A new model of chronic colitis in SCID mice induced by adoptive transfer of CD62L+ CD4+ T cells: insights into the regulatory role of interleukin-6 on apoptosis.
<i>Objective:</i> The proinflammatory cytokine interleukin (IL)-6 is involved in various chronic inflammatory processes. IL-6 is a predominant cytokine produced by lamina propria T cells in Crohn’s disease and experimental colitis. This study was designed to examine the effect of a neutralizing IL-6-receptor (IL-6R) antibody on the programmed cell death of mucosal T cells in the CD62L+ CD4+ SCID transfer model of chronic experimental colitis in mice and to gain more insight into the pathogenesis of this transfer colitis model. <i>Methods:</i> For adoptive transfer, we isolated CD62L+ CD4+ double-positive T cells from wild-type BALB/c mice followed by intraperitoneal …
Azathioprine suppresses ezrin-radixin-moesin-dependent T cell-APC conjugation through inhibition of Vav guanosine exchange activity on rac proteins
Abstract We have shown recently that the azathioprine metabolite 6-Thio-GTP causes immunosuppression by blockade of GTPase activation in T lymphocytes. In the present study, we describe a new molecular mechanism by which 6-Thio-GTP blocks GTPase activation. Although 6-Thio-GTP could bind to various small GTPases, it specifically blocked activation of Rac1 and Rac2 but not of closely related Rho family members such as Cdc42 and RhoA in primary T cells upon stimulation with αCD28 or fibronectin. Binding of 6-Thio-GTP to Rac1 did not suppress Rac effector coupling directly but blocked Vav1 exchange activity upon 6-Thio-GTP hydrolysis, suggesting that 6-Thio-GTP loading leads to accumulation of…
Cutting Edge: IL-23 Cross-Regulates IL-12 Production in T Cell-Dependent Experimental Colitis
Abstract Although IL-12 and IL-23 share the common p40 subunit, IL-23, rather than IL-12, seems to drive the pathogenesis of experimental autoimmune encephalomyelitis and arthritis, because IL-23/p19 knockout mice are protected from disease. In contrast, we describe in this study that newly created LacZ knockin mice deficient for IL-23 p19 were highly susceptible for the development of experimental T cell-mediated TNBS colitis and showed even more severe colitis than wild-type mice by endoscopic and histologic criteria. Subsequent studies revealed that dendritic cells from p19-deficient mice produce elevated levels of IL-12, and that IL-23 down-regulates IL-12 expression upon TLR ligation. …
Programming of Intestinal Epithelial Differentiation by IL-33 Derived from Pericryptal Fibroblasts in Response to Systemic Infection.
SummaryThe intestinal epithelium constitutes an efficient barrier against the microbial flora. Here, we demonstrate an unexpected function of IL-33 as a regulator of epithelial barrier functions. Mice lacking IL-33 showed decreased Paneth cell numbers and lethal systemic infection in response to Salmonella typhimurium. IL-33 was produced upon microbial challenge by a distinct population of pericryptal fibroblasts neighboring the intestinal stem cell niche. IL-33 programmed the differentiation of epithelial progenitors toward secretory IEC including Paneth and goblet cells. Finally, IL-33 suppressed Notch signaling in epithelial cells and induced expression of transcription factors governing…
Animal models of intestinal inflammation: new insights into the molecular pathogenesis and immunotherapy of inflammatory bowel disease
Inflammatory bowel diseases (IBDs) in humans are complex chronic inflammatory disorders of largely unknown cause. Several mouse models that in some respects resemble human IBDs have recently been developed and have provided new insights into immunoregulatory processes in the gut. Both genetic and environmental factors have been shown to be involved in chronic intestinal inflammation. In most of the models CD4+ T lymphocytes have been identified as central mediators of inflammation. Inappropriate activation of T(H)1-dominated cytokine pathways upon contact with luminal bacterial antigens and lack of tolerance appear to be crucial for intestinal pathology. We present a brief overview of impor…
