Moecular Profiling of Blood for Diagnostics and Discovery

Abstract

Every cell of the body has the opportunity to secrete molecules into the blood. These molecules: proteins, RNAs, and DNAs, can be secreted freely, or within extracellular vesicles (EV). The complement of specific molecules secreted by cells can vary in accordance with changes to their immediate environment, such as disease in a particular organ. Cells of the immune system which circulate in the blood may also change the rates at which they produce these molecules in response to a disease or unusual event occurring somewhere within the body. The full complement of proteins, RNAs, or DNAs from all sources within the blood can therefore be measured to garner information about disease states and communication between every tissue of the body. In this body of work, we leveraged this to address three separate challenges within medical science. First, we utilized blood as a source of biomarkers for disease and disease severity; isolating EVs from the blood of prostate cancer patients and healthy subjects and characterized their proteins with mass spectrometry to identify potential biomarkers for prostate cancer and its stages. Next, we explored the ability of blood to identify commonalities between distinct but often comorbid diseases; here we utilized publicly available datasets to identify transcripts or gene sets potentially facilitating the relationship between PTSD, MDD, and asthma. Finally, we utilized differential gene and gene sets expression to gain mechanistic insight into microbiota-gut-brain axis; investigating the hippocampus and blood of mice fed one of two psychobiotic bacteria: Lactobacillus rhamnosus JB1, Lactobacillus reuteri 6475. The analysis identified several mRNA expression differences potentially responsible for the mood-altering characteristics of these psychobiotic bacteria. This body of work illustrates the utility of blood omics data for addressing many problems within medical science, and highlights the large scale of information stored within the blood.