Gene expression profiling of human promyelocytic cells in response to infection with Anaplasma phagocytophilum

Abstract

SummaryAnaplasma phagocytophilum (Rickettsiales: Anaplasmataceae) causes human, equine and canine granulocytic anaplasmosis and tick-borne fever of ruminants. The rickettsia parasitizes granulocytes and bone marrow progenitor cells, and can be propagated in human promyelocytic and tick cell lines. In this study, microarrays of synthetic polynucleotides of 21 329 human genes were used to identify genes that are differentially expressed in HL-60 human promyelocytic cells in response to infection with A. phagocytophilum . Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) of selected genes confirmed the results of the microarray analysis. Six genes in the A. phagocytophiluminfected cells were found to be upregulated greater than 30-fold, while expression of downregulated genes most often did not change more than sixfold. Genes that were found to be differentially regulated in infected cells were those essential for cellular mechanisms including growth and differentiation, cell transport, signalling and communication and protective response against infection, some of which are most likely necessary for infection and multiplication of A. phagocytophilum in host cells. The differentially regulated genes described herein provide new information on the gene expression profiles in A. phagocytophilum -infected HL-60 cells, thus expanding in a global manner the existing information on the response of mammalian cells to A. phagocytophilum infection.

Early Transcriptional Response of Human Neutrophils toAnaplasma phagocytophilumInfection

“…Another noteworthy study on the host response to A. phagocytophilum infection was by de la Fuente et al, who analyzed the expression profile of HL-60 cells at 3 days postinfection by using a synthetic polynucleotide microarray comprising 21,329 human genes (21). Out of approximately 200 genes whose expression was altered at least twofold during A. phagocytophilum infection of undifferentiated HL-60 cells, none were in common with our results.…”

“…Borjesson and colleagues have also studied the global changes in neutrophil transcription following A. phagocytophilum infection (8). We and de la Fuente et al have also performed similar studies using the HL-60 and NB4 promyelocytic cell lines (12,21,60). The availability of data from these four global expression analyses presents an excellent opportunity for delineating common transcriptional profiles, if any, induced by A. phagocytophilum among different host cell types.…”

“…In the case of A. phagocytophilum, we have previously shown by use of macroarray analysis that the bacterium causes repression of rac2 mRNA expression in human promyelocytic HL-60 cells, with a resulting influence on the host cell capacity to generate a respiratory burst (12). Recent microarray studies by our group and others have analyzed the global gene expression responses of HL-60 cells (21), NB4 cells (60), and human neutrophils (8) to A. phagocytophilum infection.…”

“…The availability of data from four previous studies that examined the transcriptional response of human neutrophils (8), HL-60 cells (12,21), and NB4 cells (60) to A. phagocytophilum infection at various time points offers an excellent opportunity Table S1 in the supplementary material). The GO classification was based on the GO slim format (http://www.geneontology.org/GO.slims.shtml) (see Table 2).…”

Experimental Infection of C3H/HeJ Mice with the NY18 Isolate of Anaplasma phagocytophilum

“…The sequence of the msp4 DNA amplified from infected mice was the same as the PCR sequence derived from the NY18 isolate infection in cultured HL-60 cells (Genbank accession number AY530194). 17 All HL-60 cell cultures inoculated with blood from infected mice became infected with A phagocytophilum. Cultures inoculated with blood from day 7 were positive for morulae after 4 days in culture and reached 100% infection by day 8.…”