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Fuchs CD, Dixon ED, Hendrikx T, Mlitz V, Wahlström A, Ståhlman M, Scharnagl H, Stojakovic T, Binder CJ, Marschall H, Trauner M. Tetrahydroxylated bile acids improve cholestatic liver and bile duct injury in the Mdr2 -/- mouse model of sclerosing cholangitis via immunomodulatory effects. Hepatol Commun 2022; 6:2368-2378. [PMID: 35691019 PMCID: PMC9426398 DOI: 10.1002/hep4.1998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/05/2022] [Accepted: 04/28/2022] [Indexed: 01/03/2023] Open
Abstract
Bile salt export pump (Bsep) (Abcb11)-/- mice are protected from acquired cholestatic injury due to metabolic preconditioning with a hydrophilic bile acid (BA) pool with formation of tetrahydroxylated bile acids (THBAs). We aimed to explore whether loss of Bsep and subsequent elevation of THBA levels may have immunomodulatory effects, thus improving liver injury in the multidrug resistance protein 2 (Mdr2) (Abcb4)-/- mouse. Cholestatic liver injury in Mdr2-/- Bsep-/- double knockout (DKO), Mdr2-/- , Bsep-/- , and wild-type mice was studied for comparison. Mdr2-/- mice were treated with a THBA (3α,6α,7α,12α-Tetrahydroxycholanoic acid). RNA/protein expression of inflammatory/fibrotic markers were investigated. Serum BA-profiling was assessed by ultra-performance liquid chromatography tandem mass spectrometry. Hepatic immune cell profile was quantified by flow cytometric analysis (FACS). In vitro, the THBA effect on chenodeoxycholic acid (CDCA)-induced inflammatory signaling in hepatocyte and cholangiocytes as well as lipopolysaccharide (LPS)/interferon-γ (IFN-γ)-induced macrophage activation was analyzed. In contrast to Mdr2-/- , DKO mice showed no features of sclerosing cholangitis. Sixty-seven percent of serum BAs in DKO mice were polyhydroxylated (mostly THBAs), whereas Mdr2-/- mice did not have these BAs. Compared with Mdr2-/- , DKO animals were protected from hepatic inflammation/fibrosis. THBA feeding in Mdr2-/- mice improved liver injury. FACS analysis in DKO and Mdr2-/- THBA-fed mice showed changes of the hepatic immune cell profile towards an anti-inflammatory pattern. Early growth response 1 (EGR1) protein expression was reduced in DKO and in Mdr2-/- THBA-fed mice compared with Mdr2-/- control mice. In vitro, THBA-reduced CDCA induced EGR1 protein and mRNA expression of inflammatory markers in hepatocytes and cholangiocytes. LPS/IFN-γ-induced macrophage activation was ameliorated by THBA. THBAs repress EGR1-related key pro-inflammatory pathways. Conclusion: THBA and their downstream targets may represent a potential treatment strategy for cholestatic liver diseases.
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Affiliation(s)
- Claudia D. Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - Emmanuel D. Dixon
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - Tim Hendrikx
- Department of Laboratory MedicineMedical University of ViennaViennaAustria
- Department of Molecular GeneticsMaastricht UniversityMaastrichtthe Netherlands
| | - Veronika Mlitz
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - Annika Wahlström
- Department of Molecular and Clinical MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Marcus Ståhlman
- Department of Molecular and Clinical MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory DiagnosticsMedical University of GrazGrazAustria
| | - Tatjana Stojakovic
- Clinical Institute of Medical and Chemical Laboratory DiagnosticsUniversity Hospital GrazGrazAustria
| | | | - Hanns‐Ulrich Marschall
- Department of Molecular and Clinical MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine IIIMedical University of ViennaViennaAustria
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2
