Intestinal γδ T17-IL-17A signaling disrupts hippocampal mitophagy in stress-induced depression and is restored by arketamine.
Journal of neuroinflammation December 18, 2025 Mengqi Han, Bing Xie, Yuan Yu et al.
Chronic stress triggers depression by activating a gut-immune-brain pathway. In mice exposed to chronic restraint stress, gut microbiota changes caused small intestinal γδ T cells to migrate to the brain, where they released interleukin-17A (IL-17A). This IL-17A impaired a mitochondrial cleanup process called mitophagy in the hippocampus, leading to reduced energy production, damaged synapses, and depression-like behavior. Blocking γδ T cell migration, removing a key receptor on these cells, or giving the antidepressant arketamine all restored mitophagy and improved behavior. The findings identify a specific chain from gut microbes to immune cells to brain mitochondria that drives stress-induced depression, and point to arketamine as a potential treatment targeting this pathway.