A microarray analysis of the murine macrophage response to infection with Francisella tularensis LVS.
The response of cells of the mouse macrophage cell line J774 to infection with Francisella tularensis LVS was analysed by means of a DNA microarray representing approximately 18,500 genes (20,600 clones). The adaptive response was modest at all time points, and at most, 81 clones were differentially regulated from the time point of uptake of bacteria (0 min) up to 240 min later. For all five time points, 229 clones fulfilled the criteria of being differentially regulated, i.e. the ratio between infected versus non-infected cells was at least 1.7-fold up- or down-regulated and P <0.05. It was found that many of the differentially regulated genes are known to respond to stress in general and to oxidative stress specifically. However, at 120 min it was observed that genes that lead to depletion of glutathione were upregulated. Possibly, this was a result of mechanisms induced by F. tularensis. Generally, there was a conspicuous lack of inflammatory responses and, for example, although tumour necrosis factor alpha (TNF-alpha) was upregulated at 0 min, a significant down-regulation was noted at all subsequent time points. When cells were treated with an inhibitor of inducible nitric oxide synthase (iNOS) or the antioxidant N-acetylcysteine (NAC), the infection-induced cytopathogenic effect was significantly inhibited. Together, the results suggest that F. tularensis LVS infection confers an oxidative stress upon the target cells and that many of the host-defence mechanisms appear to be intended to counteract this stress. The infection is characterized by a very modest inflammatory response.
Andersson
Henrik
H
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
Hartmanová
Blanka
B
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
Rydén
Patrik
P
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
Noppa
Laila
L
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
Näslund
Linda
L
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
Sjöstedt
Anders
A
Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, SE-901 85 Umeå, Sweden.
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D002999:Clone Cells / Q000378:metabolism; D005604:Francisella tularensis / Q000254:growth & development; D016166:Free Radical Scavengers / Q000494:pharmacology; D020869:Gene Expression Profiling; D005978:Glutathione / Q000235:genetics / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D013997:Time Factors; D014406:Tularemia / Q000382:microbiology* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D016166:Free Radical Scavengers; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II; D005978:Glutathione; D000111:Acetylcysteine