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Fuchs CD, Radun R, Dixon ED, Mlitz V, Timelthaler G, Halilbasic E, Herac M, Jonker JW, Ronda OAHO, Tardelli M, Haemmerle G, Zimmermann R, Scharnagl H, Stojakovic T, Verkade HJ, Trauner M. Hepatocyte-specific deletion of adipose triglyceride lipase (adipose triglyceride lipase/patatin-like phospholipase domain containing 2) ameliorates dietary induced steatohepatitis in mice. Hepatology 2022; 75:125-139. [PMID: 34387896 DOI: 10.1002/hep.32112] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/29/2021] [Accepted: 08/11/2021] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIMS Increased fatty acid (FA) flux from adipose tissue to the liver contributes to the development of NAFLD. Because free FAs are key lipotoxic triggers accelerating disease progression, inhibiting adipose triglyceride lipase (ATGL)/patatin-like phospholipase domain containing 2 (PNPLA2), the main enzyme driving lipolysis, may attenuate steatohepatitis. APPROACH AND RESULTS Hepatocyte-specific ATGL knockout (ATGL LKO) mice were challenged with methionine-choline-deficient (MCD) or high-fat high-carbohydrate (HFHC) diet. Serum biochemistry, hepatic lipid content and liver histology were assessed. Mechanistically, hepatic gene and protein expression of lipid metabolism, inflammation, fibrosis, apoptosis, and endoplasmic reticulum (ER) stress markers were investigated. DNA binding activity for peroxisome proliferator-activated receptor (PPAR) α and PPARδ was measured. After short hairpin RNA-mediated ATGL knockdown, HepG2 cells were treated with lipopolysaccharide (LPS) or oleic acid:palmitic acid 2:1 (OP21) to explore the direct role of ATGL in inflammation in vitro. On MCD and HFHC challenge, ATGL LKO mice showed reduced PPARα and increased PPARδ DNA binding activity when compared with challenged wild-type (WT) mice. Despite histologically and biochemically pronounced hepatic steatosis, dietary-challenged ATGL LKO mice showed lower hepatic inflammation, reflected by the reduced number of Galectin3/MAC-2 and myeloperoxidase-positive cells and low mRNA expression levels of inflammatory markers (such as IL-1β and F4/80) when compared with WT mice. In line with this, protein levels of the ER stress markers protein kinase R-like endoplasmic reticulum kinase and inositol-requiring enzyme 1α were reduced in ATGL LKO mice fed with MCD diet. Accordingly, pretreatment of LPS-treated HepG2 cells with the PPARδ agonist GW0742 suppressed mRNA expression of inflammatory markers. Additionally, ATGL knockdown in HepG2 cells attenuated LPS/OP21-induced expression of proinflammatory cytokines and chemokines such as chemokine (C-X-C motif) ligand 5, chemokine (C-C motif) ligand (Ccl) 2, and Ccl5. CONCLUSIONS Low hepatic lipolysis and increased PPARδ activity in ATGL/PNPLA2 deficiency may counteract hepatic inflammation and ER stress despite increased steatosis. Therefore, lowering hepatocyte lipolysis through ATGL inhibition represents a promising therapeutic strategy for the treatment of steatohepatitis.
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Affiliation(s)
- Claudia D Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Richard Radun
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Emmanuel D Dixon
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Veronika Mlitz
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Gerald Timelthaler
- Institute for Cancer Research, Internal Medicine I, Medical University of Vienna, Vienna, Austria
| | - Emina Halilbasic
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Merima Herac
- Clinical Institute of Pathology, Medical University Vienna, Vienna, Austria
| | - Johan W Jonker
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Onne A H O Ronda
- Pediatric Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Matteo Tardelli
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.,Division of Gastroenterology and Hepatology, Department of Medicine, Weill Cornell Medical College, New York, New York, USA
| | - Guenter Haemmerle
- BioTechMed-Graz, Graz, Austria.,Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Robert Zimmermann
- BioTechMed-Graz, Graz, Austria.,Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Tatjana Stojakovic
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Graz, Graz, Austria
| | - Henkjan J Verkade
- Pediatric Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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Dixon ED, Nardo AD, Claudel T, Trauner M. The Role of Lipid Sensing Nuclear Receptors (PPARs and LXR) and Metabolic Lipases in Obesity, Diabetes and NAFLD. Genes (Basel) 2021; 12:genes12050645. [PMID: 33926085 PMCID: PMC8145571 DOI: 10.3390/genes12050645] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 12/11/2022] Open
Abstract
Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.