Regulation of IL-12 p40 Promoter Activity in Primary Human Monocytes: Roles of NF-κB, CCAAT/Enhancer-Binding Protein β, and PU.1 and Identification of a Novel Repressor Element (GA-12) That Responds to IL-4 and Prostaglandin E2
Abstract Appropriate regulation of IL-12 expression is critical for cell-mediated immune responses. In the present study, we have analyzed the regulation of IL-12 p40 promoter activity in primary human monocytes in vivo. Accordingly, we analyzed the p40 promoter by in vivo footprinting in resting and activated primary human blood CD14+ monocytes. Interestingly, footprints at binding sites for trans-activating proteins such as C/EBP, NF-κB, and ETS were only found upon stimulation with LPS and IFN-γ. In contrast, a footprint over a purine-rich sequence at −155, termed GA-12 (GATA sequence in the IL-12 promoter), was observed in resting, but not activated, cells. Further characterization of t…
Wheat Consumption Aggravates Colitis in Mice via Amylase Trypsin Inhibitor–mediated Dysbiosis
Background & Aims Wheat has become the world's major staple and its consumption correlates with prevalence of noncommunicable disorders such as inflammatory bowel diseases. Amylase trypsin inhibitors (ATIs), a component of wheat, activate the intestine's innate immune response via toll-like receptor 4 (TLR4). We investigated the effects of wheat and ATIs on severity of colitis and fecal microbiota in mice. Methods C57BL/6 wild-type and Tlr4–/– mice were fed wheat- or ATI-containing diets or a wheat-free (control) diet and then given dextran sodium sulfate to induce colitis; we also studied Il10–/– mice, which develop spontaneous colitis. Changes in fecal bacteria were assessed by taxa-speci…
Targeting of the transcription factor STAT4 by antisense phosphorothioate oligonucleotides suppresses collagen-induced arthritis
Abstract The transcription factor STAT4 mediates signals of various proinflammatory cytokines, such as IL-12, IL-15, and IL-23, that initiate and stabilize Th1 cytokine production. Although Th1 cytokine production has been suggested to play a major pathogenic role in rheumatoid arthritis, the role of STAT4 in this disease is poorly understood. In this study, we demonstrate a key functional role of STAT4 in murine collagen-induced arthritis (CIA). In initial studies we found that STAT4 expression is strongly induced in CD4+ T cells and to a lesser extent in CD11b+ APCs during CIA. To analyze the role of STAT4 for arthritis manifestation, we next investigated the outcome of interfering with S…
Assessment of Tumor Development and Wound Healing Using Endoscopic Techniques in Mice
Mouse models of intestinal inflammation and colon cancer are valuable tools to gain insights into the pathogenesis of the corresponding human diseases. Recently, in vivo mouse endoscopy has been developed, allowing not only the high-resolution monitoring and scoring of experimental disease development, but also enables the investigator to perform manipulations, including local injection of reagents or the taking of biopsies for molecular and histopathologic analyses. Chromoendoscopic staining with methylene blue enables visualization of the crypt structure and allows discrimination between inflammatory and neoplastic changes. The development of endoscopic techniques in live mice opened new …
RORgamma-expressing Th17 cells induce murine chronic intestinal inflammation via redundant effects of IL-17A and IL-17F.
