Disturbance of Lymphatic Function by Prox1 Contributes to Mesenteric Lesions and the Composition of Microbiota in Crohn’s Disease

INTRODUCTION: The main aim of the current study was to investigate the potential role of Prox1 in lymphatic function and analyze Prox1-dependent stimulation of lymphatic function in experimental Crohn's disease (CD). METHODS: Prox1flox/+, Tie2-CreERT2, and IL-10 KO mice were included. Lymphatic vessel density and lymphatic function were analyzed using immunohistochemistry and lymphangiography. The effects of lymphatic function on mesenteric adipose tissue (MAT) and the composition of microbiota were evaluated. Disease activity and enterocolitis inflammation were assessed using a grading system. RESULTS: For lymphatic vessel, IL-10 KO+Prox1 KO mice showed lower lymphatic vessel density and less functional lymphatic vessels. IL-10 KO+AAV-Prox1 mice showed significantly increased lymphatic vessel density. Delivery of AAV-Prox1 also promoted lymphatic drainage function. Additionally, Prox1-dependent stimulation of lymphatic function reduced hypertrophy of MAT in IL-10 KO mice. Delivery of AAV-Prox1 also modified the composition of microbiota; the proportion of Firmicutes increased and Bacteroidetes decreased in IL-10 KO+AAV-Prox1 mice compared with IL-10 KO mice. An increase in the diversity of gut microbiota in IL-10 KO+AAV-Prox1 mice was observed. Systemic delivery of AAV-Prox1 ameliorated disease activity index and the severity of gut inflammation in IL-10 KO mice. Without the compensatory response of Prox1, IL-10 KO+Prox1 KO mice developed serious inflammation in the colon. CONCLUSION: Prox1 played the critical role in lymphatic function. Additionally, Prox1-dependent stimulation of lymphatic function could reduce hypertrophy of MAT, modify the composition of microbiota, and ameliorate gut inflammation. Our findings demonstrated that correction of lymphatic function with Prox1 may lead to improved treatments for CD.