Lymphatic deletion of calcitonin receptor–like receptor exacerbates intestinal inflammation
Reema B. Davis, Daniel O. Kechele, Elizabeth S. Blakeney, John B. Pawlak, Kathleen M. Caron
Reema B. Davis, Daniel O. Kechele, Elizabeth S. Blakeney, John B. Pawlak, Kathleen M. Caron
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Research Article Gastroenterology

Lymphatic deletion of calcitonin receptor–like receptor exacerbates intestinal inflammation

Abstract

Lymphatics play a critical role in maintaining gastrointestinal homeostasis and in the absorption of dietary lipids, yet their roles in intestinal inflammation remain elusive. Given the increasing prevalence of inflammatory bowel disease, we investigated whether lymphatic vessels contribute to, or may be causative of, disease progression. We generated a mouse model with temporal and spatial deletion of the key lymphangiogenic receptor for the adrenomedullin peptide, calcitonin receptor–like receptor (Calcrl), and found that the loss of lymphatic Calcrl was sufficient to induce intestinal lymphangiectasia, characterized by dilated lacteals and protein-losing enteropathy. Upon indomethacin challenge, Calcrlfl/fl/Prox1-CreERT2 mice demonstrated persistent inflammation and failure to recover and thrive. The epithelium and crypts of Calcrlfl/fl/Prox1-CreERT2 mice exhibited exacerbated hallmarks of disease progression, and the lacteals demonstrated an inability to absorb lipids. Furthermore, we identified Calcrl/adrenomedullin signaling as an essential upstream regulator of the Notch pathway, previously shown to be critical for intestinal lacteal maintenance and junctional integrity. In conclusion, lymphatic insufficiency and lymphangiectasia caused by loss of lymphatic Calcrl exacerbates intestinal recovery following mucosal injury and underscores the importance of lymphatic function in promoting recovery from intestinal inflammation.

Authors

Reema B. Davis, Daniel O. Kechele, Elizabeth S. Blakeney, John B. Pawlak, Kathleen M. Caron

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Figure 2

Lymphatic loss of Calcrl is sufficient to cause dilated lacteals and submucosal lymphatics.

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Lymphatic loss of Calcrl is sufficient to cause dilated lacteals and sub...
(A–D) Representative images of lymphatic vessels stained with lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1) in the ilea of tamoxifen-treated (TAM-treated) Calcrlfl/fl and Calcrlfl/fl/Prox1-CreERT2 mice. n = 3 each group. Scale bar: 500 μm. Arrows point to dilated lymphatic vessels. (E–H) Representative whole mount LYVE1 and smooth muscle actin–stained (SMA-stained) ilea from TAM-treated Calcrlfl/fl and Calcrlfl/fl/Prox1-CreERT2 animals. Scale bar: 500 μm. Arrows point to dilated lymphatic vessels. (I) Simplified schematic indicating the plane of sectioning (dashed line) of villi for J–L. (J–L) LYVE1 staining of jejunal lymphatic vessels of untreated Calcrlfl/fl, TAM-treated Calcrlfl/fl, and Calcrlfl/fl/Prox1-CreERT2 animals. Arrows point to dilated lymphatic vessels toward the center of the villi. Scale bar: 1,000 μm. (M) The area of open lacteals normalized to the area of villi cross sections and expressed as a percentage. n = 3–5 mice per group, with 20–60 villi quantified per mouse. Quantitative data are represented as a box-and-whisker plot, with bounds from 25th to 75th percentile, median line, and whiskers ranging from minimum to maximum values for percentage lacteal area. Significance was determined by 1-way ANOVA with Tukey’s Multiple comparison test, *P < 0.05.