Background and Aims IL-17–producing CD4 + T-helper cells (Th17) contribute to chronic autoimmune inflammation in the brain, and levels of Th17-derived cytokines increase in patients with colitis, suggesting a role in pathogenesis. We analyzed the roles of Th17 cells and the transcription factor retinoic acid receptor-related organ receptor (ROR)γ, which regulates Th17 differentiation, in chronic intestinal inflammation. Methods Using an adoptive transfer model of colitis, we compared the colitogenic potential of wild-type, interleukin-17A (IL-17A)–, IL-17F–, IL-22–, and RORγ-deficient CD4 + CD25 − T cells in RAG1-null mice. Results Adoptive transfer of IL-17A–, IL-17F–, or IL-22–deficient T…
IL-27 controls the development of inducible regulatory T cells and Th17 cells via differential effects on STAT1
IL-27 is an IL-12-related cytokine frequently present at sites of inflammation that can promote both anti- and pro-inflammatory immune responses. Here, we have analyzed the mechanisms how IL-27 may drive such divergent immune responses. While IL-27 suppressed the development of proinflammatory Th17 cells, a novel role for this cytokine in inhibiting the development of anti-inflammatory, inducible regulatory T cells (iTreg) was identified. In fact, IL-27 suppressed the development of adaptive, TGF-beta-induced Forkhead box transcription factor p3-positive (Foxp3(+)) Treg. Whereas the blockade of Th17 development was dependent on the transcription factor STAT1, the suppression of iTreg develo…
Interleukin-33-Dependent Innate Lymphoid Cells Mediate Hepatic Fibrosis
SummaryLiver fibrosis is a consequence of chronic liver diseases and thus a major cause of mortality and morbidity. Clinical evidence and animal studies suggest that local tissue homeostasis is disturbed due to immunological responses to chronic hepatocellular stress. Poorly defined stress-associated inflammatory networks are thought to mediate gradual accumulation of extracellular-matrix components, ultimately leading to fibrosis and liver failure. Here we have reported that hepatic expression of interleukin-33 (IL-33) was both required and sufficient for severe hepatic fibrosis in vivo. We have demonstrated that IL-33’s profibrotic effects related to activation and expansion of liver resi…
Finding Possible Weakness in the Runoff Simulation Experiments to Assess Rill Erosion Changes without Non-Intermittent Surveying Capabilities
The Terrestrial Photogrammetry Scanner (TEPHOS) offers the possibility to precisely monitor linear erosion features using the Structure from Motion (SfM) technique. This is a static, multi-camera array and dynamically moves the digital videoframe camera designed to obtain 3-D models of rills before and after the runoff experiments. The main goals were to (1) obtain better insight into the rills
Chronic intestinal inflammation in mice expressing viral Flip in epithelial cells
Viruses are present in the intestinal microflora and are currently discussed as a potential causative mechanism for the development of inflammatory bowel disease. A number of viruses, such as Human Herpesvirus-8, express homologs to cellular FLIPs, which are major contributors for the regulation of epithelial cell death. In this study we analyzed the consequences of constitutive expression of HHV8-viral FLIP in intestinal epithelial cells (IECs) in mice. Surprisingly, expression of vFlip disrupts tissue homeostasis and induces severe intestinal inflammation. Moreover vFlip(IEC-tg) mice showed reduced Paneth cell numbers, associated with excessive necrotic cell death. On a molecular level vF…
The transcription factor IFN regulatory factor–4 controls experimental colitis in mice via T cell–derived IL-6
The proinflammatory cytokine IL-6 seems to have an important role in the intestinal inflammation that characterizes inflammatory bowel diseases (IBDs) such as Crohn disease and ulcerative colitis. However, little is known about the molecular mechanisms regulating IL-6 production in IBD. Here, we assessed the role of the transcriptional regulator IFN regulatory factor-4 (IRF4) in this process. Patients with either Crohn disease or ulcerative colitis exhibited increased IRF4 expression in lamina propria CD3+ T cells as compared with control patients. Consistent with IRF4 having a regulatory function in T cells, in a mouse model of IBD whereby colitis is induced in RAG-deficient mice by transp…
