24 results on '"Günther Staffler"'
Search Results
2. Osteopontin is a key player for local adipose tissue macrophage proliferation in obesity
- Author
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Matteo Tardelli, Karina Zeyda, Veronica Moreno-Viedma, Bettina Wanko, Nicole G. Grün, Günther Staffler, Maximilian Zeyda, and Thomas M. Stulnig
- Subjects
Internal medicine ,RC31-1245 - Abstract
Objective: Recent findings point towards an important role of local macrophage proliferation also in obesity-induced adipose tissue inflammation that underlies insulin resistance and type 2 diabetes. Osteopontin (OPN) is an inflammatory cytokine highly upregulated in adipose tissue (AT) of obese and has repeatedly been shown to be functionally involved in adipose-tissue inflammation and metabolic sequelae. In the present work, we aimed at unveiling both the role of OPN in human monocyte and macrophage proliferation as well as the impact of OPN deficiency on local macrophage proliferation in a mouse model for diet-induced obesity. Methods: The impact of recombinant OPN on viability, apoptosis, and proliferation was analyzed in human peripheral blood monocytes and derived macrophages. Wild type (WT) and OPN knockout mice (SPP1KO) were compared with respect to in vivo adipose tissue macrophage and in vitro bone marrow-derived macrophage (BMDM) proliferation. Results: OPN not only enhanced survival and decreased apoptosis of human monocytes but also induced proliferation similar to macrophage colony stimulating factor (M-CSF). Even in fully differentiated monocyte-derived macrophages, OPN induced a proliferative response. Moreover, proliferation of adipose tissue macrophages in obese mice was detectable in WT but virtually absent in SPP1KO. In BMDM, OPN also induced proliferation while OPN as well as M-CSF-induced proliferation was similar in WT and SPP1KO. Conclusions: These data confirm that monocytes and macrophages not only are responsive to OPN and migrate to sites of inflammation but also they survive and proliferate more in the presence of OPN, a mechanism also strongly confirmed in vivo. Therefore, secreted OPN appears to be an essential player in AT inflammation, not only by driving monocyte chemotaxis and macrophage differentiation but also by facilitating local proliferation of macrophages. Keywords: OPN, Obesity, Inflammation, Adipose tissue, Adipose tissue macrophage
- Published
- 2016
- Full Text
- View/download PDF
3. Antibody-mediated targeting of cleavage-specific OPN-T cell interactions.
- Author
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Bettina Wanko, Matteo Tardelli, Alexander Jürets, Angelika Neuhofer, Gerhard Prager, John Morser, Lawrence L Leung, Günther Staffler, Maximilian Zeyda, and Thomas M Stulnig
- Subjects
Medicine ,Science - Abstract
T cells are crucial players in obesity-mediated adipose tissue inflammation. We hypothesized that osteopontin (OPN), an inflammatory protein with enhanced activity when proteolytically cleaved, affects the number of viable T cells in adipose tissue and assessed inhibition of the interaction between T cells and thrombin and matrix metalloproteinases-cleaved OPN using antibodies and postimmune sera. Gene expression of T cell markers in adipose tissue from wild-type (wt) and Spp1-/- (OPN deficient) mice was analyzed after 16 weeks of high fat diet (HFD) or low fat diet (LFD) feeding. CD3, CD8 and OPN gene expression in omental adipose tissue from individuals with obesity was measured. OPN-T cell interactions were assessed with a fluorescence-based adhesion assay and blocked with antibodies targeting OPN. Comparison of T cell gene expression in adipose tissue from wt and Spp1-/- mice showed that OPN affected the number of T cells while in humans, levels of OPN correlated with T cell markers in omental adipose tissue. The interaction between T cells and cleaved OPN was blocked by postimmune sera following OPN peptide vaccinations and with monoclonal antibodies. In conclusion, levels of OPN affected the number of T cells in obesity and antibodies against cleaved OPN antagonize OPN-T cell interactions.
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- 2019
- Full Text
- View/download PDF
4. Inhibition of Cellular Adhesion by Immunological Targeting of Osteopontin Neoepitopes Generated through Matrix Metalloproteinase and Thrombin Cleavage.
- Author
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Alexander Jürets, Marie Le Bras, Günther Staffler, Gesine Stein, Lukas Leitner, Angelika Neuhofer, Matteo Tardelli, Edvin Turkof, Maximilian Zeyda, and Thomas M Stulnig
- Subjects
Medicine ,Science - Abstract
Osteopontin (OPN), a secreted protein involved in inflammatory processes and cancer, induces cell adhesion, migration, and activation of inflammatory pathways in various cell types. Cells bind OPN via integrins at a canonical RGD region in the full length form as well as to a contiguous cryptic site that some have shown is unmasked upon thrombin or matrix metalloproteinase cleavage. Thus, the adhesive capacity of osteopontin is enhanced by proteolytic cleavage that may occur in inflammatory conditions such as obesity, atherosclerosis, rheumatoid arthritis, tumor growth and metastasis. Our aim was to inhibit cellular adhesion to recombinant truncated proteins that correspond to the N-terminal cleavage products of thrombin- or matrix metalloproteinase-cleaved OPN in vitro. We specifically targeted the cryptic integrin binding site with monoclonal antibodies and antisera induced by peptide immunization of mice. HEK 293 cells adhered markedly stronger to truncated OPN proteins than to full length OPN. Without affecting cell binding to the full length form, the raised monoclonal antibodies specifically impeded cellular adhesion to the OPN fragments. Moreover, we show that the peptides used for immunization were able to induce antisera, which impeded adhesion either to all OPN forms, including the full-length form, or selectively to the corresponding truncated recombinant proteins. In conclusion, we developed immunological tools to selectively target functional properties of protease-cleaved OPN forms, which could find applications in treatment and prevention of various inflammatory diseases and cancers.
