Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0009319 (colitis)
 19,384 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In previous studies, we have shown that murine CD4+CD25+ regulatory T cells produce high levels of TGF-beta1 in a cell surface and/or secreted form, and blockade of such TGF-beta1 by anti-TGF-beta curtails the ability of these cells to suppress CD25- T cell proliferation and B cell Ig production in in vitro suppressor assays. In further support for the role of TGF-beta1 in suppression by CD4+CD25+ T cells, we show in this study that another TGF-beta1-blocking molecule, recombinant latency-associated peptide of TGF-beta1 (rLAP), also reverses suppression by mouse CD4+CD25+ T cells as well as their human counterparts, CD4+CD25(high) T cells. In addition, we show that CD25- T cells exposed to CD4+CD25+ T cells in vitro manifest activation of Smad-2 and induction of CD103, the latter a TGF-beta-inducible surface integrin. In further studies, we show that while CD4+CD25+ T cells from TGF-beta1-deficient mice can suppress CD25- T cell proliferation in vitro, these cells do not protect recipient mice from colitis in the SCID transfer model in vivo, and, in addition, CD4+LAP+, but not CD4+LAP- T cells from normal mice protect recipient mice from colitis in this model. Together, these studies demonstrate that TGF-beta1 produced by CD4+CD25+ T cells is involved in the suppressor activity of these cells, particularly in their ability to regulate intestinal inflammation.
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PMID:TGF-beta 1 plays an important role in the mechanism of CD4+CD25+ regulatory T cell activity in both humans and mice. 1470 53

CD4+ alpha beta T cell populations that develop in mice deficient in MHC class II (through 'knockout' of either the Aalpha, or the Abeta chain of the I-A(b) molecule) comprise a major 'single-positive' (SP) CD4+ CD8- subset (60-90%) and a minor 'double-positive' (DP) CD4+ CD8alpha beta+ subset (10-40%). Many DP T cells found in spleen, mesenteric lymph nodes (MLN) and colonic lamina propria (cLP) express CD25, CD103 and Foxp3. Adoptive transfer of SP but not DP T cells from Aalpha(-/-) or Abeta(-/-) B6 mice into congenic RAG(-/-) hosts induces colitis. Transfer of SP T cells repopulates the host with only SP T cells; transfer of DP T cells repopulates the host with DP and SP T cells. Anti-CD25 antibody treatment of mice transplanted with DP T cells induces severe, lethal colitis; anti-CD25 antibody treatment of mice transplanted with SP T cells further aggravates the course of severe colitis. Hence, regulatory CD25+ T cells within (or developing from) the DP T cell population of MHC class II-deficient mice control the colitogenic potential of CD25- CD4+ T cells.
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PMID:MHC class II-independent CD25+ CD4+ CD8alpha beta+ alpha beta T cells attenuate CD4+ T cell-induced transfer colitis. 1499

Peyer's patches (PP) are important inductive sites for the mucosal immune response. It is well known that lymphocytes that migrate into PP are mainly of T-cell lineage from thymus-derived cells (i.e. alphabetaTCR(high) cells). In this study, we further characterized the properties of PP lymphocytes in mice using a mouse model of colitis induced by dextran sulphate sodium (DSS). Although the major site of the inflammation induced by DSS is known to be the large intestine, the small intestine was also damaged. When mice developed DSS-induced colitis, CD3+CD8+B220+ gammadelta T cells increased in PP in the small intestine. These gammadelta T cells, which are not seen in the PP of normal mice, resembled intraepithelial lymphocytes (IEL) in the small intestine in terms of their expression of CD5, CD103 and Thy1.2. In addition, the Vgamma/delta repertoire of these gammadelta T cells was similar to that of gammadelta IEL. When DSS-treated mice were injected with IEL isolated from normal mice, IEL including gammadelta T cells preferentially migrated to PP, raising the possibility that B220+ T cells seen in PP of diseased mice may derive from IEL in the small intestine. Our present study suggests that PP might be able to accept T-cell lineages from intestinal IEL as well as from thymus-derived T cells.
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PMID:Multipotential acceptance of Peyer's patches in the intestine for both thymus-derived T cells and extrathymic T cells in mice. 1617

