Endotoxin stimulates gene expression of ROS-eliminating pathways in rat hepatic endothelial and Kupffer cells

1996 ◽  
Vol 270 (4) ◽  
pp. G660-G666 ◽  
Author(s):  
Z. Spolarics

Reactive oxygen species (ROS) are mediators of cellular injury and play a putative role in the onset of hepatic damage during endotoxemia or sepsis. It has been suggested that induction of glucose-6-phosphate (G-6-P) dehydrogenase, the key enzyme of the hexose monophosphate shunt (HMS), may support ROS-producing or ROS-eliminating pathways in hepatic endothelial and Kupffer cells during endotoxemia. The aim of the study was to assess in vivo lipopolysaccharide (LPS)-induced alterations in rat gene expression of selected enzymes that are in functional relationship with the HMS. mRNA levels and activities of glucose transporter GLUT-1, Mn- and CuZn-dependent superoxide dismutases (Mn-SOD and CuZn-SOD), and Se-dependent glutathione peroxidase (Se-GPX) were determined. Cellular extracts were analyzed 7 or 22 h after injection of LPS (Escherichia coli, 2 mg/kg ip) or injection of saline. Exposure to LPS for 7 or 22 h caused a 10- to 25-fold increase in GLUT-1 mRNA levels in endothelial and Kupffer cells. In parenchymal cells, GLUT-1 mRNA expression was low, and LPS caused no marked changes. Cellular levels of Mn-SOD mRNA were 20-40 times greater in all hepatic cells from LPS-treated animals than in cells from control rats. LPS at 22 h increased Mn-SOD activity by 45% in endothelial cells but caused no significant changes in Kupffer or parenchymal cells. Message levels and enzyme activities of CuZn-SOD and Se-GPX were significantly elevated 22 h after LPS injection in endothelial cells only. Thus LPS results in marked upregulation of functionally related genes in hepatic cells. In endothelial cells, the simultaneous upregulation of GLUT-1, G-6-P dehydrogenase, Mn-SOD, CuZn-SOD, and Se-GPX may represent an important mechanism for accelerated elimination of ROS released from activated sinusoidal phagocytes. In Kupffer cells, upregulated GLUT-1 and G-6-P dehydrogenase, together with constitutively present SOD and lack of upregulated Se-GPX, suggest an elevated capacity to produce O2- and H2O2 that is consistent with primed bacterial killing.

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Franca Marino ◽  
Luigina Guasti ◽  
Matteo Tozzi ◽  
Laura Schembri ◽  
Luana Castiglioni ◽  
...  

Atherosclerosis is an inflammatory disease characterized by immunological activity, in which endothelial dysfunction represents an early event leading to subsequent inflammatory vascular damage. We investigated gene expression of the adhesion molecules (AMs) ICAM-1, VCAM-1, andβ1-integrin in endothelial cells (ECs) isolated from venous blood (circulating EC, cEC) and purified from femoral plaques (pEC) obtained from 9 patients with peripheral artery disease (PAD) submitted to femoral artery thrombendarterectomy (FEA). In addition, in peripheral blood mononuclear cells (PBMCs) of the same subjects, we investigated gene expression of IFN-γ, IL-4, TGF-β, and IL-10. Patients were longitudinally evaluated 1 month before surgery, when statin treatment was established, at the time of surgery, and after 2 and 5 months. All AM mRNA levels, measured by means of real-time PCR, in cEC diminished during the study, up to 41–50% of initial levels at followup. AM mRNA expression was significantly higher in pEC than in cEC. During the study, in PBMCs, TGF-βand IL-10 mRNA levels remained unchanged while IFN-γand IL-4 levels increased; however, the ratio IFN-γ/IL-4 showed no significant modification. In PAD patients, FEA and statin treatment induce a profound reduction of AM expression in cEC and affect cytokine mRNA expression in PBMCs.


