect functional T-cell responses in humans. In conclusion, the challenge of understanding signal transduction in IBD is one of integrating well-characterized inflammatory pathways into a complex biologic system that is inhabited by diverse cell types that communicate, and is characterized by interactions with a complex microbial environment. Making sense of this complexity is a daunting task that will require a multifactorial approach utilizing reductionist systems, mouse models, genetic studies, and ultimately human clinical trials.
...
PMID:Meeting summary: Signal transduction pathways in immune and inflammatory cells. November 30-December 3, 2000, Amelia Island, Florida, U.S.A. 1265 35

6-Mercaptopurine (6-MP) and its prodrug azathioprine (AZA) are well known for their lymphocytotoxic and bone marrow suppressive effects in the management of patients with leukemia. Although their immunosuppressive properties are mediated by the active AZA antimetabolite 6-thioguanine (6-TG), its mechanism of action is largely unknown. In IBD, a significant inverse correlation has been shown between erythrocyte 6-TG metabolite levels and disease activity, further supporting the proposed immunosuppressive role for 6-TG. Since leukocytes possess quantitatively different purine metabolic pathways compared to erythrocytes, this study aims to measure lymphocyte DNA 6-TG metabolites and correlate levels with the INF-gamma and IL-10 cytokine profile in patients with Crohn's disease (CD). Forty-six adult patients with CD, either naive (17) or on long-term (>4-month) AZA therapy (29), had erythrocyte and lymphocyte DNA 6-TG levels measured by reverse-phase HPLC under UV detection (6-TG, 340 nm). Lymphocyte DNA 6-TG was expressed as picomoles per milligram of DNA. Lymphocyte DNA 6-TG metabolite levels were correlated with INF-gamma and IL-10 cytokine profiles using the OptEIA kit (Pharmigen). Lymphocyte DNA 6-TG metabolite levels correlate with erythrocyte 6-TG levels (P < 0.03) but not total patient leukocyte levels. Erythrocyte 6-TG metabolite levels correlated (P < 0.01) inversely with INF-gamma but not IL-10 cytokine levels. This study suggests a preferential dampening of the TH1 response on exposure to 6-TG and a possible immunosuppressive mechanism of action for AZA. Future studies are needed to determine if cytokine profiles can be used to predict recalcitrant CD to AZA therapy.
...
PMID:Peripheral blood mononuclear cell DNA 6-thioguanine metabolite levels correlate with decreased interferon-gamma production in patients with Crohn's disease on AZA therapy. 1499 47

In the rich, developed parts of the world there has been a steady and simultaneous increase in at least three groups of disease: (1) allergies, (2) inflammatory bowel diseases (IBD; e.g. Crohn's disease and ulcerative colitis) and (3) autoimmunity (e.g. type 1 diabetes and multiple sclerosis). Because the medical world is so compartmentalised it was some time before the connection between these increases was noticed and understood. There is now evidence that the simultaneous increase in these diseases of immunodysregulation is at least partly attributable to malfunction of regulatory T cells (Treg). This paper provides an overview of relevant work in each of these fields of medicine (though with emphasis on the allergic disorders), and concludes that the increasing failure of Treg is a consequence of diminished exposure to certain micro-organisms that are "old friends", because of their continuous presence throughout mammalian evolution. These organisms, which include saprophytic mycobacteria, helminths and lactobacilli, are recognised by the innate immune system as harmless, and as adjuvants for Treg induction. Polymorphisms of components of the innate immune system such as TLR2 and NOD2 appear to define subsets of the population that will develop immunoregulatory disorders when living in the modern environment. A further role of the "old friends" and of the Treg that they induce might be to maintain the levels of regulatory IL-10 secreting macrophages and antigen-presenting cells, which are depleted in asthma and Crohn's disease. These concepts are leading to novel therapies based on harmless organisms or their components. Phase I/II clinical trials have yielded some statistically significant results, and phase II trials are in progress.
...
PMID:Mycobacteria and other environmental organisms as immunomodulators for immunoregulatory disorders. 1500 29

Products of arachidonic acid metabolism are important for mucosal homeostasis, because blockade of this pathway with an NSAID triggers rapid onset of severe colitis in the IL-10 knockout (IL-10(-/-)) model of IBD. Rag mice do not make T or B cells. This study determined whether reconstitution of Rag mice with T cells from IL-10(-/-) mice transferred NSAID colitis susceptibility. Rag mice were reconstituted by intraperitoneal injection with splenocytes from wild-type (WT) or IL-10(-/-) animals. Colitis was induced by using piroxicam and was graded histologically. Isolated lamina propria mononuclear cells (LPMC), lamina propria T cells, and LPMC depleted of T cells from reconstituted Rag mice were studied for cytokine production. Only animals reconstituted with IL-10(-/-) CD4(+) T cells and administered piroxicam developed severe colitis. LPMC from these colitic animals made IFN-gamma, whose production was dependent on T cells. Some IL-10 was produced but only from non-T cells. LPMC from the healthy Rag mice that were reconstituted with WT T cells and were piroxicam resistant made much more IL-10. This was mostly T cell dependent. In conclusion, only CD4(+) T cells from IL-10(-/-) animals leave Rag mice susceptible to NSAID-induced, Th1 colitis. Lamina propria T cells normally make large quantities of IL-10, suggesting that IL-10 from T cells may be protective.
...
PMID:CD4+ T cells from IL-10-deficient mice transfer susceptibility to NSAID-induced Rag colitis. 1524 67

