Microarray analysis of response of Salmonella during infection of HLA-B27- transfected human macrophage-like U937 cells.
BACKGROUND
Human leukocyte antigen (HLA)-B27 is strongly associated with the development of reactive arthritis (ReA) in humans after salmonellosis. Human monocytic U937 cells transfected with HLA-B27 are less able to eliminate intracellular Salmonella enterica serovar Enteritidis than those transfected with control HLA antigens (e.g. HLA-A2). To investigate further the mechanisms by which HLA-B27-transfected cells allow increased replication of these bacteria, a DNA-based microarray was used for comparative genomic analysis of S. Enteritidis grown in HLA-B27- or HLA-A2-transfected cells. The microarray consisted of 5080 oligonucleotides from different serovars of Salmonella including S. Enteritidis PT4-specific genes. Bacterial RNA was isolated from the infected HLA-B27- or HLA-A2-transfected cells, reverse-transcribed to cDNA, and hybridized with the oligonucleotides on the microarrays. Some microarray results were confirmed by RT-PCR.


RESULTS
When gene expression was compared between Salmonella grown in HLA-B27 cells and in HLA-A2 cells, 118 of the 4610 S. Enteritidis-related genes differed in expression at 8 h after infection, but no significant difference was detectable at 2 h after infection. These differentially expressed genes are mainly involved in Salmonella virulence, DNA replication, energy conversion and metabolism, and uptake and metabolism of nutrient substances, etc. The difference suggests HLA-B27-dependent modulation of Salmonella gene expression, resulting in increased Salmonella replication in HLA-B27-positive cells. Among the up-regulated genes were those located in Salmonella pathogenicity island (SPI)-2, which play a central role in intracellular survival and replication of Salmonella.


CONCLUSIONS
This is the first report to show the regulation of Salmonella gene expression by HLA-B27 during infection of host cells. This regulation probably leads to increased Salmonella survival and replication in HLA-B27-positive cells. SPI-2 genes seem to contribute significantly to the increased replication.
Ge
Shichao
S
Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Turku, Finland.
Danino
Vittoria
V
He
Qiushui
Q
Hinton
Jay C D
JC
Granfors
Kaisa
K
D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015796:HLA-B27 Antigen / Q000276:immunology*; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D000091402:Prohibitins; D017382:Reactive Oxygen Species / Q000378:metabolism; D012475:Salmonella / Q000235:genetics* / Q000502:physiology; D020298:U937 Cells
D004269:DNA, Bacterial; D015796:HLA-B27 Antigen; C000717331:PHB2 protein, human; D000091402:Prohibitins; D017382:Reactive Oxygen Species