1995 ◽  
Vol 269 (5) ◽  
pp. C1228-C1234 ◽  
Author(s):  
Y. Mitani ◽  
A. Behrooz ◽  
G. R. Dubyak ◽  
F. Ismail-Beigi

We tested the hypothesis that an increase in cytosolic calcium concentration stimulates glucose transporter isoform (GLUT-1) gene expression. Exposure of a rat liver cell line (Clone 9) to 3 microM A-23187 for 12 h resulted in 3-, 5-, and 10-fold increases in cytochalasin B-inhibitable 3-O-methyl-D-glucose transport, GLUT-1 protein, and GLUT-1 mRNA content, respectively. The induction of GLUT-1 mRNA in response to A-23187 is not preceded by a significant decrease in cell ATP content. This induction is prevented by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid in conjunction with ethylene glycol-bis(beta-aminoethyl ether)-N,N, N',N'-tetraacetic acid. To investigate the mechanism of GLUT-1 mRNA induction, we found that exposure to A-23187 stabilized GLUT-1 mRNA: with the employment of actinomycin D, GLUT-1 mRNA had a half-life of 1.5 and 5.5 h in control and A-23187-treated cells, respectively. In nuclear run-on assays, the rate of GLUT-1 gene transcription was stimulated 1.5- to 1.7-fold in nuclei isolated from cells exposed to A-23187 for either 30 min or 2 h. These results demonstrate that exposure to A-23187 stimulates GLUT-1 gene expression and that the increase in GLUT-1 mRNA content is mediated in part by enhanced GLUT-1 gene transcription as well as decreased GLUT-1 mRNA degradation. The increase in GLUT-1 mRNA content, in turn, is associated with increased cell GLUT-1 content and enhanced glucose transport.


1997 ◽  
Vol 321 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Belinda BREEDVELD ◽  
Kees SCHOONDERWOERD ◽  
Adrie J. M. VERHOEVEN ◽  
Rob WILLEMSEN ◽  
Hans JANSEN

Hepatic lipase (HL) is thought to be located at the vascular endothelium in the liver. However, it has also been implicated in the binding and internalization of chylomicron remnants in the parenchymal cells. In view of this apparent discrepancy between localization and function, we re-investigated the localization of HL in rat liver using biochemical and immunohistochemical techniques. The binding of HL to endothelial cells was studied in primary cultures of rat liver endothelial cells. Endothelial cells bound HL in a saturable manner with high affinity. However, the binding capacity accounted for at most 1% of the total HL activity present in the whole liver. These results contrasted with earlier studies, in which non-parenchymal cell (NPC) preparations had been found to bind HL with a high capacity. To study HL binding to the different components of the NPC preparations, we separated endothelial cells, Kupffer cells and blebs by counterflow elutriation. Kupffer cells and endothelial cells showed a relatively low HL-binding capacity. In contrast, the blebs, representing parenchymal-cell-derived material, had a high HL-binding capacity (33 m-units/mg of protein) and accounted for more than 80% of the total HL binding in the NPC preparation. In contrast with endothelial and Kupffer cells, the HL-binding capacity of parenchymal cells could account for almost all the HL activity found in the whole liver. These data strongly suggest that HL binding occurs at parenchymal liver cells. To confirm this conclusion in situ, we studied HL localization by immunocytochemical techniques. Using immunofluorescence, we confirmed the sinusoidal localization of HL. Immunoelectron microscopy demonstrated that virtually all HL was located at the microvilli of parenchymal liver cells, with a minor amount at the endothelium. We conclude that, in rat liver, HL is localized at the microvilli of parenchymal cells.


2006 ◽  
Vol 399 (1) ◽  
pp. 131-139 ◽  
Author(s):  
Seung-Soon Im ◽  
Sool-Ki Kwon ◽  
Seung-Youn Kang ◽  
Tae-Hyun Kim ◽  
Ha-Il Kim ◽  
...  

Expression of the GLUT4 (glucose transporter type 4 isoform) gene in adipocytes is subject to hormonal or metabolic control. In the present study, we have characterized an adipose tissue transcription factor that is influenced by fasting/refeeding regimens and insulin. Northern blotting showed that refeeding increased GLUT4 mRNA levels for 24 h in adipose tissue. Consistent with an increased GLUT4 gene expression, the mRNA levels of SREBP (sterol-regulatory-element-binding protein)-1c in adipose tissue were also increased by refeeding. In streptozotocin-induced diabetic rats, insulin treatment increased the mRNA levels of GLUT4 in adipose tissue. Serial deletion, luciferase reporter assays and electrophoretic mobility-shift assay studies indicated that the putative sterol response element is located in the region between bases −109 and −100 of the human GLUT4 promoter. Transduction of the SREBP-1c dominant negative form to differentiated 3T3-L1 adipocytes caused a reduction in the mRNA levels of GLUT4, suggesting that SREBP-1c mediates the transcription of GLUT4. In vivo chromatin immunoprecipitation revealed that refeeding increased the binding of SREBP-1 to the putative sterol-response element in the GLUT4. Furthermore, treating streptozotocin-induced diabetic rats with insulin restored SREBP-1 binding. In addition, we have identified an Sp1 binding site adjacent to the functional sterol-response element in the GLUT4 promoter. The Sp1 site appears to play an additive role in SREBP-1c mediated GLUT4 gene upregulation. These results suggest that upregulation of GLUT4 gene transcription might be directly mediated by SREBP-1c in adipose tissue.


