Abstract / Summary
Abstract Major depressive disorder (MDD) involves frontal cortical dysfunction, with emerging evidence implicating gliovascular and immune mechanisms, yet its transcriptional signatures across subregions, cell-types, and molecular layers remain poorly defined. Here, we integrated bulk-tissue RNA-seq data from dlPFC, mPFC, and dACC (n = 286) to identify a conserved core transcriptional profile, anchored in downregulated interneuron markers, and upregulated immune and vascular genes, spatially enriched in leptomeninges and white matter. Concordantly, multiomic factor analysis revealed immune activation, stress-response, and accelerated aging in MDD. Analysis of snRNA-seq data from dlPFC, mPFC, and oFC (863,511 nuclei; n = 204) revealed most pronounced MDD signatures in excitatory neurons, accompanied by coordinated disruption of glucocorticoid receptor machinery across cell-types, including FKBP5 upregulation. Glial, immune, and perivascular populations exhibited signatures of oxidative stress, ECM remodeling, and reduced neuronal support, and greater concordance with bulk-tissue MDD signals than neurons. A global reduction in cell-to-cell communications in MDD revealed a shift from homeostatic neuronal signaling toward endothelial and myelination-associated pathways. Ephrin-Eph signaling was consistently dysregulated, implicating disrupted axonal guidance, synaptic remodeling, and neurovascular integrity. Notably, MDD signatures were shared between MDD-only and PTSD comorbid cases at bulk-tissue analyses, while diverging at single-cell resolution. Together, these findings reframe MDD as a distributed frontal cortex disorder, driven by disrupted neuroglial and neurovascular communication.