Nature, Published online: 11 November 2026; doi:10.1038/s41586-026-11308-7

IL-1β from neutrophils and macrophages stabilizes nearby brown adipocytes in a low-UCP1 state; cold temperature reduces IL-1β via sympathetic nerves, leading to transition to a high-UCP1 state and increased thermogenesis, while higher temperatures have the opposite effect.