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Inturi, N. N.

Publications and source records attributed to Inturi, N. N..

12 recordsLinked to original sources

E-Selectin Orchestrates IL-1B-Dependent Neuroinflammation via NLRP3 in Vincristine-Induced Neuropathy

Vincristine-induced peripheral neuropathy (VIPN) is a frequent and dose-limiting complication of cancer therapy, yet the upstream mechanisms coupling vascular activation to neuroinflammation remain poorly defined. Here we identify E-selectin as a critical orchestrator of vincristine-induced neuropathy. Systematic interrogation of endothelial adhesion molecules in a murine model of VIPN revealed that blockade of E-selectin, but not ICAM-1, PECAM-1 or P-selectin, completely prevented mechanical hypersensitivity and markedly reduced F4/80 immune cell accumulation in dorsal root ganglia and peripheral nerves. Genetic deletion of E-selectin conferred equivalent protection, despite the absence of structural loss of intraepidermal or myelinated fibres, indicating a predominantly functional neuroimmune pathology. Spatial transcriptomics demonstrated that vincristine induces a conserved stress and neuroinflammation-associated transcriptional programme in dorsal root ganglia, with immune and stromal populations acting as dominant signalling hubs. Genetic or pharmacological perturbation of E-selectin did not abolish injury-associated pathways but redistributed cell-cell communication networks, reducing immune-cell dominance and reshaping interferon and metabolic signalling states without inducing Sele expression. Mechanistically, E-selectin exerted non-canonical effects beyond endothelial adhesion. Local E-selectin administration was sufficient to induce macrophage-dependent mechanical hypersensitivity that was abolished in Fut4/7-deficient mice and following phagocyte depletion. In macrophages, E-selectin enhanced vincristine-driven NF-{kappa}B activation, NLRP3 inflammasome assembly and IL-1{beta} release. Together, these findings position E-selectin as an upstream regulator of IL-1{beta}-dependent neuroinflammation in VIPN and identify selective targeting of E-selectin-mediated immune-neuron interactions as a therapeutic strategy for chemotherapy-induced neuropathy.

neuroscience↗

A Reference Atlas of the Human Dorsal Root Ganglion

Somatosensory perception largely emerges from diverse peripheral sensory neurons whose cell bodies reside in dorsal root ganglia (DRG). Damage or dysfunction of DRG neurons is a major cause of chronic pain and sensory loss. In mice, deep single-cell transcriptomic profiling and genetically defined models have offered important clues into DRG function, but in humans, the cellular and molecular landscape of DRG neurons remains less understood. Here, we constructed a reference cell atlas of the human DRG by profiling transcriptomes of cells and nuclei from 126 donors sampled across cervical, thoracic, and lumbar DRGs. This atlas resolves 22 neuronal subtypes, including known and previously unrecognized subtypes linked to nociception, mechanosensation, thermosensation, and proprioception, as well as 10 types of non-neuronal cells. Cross-species integration, spatial transcriptomics, and microneurography enabled cell-type-specific comparisons of soma size and conduction velocity between species. Human DRG somata are larger across all cell types than their mouse counterparts, and the conduction velocities of human hair follicle innervating A-fibers are faster than in mice, suggesting a functional shift in rapid mechanical detection in humans. This integrated human DRG reference cell atlas provides a resource for exploring new molecular and physiological features of human DRG, which could help identify new strategies for treating chronic pain and other diseases of the peripheral nervous system.

neuroscience↗

A molecular map of the human spinal dorsal and ventral horn defines arrangement of neuronal types and glial sex differences

The spinal cord is the gateway for somatosensory and nociceptive information to the brain and a key locus for sensory-motor integration. Studies in mice have advanced our understanding of spinal cord circuitry, and transcriptomic studies have begun to characterize the human spinal cord; however, major gaps in knowledge persist. We conducted single-nucleus sequencing of lumbar spinal cord tissue from 11 adult organ donors and annotated spinal cord cell types with high resolution spatial transcriptomics. We identified 34 spatially and transcriptionally defined neuronal classes and detected sex-specific cell types and states across multiple glial populations. Electrophysiological recordings from dorsal horn neurons revealed firing patterns for neuronal subtypes and group I mGluR-dependent plasticity. Our work defines previously unknown aspects of human spinal cord molecular anatomy and physiology.

