Transcriptomic Regulation of Macrophages by Matrix-Bound Nanovesicle-Associated Interleukin-33.

Area of Science:

• Biomaterials Science
• Immunology
• Regenerative Medicine

Background:

• Macrophage phenotype critically influences biomaterial remodeling outcomes, with M2-like phenotypes promoting repair and M1-like phenotypes causing inflammation.
• Extracellular matrix (ECM)-based scaffolds, including matrix-bound nanovesicles (MBVs), can steer macrophages toward a pro-remodeling M2-like state.
• The precise mechanisms of MBV-mediated macrophage activation, particularly the role of intraluminal interleukin-33 (IL-33), require further elucidation.

Purpose of the Study:

• To investigate the gene expression signature of macrophages upon exposure to MBVs with and without intraluminal IL-33.
• To determine the role of IL-33 within MBVs in modulating macrophage phenotype, independent of its canonical ST2 receptor.
• To identify specific molecular pathways regulated by MBV-associated IL-33 that promote a pro-remodeling macrophage state.

Main Methods:

• Utilized next-generation RNA sequencing to profile gene expression in macrophages.
• Compared gene signatures of macrophages exposed to MBVs with and without intraluminal IL-33.
• Assessed macrophage responses in both wild-type and ST2-deficient (st2) models.

Main Results:

• MBV-associated IL-33 induced an anti-inflammatory (M2-like) phenotype and suppressed a pro-inflammatory (M1-like) phenotype in macrophages.
• This M2-like polarization occurred independently of the IL-33 receptor ST2.
• ST2-independent IL-33 signaling broadly regulated genes involved in inflammatory responses and immune cell crosstalk.

Conclusions:

• Intraluminal IL-33 within MBVs is a key driver of pro-remodeling M2-like macrophage activation.
• MBV-associated IL-33 promotes favorable tissue remodeling through ST2-independent signaling pathways.
• These findings provide a basis for designing advanced biomaterials and tissue engineering strategies for regenerative medicine.