The Wechsler Laboratory has several translational research projects focused on characterizing the pathogenesis of EoE and identifying novel predictors of treatment response, particularly diet elimination. Notably, the immune response in EoE involves an interaction between T-lymphocytes, mast cells, eosinophils, and epithelial cells. The lab utilizes a large clinical database, biorepository of tissue and blood on which they perform single cell and bulk transcriptome analysis, blood/plasma-based assays, immunohistochemistry/immunofluorescence with semi-automated image capture/analysis. In addition, they use human primary cells and murine cells to perform ex vivo/in vitro immune cell culture and 3-D modeling of esophageal epithelium to identify mucosal factors critical to the pathogenesis of EoE-associated inflammation with regards to the interaction of these cell types, and the antigen-specific nature of the disease.
ROLE OF MAST CELL ACTIVATION IN EOSINOPHILIC ESOPHAGITIS
Preliminary data from my laboratory suggests that mast cell inflammation may persist despite low eosinophil counts in a subset of patients with endoscopic furrows, and histologic epithelial reactive changes. The type of mast cell involved in this along with the pathologic consequences are unclear.
We have detected the presence of tryptase-positive/carboxypeptidase A3-negative and tryptase/carboxypeptidase A3-positive mast cells in the epithelium of EoE patients by multi-color immune-fluorescence. My laboratory is investigating the phenotypic changes in mast cell type and density that occur with treatment using the Nikon Imaging Facility.
To understand the consequences of mast cell activation on epithelial tissue, in vitro experiments with EoE and non-EoE derived cell lines grown in 3-D culture to mimic the surface tissue (epithelial) layer. We are working in collaboration with Marie-Pier Tetrault, Ph.D. to study this similarly in pediatric biopsy-derived organoids. We are studying the consequences of mast cell activation utilizing primary Human Mast Cells (HuMCs) and specific mast cell mediators on epithelial barrier function, cell proliferation and differentiation.
We are performing single-cell RNA-Sequencing in collaboration with Katie Hulse, Ph.D., on patient biopsies samples prospectively before and after treatment to understand the changes in the mast cell transcriptome. Biopsies specimens are dispersed into single cell suspensions and captured in an oil bubble where single cell RNA-derived libraries are created with individual molecular identifiers and sequenced. We are collecting validated surveys regarding quality of life and symptoms along with endoscopic and histologic scoring that will be correlated with the individual mast cell transcriptome.
BIOMARKERS OF DIET ELIMINATION RESPONSE IN EOSINOPHILIC ESOPHAGITIS
Preliminary data from my laboratory using bulk RNA-Sequencing on formalin-fixed paraffin embedded esophageal biopsies has identified unique tissue transcriptomic signatures that predict single vs multiple food inflammation triggers in EoE patients undergoing diet elimination therapy.
We are performing bulk and single-cell RNA analysis, in collaboration with Katie Hulse, Ph.D. and the Northwestern University Sequencing Core (NuSeq), of prospectively collected EoE patient biopsies before and after diet elimination, and during food reintroduction, to identify molecular biomarkers of the diet elimination treatment response. We are performing assays on plasma from blood specimens collected at the time of endoscopy.
ROLE OF HISTAMINE 4-RECEPTOR IN ULCERATIVE COLITIS
We have recently published evidence of a role for mast cell-derived histamine and H4R in recruiting neutrophils and eosinophils to the colonic mucosa. We have created a EMR cohort of control and UC patients that have undergone diagnostic colonoscopy. Preliminary evidence from the laboratory supports increased H4R-positive eosinophils and neutrophils, but not mast cells in UC patients compared to controls in the rectum. These cells correlated with clinical markers of disease activity. We are currently investigating the changes that occur in the transition zone in H4R eosinophils, neutrophils, and mast cells, along with the correlation with clinical parameters. In addition, we are performing functional assays to quantify the functional role of H4R on murine eosinophils and neutrophils in the context of IL-6 and neutrophilic chemokines CXCL1 and CXCL2.