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- 2016
- Full Text
- View/download PDF
5. A phase I study assessing the safety, tolerability, immunogenicity, and low-density lipoprotein cholesterol-lowering activity of immunotherapeutics targeting PCSK9
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Zoe Oesterreicher, Beatrix Wulkersdorfer, Heimo Lagler, Gilles Lambert, Evelyn Berger-Sieczkowski, Christine Landlinger, Robert M. Mader, Robert M. Stoekenbroek, Gergana Galabova, Martin Bauer, Carsten Schwenke, Roman Reindl-Schwaighofer, Günther Staffler, Rossella Medori, Alexandra Kutzelnigg, Petra Lührs, and Markus Zeitlinger
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Adult ,Male ,myalgia ,medicine.medical_specialty ,Adolescent ,Active immunotherapy ,Hypercholesterolemia ,LDLc reduction ,030204 cardiovascular system & hematology ,Placebo ,Gastroenterology ,In vivo antibody development ,PCSK9 ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Humans ,Medicine ,Single-Blind Method ,Pharmacology (medical) ,030212 general & internal medicine ,Adverse effect ,Aged ,Pharmacology ,business.industry ,Immunogenicity ,General Medicine ,Middle Aged ,Clinical Trial ,Tolerability ,Vaccines, Subunit ,Cohort ,Peptide vaccine ,Female ,First-in-human study ,Proprotein Convertase 9 ,medicine.symptom ,business - Abstract
Purpose AT04A and AT06A are two AFFITOPE® peptide vaccine candidates being developed for the treatment of hypercholesterolemia by inducing proprotein convertase subtilisin/kexin type 9 (PCSK9)-specific antibodies. This study aimed to investigate safety, tolerability, antibody development, and reduction of low-density lipoprotein cholesterol (LDLc) following four subcutaneous immunizations. Methods This phase I, single-blind, randomized, placebo-controlled study was conducted in a total of 72 healthy subjects with a mean fasting LDLc level at baseline of 117.1 mg/dL (range 77–196 mg/dL). Each cohort enrolled 24 subjects to receive three priming immunizations at weeks 0, 4, and 8 and to receive a single booster immunization at week 60 of either AT04A, AT06A, or placebo. In addition to safety (primary objective), the antigenic peptide- and PCSK9-specific antibody response and the impact on LDLc were evaluated over a period of 90 weeks. Results The most common systemic treatment-related adverse events (AEs) reported were fatigue, headache, and myalgia in 75% of subjects in the AT06A group and 58% and 46% of subjects in the placebo and AT04A groups, respectively. Injection site reactions (ISR) representing 63% of all treatment-emergent adverse events (TEAEs), were transient and mostly of mild or moderate intensity and rarely severe (3%). Both active treatments triggered a robust, long-lasting antibody response towards the antigenic peptides used for immunization that optimally cross-reacted with the target epitope on PCSK9. In the AT04A group, a reduction in serum LDLc was observed with a mean peak reduction of 11.2% and 13.3% from baseline compared to placebo at week 20 and 70 respectively, and over the whole study period, the mean LDLc reduction for the AT04A group vs. placebo was −7.2% (95% CI [−10.4 to −3.9], P Conclusions Although both AT04A and AT06 were safe and immunogenic, only AT04A demonstrated significant LDLc-lowering activity, justifying further development. Trial registration EudraCT: 2015-001719-11. ClinicalTrials.gov Identifier: NCT02508896.
- Published
- 2021
6. Osteopontin affects macrophage polarization promoting endocytic but not inflammatory properties
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Nicole G. Grün, Karina Schuch, Katharina Ambroz, Alexandra Castelo-Rosa, Maximilian Zeyda, Thomas M. Stulnig, Bettina Wanko, Günther Staffler, Veronica Moreno-Viedma, and Lukas Leitner
- Subjects
0301 basic medicine ,Endocrinology, Diabetes and Metabolism ,medicine.medical_treatment ,Phagocytosis ,Macrophage polarization ,Medicine (miscellaneous) ,Adipose tissue ,Inflammation ,Proinflammatory cytokine ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,stomatognathic system ,medicine ,Osteopontin ,Nutrition and Dietetics ,biology ,Chemistry ,030104 developmental biology ,Cytokine ,030220 oncology & carcinogenesis ,Immunology ,biology.protein ,Cancer research ,Tumor necrosis factor alpha ,medicine.symptom - Abstract
Objective Macrophages are the main drivers of obesity-induced adipose tissue (AT) inflammation that causes insulin resistance. Macrophages polarize toward different inflammatory (M1) or protective (M2) phenotypes. Osteopontin (OPN) is an inflammatory cytokine highly expressed in AT in obesity and known to be involved in chronic inflammatory processes. It was hypothesized that OPN polarizes macrophages into a proinflammatory phenotype. Methods AT macrophages (ATMs) of OPN-deficient (Spp1−/−) and wild-type C57BL/6 (WT) mice with obesity and bone marrow-derived macrophages (BMDMs) of Spp1−/− and WT mice as well as human monocyte-derived macrophages (MDMs) polarized in the presence of OPN were investigated. Results While ATM infiltration was lower in Spp1−/− upon high-fat diet, Spp1−/− ATMs expressed more M1 and less M2 markers but less tumor necrosis factor-α compared with WT. There was no effect of OPN deficiency on BMDM polarization. In human MDMs, the presence of OPN during polarization ambiguously altered M1/M2-related marker expression and diminished LPS-induced inflammatory cytokine production. Strikingly, phagocytic activity was elevated by the presence of OPN during polarization in both human MDMs and murine BMDMs. Conclusions In contradiction to our hypothesis, data indicated that OPN does not induce inflammatory macrophages but was a signal to induce phagocytosis, which may be required due to increased adipocyte death in obesity.
- Published
- 2016
7. Antibody-mediated targeting of cleavage-specific OPN-T cell interactions
- Author
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Bettina Wanko, Matteo Tardelli, Alexander Jürets, Angelika Neuhofer, Gerhard Prager, John Morser, Lawrence L Leung, Günther Staffler, Maximilian Zeyda, and Thomas M Stulnig
- Subjects
Male ,Panniculitis ,Physiology ,T-Lymphocytes ,Gene Expression ,Pathology and Laboratory Medicine ,Biochemistry ,Mice ,White Blood Cells ,Animal Cells ,Immune Physiology ,Medicine and Health Sciences ,Immune Response ,Mice, Knockout ,Immune System Proteins ,T Cells ,Adipose Tissue ,Physiological Parameters ,Medicine ,Female ,Cellular Types ,Anatomy ,Research Article ,Cell Binding ,Cell Physiology ,Science ,CD8 Antigens ,Immune Cells ,Immunology ,Cytotoxic T cells ,CD5 Antigens ,Antibodies ,Signs and Symptoms ,stomatognathic system ,Diagnostic Medicine ,Genetics ,Animals ,Humans ,Obesity ,Inflammation ,Blood Cells ,Body Weight ,Antibody-Dependent Cell Cytotoxicity ,Biology and Life Sciences ,Proteins ,Cell Biology ,Biological Tissue ,Gene Expression Regulation ,Proteolysis ,Osteopontin - Abstract
T cells are crucial players in obesity-mediated adipose tissue inflammation. We hypothesized that osteopontin (OPN), an inflammatory protein with enhanced activity when proteolytically cleaved, affects the number of viable T cells in adipose tissue and assessed inhibition of the interaction between T cells and thrombin and matrix metalloproteinases-cleaved OPN using antibodies and postimmune sera. Gene expression of T cell markers in adipose tissue from wild-type (wt) and Spp1-/- (OPN deficient) mice was analyzed after 16 weeks of high fat diet (HFD) or low fat diet (LFD) feeding. CD3, CD8 and OPN gene expression in omental adipose tissue from individuals with obesity was measured. OPN-T cell interactions were assessed with a fluorescence-based adhesion assay and blocked with antibodies targeting OPN. Comparison of T cell gene expression in adipose tissue from wt and Spp1-/- mice showed that OPN affected the number of T cells while in humans, levels of OPN correlated with T cell markers in omental adipose tissue. The interaction between T cells and cleaved OPN was blocked by postimmune sera following OPN peptide vaccinations and with monoclonal antibodies. In conclusion, levels of OPN affected the number of T cells in obesity and antibodies against cleaved OPN antagonize OPN-T cell interactions.