Our understanding of the etiology and pathogenesis of IBD has improved extensively over the past years. At the center of the pathogenesis seems to be an excessive pro-inflammatory immune reaction towards normal intestinal flora. The different factors involved in this concept will form the focus of this review. The initial phase of antigen processing and presentation can be influenced by either modulation of the intestinal flora via antibiotics or probiotics or by direct stimulation of macrophages through GM-CSF treatment. Antigen recognition and activation of T-cells can be down-regulated by immunosuppressives such as azathioprine, CsA or methotrexate thus building the basis for current treatment in IBD. The pro-inflammatory character of the immune reaction is defined by the predominance of certain T-cell subpopulations. By targeting cytokines the disbalance of these subpopulation should be reconstituted. Here we will focus first on preliminary clinical as well as experimental data for the pro-inflammatory mediators IL-12 and IL-18 as well as for the anti-inflammatory cytokine IL-10. Second, the clinical data for the TNFalpha antibody that has been proven to be efficacious in Crohn's disease and the associated risks will be discussed. Last, recent clinical and experimental data on targeting cell adhesion as well as intracellular signaling pathways will be presented. In summary, with regard to this review, treatments, which intervene as early as possible in the initiation of the pathological immune reaction and simultaneously have a favorable side-effect profile, must be the focus of future research.
...
PMID:Therapeutic approaches in inflammatory bowel disease based on the immunopathogenesis. 1563 10

Several twin studies and familial aggregation studies in IBS are consistent with either a genetic or a social learning hypothesis, and it is possible that both play a role. The prospect of identifying a genetic cause for IBS may be very important, because it raises the possibility of confirming that IBS isa disease entity, suggests new insight into the pathophysiology of the disorder, and provides new targets for drug development. Several candidate genetic markers including: those related to cytokines such as IL-10, TNF-alpha and TGF beta1; SERT-P; alpha-adrenergic receptors; and G proteins have been associated with certain aspects of IBS. Genetic polymorphisms,however, are common and may have no etiological or pathogenetic relevance. Searching for the genes in IBS is of potentially great relevance. Such studies may identify more specific phenotypes in IBS or potentially predict increased disease vulnerability, but it is unlikely that this strategy will lead to a diagnostic test, given the limited component of IBS that is likely to be genetically determined. Pharmaco genomic studies have potential to be important in the future. For this potential to be realized, it will be necessary to formally include genetic studies in trials of experimental drugs.This would enhance understanding of one of the roles of genetics for treating IBS.
...
PMID:Genetics and genotypes in irritable bowel syndrome: implications for diagnosis and treatment. 1586 37

The better understanding of the mechanisms of inflammatory bowel disease has driven our progress into the development of new biological therapies targeting specific molecules. Anti-TNF-alpha biologic compounds have shown great efficacy particularly in Crohn's disease. Infliximab (an IgG1 mouse/human chimeric monoclonal anti-TNF-alpha antibody fragment) is the most efficacious compound in induction and maintenance therapy of active and fistulizing Crohn's disease, being at present the only biological compound approved for therapy, but with the limit of the immunogenicity; CDP-571 (a humanized anti-TNF-alpha antibody) and CDP-870 (a PEGylated anti-TNF-alpha antibody) are less immunogenic, showed some efficacy in induction therapy in Crohn's disease but a rapid loss of response in maintenance therapy. Etanercept and onercept (soluble human recombinant TNF-alpha receptors fusion proteins) seem not to be efficacious in Crohn's disease demonstrating no class-effect for anti-TNF-alpha compounds. In preliminary study, adalimumab (an IgG1 humanized monoclonal anti-TNF-alpha antibody) offers good perspective of efficacy and safety also in infliximab-resistant or allergic patients. Inhibition of lymphocyte trafficking to the gut, through anti-adhesion molecules specific therapies (natalizumab, MLN-02, alicaforsen), has shown promising results: unfortunately, natalizumab, the most effective drug of this class, has recently been suspected to favour serious neurological complications. Other biologic therapies are under evaluation but at present seem to be less promising than infliximab; they consist of antiinflammatory cytokines, inhibitors of proinflammatory cytokines, hormones and growth factors: anti-IL12-antibody, interferon-alpha, interferon-beta, G-CSF, GM-CSF, EGF, growth hormone, anti-interferon-gamma, anti-IL-18, anti-IL-2-receptor and anti-CD3 antibodies. The evaluation of other biological drugs has been suspended for severe side effects as happened for anti-CD40L antibody causing thromboembolism and anti-CD4 antibody causing ly.mphopenia. Other compounds as IL-10 and IL-11 have been proven to be ineffective even if an oral formulation of IL-11 is under evaluation. Among the MAP kinases inhibitors BIRB-796 and RDP58 showed to be ineffective while CNI-1493 is under evaluation. The effort in identifying specific patients features predicting therapy response and the possible combination of different biological therapies represent undoubtedly a very promising perspective. Aim of this article is to review the biological compounds and their efficacy in IBD.
...
PMID:Biological therapies for inflammatory bowel disease: research drives clinics. 1684 27