The integrin CD103 is highly expressed at mucosal sites, but its role in mucosal immune regulation remains poorly understood. We have analyzed the functional role of CD103 in intestinal immune regulation using the T cell transfer model of colitis. Our results show no mandatory role for CD103 expression on T cells for either the development or CD4+CD25+ regulatory T (T reg) cell-mediated control of colitis. However, wild-type CD4+CD25+ T cells were unable to prevent colitis in immune-deficient recipients lacking CD103, demonstrating a nonredundant functional role for CD103 on host cells in T reg cell-mediated intestinal immune regulation. Non-T cell expression of CD103 is restricted primarily to CD11c(high)MHC class II(high) dendritic cells (DCs). This DC population is present at a high frequency in the gut-associated lymphoid tissue and appears to mediate a distinct functional role. Thus, CD103+ DCs, but not their CD103- counterparts, promoted expression of the gut-homing receptor CCR9 on T cells. Conversely, CD103- DCs promoted the differentiation of IFN-gamma-producing T cells. Collectively, these data suggest that CD103+ and CD103- DCs represent functionally distinct subsets and that CD103 expression on DCs influences the balance between effector and regulatory T cell activity in the intestine.
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PMID:Essential role for CD103 in the T cell-mediated regulation of experimental colitis. 1621 86

Because of the wide variations in the clinical presentation of celiac disease and because treatment exists that is effective in most cases, screening of the general population for celiac disease has been considered. There is still no evidence that patients who have symptom-free celiac disease are at increased risk of small intestinal lymphoma or other complications. Prevention of osteoporosis seems to be the strongest indicator for widespread screening today [22]. The major cause of failure to respond to a gluten-free diet is continuing ingestion of gluten, but other underlying diseases must be considered. Many different drugs (eg, anti-tumor necrosis factor [TNF]-alpha) have been used in patients who have RCD [23]. Steroid treatment has been reported to be effective even in patients who have underlying early EATL. Histologic recovery in patients who have celiac disease usually takes several months but can take up to 1 year, even if the patient remains on a strict gluten-free diet. Some patients report celiac-related symptoms for months after a single gluten intake. The definitions for RCD in literature vary. The authors consider the definition give by Daum and colleagues [24] suitable. They defined true RCD as villous atrophy with crypt hyperplasia and increased IELs persisting for more than 12 months in spite of a strict gluten-free diet. If a patient is not responding well to a gluten-free diet, three considerations are necessary: (1) the initial diagnosis of celiac disease must be reassessed;(2) the patient should be sent to a dietician to check for errors in diet or compliance problems, because problems with the gluten-free diet are the most important cause for persisting symptoms; (3) other reasons for persisting symptoms (eg, pancreatic insufficiency, irritable bowel syndrome, bacterial overgrowth, lymphocytic colitis, collagenous colitis, ulcerative jejunitis, protein-losing enteropathy,T-cell lymphoma, fructose intolerance, cavitating lymphadenopathy, and tropical sprue) should be considered. Other causes for villous atrophy are Crohn's disease, collagenous sprue, and autoimmune enteropathy. Abdulkarim and colleagues [25] examined 55 patients who had a diagnosis of nonresponsive celiac disease. He found that 6 did not have celiac disease, and25 still had some gluten ingestion.Tursi and colleagues [26] reported 15 patients who had celiac disease with persisting symptoms. Because histology improved in all patients after several months, RCD was excluded. Of the 15 patients, 10 had small intestinal bacterial overgrowth, 2 showed lactose malabsorption causing the described symptoms, 1 had mistakenly taken an antibiotic containing gluten, and 1 patient each had Giardia lamblia and Ascaris lumbricoides. Thus, other entities must be considered in patients who have celiac disease and ongoing symptoms. In a follow-up clinical trial, 158 patients who had celiac disease underwent follow-up small intestine biopsies within 2 years after starting a gluten-free diet. Eleven patients (7.0%) with persisting (partial) villous atrophy were considered to have RCD; 5 of them developed EATL [27].RCD type I is characterized by normal expression of T-cell antigens and polyclonal TCR gene rearrangement.RCD type II is characterized by an abnormal IEL phenotype with the expression of intracytoplasmic CD3e, surface CD103, and the lack of classic surface T-cell markers such as CD8, CD4, and TCR-alpha/beta. This clonal IEL population can be considered crypt IEL [24]. RCD II has a poor prognosis, which is a problem for therapy. Clonal TCR gene rearrangements and loss of T-cell antigens such as CD8 and TCR-beta in IELs may indicate the development of an EATL in patients who have RCD. The markers for an overt EATL are a positive stool blood test, increased lactate dehydrogenase, or beta2-microglobulin [24]. If an overt lymphoma is suspected, upper and lower endoscopy, an ear, nose, and throat work-up, CT scan, capsule endoscopy, and possibly double-balloon enteroscopy should be performed. Most reports of the difficulties in treating patients who have true RCE are casereports. Turner and colleagues [28] reported on an induction of remission by useof the anti-TNF-alpha antibody infliximab and maintenance with prednisoloneand azathioprine. Olaussen and colleagues [29] and Mandal and colleagues [30]tried a nonimmunogenic elemental diet. Gillet and colleagues [31] reported successful treatment of a patient who hadRCD using anti-TNF-alpha antibodies (infliximab) for induction and azathioprinefor maintenance. Maurino and colleagues [32] studied seven consecutive patients diagnosed ashaving refractory sprue and no response to oral or parenteral steroids. Aftertreatment with azathioprine (2 mg/kg/d) and oral prednisone (1 mg/kg/d), fivepatients had a complete clinical remission. Two patients who did not respond totreatment at any time died. Goerres and colleagues [33] described 18 patients who had RCD, 10 of whomhad type I RCD, and 8 of whom had type II RCD. Treatment consisted ofazathioprine combined with prednisone for 1 year. Consistent with reports byother investigators, the response rates in the two groups differed. Eight of the10 patients who had type I RCD had a histologic response. Seven of the eightpatients who had type II RCD died, and six of the eight developed a lymphoma. At present there is no effective treatment for type II RCD.Fig. 3 presents a proposed algorithm for monitoring patients who have ce-liac disease.
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PMID:Monitoring nonresponsive patients who have celiac disease. 1687 29

