Microthrombi growth in ADAMTS13 deficiency exacerbates inflammatory bowel disease via mucosal and endothelial dysfunction.

Abstract

BACKGROUND: Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by mucosal inflammation and ulceration. While von Willebrand factor, typically cleaved by ADAMTS13 from ultralarge multimers into smaller fragments, has been found to accumulate in the inflamed lesions of the ADAMTS13-deficient colitis model, the association between aberrant thrombus formation in lesional microvessels and colitis exacerbation remains unclear. OBJECTIVES: We investigated potential linkages between microthrombus formation and colitis progression. METHODS: Plasma and inflamed colonic tissues from patients with UC were analyzed. We employed intravital multiphoton microscopy to reveal the real-time structural dynamics of the mucus layer and mucosal vasculature at single-cell spatial resolution in a dextran sulfate sodium-induced colitis model of wild-type and ADAMTS13-deficient green fluorescent protein-expressing mice. RESULTS: Patients with UC exhibited significantly reduced plasma ADAMTS13 activity and excessive von Willebrand factor deposition in inflamed colonic tissues. In dextran sulfate sodium-induced colitis mice, ADAMTS13 deficiency showed heightened disease activity and increased mucosal erosion in histochemical analysis compared with wild-type mice. A novel methodology appraised colonic mucus barrier integrity by visualizing fluorescent dextran penetration from the colonic lumen to crypts. ADAMTS13 deficiency accelerated mucus layer disruption, leukocyte recruitment, and microthrombus formation, particularly in periepithelium regions. Vessel-specific analyses demonstrated that obstructive microthrombi were most prominent in the mucosal layer, contributing to local ischemia and mucosal erosion. Recombinant human ADAMTS13 alleviated microthrombus formation, improved mucosal integrity, and mitigated colitis severity in both wild-type and ADAMTS13-deficient mice. CONCLUSION: Advanced intravital imaging analysis revealed that obstructive thrombi formed in mucosal vessels due to impaired ADAMTS13 activity were essential for colitis severity.