neuroscience↗

4E-BP2-dependent translational control in GABAergic interneurons is required for long-term memory

mRNA translational repression by eukaryotic initiation factor 4E-binding proteins (4E-BPs), plays a critical role in synaptic plasticity and the formation of long-term memory (LTM). Among the three 4E-BP paralogs, 4E-BP2 is the predominant form expressed in neurons, and its full-body deletion in mice causes memory deficits. Mice lacking 4E-BP2 in GABAergic inhibitory interneurons, but not excitatory neurons, display autistic-like behaviors and deficits in object location and recognition. The specific mRNAs translationally regulated by 4E-BP2 in GABAergic interneurons, and how they contribute to spatial and associative memory, are unknown. Here, we show that conditional knockout (cKO) mice lacking 4E-BP2 selectively in GABAergic interneurons exhibit impairments in long-term spatial and contextual fear memory formation. We further demonstrate that 4E-BP2 deletion controls the translation of selective mRNAs in interneurons without increasing general protein synthesis. One of the mRNAs is Gal, which encodes a neuropeptide that modulates memory. Our findings provide evidence that 4E-BP2 selectively controls the translation of a subset of mRNAs in inhibitory neurons that are required for LTM formation.

neuroscience↗

Peripheral nerve-targeting and pain-promoting transcriptomic signatures in early Guillain-Barr&eacute syndrome

Guillain-Barre syndrome (GBS) is an autoimmune disorder that causes weakness, sensory loss, autonomic dysfunction, and chronic neuropathic pain. The mediators responsible for driving early autoimmune injury in the most common GBS variant, acute inflammatory demyelinating polyradiculoneuropathy (AIDP), remain incompletely understood. We performed single-cell and bulk RNA sequencing on peripheral blood mononuclear cells collected from early untreated AIDP-variant GBS patients and healthy controls to comprehensively deduce leukocyte transcriptome alterations and predict disease- and pain-driving interactions between pathogenic leukocytes and peripheral nervous system cells. We found that classical, intermediate, and non-classical monocytes were expanded and upregulated genes associated with type I and II interferons, JAK/STAT signaling, and NLRP3 inflammasome engagement. CD8+ T cells were highly proliferative and likewise upregulated JAK/STAT signaling. CD4+FOXP3+ regulatory T cells upregulated PRDM1 and CD74 in a signature that may indicate functional exhaustion. A subpopulation of highly activated intermediate monocytes upregulated genes related to angiogenesis and oncostatin M. Differential expression-based cell-cell interaction analysis between GBS leukocytes, Schwann cells, and sensory neurons predicted engagement of ligand-receptor pairs with nerve integrity and pain functions, including epiregulin, interferon-beta, adrenomedullin, clusterin, IL-6, IL-15, and CCL4. Functional validation demonstrated that CCL4 sensitizes human sensory neurons in vitro. These results unearth molecular interactions by which specific leukocyte populations in AIDP-variant GBS may participate in peripheral nerve injury and drive neuropathic pain. Many of these targets may be amenable to therapeutic modulation using available approved and investigational drugs, potentially providing drug repurposing opportunities.

neuroscience↗

Spatial transcriptomic profiling of human paravertebral sympathetic chain ganglia reveals diabetes-induced neuroplasticity

The paravertebral sympathetic chain ganglia (SCG) are autonomic ganglia critical for regulating the "fight-or-flight" response. Symptoms of sympathetic dysfunction are prevalent in diabetes, affecting up to 90% of patients. The molecular and cellular composition of the human SCG and its alteration in diabetes remains poorly defined. To address this gap, we performed spatial transcriptomic profiling of lumbar SCGs from diabetic and non-diabetic organ donors. We identified 3 three distinct neuronal populations, two noradrenergic (NA1 and NA2) and one cholinergic (CHO), based on tyrosine hydroxylase (TH) and SLC18A3 expression, respectively. We also characterized 9 non-neuronal populations consisting of Schwann cells, immune cells, fibroblasts, adipocytes, and endothelial cells. In diabetic SCGs, we observed a significant loss of myelinating Schwann cells and a phenotypic shift of cholinergic neurons toward a noradrenergic identity. Additionally, diabetes was associated with a significant reduction in the transcripts of vasodilatory neuropeptides, such as VIP and CALCA, suggesting a mechanism for impaired vascular control. Upstream regulator analysis highlighted altered neurotrophic signaling in diabetes, with enhanced NGF/TRKA and diminished BDNF/TRKB activity, potentially driven by target-derived cues. Comparison between SCG and dorsal root ganglia (DRG) neurons revealed ganglia-specific genes, like SCN3A and NPY (SCG) versus SCN10A and GPX1 (DRG), offering specific therapeutic targets for autonomic dysfunction or pain. Our findings provide a transcriptomic characterization of human SCG, revealing molecular signatures that underlie diabetic autonomic dysfunction. This work lays a foundation for the development of therapies to restore sympathetic function and avoid unintended autonomic effects in the development of analgesics. Significance StatementAutonomic dysfunction affects up to 90% of people with diabetes, yet the human sympathetic nervous system remains poorly molecularly defined. To address this gap, we present a spatial transcriptomic profile of the human sympathetic chain ganglia (SCG), revealing how diabetes affects the human autonomic nervous system. We show that diabetes shifts the cholinergic neuronal population to a noradrenergic phenotype and reduces vasodilation neuropeptide expression, potentially explaining impaired vascular control and thermoregulation. Comparative analysis of sympathetic and sensory ganglia reveals distinct gene profiles that may inform novel therapeutic strategies. These findings offer critical insight into the molecular drivers of diabetic autonomic neuropathy and lay the groundwork for safer, more precise treatments that selectively modulate autonomic or sensory function in chronic disease.