IRF4 regulates IL-17A promoter activity and controls RORγt-dependent Th17 colitis in vivo
The transcription factor IRF4 is involved in several T-cell-dependent chronic inflammatory diseases. To elucidate the mechanisms for pathological cytokine production in colitis, we addressed the role of the IRF transcription factors in human inflammatory bowel disease (IBD) and experimental colitis.IRF levels and cytokine production in IBD patients were studied as well as the effects of IRF4 deficiency in experimental colitis.In contrast to IRF1, IRF5, and IRF8, IRF4 expression in IBD was augmented in the presence of active inflammation. Furthermore, IRF4 levels significantly correlated with IL-6 and IL-17 mRNA expression and to a lesser extent with IL-22 mRNA expression in IBD. To further …
Perforin deficiency attenuates inflammation and tumor growth in colitis-associated cancer
Background: Patients with inflammatory bowel disease (IBD) have a markedly increased risk to develop colon cancer, but there are only limited data about the host antitumor response in such colitis-associated cancer. In the present study we aimed at assessing the role of perforin-dependent effector mechanisms in the immune response in a murine model of colitis-associated colon cancer. Methods: Wildtype and perforin-deficient mice were analyzed in a mouse model of colitis-associated colon cancer using azoxymethane (AOM) and dextran sodium sulfate (DSS). Results: Tumors of wildtype mice showed infiltration of CD4+, CD8+ T cells, natural killer (NK) cells, high numbers of apoptotic cells, and e…
Treatment of T Cell-Dependent Experimental Colitis in SCID Mice by Local Administration of an Adenovirus Expressing IL-18 Antisense mRNA
Abstract Recent studies have shown that IL-18, a pleiotropic cytokine that augments IFN-γ 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 administrat…
Rac1-Regulated Endothelial Radiation Response Stimulates Extravasation and Metastasis That Can Be Blocked by HMG-CoA Reductase Inhibitors
Radiotherapy (RT) plays a key role in cancer treatment. Although the benefit of ionizing radiation (IR) is well established, some findings raise the possibility that irradiation of the primary tumor not only triggers a killing response but also increases the metastatic potential of surviving tumor cells. Here we addressed the question of whether irradiation of normal cells outside of the primary tumor augments metastasis by stimulating the extravasation of circulating tumor cells. We show that IR exposure of human endothelial cells (EC), tumor cells (TC) or both increases TC-EC adhesion in vitro. IR-stimulated TC-EC adhesion was blocked by the HMG-CoA reductase inhibitor lovastatin. Glycyrr…
TGF-β Suppresses Tumor Progression in Colon Cancer by Inhibition of IL-6 trans-Signaling
Alterations of TGF-beta signaling have been described in colorectal cancer, although the molecular consequences are largely unknown. By using transgenic mice overexpressing TGF-beta or a dominant-negative TGF-betaRII, we demonstrate that TGF-beta signaling in tumor infiltrating T lymphocytes controls the growth of dysplastic epithelial cells in experimental colorectal cancer, as determined by histology and a novel system for high-resolution chromoendoscopy. At the molecular level, TGF-beta signaling in T cells regulated STAT-3 activation in tumor cells via IL-6. IL-6 signaling required tumor cell-derived soluble IL-6R rather than membrane bound IL-6R and suppression of such TGF-beta-depende…
Protection from lethal septic peritonitis by neutralizing the biological function of interleukin 27
The immune response to bacterial infections must be tightly controlled to guarantee pathogen elimination while preventing tissue damage by uncontrolled inflammation. Here, we demonstrate a key role of interleukin (IL)-27 in regulating this critical balance. IL-27 was rapidly induced during murine experimental peritonitis induced by cecal ligation and puncture (CLP). Furthermore, mice deficient for the EBI3 subunit of IL-27 were resistant to CLP-induced septic peritonitis as compared with wild-type controls, and this effect could be suppressed by injection of recombinant single-chain IL-27. EBI3−/− mice displayed significantly enhanced neutrophil migration and oxidative burst capacity during…
STAT3 links IL-22 signaling in intestinal epithelial cells to mucosal wound healing.
