The motivation of our project is to create a new model for therapeutic treatment that would use bioengineered E. coli probiotics for the targeted and controlled release of therapeutics in the colon. Specifically, we want to treat ulcerative colitis, a type of Inflammatory bowel disease (IBD). Our treatment could be applied to a variety of diseases local to the large intestine, including colon cancer. Furthermore, if this project succeeds, the plasmids can be transferred to other organisms and used in various organs to treat a larger variety of diseases.

This therapeutic model has profound implications, providing a realistic way to utilize the best aspects of bioengineered therapy in vivo. Our BOOMcoli are designed to be fast acting, highly specific, and low impact, a probiotic that can be taken when symptoms arise and quickly work to release targeted therapy in single, clean doses.

We plan on recognizing target cells by levels of calprotectin, and therefore levels of inflammation. Our engineered probiotic will also bind at sites along the colon and create a biofilm, localizing in areas of inflammation. Then we will utilize quorum sensing, a concentration-based way of bacterial communication. Once the concentration of bacteria is high enough (above a specific threshold set via promoter strength) to produce the signal necessary, the bacteria will respond by lysing in unison and releasing the respective therapeutic only in these targeted areas. Our project builds on ideas from last year’s Princeton iGEM team by applying the stick and secrete technology to the treatment of localized diseases such as cancer or IBD.

Autoimmune diseases occur when an individual's immune system targets its own body as opposed to protecting it, leading to inflammation and damage. Inflammatory bowel disease (IBD), which includes Crohn’s disease and Ulcerative colitis, is an autoimmune disorder characterized by chronic inflammation in the gastrointestinal (GI) tract, affecting about 1.6 million Americans with as many as 70,000 new cases a year. As the lining of the intestine becomes inflamed and ulcerated, it loses its ability to process food and waste or absorb water. Small sores form in the colon and rectum, which can result in ulcers and bloody stools, and blood loss can eventually lead to anemia if unchecked. Severe inflammation left for prolonged periods of time leads to patients having to surgically remove portions of their damaged GI, a common occurrence in 70% of patients with Crohn’s disease and 25% of patients with Ulcerative colitis. IBD complications of ulcers, anemia, and severe pain, significantly impact patients’ quality of life.

The cause of IBD is unknown, and therefore treatment of IBD focuses on the management of symptoms with a focus on the reduction of inflammation. The symptoms of IBD vary from person to person and change over time, ranging from mild to severe, with different periods of remission (few to no symptoms) and flares (active and with symptoms). Flares can be difficult to predict, and the current practice of monitoring the remission and flare of IBD is through endoscopy which is invasive, expensive, and requires medical expertise. Current treatments include regular administration of aminosalicylates, corticosteroids, or immunomodulators such as anti-TNF agents, which have many side effects due to systemic administration. Such treatments are costly with an average cost of $26,000 annually, and only have a success rate of 50%. Drugs that are immunosuppressive - often used for autoimmune diseases in general - have burdensome side effects due to the suppression of the immune system and make patients more prone to infectious disease, in addition to the risk of organ damage due to cumulative exposure.

The side effects and low success rate of current treatments for autoimmune conditions such as IBD are due to a lack of accuracy. Current treatments lack focus on the areas that actually become inflamed. Since IBD varies from person to person, it takes some trial and error to figure out when it is best to actually take medication to treat the inflammation.

Our plan involves translating our design into a practical application through a probiotic system. While our experiments have utilized stellar competent E. coli strains, our real-world implementation will employ the E. coli strain Nissle 1917, a non-pathogenic bacterium used in treating gastrointestinal disorders. This approach will allow patients with ulcerative colitis to benefit from our engineered probiotic, which will deliver E. coli directly to inflamed areas in the gut. This strain will then release IL-10, targeting inflammation effectively. Since our E. coli functions as a probiotic, it will be naturally expelled from the gut over time, ensuring that there is no risk of harmful bacteria persisting in the system. This method ensures a streamlined and safe therapeutic process.

Our project takes inspiration from the 2023 Princeton IGEM team and various studies on IBD treatments, bacterial lysis, and quorum sensing mechanisms. Inspired by the 2023 Princeton IGEM team's stick-and-secrete method for interkingdom communication between bacterial and mammalian cells, we began exploring how bacteria could interact with mammalian gut cells to release therapeutics and protect the gut microbiome. This exploration led us to consider bacterial lysis mechanisms and quorum sensing abilities as novel approaches for controlled therapeutic delivery.