Endothelin-1 production by hepatic endothelial cells: characterization and augmentation by endotoxin exposure

Activation of endothelin (ET) receptors in the liver causes vasoconstriction, glucose production, and lipid and peptide mediator synthesis. In the intact rat, a bolus infusion of endotoxin into a mesenteric vein served as an acute exposure model of endotoxemia. In response to this challenge, a ninefold increase in hepatic ET-1 mRNA occurred within 3 h. The plasma level of immunoreactive ET-1 (irET-1) increased correspondingly by 8.5-fold within 6 h. ET-1 mRNA levels in liver endothelial cells (EC) isolated from livers of endotoxin-treated rats at various times after endotoxin challenge showed a more gradual increase. Northern blot analyses of the major liver cell types demonstrated that ET-1 mRNA was most abundant in the EC. The present results document a significant increase in the circulating level of irET-1 during episodes of endotoxemia. The increased hepatic ET-1 production in response to endotoxin infusion suggests that ET-1 produced in the liver could make a significant contribution to the plasma irET-1 and may be an important component in the hepatic responses to systemic trauma.

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Regulation of endothelin synthesis in hepatic endothelial cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.274.6.g1068 ◽

1998 ◽

Vol 274 (6) ◽

pp. G1068-G1076 ◽

Cited By ~ 4

Author(s):

Ann T. Eakes ◽

Merle S. Olson

Keyword(s):

Endothelial Cells ◽

Mrna Expression ◽

Kupffer Cells ◽

Transforming Growth Factor ◽

Culture Media ◽

Mrna Level ◽

Endotoxin Challenge ◽

Endotoxin Exposure ◽

Tnf Α ◽

Liver Endothelial Cells

Endothelin (ET) stimulates vasoconstriction and glucose production and mediator synthesis in the liver. Only hepatic endothelial cells express ET-1 mRNA, and during endotoxemia in the intact rat, a ninefold increase in hepatic ET-1 mRNA occurs within 3 h of lipopolysaccharide (LPS) infusion [A. T. Eakes, K. M. Howard, J. E. Miller, and M. S. Olson. Am. J. Physiol. 272 ( Gastrointest. Liver Physiol. 35): G605–G611, 1997]. The present study defines the mechanism by which hepatic ET production is enhanced during endotoxin exposure. Culture media conditioned by exposure to endotoxin-treated Kupffer cells stimulated a twofold increase in immunoreactive ET-1 (irET-1) secretion by liver endothelial cells. Transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), LPS, and platelet-activating factor (PAF) were tested for their ability to stimulate cultured liver endothelial cells to secrete irET-1. Although TNF-α, LPS, and PAF had no significant effect on ET-1 synthesis, TGF-β increased ET-1 mRNA expression and irET-1 secretion. In coculture experiments, treating Kupffer cells with endotoxin caused a doubling of the ET-1 mRNA level in the liver endothelial cells. This increase in ET-1 mRNA was attenuated by a TGF-β-neutralizing antibody. Hence, a paracrine signaling mechanism operates between Kupffer cells that release TGF-β on endotoxin challenge and hepatic endothelial cells in which TGF-β stimulates ET-1 mRNA expression and ET-1 secretion; this intercellular signaling relationship is an important component in the hepatic responses to endotoxin exposure.

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Osmotic regulation of Na-myo-inositol cotransporter mRNA level and activity in endothelial and neural cells

AJP Cell Physiology ◽

10.1152/ajpcell.1996.270.4.c990 ◽

1996 ◽

Vol 270 (4) ◽

pp. C990-C997 ◽

Cited By ~ 55

Author(s):

T. J. Wiese ◽

J. A. Dunlap ◽

C. E. Conner ◽

J. A. Grzybowski ◽

W. L. Lowe ◽

...