1990 ◽  
Vol 268 (1) ◽  
pp. 225-230 ◽  
Author(s):  
A E Canfield ◽  
R P Boot-Handford ◽  
A M Schor

Endothelial cells plated on the surface of a two-dimensional substratum (gelatin-coated dishes, dishes coated with native type I collagen or collagen gels) form a cobblestone monolayer at confluence, whereas cells plated within a three-dimensional gel matrix elongate into a sprouting morphology and self-associate into tube-like structures. In this study, we have compared the synthesis of thrombospondin by quiescent endothelial cells displaying (a) the same morphological phenotype (cobblestone) on different substrata (gelatin and collagen) and (b) different morphological phenotypes (cobblestone and sprouting) on the same substratum (collagen). We demonstrate that thrombospondin is a major biosynthetic product of confluent, quiescent cells cultured on dishes coated with either gelatin or collagen, and that the synthesis of this protein is markedly decreased when cells are plated on or in three-dimensional collagen gels. Moreover, we demonstrate that cells plated in gel (sprouting) secrete less thrombospondin than do cells plated on the gel surface (cobblestone). The regulation of thrombospondin synthesis is reversible and occurs at the level of transcription, as steady-state mRNA levels for thrombospondin decrease in a manner comparable with the levels of protein secreted by these cells. We also show that mRNA levels for laminin B2 chains are increased when cells are cultured on and in collagen gels compared with on gelatin-coated dishes, suggesting that the syntheses of thrombospondin and laminin are regulated by different mechanisms. When cells are cultured on gelatin- or collagen-coated dishes, thrombospondin gene expression is directly proportional to the proliferative state of the cultures. By contrast, the synthesis of thrombospondin by cells cultured on collagen gels remains at equally low levels whether they are labelled when they are sparse and rapidly proliferating or when they are confluent and quiescent. Fibronectin synthesis was found to increase with increasing confluency of the cells plated on all three substrata. These results demonstrate that thrombospondin gene expression is modulated by cell shape, cell proliferation and the nature of the substratum used for cell culture.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3269-3269
Author(s):  
Jasmin Wellbrock ◽  
Sara Sheikhzadeh ◽  
Veronika Bonk ◽  
Leticia Oliveira-Ferrer ◽  
Kristin Klaetschke ◽  
...  

