Multiple redundant stress resistance mechanisms are induced in Salmonella enterica serovar Typhimurium in response to alteration of the intracellular environment via TLR4 signalling.
Toll-like receptor 4 (TLR4) senses bacterial LPS and is required for the control of systemic Salmonella enterica serovar Typhimurium infection in mice. The mechanisms of TLR4 activation and its downstream signalling cascades are well described, yet the direct effects on the pathogen of signalling via this receptor remain unknown. To investigate this we used microarray-based transcriptome profiling of intracellular S. Typhimurium during infection of primary bone marrow-derived macrophages from wild-type and TLR4-deficient mice. We identified 17 S. Typhimurium genes that were upregulated in the presence of functional TLR4. Nine of these genes have putative functions in oxidative stress resistance. We therefore examined S. Typhimurium gene expression during infection of NADPH oxidase-deficient macrophages, which lack normal oxidative killing mechanisms. We identified significant overlap between the 'TLR4-responsive' and 'NADPH oxidase-responsive' genes. This is new evidence for a link between TLR4 signalling and NADPH oxidase activity. Interestingly, with the exception of a dps mutant, S. Typhimurium strains lacking individual TLR4- and/or oxidative stress-responsive genes were not attenuated during intravenous murine infections. Our study shows that TLR4 activity, either directly or indirectly, induces the expression of multiple stress resistance genes during the intracellular life of S. Typhimurium.
Wright
John A
JA
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Tötemeyer
Sabine S
SS
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Hautefort
Isabelle
I
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Appia-Ayme
Corinne
C
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Alston
Mark
M
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Danino
Vittoria
V
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Paterson
Gavin K
GK
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Mastroeni
Pietro
P
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Ménager
Nathalie
N
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Rolfe
Matthew
M
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Thompson
Arthur
A
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Ugrinovic
Sanja
S
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Sait
Leanne
L
School of Clinical Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, UK.
Humphrey
Tom
T
School of Clinical Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, UK.
Northen
Helen
H
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Peters
Sarah E
SE
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Maskell
Duncan J
DJ
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Hinton
Jay C D
JCD
Molecular Microbiology Group, Institute of Food Research, Norwich NR4 7UA, UK.
Bryant
Clare E
CE
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
D000818:Animals; D018929:Cell Culture Techniques; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D054884:Host-Pathogen Interactions; D051379:Mice; D018384:Oxidative Stress / Q000235:genetics; D012329:RNA, Bacterial / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D011971:Receptors, Immunologic / Q000378:metabolism; D012481:Salmonella Infections, Animal / Q000378:metabolism* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000472:pathogenicity / Q000502:physiology*; D015398:Signal Transduction; D013312:Stress, Physiological / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014774:Virulence
C105949:Pirb protein, mouse; D012329:RNA, Bacterial; D011971:Receptors, Immunologic; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4