1,721,049 research outputs found
TGF-beta as a T cell regulator in colitis and colon cancer
No full textTGF-β is a pleiotropic cytokine with powerful immunosuppressive functions. Mice deficient for TGF-β1 show a dramatic phenotype with severe multiorgan inflammation and die shortly after birth. Recent investigations have highlighted the role of TGF-β in suppression of T cell mediated autoimmune inflammation and anti-tumor immunity. In addition to its direct anti-inflammatory effects on T cells, TGF-β has been implicated as central regulator of regulatory T cells. TGF-β not only mediates the suppression of effector T cells by Tregs, recent evidence also reveals a role for TGF-β along with TCR stimulation in the peripheral induction of regulatory T cells from naïve CD4+CD25- cells
High resolution colonoscopy in live mice
No full textEndoscopy in humans is a powerful method for physicians to examine the gut for inflammatory or neoplastic changes. In medical and immunological research, animal models of intestinal diseases are established key tools to investigate the mucosal immune system, colitis and cancer development in the gut. Moreover, such models represent valid systems for testing of novel drugs. In the past, mice had to be killed in order to analyze colitis activity and tumor development. The following protocol describes a method to perform high resolution endoscopic monitoring of live mice. Mice developing colitis or colonic tumors are anesthetized and examined with a miniendoscope. The endoscope is introduced via the anus and the colon is carefully insufflated with an air pump. Endoscopic pictures obtained are of high quality and allow the monitoring and grading of tumors and inflammation. In addition, colonic biopsies can be taken. This protocol can be completed within 1 h
Angiogenesis, immune system and growth factors: new targets in colorectal cancer therapy
No full textColorectal cancer is the second most common malignant human neoplasia. Over recent years, many efforts have been performed in order to develop and improve therapeutic protocols, and many advances have been accomplished in both the field of adjuvant and palliative therapy. Most of the chemotherapic agents currently used in the clinical setting are the products of decades of research aimed at inhibiting the uncontrolled growth of dysplastic cells. However, new frontiers in this field have recently been opened, with the identification of key molecules involved in physiologic mechanisms that are of fundamental importance for cancer development and progression. Tumor-induced angiogenesis, the cancer-immune system crosstalk and the effect of growth factors on dysplastic cells represent new fields of investigation for anticancer therapy
In vitro generation of CD4+ CD25+ regulatory cells from murine naive T cells
Full text linkCD4+CD25+ regulatory T cells (Tregs) are crucial for the maintenance of immunological tolerance. Recent data indicate that Tregs not only develop in the thymus during ontogeny but can also differentiate from naive T cells in the periphery. The following protocoldescribes a method by which Tregs are generated in vitro by stimulation of naive T cells in the presence of transforming growth factorP (Ti-Tregs). In v/tro-induced regulatory T cells express markers of conventional Treg such as CD25 and the genetic programcommitting transcription factor FoxP3. Functionally the in v/tro-generated Ti-Tregs suppress T-cell activation and proliferation whilein vivo these cells have been proven to control inflammation in different animal models, suggesting a potential use of these cells forimmunotherapy. The protocol can be completed within 5 days
Drug insight: novel small molecules and drugs for immunosuppression
No full textGastrointestinal diseases can result from the inadequate or excessive response of the immune system to self or innocuous antigens. Moreover, the physiologic activation of the immune system against non-self antigens is a major clinical problem in liver organ transplantation. At present, many drugs are available that suppress the activation of the immune system, although most of the currently used immunosuppressive drugs lack specificity in terms of their molecular targets and, therefore, have the potential to generate numerous side effects. The advances that have been made in understanding the molecular events that underlie the activation of the immune system have led to the development of a new generation of 'small molecules' that are endowed with immunosuppressive properties and can serve as immunomodulatory agents. Among these new small molecules, inhibitors of Janus kinase 3, p21-Rac1 and p38 mitogen-activated protein kinase represent the most innovative approach to immunosuppression, and could be a promising alternative to current immunosuppressive therapies. Here, we report on the progress that has been made in the development of small molecules in the field of gastroenterology
Transforming growth factor beta induced FoxP3+ regulatory T cells suppress Th1 mediated experimental colitis