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Affiliation(s)
| | | | | | - Michael Trauner
- Correspondence: ; Tel.: +43-140-4004-7410; Fax: +43-14-0400-4735
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Zwirzitz B, Wetzels SU, Dixon ED, Fleischmann S, Selberherr E, Thalguter S, Quijada NM, Dzieciol M, Wagner M, Stessl B. Co-Occurrence of Listeria spp. and Spoilage Associated Microbiota During Meat Processing Due to Cross-Contamination Events. Front Microbiol 2021; 12:632935. [PMID: 33613505 PMCID: PMC7892895 DOI: 10.3389/fmicb.2021.632935] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/13/2021] [Indexed: 12/27/2022] Open
Abstract
A large part of foodborne outbreaks related to Listeria monocytogenes are linked to meat and meat products. Especially, recontamination of meat products and deli-meat during slicing, packaging, and repackaging is in the focus of food authorities. In that regard, L. monocytogenes persistence in multi-species biofilms is one major issue, since they survive elaborate cleaning and disinfection measures. Here, we analyzed the microbial community structure throughout a meat processing facility using a combination of high-throughput full-length 16S ribosomal RNA (rRNA) gene sequencing and traditional microbiological methods. Samples were taken at different stages during meat cutting as well as from multiple sites throughout the facility environment to capture the product and the environmental associated microbiota co-occurring with Listeria spp. and L. monocytogenes. The listeria testing revealed a widely disseminated contamination (50%; 88 of 176 samples were positive for Listeria spp. and 13.6%; 24 of 176 samples were positive for L. monocytogenes). The pulsed-field gel electrophoresis (PFGE) typing evidenced 14 heterogeneous L. monocytogenes profiles with PCR-serogroup 1/2a, 3a as most dominant. PFGE type MA3-17 contributed to the resilient microbiota of the facility environment and was related to environmental persistence. The core in-house microbiota consisted mainly of the genera Acinetobacter, Pseudomonas, Psychrobacter (Proteobacteria), Anaerobacillus, Bacillus (Firmicutes), and Chryseobacterium (Bacteroidota). While the overall microbial community structure clearly differed between product and environmental samples, we were able to discern correlation patterns regarding the presence/absence of Listeria spp. in both sample groups. Specifically, our longitudinal analysis revealed association of Listeria spp. with known biofilm-producing Pseudomonas, Acinetobacter, and Janthinobacterium species on the meat samples. Similar patterns were also observed on the surface, indicating dispersal of microorganisms from this multispecies biofilm. Our data provided a better understanding of the built environment microbiome in the meat processing context and promoted more effective options for targeted disinfection in the analyzed facility.
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Affiliation(s)
- Benjamin Zwirzitz
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.,Austrian Competence Center for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Stefanie U Wetzels
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.,Austrian Competence Center for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Emmanuel D Dixon
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Svenja Fleischmann
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Evelyne Selberherr
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Sarah Thalguter
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Narciso M Quijada
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.,Austrian Competence Center for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Monika Dzieciol
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Martin Wagner
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.,Austrian Competence Center for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Beatrix Stessl
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
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5
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Nardo AD, Schneeweiss‐Gleixner M, Bakail M, Dixon ED, Lax SF, Trauner M. Pathophysiological mechanisms of liver injury in COVID-19. Liver Int 2021; 41:20-32. [PMID: 33190346 PMCID: PMC7753756 DOI: 10.1111/liv.14730] [Citation(s) in RCA: 203] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/05/2020] [Accepted: 11/06/2020] [Indexed: 02/06/2023]
Abstract
The recent outbreak of coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has resulted in a world-wide pandemic. Disseminated lung injury with the development of acute respiratory distress syndrome (ARDS) is the main cause of mortality in COVID-19. Although liver failure does not seem to occur in the absence of pre-existing liver disease, hepatic involvement in COVID-19 may correlate with overall disease severity and serve as a prognostic factor for the development of ARDS. The spectrum of liver injury in COVID-19 may range from direct infection by SARS-CoV-2, indirect involvement by systemic inflammation, hypoxic changes, iatrogenic causes such as drugs and ventilation to exacerbation of underlying liver disease. This concise review discusses the potential pathophysiological mechanisms for SARS-CoV-2 hepatic tropism as well as acute and possibly long-term liver injury in COVID-19.
