Excessive TGF-b signaling in epithelial cells, pericytes, or fibroblasts has been implicated in CKD. This list has recently been joined by endothelial cells (ECs) undergoing mesenchymal transition. Although several studies focused on the effects of ablating epithelial or fibroblast TGF-b signaling on development of fibrosis, there is a lack of information on ablating TGF-b signaling in the endothelium because this ablation causes embryonic lethality. We generated endothelium-specific heterozygous TGF-b receptor knockout (TbRII endo+/2 ) mice to explore whether curtailed TGF-b signaling significantly modifies nephrosclerosis.These mice developed normally, but showed enhanced angiogenic potential compared with TbRII endo+/+ mice under basal conditions. After induction of folic acid nephropathy or unilateral ureteral obstruction, TbRII endo+/2 mice exhibited less tubulointerstitial fibrosis, enhanced preservation of renal microvasculature, improvement in renal blood flow, and less tissue hypoxia than TbRII endo+/+ counterparts. In addition, partial deletion of TbRII in the endothelium reduced endothelial-to-mesenchymal transition (EndoMT). TGF-b-induced canonical Smad2 signaling was reduced in TbRII +/2 ECs; however, activin receptor-like kinase 1 (ALK1)-mediated Smad1/5 phosphorylation in TbRII +/2 ECs remained unaffected. Furthermore, the S-endoglin/L-endoglin mRNA expression ratio was significantly lower in TbRII +/2 ECs compared with TbRII +/+ ECs. These observations support the hypothesis that EndoMT contributes to renal fibrosis and curtailing endothelial TGF-b signals favors Smad1/5 proangiogenic programs and dictates increased angiogenic responses. Our data implicate endothelial TGF-b signaling and EndoMT in regulating angiogenic and fibrotic responses to injury.

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Endothelial glycocalyx (EG) is disintegrated during sepsis. We have previously shown that this occurs very early in the course of sepsis and its prevention improves the survival of mice with sepsis. Here, we sought to investigate the possibility of pharmacologically accelerating the restoration of disintegrated EG in sepsis. We used a soilage injection model to induce polymicrobial sepsis in C57/BL6 mice and measured total body EG. En face aortic preparations were used for staining of markers of EG and atomic force microscopy was used to measure EG in vitro. In vitro studies were conducted in cultured endothelial cells either exposed to a lipopolysaccharide or enzymatically denuded of EG. Sulodexide (SDX), a heparin sulfate-like compound resistant to degradation by heparanase, accelerated EG regeneration in vitro and in vivo. The total volume of EG was drastically reduced in septic mice. Administration of SDX produced a dramatic acceleration of EG restoration. This effect, unrelated to any SDX-induced differences in microbial burden, was associated with better control of vascular permeability. Notably, SDX demonstrated not only a remarkable capacity for EG regeneration in vitro and in vivo but was also associated with improved animal survival, even when instituted 2 hours after induction of severe sepsis. In conclusion, 1) EG is disintegrated in sepsis, the event which contributes to high animal mortality; 2) pharmacologic acceleration of EG restoration can be achieved using SDX; and 3) SDX reduces vascular permeability, which is elevated in septic mice, and improves animal survival.