Keyword(s):

Endothelial Cells ◽

Mrna Level ◽

Cell Types ◽

Neural Cells ◽

Maximal Velocity ◽

Mrna Levels ◽

Osmotic Regulation ◽

High Affinity ◽

Sodium Dependent ◽

Renal Origin

Myo-inositol (MI) is an important factor in the synthesis of phosphoinositides, and as an osmolyte, MI contributes to the regulation of cell volume. In cells of renal origin, hypertonicity causes an increase in sodium-dependent MI transporter (SMIT) mRNA levels and MI transport. However, it is unknown whether changes in osmolarity regulate transport of MI in neural or endxsothelial cells. IN these studies, neural and endothelial cells were exposed to hyperosmotic medium for up to 48 h, and the effect on MI transport was determined. Transport of MI was maximally increased by exposing the cells to hyperosmotic medium for 24 h. Kinetic analysis of high-affinity MI transport demonstrated an increase in the apparent maximal velocity with no significant change in the apparent Km. The hyperosmotic induction of MI transport was blocked by the addition of cycloheximide, indicating a requirement for protein synthesis, and was associated with increased levels of SMIT mRNA. In contrast to the effect of hypertonicity, exposure of neural and endothelial cells to hypotonic conditions caused a decrease in SMIT mRNA levels and MI transport in endothelial cells. These studies demonstrate that, in extrarenal cell types, changes in osmolarity also regulate SMIT activity and mRNA levels.

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Modulation of insulin-like growth factor (IGF) and IGF binding protein biosynthesis by hypoxia in cultured vascular endothelial cells

Journal of Endocrinology ◽

10.1677/joe.0.1570013 ◽

1998 ◽

Vol 157 (1) ◽

pp. 13-24 ◽

Cited By ~ 37

Author(s):

M Tucci ◽

K Nygard ◽

BV Tanswell ◽

HW Farber ◽

DJ Hill ◽

...

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Binding Protein ◽

Protein Biosynthesis ◽

Cell Types ◽

Mrna Levels ◽

Insulin Like Growth Factor ◽

Igf Binding ◽

Igf Binding Protein ◽

Igfbp 3

Endothelial cells (EC) are hypoxia-tolerant and their capacity to proliferate in low oxygen tension is essential to maintain vascular endothelium integrity. The present study addresses whether hypoxia alters the expression of insulin-like growth factor (IGF) and IGF binding protein (IGFBP) genes in bovine aortic EC (BAEC) and bovine pulmonary artery EC (BPAEC). EC were cultured in normoxic (21%) conditions and exposed to 0% oxygen for 24, 48, or 72 h; some cells were reoxygenated by exposure to 21% oxygen for 24 or 48 h following hypoxia. IGF-I peptide and mRNA levels were very low in both cell types, and decreased further with exposure to hypoxia. Ligand blotting showed that both cell types synthesized 24 kDa (IGFBP-4), 30 kDa (IGFBP-5 and/or IGFBP-6), 43 kDa and 48 kDa IGFBPs (IGFBP-3 glycosylation variants). IGFBP-4 was the predominant IGFBP expressed by both cell types and did not change with exposure to hypoxia. Hypoxia caused a significant increase in IGFBP-3 secretion in BPAEC but not in BAEC. IGFBP-3 stable mRNA levels in BPAEC were increased correspondingly. IGFBP-5 was expressed only in BAEC and decreased with exposure to hypoxia. IGFBP-6 mRNA expression was low and increased in both cell types with exposure to hypoxia. These results demonstrate that EC IGFBP baseline expression as well as its expression in hypoxia vary in different vascular beds and suggest that the IGFBPs may be the dominant paracrine regulators of proliferation of EC as well as maintenance of endothelium integrity during hypoxia.

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Downregulation of Endothelial Plexin A4 Under Inflammatory Conditions Impairs Vascular Integrity

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.633609 ◽

2021 ◽

Vol 8 ◽

Author(s):

Dianne Vreeken ◽

Caroline Suzanne Bruikman ◽

Wendy Stam ◽

Stefan Martinus Leonardus Cox ◽

Zsófia Nagy ◽

...

