Relationship of immune-inflammatory pathway and stress-induced depression with neural regeneration

Major depressive disorder is a complex psychiatric condition characterized by mood dysregulation, cognitive impairment, and somatic symptoms. Recent studies underscore the pivotal roles of neural regeneration and inflammation in its pathophysiology. This narrative review synthesizes emerging evidence linking neuroinflammatory pathways and impaired neurogenesis in major depressive disorder. We explore mechanisms including microglial activation, kynurenine pathway dysregulation, synaptic remodeling, and gut-brain axis alterations. Special emphasis is placed on recent discoveries highlighting molecular cross-talk between immune responses and neural plasticity. By mapping these interactions, we aim to advance understanding of major depressive disorder subtypes and support the development of inflammation-targeted therapies.