Pattern Recognition Receptors (PRRs) are a group of evolutionarily conserved and germline-encoded cellular receptors of the innate immune system that are responsible for recognizing and responding to the entirety of the pathogens a host encounters. The ingenuity of the innate immune system is that with a comparatively miniscule pool of receptors, these receptors are capable of responding to a diverse and large array of pathogens and damage signals. Two highly relevant subsets of PRRs include nucleotide binding domain leucine rich repeat containing (NOD-like) receptors (NLRs) and Toll-like receptors (TLRs). Both NLRs and TLRs have been implicated in several diseases, including autoimmune disorders, inflammatory conditions, and cancer. Mice lacking a specific NLR, NLRP1, are more susceptible to chemically induced colitis and colitis-associated tumorigenesis. We investigated whether the absence of NLRP1 in the gastrointestinal tract influenced the composition of the microbiome, and whether it was responsible for the predisposition of these animals to colitis-associated cancer. By carefully controlling for non-genotype influences, we found that in fact maternal and housing factors were greater predictors over genotype of gut flora composition. This study concluded with a clearer understanding of NLRP1. We next investigated the effectiveness of a novel tumor ablation therapy, termed High-Frequency Irreversible Electroporation (H-FIRE) in a murine model of triple negative breast cancer. The chosen 4T1 model closely mimics aggressive human metastatic triple negative breast cancer, and metastasizes to the same organs. After ablation of the primary mammary tumor, we saw significant improvements in disease burden and metastases, both of which were accompanied by PRR activation within the tumor microenvironment, implicating PRRs in the successful treatment outcome following H-FIRE ablation. Lastly, we generated novel CRISPR-Cas9 plasmids to genetically manipulate the Tlr4 gene of wild type C57Bl/6 mice in order to recapitulate the LPS-hyporesponsive TLR4 protein of C3H/HeJ mice. This proof-of-concept study successfully demonstrated that PRRs can be targets for gene editing purposes, and that nanoparticle delivery leads to enhanced and improved delivery. Collectively, this work attempts to better appreciate the role of PRRs in understanding, treating, and targeting cancer. / Doctor of Philosophy / The work presented here focuses on the role of the immune system in the progression of cancer. Put simply, the properly functioning immune system of a healthy individual should recognize and eliminate mutated or cancerous cells prior to the development of a tumor, thereby implying that the progression to a tumor is due to some dysfunction of the immune system. The immune system is made up of two arms: the innate and adaptive. A key difference between the innate and adaptive immune systems is that upon an infection, the adaptive response is slow and specific while the innate response is rapid and broad. Pattern Recognition Receptors (PRRs) are a group of cellular receptors of the innate immune system that are responsible for recognizing and responding to the entirety of the pathogens a host encounters. The ingenuity of the innate immune system is that with a comparatively miniscule pool of receptors, these receptors are capable of responding to a diverse and large array of pathogens. Two highly relevant PRR families are nucleotide binding domain leucine rich repeat containing (NOD-like) receptors (NLRs) and Toll-like receptors (TLRs). Both NLRs and TLRs have been implicated in several diseases, including autoimmune disorders, inflammatory conditions, and cancer.
In this work, we investigated whether the absence of an NLR protein influenced the composition of the microbes that reside within the gastrointestinal tract, and whether this absence was responsible for the predisposition of these animals to colitis-associated cancer. By carefully controlling for all additional influences, we found that in our mice, the other animals with which they shared a cage were more influential on the microbes within the gut, rather than the NLR deficiency. We next investigated a novel tumor ablation therapy in an animal model of breast cancer, which closely mimics human metastatic triple negative breast cancer and metastasizes to the same organs. After treatment of the mammary tumor, we saw significant improvements in disease burden and metastases, both of which were accompanied by PRR activation. Lastly, we manipulated a TLR gene in mice to demonstrate that PRRs can be targeted for therapeutic gene editing. Collectively, this work provides evidence that PRRs are a highly useful tool for improving our understanding of cancer.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/100587 |
| Date | 23 April 2019 |
| Creators | Scaia, Veronica Marie |
| Contributors | Graduate School, Allen, Irving C., Schmelz, Eva M., Davis, Richey M., Dervisis, Nikolaos G., Oestreich, Kenneth |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf, video/mp4, video/mp4 |
| Rights | Creative Commons Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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