Endothelial H2S-AMPK dysfunction upregulates the angiocrine factor PAI-1 and contributes to lung fibrosis
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ABSTRACT: Dysfunction of the vascular angiocrine system is critically involved in regenerative defects and fibrosis of injured organs. Previous studies have identified various angiocrine factors and found that risk factors such as aging and metabolic disorders can disturb the vascular angiocrine system in fibrotic organs. One existing key gap is what sense the fibrotic risk to modulate the vascular angiocrine system in organ fibrosis. Here, using human and mouse data, we discovered that the metabolic pathway hydrogen sulfide (H2S)-AMP-activated protein kinase (AMPK) is a sensor of fibrotic stress and serves as a key mechanism upregulating the angiocrine factor plasminogen activator inhibitor-1 (PAI-1) in endothelial cells to participate in lung fibrosis.
Project description:Microvascular endothelial cells (EC) display a high degree of phenotypic and functional heterogeneity among different organs. Organ-specific EC control their tissue microenvironment by angiocrine factors in health and disease. Liver sinusoidal EC (LSEC) are uniquely differentiated to fulfil important organ-specific functions in development, under homeostatic conditions, and in regeneration and liver pathology. Recently, Bmp2 has been identified by us as an organ-specific angiokine derived from LSEC. To study angiocrine Bmp2 signaling in the liver, we conditionally deleted Bmp2 in LSEC using EC subtype-specific Stab2-Cre mice. Genetic inactivation of hepatic angiocrine Bmp2 signaling in Stab2-Cre;Bmp2fl/fl (Bmp2LSECKO) mice caused massive iron overload in the liver, and increased serum iron levels and iron deposition in several organs similar to classic hereditary hemochromatosis. Iron overload was mediated by decreased hepatic expression of hepcidin, a key regulator of iron homeostasis. Thus, angiocrine Bmp2 signaling within the hepatic vascular niche represents a constitutive pathway indispensable for iron homeostasis in vivo that is non-redundant with Bmp6. Notably, we demonstrate that organ-specific angiocrine signaling is essential not only for the homeostasis of the respective organ, but also for the homeostasis of the whole organism.
Project description:Physiological memories of environmental stress can serve to predict future environmental changes, allowing the organism to initiate protective mechanisms and survive. Although physiological memories, or bookmarks, of environmental stress have been described in a wide range of organisms, from bacteria to plants to humans, the mechanism by which these memories persist in the absence of stress is still largely unknown. We have discovered that C. elegans transiently exposed to low doses of hydrogen sulfide (H2S) survive subsequent exposure to otherwise lethal H2S concentrations and induce H2S-responsive transcripts more robustly than naïve controls. H2S bookmarking can occur at any developmental stage and persists through cell divisions and development but is erased by fasting. We show that maintenance of the H2S bookmark requires the SET-2 histone methyltransferase and the CoREST-like demethylase complex. We propose a model in which exposure to low doses of H2S generates a long-lasting, epigenetic memory by modulating H3K4me2 modifications at specific promoters. Understanding the fundamental aspects of H2S bookmarking in this tractable system can provide mechanistic insight into how environmental exposures are translated into the epigenetic landscape in animals.
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: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:Hydrogen sulfide (H2S) is formed naturally from L-cysteine in a variety of mammalian and non-mammalian cells. To date, numerous biological effects have been ascribed to H2S including control of cardiovascular, immune and nervous function. Over or under production of H2S has been observed in several disease states including hypertension and inflammation. In addition, it has been stipulated that H2S may affect the ageing process. The model nematode Caenorhabditis elegans is ideally suited for assessing drug effects on lifespan since it is relatively short-lived, can be easily exposed to drugs and its genome is fully sequenced and widely annotated.
Project description:Hydrogen sulfide (H2S) is formed naturally from L-cysteine in a variety of mammalian and non-mammalian cells. To date, numerous biological effects have been ascribed to H2S including control of cardiovascular, immune and nervous function. Over or under production of H2S has been observed in several disease states including hypertension and inflammation. In addition, it has been stipulated that H2S may affect the ageing process. The model nematode Caenorhabditis elegans is ideally suited for assessing drug effects on lifespan since it is relatively short-lived, can be easily exposed to drugs and its genome is fully sequenced and widely annotated. The global transcriptome of control nematodes (raised using standardized laboratory conditions) was compared to nematodes exposed to 100 uM GYY4137 (morpholin-4-ium 4 methoxyphenyl(morpholino) phosphinodithioate), a slow releasing H2S donor drug.
Project description:Endothelial cells were transduced with different genes modulating signaling pathways and compared to GFP transduced control group to identify changes in the expression of the angiocrine factors. The experiment compared endothelial genetic changes upon Akt, MAP kinase and PymT activation.
Project description:Vascular inflammation and myofibroblast activation by TGF-β1 are key, yet-to-be-fully-understood pathological processes in fibrosis. Here we report the development of a novel human Tendon-on-a-Chip (hToC) to elucidate the role of TGF-β1 in peritendinous adhesions, a debilitating fibrosis condition affecting flexor tendon, which currently lacks biological therapies. The hToC allows the crosstalk between a vascular compartment harboring endothelial cells and monocytes with a tissue hydrogel compartment containing tendon fibroblasts and macrophages. We find that the hToC replicates in vivo inflammatory and fibrotic phenotypes in preclinical and clinical samples, including myofibroblast differentiation and tissue contraction, excessive ECM deposition, and inflammatory cytokines secretion. We further show the fibrotic phenotypes are driven by the interactions between the vascular and tissue compartments, mediating the transmigration of monocytes. We demonstrate significant overlap in fibrotic transcriptional signatures in the hToC with human tenolysis samples, including the mTOR pathway, a regulatory nexus of fibrosis across various organs. Treatment with Rapamycin suppressed the fibrotic phenotype on the hToC, which validates the hToC as a preclinical alternative for investigating fibrosis and testing therapeutics.
Project description:Liver sinusoidal endothelial cells (LSEC) represent a unique, organ-specific type of discontinuous endothelial cells. LSEC instruct the hepatic vascular niche by paracrine-acting angiocrine factors. Recently, we have shown that LSEC-specific transcriptional regulator GATA4 induces expression of BMP2 in cultured endothelial cells (EC) in vitro. Furthermore, angiocrine Bmp2 signaling in the liver in vivo was demonstrated to control iron homeostasis. Here, we investigated GATA4-dependent autocrine BMP2 signaling in endothelial cells by gene expression profiling. GATA4 induced a large cluster of inflammatory endothelial response genes in cultured EC, which is similar to previously identified virus-induced and interferon-associated responses. Treating the cells with the BMP2 inhibitor Noggin counter-regulated the GATA4-dependent inflammatory phenotype of EC, indicating that BMP2 is indeed the major driver. In contrast to continuous EC, LSEC were less prone to activation by BMP2. Notably, GATA4-dependent induction of the inflammatory EC response gene cluster was attenuated by over-expression of the LSEC-specific transcriptional modifier LMO3 while hepatocyte activation was fully preserved, indicating conserved BMP2 synthesis. In summary, our data suggest that transcriptional counter-regulation by GATA4 and LMO3 in LSEC prevents autocrine induction of an inflammatory phenotype, while maintaining angiocrine BMP2-mediated cell communication in the liver vascular niche.