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Desch A.,University of Heidelberg | Strozyk E.A.,Institute of Molecular Immunology | Bauer A.T.,University of Heidelberg | Huck V.,University of Heidelberg | And 3 more authors.
American Journal of Pathology | Year: 2012

Tumor cell extravasation is a critical step in the metastatic cascade and requires interaction between the tumor cell and the endothelium. Although cancer progression depends on a complex network of mechanisms, including inflammation and coagulation, the involvement of tumor-induced endothelium activation and the subsequent release of procoagulatory factors in this process are not well understood. Using tissue sections from patients with malignant melanoma, immunofluorescence studies for the presence of von Willebrand factor (VWF) clearly demonstrated endothelium activation and the formation of ultra-large VWF fibers in these patients. In vitro analyses revealed that supernatants from highly invasive melanoma cells induced an acute endothelium activation measured by VWF, P-selectin, and angiopoietin-2 release. Proteome profiling identified vascular endothelial growth factor A (VEGF-A) as the main mediator of endothelium activation. Inhibition and knock-down of VEGF-A in melanoma cells led to a rigorous decrease in VWF exocytosis. Selective small-interfering RNA to matrix metalloproteinase-2 (MMP-2) inhibited endothelium activation, and this effect correlated with reduced VEGF-A content in the supernatants of melanoma cells. Further experiments showed that active MMP-2 regulates VEGF-A in melanoma cells on a transcriptional level via an integrin αvβ5/ phosphoinositide-3-kinase-dependent pathway. In conclusion, these results indicate an important role of VEGF-A in acute endothelium activation and provide clear evidence that MMP-2 plays a pivotal role in the autocrine regulation of VEGF-A expression in melanoma cells. © 2012 American Society for Investigative Pathology. Source


Karalar L.,University of Regensburg | Lindner J.,University of Regensburg | Lindner J.,Institute of Molecular Immunology | Schimanski S.,University of Regensburg | And 3 more authors.
Clinical Microbiology and Infection | Year: 2010

Human bocavirus (HBoV) was recently described as a new member of the Parvoviridae. In order to investigate the suggested association of HBoV with respiratory and gastric disease in infants and young children, sera of 357 paediatric patients hospitalized with infectious and non-infectious diseases were retrospectively analyzed for the presence of HBoV DNA and virus-specific antibodies using quantitative PCR and ELISA, respectively. HBoV seroprevalence was determined to range from 25% in infants younger than 1 year of age to 93% in children aged more than 3 years. Viral loads between 1 × 10 2 and 1.2 × 10 6 geq/mL were observed in 6.7% (20/297) of sera obtained preferentially from young children suffering from infectious diseases. HBoV genomes were furthermore detected in 5% (3/60) of sera collected from individuals with non-infectious illnesses. HBoV DNA was present most frequently in patients with respiratory disease (9.6%). Whereas only 5.2% of patients with upper respiratory tract disease were viraemic, HBoV DNA was found in 14.6% and 10.0% of patients with lower respiratory tract illness and pneumonia, respectively. Acute HBoV infections were also observed in 7.5% of patients with gastroenteritis and in one child with inflammatory bowel disease. None of 77 patients hospitalized for various other infectious diseases (e.g. rash, urinary tract infection, meningitis) displayed viraemia. In 60.9% and 47.8% of DNA-positive children, HBoV-specific IgM and IgG was observed, respectively. The present prospective study provides comprehensive data on the clinical association of acute HBoV infection with respiratory illness and on the seroprevalence of virus-specific antibodies in children. © 2009 The Authors. Journal Compilation. Source


Knolle P.A.,Institute of Molecular Immunology | Thimme R.,University Hospital Freiburg
Gastroenterology | Year: 2014

The liver has unique immune regulatory functions that promote the induction of tolerance rather than responses to antigens encountered locally. These functions are mediated by local expression of coinhibitory receptors and immunosuppressive mediators that help prevent overwhelming tissue damage. Over the years, we have gained more insight into the local regulatory cues that determine the functional complexity of immune responses regulated locally in the liver. Both the unique hepatic microenvironment and the particular liver sinusoidal cell populations, in addition to hepatocytes, actively modulate immune responses locally in the liver and thereby determine the outcome of hepatic immune responses. This is of high biological and clinical relevance in hepatitis B virus and hepatitis C virus infections, which can cause acute and persistent infections associated with chronic inflammation in humans that eventually progress to cirrhosis and hepatocellular carcinoma. Here, we review current knowledge about the balance between immunity and tolerance in the liver and how this may affect our understanding of the determinants of hepatitis B virus and hepatitis C virus clearance, persistence, and virus-induced liver disease. Source