- Published
- 2018
8. Immunological blockade of adipocyte inflammation caused by increased matrix metalloproteinase-cleaved osteopontin in obesity
- Author
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Maike Keck, Lukas Leitner, Maximilian Zeyda, Günther Staffler, Thomas M. Stulnig, Alexander Jürets, Bianca K. Itariu, Viktor Grablowitz, Gerhard Prager, Karina Schuch, and Oskar C. Aszmann
- Subjects
medicine.medical_specialty ,Nutrition and Dietetics ,biology ,Chemistry ,Endocrinology, Diabetes and Metabolism ,Insulin ,medicine.medical_treatment ,Medicine (miscellaneous) ,Adipose tissue ,Inflammation ,Matrix metalloproteinase ,medicine.disease ,chemistry.chemical_compound ,Endocrinology ,Insulin resistance ,stomatognathic system ,Downregulation and upregulation ,Internal medicine ,Adipocyte ,medicine ,biology.protein ,Osteopontin ,medicine.symptom - Abstract
Objective Osteopontin (OPN) is upregulated in adipose tissue (AT) in obesity and contributes to subclinical inflammation, adipocyte dysfunction, and insulin resistance. OPN effects can be increased by cleavage by matrix metalloproteinases (MMP). This study aimed at investigating the presence of OPN cleavage products in human AT in obesity and their impact on adipocyte function and immunological blockade of these effects. Methods AT of severely obese and control donors was investigated for OPN and MMP expression and the presence of OPN cleavage fragments. Primary adipocytes were isolated from human donors for in vitro investigation of cleaved OPN effects. Results OPN and MMP-9 expression was highly correlated in AT from obese donors, and increased levels of cleaved OPN were detected in AT from obese individuals. The in vitro effect of OPN on adipocyte inflammation and insulin resistance was enhanced by protease cleavage, which could finally be blocked with a monoclonal antibody directed against the MMP cleavage site of OPN. Conclusions These findings show that MMP cleavage of OPN in AT occurs in obesity, thereby enhancing OPN's inflammatory and pro-diabetic activity on adipocytes. Specifically targeting MMP-cleaved OPN opens avenues for prevention and treatment of obesity-induced type 2 diabetes.
- Published
- 2015
9. Peptide-based vaccination against OPN integrin binding sites does not improve cardio-metabolic disease in mice
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Lukas Leitner, Maximilian Zeyda, Günther Staffler, Marie Le Bras, Karina Zeyda, Christine Landlinger, Nicole G. Grün, Bettina Wanko, Thomas M. Stulnig, Karin Strohmeier, and Veronica Moreno-Viedma
- Subjects
0301 basic medicine ,Male ,Integrins ,Heart Diseases ,medicine.medical_treatment ,Immunology ,Adipose tissue ,Inflammation ,030204 cardiovascular system & hematology ,Cross Reactions ,Article ,Antibodies ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Thrombin ,Insulin resistance ,stomatognathic system ,Metabolic Diseases ,medicine ,Immunology and Allergy ,Macrophage ,Animals ,Osteopontin ,Obesity ,Integrin binding ,Mice, Knockout ,Binding Sites ,biology ,medicine.disease ,Atherosclerosis ,Peptide Fragments ,Disease Models, Animal ,030104 developmental biology ,Cytokine ,Receptors, LDL ,biology.protein ,Immunization ,medicine.symptom ,Insulin Resistance ,Biomarkers ,medicine.drug ,Protein Binding - Abstract
Obesity causes insulin resistance via a chronic low-grade inflammation. This inflammation is characterized by elevated pro-inflammatory markers and macrophage accumulation in the adipose tissue (AT). AT inflammation is a key factor causing insulin resistance and thus type 2 diabetes, both linked to atherosclerotic cardiovascular disease. Osteopontin (OPN), a well-known inflammatory cytokine, is involved in obesity-linked complications including AT inflammation, insulin resistance, atherosclerosis and CVD. During inflammation, OPN is proteolytically cleaved by matrix metalloproteinases or thrombin leading to increased OPN activity. Therefore, OPN provides a new interesting target for immunological prevention and treatment of obesity-associated diseases. The aim of our study was to evaluate peptide-based vaccines against integrin binding sites of OPN and to examine whether these active immunotherapies are functional in reducing metabolic tissue inflammation, insulin resistance, and atherosclerosis in a cardio-metabolic (Ldlr(−/−) mice) and a diet-induced obesity model (WT mice). However, atherosclerosis, insulin resistance and AT inflammation were not diminished after treatment with OPN-derived peptides in murine models. Lack of efficacy was based on a failure to induce antibodies capable to bind epitopes in the context of functional OPN protein. In conclusion, our data point to unexpected challenges in the immunotherapeutic targeting of adhesive motives, such as RGD containing sequences, on endogenous proteins.
