Selective priming to Toll-like receptor 4 (TLR4), not TLR2, ligands by P. acnes involves up-regulation of MD-2 in mice
Authors
Romics, LaszloDolganiuc, Angela
Kodys, Karen
Drechsler, Yvonne
Oak, Shilpa
Velayudham, Arumugam
Mandrekar, Pranoti
Szabo, Gyongyi
UMass Chan Affiliations
Department of Medicine, Division of GastroenterologyDepartment of Medicine, Rheumatology Division
Document Type
Journal ArticlePublication Date
2004-09-07Keywords
AnimalsAntigens, CD14
Antigens, Ly
Cytokines
Female
Interferon-gamma
Lipopolysaccharides
Liver
Lymphocyte Antigen 96
Membrane Glycoproteins
Mice
Mice, Inbred C57BL
Propionibacterium acnes
Receptors, Cell Surface
Toll-Like Receptor 1
Toll-Like Receptor 2
Toll-Like Receptor 4
Toll-Like Receptors
Up-Regulation
Gastroenterology
Immunology and Infectious Disease
Rheumatology
Metadata
Show full item recordAbstract
Lipopolysaccharide (LPS) triggers cytokine production through Toll-like receptor 4 (TLR4), which shares downstream signaling pathways with TLR2. We investigated the roles of TLR2 and TLR4 in Propionibacterium acnes (P. acnes)-primed, LPS-induced liver damage using selective TLR ligands. Stock LPS induced interleukin 8 in both TLR4- and TLR2-expressing human embryonic kidney (HEK) 293 cells. Purified LPS (TLR4 ligand) activated HEK/TLR4 cells, while peptidoglycan and lipoteichoic acid (TLR2 ligands) activated HEK/TLR2 cells, respectively. In mice, P. acnes priming resulted in increased liver messenger RNA (mRNA) and serum levels of tumor necrosis factor alpha, interleukin 12, and interferon gamma (IFN-gamma) by both stock LPS and purified LPS challenges compared with nonprimed controls. In contrast, P. acnes failed to sensitize to TLR2 ligands (peptidoglycan + lipoteichoic acid). In the liver, P. acnes-priming was associated with up-regulation of TLR4 and MD-2 proteins, and subsequent LPS challenge further increased MD-2 and CD14 mRNA levels. The lack of sensitization to TLR2 ligands by P. acnes correlated with no increase in hepatic TLR1 or TLR6 mRNA. In vitro, P. acnes pretreatment desensitized RAW macrophages to a secondary stimulation via both TLR2 and TLR4. However, IFN-gamma could selectively prevent desensitization to TLR4 but not to TLR2 ligands. Furthermore, P. acnes induced production of IFN-gamma in vivo as well as in isolated splenocytes. In vitro, P. acnes-primed Hepa 1-6 hepatocytes but not RAW macrophages produced increased MD-2 and CD14 mRNA levels after an LPS challenge. In conclusion, P. acnes priming to selective TLR4-mediated liver injury is associated with up-regulation of TLR4 and MD-2 and is likely to involve IFN-gamma and prevent TLR4 desensitization by P. acnes.Source
Hepatology. 2004 Sep;40(3):555-64. Link to article on publisher's siteDOI
10.1002/hep.20350Permanent Link to this Item
http://hdl.handle.net/20.500.14038/31112PubMed ID
15349893Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1002/hep.20350
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