Date on Master's Thesis/Doctoral Dissertation

5-2014

Document Type

Senior Honors Thesis

Department

Biology

Author's Keywords

Environmental mycobacteria; Innate immune system; Neutrophils; Glycolipids; Tuberculosis

Abstract

Mycobacteria smegmatis is an abundant soil and water inhabitant with which humans are continuously in contact. Despite the fact that it is typically considered non-­‐pathogenic, a few rare cases of M. smegmatis-­‐caused infections have been reported and it has been shown that M. smegmatis is able to modulate inflammatory responses in macrophages. Neutrophils are the innate immune system’s first line of centralized defense against invading microbes, especially the frequently encountered M. smegmatis. However, very little information is known of the mechanism by which neutrophils eliminate environmental bacteria. In this study, the hypothesis that M. smegmatis regulates neutrophil functional responses, and that some of these manipulations may involve M. smegmatis’ virulence-­‐associated glycolipid, PILAM was tested by specifically examining its effect on two of the major neutrophil responses: cytokine release and bacterial killing through degranulation and respiratory burst activity. Our data showed that this bacterium promotes inflammation, tissue damage and manipulates the Th1 response by controlling IL-­‐12. In addition, PILAM seems to be involved in the neutrophil responses of intracellular ROS, gelatinase granule exocytosis and IL-­‐12 release. Consequently, the interaction between human neutrophils and M. smegmatis appears to be much more intricate than formerly described.

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