Team:UIUC Illinois/Project/Background Info

Cardiovascular disease and etiology
Many heart illnesses are deemed cardiovascular disease. Cardiovascular disease, also known as heart disease, is the medical term used to describe a slew of heart-related health problems, including myocardial infarctions, heart failure, and stroke. A major source of these problems is the onset of atherosclerosis, a condition characterized by the buildup of plaque in one’s arteries. There are a variety of causes of atherosclerosis, but our project addresses the proatherogenic substance trimethylamine-n-oxide, a metabolite of certain chemicals often found in red meat and energy drinks.

Gut Bacteria and Atheroscelosis
TMAO is the product of gut bacteria metabolism of L-carnitine. L-carnitine is essential to cellular processes, and the cells of the human body produce it as needed. It can begin to cause problems, however, when excessive amounts are present in one’s diet; typically it is found in high levels in red meat and energy drinks. Certain strains of bacteria found in the intestines break down L-carnitine into trimethylamine. The product trimethylamine is toxic to the human body and is therefore broken down by the liver into trimethylamine-n-oxide.

Current Treatments
The best way to avoid TMAO-induced atherosclerosis is to exercise moderation when consuming red meat and energy drinks. However, self-control alone is not the most effective method for promoting public health. There are no treatments to directly reverse the buildup of plaque once it has imbedded itself in the walls of arteries. In severe cases, bypass surgeries and stents are used to redirect and manage blood flow through the body. These procedures are rather invasive and come with long recovery times. The University of Illinois (UIUC) iGEM Team sought a better method for people to be able to eat the food they love while maintaining a healthier heart.

Gut Bacteria Ecology and Intervention
Most current treatments of atherosclerosis are not preventative. Our team looked to provide one such preventative treatment by halting the production of TMAO. Thousands of gut bacteria reside within the human digestive tract, and some L-carnitine loving bacteria found in the flora are responsible for converting L-carnitine into TMA.
Our strategy for combating the production of TMA is to make a probiotic that will outcompete the current gut flora for L-carnitine. This probiotic will then process the L-carnitine into a much less harmful product.

Genetically Modified Nissle 1917
Safety is always a major concern when introducing foreign organisms into the body, so we have chosen to work with Escherichia coli (E. coli) strain Nissle 1917 to start the platform of creating a safe probiotic. The Nissle strain is deemed safe-for-consumption and probiotic use by the United States Food and Drug Administration.
E. coli has a natural L-carnitine uptake system, but to outcompete the pre-existing gut bacteria, we decideded to genetically modify our strain. The genes CaiX and CbcVW were selected to be implemented into our bacteria from Pseudomonas Aeruginosa, a bacterium with unique adaptations for L-carnitine uptake and processing.
Additionally, in order to break down the L-carnitine, we introduced the CDH gene from P. Aeruginosa into our Nissle cells. This gene encodes for L-carnitine dehydrogenase, a protein that metabolizes L-carnitine along a safer alternative pathway.

Cardiobiotics With our genetic parts, our Cardiobiotics present a never-before-seen application of synthetic biology to the field of cardiovascular health. Our engineered bacteria can uptake L-carnitine and divert it along pathway toward the end product of glycine-betaine, a much less harmful product than TMAO.