bioRxiv Science⌕ Search

Biology subjects

Wilde, M. A.

Publications and source records attributed to Wilde, M. A..

3 recordsLinked to original sources

Satellite microglia-like cells in human dorsal root ganglia and changes with diabetic neuropathy

Phagocytic and immune-like cells have been observed in the satellite envelope of neuronal somata in peripheral sensory ganglia of many species for several decades. These cells likely play an important role in normal function of sensory neurons and they may also play an important role in neuronal dysfunction and neurodegeneration seen with neuropathy. Recent findings have described a satellite macrophage population transcriptomically similar to microglia in peripheral ganglia of some mammalian species. The function of these cells, and the mechanisms by which they may influence neurons in neuropathy are unclear. We sought to understand the phenotype and localization of these cells in the human dorsal root ganglion (hDRG) using large-scale single nucleus and spatial transcriptomic datasets from individuals with and without a history of peripheral diabetic neuropathy. We observed a large population of macrophages that express classical microglia makers such as TMEM119 and P2RY12 in the hDRG, as previously described. Our findings confirm that these microglia-like cells (MLCs) localize to the satellite envelope around neuronal somata, yet are transcriptomically distinct from all glial cell types characterized in the hDRG. These MLCs exhibit changes in abundance and localization with diabetic painful neuropathy (DPN) in both the hDRG and sural nerves suggesting that they are not exclusively localized to the DRG. We conclude that microglia-like cells are likely the resident tissue macrophage (RTM) of the hDRG, and perhaps the peripheral nervous system (PNS) given their localization to the sural nerve and other ganglia, where they are predicted to regulate homeostatic neuronal functions and response to injury. HighlightsO_LIMLCs are likely the RTM of hDRGs C_LIO_LIMLCs localize to the satellite envelope and recede with Nageotte nodule formation C_LIO_LIMLC activation state and signaling shift with diabetic neuropathy C_LIO_LIMLCs are also present in other ganglia and sural nerve C_LI

neuroscience↗

T-cell distribution in the dorsal root ganglion across species, sex, and age

T-cells infiltrate somatosensory ganglia in response to nerve damage, autoimmune disease, and infection, contributing to sensory abnormalities and pain. In naive states, T-cells are rare in the rodent dorsal root ganglion (DRG) but have been reported in human and non-human primates without known relevant exposures. It remains unclear whether there are inherent evolutionary or species differences in DRG T-cell residence. Using a comparative biology approach, we investigated the frequency and distribution of T-cells in the mammalian DRG across humans, non-human primates, pigs, and rodents, and in humans investigated the contributions of sex and age. Spatial transcriptomics and immunofluorescence independently verified the robust presence of DRG T-cells at similar levels in humans, non-human primates, and pigs, but were fewer in rats and largely absent in mice. In humans, premenopausal females were more likely to have elevated DRG endoneurial T-cells than post-menopausal females or adult males. T-cells were detected in human dorsal root ganglion at as early as two months of age but were less abundant within the perineuronal niche. Most human DRG T-cells expressed distinct markers consistent with a resident memory (Trm) phenotype. We discuss the importance of studying the functional roles of DRG-resident T-cells and raise broader considerations for modelling peripheral nervous system disease.

neuroscience↗

Progressive neurodegeneration in human dorsal root ganglion from diabetes to painful neuropathy

Diabetic painful neuropathy (DPN) is characterized by neuropathic pain accompanied by loss of sensory function. We hypothesized that neurodegeneration in the dorsal root ganglion (DRG) could underlie DPN progression. To address this question, we performed multi-omic evaluation on DRGs from otherwise healthy organ donors, donors with diabetes but no neuropathy, and donors with clinically diagnosed DPN. We discovered that the first stages of neurodegeneration begin early in diabetes before the onset of DPN, with Nageotte nodule formation accompanied by apoptotic gene expression and decreased proportion of specific populations of A-fibers in DPN with remodeling of non-neuronal cells. Our findings define DPN as a neurodegenerative disorder of the DRG, identify molecular markers of disease stage, and highlight the need for early intervention to prevent irreversible neurodegeneration.

neuroscience↗