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Affiliation(s)
- Alexander D. Nardo
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyDepartment of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - Mathias Schneeweiss‐Gleixner
- Medical Intensive Care Unit 13H1. Division of Gastroenterology and HepatologyDepartment of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - May Bakail
- Campus ITInstitute of Science and Technology AustriaKlosterneuburgAustria
| | - Emmanuel D. Dixon
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyDepartment of Internal Medicine IIIMedical University of ViennaViennaAustria
| | - Sigurd F. Lax
- Department of PathologyHospital Graz IIAcademic Teaching Hospital of the Medical University of GrazGrazAustria,School of MedicineJohannes Kepler UniversityLinzAustria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyDepartment of Internal Medicine IIIMedical University of ViennaViennaAustria,Medical Intensive Care Unit 13H1. Division of Gastroenterology and HepatologyDepartment of Internal Medicine IIIMedical University of ViennaViennaAustria
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6
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Nardo AD, Schneeweiss-Gleixner M, Bakail M, Dixon ED, Lax SF, Trauner M. Pathophysiological mechanisms of liver injury in COVID-19. Liver Int 2020. [PMID: 33190346 DOI: 10.1111/liv.14730.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The recent outbreak of coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has resulted in a world-wide pandemic. Disseminated lung injury with the development of acute respiratory distress syndrome (ARDS) is the main cause of mortality in COVID-19. Although liver failure does not seem to occur in the absence of pre-existing liver disease, hepatic involvement in COVID-19 may correlate with overall disease severity and serve as a prognostic factor for the development of ARDS. The spectrum of liver injury in COVID-19 may range from direct infection by SARS-CoV-2, indirect involvement by systemic inflammation, hypoxic changes, iatrogenic causes such as drugs and ventilation to exacerbation of underlying liver disease. This concise review discusses the potential pathophysiological mechanisms for SARS-CoV-2 hepatic tropism as well as acute and possibly long-term liver injury in COVID-19.
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Affiliation(s)
- Alexander D Nardo
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Mathias Schneeweiss-Gleixner
- Medical Intensive Care Unit 13H1. Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - May Bakail
- Campus IT, Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Emmanuel D Dixon
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Sigurd F Lax
- Department of Pathology, Hospital Graz II, Academic Teaching Hospital of the Medical University of Graz, Graz, Austria.,School of Medicine, Johannes Kepler University, Linz, Austria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.,Medical Intensive Care Unit 13H1. Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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Susskind BM, Schall R, Dixon ED. Regulatory mechanisms in cytotoxic T lymphocyte development. II. Dissociation of in vitro cytotoxic T-lymphocyte and suppressor T-cell activities with L-ornithine. Cell Immunol 1986; 101:512-23. [PMID: 2944613 DOI: 10.1016/0008-8749(86)90162-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
L-ornithine was found to differentially affect the induction of allospecific cytotoxic T lymphocytes (CTL) and suppressor T cells (Ts). At a concentration of 10 mM, ornithine inhibited the development of CTL in a mixed-leukocyte culture (MLC). This same population of cells suppressed the generation of CTL when irradiated and cocultured with fresh syngeneic lymphocytes and alloantigen. Suppression was mediated by Lyt-1-2+ cells and was antigen specific. Suppression was abrogated when IL-2 (10 U/ml) was added to the cocultures, but could not be reversed by increasing the antigen dose. Ornithine was not toxic to CTL precursors but rather arrested their development. Cells from MLC plus ornithine developed CTL activity within 2 days of transfer to secondary cultures in the absence of ornithine. Development of CTL effector cells (CTLe) was augmented by but did not require exogenous IL-2. Generation of CTLe from the MLC plus ornithine population was radiation sensitive and could be inhibited by reexposure to ornithine, even in the presence of IL-2. Thus, Lyt-1-2+ T cells allostimulated in vitro in MLC plus ornithine and lacking CTL activity convey radiation-resistant, antigen-specific suppression.
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MESH Headings
- Animals
- Cells, Cultured
- Gamma Rays
- Isoantigens/immunology
- Lymphocyte Culture Test, Mixed
- Mice
- Mice, Inbred C3H/immunology
- Mice, Inbred C57BL/immunology
- Mice, Inbred DBA/immunology
- Ornithine/pharmacology
- T-Lymphocytes, Cytotoxic/drug effects
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/radiation effects
- T-Lymphocytes, Regulatory/drug effects
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/radiation effects
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