Date of Award
Master of Science (MS)
Microbiology and Immunology
The human body contains a diverse ecosystem of microbes. Commensal bacteria have numerous mutually-beneficial relationships with their host. Not only do they assist in digestion and gut homeostasis, they are critical for development and function of the immune system. As such, hosts and microbes alike have evolved mechanisms to foster symbiosis. Gut barrier function, toll-like receptor signaling, and metabolites are all examples of how hosts interact with microbes to promote this mutually-beneficial relationship. Metabolites from commensal bacteria promote the generation of regulatory T-cells, capable of ameliorating inflammation. A number of inflammatory, allergic, and autoimmune conditions are associated with dysbiosis. Therefore, probiotics have been suggested as a potential treatment. Probiotics have proven efficacious in reducing inflammation. Oral administration of probiotics generates regulatory T-cells. Similarly, probiotics can reduce induced colitis. While probiotics for the treatment of inflammation are promising, little is known about how they confer these positive effects. This thesis explored the effects and mechanism of a novel metabolite, NC, isolated from theTNF⍺ release in response to TLR3 and TLR4 agonists in human and murine macrophage-like cells. NC did not significantly reduce IL-6 production in response to TLR3 or TLR5 agonists in human corneal epithelial cells, nor did NC induce pro-inflammatory cytokine release in unstimulated cells. NC may act through TRIF, as TRIF is the only adaptor associated with TLR3. In order to determine if NC reduces TNF⍺ release through NFκB, cell lysates were taken from cells treated with NC following stimulation with TLR3 and TLR4 agonists and phospho-NFκB was quantified. NC reduced phospho-NFκB, which suggests NC reduces NFκB activation. NC was later evaluated for its ability to reduce inflammation in vivo. Mice were given intraperitoneal injections of NC for 2 days before being given an intraperitoneal injection of LPS to induce peritonitis, a model of endotoxemia. If NC is able to reduce the amount of neutrophils recruited to the peritoneal cavity following lipopolysaccharide (LPS) injection, then it is effective at reducing TLR-4 related inflammation in vivo. NC significantly reduced CD11b+ Ly6G high cells, or neutrophils, in mice given LPS-induced peritonitis when compared to controls. NC is effective in reducing inflammation in vitro and in vivo in response to TLR3 and TLR4 agonists. Due to its ability to mediate inflammatory markers in endotoxemia in vivo NC is a promising candidate to reduce the inflammation which can lead to organ failure and death in sepsis. Furthermore, through this novel small-molecule drug, we were able to explore one facet of how Lactobacillus probiotics interact with the immune system to reduce inflammation.
Landrowski, Drew Hahnnah, "Lactobacillus Metabolite NC as an Inflammation Inhibitor" (2023). Master's Theses. 4480.
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Copyright © 2023 Drew Hahnnah Landrowski
Available for download on Monday, July 21, 2025