- Published
- 2016
10. Inhibition of Cellular Adhesion by Immunological Targeting of Osteopontin Neoepitopes Generated through Matrix Metalloproteinase and Thrombin Cleavage
- Author
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Günther Staffler, Alexander Jürets, Lukas Leitner, Marie Le Bras, Edvin Turkof, Thomas M. Stulnig, Matteo Tardelli, Angelika Neuhofer, Gesine Stein, and Maximilian Zeyda
- Subjects
0301 basic medicine ,Integrins ,Physiology ,lcsh:Medicine ,Matrix metalloproteinase ,Biochemistry ,Antibodies, Monoclonal, Murine-Derived ,Epitopes ,Mice ,0302 clinical medicine ,Immune Physiology ,Medicine and Health Sciences ,Osteopontin ,Enzyme-Linked Immunoassays ,lcsh:Science ,Multidisciplinary ,Immune System Proteins ,biology ,Thrombin ,Hematology ,Recombinant Proteins ,Extracellular Matrix ,Body Fluids ,Blood ,Gelatinases ,030220 oncology & carcinogenesis ,Cell lines ,Cellular Structures and Organelles ,Anatomy ,Biological cultures ,medicine.drug ,Research Article ,Cell Binding ,Cell Physiology ,medicine.drug_class ,Integrin ,Immunology ,Monoclonal antibody ,Antibodies ,03 medical and health sciences ,stomatognathic system ,medicine ,Cell Adhesion ,Animals ,Humans ,Cell adhesion ,Immunoassays ,Integrin binding ,lcsh:R ,HEK 293 cells ,Biology and Life Sciences ,Proteins ,Cell Biology ,Blood Serum ,Molecular biology ,Research and analysis methods ,030104 developmental biology ,HEK293 Cells ,Proteolysis ,biology.protein ,Immunologic Techniques ,lcsh:Q ,Immune Serum - Abstract
Osteopontin (OPN), a secreted protein involved in inflammatory processes and cancer, induces cell adhesion, migration, and activation of inflammatory pathways in various cell types. Cells bind OPN via integrins at a canonical RGD region in the full length form as well as to a contiguous cryptic site that some have shown is unmasked upon thrombin or matrix metalloproteinase cleavage. Thus, the adhesive capacity of osteopontin is enhanced by proteolytic cleavage that may occur in inflammatory conditions such as obesity, atherosclerosis, rheumatoid arthritis, tumor growth and metastasis. Our aim was to inhibit cellular adhesion to recombinant truncated proteins that correspond to the N-terminal cleavage products of thrombin- or matrix metalloproteinase-cleaved OPN in vitro. We specifically targeted the cryptic integrin binding site with monoclonal antibodies and antisera induced by peptide immunization of mice. HEK 293 cells adhered markedly stronger to truncated OPN proteins than to full length OPN. Without affecting cell binding to the full length form, the raised monoclonal antibodies specifically impeded cellular adhesion to the OPN fragments. Moreover, we show that the peptides used for immunization were able to induce antisera, which impeded adhesion either to all OPN forms, including the full-length form, or selectively to the corresponding truncated recombinant proteins. In conclusion, we developed immunological tools to selectively target functional properties of protease-cleaved OPN forms, which could find applications in treatment and prevention of various inflammatory diseases and cancers.
- Published
- 2016
11. Osteopontin affects macrophage polarization promoting endocytic but not inflammatory properties
- Author
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Karina, Schuch, Bettina, Wanko, Katharina, Ambroz, Alexandra, Castelo-Rosa, Verónica, Moreno-Viedma, Nicole G, Grün, Lukas, Leitner, Günther, Staffler, Maximilian, Zeyda, and Thomas M, Stulnig
- Subjects
Inflammation ,Male ,Tumor Necrosis Factor-alpha ,Macrophages ,Diet, High-Fat ,Mice, Inbred C57BL ,Mice ,Phenotype ,Adipose Tissue ,Phagocytosis ,Adipocytes ,Animals ,Osteopontin ,Obesity ,Insulin Resistance - Abstract
Macrophages are the main drivers of obesity-induced adipose tissue (AT) inflammation that causes insulin resistance. Macrophages polarize toward different inflammatory (M1) or protective (M2) phenotypes. Osteopontin (OPN) is an inflammatory cytokine highly expressed in AT in obesity and known to be involved in chronic inflammatory processes. It was hypothesized that OPN polarizes macrophages into a proinflammatory phenotype.AT macrophages (ATMs) of OPN-deficient (Spp1(-/-) ) and wild-type C57BL/6 (WT) mice with obesity and bone marrow-derived macrophages (BMDMs) of Spp1(-/-) and WT mice as well as human monocyte-derived macrophages (MDMs) polarized in the presence of OPN were investigated.While ATM infiltration was lower in Spp1(-/-) upon high-fat diet, Spp1(-/-) ATMs expressed more M1 and less M2 markers but less tumor necrosis factor-α compared with WT. There was no effect of OPN deficiency on BMDM polarization. In human MDMs, the presence of OPN during polarization ambiguously altered M1/M2-related marker expression and diminished LPS-induced inflammatory cytokine production. Strikingly, phagocytic activity was elevated by the presence of OPN during polarization in both human MDMs and murine BMDMs.In contradiction to our hypothesis, data indicated that OPN does not induce inflammatory macrophages but was a signal to induce phagocytosis, which may be required due to increased adipocyte death in obesity.
- Published
- 2015
12. Immunological blockade of adipocyte inflammation caused by increased matrix metalloproteinase-cleaved osteopontin in obesity
- Author
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Lukas, Leitner, Karina, Schuch, Alexander, Jürets, Bianca K, Itariu, Maike, Keck, Viktor, Grablowitz, Oskar C, Aszmann, Gerhard, Prager, Günther, Staffler, Maximilian, Zeyda, and Thomas M, Stulnig
- Subjects
Adipose Tissue ,Matrix Metalloproteinase 9 ,Adipocytes ,Humans ,Osteopontin ,Obesity ,Insulin Resistance - Abstract
Osteopontin (OPN) is upregulated in adipose tissue (AT) in obesity and contributes to subclinical inflammation, adipocyte dysfunction, and insulin resistance. OPN effects can be increased by cleavage by matrix metalloproteinases (MMP). This study aimed at investigating the presence of OPN cleavage products in human AT in obesity and their impact on adipocyte function and immunological blockade of these effects.AT of severely obese and control donors was investigated for OPN and MMP expression and the presence of OPN cleavage fragments. Primary adipocytes were isolated from human donors for in vitro investigation of cleaved OPN effects.OPN and MMP-9 expression was highly correlated in AT from obese donors, and increased levels of cleaved OPN were detected in AT from obese individuals. The in vitro effect of OPN on adipocyte inflammation and insulin resistance was enhanced by protease cleavage, which could finally be blocked with a monoclonal antibody directed against the MMP cleavage site of OPN.These findings show that MMP cleavage of OPN in AT occurs in obesity, thereby enhancing OPN's inflammatory and pro-diabetic activity on adipocytes. Specifically targeting MMP-cleaved OPN opens avenues for prevention and treatment of obesity-induced type 2 diabetes.
- Published
- 2014
13. A humanized osteopontin mouse model and its application in immunometabolic obesity studies
- Author
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Thomas M. Stulnig, Günther Staffler, Veronica Moreno-Viedma, Karin Strohmeier, Maximilian Zeyda, Karina Zeyda, and Nicole G. Grün
- Subjects
Blood Glucose ,Male ,0301 basic medicine ,medicine.medical_specialty ,Genotype ,Transgene ,Adipose tissue ,Mice, Transgenic ,Inflammation ,Diet, High-Fat ,Proinflammatory cytokine ,03 medical and health sciences ,0302 clinical medicine ,Insulin resistance ,stomatognathic system ,Physiology (medical) ,Internal medicine ,Adipocytes ,medicine ,Animals ,Humans ,Amino Acid Sequence ,Obesity ,Osteopontin ,Homologous Recombination ,biology ,Body Weight ,Biochemistry (medical) ,CD44 ,Insulin tolerance test ,Public Health, Environmental and Occupational Health ,Hypertrophy ,General Medicine ,medicine.disease ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,Endocrinology ,Adipose Tissue ,Gene Expression Regulation ,Liver ,030220 oncology & carcinogenesis ,biology.protein ,Insulin Resistance ,medicine.symptom - Abstract
Osteopontin (OPN) is a multifunctional protein involved in several inflammatory processes and pathogeneses including obesity-related disorders and cancer. OPN binds to a variety of integrin receptors and CD44 resulting in a proinflammatory stimulus. Therefore, OPN constitutes a novel interesting target to develop new therapeutic strategies, which counteract OPN's proinflammatory properties. We established a humanized SPP1 (hSPP1) mouse model and evaluated its suitability as a model for obesity and insulin resistance. Unchallenged hSPP1 animals did not significantly differ in body weight and gross behavioral properties compared to wild-type (WT) animals. High-fat diet-challenged hSPP1 similarly developed obesity and inflammation, whereas insulin resistance was markedly changed. However, OPN expression profile in tissues was significantly altered in hSPP1 compared to WT depending on the diet. In conclusion, we developed a versatile humanized model to study the action of OPN in vivo and to develop strategies that target human OPN in a variety of pathologies.
