Identifying Neutrophil Specific Mechanisms for Resistance to Biologics in Ulcerative Colitis

Abstract Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting approximately 1 million people in the United States. Annual healthcare expenditure for UC is estimated to be more than $10 billion dollars, with most of this cost being related to expensive biologic therapies. The two most prescribed biologics in UC are vedolizumab and adalimumab, however, efficacy for these advanced therapies plateaus at approximately 30%. Thus, there is an unmet need to understand drug specific mechanisms of treatment resistance. Our participant level patient data and observations in murine colitis/colon injury models indicate that persistence of distinct neutrophil subsets in the intra-epithelial space results in ongoing intestinal stem cell (ISC) injury, negatively impacting the epithelial crypt microenvironment and treatment efficacy for biologics. Thus, proposed studies will integrate clinical patient-focused and basic mechanism-focused studies to explore the idea that spatially distinct neutrophil populations with unique genetic signatures and function may dictate mechanism specific therapeutic response and impact mucosal injury resolution. In the first Aim using spatially resolved single-cell and sub-cellular high-plex digital quantification of mRNA and protein in already collected mucosal tissue from UC patients, we will profile neutrophils, T-cells, and intestinal epithelium based on spatial orientation (crypts vs lamina propria) in UC patients. Using this approach, we will identify gene/protein signatures predictive of response to vedolizumab therapy in UC and define targetable mechanisms through which epithelial neutrophils interact with crypts and T-cells to mediate non-response to vedolizumab. Second Aim will investigate how intra-epithelial neutrophil burden functionally impacts therapeutic responses and resolution of colon injury in murine colitis. Specifically, using murine colon injury/colitis models, clinically relevant therapeutics and neutrophil-specific genetic approaches, we will define molecular cues guiding neutrophil retention in the intra-epithelial space and how this unique spatial localization impacts therapeutic response to biologics (vedolizumab, adalimumab and tofacitinib). We will further determine whether intra- epithelial neutrophils exacerbate colon injury and impede therapeutic efficacy of vedolizumab through enhanced ISC loss. As such, studies outlined in the current proposal will identify new mechanisms of therapeutic resistance to biologics and identify molecular targets to optimize/improve responsiveness.