Signal transducer and activator of transcription (STAT) 3 is a pleiotropic transcription factor with important functions in cytokine signaling in a variety of tissues. However, the role of STAT3 in the intestinal epithelium is not well understood. We demonstrate that development of colonic inflammation is associated with the induction of STAT3 activity in intestinal epithelial cells (IECs). Studies in genetically engineered mice showed that epithelial STAT3 activation in dextran sodium sulfate colitis is dependent on interleukin (IL)-22 rather than IL-6. IL-22 was secreted by colonic CD11c+ cells in response to Toll-like receptor stimulation. Conditional knockout mice with an IEC-specific d…
EBV-Induced Gene 3 Transcription Is Induced by TLR Signaling in Primary Dendritic Cells via NF-κB Activation
Abstract The EBV-induced gene 3 (EBI3) is expressed in dendritic cells (DCs) and part of the cytokine IL-27 that controls Th cell development. However, its regulated expression in DCs is poorly understood. In the present study we demonstrate that EBI3 is expressed in splenic CD8−, CD8+, and plasmacytoid DC subsets and is induced upon TLR signaling. Cloning and functional analysis of the EBI3 promoter using in vivo footprinting and mutagenesis showed that stimulation via TLR2, TLR4, and TLR9 transactivated the promoter in primary DCs via NF-κB and Ets binding sites at −90 and −73 bp upstream of the transcriptional start site, respectively. Furthermore, we observed that NF-κB p50/p65 and PU.1…
The T-box transcription factor eomesodermin controls CD8 T cell activity and lymph node metastasis in human colorectal cancer.
An efficient cytolytic T cell function is essential for immune mediated rejection of colorectal cancer. However, the molecular mechanisms driving T cell mediated cancer rejection are still poorly understood. Here, we assessed the relevance of the T-box transcription factor eomesodermin in colorectal cancer. METHODS/ RESULTS: By analysing tissue probes from 88 different colorectal tumours, a significant (p0.02) inverse correlation between eomesodermin expression in colorectal cancers and the presence of lymph node metastases could be shown, whereas no such correlation was noted for the master transcription factor of regulatory T cells, FoxP3 and CD8 alpha expression. To evaluate whether this…
Externalized decondensed neutrophil chromatin occludes pancreatic ducts and drives pancreatitis
Ductal occlusion has been postulated to precipitate focal pancreatic inflammation, while the nature of the primary occluding agents has remained elusive. Neutrophils make use of histone citrullination by peptidyl arginine deiminase-4 (PADI4) in contact to particulate agents to extrude decondensed chromatin as neutrophil extracellular traps (NETs). In high cellular density, NETs form macroscopically visible aggregates. Here we show that such aggregates form inside pancreatic ducts in humans and mice occluding pancreatic ducts and thereby driving pancreatic inflammation. Experimental models indicate that PADI4 is critical for intraductal aggregate formation and that PADI4-deficiency abrogates…
VEGF receptor signaling links inflammation and tumorigenesis in colitis-associated cancer.
Inflammation drives expression of VEGFR2, which is expressed on and drives growth of tumor cells in colitis-associated cancer.
IL-6 Signaling Promotes Tumor Growth in Colorectal Cancer
Recent investigations support an important role for TGF-beta in the development of colorectal cancer. However, the molecular consequences of TGF-beta signaling in the colon remains incompletely understood. In a recent study in Immunity, we analyzed the role of TGF-beta in a murine model of colon cancer. Using transgenic mice overexpressing TGF-beta or a dominant negative TGF-beta receptor II under control of the CD2 minigene, we show that TGF-beta signaling in tumor infiltrating T lymphocytes regulates the growth of dysplastic colon epithelial cells, as determined by histology and a novel system for high resolution chromoendoscopy in vivo. At the molecular level, TGF-beta signaling in T cel…
IL-28A Is a Key Regulator of T-Cell–Mediated Liver Injury via the T-Box Transcription Factor T-Bet
Background & Aims: T-cell–mediated fulminant hepatitis is a potentially life-threatening event for which the underlying pathogenic mechanisms are not fully understood. Here, we demonstrate a key regulatory role of IL-28A in T-cell–mediated hepatitis. Methods: We cloned the murine IL-28A gene by reverse-transcription polymerase chain reaction, assessed the effects of recombinant IL-28A, and generated IL-28A–transgenic mice. Results: IL-28A induced TH1 cytokine production by CD4+ T lymphocytes in a T-bet–dependent manner and was up-regulated in a murine model of T-cell–mediated hepatitis upon Con A administration. In vivo, CD4+ T cells from newly created IL-28A–transgenic animals revealed an …
Interleukin 27 induces differentiation of neural C6-precursor cells into astrocytes.
