Trained immunity in acute and chronic neurological diseases

Trained immunity, the long-term reprogramming of innate immune cells to elicit an enhanced response upon subsequent challenges, has become a key concept in understanding a wide range of pathologies, including both acute and chronic inflammatory disorders. Recent evidence suggests that trained immunity also plays a significant role in the development and progression of various neurological disorders and related comorbidities, in which brain pathology can lead to trained immunity. This review summarizes the current understanding of trained immunity within both brain-resident immune cells and myeloid-derived innate immune cells, focusing on their roles in neurological disorders, such as ischemic brain injury, Parkinson's disease, and Alzheimer's disease. Additionally, we explore the heterogeneity of trained immunity across different conditions and its potential applications in clinical neurology.