699 - Enhanced Lymphatic Flow in a Collaborative Cross Mouse Model: A Platform for Studying Lymphatic Gain-of-Function in Disease

Publication Number: 1676.699

Kelly A. Orgel, University of North Carolina at Chapel Hill School of Medicine, Cary, NC, United States; Elizabeth S. Douglas, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States; Monserrat Avila-Zozaya, University of North Carolina, Chape Hill, NC, United States; Yanna Tian, UNC-CH, Chapel Hill, NC, United States; Natalie M. Torres-Valle, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States; Hannah R. Hrncir, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States; Laszlo Balint, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States; Kathleen M. Caron, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States

Background: The intestinal lymphatic system is imperative for maintaining fluid balance, immune surveillance, and lipid absorption. Despite research implicating the lymphatics in a number of inflammatory conditions, there have been a paucity of studies on the role of the lymphatics in neonatal development or disease. In order to best study the role of lymphatics, improved animal models are needed. The collaborative cross (CC) is a panel of recombinant inbred mouse strains that was generated by randomized breeding of 5 common and 3 wildtype founder strains, creating tremendous genetic and phenotypic variation.

Objective: Utilize the CC to characterize a novel mouse model of lymphatic gain-of-function and its influence on intestinal diseases in neonates.

Design/Methods: CC strains are generated using a funnel breeding method (Fig. 1A). A preliminary screen of 16 CC mouse strains was completed. All further studies focused on CC46, a strain with increased lymphatic flow rates. Lymphatic flow was measured by microlymphography, and fluorescence intensity per second was used to compare flow rate between CC46 mice (n=6) and C57BL/6J mice (n=5). Weight was measured weekly, and weight gain relative to baseline was compared between CC46 mice and controls on a high-fat diet (HFD) over a 3-week period. Mice were gavage-fed BODIPY-labeled fatty acid (BODIPY-C16), and immunofluorescence was performed on the small intestine after 3 hours to examine lipid absorption.

Results: A preliminary screen of 16 CC mouse strains identified CC46 as having the highest lymphatic flow rate. Further data confirmed CC46 mice had higher lymphatic flow rate compared to control mice (P < 0.01, Fig. 1B). Over a 3-week HFD, they also showed increased weight gain trajectory compared to controls (P < 0.0001 at 1 week, P < 0.01 at 2 weeks, and P < 0.05 at 3 weeks, Fig. 1C). Lastly, immunofluorescence staining showed typical lipid uptake in control enterocytes and lacteals (Fig. 1D), which was markedly reduced in enterocytes, and concentrated to the blood vascular compartment in CC46 mice (Fig. 1E), indicative of more rapid lipid absorption in CC46 compared to controls.

Conclusion(s): Our data demonstrate that the novel mouse strain CC46 has increased lymphatic flow rate compared to controls. Furthermore, this increased lymphatic flow rate leads to greater weight gain on HFD and a higher rate of lipid absorption. Based on our findings, CC46 mice provide a unique tool to study the effects of gain-of-lymphatic function in early development in intestinal diseases in neonates. Future studies will also map the genetic determinants of increased lymphatic flow rate.

Figure 1. CC46 mice have increased lymphatic flow rate and lipid absorption in the small intestine.
A. Funnel Breeding used to generate the Collaborative Cross. B. Lymphatic flow rate measured by microlymphography fluorescence intensity per second for control and CC46 mice. C. Weight change relative to baseline per week for controls and CC46 mice. D. Immunofluorescence of small intestine villi from control mice and E. CC46 mice 3 hours after BODIPY gavage administration.