Biomedical subjects

Markus F Neurath

Publications and source records attributed to Markus F Neurath.

At least 37 records · Page 2Linked to original sources

PubMed2005

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, dermal lesions of EBI3(-/-) mice contained greater parasite numbers, reaching a peak load that was 2-log higher than in C57BL/6 mice. However, lesions in EBI3(-/-) and wild-type mice resolved after 12 weeks. At early time points, the antigen-specific cytokine response in EBI3(-/-) lymph nodes showed increased levels of IL-4, IL-10 and IL-13 and decreased IFN-gamma production. IL-27 production was restricted to the DC population, since the majority of EBI3 expression in lymph nodes of infected mice was found in CD11c(+) cells. In conclusion, our data show that DC-derived IL-27 is critical for the timely initiation of efficient anti-parasite Th1 immunity early in infections.

Animals↗

PubMed2005

A fluorescence confocal endomicroscope for in vivo microscopy of the upper- and the lower-GI tract.

BACKGROUND: This report describes the development and the clinical evaluation of a novel confocal endomicroscope for obtaining fluorescence images of cellular morphology of the mucosae of the upper- and the lower-GI tract in vivo. The work assessed the feasibility of performing in vivo microscopy at endoscopic examination and evaluated fluorescence imaging protocols. METHODS: Images were collected in real time by using two prototype endoscope configurations, featuring slightly different miniaturized fiber-optic confocal microscopes, fitted integrally into the tips of conventional endoscopes. Confocal scanning was performed at 488 nm illumination for excitation of exogenously applied fluorophores (topical acriflavine and intravenous fluorescein). The images were compared with conventional histology of biopsy specimens and the findings of white-light endoscopy. RESULTS: Confocal endomicroscopy enabled imaging of cellular and subcellular structures (i.e., nuclei) of the GI tract. The crypts of the colonic mucosa, the villi of the terminal ileum and duodenum, the gastric pits of the stomach, and the squamous epithelium of the distal esophagus could be clearly visualized. Acriflavine strongly contrasted the cell nuclei of the surface epithelium, including the absorptive epithelial cells and the mucous secreting goblet cells. Fluorescein stained the extracellular matrix of the surface epithelium and also the subepithelial layers of the lamina propria. Images at increasing depth beneath the epithelium showed the mucosal capillary network. The findings correlated with the histology of biopsy specimens. CONCLUSIONS: The development of a fluorescence confocal endomicroscope makes it practical to examine the upper- and the lower-GI mucosa in cellular detail during otherwise routine endoscopic examination. The results represent a major technical advance in the development of this new optical imaging modality for the in vivo examination of GI tissue.

Acriflavine↗

PubMed2005

Confocal laser endomicroscopy.

A miniaturized confocal microscope was developed that could be integrated in the distal tip of a conventional colonoscope. With this technique, denoted confocal endomicroscopy, subsurface analysis of the gut mucosa and in-vivo histology during ongoing endoscopy are possible in full resolution by point scanning laser analysis. The diagnostic spectrum of confocal endomicroscopy is expanding from screening and surveillance for colorectal cancer to Barrett's esophagus, Helicobacter pylori-associated gastritis, and gastric cancer. The new detailed images seen with confocal laser endomicroscopy allow a unique look on cellular structures at and below the surface of the gut. This review describes the optical and diagnostic possibilities of confocal laser endomicroscopy.

Acriflavine↗

PubMed2005

Endoscopic confocal imaging.

In vivo fluorescence endomicroscopy is a newly developed diagnostic tool enabling virtual in vivo histology of the mucosal layer during ongoing endoscopy. This review summarizes currently available data about the technique and clinical use of confocal endomicroscopy. Indications discussed include colorectal cancer evaluation, ulcerative colitis and surveillance, Barrett's esophagus, and detection of Helicobacter pylori infection in vivo.

Diagnosis, Differential↗

PubMed2005

6-thioguanosine diphosphate and triphosphate levels in red blood cells and response to azathioprine therapy in Crohn's disease.