- Published
- 2016
14. SUPPRESSION OF PRIMARY T-CELL RESPONSES AND INDUCTION OF ALLOANTIGEN-SPECIFIC HYPORESPONSIVENESS IN VITRO BY THE JANUS KINASE INHIBITOR TYRPHOSTIN AG4901
- Author
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Marcus D. Säemann, Walter H. Hörl, Georg A. Böhmig, Hannes Stockinger, Christos Diakos, Günther Staffler, Peter-Michael Krieger, Gerhard J. Zlabinger, and Christoph H. Österreicher
- Subjects
Transplantation ,Janus kinase 3 ,T cell ,CD28 ,Tyrosine phosphorylation ,Biology ,Molecular biology ,Cell biology ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,medicine ,Cytokine secretion ,IL-2 receptor ,Janus kinase ,Cytokine receptor - Abstract
BACKGROUND Tyrphostin AG490 has recently been shown to block interleukin (IL)-2 receptor gamma-chain-associated Janus kinase 3. Here, we analyzed the effect of AG490 on T-cell alloresponses in vitro. METHODS For the evaluation of T-cell activation, DNA synthesis, surface marker expression, cytokine secretion, intracellular calcium mobilization, early protein tyrosine phosphorylation, and apoptosis were measured. RESULTS AG490 effectively inhibited T-cell proliferation in human mixed lymphocyte culture (MLC) even when added 4 days after culture initiation. Inhibition of IL-2-dependent proliferation in T-cell blasts and the incapability of IL-2 or IL-15 to restore proliferation in AG490-treated MLC suggests interference with cytokine receptor signaling. T-cell receptor-triggered early protein tyrosine phosphorylation, calcium mobilization, up-regulation of CD69, and initial CD25 expression were not affected. Interestingly, AG490 substantially inhibited production of IL-2 and interferon-gamma in T cells stimulated with alloantigen or via CD3 and CD28. In CD28-independent activation models (e.g., stimulation with phorbol myristate acetate plus ionomycin), however, cytokine secretion was not inhibited. Pretreatment of primary MLC with AG490 resulted in substantial down-regulation of secondary responses to cells from the original donor as opposed to third-party cells or phytohemagglutinin. Unresponsiveness was induced also in T cells stimulated with CD3 monoclonal antibody. Induction of apoptosis in polyclonally activated T cells and the incapability of IL-2 to reverse specific hyporesponsiveness, suggest programmed cell death as an important mechanism underlying antigen-specific down-regulation of alloresponses. CONCLUSIONS We demonstrate that AG490 blocks different manifestations of T-cell activation. This and its ability to induce alloantigen-specific hyporesponsiveness point to a potential use for interfering with alloreactivities in vivo.
- Published
- 2000
15. Analysis of the early biogenesis of CD1b: involvement of the chaperones calnexin and calreticulin, the proteasome and β2-microglobulin
- Author
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Otto Majdic, Günther Staffler, Robert Hüttinger, and Hannes Stockinger
- Subjects
Proteasome Endopeptidase Complex ,Calnexin ,Immunology ,Antigen presentation ,CD1 ,Biology ,Transfection ,Monocytes ,Cell Line ,Antigens, CD1 ,Antigens, CD ,Multienzyme Complexes ,Mannosidases ,MHC class I ,Humans ,Immunology and Allergy ,Antigen processing ,beta-Glucosidase ,Calcium-Binding Proteins ,Histocompatibility Antigens Class I ,Indolizines ,General Medicine ,Transporter associated with antigen processing ,Cell biology ,Cysteine Endopeptidases ,Ribonucleoproteins ,Chaperone (protein) ,biology.protein ,Calreticulin ,beta 2-Microglobulin ,Molecular Chaperones - Abstract
beta(2)-Microglobulin (beta(2)m)-associated human CD1b proteins present lipid and glycolipid antigens, which are loaded on CD1b in endosomal compartments. In contrast, the related MHC class I molecules acquire antigenic peptides in the endoplasmic reticulum. Here, we investigated the biogenesis of CD1b before beta(2)m binding in comparison to MHC class I. In beta(2)m-deficient FO-1 cells, we found CD1b heavy chains (HC) complexed with the chaperones calnexin and calreticulin, while MHC class I HC associated only with calnexin. Despite this difference, both CD1b HC and MHC class I HC were degraded when the chaperone interactions were prevented by the glucosidase inhibitor castanospermine. The degradation of both molecules included the proteasome and mannosidases. Chaperone-unassociated CD1b could be rescued from degradation by supplementing FO-1 cells with beta(2)m. Finally, prevention of chaperone interaction significantly reduced neoexpression of CD1b upon differentiation of monocytes to dendritic cells, underlining the importance of chaperones for proper expression of CD1b under physiological conditions.
