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Xerostomia and the Microbiome of the Mouth

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Is it possible to treat the mouth as a natural environment, and determine new methods to keep the microbiome in check? The need for biodiversity in health may suggest that every species carries out a specific function that is required

Is it possible to treat the mouth as a natural environment, and determine new methods to keep the microbiome in check? The need for biodiversity in health may suggest that every species carries out a specific function that is required to maintain equilibrium and homeostasis within the oral cavity. Furthermore, the relationship between the microbiome and its host is mutually beneficial because the host is providing microbes with an environment in which they can flourish and, in turn, keep their host healthy. Reviewing examples of larger scale environmental shifts could provide a window by which scientists can make hypotheses. Certain medications and healthcare treatments have been proven to cause xerostomia. This disorder is characterized by a dry mouth, and known to be associated with a change in the composition, and reduction, of saliva. Two case studies performed by Bardow et al, and Leal et al, tested and studied the relationships of certain medications and confirmed their side effects on the salivary glands [2,3]. Their results confirmed a relationship between specific medicines, and the correlating complaints of xerostomia. In addition, Vissink et al conducted case studies that helped to further identify how radiotherapy causes hyposalivation of the salivary glands [4]. Specifically patients that have been diagnosed with oral cancer, and are treated by radiotherapy, have been diagnosed with xerostomia. As stated prior, studies have shown that patients having an ecologically balanced and diverse microbiome tend to have healthier mouths. The oral cavity is like any biome, consisting of commensalism within itself and mutualism with its host. Due to the decreased salivary output, caused by xerostomia, increased parasitic bacteria build up within the oral cavity thus causing dental disease. Every human body contains a personalized microbiome that is essential to maintaining health but capable of eliciting disease. The Human Oral Microbiomics Database (HOMD) is a set of reference 16S rRNA gene sequences. These are then used to define individual human oral taxa. By conducting metagenomic experiments at the molecular and cellular level, scientists can identify and label micro species that inhabit the mouth during parasitic outbreaks or a shifting of the microbiome. Because the HOMD is incomplete, so is our ability to cure, or prevent, oral disease. The purpose of the thesis is to research what is known about xerostomia and its effects on the complex microbiome of the oral cavity. It is important that researchers determine whether this particular perspective is worth considering. In addition, the goal is to create novel experiments for treatment and prevention of dental diseases.

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Date Created
2015-05

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Frameshift antigens for cancer vaccine development

Description

Immunotherapy has been revitalized with the advent of immune checkpoint blockade

treatments, and neo-antigens are the targets of immune system in cancer patients who

respond to the treatments. The cancer vaccine field is focused on using neo-antigens from

unique point mutations of genomic

Immunotherapy has been revitalized with the advent of immune checkpoint blockade

treatments, and neo-antigens are the targets of immune system in cancer patients who

respond to the treatments. The cancer vaccine field is focused on using neo-antigens from

unique point mutations of genomic sequence in the cancer patient for making

personalized cancer vaccines. However, we choose a different path to find frameshift

neo-antigens at the mRNA level and develop broadly effective cancer vaccines based on

frameshift antigens.

In this dissertation, I have summarized and characterized all the potential frameshift

antigens from microsatellite regions in human, dog and mouse. A list of frameshift

antigens was validated by PCR in tumor samples and the mutation rate was calculated for

one candidate – SEC62. I develop a method to screen the antibody response against

frameshift antigens in human and dog cancer patients by using frameshift peptide arrays.

Frameshift antigens selected by positive antibody response in cancer patients or by MHC

predictions show protection in different mouse tumor models. A dog version of the

cancer vaccine based on frameshift antigens was developed and tested in a small safety

trial. The results demonstrate that the vaccine is safe and it can induce strong B and T cell

immune responses. Further, I built the human exon junction frameshift database which

includes all possible frameshift antigens from mis-splicing events in exon junctions, and I

develop a method to find potential frameshift antigens from large cancer

immunosignature dataset with these databases. In addition, I test the idea of ‘early cancer

diagnosis, early treatment’ in a transgenic mouse cancer model. The results show that

ii

early treatment gives significantly better protection than late treatment and the correct

time point for treatment is crucial to give the best clinical benefit. A model for early

treatment is developed with these results.

Frameshift neo-antigens from microsatellite regions and mis-splicing events are

abundant at mRNA level and they are better antigens than neo-antigens from point

mutations in the genomic sequences of cancer patients in terms of high immunogenicity,

low probability to cause autoimmune diseases and low cost to develop a broadly effective

vaccine. This dissertation demonstrates the feasibility of using frameshift antigens for

cancer vaccine development.

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Agent

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Date Created
2018