Keyword(s):

Endothelial Cells ◽

Barrier Function ◽

Network Formation ◽

Cell Types ◽

Vascular Leakage ◽

Cell Junctions ◽

Mrna Levels ◽

Human Monocytes ◽

Vascular Integrity ◽

Inflammatory Conditions

Objective: Besides hyperlipidemia, inflammation is an important determinant in the initiation and the progression of atherosclerosis. As Neuroimmune Guidance Cues (NGCs) are emerging as regulators of atherosclerosis, we set out to investigate the expression and function of inflammation-regulated NGCs.Methods and results: NGC expression in human monocytes and endothelial cells was assessed using a publicly available RNA dataset. Next, the mRNA levels of expressed NGCs were analyzed in primary human monocytes and endothelial cells after stimulation with IL1β or TNFα. Upon stimulation a total of 14 and 19 NGCs in monocytes and endothelial cells, respectively, were differentially expressed. Since plexin A4 (PLXNA4) was strongly downregulated in endothelial cells under inflammatory conditions, the role of PLXNA4 in endothelial function was investigated. Knockdown of PLXNA4 in endothelial cells markedly impaired the integrity of the monolayer leading to more elongated cells with an inflammatory phenotype. In addition, these cells showed an increase in actin stress fibers and decreased cell-cell junctions. Functional assays revealed decreased barrier function and capillary network formation of the endothelial cells, while vascular leakage and trans-endothelial migration of monocytes was increased.Conclusion: The current study demonstrates that pro-inflammatory conditions result in differential expression of NGCs in endothelial cells and monocytes, both culprit cell types in atherosclerosis. Specifically, endothelial PLXNA4 is reduced upon inflammation, while PLXNA4 maintains endothelial barrier function thereby preventing vascular leakage of fluids as well as cells. Taken together, PLXNA4 may well have a causal role in atherogenesis that deserves further investigation.

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Nitric oxide increases toxicity of hydrogen peroxide against rat liver endothelial cells and hepatocytes by inhibition of hydrogen peroxide degradation

AJP Cell Physiology ◽

10.1152/ajpcell.00366.2006 ◽

2007 ◽

Vol 292 (4) ◽

pp. C1440-C1449 ◽

Cited By ~ 22

Author(s):

Ursula Rauen ◽

Tongju Li ◽

Iosif Ioannidis ◽

Herbert de Groot

Keyword(s):

Nitric Oxide ◽

Hydrogen Peroxide ◽

Endothelial Cells ◽

Glutathione Peroxidase ◽

Cell Injury ◽

Early Time ◽

Cell Types ◽

Cytotoxic Action ◽

No Donor ◽

Liver Endothelial Cells

Nitric oxide (NO) and hydrogen peroxide (H2O2) show cooperativity in their cytotoxic action. The present study was performed to decipher the mechanisms underlying this phenomenon. In cultured liver endothelial cells and in cultured, glutathione-depleted hepatocytes, the combined exposure to NO (released by spermine NONOate, 1 mM) and H2O2 (released by glucose oxidase) induced cell injury that was far higher than the injury elicited by NO or H2O2 alone. In both cell types, the addition of the NO donor increased H2O2 steady-state levels, although with different kinetics: in hepatocytes, the increase in H2O2 levels was already evident at early time points while in liver endothelial cells it became evident after ≥2 h of incubation. NO exposure inhibited H2O2 degradation, assessed after addition of 50 μM, 200 μM, or 4 mM authentic H2O2, significantly in both cell types. However, again, early and delayed inhibition was observed. The late inhibition of H2O2 degradation in endothelial cells was paralleled by a decrease in glutathione peroxidase activity. Glutathione peroxidase inactivation was prevented by hypoxia or by ascorbate, suggesting inactivation by reactive nitrogen oxide species (NOx). Early inhibition of H2O2 degradation by NO, in contrast, could be mimicked by the catalase inhibitor azide. Together, these results suggest that the cooperative effect of NO and H2O2 is due to inhibition of H2O2 degradation by NO, namely to inhibition of catalase by NO itself (predominant in hepatocytes) and/or to inhibition of glutathione peroxidase by NOx (prevailing in endothelial cells).