- Published
- 1999
16. Vascular–Endothelial Cadherin (CD144)– but Not PECAM–1 (CD31)–Based Cell–to–Cell Contacts Convey the Maintenance of a Quiescent Endothelial Monolayer
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Klaus Wolff, Susanne Hoch, Günther Staffler, Thomas Halama, Peter Petzelbauer, and Hannes Stockinger
- Subjects
Endothelium ,Blotting, Western ,Immunology ,Fluorescent Antibody Technique ,Cell Communication ,Biology ,Transfection ,Cell junction ,Cell Line ,Adherens junction ,Cell–cell interaction ,Antigens, CD ,medicine ,Humans ,Immunology and Allergy ,Microscopy, Confocal ,Dose-Response Relationship, Drug ,Cell adhesion molecule ,Cadherin ,General Medicine ,Cadherins ,Flow Cytometry ,Precipitin Tests ,Cell biology ,Platelet Endothelial Cell Adhesion Molecule-1 ,Endothelial stem cell ,medicine.anatomical_structure ,Endothelium, Vascular ,VE-cadherin ,Cell Division - Abstract
Background: In vivo, all blood vessels are lined by a single layer of flattened noncycling endothelial cells. We tested the hypothesis that the maintenance of such a quiescent endothelial monolayer depends on homotypic contacts between not yet defined growth–inhibitory molecules located at interendothelial junctions. Methods: ECV304 cells, which lack endogenous vascular endothelial cadherin (VE cadherin) or CD31 expression, were transfected with cDNA encoding for the respective proteins or with the empty vector. Results: In VE cadherin transfectants, β–catenin was targeted to junctional regions and the F–actin–based cytoskeleton formed parallel bundles reaching from one cell border to the other. In contrast, in CD31 transfectants and in empty vector cells, β–catenin was dispersed throughout the cytoplasm, and F–actin formed short, plump and criss–cross bundles. On a two–dimensional plastic matrix, both, VE cadherin and CD31 transfectants formed clusters of polygonal cells, whereas in three–dimensional gels, only VE cadherin cells were able to form tubes. Empty vector cells grew in a fibroblast–like pattern and neither formed clusters nor tubes. Most importantly, whereas CD31 and empty vector cells grew on top of each other, formed polylayers and maintained cycling even after reaching confluence, VE cadherin cells strictly maintained a single layer of flattened cells and the numbers of cycling cells dramatically dropped after reaching a continuous monolayer. Conclusion: The insertion of VE cadherin into ECV304 cells produces a cell type which mimics endothelial growth characteristics seen in vivo.
- Published
- 1999
17. Analysis of the requirement for β2-microglobulin for expression and formation of human CD1 antigens
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Walter Schmidt, Anton Bauer, Hannes Stockinger, Otto Majdic, Walter Knapp, Robert Hüttinger, C Hansmann, and Günther Staffler
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Recombinant Fusion Proteins ,Immunology ,Antigen presentation ,CD1 ,chemical and pharmacologic phenomena ,Kidney ,Major histocompatibility complex ,complex mixtures ,Cell Line ,law.invention ,Antigens, CD1 ,Antigen ,law ,MHC class I ,Tumor Cells, Cultured ,Humans ,Immunology and Allergy ,Secretion ,Melanoma ,biology ,Beta-2 microglobulin ,Cell Membrane ,Antibodies, Monoclonal ,Biological Transport ,hemic and immune systems ,Molecular biology ,Cell biology ,Solubility ,biology.protein ,Recombinant DNA ,lipids (amino acids, peptides, and proteins) ,beta 2-Microglobulin - Abstract
Human CD1 form a group of nonpolymorphic leukocyte surface molecules with homology to major histocompatibility complex (MHC) proteins. Recent findings in human and in mouse demonstrate the capacity of CD1 molecules to present nonpeptide components like lipids or lipoglycans as well as peptides. We studied the involvement of beta 2-microglobulin (beta 2m) in expression of the classic human CD1 proteins CD1a, CD1b, and CD1c. The beta 2m-deficient human melanoma cell line FO-1 was transiently transfected with either CD1a, CD1b, or CD1c DNA alone, or in combination with beta 2m using the adenovirus-enhanced receptor-mediated transfer infection system. Only co-transfection of FO-1 cells with CD1+ beta 2m resulted in the detection of CD1 Ag by monoclonal antibodies (mAb). This indicated that CD1 mAb recognized determinants are dependent on beta 2m and raised the question whether beta 2m-free forms of CD1 can be expressed. Therefore, to visualize CD1 molecule expression independently of beta 2m, we expressed tagged recombinant forms. A full-length CD1b construct tagged at the very C terminus with a small peptide was transported to the plasma membrane only when beta 2m was co-transfected. beta 2m involvement in the transport of CD1 was confirmed by expression of soluble forms of CD1a, CD1b, and CD1c in three different cell types. Analogous to tagged full-length CD1b, secretion of the soluble CD1 constructs was strictly dependent on beta 2m. The soluble CD1 chimeras were secreted as complexes with endogenous beta 2m. Thus, similar to its role for MHC class I expression, beta 2m is essential for processing and surface transport of the classic human CD1 molecules CD1a, CD1b, and CD1c.
- Published
- 1997
18. Tamm-Horsfall glycoprotein links innate immune cell activation with adaptive immunity via a Toll-like receptor-4–dependent mechanism
- Author
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Marcus D. Säemann, Thomas Weichhart, Maximilian Zeyda, Günther Staffler, Michael Schunn, Karl M. Stuhlmeier, Yuri Sobanov, Thomas M. Stulnig, Shizuo Akira, Alexander von Gabain, Uwe von Ahsen, Walter H. Hörl, and Gerhard J. Zlabinger
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Bone Marrow Cells ,Receptors, Cell Surface ,Kidney ,Article ,Mice ,Mucoproteins ,Uromodulin ,Animals ,Humans ,Inflammation ,Mice, Knockout ,Tumor Necrosis Factor-alpha ,Macrophages ,NF-kappa B ,hemic and immune systems ,Cell Differentiation ,General Medicine ,Dendritic Cells ,Immunity, Innate ,Toll-Like Receptor 2 ,DNA-Binding Proteins ,Toll-Like Receptor 4 ,Gene Expression Regulation ,Toll-Like Receptor 9 ,Urinary Tract Infections ,lipids (amino acids, peptides, and proteins) ,Signal Transduction - Abstract
Tamm-Horsfall glycoprotein (THP) is expressed exclusively in the kidney and constitutes the most abundant protein in mammalian urine. A critical role for THP in antibacterial host defense and inflammatory disorders of the urogenital tract has been suggested. We demonstrate that THP activates myeloid DCs via Toll-like receptor-4 (TLR4) to acquire a fully mature DC phenotype. THP triggers typical TLR signaling, culminating in activation of NF-kappaB. Bone marrow-derived macrophages from TLR4- and MyD88-deficient mice were nonresponsive to THP in contrast to those from TLR2- and TLR9-deficient mice. In vivo THP-driven TNF-alpha production was evident in WT but not in Tlr4-/- mice. Importantly, generation of THP-specific Abs consistently detectable in urinary tract inflammation was completely blunted in Tlr4-/- mice. These data show that THP is a regulatory factor of innate and adaptive immunity and therefore could have significant impact on host immunity in the urinary tract.
