Synergy between a plasminogen cascade and MMP-9 in autoimmune disease

Area of Science:

• Immunodermatology
• Proteolysis
• Autoimmune Blistering Diseases

Background:

• Extracellular proteolysis by plasminogen/plasmin (Plg) and matrix metalloproteinases (MMPs) is vital in autoimmune and inflammatory diseases.
• Dermal-epidermal separation is a hallmark of blistering diseases like bullous pemphigoid (BP).

Purpose of the Study:

• To investigate the synergistic roles of the Plg cascade and MMP-9 in experimental bullous pemphigoid.
• To elucidate the molecular mechanisms underlying dermal-epidermal separation in BP.

Main Methods:

• Induction of experimental BP in mice using antibodies against BP180.
• Utilizing genetically modified mice deficient in MMP-9, Plg, tPA, uPA, and MMP-3.
• Assessing BP development and MMP-9 activation levels in reconstituted mouse models.

Main Results:

• Mice deficient in MMP-9 were resistant to experimental BP.
• Plg-deficient mice showed delayed and less severe blistering.
• The plasminogen system was found to be epistatic to MMP-9 activation in dermal-epidermal separation.

Conclusions:

• The plasminogen/plasmin system plays a critical, upstream role in initiating dermal-epidermal separation in bullous pemphigoid.
• Plasminogen activation is essential for MMP-9 activity and subsequent blister formation.
• This study clarifies the proteolytic cascade driving BP pathogenesis.