Neutrophil Protease Cleavage of Von Willebrand Factor in Glomeruli – An Anti-thrombotic Mechanism in the Kidney

• Published in: EBioMedicine 2017-02, Vol.16 (C), p.302-311
• Main Authors: Tati, Ramesh, Kristoffersson, Ann-Charlotte, Manea Hedström, Minola, Mörgelin, Matthias, Wieslander, Jörgen, van Kooten, Cees, Karpman, Diana
• Format: Article
• Language: English
• Subjects: ADAMTS13; ADAMTS13 Protein - metabolism; Adult; Basic Medicine; Blood Platelets - metabolism; Cathepsin G - metabolism; Elastase; Endothelial Cells - metabolism; Glomerular basement membrane; Glomerular Basement Membrane - drug effects; Glomerular Basement Membrane - metabolism; Humans; Immunoblotting; Immunologi inom det medicinska området; Immunology in the medical area; Kidney; Kidney - blood supply; Kidney - metabolism; Kidney - ultrastructure; Kidney Glomerulus - drug effects; Kidney Glomerulus - metabolism; Kidney Glomerulus - ultrastructure; Leukocyte Elastase - antagonists & inhibitors; Leukocyte Elastase - metabolism; Male; Matrix Metalloproteinase 9 - metabolism; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinska och farmaceutiska grundvetenskaper; Microscopy, Electron, Transmission; Myeloblastin - metabolism; Neutrophils; Neutrophils - enzymology; Peptide Hydrolases - metabolism; Proteinase Inhibitory Proteins, Secretory - pharmacology; Review; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Thrombosis - metabolism; Thrombosis - prevention & control; Von Willebrand factor; von Willebrand Factor - metabolism
• ISSN: 2352-3964; 2352-3964
• DOI: 10.1016/j.ebiom.2017.01.032

Adequate cleavage of von Willebrand factor (VWF) prevents formation of thrombi. ADAMTS13 is the main VWF-cleaving protease and its deficiency results in development of thrombotic microangiopathy. Besides ADAMTS13 other proteases may also possess VWF-cleaving activity, but their physiological importance in preventing thrombus formation is unknown. This study investigated if, and which, proteases could cleave VWF in the glomerulus. The content of the glomerular basement membrane (GBM) was studied as a reflection of processes occurring in the subendothelial glomerular space. VWF was incubated with human GBMs and VWF cleavage was assessed by multimer structure analysis, immunoblotting and mass spectrometry. VWF was cleaved into the smallest multimers by the GBM, which contained ADAMTS13 as well as neutrophil proteases, elastase, proteinase 3 (PR3), cathepsin-G and matrix-metalloproteinase 9. The most potent components of the GBM capable of VWF cleavage were in the serine protease or metalloprotease category, but not ADAMTS13. Neutralization of neutrophil serine proteases inhibited GBM-mediated VWF-cleaving activity, demonstrating a marked contribution of elastase and/or PR3. VWF-platelet strings formed on the surface of primary glomerular endothelial cells, in a perfusion system, were cleaved by both elastase and the GBM, a process blocked by elastase inhibitor. Ultramorphological studies of the human kidney demonstrated neutrophils releasing elastase into the GBM. Neutrophil proteases may contribute to VWF cleavage within the subendothelium, adjacent to the GBM, and thus regulate thrombus size. This anti-thrombotic mechanism would protect the normal kidney during inflammation and could also explain why most patients with ADAMTS13 deficiency do not develop severe kidney failure. •Neutrophil proteases in the glomerular basement membrane cleave VWF and may protect the kidney from microthrombi.•VWF cleavage would be activated by neutrophil influx and compensate for the prothrombotic mechanisms during inflammation.•This mechanism may compensate for lack of ADAMTS13 and explain why TTP patients seldom develop end-stage renal failure. The study demonstrates a mechanism by which the kidney is protected from blood clotting during inflammation. In the inflammatory setting white blood cells infiltrate tissues. In this study we showed that enzymes released from white blood cells into the kidney decrease the size of blood clots. This is a general mechanism but could also