High-dimensional Spatial Immune Profiling Highlights Microglia-Like Cells in Human Dorsal Root Ganglia

The human dorsal root ganglia (DRG) are increasingly recognized as immunologically active sites within the peripheral nervous system. While single-cell transcriptomics has recently identified myeloid populations with microglia-like profiles in DRG across species, an in-depth, spatially resolved protein-level characterization in human tissue is lacking. Here, we used highly multiplexed Imaging Mass Cytometry (IMC) to map and phenotype myeloid cells in human DRG at subcellular resolution. A 41-marker panel enabled in-depth profiling of immune and neural cell types in situ. We identified a subset of Iba1⁺ myeloid cells co-expressing canonical microglial markers such as P2RY12, TMEM119, and SLC2A5, located in close spatial proximity to neuronal somata. Unsupervised clustering (FlowSOM) of >6000 Iba1⁺ cells identified eight distinct clusters. Among them, distinct myeloid cell subsets exhibited a clear microglial-like signature and were localized near neurofilament⁺ neurons. In contrast, Iba1⁺ clusters expressing CD68, HLA-DR, and other activation markers were spatially segregated. These findings provide a spatially resolved, protein‑level atlas of Iba1⁺ myeloid subsets in human DRG and offer a resource for dissecting neuroimmune niches relevant to chronic pain and peripheral neuropathies.