Interleukin 6 (IL6)-type cytokines are major regulators of inflammation and thereby contribute to the neuropathology and pathophysiology associated with inflammation of the central nervous system (CNS). Furthermore, astrocyte development which is a key process in the development of the CNS is also controlled by cytokines of the IL6-family. Interleukin 27 (IL27) is a recently identified member of this family and has been implicated in the inhibition of TH17 T-cell-responses. Here we show that IL27 and the HHV8 encoded viral IL6 (vIL6) induce C6 glioma cells to differentiate into an astrocyte-like state. Cytokine stimulation led to STAT-factor phosphorylation and consequently to protein expre…
Blockade of interleukin 6 trans signaling suppresses T-cell resistance against apoptosis in chronic intestinal inflammation: Evidence in Crohn disease and experimental colitis in vivo
The pro-inflammatory cytokine interleukin (IL)-6 (refs. 1-5) can bind to cells lacking the IL-6 receptor (IL-6R) when it forms a complex with the soluble IL-6R (sIL-6R) (trans signaling). Here, we have assessed the contribution of this system to the increased resistance of mucosal T cells against apoptosis in Crohn disease (CD), a chronic inflammatory disease of the gastrointestinal tract. A neutralizing antibody against IL-6R suppressed established experimental colitis in various animal models of CD mediated by type 1 T-helper cells, by inducing apoptosis of lamina propria T cells. Similarly, specific neutralization of sIL-6R in vivo by a newly designed gp130-Fc fusion protein caused suppr…
In vivo imaging of colitis and colon cancer development in mice using high resolution chromoendoscopy
Background: Mouse models of colitis and cancer are indispensable for our understanding of the pathogenesis of these diseases. In the past, mice had to be sacrificed in order to analyse colitis activity and tumour development. We have developed a safe method for high resolution endoscopic monitoring of living mice. Methods: Mice developing colitis or colonic tumours were anaesthetised using avertine and repeatedly examined by endoscopy. A novel miniendoscope (1.9 mm outer diameter), denoted Coloview, was introduced via the anus and the colon was carefully insufflated with an air pump before analysis of the colonic mucosa. An extra working channel allowed the introduction of biopsy forceps or…
Disruption of T helper 2-immune responses in Epstein–Barr virus-induced gene 3-deficient mice
Epstein–Barr virus-induced gene 3 (EBI3) is a widely expressed IL-12p40-related protein that associates as a heterodimer with either IL-12p35 or an IL-12p35 homologue, p28, to create a new cytokine (IL-27). To define the function of EBI3in vivo, we generated knockout mice in which theebi3gene was targeted by homologous recombination. EBI3−/−mice exhibited normal numbers of both naive and mature CD4+and CD8+T cells and B cells, but markedly decreased numbers of invariant natural killer T cells (iNKT) as defined by staining with an α-galactosylceramide (αGalCer)-loaded CD1d-tetramer. iNKT cells from EBI3−/−mice exhibited decreased IL-4 and, to a lesser extent, IFN-γ production after αGalCer s…
Stepwise Regulation of TH1 Responses in Autoimmunity: Il-12-Related Cytokines and Their Receptors
Interleukin (IL)-12 is a key cytokine of cell-mediated immune responses. Until recently, IL-12 was believed to be unique in its ability to induce the differentiation of naive T cells toward the TH1 phenotype and in its pathogenic activity, as shown in various disease models including inflammatory bowel disease. However, recently, 2 additional cytokines closely related to IL-12, IL-23 and IL-27, were discovered. Until then, the role of IL-12 was overestimated because it was believed that the p40 subunit was unique to IL-12. The discovery that IL-12 shares p40 with IL-23 and that IL-23 but not IL-12 is essential in models of chronic inflammation and autoimmunity led to a model in which IL-12 …
Impaired Th1 responses in mice deficient in Epstein-Barr virus-induced gene 3 and challenged with physiological doses of Leishmania major.
