Abstract Introduction Ulcerative colitis (UC) and Crohn’s disease (CD) are types of inflammatory bowel disease (IBD), a chronic inflammatory condition in which the gut epithelium is continually damaged and unable to fully repair itself. Many types of immune cells, including neutrophils, macrophages, and T cells, can contribute to this damage. Several signaling pathways have been implicated in IBD, including the JAK/STAT pathway, which can be aberrantly activated. STAT1 and STAT3 are key members of the pathway frequently activated in IBD. Activation of STAT1 drives inflammation, but activation of STAT3 can have pro- or anti-inflammatory effects depending on the cellular context. Methods Using normal, CD, and UC tissue samples from human and mouse colon, we performed a SignalStar® multiplex immunohistochemistry experiment to characterize active, or phosphorylated, STAT3 and STAT1 (p-STAT3, p-STAT1) as well as phenotyping markers to identify epithelial cells and subsets of immune cells: regulatory T cells, Th1 cells, neutrophils, and M1- and M2-like macrophages. Results We did not detect p-STAT1+ cells in human tissues but observed a dramatic increase in p-STAT1+ cells in mouse UC compared to normal colon. p-STAT3+ cells were present in both human and mouse tissues but displayed more subtle differences. Many p-STAT3+ cells were not labeled by the phenotyping readouts in the panel, but we did observe p-STAT3+FoxP3+ and p-STAT3+MPO+ cells in human CD and UC. In mouse UC, we detected p-STAT3+ cells positive for F4/80, CD86, and CD206. Phenotypic trends in human IBD included increased numbers of MPO+, CD3+, FoxP3+, and CD206+ cells, while the most striking change in mouse tissue was the increase in F4/80+ cells in UC. Conclusion Although we did not phenotype all p-STAT3+ cells, we were able to determine that the p-STAT3+ cells were primarily non-epithelial cells, including macrophages and neutrophils; STAT3 inhibition may represent a therapeutic approach for treating IBD. Funding Source N/A Topic Categories Cellular Adhesion, Migration, and Inflammation (CAM)
MacDonald et al. (2026) studied this question.