Implication of CpG-ODN and reactive oxygen species in the inhibition of intracellular growth of Salmonella typhimurium in hepatocytes.
Bacterial DNA acts as an alert signal for eukaryotic cells through immunostimulatory CpG motifs. These sequences have therapeutic properties promoting protective immune TH1 responses and are recognized by a membrane protein belonging to the Toll-like receptor (TLR) family, named TLR-9. The aim of this study was to test the capability of murine hepatocytes to sense bacterial DNA and to develop antibacterial mechanisms against Salmonella typhimurium. We show that hepatocyte cell lines and mRNA extracts from murine liver constitutively express TLR-9, which is down-regulated by LPS and the mix of IFNgamma, IL-1beta and LPS. Also, we have found that hepatocyte cell lines can sense the presence of bacterial DNA and respond to it by increasing the pool of intracellular peroxides. This results in inhibition of intracellular growth of S. typhimurium when infected cells were incubated in the presence of CpG synthetic oligonucleotides (CpG-ODN). Expression of hepatocyte Mn-SOD is also induced by stimulation with CpG-oligodeoxynucleotides, LPS, and the mix of IFNgamma, IL-1beta and LPS. These results reinforce the prominent role of hepatocytes as a microbial product-responsive cell and the capabilities of CpG-ODN sequences as potent inducers of the innate immune response through the activation of a broad range of cell types.
Sanchez-Campillo
María
M
Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, 30100 Murcia, Spain.
Chicano
Antonio
A
Torío
Alberto
A
Martín-Orozco
Elena
E
Gámiz
Pilar
P
Hernández-Caselles
Trinidad
T
García-Peñarrubia
Pilar
P
D000818:Animals; D002460:Cell Line; D018899:CpG Islands; D016207:Cytokines; D005260:Female; D022781:Hepatocytes / Q000382:microbiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010545:Peroxides / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development*; D013482:Superoxide Dismutase / Q000378:metabolism; D051193:Toll-Like Receptors
C408982:CPG-oligonucleotide; D016207:Cytokines; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D010545:Peroxides; D017382:Reactive Oxygen Species; D011956:Receptors, Cell Surface; D051193:Toll-Like Receptors; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D013482:Superoxide Dismutase