Protection against Leishmania major is dependent on IL-12 release from L. major-infected dendritic cells (DC) that induce IFN-gamma-producing Th1/Tc1 cells. IL-27, a novel member of the IL-12 family, is a heterodimer composed of p28 and IL-12p40-related Epstein-Barr virus-induced gene 3 (EBI3), and was shown to be produced by DC. In this study, we utilized EBI3-deficient mice to investigate the role of IL-27 in leishmaniasis using physiological low-dose infections that mimic natural transmissions. Lesions in EBI3(-/-) mice were significantly larger between weeks 3 and 10 post infection, reaching up to approximately threefold increased lesion volumes compared to wild types. In parallel, derm…
Cutting Edge: A Key Pathogenic Role of IL-27 in T Cell- Mediated Hepatitis
Abstract The signals driving T cell activation in T cell-mediated fulminant hepatitis are not fully understood. In this study, we identify the cytokine IL-27p28/EBI3 as a major pathogenic factor in the ConA model of T cell-mediated hepatitis. We found an up-regulation of hepatic EBI3 and p28 expression and augmented levels of IL-27 in wild-type mice after ConA administration, suggesting a potential pathogenic role of this cytokine in ConA hepatitis. Consistently, IL-27 EBI3-deficient mice were almost completely protected from ConA-induced liver damage. Such protection was associated with reduced levels of IFN-γ and its signaling proteins pSTAT-1 and T-bet. Finally, in vivo blockade of IL-27…
Mouse models of inflammatory bowel disease.
Animal models of intestinal inflammation are indispensable for our understanding of the pathogenesis of Crohn disease and Ulcerative colitis, the idiopathic forms of inflammatory bowel disease in humans. The clinical appearance of human IBD is heterogeneous, a fact that is also reflected by the steadily increasing number of mouse strains displaying IBD like intestinal alterations. The analysis of these models together with genetic studies in humans greatly enhanced our insights into immunoregulatory processes in the gut and led to the generally accepted hypothesis that a deregulated immune response against components of the intestinal microbiota is critically involved in IBD pathophysiology…
CD28-dependent Rac1 activation is the molecular target of azathioprine in primary human CD4+ T lymphocytes
Azathioprine and its metabolite 6-mercaptopurine (6-MP) are immunosuppressive drugs that are used in organ transplantation and autoimmune and chronic inflammatory diseases such as Crohn disease. However, their molecular mechanism of action is unknown. In the present study, we have identified a unique and unexpected role for azathioprine and its metabolites in the control of T cell apoptosis by modulation of Rac1 activation upon CD28 costimulation. We found that azathioprine and its metabolites induced apoptosis of T cells from patients with Crohn disease and control patients. Apoptosis induction required costimulation with CD28 and was mediated by specific block- ade of Rac1 activation thro…
Overexpression of STAT-1 by adenoviral gene transfer does not inhibit hepatitis B virus replication.
Objectives Interferons are known to inhibit the replication of hepatitis B viruses (HBV) in several animal models in vitro and in vivo as well in humans. The STAT-1 protein plays a central role in the biological activity of both type I and type II interferons. The lack of functional STAT-1 renders cells and organisms susceptible to bacterial and viral infectious agents. We analysed whether the overexpression of STAT-1 protein enhances the biological interferon response and whether it elicits antiviral acitivity against HBV in vitro. Methods To achieve an efficient STAT-1 overexpression in primary liver cells and hepatoma cells, we generated a recombinant, replication-deficient adenovirus ex…
European small portable rainfall simulators: A comparison of rainfall characteristics
28 páginas, 6 figuras, 2 tablas.- The definitive version is available on: http://www.sciencedirect.com/science/article/pii/S0341816213001252
Efficient gene delivery to the inflamed colon by local administration of recombinant adenoviruses with normal or modified fibre structure
BACKGROUND/AIMSReplication 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.METHODSAn E1/E3 deleted recombinant adenovirus (denoted AdCMVβGal) and an adenovirus with modified fibre structure (denoted AdZ.F(pk7)) both express…
A key pathogenic role for the STAT1/T-bet signaling pathway in T-cell-mediated liver inflammation.
