Characteristics of Multi-Organ Lymphangiectasia Resulting from Temporal Deletion of Calcitonin Receptor-Like Receptor in Adult Mice

Abstract

Adrenomedullin (AM) and its receptor complexes, calcitonin receptor-like receptor (Calcrl) and receptor activity modifying protein 2/3, are highly expressed in lymphatic endothelial cells and are required for embryonic lymphatic development. To determine the role of Calcrl in adulthood, we used an inducible Cre-loxP system to temporally and ubiquitously delete Calcrl in adult mice. Following tamoxifen injection, Calcrlfl/fl/CAGGCre-ER™ mice rapidly developed corneal edema and inflammation that was preceded by and persistently associated with dilated corneoscleral lymphatics. Lacteals and submucosal lymphatic capillaries of the intestine were also dilated, while mesenteric collecting lymphatics failed to properly transport chyle after an acute Western Diet, culminating in chronic failure of Calcrlfl/fl/CAGGCre-ER™ mice to gain weight. Dermal lymphatic capillaries were also dilated and chronic edema challenge confirmed significant and prolonged dermal lymphatic insufficiency. In vivo and in vitro imaging of lymphatics with either genetic or pharmacologic inhibition of AM signaling revealed markedly disorganized lymphatic junctional proteins ZO-1 and VE-cadherin. The maintenance of AM signaling during adulthood is required for preserving normal lymphatic permeability and function. Collectively, these studies reveal a spectrum of lymphatic defects in adult Calcrlfl/fl/CAGGCre-ER™ mice that closely recapitulate the clinical symptoms of patients with corneal, intestinal and peripheral lymphangiectasia.

Lymphatic deletion of calcitonin receptor–like receptor exacerbates intestinal inflammation

“…Global deletion of the gene coding for the AM receptor, Calcrl, has been shown to induce multiorgan lymphangiectasia, resulting from dilated lymphatic vessels across several vascular beds (23). Since Calcrl is commonly expressed in several cell types, including cells outside the vasculature, to distinguish the role of Calcrl in lymphatic cells compared with its role in other cell types in contributing to lymphangiectasia, we deleted Calcrl from the adult mouse lymphatic endothelium.…”

“…These signaling partners are crucial for embryonic development since genetic deletion of Calcrl, Adm, or Ramp2 causes midgestation lethality due to arrested lymphangiogenesis in mice (20)(21)(22). In adult mice, the inducible, global genetic deletion of the Calcrl gene causes systemic lymphatic insufficiency in a multitude of lymphatic vascular beds, leading to corneal edema, distal limb edema, and lymphangiectasia (23). Since CLR is expressed in many cell types and tissues, we developed a genetic mouse model with inducible deletion of the Calcrl gene in lymphatic endothelium.…”

Rapamycin reversal of VEGF-C–driven lymphatic anomalies in the respiratory tract

“…Other models involving gene deletions or implantation of cells from human lymphatic malformations have been used to mimic human lymphatic disorders (37)(38)(39)(40). These models have proven useful in characterizing these conditions but are yet to be used to study the regression of abnormal lymphatics.…”

Schlemm’s canal: more than meets the eye, lymphatics in disguise

“…Immunohistochemical staining to characterize the ECs of SC revealed that they were positive for certain lymphatic and blood endothelial markers, including PROX1, integrin α9, CD31, lin, exhibited corneal edema, inflammation, and dilated corneoscleral lymphatic vessels (12). Earlier this year, Truong et al discovered high expression of the lymphatic transcription factor prospero-related homeobox 1 (PROX1) on SC endothelium in the eye (13), linking expression of the lymphatic fate determinant PROX1 to a structure within the eye.…”