Following the present concepts, the synthetic sphingosine analog of myriocin FTY720 alters migration and homing of lymphocytes via sphingosine 1-phosphate receptors. However, several studies indicate that the immunosuppressive properties of FTY720 may alternatively be due to tolerogenic activities via modulation of dendritic cell differentiation or based on direct effects on CD4(+)CD25(+) regulatory T cells (Treg). As Treg play an important role for the cure of inflammatory colitis, we used the Th1-mediated 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis model to address the therapeutic potential of FTY720 in vivo. A rectal enema of TNBS was given to BALB/c mice. FTY720 was administered i.p. from days 0 to 3 or 3 to 5. FTY720 substantially reduced all clinical, histopathologic, macroscopic, and microscopic parameters of colitis analyzed. The therapeutic effects of FTY720 were associated with a down-regulation of IL-12p70 and subsequent Th1 cytokines. Importantly, FTY720 treatment resulted in a prominent up-regulation of FoxP3, IL-10, TGFbeta, and CTLA4. Supporting the hypothesis that FTY720 directly affects functional activity of CD4(+)CD25(+) Treg, we measured a significant increase of CD25 and FoxP3 expression in isolated lamina propria CD4(+) T cells of FTY720-treated mice. The impact of FTY720 on Treg induction was further confirmed by concomitant in vivo blockade of CTLA4 or IL-10R which significantly abrogated its therapeutic activity. In conclusion, our data provide clear evidence that in addition to its well-established effects on migration FTY720 leads to a specific down-regulation of proinflammatory signals while simultaneously inducing functional activity of CD4(+)CD25(+) Treg. Thus, FTY720 may offer a promising new therapeutic strategy for the treatment of IBD.
...
PMID:FTY720 ameliorates Th1-mediated colitis in mice by directly affecting the functional activity of CD4+CD25+ regulatory T cells. 1727 53

In their review, the authors state that the very low incidence and prevalence of IBD in sub-Saharan Africa cannot be explained by genetic factors since in Black populations of the U.S.A. and U.K., the incidence of these diseases is approaching that of the white populations. Beside helminths whose intestinal infestation is frequent in sub-Saharan Africa, other micro-organisms such as atypical mycobacteria, lactobacilli, etc, might have been reduced in Western population. This is a new variant of the Hygiene hypothesis. After Rook et al., these micro-organisms were acting as adjuvants for induction of T regulatory cells which, associated with antigen-presenting cells secrete IL-10 and TGF-beta, inhibiting the maturation of CD4 T cells to Th1 and Th2 effector cells, and consequently reducing the occurrence of Th1-mediated diseases like Crohn's disease and Th2-mediated diseases like ulcerative colitis. The effects of intestinal helminths on host immunity have been studied in Ethiopian Jews emigrated to Israel. Thorough studies before and after deworming have demonstrated that chronic helminth infestation provokes a state of chronic immune activation with anergy, reversible after deworming. Administration of ova of Trichuris suis, an helminth non pathogenic in man, has given encouraging results in the treatment o Crohn's disease and ulcerative colitis with a good safety record but long-term trials are needed since the potentially harmful effects of helminths on immunity.
...
PMID:Intestinal helminths: a clue explaining the low incidence of inflammatory bowel diseases in Subsaharan Africa? Potential benefits and hazards of helminth therapy. 1963 90

There is no ideal animal model for the study of human pathologies such as IBD or CRC. For the last decade, genetically engineered animal models have been incorporated to models induced by exogenous agents. Experimental models of IBD reproduce heterogeneous intestinal inflammatory conditions, as it occurs in the human being, whereas CRC models imitate those mutations found in man although with different phenotypic repercussions. In both cases, these experimental systems are influenced by genetics and the environment. Today, animal models represent valued, complex, and complete bioassays for the study of new therapeutic strategies in IBD (IL-10, anti-IL-12, probiotics) and protective agents in CRC (n-3 fatty acids, NSAIDS, and COX-2 inhibitors).
...
PMID:[In vivo experimental models of inflammatory bowel disease and colorectal cancer]. 1741 34

<< Previous 1 2 3 4 5 6 7 8 Next >>