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Identification of Multi-Omics Cell Signatures of Early Liver Injury

10.21203/rs.3.rs-701471/v1 ◽

2021 ◽

Author(s):

Maciej Migdał ◽

Eugeniusz Tralle ◽

Karim Abu Nahia ◽

Łukasz Bugajski ◽

Katarzyna Zofia Kędzierska ◽

...

Keyword(s):

Endothelial Cells ◽

Liver Injury ◽

Hepatic Stellate Cells ◽

Tissue Injury ◽

Early Stage ◽

Stellate Cells ◽

Cell Types ◽

Cell Type ◽

Cell Type Specific ◽

Liver Endothelial Cells

Abstract Background Liver fibrosis is a wound-healing response to tissue injury and inflammation hallmarked by the extracellular matrix (ECM) protein deposition in the liver parenchyma and tissue remodelling. Different cell types of the liver are known to play distinct roles in liver injury response. Hepatocytes and liver endothelial cells receive molecular signals indicating tissue injury and activate hepatic stellate cells which produce ECM proteins upon their activation. Despite the growing knowledge on the molecular mechanism underlying hepatic fibrosis in general, the cell-type-specific gene regulatory network associated with the initial response to hepatotoxic injury is still poorly characterized. Results In this study, we used thioacetamide (TAA) to induce hepatic injury in adult zebrafish. We isolated three major liver cell types - hepatocytes, endothelial cells and hepatic stellate cells - and identified cell-type-specific chromatin accessibility and transcriptional changes in an early stage of liver injury. We found that TAA induced transcriptional shifts in all three cell types hallmarked by significant alterations in the expression of genes related to fatty acid and carbohydrate metabolism, as well as immune response-associated and vascular-specific genes. Interestingly, liver endothelial cells exhibit the most pronounced response to liver injury at the transcriptome and chromatin level, hallmarked by the loss of their angiogenic phenotype. Conclusion Our results uncovered cell-type-specific transcriptome and epigenome responses to early stage liver injury, which provide valuable insights into understanding the molecular mechanism implicated in the early response of the liver to pro-fibrotic signals.

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Multi-omics analyses of early liver injury reveals cell-type-specific transcriptional and epigenomic shift

BMC Genomics ◽

10.1186/s12864-021-08173-1 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Maciej Migdał ◽

Eugeniusz Tralle ◽

Karim Abu Nahia ◽

Łukasz Bugajski ◽

Katarzyna Zofia Kędzierska ◽

...

Keyword(s):

Endothelial Cells ◽

Liver Injury ◽

Hepatic Stellate Cells ◽

Tissue Injury ◽

Early Stage ◽

Stellate Cells ◽

Cell Types ◽

Cell Type ◽

Cell Type Specific ◽

Liver Endothelial Cells

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VEGF is required for growth and survival in neonatal mice

Development ◽

10.1242/dev.126.6.1149 ◽

1999 ◽

Vol 126 (6) ◽

pp. 1149-1159 ◽

Cited By ~ 12

Author(s):

H.P. Gerber ◽

K.J. Hillan ◽

A.M. Ryan ◽

J. Kowalski ◽

G.A. Keller ◽

...

Keyword(s):

