Honors Theses


Yvonne Sun, Ph.D.



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Honors Thesis


Macrophages are one of the many essential cells of the innate immune system that help to protect the body from dangerous pathogens such as Listeria monocytogenes. L. monocytogenes is a foodborne pathogen that can cause infections, especially in the elderly, immunocompromised, and pregnant women. The antimicrobial activities of macrophages that are utilized to respond to pathogens such as L. monocytogenes can include phagocytosis, inflammatory responses, and the production of antimicrobial compounds such as nitric oxide. These activities need to be regulated carefully to avoid causing unintentional damages. Typically, macrophages exist in a naive, unactivated state, or can be activated classically (M1) and alternatively (M2) by different cytokines. Furthermore, propionate, a major gut metabolite, can also influence macrophage activities. To better understand how propionate affects macrophage antimicrobial activities, I investigated how the morphology and motility of macrophages at various activation states are altered by propionate treatment. Using cell culture-based assays, I observed that propionate elongates nonactivated, M1, and M2 activated macrophages, indicating that propionate may modulate a macrophages response to infection. Additional experiments were performed to assess how propionate treatment of the activated macrophage impacts infection with L. monocytogenes, glucose consumption, and cell motility. The findings from this research will help to identify ways in which propionate can enhance macrophage ability to respond and fight dangerous pathogens such as L. monocytogenes.

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Undergraduate research