neuroscience↗

Single-cell characterization of the human C2 dorsal root ganglion recovered from C1-2 arthrodesis surgery: implications for neck pain

Neurons in the dorsal root ganglion (DRG) receive and transmit sensory information from the tissues they innervate and from the external environment. Upper cervical (C1-C2) DRGs are functionally unique as they receive input from the neck, head, and occipital cranial dura, the latter two of which are also innervated by the trigeminal ganglion (TG). The C2 DRG also plays an important role in neck pain, a common and disabling disorder that is poorly understood. Advanced transcriptomic approaches have significantly improved our ability to characterize RNA expression patterns at single-cell resolution in the DRG and TG, but no previous studies have characterized the C2 DRG. Our aim was to use single-nucleus and spatial transcriptomic approaches to create a molecular map of C2 DRGs from patients undergoing arthrodesis surgery with ganglionectomy. Patients with acute (<3 months) or chronic ([&ge;]3 months) neck pain were enrolled and completed patient-reported outcomes and quantitative sensory testing prior to surgery. C2 DRGs were characterized with bulk, single nucleus, and spatial RNA sequencing technologies from 22 patients. Through a comparative analysis to published datasets of the lumbar DRG and TG, neuronal clusters identified in both TG and DRG were identified in the C2 DRG. Therefore, our study definitively characterizes the molecular composition of human C2 neurons and establishes their similarity with unique characteristics of subsets of TG neurons. We identified differentially expressed genes in endothelial, fibroblast and myelinating Schwann cells associated with chronic pain, including FGFBP2, C8orf34 and EFNA1 which have been identified in previous genome and transcriptome wide association studies (GWAS/TWAS). Our work establishes an atlas of the human C2 DRG and identifies altered gene expression patterns associated with chronic neck pain. This work establishes a foundation for the exploration of painful disorders in humans affecting the cervical spine.

neuroscience↗

Molecular architecture of human dermal sleeping nociceptors

Human dermal sleeping nociceptors display ongoing activity in neuropathic pain, affecting 10% of the population. Despite advances in rodents, a molecular marker for these mechano-insensitive C-fibers (CMis) in human skin remains elusive, preventing targeted therapy. In this translational Patch-seq study, we combine single-cell transcriptomics following electrophysiological characterization with single-nucleus and spatial transcriptomics from pigs and humans. We functionally identified CMis in pig sensory neurons with patch-clamp using adapted protocols from human microneurography. We identified oncostatin-M-receptor (OSMR) and somatostatin (SST) as marker genes for CMis. Following dermal injection in healthy human volunteers, oncostatin-M, the ligand of OSMR, exclusively modulates CMis. We identified the entire molecular architecture of human dermal sleeping nociceptors, providing new therapeutic targets and the basis for a mechanistic understanding of neuropathic pain. One Sentence SummaryWe identify the molecular architecture and specifically OSMR and SST as molecular markers for human dermal sleeping nociceptors, key players in the generation of neuropathic pain. Short versionIn this Patch-seq study, we identify OSMR and SST as molecular markers for human dermal sleeping nociceptors, key players in the generation of neuropathic pain.

neuroscience↗

Persistent changes in nociceptor translatomes govern hyperalgesic priming in mouse models

Hyperalgesic priming is a model system that has been widely used to understand plasticity in painful stimulus-detecting sensory neurons, called nociceptors. A key feature of this model system is that following priming, stimuli that do not normally cause hyperalgesia now readily provoke this state. We hypothesized that hyperalgesic priming occurs due to reorganization of translation of mRNA in nociceptors. To test this hypothesis, we used paclitaxel treatment as the priming stimulus and translating ribosome affinity purification (TRAP) to measure persistent changes in mRNA translation in Nav1.8+ nociceptors. TRAP sequencing revealed 161 genes with persistently altered mRNA translation in the primed state. We identified Gpr88 as upregulated and Metrn as downregulated. We confirmed a functional role for these genes, wherein a GPR88 agonist causes pain only in primed mice and established hyperalgesic priming is reversed by Meteorin. Our work demonstrates that altered nociceptor translatomes are causative in producing hyperalgesic priming.