The gastrointestinal (GI) tract is the main interface where the body encounters exogenous antigens. It is crucial that the local response here is tightly regulated to avoid an immune reaction against dietary antigens and commensal flora while still mounting an efficient defense against pathogens. Faults in establishing intestinal tolerance can lead to disease, inducing local and often also systemic inflammation. Studies in human as well as in animal models suggest a role for regulatory T cells (Tregs) in maintaining intestinal homeostasis. Transfer of Tregs can not only prevent the development of colitis in animal models but also cure established disease, acting both systemically and at the site of inflammation. In this review, we discuss the major regulatory pathways, including transforming growth factor-beta (TGF-beta), interleukin-10 (IL-10), and cytotoxic T-lymphocyte antigen-4 (CTLA-4), and their role in Treg-mediated control of systemic and mucosal responses. In addition, we give an overview of the known mechanisms of lymphocyte migration to the intestine and discuss how CD103 expression can influence the balance between regulatory and effector T cells. Further understanding of the factors that control the activity of Tregs in different immune compartments may facilitate the design of strategies to target regulation in a tissue-specific way.
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PMID:Regulatory T cells suppress systemic and mucosal immune activation to control intestinal inflammation. 1690 19

Regulatory T cells (T(reg)) play an important role in immune regulation. Their development in the thymus requires TCR activation and recognition of peptide-MHC, although the downstream signals controlling commitment to the lineage are unclear. To compare the requirements for positive selection and T(reg) development, we studied knockout and transgenic mice defective in Raf signaling and the ERK effector SRF accessory protein 1 (SAP-1), a member of the ternary complex factor family of Ets domain transcription factors. Although SAP-1 deficient mice display a severe defect in thymocyte positive selection, T(reg) development was unimpaired as assessed by expression of Foxp3 and the activation markers CD25, GITR, CTLA4, and CD103 in the CD4(+) cell population. In contrast, inhibition of Raf signaling by the interfering dominant negative Raf derivative reduced both Foxp3(+) and Foxp3(-) CD4(+) populations. In SAP-1-deficient CD4(+)CD25(+) T(reg) cells, TCR crosslinking efficiently induced ERK activation, but transcriptional induction of the immediate early gene Egr-1 was impaired. Nevertheless, neither deletion of SAP-1 nor expression of a dominant negative Raf derivative affected the ability of CD4(+)CD25(+) T(reg) cells to suppress CD4(+)CD25(-) cell proliferation in vitro. Finally the suppressive activity of CD4(+)CD25(+) T(reg) cells lacking SAP-1 in an in vivo colitis model was not significantly impaired. The signaling requirements for development of T(reg) cells in the thymus are thus distinct from those required for "conventional" T cell positive selection, and ERK signaling to SAP-1 is not required for the suppressive activity of T(reg) cells.
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PMID:Raf signaling but not the ERK effector SAP-1 is required for regulatory T cell development. 1798 74