Oak P.S.,Ludwig Maximilians University of Munich | Kopp F.,Ludwig Maximilians University of Munich | Thakur C.,Max Planck Institute of Biochemistry | Ellwart J.W.,Institute of Molecular Immunology | And 5 more authors.
International Journal of Cancer | Year: 2012

A major obstacle in the successful treatment of cancer is the occurrence of chemoresistance. Cancer cells surviving chemotherapy and giving rise to a recurrence of the tumor are termed cancer stem cells and can be identified by elevated levels of certain stem cell markers. Eradication of this cell population is a priority objective in cancer therapy. Here, we report elevated levels of stem cell markers in MCF-7 mammospheres. Likewise, an upregulation of HER2 and its differential expression within individual cells of mammospheres was observed. Sorting for HER2high and HER2low cells revealed an upregulation of stem cell markers NANOG, OCT4 and SOX2 in the HER2 low cell fraction. Accordingly, HER2low cells also showed reduced proliferation, ductal-like outgrowths and an increased number of colonies in matrigel. Xenografts from subcutaneously injected HER2low sorted cells exihibited earlier onset but slower growth of tumors and an increase in stem cell markers compared to tumors developed from the HER2 high fraction. Treatment of mammospheres with salinomycin reduced the expression of SOX2 indicating a selective targeting of cancer stem cells. Trastuzumab however, did not reduce the expression of SOX2 in mammospheres. Furthermore, a combinatorial treatment of mammospheres with trastuzumab and salinomycin was superior to single treatment with each drug. Thus, targeting HER2 expressing tumors with anti-HER2 therapies will not necessarily eliminate cancer stem cells and may lead to a more aggressive cancer cell phenotype. Our study demonstrates efficient killing of both HER2 positive cells and cancer stem cells, hence opening a possibility for a new combinatorial treatment strategy. Copyright © 2012 UICC. Source


Tschoep-Lechner K.,Ludwig Maximilians University of Munich | Tschoep-Lechner K.,Institute of Molecular Immunology | Drexler I.,TU Munich | Hammer D.,Institute of Molecular Immunology | And 7 more authors.
International Journal of Hyperthermia | Year: 2012

Purpose: Adding hyperthermia to chemotherapy improved the clinical outcome of patients with high risk soft tissue sarcoma. Further improvement might be possible if combined with vaccination strategies. As no sarcoma-associated antigens are known, the ectopic expression of a surrogate marker for which immune monitoring tools are available, is envisaged. We tested surrogate marker transfer into sarcoma cells in vitro using modified vaccinia virus Ankara (MVA), which has well established clinical safety. We examined its robustness against standard sarcoma treatment modalities, such as ifosfamide and hyperthermia. Materials and methods: We transduced sarcoma cell lines and primary tumour cells from sarcoma patients with MVA encoding the human tyrosinase gene (MVA-hTyr). Kinetics of tyrosinase expression and the potency to activate tyrosinase-specific cytotoxic T cells were assessed. In addition cells were exposed to chemotherapy and heat, imitating the clinical setting. Results: Tyrosinase was ectopically expressed in sarcoma cells. Infected cells presented tyrosinase epitopes for T cell recognition even if exposed to ifosfamide/heat. Conclusions: As sarcoma patients receive surgery up front or after neoadjuvant systemic chemotherapy/hyperthermia, tumour material is generally available. Our data document that primary sarcoma cells can be infected with MVA-hTyr in vitro and antigen presentation is not affected by ifosfamide or heat treatment. Infected cells can serve as a source for vaccine preparation. MVA-hTyr infection of tumour cells lacking defined antigens is a feasible system to introduce a robust surrogate marker to provide an immune monitoring marker for assessing the induction of antigen-specific T cell activation. © 2012 Informa UK Ltd All rights reserved. Source

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