BMAL1: how your body clock controls macrophage inflammation

The circadian clock controls macrophage polarization—the ability of these immune cells to shift between pro-inflammatory (M1) and anti-inflammatory (M2) states—through BMAL1, a core clock component whose activity oscillates throughout the day. Researchers found that BMAL1 transports MFP2, a fatty acid-oxidation enzyme normally sequestered in peroxisomes, into the cell nucleus, where it elevates acetyl-CoA levels and drives acetylation of p65, a critical subunit of NF-κB, the master switch for inflammatory genes. In normal mice exposed to a chemical carcinogen, pro-inflammatory M1 macrophages surged with elevated inflammatory signals; by contrast, mice with BMAL1 deleted specifically in macrophages showed significantly reduced inflammation and suppressed hepatic tumor development. These findings uncover a nuclear metabolic pathway regulated by the circadian clock that links immune timing to disease prevention, suggesting that targeting nuclear MFP2 while administering therapeutics at optimal times of day could become a novel strategy for chronic inflammatory diseases and cancer, with the dual benefit of enhanced efficacy and minimized side effects.