Modulation of Stiffness-Dependent Macrophage Inflammatory Responses by Collagen Deposition

Area of Science:

• Immunobiology
• Biomaterials Science
• Cellular Mechanosensing

Background:

• Macrophages are innate immune cells interacting with the extracellular matrix.
• Collagen is widely used in immune cell culture, but substrate functionalization is often overlooked.
• Environmental cues like matrix stiffness modulate macrophage activity.

Purpose of the Study:

• To investigate how collagen solubilization solvent affects macrophage inflammatory activation and mechanosensing.
• To determine the role of substrate organization in modulating immune cell responses.
• To understand the impact of biomaterial surface chemistry on macrophage behavior.

Main Methods:

• Solubilizing collagen in acetic acid (Col-AA) or HEPES (Col-HEP) and conjugating to polyacrylamide hydrogels.
• Culturing bone marrow-derived macrophages on functionalized hydrogels of varying stiffness.
• Analyzing inflammatory cytokine/gene expression, collagen receptor (LAIR-1) expression, and mechanosensitive molecule localization (YAP/TAZ).

Main Results:

• Col-AA surfaces induced high inflammatory cytokine and gene expression irrespective of stiffness.
• Col-HEP surfaces showed stiffness-dependent inflammatory activation.
• Macrophages on Col-AA exhibited enhanced spreading, vinculin expression, and YAP/TAZ nuclear localization compared to Col-HEP.

Conclusions:

• Solvent choice for collagen deposition critically influences macrophage inflammatory activation and mechanosensing.
• Biomaterial surface functionalization details are crucial for reproducible immunobiology studies.
• Understanding these effects is vital for designing effective immunomodulatory biomaterials.