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- 2005
19. Identification of human CD93 as the phagocytic C1q receptor (C1qRp) by expression cloning
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Stefan Wille, Peter Steinberger, Günther Staffler, Andreas Szekeres, Otto Madic, Walter Knapp, Hannes Stockinger, Nicole Selenko, Elisabeth Prager, and Johannes Stöckl
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DNA, Complementary ,Phagocytosis ,Sialoglycoproteins ,Immunology ,Molecular Sequence Data ,Biology ,Mitochondrial Proteins ,Mice ,Antigen ,Antigens, CD ,Complementary DNA ,Tumor Cells, Cultured ,Immunology and Allergy ,Animals ,Humans ,Amino Acid Sequence ,Cloning, Molecular ,Receptor ,CD93 ,Peptide sequence ,Cloning ,Mice, Inbred BALB C ,Phagocytes ,Membrane Glycoproteins ,Base Sequence ,Cell Biology ,Dendritic Cells ,Molecular biology ,Cell biology ,Receptors, Complement ,Hyaluronan Receptors ,Expression cloning ,Carrier Proteins - Abstract
CD93 is a ∼120 kDa O-sialoglycoprotein that within the hematopoietic system is selectively expressed on cells of the myeloid lineage. So far, its primary structure and function were unknown. We used retroviral-expression cloning to isolate the CD93 cDNA. Sequence analysis revealed that CD93 is identical to a protein on human phagocytes termed C1q receptor (C1qRp). C1qRp was shown previously to mediate enhancement of phagocytosis in monocytes and was suggested to be a receptor of C1q and two other structurally related molecules. When studying CD93 transductants and control cells, we found that cells expressing CD93 have enhanced capacity to bind C1q. Furthermore, we show that immature dendritic cells (DC) express CD93/C1qRp, and mature DC, known to have reduced capacity for antigen uptake and to have lost the ability to phagocytose, show weak-to-negative CD93/C1qRp expression.
- Published
- 2002
20. Characterization of CDw92 as a member of the choline transporter-like protein family regulated specifically on dendritic cells
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Helmut Burtscher, Thomas Baumruker, Gerhard J. Zlabinger, Andreas Szekeres, Hannes Stockinger, Johannes Stöckl, Stefan Wille, Eva E. Prieschl, Otto Majdic, Günther Staffler, Walter Knapp, Duangkamol Kunthalert, and Elisabeth Prager
- Subjects
Protein family ,Sequence analysis ,Immunology ,Molecular Sequence Data ,CD2 Antigens ,Biology ,Cell Line ,Mice ,Complementary DNA ,Sequence Homology, Nucleic Acid ,Tumor Cells, Cultured ,Immunology and Allergy ,Animals ,Humans ,Amino Acid Sequence ,Tyrosine ,Cloning, Molecular ,Cells, Cultured ,Base Sequence ,Sequence Homology, Amino Acid ,CLEC7A ,Antibodies, Monoclonal ,Membrane Transport Proteins ,Cell Differentiation ,Dendritic Cells ,Molecular biology ,Precipitin Tests ,Choline transporter ,Transmembrane domain ,Expression cloning ,Cytokines - Abstract
CDw92 is a 70-kDa surface protein broadly expressed on leukocytes and endothelial cells. In this manuscript, we present the molecular cloning of the CDw92 molecule by using a highly efficient retroviral expression cloning system. Sequence analysis of the CDw92 cDNA revealed a length of 2679 bp. The 1959-bp open reading frame encodes a protein of 652 amino acids. Computational analysis of the CDw92 protein sequence indicates 10 transmembrane domains, three potential N-linked glycosylation sites, and an amino acid stretch in the C-terminal region that is related to the immunoreceptor tyrosine-based inhibitory motif. Comparison of the sequence of the CDw92 clone presented in this study with various database entries show that it is a C-terminal variant of human choline transporter-like protein 1, a member of a recently identified family of multitransmembrane surface proteins. Furthermore, we found that CDw92 is stably expressed on monocytes, PBLs, and endothelial cells, as we did not yet find modulation of expression by various stimuli on these cells. In contrast to this factor-independent expression of CDw92, we detected a specific regulation of CDw92 on monocyte-derived dendritic cells (Mo-DCs). Maturation of Mo-DCs by ionomycin or calcium ionophore resulted in down-regulation of CDw92 and incubation of these cells with IL-10 in a specific re-expression. Moreover, targeting of CDw92 on LPS-treated Mo-DCs by CDw92 mAb VIM15b augmented the LPS-induced IL-10 production 2.8-fold. Together, these data suggest a crucial role of the CDw92 protein in the biology and regulation of the function of leukocytes in particular DCs.
- Published
- 2001
21. Platelet endothelial cell adhesion molecule-1 and vascular endothelial cadherin cooperatively regulate fibroblast growth factor-induced modulations of adherens junction functions
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Günther Staffler, Klaus Wolff, Manuela Pillinger, Elisabeth Prager, Peter Petzelbauer, Thomas Halama, Marion Gröger, Wolfgang Holnthoner, Sonja Lechleitner, and Hannes Stockinger
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Blood Platelets ,Basic fibroblast growth factor ,Dermatology ,Biology ,Vascular endothelial growth inhibitor ,Biochemistry ,Translocation, Genetic ,chemistry.chemical_compound ,Vasculogenesis ,transmigration ,Molecular Biology ,beta Catenin ,Cadherin ,Fibroblast growth factor receptor 2 ,Cell Biology ,Adherens Junctions ,β-catenin ,Cadherins ,Cell biology ,Vascular endothelial growth factor B ,Fibroblast Growth Factors ,Vascular endothelial growth factor A ,Cytoskeletal Proteins ,chemistry ,Vascular endothelial growth factor C ,Trans-Activators ,CD31 ,CD144 ,Endothelium, Vascular ,actin ,Cell Adhesion Molecules - Abstract
Cellular adherens junctions are formed by cadherins linked to proteins of the catenin family. In endothelial cells, not only vascular endothelial cadherin but also platelet endothelial cell adhesion molecule-1 localizes into junctions and associates with beta-catenin. To explore a putative cooperation of platelet endothelial cell adhesion molecule-1 and vascular endothelial cadherin, we analyzed transfectants expressing either platelet endothelial cell adhesion (CD31 cells) or vascular endothelial cadherin (CD144 cells) or both molecules (CD31/CD144 cells), and, for comparison, human umbilical vein endothelial cells. Basic fibroblast growth factor completely dissociated vascular endothelial cadherin/beta-catenin complexes and robustly moved beta-catenin into the nucleus in CD144 cells, whereas in CD31/CD144 cells as well as in human umbilical vein endothelial cells, fibroblast growth factor only partially dissociated the junctional complex followed by a significantly reduced nuclear translocation of beta-catenin. In contrast, in CD31 cells, the subcellular distribution of beta-catenin remained unaffected by fibroblast growth factor. As a functional consequence, fibroblast growth factor induced a complete collapse of the F-actin network in CD144 cells, a limited rearrangement of F-actin fibers in CD31/CD144 cells and no F-actin rearrangement in CD31 cells. We also analyzed the effect of fibroblast growth factor-induced rearrangement of junctions on junction permeability for leukocytes: in line with our observation that vascular endothelial cadherin was required for cells to respond to fibroblast growth factor, only in CD31/CD144 cells, but not in CD31 cells, leukocyte transmigration was significantly enhanced by fibroblast growth factor. In conclusion platelet endothelial cell adhesion molecule-1 cooperates with vascular endothelial cadherin in a mutual fashion; platelet endothelial cell adhesion molecule-1 reduces and temporarily limits fibroblast growth factor-induced dissociation of vascular endothelial cadherin/beta-catenin complexes, but requires vascular endothelial cadherin to control leukocyte transmigration in dependence of fibroblast growth factor.
