Immunometabolic dysregulation in microglia drives brain ageing via neuroimmune cGAS-STING

Ageing and age-related brain disorders are typically concomitant with cellular mitochondrial dysfunction and metabolic dysregulation in immune cells. However, whether and how immunometabolic dysregulation in the brain affects neurological function are incompletely understood. Here we reveal the presence of metabolic dysregulation within microglia, the brain-resident immune cells, in aged mice. We discover that microglia with dysregulated immunometabolism, induced by dysfunctional mitochondria, initially act as triggers of brain ageing-related neurological dysfunctions in mice, which are mechanistically driven by microglial immunometabolic disturbance-induced inflammaging response depending on neuroimmune cGAS-STING pathway. We present evidence that a combined treatment targeting both metabolism and neuroinflammation partially rescues brain ageing in mice. These findings establish a causal link between immunometabolism, neuroimmunity, and brain ageing, underscoring the significance of tightly regulated immunometabolism in age-associated neurological diseases. To assess the impact of Tfam knockout on microglial cell function, we employed CRISPR-Cas9 technology to knockout Tfam in BV2 cells, and evaluated its effect on the cellular transcriptome through RNA-seq analysis.