Matrix metalloproteinase 28 is regulated by TRIF- and type I IFN-dependent signaling in macrophages

Area of Science:

• Immunology
• Molecular Biology
• Extracellular Matrix Biology

Background:

• Matrix metalloproteinases (MMPs) are crucial proteases involved in extracellular matrix (ECM) remodeling and inflammation.
• Previous research identified Mmp28 as a key regulator in macrophage polarization during pulmonary inflammation.
• The specific signaling pathways controlling macrophage Mmp28 expression were previously undefined.

Purpose of the Study:

• To investigate the signaling pathways regulating macrophage Mmp28 expression.
• To test the hypothesis that TRIF and type I IFN signaling pathways control Mmp28 expression in macrophages.
• To elucidate the functional role of MMP28 in macrophage inflammatory responses.

Main Methods:

• Utilized murine macrophages from wild type and knockout mice (Tlr2^-/-, Tlr4^-/-, MyD88^-/-, Trif_mutant, Ifnar1^-/-).
• Stimulated macrophages with lipopolysaccharide (LPS) and poly(I:C).
• Analyzed Mmp28 expression and inflammatory gene expression (Ccl2, Ccl4, Cxcl10, Il6) in wild type and Mmp28^-/- macrophages.

Main Results:

• Macrophage Mmp28 expression increased following LPS and poly(I:C) stimulation, dependent on type I IFN signaling.
• TRIF signaling was also found to be critical for Mmp28 induction.
• Mmp28^-/- macrophages exhibited heightened expression of inflammatory genes (Ccl2, Ccl4, Cxcl10, Il6) upon poly(I:C) stimulation, indicating a role for MMP28 in modulating inflammation.

Conclusions:

• Macrophage Mmp28 expression is regulated by TRIF- and type I IFN-dependent signaling pathways.
• MMP28 plays a role in controlling the macrophage inflammatory response.
• These findings contribute to a model where macrophages integrate TRIF and type I IFN signaling to regulate ECM-modifying proteins.