BACKGROUND & AIMS: Azathioprine is the gold standard for immunosuppressive therapy in Crohn's disease (CD) and its molecular mechanism of action is caused by the metabolite 6-thioguanosine triphosphate (TGTP). In this study we assessed the impact of TGTP levels for monitoring of azathioprine therapy. METHODS: A novel, highly sensitive assay was established to measure levels of TGTP and its precursors 6-thioguanosine monophosphates and 6-thioguanosine diphosphates (TGDP) in red blood cells from 50 CD patients. The results were correlated with clinical outcome. RESULTS: TGTP levels could be quantified in 47 patients and a subgroup of these patients showed significantly high levels of TGDP. 6-thioguanine nucleotide (6-TGN) levels showed a significant correlation with TGDP plus TGTP concentrations, suggesting that active TGTP and its inactive precursor TGDP are the main metabolites within 6-TGN. Patients with 6-TGN levels higher than 100 pmol/8x10(8) red blood cells showed better response rates, on average, than patients with lower 6-TGN levels. The subgroup of patients with higher 6-TGN and increased TGDP levels showed a worse outcome with lower response rates, more flares, and higher infliximab demand than patients with high 6-TGN, low TGDP, and predominantly detectable TGTP levels. CONCLUSIONS: This study shows that quantification of TGTP levels can be used to monitor azathioprine therapy in inflammatory bowel disease patients. Furthermore, the data suggest that TGDP levels of more than 15% of total 6-TGN levels may be a useful surrogate parameter to predict poor response in a subgroup of azathioprine-treated patients.

Adult↗

PubMed2005

Diagnosing Helicobacter pylori in vivo by confocal laser endoscopy.

BACKGROUND & AIMS: Confocal laser endomicroscopy enables subsurface microscopic imaging of living tissue during ongoing endoscopy. This case report describes the in vivo detection of Helicobacter pylori by endomicroscopy. METHODS: Endomicroscopy (Pentax, Tokyo, EC-3870CIFK) was performed by using two different contrast stains: Topical Acriflavine in addition to intravenously applied fluorescein netted the surface and allowed identification of focal accumulation of Helicobacter pylori at the surface and in deeper layer of the gastric epithelium. Biopsies were performed at the antrum and corpus for urease testing and histology. In addition, biopsies were cultured for Helicobacter pylori. Cultured bacteria were re-assessed ex vivo using confocal microscopy with and without acriflavine staining. RESULTS: Helicobacter pylori infection could be detected in a 70-year-old male by endomicroscopy. Accumulated, as well as single bacteria, could be observed and the distinct shape and flagella of Helicobacter pylori could be identified. Helicobacter pylori infection was proved by histology. Furthermore, ex vivo examination of cultures proved the presence of Helicobacter pylori and the active uptake of acriflavine into the bacteria. CONCLUSIONS: Endomicroscopy is a new diagnostic approach, which enables the immediate diagnosis of Helicobacter pylori in vivo during standard video endoscopy.

Acriflavine↗

PubMed2005

Chromo- and magnifying endoscopy for colorectal lesions.

It is essential to identify patients with premalignant or early malignant changes during colonoscopy. Thus, curative resection can be offered. At present, endoscopy can be performed with new powerful high-resolution or magnifying endoscopes. Comparably to the rapid development in chip technology, the optic features of the newly designed endoscopes offer resolutions which allow new mucosal surface details to be seen. In conjunction with chromoendoscopy, the newly discovered tool video endoscopy is much easier and more impressive than with conventional fibre optics. This review summarizes the value of magnifying endoscopy in the lower gastrointestinal tract and focuses on colorectal lesions.

Adenoma↗

PubMed2005

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 is essential to induce interferon-gamma-producing TH1 cells, whereas IL-23 mediates effector functions. The latest cytokine added to this cytokine family is IL-27. IL-27 has the unique feature to act on naive T cells, rendering them susceptible to IL-12 signaling. Thus, IL-27 may be essential for the early events of a cell-mediated immune response. This review focuses on these novel cytokines and their role in cell-mediated immune responses and discusses differences and common features within the family of IL-12-related cytokines.

Animals↗

PubMed2005

Activation pattern of signal transducers and activators of transcription (STAT) factors in inflammatory bowel diseases.

