Alpha 1-antitrypsin does not inhibit human monocyte caspase-1

Area of Science:

• Immunology
• Biochemistry
• Molecular Biology

Background:

• Alpha 1-antitrypsin (A1AT) is a protease inhibitor with potential immune modulatory functions.
• A1AT's ability to inhibit caspases, particularly caspase-1, is of interest for inflammatory conditions.

Purpose of the Study:

• To investigate the effect of Alpha 1-antitrypsin (A1AT) on caspase-1 activity in human mononuclear phagocytes.
• To determine if A1AT can modulate caspase-1-related inflammation.

Main Methods:

• Assessed caspase-1 activity using a fluorogenic substrate (WEHD-afc) in cell-free systems, cell cultures, and human whole blood.
• Quantified the release of processed IL-18 and IL-1β as indicators of caspase-1 activation.
• Tested A1AT's inhibition of neutrophil elastase (NE) as a control.

Main Results:

• A1AT did not inhibit caspase-1 activity in cell-free THP-1 lysates.
• Exogenous A1AT did not affect IL-18 release from LPS/ATP-stimulated THP-1 cells.
• A1AT failed to inhibit IL-1β processing and release in human whole blood models.

Conclusions:

• Alpha 1-antitrypsin (A1AT) does not inhibit human monocyte caspase-1 activity.
• A1AT's known neutrophil elastase inhibitory function does not extend to modulating caspase-1.