Bacterial pathogens modulate an apoptosis differentiation program in human neutrophils¹

Speaker: 姚蕙雯

Commentator: 何漣漪 老師

Time: 2003/12/03 pm 2:00-3:00

Abstract:

During bacterial infection, acute inflammatory response is triggered to eliminate the foreign invaders by recruitment of effector cells, especially polymorphonuclear leukocytes (PMNs).  The recruited PMNs can take up pathogens or their products by phagocytosis and also can sustain acute inflammatory response to act continually.  Although the inflammation is beneficial to the host, it may turn out to be harmful if it is not regulated appropriately.  Since the PMNs are the most abundant effector cells in acute inflammatory responses, regulation the life span of PMNs may be helpful to the resolution of inflammation.  Based on previous studies, some bacterial pathogens could alter innate immune responses of hosts by modulating the gene expression of PBMCs² and macrophages³.  However this phenomenon in neutrophils is still not very clearly.  In order to clarify these molecular events, the authors used microarray to analyze gene expression in neutrophils. They found that global changes at the transcriptional level increased with time after phagocytosis of bacterial pathogens, especially those genes encoding key effectors of apoptosis and receptors for immune responses.  These findings were confirmed by quantitative RT-PCR.  Not only at the transcriptional level, the surface expression of proteins on neutrophils, like IL-8 receptors, also changed with time.  Besides, they found that S. pyrogenes could induce a significantly different pattern in the rapid promotion of PMN apoptosis and the suppression of host immune response. Based on the results of this study, the authors suggested that phagocytosis of bacterial pathogens could modulate an apoptosis differentiation program in human neutrophils, which may result in the resolution of infection or the onset of disease due to pathogen survival.

References:

1.     Kobayashi, S. D., et al. 2003. Bacterial pathogens modulate an apoptosis differentiation program in human neutrophils. PNAS. 100: 10948-10953.

2.     Boldrick, J. C., et al. 2002. Stereotyped and specific gene expression programs in human innate immune response to bacterial. PNAS. 99: 972-977.

3.     Nau, G. J., et al. Human macrophage activation programs induced by bacterial pathogens. PNAS. 99: 1503-1508.