Endothelial Cells ◽

Gene Targeting ◽

Chimeric Protein ◽

Cell Types ◽

Postnatal Life ◽

Vegf Receptor ◽

Newborn Mice ◽

Growth And Survival ◽

Liver Endothelial Cells ◽

Inducible Gene

We employed two independent approaches to inactivate the angiogenic protein VEGF in newborn mice: inducible, Cre-loxP- mediated gene targeting, or administration of mFlt(1–3)-IgG, a soluble VEGF receptor chimeric protein. Partial inhibition of VEGF achieved by inducible gene targeting resulted in increased mortality, stunted body growth and impaired organ development, most notably of the liver. Administration of mFlt(1–3)-IgG, which achieves a higher degree of VEGF inhibition, resulted in nearly complete growth arrest and lethality. Ultrastructural analysis documented alterations in endothelial and other cell types. Histological and biochemical changes consistent with liver and renal failure were observed. Endothelial cells isolated from the liver of mFlt(1–3)-IgG-treated neonates demonstrated an increased apoptotic index, indicating that VEGF is required not only for proliferation but also for survival of endothelial cells. However, such treatment resulted in less significant alterations as the animal matured, and the dependence on VEGF was eventually lost some time after the fourth postnatal week. Administration of mFlt(1–3)-IgG to juvenile mice failed to induce apoptosis in liver endothelial cells. Thus, VEGF is essential for growth and survival in early postnatal life. However, in the fully developed animal, VEGF is likely to be involved primarily in active angiogenesis processes such as corpus luteum development.

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THE VESSEL WALL AS A SOURCE OF VASORHGOLATORY AND IMMDNOSTIMOLATORY CYTOKINES

10.1055/s-0038-1643982 ◽

1987 ◽

Author(s):

Peter Libby ◽

Stephen J C Warner ◽

Louis K Birinyi

Keyword(s):

Molecular Weight ◽

Endothelial Cells ◽

Vessel Wall ◽

Cell Types ◽

Mrna Levels ◽

Blood Vessel Wall ◽

Human Monocytes ◽

Blood Monocytes ◽

Mrna Accumulation ◽

Vascular Cell

The cytokines Interleukin-1 (IL-1) and Tumor Necrosis Factor (TNF, also known as cachectin) exhibit multiple effects on circulating blood cells and cells of the blood vessel wall. For example, these mediators elicit a coordinated Drogram of functions of endothelial cells (EC) that promotes blood coagulation and thrombosis, and lead to clot stabilization. Furthermore, IL-1 and TNF promote adherence to vascular endothelium of leukocytes of many classes.Thus, these cytokines are likely to be involved in signaling the pathologic changes in blood vessels that characterize a number of inflammatory or infectious processes. These two cytokines were originally isolated frcm activated human mononuclear phagocytes, hence their comnon designation as monokines and the terminology "interleukin". However, recent findings have broadened this concept considerably. It is now clear that many cell types can produce IL-1-1ike activity.Several groups showed that human vascular EC can secrete material that stimulates proliferation of thymocytes incubated with suboptima1 doses of the mitogenic lectin phytohemagglutinin, a typical acitivty of IL-1 (thymocyte costimulation).Two related but distinct genes cloned frcm human peripheral blood monocytes encode IL-1 molecules. In human blood monocytes stimulated with bacterial lioopolysaccharide (LPS) IL-1 beta (pi ∼ 7) is the major form expressed while IL-1 alpha (pi ∼ 5) is the less abundant species secreted by human monocytes under these conditions. We found that EC and smooth muscle cells (SMC) isolated from adult human vessels can express these same IL-1 genes. LPS, a standard stimulus to IL-1 secretion in the monocyte, caused accumulation of IL-1 beta mRNA in both vascular cell types. Endothelial cells frcm adult human vessels also contained IL-1 alpha mRNA when treated with LPS in the presence of cycloheximide and LPS-stimulated smooth muscle cells contained RNA that hybridized with an IL-1 alpha cDNA probe as well. Although both vascular cell types can transcribe these IL-1 genes, the time course of this response differs. LPS induced IL-1 beta mRNA production by SMC maximally at 4-6 hr., whereas maximal IL-1 induction by LPS in EC occured 1 day after initiation of the exposure. Actinanycin D (1 ug/ml) blocked 3H-uridine incorporation into macromolecules by > 95% in both EC & SMC, and prevented the LPS-induced increases in IL-1 mRNA levels in these cells. This result suggests that this potentially injurious stimulus causes IL-1 mRNA accumulation by an increase in rates of transcription. These LPS-induced increases in IL-1 mRNA levels corresponded to production of biologically active IL-1 determined as thymocyte costimulation activity. Interestingly, gel filtration experiments revealed a molecular weight of around 22kD for both SMC and EC-derived IL-1 secreted into culture medium in response to LPS. This molecular weight contrasts with the 17 kD species which is the fully processed product secreted frcm activated human monocytes. A possible explanation for this disparity is that the vascular cells secrete a partially processed intermediate form of mature IL-1. Other stimuli for IL-1 mRNA accumulation and secretion of biological activity include TNF and IL-1 itself. Recombinant human INF (≥ 10 ng/ml) increased IL-1 beta mRNA levels in EC & SMC, and caused the EC & SMC to release IL-1-1 ike thymocyte costimulation activity. Of interest is the recent observation that IL-1 itself can stimulate expression of IL-rl genes in vascular wall cells. Both IL-1 aloha and beta can increase IL-1 beta mRNA content in EC & SMC. Hris observation was confirmed with homogenous IL-1 prepared by recombinant DNA technologies (rIL-1). These findings raise the possibility of a novel positive feedback loop in vascular pathophysiology. We also found that rIL-1 alpha or beta also induced the production of prostaglandin E2 (PGE2) by both vascular SMC & EC. This prostanoid, induced by IL-1, inhibits thymocyte _ proliferation. Thus, IL-1 not only induced its own expression but increased production of this immunosuppressive prostanoid. This mechanism provides a potential negative control loop in regulation of the local immune response in blood vessels. Vie conclude that these cells of the blood vessel wall are a source of the potent vasoregulatory and immune mediators IL-1 alpha and beta. Since IL-1 influences the thrombotic, hemostatic, and fibrinolytic functions of endothelium, as well as other responses to acute injury, our findings suggest novel local control mechanisms that may be important in a variety of pathologic states.

