Plasminogen Activator Inhibitor-1 Expression in Human Liver and Healthy or Atherosclerotic Vessel Walls

1994 ◽  
Vol 72 (01) ◽  
pp. 044-053 ◽  
Author(s):  
N Chomiki ◽  
M Henry ◽  
M C Alessi ◽  
F Anfosso ◽  
I Juhan-Vague
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Plasminogen Activator ◽  
Human Liver ◽  
Plasminogen Activator Inhibitor ◽  
Muscle Cells ◽  
Vessel Walls ◽  
Activator Inhibitor ◽  
Pai 1

SummaryIndividuals with elevated levels of plasminogen activator inhibitor type 1 are at risk of developing atherosclerosis. The mechanisms leading to increased plasma PAI-1 concentrations are not well understood. The link observed between increased PAI-1 levels and insulin resistance has lead workers to investigate the effects of insulin or triglyceride rich lipoproteins on PAI-1 production by cultured hepatocytes or endothelial cells. However, little is known about the contribution of these cells to PAI-1 production in vivo. We have studied the expression of PAI-1 in human liver sections as well as in vessel walls from different territories, by immunocytochemistry and in situ hybridization.We have observed that normal liver endothelial cells expressed PAI-1 while parenchymal cells did not. However, this fact does not refute the role of parenchymal liver cells in pathological states.In healthy vessels, PAI-1 mRNA and protein were detected primarily at the endothelium from the lumen as well as from the vasa vasorum. In normal arteries, smooth muscle cells were able to produce PAI-1 depending on the territory tested. In deeply altered vessels, PAI-1 expression was observed in neovessels scattering the lesions, in some intimal cells and in smooth muscle cells. Local increase PAI-1 mRNA described in atherosclerotic lesions could be due to the abundant neovascularization present in the lesion as well as a raised expression in smooth muscle cells. The increased PAI-1 in atherosclerosis could lead to fibrin deposit during plaque rupture contributing further to the development and progression of the lesion.

scholarly journals Human fibroblasts downregulate plasminogen activator inhibitor type-1 in cultured human macrovascular and microvascular endothelial cells

Blood ◽  
1996 ◽  
Vol 88 (10) ◽  
pp. 3880-3886 ◽  
Author(s):  
JC Zhang ◽  
A Fabry ◽  
L Paucz ◽  
J Wojta ◽  
BR Binder
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Inhibitor Type ◽  
Activator Inhibitor Type ◽  
Activator Inhibitor ◽  
Pai 1

We have previously reported that plasminogen activator inhibitor type-1 (PAI-1) expression in endothelial cells (ECs) can be modulated differently by smooth muscle cells depending on their origin. Human pulmonary artery smooth muscle cells (HPASMCs) strongly downregulated PAI-1 expression in ECs. Fibroblasts (FBs) are another cell type that could come in close contact with ECs. Therefore, it was the aim of this study to investigate whether FBs could also influence the fibrinolytic potential of ECs. As in the case of HPASMCs, PAI-1 antigen produced by human umbilical vein ECs (HUVECs) cocultured with human skin FBs (HSFBs) was significantly lower as compared with the sum of PAI-1 secreted by the respective cell types cultured separately. Not only HUVECs but also human skin microvascular ECs (HSMECs) responded in a dose-dependent way to serum-free conditioned media (CM) from HSFBs from one individual donor. Similar results were obtained when CM from HSFBs from four other individual donors were used. PAI-1 mRNA decreased in HUVECs incubated for 6 hours with HSFB-CM to 24% to 55% of control, depending on the preparation of HSFBs used. A significant PAI-1 downregulatory effect was only observed when CM from low-passage HSFBs (up to passage no. 5) was used, whereas no reduction in EC PAI-1 production was observed with CM obtained from HSFBs in passage no. 8. This PAI-1 downregulatory activity present in HSFB-CM was heat-labile and had a molecular mass of approximately 5 kD. When CM from HPASMCs was analyzed in the same way, an almost identical elution profile was found. In conclusion, our data showed that FBs can decrease the expression of PAI-1 in ECs. Such an effect could be operative during wound-healing and at other capillary sites where FBs could render ECs profibrinolytic, thereby facilitating processes requiring an increase in proteolytic activity such as EC migration and proliferation.

LRP and αvβ3 mediate tPA activation of smooth muscle cells

2006 ◽  
Vol 291 (3) ◽  
pp. H1351-H1359 ◽  
Author(s):  
Sa'ed Akkawi ◽  
Taher Nassar ◽  
Mark Tarshis ◽  
Douglas B. Cines ◽  
Abd Al-Roof Higazi
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Plasminogen Activator ◽  
Vascular Smooth Muscle Cells ◽  
Density Lipoprotein ◽  
Plasminogen Activator Inhibitor ◽  
Muscle Cells ◽  
Tissue Type ◽  
Pai 1

Tissue-type plasminogen activator (tPA) regulates vascular contractility through the low-density lipoprotein-related receptor (LRP), and this effect is inhibited by plasminogen activator inhibitor type 1 (PAI-1). We now report that tPA-mediated vasocontraction also requires the integrin αvβ3. tPA-induced contraction of rat aortic rings is inhibited by the Arg-Gly-Asp (RGD) peptide and by monoclonal anti-αvβ3 antibody. tPA induces the formation of a complex between LRP and αvβ3 in vascular smooth muscle cells. The three proteins are internalized within 10 min, causing the cells to become refractory to the readdition of tPA. LRP and αvβ3 return to the cell surface by 90 min, restoring cell responsiveness to tPA. PAI-1 and the PAI-1-derived hexapeptide EEIIMD abolish the vasocontractile activity of tPA and inhibit the tPA-mediated interaction between LRP and αvβ3. tPA induces calcium mobilization from intracellular stores in vascular smooth muscle cells, and this effect is inhibited by PAI-1, RGD, and antibodies to both LRP and αvβ3. These data indicate that tPA-mediated vasocontraction involves the coordinated interaction of LRP with αvβ3. Delineating the mechanism underlying these interactions and the nature of the signals transduced may provide new tools to regulate vascular tone and other consequences of tPA-mediated signaling.

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