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 1

Loss of Calcrl using Prox1-CreERT2 leads to reduced weight gain and protein loss.

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Loss of Calcrl using Prox1-CreERT2 leads to reduced weight gain and prot...
(A) Relative expression of Calcrl in lungs of tamoxifen-treated (TAM-treated) Calcrlfl/fl and Calcrlfl/fl/Prox1-CreERT2 mice. 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 of fold change over Calcrlfl/fl controls; n = 7–8 animals in each group. Gapdh was used as housekeeping control. Significance was determined by 2-tailed, type 2 Student’s t test, **P < 0.01. (B) Relative expression of Calcrl in intestinal enterocyte and nonenterocyte population of TAM-treated WT/Prox1-CreERT2/Rpl22tm1.1Psam and Calcrlfl/fl/Prox1-CreERT2/Rpl22tm1.1Psam mice. 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 of normalized fold change over WT/Prox1-CreERT2/Rpl22tm1.1Psam controls (dashed line); n = 3 animals in each group. Gapdh was used as housekeeping control. Significance was determined by 2-way ANOVA, ***P < 0.001. (C and D) Measurement of weight loss (C) and serum albumin (D) in Calcrlfl/fl and Calcrlfl/fl/Prox1-CreERT2 mice after TAM treatment. 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 weight loss (C) and serum albumin (D). n = 5 for Calcrlfl/fl and 4 for Calcrlfl/fl/Prox1-CreERT2 group. Significance was determined by 2-tailed, type 2 Student’s t test, *P < 0.05.