The complement and contact activation systems: partnership in pathogenesis beyond angioedema

Area of Science:

• Biochemistry
• Immunology
• Molecular Biology

Background:

• Blood plasma contains four key proteolytic cascades: complement, clotting, fibrinolytic, and kallikrein-kinin systems.
• These cascades share evolutionary origins and similar activation patterns.
• Interactions between these systems, particularly complement and kinin, are vital in inflammatory diseases.

Purpose of the Study:

• To review the consequences of complement and kinin system interplay.
• To highlight the role of gC1qR as a molecular link between these systems.
• To explore the involvement of this cross-talk in inflammatory diseases and cancer.

Main Methods:

• Literature review focusing on the interplay between complement and kinin systems.
• Emphasis on the function of gC1qR as a multiligand binding protein.
• Analysis of how this interaction contributes to disease pathogenesis.

Main Results:

• gC1qR acts as a receptor for C1q, high molecular weight kininogen (HK), and factor XII (FXII).
• Activation at inflammatory sites generates vasoactive peptides contributing to disease.
• This interplay is implicated in angioedema, cancer survival, and metastasis.

Conclusions:

• The interaction between complement and kinin systems, mediated by gC1qR, is a significant factor in inflammatory diseases.
• Tumors may exploit byproducts of these systems for growth and colonization.
• Further research into this cross-talk could reveal novel therapeutic targets.