- Published
- 2001
22. Immunoregulation in Urinary Tract Inflammation—A Role of Tamm-Horsfall Glycoprotein
- Author
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Gerhard J. Zlabinger, Shizuo Akira, U von Ahsen, Thomas M. Stulnig, Säemann, Michael Schunn, Maximilian Zeyda, A von Gabain, Günther Staffler, Thomas Weichhart, Walter H. Hörl, Yuri Sobanov, and Karl M. Stuhlmeier
- Subjects
Toll-like receptor ,Innate immune system ,Urinary system ,Normal urine ,Inflammation ,General Medicine ,Biology ,Acquired immune system ,Nephrology ,Tamm-Horsfall glycoprotein ,Immunology ,medicine ,medicine.symptom ,Cell activation - Abstract
The Tamm-Horsfall protein (THP), the most abundant protein in normal urine, was discovered five decades ago ([1][1]), or possibly even much earlier ([2][2]), but the role for the most abundant protein in normal urine had remained enigmatic for a long time. It is expressed in the thick ascending limb
- Published
- 2005
23. Selective inhibition of T cell activation via CD147 through novel modulation of lipid rafts
- Author
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Gerhard J. Zlabinger, Andreas Szekeres, Günther Staffler, Maximilian Zeyda, Marcus D. Säemann, Karel Drbal, Gerhard J. Schütz, Elisabeth Prager, Thomas M. Stulnig, and Hannes Stockinger
- Subjects
endocrine system ,Cell signaling ,Isoantigens ,Transcription, Genetic ,T cell ,T-Lymphocytes ,Immunology ,Down-Regulation ,Cell Separation ,Biology ,Lymphocyte Activation ,Avian Proteins ,Membrane Microdomains ,CD28 Antigens ,Antigens, CD ,Antigens, Neoplasm ,medicine ,Immunology and Allergy ,Humans ,IL-2 receptor ,Immunologic Capping ,Phosphorylation ,Receptors, Cytokine ,Receptor ,Phosphotyrosine ,Lipid raft ,Cells, Cultured ,Membrane Glycoproteins ,T-cell receptor ,Antibodies, Monoclonal ,CD48 ,Blood Proteins ,Cell biology ,medicine.anatomical_structure ,Receptor-CD3 Complex, Antigen, T-Cell ,Antigens, Surface ,Basigin ,Cytokines ,Interleukin-2 ,Signal transduction ,Lymphocyte Culture Test, Mixed ,Cell Division ,Muromonab-CD3 ,Signal Transduction - Abstract
The plasma membrane is compartmentalized into microdomains and the association/dissociation of receptors and signaling molecules with/from these membrane domains is a major principle for regulation of signal transduction. By following the reorganization of microdomains on living cells and performing biochemical studies, we show that Ab targeting of the T cell activation-associated Ag CD147 prevents TCR stimulation-dependent reorganization and clustering of microdomains. Triggering CD147 induces a displacement of the GPI-anchored coreceptors CD48 and CD59 from microdomains in human T lymphocytes. This perturbation of microdomains is accompanied by a selective inhibition of TCR-mediated T cell proliferation. The CD147-inhibited cells secret normal levels of IL-2 but acquire reduced amounts of the IL-2 receptor α-chain CD25. These results indicate that negative regulating signals can modulate microdomains and suggest a general mechanism for inhibition of receptor signaling.
24. An accelerated mouse model for atherosclerosis and adipose tissue inflammation
- Author
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Maximilian Zeyda, Nicole G Sommer, Alisina Sarabi, Thomas M. Stulnig, Angelika Neuhofer, Lukas Leitner, Günther Staffler, and Bernhard Wernly
- Subjects
Male ,Time Factors ,Endocrinology, Diabetes and Metabolism ,Adipose tissue ,Inflammation ,Disease ,Type 2 diabetes ,Mice ,Insulin resistance ,Dietary Sucrose ,Diabetes mellitus ,medicine ,Animals ,Adipose tissue inflammation ,Glucose intolerance ,Sucrose-enrichment ,Mice, Knockout ,business.industry ,Cardio-metabolic disease ,Diet-induced obesity ,Methodology ,medicine.disease ,Atherosclerosis ,Obesity ,Metabolic syndrome ,Dietary Fats ,Mice, Inbred C57BL ,Disease Models, Animal ,Adipose Tissue ,Receptors, LDL ,Immunology ,medicine.symptom ,business ,Cardiology and Cardiovascular Medicine - Abstract
Background Obesity and particularly the metabolic syndrome, which is often associated with obesity, combine a major risk for type 2 diabetes and cardiovascular disease. Emerging evidence indicate obesity-associated subclinical inflammation primarily originating from adipose tissue as a common cause for type 2 diabetes and cardiovascular disease. However, a suitable and well-characterized mouse model to simultaneously study obesity-associated metabolic disorders and atherosclerosis is not available yet. Here we established and characterized a murine model combining diet-induced obesity and associated adipose tissue inflammation and metabolic deteriorations as well as atherosclerosis, hence reflecting the human situation of cardio-metabolic disease. Methods We compared a common high-fat diet with 0.15% cholesterol (HFC), and a high-fat, high-sucrose diet with 0.15% cholesterol (HFSC) fed to LDL receptor-deficient (LDLR-/-) mice. Insulin resistance, glucose tolerance, atherosclerotic lesion formation, hepatic lipid accumulation, and inflammatory gene expression in adipose tissue and liver were assessed. Results After 12–16 weeks, LDLR-/- mice fed HFSC or HFC developed significant diet-induced obesity, adipose tissue inflammation, insulin resistance, and impaired glucose tolerance compared to lean controls. Notably, HFSC-fed mice developed significantly higher adipose tissue inflammation in parallel with significantly elevated atherosclerotic lesion area compared to those on HFC. Moreover, LDLR-/- mice on HFSC showed increased insulin resistance and impaired glucose tolerance relative to those on HFC. After prolonged feeding (20 weeks), however, no significant differences in inflammatory and metabolic parameters as well as atherosclerotic lesion formation were detectable any more between LDLR-/- mice fed HFSC or HFC. Conclusion The use of high sucrose rather than more complex carbohydrates in high-fat diets significantly accelerates development of obesity-driven metabolic complications and atherosclerotic plaque formation parallel to obesity-induced adipose tissue inflammation in LDLR-/- mice. Hence LDLR-/- mice fed high-fat high-sucrose cholesterol-enriched diet appear to be a suitable and time-saving animal model for cardio-metabolic disease. Moreover our results support the suggested interrelation between adipose tissue inflammation and atherosclerotic plaque formation.
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