Intestinal dendritic cells (DCs) have been shown to display specialized functions, including the ability to promote gut tropism to lymphocytes, to polarize noninflammatory responses, and to drive the differentiation of adaptive Foxp3(+) regulatory T (T(reg)) cells. However, very little is known about what drives the mucosal phenotype of DCs. Here, we present evidence that the local microenvironment, and in particular intestinal epithelial cells (ECs), drive the differentiation of T(reg)-cell-promoting DCs, which counteracts Th1 and Th17 development. EC-derived transforming growth factor-beta (TGF-beta) and retinoic acid (RA), but not thymic stromal lymphopoietin (TSLP), were found to be required for DC conversion. After EC contact, DCs upregulated CD103 and acquired a tolerogenic phenotype. EC-conditioned DCs were capable of inducing de novo T(reg) cells with gut-homing properties that when adoptively transferred, protected mice from experimental colitis. Thus, we have uncovered an essential mechanism in which EC control of DC function is required for tolerance induction.
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PMID:Intestinal epithelial cells promote colitis-protective regulatory T-cell differentiation through dendritic cell conditioning. 1938 33

Mesenteric lymph node (mLN) CD103 (alphaE integrin)(+) dendritic cells (DCs) induce regulatory T cells and gut tolerance. However, the function of intestinal CD103(-) DCs remains to be clarified. CD47 is the ligand of signal regulatory protein alpha (SIRPalpha) and promotes SIRPalpha(+) myeloid cell migration. We first show that mucosal CD103(-) DCs selectively express SIRPalpha and that their frequency was augmented in the lamina propria and mLNs of mice that developed Th17-biased colitis in response to trinitrobenzene sulfonic acid. In contrast, the percentage of SIRPalpha(+)CD103(-) DCs and Th17 responses were decreased in CD47-deficient (CD47 knockout [KO]) mice, which remained protected from colitis. We next demonstrate that transferring wild-type (WT), but not CD47 KO, SIRPalpha(+)CD103(-) DCs in CD47 KO mice elicited severe Th17-associated wasting disease. CD47 expression was required on the SIRPalpha(+)CD103(-) DCs for efficient trafficking to mLNs in vivo, whereas it was dispensable on both DCs and T cells for Th17 polarization in vitro. Finally, administration of a CD47-Fc molecule resulted in reduced SIRPalpha(+)CD103(-) DC-mediated Th17 responses and the protection of WT mice from colitis. We thus propose SIRPalpha(+)CD103(-) DCs as a pathogenic DC subset that drives Th17-biased responses and colitis, and the CD47-SIRPalpha axis as a potential therapeutic target for inflammatory bowel disease.
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PMID:A role for CD47 in the development of experimental colitis mediated by SIRPalpha+CD103- dendritic cells. 1970 89

The intestinal immune system discriminates between tolerance toward the commensal microflora and robust responses to pathogens. Maintenance of this critical balance is attributed to mucosal dendritic cells (DCs) residing in organized lymphoid tissue and dispersed in the subepithelial lamina propria. In situ parameters of lamina propria DCs (lpDCs) remain poorly understood. Here, we combined conditional cell ablation and precursor-mediated in vivo reconstitution to establish that lpDC subsets have distinct origins and functions. CD103(+) CX(3)CR1(-) lpDCs arose from macrophage-DC precursors (MDPs) via DC-committed intermediates (pre-cDCs) through a Flt3L growth-factor-mediated pathway. CD11b(+) CD14(+) CX(3)CR1(+) lpDCs were derived from grafted Ly6C(hi) but not Ly6C(lo) monocytes under the control of GM-CSF. Mice reconstituted exclusively with CX(3)CR1(+) lpDCs when challenged in an innate colitis model developed severe intestinal inflammation that was driven by graft-derived TNF-alpha-secreting CX(3)CR1(+) lpDCs. Our results highlight the critical importance of the lpDC subset balance for robust gut homeostasis.
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PMID:Intestinal lamina propria dendritic cell subsets have different origin and functions. 1976 89


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