Project description:Angiocrine signaling by liver sinusoidal endothelial cells (LSEC) regulates liver functions such as liver growth, metabolic maturation, and regeneration. Recently, we identified GATA4 as the master regulator of LSEC specification during development. Here, we studied endothelial GATA4 in the adult liver and in hepatic disease pathogenesis. We generated adult Clec4g-icretg/0xGata4fl/fl (Gata4LSEC KO) mice with deficiency of Gata4 in LSEC. Livers were analyzed by histology, electron microscopy, immunohistochemistry/immunofluorescence, in-situ hybridization, and by expression profiling and ATAC-sequencing of isolated LSEC. For liver regeneration, partial hepatectomy was performed. As models of liver fibrosis, CDAA diet and chronic CCl4 exposure were applied. Human single cell RNAseq data sets were analyzed for endothelial alterations in healthy and cirrhotic livers. Genetic Gata4 deficiency in LSEC in adult mice caused perisinusoidal liver fibrosis, hepatopathy and impaired liver regeneration. Sinusoidal capillarization and LSEC-to-continuous endothelial transdifferentiation were accompanied by a profibrotic angiocrine switch including de novo endothelial expression of hepatic stellate cell-activating cytokine PDGFB. Increased chromatin accessibility and amplification by activated Myc mediated angiocrine PDGFB expression. In CDAA diet-induced perisinusoidal liver fibrosis, LSEC showed repression of GATA4, activation of MYC and the profibrotic angiocrine switch already detected in Gata4LSEC KO mice. Comparison of CDAA-fed Gata4LSEC KO and control mice demonstrated that endothelial Gata4 indeed protects from dietary-induced perisinusoidal liver fibrosis. In human cirrhotic livers, Gata4-positive LSEC and endothelial Gata4 target genes were reduced, while non-LSEC endothelial cells and Myc target genes including PDGFB were enriched. Endothelial GATA4 protects from perisinusoidal liver fibrosis by repressing MYC activation and profibrotic angiocrine signaling on the chromatin level. Therapies targeting the GATA4/MYC/PDGFB/PDGFRβ axis offer a promising strategy for the prevention and treatment of liver fibrosis.

Project description:Purpose: To clarify cellular and molecular mechanisms underlying impaired post-ischemic adaptive vascular responses and to evaluate reconstituted HDL (rHDL)-ApoA-I nanotherapy to rescue the defect in type 2 diabetic (T2DM) mouse model of hindlimb ischemia (HLI). Methods: Mice with beta-cell specific over-expression of insulin-like growth factor-2 in atherosclerotic background (IGF-II/ LDLR-/-ApoB100/100) with T2DM features were used in the study with C57BL/6J mice fed with a regular chow-diet (R36, Lactamin) serving as controls. Mice aged between 16 to 20 weeks were used in the study . Mice were anaesthetized with 1.5-2% isoflurane/air mixture during the surgical procedure. Hair was removed from the operation site and cleaned with sterile water. Single incision was made just above medial thigh and superficial femoral artery was separated from femoral vein and nerve. HLI was induced by unilateral ligation of femoral artery distal to the origin of the profunda femoral artery. The skin was closed with interrupted silk sutures. Mice were were administered with reconstituted ApoA-I nanoparticles with phosphatidyl serine core (rHDL) intravenously starting 2 days post-HLI with doses every 2 days until scarification with Saline injections serving as controls. Adductors muscle aortic endothelial cells (AECs) and Ischemic muscle Macrophages and Endothelial Cells (ECs) were isolated using a combination of magnetic assisted cell sorting and flow Cytometry using Macrophage (F4/80) and EC (CD-31) specific markers. Total RNA isolated from FACS sorted cells were used for RNA seq library preparation. Results: Cell-specific gene expression, flow cytometry and immunohistochemistry revealed a persistent Macrophage and Endothelial cell inflammation and a reduced anti-inflammatory M2-macrophage activation associated with impaired collateral remodelling and sprouting angiogenesis in T2DM mice. Furthermore, reconstituted HDL (rHDL)- ApoA-I was found to rescue impaired collateral remodelling and angiogenesis in T2DM mice through modulating EC and macrophage phenotypes. Conclusions: Our results suggest that an impaired collateral remodelling and sprouting angiogenesis in T2DM mice after HLI is associated with a persistent EC and macrophage inflammation and a reduced activation of anti-inflammatory M2-macrophage. Skewing the macrophage phenotype towards the pro-arteriogenic and pro-angiogenic anti-inflammatory M2-macrophages using reconstituted HDL (rHDL)-ApoA-I nanotherapy may serve as a potential therapeutic modality for T2DM PAD.

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Endothelial cells control muscle regeneration through angiocrine lactate

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