Gonzalez-Loyola, A. | Search bioRxiv

bioRxiv2023

Specialized mesenteric lymphatic capillaries by-pass the mesenteric lymph node chain to transport peritoneal antigens directly into mediastinal lymph nodes.

Lymphatic vessels (LVs) are indispensable for tissue fluid homeostasis and immune cell trafficking. The network of LVs that channel fluids from the gut into mesenteric lymph nodes (MLN) has been recognized as the sole lymphatic system in the mesentery. Here we describe an alternative, functionally autonomous set of capillary mesenteric LVs (capMLVs) that by-pass the MLNs and drain directly into mediastinal LNs. CapMLVs develop perinatally from valves of collective mesenteric lymphatic vessels (colMLVs) in response to arterial endothelial cell-derived VEGF-C. Once extended, capMLVs detach from colMLVs to form an independent elongated network comprised of LYVE1+, CCL21+ endothelial cells. Avascular areas of the mesentery juxtaposed to capMLVs contain cell islets that express ACKR4. This CCL21-scavenging atypical receptor facilitates the migration of mesenteric phagocytes into capMLVs to be channeled directly into mediastinal LNs. This allows peritoneum-derived ominous antigens to be processed separately from alimentary antigens.

developmental biology↗

bioRxiv2021

c-MAF maintains the transcriptional program of enterocyte zonation and the balance of absorptive/intestinal secretory cell types

Small intestinal villi are structural and functional units uniquely adapted to the nutrient absorption in higher vertebrates. Villus enterocytes are organized in spatially resolved "zones" dedicated to specialized tasks such anti-bacterial protection, and absorption of amino-acids, carbohydrates and lipids. The molecular mechanisms specifying villus zonation are incompletely understood. We report that inactivation of transcription factor c-MAF, highly expressed in mature lower and mid-villus enterocytes, perturbed the entire villus zonation program, by increasing the expression of regulators of carbohydrate and bile acid metabolism and transport, while suppressing genes related to amino acid and lipid absorption. Maf inactivation under homeostatic conditions expanded tuft cells and led to compensatory gut lengthening, preventing body weight loss. However, delayed enterocyte maturation in the absence of Maf impaired body weight recovery after acute intestinal injury, resulting in reduced survival. Our results identify c-MAF as a novel regulator of small intestinal villus zonation program, while highlighting the importance of coordination between stem/progenitor and differentiation programs for intestinal regeneration. Summaryc-MAF is expressed in differentiated enterocytes. c-MAF loss alters enterocyte zonation leading to a compensatory gut remodelling and tuft cell expansion. Upon acute intestinal injury mice deficient for c-MAF cannot recover due to lack of nutrient transport and compensatory lengthening.

cell biology↗