Circadian gatekeepers of the gut–brain–immune axis: implications for neuroinflammation and neurodegeneration

Circadian rhythms, primarily regulated by light–dark cycles, play a crucial role in maintaining physiological health, including metabolism and immune responses. Evidence shows that circadian rhythms are involved in modulating gut microbiota composition, peripheral and central immune systems, and neurodegenerative disease progression. Recent research has illuminated the complex interplay between circadian rhythms and the gut microbiota-immune-brain axis. This review examines the bidirectional relationship between circadian rhythms and gut microbiota, and explores how this interaction influences brain function through the gut-brain axis, with particular focus on neuroinflammation and neurodegeneration. We aim to provide novel insights that could inform therapeutic strategies to prevent or slow down the progression of neurodegenerative diseases through circadian rhythm modulation.