OBJECTIVES: Cytokine signaling pathways involving transcription factors of the signal transducers and activators of transcription (STAT) family play a key role in the pathogenesis of inflammatory bowel diseases (IBD). STAT proteins are latent cytoplasmic transcription factors that induce transcription upon phosphorylation, dimerization, and nuclear translocation. However, their activation pattern in IBD is poorly understood. The aim of our study was to characterize STAT-expression in IBD. METHODS: Mononuclear cells were isolated from 36 colonic specimens of Crohn's disease, ulcerative colitis, or from control patients. Cells were stimulated overnight with antibodies against human CD2 and CD28 and mononuclear cells were analyzed by flow cytometry. Alternatively, CD4(+) T cells were immunomagnetically separated and then assessed by flow cytometry. Intracellular stainings of the following transcription factors were performed: STAT-1, STAT-2, STAT-3, STAT-4, and STAT-6. In addition, immunofluorescence staining on cryosections for phosphorylated STAT-1 and STAT-3 was performed. RESULTS: Average expression of the IFN-gamma inducible transcription factor STAT-1 was increased in Crohn's disease as compared to patients with ulcerative colitis and control patients. However, levels of phospho-STAT-1 were surprisingly not markedly upregulated in IBD as compared to controls. In contrast, STAT-3 and phospho-STAT-3 levels were significantly increased in IBD patients as compared to controls (p < 0.01). No differences could be detected in STAT-6 levels. Finally, average expression of STAT-2, which is involved in type I interferon signalling, was downregulated in IBD as compared to control patients. CONCLUSIONS: The analysis of STAT activation patterns could serve as a helpful tool to characterize intestinal inflammation. Furthermore, the IL-6/STAT-3 rather than the IFN-gamma/STAT-1 signaling pathway emerges as a key target for the development of future therapeutic concepts in IBD.

CD4-Positive T-Lymphocytes↗

PubMed2005

The IL-6R alpha chain controls lung CD4+CD25+ Treg development and function during allergic airway inflammation in vivo.

The cytokine IL-6 acts via a specific receptor complex that consists of the membrane-bound IL-6 receptor (mIL-6R) or the soluble IL-6 receptor (sIL-6R) and glycoprotein 130 (gp130). In this study, we investigated the role of IL-6R components in asthma. We observed increased levels of sIL-6R in the airways of patients with allergic asthma as compared to those in controls. In addition, local blockade of the sIL-6R in a murine model of late-phase asthma after OVA sensitization by gp130-fraction constant led to suppression of Th2 cells in the lung. By contrast, blockade of mIL-6R induced local expansion of Foxp3-positive CD4+CD25+ Tregs with increased immunosuppressive capacities. CD4+CD25+ but not CD4+CD25- lung T cells selectively expressed the IL-6R alpha chain and showed IL-6-dependent STAT-3 phosphorylation. Finally, in an in vivo transfer model of asthma in immunodeficient Rag1 mice, CD4+CD25+ T cells isolated from anti-IL-6R antibody-treated mice exhibited marked immunosuppressive and antiinflammatory functions. IL-6 signaling therefore controls the balance between effector cells and Tregs in the lung by means of different receptor components. Furthermore, inhibition of IL-6 signaling emerges as a novel molecular approach for the treatment of allergic asthma.

Adult↗

PubMed2005

Illuminating the role of type I IFNs in colitis.

Recently, type I interferons IFN-alpha and IFN-beta (IFN-alpha/beta) have been evaluated in pilot clinical trials for the treatment of active ulcerative colitis. However, the underlying mechanisms that may contribute to a potential therapeutic effect are incompletely understood. A new study in this issue demonstrates a protective role for IFN-alpha/beta, induced by activation of a Toll-like receptor 9-dependent pathway, in a rodent model of experimental colitis.

Animals↗

PubMed2005

Involvement of IL-6 in the pathogenesis of inflammatory bowel disease and colon cancer.

Inflammatory bowel disease (IBD), which consists of Crohn's disease and ulcerative colitis, is defined as a chronic inflammation of the gastrointestinal tract. The etiopathogenetic mechanisms underlying the development of IBD are still not completely understood, and the therapeutic strategies used thus far have been limited to mostly evidence-based principles. There is growing evidence that the pro-inflammatory cytokine interleukin (IL)-6 plays a crucial part in the uncontrolled intestinal inflammatory process, which is a main characteristic of IBD. There is elevated production of IL-6 and its soluble receptor (sIL-6R) by intestinal macrophages and CD4+T-cells. The increased formation of IL-6-sIL-6R complexes that interact with gp130 on the membrane of CD4+T-cells (trans-signaling) lead to an increased expression and nuclear translocation of STAT3, which causes the induction of anti-apoptotic genes, such as Bcl-xl. This leads to an augmented resistance of lamina propria T-cells to apoptosis. The ensuing T-cell expansion contributes to the perpetuation of chronic intestinal inflammation. This understanding concerning the predominant pathogenic role of an IL-6-dependent inflammatory cascade may lead to the development of new therapeutic strategies in the treatment of this disease. Recent studies have also suggested a potential role of IL-6-sIL-6R in the pathogenesis of colon cancer and, therefore, imply a possible novel therapeutic strategy targeting the sIL-6R and ensuing IL-6 trans-signaling.

