The Transforming Growth factor β (TGFβ) signaling pathway is a key player in a variety of cellular functions. Excessive stimulation and mutations in the TGFβ pathway, however, can promote the development of fibrosis and tumorigenesis due to pathogenic fibroblast proliferation and matrix remodeling. I have used a robust in vitro assay to characterize the TGFβ-induced phenotypic differentiation and matrix remodeling of a human primary lung fibroblast cell line, CCD19Lu. By comparing the phenotype of CCD19Lu cells and the composition and structural remodeling of the extracellular matrix they produced in the presence and absence of exogenous TGFβ, I demonstrated that TGFβ drives a fibrogenic transitional myofibroblast phenotype – characterized by positivity for fibroblast activation protein (FAP) and α-smooth muscle actin (αSMA) in fibroblast-derived matrix (FDM)-generating conditions. Additionally, I found that TGFβ induced increased cytoskeletal stress fiber formation and production of a more fibrotic-like matrix. 

While TGFβ serves as an enticing target for therapeutic treatments of solid tumors and tissue fibrosis, the pleiotropic effects of TGFβ especially in the context of solid tumors presents a significant challenge. Hence, I focused on selectively inhibiting TGFβ Receptor II (TGFβRII) on FAP+ fibroblasts through the addition of a bispecific antibody targeted to TGFβRII and FAP. This allowed me to investigate how TGFβ impacts matrix formation in a reductionist approach in an in vitro setting. Through the utilization of bispecific antibodies, I discovered that this fibrogenic response driven by TGFβ can be partially neutralized upon the addition of antibodies targeting TGFβRII. 

The results of my experiments were the development of a robust in vitro assay that characterized the fibrogenic programming and reprogramming of fibroblasts and their respective matrices in the presence of TGFβ and the potential to reverse these effects using a targeted reagent.