Alpha 2-plasmin inhibitor inactivation by human granulocyte elastase

Area of Science:

• Biochemistry
• Hematology
• Enzymology

Background:

• Alpha 2-plasmin inhibitor (alpha 2-PI) plays a crucial role in regulating fibrinolysis by inhibiting plasmin.
• The spontaneous conversion of alpha 2-PI to a non-plasminogen-binding form has been previously observed.
• Human granulocyte elastase (HGE) is a serine protease involved in inflammatory processes.

Purpose of the Study:

• To elucidate the role of human granulocyte elastase in the degradation of alpha 2-plasmin inhibitor.
• To characterize the conversion process of alpha 2-PI by HGE.
• To investigate the implications of HGE-mediated alpha 2-PI degradation in fibrinolysis.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to assess protein integrity.
• Two-dimensional immunoelectrophoresis to analyze protein modifications.
• Kinetic assays to measure plasmin inhibition activity.

Main Results:

• Human granulocyte elastase converts plasminogen-binding alpha 2-plasmin inhibitor into a non-plasminogen-binding form and subsequently into an inactive form.
• This HGE-induced degradation was confirmed by SDS-PAGE, 2D immunoelectrophoresis, and functional plasmin inhibition assays.
• Inhibition of alpha 2-PI by HGE in normal human plasma required high elastase concentrations, suggesting localized rather than systemic effects.

Conclusions:

• Human granulocyte elastase actively degrades alpha 2-plasmin inhibitor, impacting fibrinolysis.
• The findings suggest HGE's role in localized fibrinolysis within specific microenvironments.
• This enzymatic activity of HGE on alpha 2-PI is unlikely to cause systemic fibrinolytic events.