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Regulation of bFGF expression and ANG II secretion in cardiac myocytes and microvascular endothelial cells

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1997.272.2.h958 ◽

1997 ◽

Vol 272 (2) ◽

pp. H958-H968 ◽

Cited By ~ 7

Author(s):

T. A. Fischer ◽

D. Ungureanu-Longrois ◽

K. Singh ◽

J. de Zengotita ◽

D. DeUgarte ◽

...

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Cardiac Muscle ◽

Cell Types ◽

Microvascular Endothelial Cells ◽

Mrna Levels ◽

Fibroblast Growth ◽

Ang Ii ◽

Cell Type ◽

A Cell

Basic fibroblast growth factor (bFGF; fibroblast growth factor-2) and angiotensin II (ANG II), among other peptide signaling autacoids (cytokines), are known to regulate the phenotypic adaptation of cardiac muscle to physiological stress. The cell type(s) in cardiac muscle responsible for ANG II synthesis and secretion and the role of endogenous cytokines in the regulation of bFGF induction remain unclear. With the use of confluent, serum-starved, low-passage cultures of cardiac microvascular endothelial cells (CMEC), ANG II could be detected in cellular lysates and in medium conditioned by these cells with the use of high-performance liquid chromatography followed by radioimmunoassay. The secretion of angiotensins by individual CMEC could be detected with a cell-blot assay technique. ANG II secretion was decreased by brefeldin A, an agent that interrupts constitutive and regulated secretory pathways for peptide autacoid/ hormone synthesis, suggesting de novo synthesis, activation, and secretion of angiotensins by CMEC. In primary isolates of adult rat ventricular myocytes (ARVM) and CMEC, ANG II, acting at ANG II type 1 receptors in both cell types, was found to increase bFGF mRNA levels measured by ribonuclease protection assay. Endothelin-1 (ET-1), which is known to be synthesized by CMEC, and bFGF itself, which has been detected in both ARVM and CMEC, increased bFGF transcript levels in both cell types. Interleukin-1beta (IL-1beta), which like ANG II and ET-1 is known to activate mitogen-activated protein kinases in both ARVM and CMEC, increased bFGF mRNA levels only in cardiac myocytes. Thus cytokines such as ANG II, ET-1, bFGF, and IL-1beta locally generated by cellular constituents of cardiac muscle, including CMEC, regulate bFGF mRNA levels in a cell type-specific manner.

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