Date of Award
11-16-2023
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Microbiology and Immunology
First Advisor
Liang Qiao
Abstract
Innate immunity represents the first line of defense against pathogens that invade our bodies. It greatly relies on a family of abundant receptors called pathogen recognition receptors (PRRs). These are germ-line encoded proteins abundant in immune cells like macrophages, dendritic cells, and natural killer cells. PRRs encompass five categories, one of which includes toll-like receptors (TLRs). TLRs could either be located on the surface of the cells or intracellularly. The mechanism by which TLRs act is through recognizing a myriad of foreign structures derived from microbes, such as proteins, lipids, and carbohydrates as well as their genetic material. Generally, these structures are known as pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Upon engagement of TLRs with PAMPs and formation of TLR-PAMP complex, downstream signaling cascade takes place through canonical NF-κB pathway or non-canonical NF-κB pathway, leading to the production of inflammatory cytokines, such as TNF-α and IL-6, which are crucial for mediating the signs of inflammation and activation of adaptive immunity. Additionally, nod-like receptors (NLRs) could recognize (DAMPs), leading to inflammasome assembly and subsequent caspase activation, culminating in the production of cytokines like IL-1β, IL-18, and cellular pyroptosis. Dysregulation of innate immune reactions could lead to developing diseases such as dry eye disease. Lactobacillus bacteria are probiotic bacteria that can reduce inflammation. In this study, we investigated the role of ‘JE,’ a metabolite isolated from Lactobacillus bacteria, in modulating innate immune responses. We tested JE’s effects on activation of murine macrophages with TLR agonists: LPS, flagellin, PAM-CSK, Imiquimod, FSL, Poly: IC, and ODN by determining the production of pro-inflammatory cytokines TNF-α and IL-6 by ELISA. Additionally, we also tested activation of NLRP3 inflammasome by determining the production of IL-1β by ELISA and caspase-1 activation by Western blot analyses. Moreover, we quantified the amount of NF-κB p65 in the cells in response to TLR activation in the presence of JE. Finally, we tested JE’s effect in a dry eye disease mouse model. Our data have demonstrated that JE decreased TNF-α and IL-6 production and diminished IL-1β production and caspase-1 activation upon NLRP3 stimulation in macrophages. It reduced the amount of activated p65 NF- κB formed in response to LPS stimulation and mitigated the severity of dry eye disease. Thus, the probiotic metabolite has anti-inflammatory effects.
Recommended Citation
Noufal, Rim Ahmed, "Investigating the Role of the Metabolite Je as an Inflammatory Modulator" (2023). Master's Theses. 4508.
https://ecommons.luc.edu/luc_theses/4508
