Alpha-1 antitrypsin modulates neutrophil phenotype and function: implications for inflammatory regulation

Area of Science:

• Immunology
• Cell Biology
• Protease Inhibition

Background:

• Alpha-1 antitrypsin (AAT) is the primary protease inhibitor in plasma.
• AAT regulates neutrophil function in inflammation.
• Mechanisms of AAT's role in neutrophil trafficking are poorly understood.

Purpose of the Study:

• To investigate the role of AAT in neutrophil polarity, migration, and tissue infiltration.
• To elucidate the molecular mechanisms by which AAT influences neutrophil function.

Main Methods:

• Utilized alpha-1 antitrypsin-knockout (KO) mice and in vitro assays.
• Analyzed neutrophil mobilization, liver infiltration, CD44 expression, F-actin polarization, and chemotaxis.
• Investigated signaling pathways (ERK1/2) and chemokine expression (CXCL1, CXCL10).

Main Results:

• AAT-KO mice showed impaired neutrophil mobilization and liver infiltration.
• AAT-KO neutrophils exhibited reduced CD44 expression, defective F-actin polarization, and impaired chemotaxis.
• AAT deficiency led to altered ERK1/2 activation and chemokine profiles, affecting neutrophil recruitment and phagocytosis.

Conclusions:

• Alpha-1 antitrypsin is essential for neutrophil polarity, directional migration, and tissue infiltration.
• AAT regulates neutrophil adhesion and transmigration via CD44 expression.
• Circulating AAT is critical for maintaining neutrophil immune function and signaling, with implications for AAT deficiency-related inflammatory diseases.