Your Immune Cells Are Running Your Heart, Brain, and Metabolism Too
A major review in Science argues that the immune system is far more than a defense network. Immune cells — particularly macrophages, T cells, and innate lymphoid cells — actively regulate heartbeat conduction, neuronal pruning, gut motility, fat metabolism, muscle repair, bone remodeling, and hormone production. Cardiac macrophages connected to cardiomyocytes via gap junctions help maintain electrical conduction; their removal causes lethal arrhythmia in mice. Brain-resident microglia shape memory and behavior via IL-6. Gut macrophages control peristalsis and protect the intestinal barrier from fungal toxins. Adipose macrophages regulate thermogenesis and lipid storage. The review synthesizes dozens of recent studies to reframe immunity as a core physiological system, not merely a reactive defense mechanism.