Epithelial multicellular clustering enabled by polarized macrophages on soft matrices.

Area of Science:

• Cell Biology
• Immunology
• Biomaterials Science

Background:

• Epithelial structure formation is vital for organogenesis, tumor growth, and wound repair.
• The influence of immune cells and microenvironmental mechanics on epithelial clustering remains largely unexplored.

Approach:

• Co-cultured human mammary epithelial cells with M0, M1 (proinflammatory), or M2 (anti-inflammatory) macrophages on soft or stiff hydrogels.
• Investigated epithelial cell migration, multicellular clustering, focal adhesions, and extracellular matrix deposition.
• Analyzed the role of cellular forces via Rho-associated kinase (ROCK) inhibition and quantified cytokine secretion (TNF-α, TGF-β).

Key Points:

• M1 macrophages on soft matrices significantly enhanced epithelial cell migration and multicellular clustering.
• Stiff matrices impeded epithelial clustering by increasing cell-matrix adhesion and focal adhesion stability.
• Soft matrices combined with M1 macrophages modulated fibronectin deposition and non-muscle myosin-IIA expression, optimizing clustering conditions.
• Macrophage-derived cytokines, including TNF-α and TGF-β, influenced epithelial clustering, with exogenous TGF-β promoting clustering.

Conclusions:

• Epithelial clustering is tunable by optimizing both mechanical (matrix stiffness) and immune (macrophage polarization) factors.
• Findings suggest implications for understanding and manipulating processes like tumor growth, fibrosis, and wound healing.