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Translational control in the spinal cord regulates gene expression and pain hypersensitivity in the chronic phase of neuropathic pain

Sensitization of spinal nociceptive circuits plays a crucial role in neuropathic pain. This sensitization depends on new gene expression that is primarily regulated via transcriptional and translational control mechanisms. The relative roles of these mechanisms in regulating gene expression in the clinically relevant chronic phase of neuropathic pain are not well understood. Here, we show that changes in gene expression in the spinal cord during the chronic phase of neuropathic pain are substantially regulated at the translational level. Downregulating spinal translation at the chronic phase alleviated pain hypersensitivity. Cell-type-specific profiling revealed that spinal inhibitory and excitatory neurons exhibited substantial changes in translation after peripheral nerve injury. Notably, increasing translation selectively in all inhibitory neurons or parvalbumin-positive (PV+) interneurons, but not excitatory neurons, promoted mechanical pain hypersensitivity. Furthermore, increasing translation in PV+ neurons decreased their intrinsic excitability and spiking activity. Conversely, reducing translation in spinal PV neurons prevented the nerve injury-induced decrease in excitability but did not alleviate mechanical hypersensitivity. Together, these findings advance our understanding of translational control mechanisms in the spinal cord during neuropathic pain and highlight their cell-type- and phase-specific contributions to gene expression and pain hypersensitivity.

neuroscience↗

Deciphering the molecular landscape of human peripheral nerves: implications for diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is a prevalent complication of diabetes mellitus that is caused by metabolic toxicity to peripheral axons. We aimed to gain deep mechanistic insight into the disease process using bulk and spatial RNA sequencing on tibial and sural nerves recovered from lower leg amputations in a mostly diabetic population. First, our approach comparing mixed sensory and motor tibial and purely sensory sural nerves shows key pathway differences in affected nerves, with distinct immunological features observed in sural nerves. Second, spatial transcriptomics analysis of sural nerves reveals substantial shifts in endothelial and immune cell types associated with severe axonal loss. We also find clear evidence of neuronal gene transcript changes, like PRPH, in nerves with axonal loss suggesting perturbed RNA transport into distal sensory axons. This motivated further investigation into neuronal mRNA localization in peripheral nerve axons generating clear evidence of robust localization of mRNAs such as SCN9A and TRPV1 in human sensory axons. Our work gives new insight into the altered cellular and transcriptomic profiles in human nerves in DPN and highlights the importance of sensory axon mRNA transport as an unappreciated potential contributor to peripheral nerve degeneration.

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Epigenomic landscape of the human dorsal root ganglion: sex differences and transcriptional regulation of nociceptive genes

Gene expression is influenced by chromatin architecture via controlled access of regulatory factors to DNA. To better understand gene regulation in the human dorsal root ganglion (hDRG) we used bulk and spatial transposase-accessible chromatin technology followed by sequencing (ATAC-seq). Using bulk ATAC-seq, we detected that in females diverse differentially accessible chromatin regions (DARs) mapped to the X chromosome and in males to autosomal genes. EGR1/3 and SP1/4 transcription factor binding motifs were abundant within DARs in females, and JUN, FOS and other AP-1 factors in males. To dissect the open chromatin profile in hDRG neurons, we used spatial ATAC-seq. The neuron cluster showed higher chromatin accessibility in GABAergic, glutamatergic, and interferon-related genes in females, and in Ca2+-signaling-related genes in males. Sex differences in transcription factor binding sites in neuron-proximal barcodes were consistent with the trends observed in bulk ATAC-seq data. We validated that EGR1 expression is biased to female hDRG compared to male. Strikingly, XIST, the long-noncoding RNA responsible for X inactivation, hybridization signal was found to be highly dispersed in the female neuronal but not non-neuronal nuclei suggesting weak X inactivation in female hDRG neurons. Our findings point to baseline epigenomic sex differences in the hDRG that likely underlie divergent transcriptional responses that determine mechanistic sex differences in pain.

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