No full textBackground and aims: The imbalance between effector and regulatory T cells plays a central role in the pathogenesis of inflammatory bowel diseases. In addition to the thymus, CD4+CD25+ regulatory T cells can be induced in the periphery from a population of CD25- T cells by treatment with transforming growth factor β (TGF-β). Here, we analysed the in vivo function of TGF-β induced regulatory T (Ti-Treg) cells in experimental colitis. Methods: Ti-Treg cells were generated in cell culture in the presence or absence of TGF-β and tested for their regulatory potential in experimental colitis using the CD4+CD62L+ T cell transfer model. Results: Ti-Treg cells significantly suppressed Th1 mediated colitis on CD4+CD62L+ T cell transfer in vivo, as shown by high resolution endoscopy, histology, immunohistochemistry, and cytokine analysis. Further analysis of in vivo and in vitro expanded Ti-Treg cells showed that exogenous interleukin 2 (IL-2) was crucial for survival and expansion of these cells. Conclusion: Our data suggest that regulatory Ti-Treg cells expand by TGF-β and exogenous IL-2 derived from effector T cells at the site of inflammation. In addition to Tr1 and thymic CD4+CD25+ T cells, peripheral Ti-Treg cells emerge as a class of regulatory T cells with therapeutic potential in T cell mediated chronic intestinal inflammation
In vivo imaging of colitis and colon cancer development in mice using high resolution chromoendoscopy
No full textBackground: 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 injection needles as well as surface staining with methylene blue in order to visualise the surface of the crypts and the pit pattern architecture. Results: Endoscopic pictures obtained were of high quality and allowed monitoring and grading of disease. Scoring of colitis activity as well as tumour size and growth was possible. In addition, pit pattern analysis using chromoendoscopy permitted discrimination between inflammatory and neoplastic changes. Biopsies yielded enough tissue for molecular and histopathological analyses. Conclusions: In summary, chromoendoscopy in mice allows monitoring of the development of colitis and colon cancer with high resolution. Manipulations such as local injection of reagents or taking biopsies can be performed easily
Cutting edge: TGF-beta induces a regulatory phenotype in CD4+CD25- T cells through Foxp3 induction and down-regulation of Smad7
No full textCD4+ CD25+ regulatory cells are a subpopulation of T lymphocytes of thymic origin. However, recent data suggest an alternative commitment of regulatory T cells in the periphery, although the precise mechanism is unknown. In the present work, we demonstrate that TGF-β is able to induce Foxp3 expression and subsequently a regulatory phenotype in CD4+ CD25- peripheral murine T cells. Similarly, TGF-β induced Foxp3 in human CD4+ CD25- T cells. Moreover, we show that the inhibitory Smad7 protein that is normally induced by TGF-β and limits TGF-β signaling, is strongly down-regulated by Foxp3 at the transcriptional level. Foxp3-mediated down-regulation of Smad7 subsequently rendered CD4+ CD25- T cells highly susceptible to the morphogenic and regulatory effects of TGF-β signaling via Smad3/4. In summary, we demonstrate that TGF-β induces a regulatory phenotype in CD4+ CD25- T cells through the induction of Foxp3 and a positive autoregulatory loop of TGF-β signaling due to the absence of Smad7
IL-6 signaling promotes tumor growth in colorectal cancer
No full textRecent investigations support an important role for TGF-β in the development of colorectal cancer. However, the molecular consequences of TGF-β signaling in the colon remains incompletely understood. In a recent study in Immunity, we analyzed the role of TGF-β in a murine model of colon cancer. Using transgenic mice overexpressing TGF-β or a dominant negative TGF-β receptor II under control of the CD2 minigene, we show that TGF-β 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-β 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-β-dependent IL-6 trans-signaling prevented tumor progression in vivo. Similar to these observations in mice, here we show that human colon cancer tissue expressed only low amounts of membrane bound IL-6R. In contrast, expression and activity of the matrix metalloproteinase TACE were increased. In summary, our data provide novel insights into the role of TGF-β signaling in colorectal cancer and suggest novel therapeutic approaches for colorectal cancer based on an inhibition of TGF-β-dependent IL-6 trans-signaling
EBV-induced gene 3 transcription is induced by TLR signaling in primary dendritic cells via NF-kappa B activation
No full textThe 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 footpriniing 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 were sufficient to transactivate the EBI3 promoter in EBD-deficient 293 cells. Finally, induced EBI3 gene expression in DCs was reduced or abrogated in TLR-2/TLR4, TLR9, and MyD88 knockout mice, whereas both basal and inducible EBI3 mRNA levels in DCs were strongly suppressed in NF-κB p50-deficient mice. In summary, these data suggest that EBI3 expression in DCs is transcriptionally regulated by TLR signaling via MyD88 and NF-κB. Thus, EBI3 gene transcription in DCs is induced rapidly by TLR signaling during innate immune responses preceding cytokine driven Th cell development
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