ET-3/ETBR Mediates Na⁺-Activated Immune Signaling and Kidney Lymphatic Dynamics

Background: Lymphatic collecting vessels in the kidney are critical in clearing interstitial fluid, macromolecules, and infiltrating immune cells. Dysfunction of the lymphatic vessels can disrupt this process and exacerbate injury-associated inflammation in many disease conditions. We previously found that sodium accumulates within the kidney interstitium during proteinuric kidney injury and elevated sodium environments stimulate isolevuglandin production in antigen-presenting cells, stimulating T cells, and modulating inflammatory responses. In the present study, we investigated whether proteinuric injury increases production of isolevuglandin-adduct formation in antigen-presenting cells, their effects on lymphatic endothelial cells (LECs), and the role of the ET-3 (endothelin-3)/ETBR (endothelin type B receptor) on lymphatic vessel function.

Methods: We used a mouse model of nephrotoxin-induced proteinuric injury to show that proteinuric injury expanded the kidney lymphatic network and to immunophenotype the infiltrating immune cells. To determine mechanisms, we analyzed the interaction of migratory immune cells and LECs using an in vitro transwell migration assay, bulk RNA sequencing, and flow cytometric analysis. To determine the effect of ET-3/ETBR axis on lymphatic vessel contractility, we analyzed microdissected lymphangions utilizing a vessel perfusion chamber.

Results: We found that animals with proteinuric injury have increased kidney lymphangiogenesis, isolevuglandin-producing dendritic cells, and IFN (interferon)-γ-producing CD4+T cells. The sodium avid environment present in kidney injury enhances the interaction between LECs and migratory antigen-presenting cells and LEC production of isolevuglandin-adducts. Elevated sodium environment-induced isolevuglandin-adduct formation facilitates the ET-3/ETBR communication between LECs and dendritic cells. In addition, the ET-3/ETBR axis modulates lymphatic collecting vessel pumping dynamics.

Conclusions: These findings reveal a novel mechanism linking the isolevuglandin-mediated ET-3/ETBR axis with LECs and infiltrating dendritic cells. ET-3/ETBR signaling in lymphatic vessel dynamics is a novel pathogenic component and a possible therapeutic target in kidney disease.