Cytochalasin B modulates macrophage-mediated inflammatory responses

Area of Science:

• Immunology
• Cell Biology

Background:

• The actin cytoskeleton is vital for macrophage functions, including inflammatory responses.
• Its regulation by toll-like receptor (TLR) activation, particularly TLR4, is not well understood.

Purpose of the Study:

• To investigate the role of the actin cytoskeleton in macrophage activation.
• To explore the effects of cytochalasin B (Cyto B) on TLR4-mediated inflammatory responses and cellular functions.

Main Methods:

• Macrophages were treated with cytochalasin B, a TLR4 ligand (lipopolysaccharide), and other inhibitors.
• Assessed inflammatory gene expression (COX-2, TNF-α, iNOS), nitric oxide production, morphological changes, and phagocytosis.
• Analyzed protein phosphorylation (VASP, HSP27) and co-localization of MD2 with the actin cytoskeleton.

Main Results:

• Cyto B suppressed TLR4-mediated inflammatory gene expression and lipopolysaccharide-induced morphological changes without affecting cell viability.
• Nitric oxide production was reduced under non-adherent conditions.
• Cyto B and a Src inhibitor enhanced phagocytosis, and Cyto B inhibited VASP and HSP27 phosphorylation.

Conclusions:

• The actin cytoskeleton is a key regulator of TLR4-mediated inflammatory responses in macrophages.
• Targeting the actin cytoskeleton may offer therapeutic strategies for inflammatory diseases.