Publication Date

Fall 2010

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Advisor

Daniel Holley

Subject Areas

Physiology

Abstract

Patients with inflammatory bowel disease (IBD) have increased numbers of numbers of intestinal mast cells (MCs). Chymases and tryptases are mast-cell-specific proteases (MCPs) that are reliable indicators of MC degranulation. The role of MCs in the pathophysiology of IBD is poorly understood, and it is unclear whether MCs play a role in patients or in experimental models of IBD. Furthermore, MCs have been characterized only in chemically induced models of colitis. In this study, we characterize MCs in inflamed colons of keratin 8 knock-out mice (K8-/-), a spontaneous model of colitis with primarily an epithelial cell defect. We used histologic, quantitative PCR (qPCR) and western blot analysis to quantify the increase in MCs and MCPs. Using chloroacetate esterase (CAE) tissue staining, we showed a statistically significant increase (p<0.05) in MCs in the colon of K8-/- mice as compared to their wildtype littermates, 2,4-dinitrofluorobenzene (DNFB)-treated, and dextran sodium sulfate (DSS)-treated mice colons. K8-/- colons showed an increase in all MCPs tested (MCP-1, -2, -4, -5, -6, and -7). In addition, at the protein level, both chymase and tryptase were over-expressed in K8-/- colons. In conclusion, absence of K8 was associated with a chronic colitis and with marked MC infiltration. Consistent with the increase in MCs, increased expression of MCPs were noted at the mRNA and protein levels. K8-deficient mice provide a model for studying the role of MCs in IBD.

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