Abstract Abstract 3269 The Loeys-Dietz syndrome (LDS) is an inherited connective tissue disorder with symptoms similar to those of Marfan syndrome and the vascular type of Ehlers-Danlos syndrome. Most patients with LDS develop severe aortic aneurysms resulting in early need of surgical intervention. Patients with LDS harbour a mutation in the transforming growth factor β (TGF-β) receptors TGFBR1 (also named ALK-5) or TGFBR2. Since the TGF-β pathway plays a crucial role in many cellular processes including angiogenesis, we focussed our analyses on endothelial cell dysfunction in patients with Loeys-Dietz syndrome. We isolated circulating outgrowth endothelial cells (OEC) from the peripheral blood of two LDS patients (one female, 54 years; one male, 26 years old) both harbouring a mutation in the TGFBR2 gene. Gene expression profiles of OEC clones were performed using Affymetrix Human Genome U133 Plus 2.0 Arrays and confirmed by quantitative PCR analysis for genes of interest. OEC clones isolated from age- and sex-matched healthy controls served as reference subjects. We demonstrate that several genes belonging to the TGF-β pathway had altered expression in OECs isolated from LDS patients compared to those from healthy controls. For example, mRNA levels of bone morphogenic proteins (BMP) 2 and 4 were decreased in both LDS OEC clones (mean decrease 4 and 6 fold, respectively) whereas gene expression of inhibitory downstream molecule SMAD-6 was increased 2-fold. In both analysed OEC clones from LDS patients, gene expression of BMP antagonist Gremlin-1 (also known as Drm) showed the most prominent dysregulation with a 1136-fold and 164-fold higher expression in LDS OECs compared to healthy controls, respectively. Interestingly, in OECs isolated from healthy donors, Gremlin-1 expression was significantly down-regulated after incubation with SB431542 (5 μM), a small molecule inhibitor of the TGF-β receptor complex (mean decrease 4 fold; t-test: p = 0.002; n = 6). In contrast, the stimulation of OEC clones with TGF-β1 (1 ng/ml) resulted in significant up-regulation of Gremlin-1 mRNA levels (mean increase 7 fold; t-test: p = 0.014; n = 6). Apparently, the up-regulation of Gremlin-1 in LDS OECs seems to mirror an activated TGF-β signalling cascade in outgrowth endothelial cells. These findings are in line with other studies published on LDS where hyperactivity of the TGF-β downstream signalling was demonstrated by higher phosphorylation levels of SMAD-2 in the aortic media of LDS patients (Loeys et al., Nat Genet. 2005 Mar;37(3):275–81). Gremlin-1 might represent a second gene supporting the concept of increased TGF-β signalling in Loeys-Dietz syndrome. Gremlin-1 itself displays opposing effects on angiogenesis. First, it is known as a pro-angiogenic factor and was recently shown to stimulate angiogenesis via direct binding to the VEGF receptor 2 (Mitola et al., Blood. 2010 Nov 4;116(18):3677–80). On the other hand, as antagonist of bone morphogenic proteins, Gremlin-1 possesses anti-angiogenic properties by suppressing pro-angiogenic effects of BMP-2 and BMP-4. In summary, we believe that due to its drastic up-regulation in OECs of LDS patients, Gremlin-1 represents a crucial effector of dysregulated TGF-β signalling in endothelial cells inducing vascular pathology in Loeys-Dietz syndrome. Disclosures: Fiedler: Pfizer: Research Funding.


1992 ◽  
Vol 263 (3) ◽  
pp. E562-E569 ◽  
Author(s):  
W. I. Sivitz ◽  
D. D. Lund ◽  
B. Yorek ◽  
M. Grover-McKay ◽  
P. G. Schmid

To investigate the mechanism by which cardiac glucose utilization increases during hypoxia and increased work load, we studied the effect of 2 and 14 days of hypobaric hypoxia on the expression of two subtypes of the facilitative D-glucose transporter, the GLUT-4 or "insulin-regulatable" isoform and the GLUT-1 isoform thought to mediate basal transport. Rats lose weight when exposed to hypobaric hypoxia, so fasting controls were used in the 2-day studies and pair-fed controls in the 14-day experiments. Hypobaric hypoxia (PO2 69 mmHg) resulted in right ventricular (RV), but not left ventricular (LV), hypertrophy. RV and LV GLUT-1 mRNA levels increased 2- to 3-fold after 2 days and 1.5- to 2-fold after 14 days of hypobaric hypoxia compared with both fasted rats and normal controls. RV GLUT-1 protein increased approximately 3-fold and LV GLUT-1 protein increased 1.5-fold after 14 days of hypobaric hypoxia vs. both pair-fed and normal controls. RV GLUT-4 mRNA decreased to 26% and RV GLUT-4 protein decreased to 54% of normal control levels as a result of 2 days of hypobaric hypoxia. RV GLUT-4 mRNA decreased to 64% of normal control levels with no change in RV GLUT-4 protein as a result of 2 days of fasting. We conclude that hypobaric hypoxia increases cardiac GLUT-1 expression at the pretranslational level in both ventricles. The greater increase in GLUT-1 protein on the right suggests an additive effect of pressure overload. GLUT-4 expression is reduced early in the development of RV hypertrophy.


