Proteolytically Inactive Recombinant Forms of Urokinase Suppress Migration of Endothelial Cells

The uPA/uPAR System Orchestrates the Inflammatory Response, Vascular Homeostasis, and Immune System in Fibrosis Progression

Fibrotic diseases, such as systemic sclerosis (SSc), idiopathic pulmonary fibrosis, renal fibrosis and liver cirrhosis are characterized by tissue overgrowth due to excessive extracellular matrix (ECM) deposition. Fibrosis progression is caused by ECM overproduction and the inhibition of ECM degradation due to several events, including inflammation, vascular endothelial dysfunction, and immune abnormalities. Recently, it has been reported that urokinase plasminogen activator (uPA) and its receptor (uPAR), known to be fibrinolytic factors, orchestrate the inflammatory response, vascular homeostasis, and immune homeostasis system. The uPA/uPAR system may show promise as a potential therapeutic target for fibrotic diseases. This review considers the role of the uPA/uPAR system in the progression of fibrotic diseases.

Mesenchymal stromal cells enhance self-assembly of a HUVEC tubular network through uPA-uPAR/VEGFR2/integrin/NOTCH crosstalk

Endothelial cells (ECs) degrade the extracellular matrix of vessel walls and contact surrounding cells to facilitate migration during angiogenesis, leading to formation of an EC-tubular network (ETN). Mesenchymal stromal cells (MSC) support ETN formation when co-cultured with ECs, but the mechanism is incompletely understood. We examined the role of the urokinase-type plasminogen activator (uPA) system, i.e. the serine protease uPA, its inhibitor PAI-1, receptor uPAR/CD87, clearance by the low-density lipoprotein receptor-related protein (LRP1) and their molecular partners, in the formation of ETNs supported by adipose tissue-derived MSC. Co-culture of human umbilical vein ECs (HUVEC) with MSC increased mRNA expression levels of uPAR, MMP14, VEGFR2, TGFβ1, integrin β₃ and Notch pathway components (Notch1 receptor and ligands: Dll1, Dll4, Jag1) in HUVECs and uPA, uPAR, TGFβ1, integrin β₃, Jag1, Notch3 receptor in MSC. Inhibition at several steps in the activation process indicates that uPA, uPAR and LRP1 cross-talk with α_v-integrins, VEGFR2 and Notch receptors/ligands to mediate ETN formation in HUVEC-MSC co-culture. The urokinase system mediates ETN formation through the coordinated action of uPAR, uPA's catalytic activity, its binding to uPAR and its nuclear translocation. These studies identify potential targets to help control aberrant angiogenesis with minimal impact on healthy vasculature.

[Fibrinolytics: from the thrombolysis to the processes of blood vessels growth and remodeling, neurogenesis, carcinogenesis and fibrosis]

One of the most outstanding scientific achievements in the thrombolysis is the development and administration of fibrinolysin - the first Soviet drug that lyses blood clots. Intracoronary administration of fibrinolysin reduced the mortality of patients with myocardial infarction by almost 20%. For his work in this field Yevgeny Chazov was awarded the Lenin Prize in 1982. Over the next decades, under his leadership, the Cardiology Center established scientific and clinical laboratories that created new generations of drugs based on fibrinolytics for treating patients with myocardial infarction, restoration of blood flow in ischemic tissue, and also studying the mechanisms of remodeling of blood vessels involving the fibrinolysis system. It have been found new mechanisms of regulation of the navigation of blood vessels and nerves growth, tumor growth and its metastasis with the participation of the fibrinolysis system proteins. The review reports the role of the fibrinolysis system in the thrombolysis, blood vessels growth and remodeling, neurogenesis, carcinogenesis and fibrosis. The article is dedicated to the 90th anniversary of academician E.I. Chazov.