Calcium Signaling in Macrophages During a Wound Response In Vivo

Area of Science:

• Immunology
• Cell Biology
• Physiology

Background:

• Macrophages are key immune cells involved in tissue repair and wound healing.
• Calcium (Ca2+) signaling is vital for immune cell function, but its role in macrophages during in vivo injury response is unclear.

Purpose of the Study:

• To investigate macrophage calcium (Ca2+) dynamics in response to tissue injury in live zebrafish and Danionella.
• To understand the sources and functional significance of these Ca2+ signals during early wound healing.

Main Methods:

• Utilized transgenic zebrafish and Danionella models expressing the Ca2+ indicator GCaMP in macrophages.
• Employed live confocal imaging to monitor intracellular Ca2+ transients in macrophages at wound sites.
• Used pharmacological interventions to probe the contribution of endoplasmic reticulum Ca2+ stores.

Main Results:

• Tissue injury rapidly recruits macrophages to the wound site.
• Macrophages exhibit sustained, repetitive intracellular Ca2+ transients for hours post-injury.
• Endoplasmic reticulum Ca2+ stores are essential for maintaining these Ca2+ transients, with other sources also contributing.
• These Ca2+ transients are not required for early-stage macrophage chemotaxis, phagocytosis, or TNFα activation.

Conclusions:

• Uncovered a novel pattern of macrophage Ca2+ signaling during in vivo tissue injury.
• Highlighted the complexity of Ca2+ regulation in macrophages during wound healing.
• Suggests that these specific Ca2+ transients may not be essential for initial wound response functions but indicate a unique cellular behavior.