1990 ◽  
Vol 268 (3) ◽  
pp. 685-691 ◽  
Author(s):  
H F Bakkeren ◽  
F Kuipers ◽  
R J Vonk ◽  
T J C Van Berkel

Acetylated low-density lipoprotein (acetyl-LDL), biologically labelled in the cholesterol moiety of cholesteryl oleate, was injected into control and oestrogen-treated rats. The serum clearance, the distribution among the various lipoproteins, the hepatic localization and the biliary secretion of the [3H]cholesterol moiety were determined at various times after injection. In order to monitor the intrahepatic metabolism of the cholesterol esters of acetyl-LDL in vivo, the liver was subdivided into parenchymal, endothelial and Kupffer cells by a low-temperature cell-isolation procedure. In both control and oestrogen-treated rats, acetyl-LDL is rapidly cleared from the circulation, mainly by the liver endothelial cells. Subsequently, the cholesterol esters are hydrolysed, and within 1 h after injection, about 60% of the cell- associated cholesterol is released. The [3H]cholesterol is mainly recovered in the high-density lipoprotein (HDL) range of the serum of control rats, while low levels of radioactivity are detected in serum of oestrogen-treated rats. In control rats cholesterol is transported from endothelial cells to parenchymal cells (reverse cholesterol transport), where it is converted into bile acids and secreted into bile. The data thus provide evidence that HDL can serve as acceptors for cholesterol from endothelial cells in vivo, whereby efficient delivery to the parenchymal cells and bile is assured. In oestrogen-treated rats the radioactivity from the endothelial cells is released with similar kinetics as in control rats. However, only a small percentage of radioactivity is found in the HDL fraction and an increased uptake of radioactivity in Kupffer cells is observed. The secretion of radioactivity into bile is greatly delayed in oestrogen-treated rats. It is concluded that, in the absence of extracellular lipoproteins, endothelial cells can still release cholesterol, although for efficient transport to liver parenchymal cells and bile, HDL is indispensable.


2022 ◽  
Vol 19 (1) ◽  
Author(s):  
Burak Ozgür ◽  
Hans Christian Cederberg Helms ◽  
Erica Tornabene ◽  
Birger Brodin

Abstract Background Brain capillary endothelial cells (BCECs) experience hypoxic conditions during early brain development. The newly formed capillaries are tight and functional before astrocytes and pericytes join the capillaries and establish the neurovascular unit. Brain endothelial cell phenotype markers P-gp (ABCB1), LAT-1(SLC7A5), GLUT-1(SLC2A1), and TFR(TFRC) have all been described to be hypoxia sensitive. Therefore, we hypothesized that monolayers of BCECs, cultured under hypoxic conditions, would show an increase in LAT-1, GLUT-1 and TFR expression and display tight endothelial barriers. Methods and results Primary bovine BCECs were cultured under normoxic and hypoxic conditions. Chronic hypoxia induced HIF-1α stabilization and translocation to the nucleus, as judged by immunocytochemistry and confocal laser scanning imaging. Endothelial cell morphology, claudin-5 and ZO-1 localization and barrier integrity were unaffected by hypoxia, indicating that the tight junctions in the BBB model were not compromised. SLC7A5, SLC2A1, and TFRC-mRNA levels were increased in hypoxic cultures, while ABCB1 remained unchanged as shown by real-time qPCR. P-gp, TfR and GLUT-1 were found to be significantly increased at protein levels. An increase in uptake of [3H]-glucose was demonstrated, while a non-significant increase in the efflux ratio of the P-gp substrate [3H]-digoxin was observed in hypoxic cells. No changes were observed in functional LAT-1 as judged by uptake studies of [3H]-leucine. Stabilization of HIF-1α under normoxic conditions with desferrioxamine (DFO) mimicked the effects of hypoxia on endothelial cells. Furthermore, low concentrations of DFO caused an increase in transendothelial electrical resistance (TEER), suggesting that a slight activation of the HIF-1α system may actually increase brain endothelial monolayer tightness. Moreover, exposure of confluent monolayers to hypoxia resulted in markedly increase in TEER after 24 and 48 h, which corresponded to a higher transcript level of CLDN5. Conclusions Our findings collectively suggest that hypoxic conditions increase some BBB transporters' expression via HIF-1α stabilization, without compromising monolayer integrity. This may in part explain why brain capillaries show early maturation, in terms of barrier tightness and protein expression, during embryogenesis, and provides a novel methodological tool for optimal brain endothelial culture.


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