C1 inhibitor, a multi-functional serine protease inhibitor

Area of Science:

• Immunology
• Biochemistry
• Molecular Biology

Background:

• C1 inhibitor (C1INH) is a serpin regulating complement and contact systems.
• C1INH deficiency causes hereditary angioedema, primarily mediated by bradykinin.
• Emerging evidence highlights C1INH's protease-independent anti-inflammatory functions.

Purpose of the Study:

• To review the multifaceted roles of C1INH beyond its classical protease inhibitory functions.
• To explore C1INH's interactions with leukocytes, endothelial cells, and extracellular matrix.
• To summarize C1INH's therapeutic potential in various inflammatory and infectious disease models.

Main Methods:

• Literature review of studies on C1INH function and therapeutic applications.
• Analysis of C1INH's molecular interactions and signaling pathways.
• Examination of preclinical data from disease models.

Main Results:

• C1INH exhibits anti-inflammatory effects by modulating leukocyte-endothelial interactions and suppressing inflammatory mediators.
• C1INH directly interacts with endotoxin, mitigating sepsis and endotoxin shock.
• C1INH treatment demonstrates efficacy in diverse models, including sepsis, ischemia-reperfusion injury, and transplant rejection.

Conclusions:

• C1INH possesses significant anti-inflammatory and protective functions independent of its protease inhibitory activity.
• These novel mechanisms contribute to C1INH's therapeutic benefits in a wide range of inflammatory diseases.
• Further research into C1INH's non-proteolytic functions may unlock new therapeutic strategies.