Schizophrenia-linked gene expression changes across cortical layers and cellular microenvironments in human prefrontal cortex [Visium]

Molecular mechanisms underlying dorsolateral prefrontal cortex (dlPFC) dysfunction in schizophrenia (SCZ) are poorly understood. dlPFC cell types are spatially organized across the six layers into functional microcircuits, which regulate cognitive and emotional processes that are implicated in SCZ. While regional specificity across cortical layers and cell types has been demonstrated for some SCZ-linked genes, spatially-resolved transcriptomics (SRT) can more definitively map molecular associations of disease. We investigated spatial gene expression changes in the human dlPFC from neurotypical control (n=31) and SCZ (n=32) brain donors using the Visium platform with incorporation of immunostaining to label perineuronal nets, neurons and vasculature. SCZ-associated DEGs were then mapped across these labeled cellular microenvironments and cortical layers. Major transcriptional alterations were identified in synaptic and neuroimmune pathways, which we localized to neuropil and glia-enriched domains. Integrative analysis with bulk and single-cell RNA studies highlighted distinct roles for spatially-localized glial cell populations, and identified enrichment of novel DEGs in endothelial cells and microglia. These findings were supported by enrichment of SCZ genetic risk across similar domains, and association of laminae-specific transcription factors to SCZ risk variants. Cellular resolution SRT using Xenium extended laminar disease associations to spatially-organized cell types. The findings highlight unique advantages of SRT to identify novel SCZ-related biology, particularly for cellular populations and compartments that may be missed with alternative technologies. We provide data resources to enable sample-level visualization of the spatial transcriptomics data (Samui) and to explore SCZ-associated DEGs across spatial domains (iSEE-layer adjusted) and cellular microenvironments (iSEE-Neuropil, iSEE-Neuron, iSEE-vasculature, iSEE-PNNs). Overall design: The study includes fresh-frozen postmortem human brain tissue sections obtained from the dorsolateral prefrontal cortex (DLPFC) of 32 donors with schizophrenia (SCZ) and 31 neurotypical controls (NTC). A single 10-µm-thick cryosection per donor was analyzed using the 10x Genomics Visium spatial transcriptomics platform (v1, 3' Gene Expression), yielding a total of 63 samples. The primary comparison was made between diagnostic groups: 32 SCZ samples and 31 NTC samples.