TH1 cytokines have been suggested to contribute to the pathogenesis of T-cell-mediated liver injury and inflammation. However, the molecular signaling pathways involved in such injury are still poorly understood. In the present study, we investigated the role of the STAT1/T-bet signaling pathway in a murine model of T-cell-mediated liver inflammation induced by the application of concanavalin A (Con A) using newly created STAT1 transgenic mice as well as STAT1- and T-bet-deficient mice. Liver injury induced by Con A was associated with an increase of both pSTAT1 and T-bet levels in the liver. Furthermore, functional studies suggested a pathogenic role for STAT1 in Con A-induced liver injury…
A variant of Smurf2 protects mice against colitis-associated colon cancer by inducing transforming growth factor β signaling.
Background & Aims Transforming growth factor (TGF)-β signaling, which is down-regulated by the E3 ubiquitin ligase Smad ubiquitin regulating factor 2 (Smurf2), promotes development of cancer. We identified a splice variant of Smurf2 (ΔE2Smurf2) and investigated its role in colon carcinogenesis in mice. Methods Colitis-associated colon cancer was induced in mice by administration of azoxymethane, followed by 3 cycles of oral administration of dextran sodium sulfate. Messenger RNA levels of Smurf2 in colon tumors and control tissue were measured by quantitative polymerase chain reaction; lymphocyte and cytokine levels were measured in tumor and tissue samples. Results Tumor-infiltrating CD4 +…
Gene transfer approaches for the treatment of inflammatory bowel disease.
The pathogenesis of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease, involves a complex interplay between certain genetic, environmental and immunological factors. Considerable research progress in the last decade defined key inflammatory pathways in the inflamed gut and identified new potential therapeutic targets. Since the current medical treatment with corticosteroids and anti-inflammatory drugs is often associated with undesired side effects and cannot completely cure IBD, these current advances in our understanding of intestinal pathology may now allow the development of new biologic treatment strategies including gene therapy. In this review,…
Activation of Intestinal Epithelial Stat3 Orchestrates Tissue Defense during Gastrointestinal Infection
Gastrointestinal infections with EHEC and EPEC are responsible for outbreaks of diarrheal diseases and represent a global health problem. Innate first-line-defense mechanisms such as production of mucus and antimicrobial peptides by intestinal epithelial cells are of utmost importance for host control of gastrointestinal infections. For the first time, we directly demonstrate a critical role for Stat3 activation in intestinal epithelial cells upon infection of mice with Citrobacter rodentium - a murine pathogen that mimics human infections with attaching and effacing Escherichia coli. C. rodentium induced transcription of IL-6 and IL-22 in gut samples of mice and was associated with activat…
Chemically induced mouse models of intestinal inflammation
Animal models of intestinal inflammation are indispensable for our understanding of the pathogenesis of Crohn disease and ulcerative colitis, the two major forms of inflammatory bowel disease in humans. Here, we provide protocols for establishing murine 2,4,6-trinitro benzene sulfonic acid (TNBS)-, oxazolone- and both acute and chronic dextran sodium sulfate (DSS) colitis, the most widely used chemically induced models of intestinal inflammation. In the former two models, colitis is induced by intrarectal administration of the covalently reactive reagents TNBS/oxazolone, which are believed to induce a T-cell-mediated response against hapten-modified autologous proteins/luminal antigens. In …