Epichaperome Remodeling Defines Layer- and Cell-Type–Specific Vulnerability in the Prefrontal Cortex of Alzheimer’s Disease Brains

Alzheimer’s disease (AD) is marked by selective vulnerability of specific neuronal populations and cortical layers, yet the molecular drivers of this pattern remain unclear. Epichaperomes—stable, multimeric assemblies of chaperones and co-chaperones—have emerged as early markers of proteome dysfunction in AD, capable of rewiring protein interaction networks without requiring changes in gene expression (Inda et al. Nature Communications 2020, DOI: 10.1038/s41467-019-14082-5; Bay et al. Res Sq [Preprint]. 2025 Feb 12:rs.3.rs-5930673. doi: 10.21203/rs.3.rs-5930673/v1). These scaffolding assemblies form in vulnerable neurons and astrocytes and drive systems-level dysfunction across synaptic, metabolic, and inflammatory pathways. Notably, epichaperome disruptors such as PU-AD (Icapamespib) have entered clinical trials in AD, highlighting the translational potential of targeting epichaperome-based remodeling.

Here, we used multiplex immunofluorescence staining and a chemical biology-based click probe to map the spatial and cell-type–specific distribution of epichaperomes in the dorsolateral prefrontal cortex (BA9) across the AD continuum. Using multiplex immunofluorescence staining of postmortem human BA9 tissue spanning non-cognitively impaired (NCI), mild cognitive impairment (MCI) and AD, we visualized epichaperome assemblies alongside neuronal (MAP2), astrocytic (GFAP), and nuclear (Hoechst) markers. We found that epichaperomes are largely absent in NCI brains but become prominent in MCI and AD, with distinct cell and layer-specific patterns. Earliest epichaperomes were observed in large pyramidal neurons of layers V and III and their neighboring astrocytes prior to over