Animals↗

PubMed2005

Angiogenesis, immune system and growth factors: new targets in colorectal cancer therapy.

Colorectal 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.

Angiogenesis Inhibitors↗

PubMed2005

Mucosal immunoregulation: transcription factors as possible therapeutic targets.

Much progress has been recently made with regard to our understanding of the mucosal immune system in health and disease. In particular, it has been shown that uncontrolled mucosal immune responses driven by lymphocytes or non-lymphoid cells may lead to immunological diseases such as allergy, hypersensitivity and inflammation. Thus, a more detailed understanding of mucosal immune regulation and decision making at mucosal surfaces is essential for a better understanding of mucosal immune responses in health and disease. Antigen presenting cells and T lymphocytes play a key role in controlling mucosal immune responses. To deal with this key task, T helper cells differentiate into functionally distinct subsets: TH1 (CD4+ T Helper cells), TH2, TH3, Tr1, and CD4+CD25+ T (Treg) cells. This review summarizes the role of antigen presenting cells, eosinophils, mast cells and T-cell subsets in the pathogenesis of allergic inflammation and intestinal inflammation. Furthermore, we discuss novel immunological treatment modalities for allergic inflammation (e.g. allergic asthma) and chronic intestinal inflammation (e.g. inflammatory bowel diseases (IBD)) such as the control of the expression of transcription factors to redirect pathological immune responses.

Animals↗

PubMed2004

Cutting edge: TGF-beta signaling is required for the in vivo expansion and immunosuppressive capacity of regulatory CD4+CD25+ T cells.

Data regarding the role of TGF-beta for the in vivo function of regulatory CD4(+)CD25(+) T cells (Treg) are controversial. A transgenic mouse model with impaired TGF-beta signaling specifically in T cells was used to assess the role of endogenous TGF-beta for the in vivo function of CD4(+)CD25(+) Treg in a murine model of colitis induced by dextran sulfate. Transfer of wild-type, but not transgenic CD4(+)CD25(+) Treg was found to suppress colitis in wild-type mice. In addition, by transferring CFSE-labeled CD4(+)CD25(+) Treg we could demonstrate that endogenous TGF-beta promotes the expansion of CD4(+)CD25(+) Treg in vivo. Transgenic mice themselves developed reduced numbers of peripheral CD4(+)CD25(+) Treg and were more susceptible to the induction of colitis, which could be prevented by the transfer of wild-type Treg. These data indicate that TGF-beta signaling in CD4(+)CD25(+) Treg is required for their in vivo expansion and suppressive capacity.

Adoptive Transfer↗

PubMed2004

Anti-interleukin-12 antibody for active Crohn's disease.

BACKGROUND: Crohn's disease is associated with excess cytokine activity mediated by type 1 helper T (Th1) cells. Interleukin-12 is a key cytokine that initiates Th1-mediated inflammatory responses. METHODS: This double-blind trial evaluated the safety and efficacy of a human monoclonal antibody against interleukin-12 (anti-interleukin-12) in 79 patients with active Crohn's disease. Patients were randomly assigned to receive seven weekly subcutaneous injections of 1 mg or 3 mg of anti-interleukin-12 per kilogram of body weight or placebo, with either a four-week interval between the first and second injection (Cohort 1) or no interruption between the two injections (Cohort 2). Safety was the primary end point, and the rates of clinical response (defined by a reduction in the score for the Crohn's Disease Activity Index [CDAI] of at least 100 points) and remission (defined by a CDAI score of 150 or less) were secondary end points. RESULTS: Seven weeks of uninterrupted treatment with 3 mg of anti-interleukin-12 per kilogram resulted in higher response rates than did placebo administration (75 percent vs. 25 percent, P=0.03). At 18 weeks of follow-up, the difference in response rates was no longer significant (69 percent vs. 25 percent, P=0.08). Differences in remission rates between the group given 3 mg of anti-interleukin-12 per kilogram and the placebo group in Cohort 2 were not significant at either the end of treatment or the end of follow-up (38 percent and 0 percent, respectively, at both times; P=0.07). There were no significant differences in response rates among the groups in Cohort 1. The rates of adverse events among patients receiving anti-interleukin-12 were similar to those among patients given placebo, except for a higher rate of local reactions at injection sites in the former group. Decreases in the secretion of interleukin-12, interferon-gamma, and tumor necrosis factor alpha by mononuclear cells of the colonic lamina propria accompanied clinical improvement in patients receiving anti-interleukin-12. CONCLUSIONS: Treatment with a monoclonal antibody against interleukin-12 may induce clinical responses and remissions in patients with active Crohn's disease. This treatment is associated with decreases in Th1-mediated inflammatory cytokines at the site of disease.

