The Response of Murine Macrophages to Infection with Yersinia pestis as Revealed by DNA Microarray Analysis

Abstract

Macrophages play a crucial role in recognition and phagocytosis of pathogens and in the induction of response, immunity and immunopathology. A key strategy employed by numerous pathogens such as Yersinia pestis is to circumvent the immune response of the host via actively down-regulating the activation of macrophages. The study on host-pathogen interaction and gene expression is imperative for the development of alternative therapeutics. We have combined Suppression Subtractive Hybridisation (SSH), Microarray techniques, Northern blot analysis and quantitative reverse transcription coupled PCR (RT-PCR) to gain a view of differential host gene expression in response to Y. pestis-26 degrees C infection. In our study, a total of 22 different genes were identified as up-regulated in response to the Y. pestis infection. These genes include unknown EST's, cytokines, enzyme of cytokine, receptors, ligands, transcriptional factors, inhibitor of transcriptional factor, and proteins involved with cytoskeleton. More interestingly, among them are 7 genes that encode for factors known to be associated with cell cycling and cell proliferation, with 3 of them playing a role in apoptosis. Our data also indicate that macrophage cells undergo apoptosis during an infection with Y. pestis-37 degrees C, however an infection with 26 degrees C cultures results in a delayed apoptosis. The correlation between the delayed apoptosis and the up-regulation of anti-apoptotic gene is currently being studied.

The many and varied niches occupied by Yersinia pestis as an arthropod-vectored zoonotic pathogen

“…Future studies are likely to determine the transcription profile of Y. pestis cells residing intracellularly. The global response of the macrophage to infection by Y. pestis has been reported in a preliminary study where several genes were found to be up-regulated following infection by virulent Y. pestis (Ng et al 2003). Interestingly, a number of the up-regulated genes were involved in cell proliferation and antiapoptosis responses, suggesting that Y. pestis may actively prevent apoptosis in order to provide a niche for multiplication and trafficking to the local draining lymph node.…”

“…A number of studies have demonstrated the ability of Y. pestis to survive and multiply within macrophages, both in vitro and in vivo (Cavanaugh and Randall 1959;Finegold 1969;Straley and Harmon 1984a;Chartnetzky and Schuford 1985;Ng et al 2003;Pujol and Bliska 2003).The bacteria reside within the phagolysosomes of peritoneal macrophages and high bacterial loads are reached before the macrophages are killed and the bacteria are released (Straley and Harmon 1984b). Many virulence factors of Y. pestis have been tested for their ability to promote resistance to macrophage killing: pesticin, Pla, the pigmentation phenotype and the pCD1-encoded type three secretion system have been shown not to be required for bacterial survival (Straley and Harmon 1984b;Chartnetzky and Schuford 1985).…”

Human Cytolytic T Cell Recognition ofYersinia pestisVirulence Proteins That Target Innate Immune Responses

“…A cell contact-dependent type III secretion system (TTSS) injects Yersinia outer proteins (Yops) and additional virulence factors into the cytosol, which impairs several biochemical pathways associated with innate immunity. Translocation of the TTSS-associated factors into host cells results in profound changes in cytoskeletal dynamics, signal transduction, and cell-cell communication and ultimately progresses to apoptotic cell death [6,7]. Phagocytic cell death may allow bacteria to proliferate extracellularly [8] and to establish sequelae linked to morbidity and lethality.…”

Identification of host factors required for Yersinia pestis macrophage intracellular survival and their impact on vacuole maturation, acidification and trafficking.

“…Since these observations, multiple attempts have been made to identify both the bacterial ligand and eukaryotic receptor used by Y. pestis for invasion [31,49,[268][269][270][271]. Initially, Ng et al…”

“…conducted a microarray analysis of upregulated host genes during Y. pestis infection at 26°C in murine macrophages and identified Clec9a receptor [269]. However, Ng and colleagues were not specifically looking for receptors and neither this group nor others have followed up with this receptor.…”