Joshua’s work focused on the development of tissue engineered systems that incorporate the epithelium, immune system, and bacteria. His dissertation is titled “Development of in vitro models of the intestinal microbiota-epithelial-immune axis”.
Abstract: The influence of the intestinal environment on the systemic health of the human body cannot be overstated, with effects seen in developmental, neurological, cardiac, and oncological disorders, among others, motivating the development of multiple models to study various aspects of the interactions between the intestinal microbiota, epithelium, and immune system with various degrees of complexity. This thesis explores the development of in vitro models, from static cell line co-cultures to profused primary cell cultures, and reports on novel findings that can inform the further development and application of these systems. We first examine the deleterious impact of host oxidative species production on epithelial survival in static cell line co-cultures with live bacteria, as well as the partial mitigation of damage through the supplementation of an antioxidant, leading to one of the longest reported static co-culture of epithelial cell line monolayers with live bacteria. We then explore the differential response of cell line and primary ileal co-cultures to bacteria under flow and static conditions, finding that primary cultures can tolerate live bacteria under static and flow conditions with no deleterious effects, likely due to their ability to secrete sufficient amounts of mucin to protect the epithelial and immune cells. Meanwhile perfusion of cell line cultures works to reduce oxidative damage and prevent monolayer destruction, while also removing immune stimulating factors, reducing inflammatory cytokine production. Finally, the ability to develop in vitro patient derived disease models is demonstrated, using ileal cells with a genetic risk factor for Crohn’s Disease. We find these cells show increased permeability and promote an inflammatory immune environment, recapitulating in vivo models and clinical findings. In addition, an altered mucus composition is observed, potentially shedding insight on the genesis of clinical symptoms. Altogether, these methods and applications provide a foundation upon which research can be conducted for further insights into the vital microbiota-epithelium-immune axis.
We will miss him, but he will of course forever be a part of our lab family 🙂