Adult↗

PubMed2004

Anti-TNF strategies in stenosing and fistulizing Crohn's disease.

BACKGROUND: Stenoses and fistulas are frequent complications in patients with Crohn's disease (CD). They represent a major diagnostic and therapeutic challenge and surgical intervention is often required. The availability of novel, anti-TNF strategies for therapy has raised the question as to what extent these new treatment options have impact on the clinical decision-making process regarding the necessity for surgery. DISCUSSION: A short overview of the current pathophysiological understanding of CD, focusing on the immunology of the intestinal mucosa, is given. Then the problems of proper clinical management of stenoses and fistulas are addressed. With regard to symptomatic stenoses, attention will be given to novel diagnostic tools for the distinction between inflammatory and fibrotic stenoses, and our clinical experience with the treatment of symptomatic inflammatory stenoses with infliximab will be discussed. With regard to fistulizing CD, the data that are currently available for medical therapy are summarized with special reference to the studies on the efficacy of anti-TNF treatment. CONCLUSION: With regard to moderately and severe inflammatory stenoses, medical treatment with infliximab may be an option after careful assessment of the inflammatory nature of the stenosis and exclusion of a septic focus. With regard to fistulas, anti-TNF treatment is a valuable option that is likely to improve the clinical outcome. Based on the available data, however, anti-TNF treatment cannot yet replace surgical intervention when necessary. Prospective trials of medical therapy and a combination of medical and surgical therapy for complex fistulas and internal fistulas are needed to define the potential and the limitations of these novel therapeutic approaches.

Antibodies, Monoclonal↗

PubMed2004

A critical regulatory role of leucin zipper transcription factor c-Maf in Th1-mediated experimental colitis.

In this study, we investigated the role of c-Maf, a transcription factor known to induce IL-4 production, in inflammatory bowel diseases and experimental colitis. Although Crohn's disease (CD) is associated with low IL-4 production by T-bet-expressing Th1 cells in the lamina propria, surprisingly a higher expression of c-Maf in these cells was found as compared with control patients. The relevance of this finding was further evaluated in an animal model of CD induced by adoptive transfer of CD4(+)CD62L(+) T cells in RAG-deficient mice. In this Th1-mediated model, an increase of c-Maf-expressing T lymphocytes in the lamina propria over time was observed. Interestingly, adoptive transfer of c-Maf transgenic CD4(+)CD62L(+) T cells in RAG-1-deficient mice resulted in an IL-4-dependent inability to induce colitis and suppressed colitis activity induced by wild-type CD4(+)CD62L(+) T cells. In contrast, transfer of CD4(+)CD62L(-) T cells from c-Maf transgenic, but not wild-type mice induced colitis and augmented colitis induced by CD4(+)CD62L(+) T cells from wild-type mice in an IL-4-independent pathway, as determined by macroscopic, histologic, and endoscopic criteria. This was associated with an accumulation of CD4(+) T-bet(+) CD25(+) effector Th1 cells in the lamina propria of colitic mice. Our results reveal a novel regulatory role of c-Maf in colitis. Although overexpression of c-Maf in naive T cells prevents Th1-mediated colitis, overexpression of c-Maf in memory T-bet(+) Th1 cells regulates CD25 expression and augments such colitis. Targeting of c-Maf in memory T cells in CD appears to be an attractive target for therapeutic interventions.

Animals↗