Biology subjects

Midavaine, E.

Publications and source records attributed to Midavaine, E..

6 recordsLinked to original sources

bioRxiv2026

Automated compartment-based quantification reveals distinct patterns of cutaneous innervation with aging and microbial colonization

Cutaneous innervation is commonly quantified using measures such as intraepidermal nerve fiber density, but these approaches capture only selected anatomical regions or features of nerve structure. We developed an automated image-analysis pipeline to quantify nerve area and nerve-skeleton length across defined epidermal and dermal compartments in whole, stitched mouse plantar skin sections. Automated epidermis-dermis boundary detection showed agreement with manual tracing within the range of inter-observer variation and produced similar downstream measurements. We then applied the pipeline to skin from mice across age and distinct microbial environmental exposures. Conventionalized mice exposed to microbes had greater nerve area and length than germ-free mice in both the epidermis and dermis. In the aging cohort, aged mice had greater dermal nerve area and length than young mice, while epidermal measurements did not differ significantly. We also analyzed the epidermis and dermis together to assess whole-skin innervation. Whole-skin nerve area and length were higher in conventionalized mice than in germ-free mice but did not differ significantly between young and aged mice. These findings show that analyzing the epidermis and dermis separately helps identify where nerve measurements differ, including differences that may not be detected when both skin layers are analyzed together. Compartment-resolved quantification therefore provides a complementary approach for studying changes in cutaneous innervation across biological conditions and behavioral outcomes.

neuroscience↗

bioRxiv2025

A neurotensin receptor type 1-derived pepducin acts as a biased allosteric modulator to regulate target receptor function

Pepducins are synthetic membrane-tethered lipopeptides designed to allosterically modulate G protein-coupled receptor (GPCR) signaling. Here, we characterize a series of pepducins targeting the neurotensin receptor type 1 (NTS1), revealing multifaceted modulation of this receptor class. Using BRET-based biosensors, we show that PP-001, a pepducin derived from NTS1s first intracellular loop, preferentially activates G protein over {beta}-arrestin signaling while inhibiting NT binding, NT-induced {beta}-arrestin recruitment, and NTS1 receptor internalization, thereby acting as biased allosteric agonist and negative allosteric modulator. PP-001 also promotes the formation of both homo- and heteromeric multi-receptor units. In vivo, PP-001 elicits potent, sustained hypotensive effects, reversible by the NTS1 antagonist SR48692. Finally, although the mechanism of pepducin-receptor interaction remains unclear, this study identifies a critical N-terminal RKK motif for PP-001s biological activity. Thermodenaturation assays with purified NTS1 and mutagenesis further provide evidence for the role of NTS1s H8 domain in direct pepducin-receptor interaction. This work highlights pepducins modulatory potential as pharmacological tools for GPCR-targeted drug development.

pharmacology and toxicology↗

bioRxiv2024

CCR2 silencing in sensory neurons blocks bone cancer progression

The peripheral nervous system contributes to cancer growth, in part by shaping the immunological niche of the tumor. How the nervous system influences bone cancer progression, and whether the underlying neuroimmune pathways can be targeted therapeutically, remain unclear. Here we demonstrate a profound influence of the peripheral nervous system on tumor progression that can be countered by silencing chemokine receptor signaling in sensory neurons. Axotomy of the tumor-innervating femoral nerve inhibits tumor progression in animals bearing bone cancer, whereas intrathecal delivery of the tumor-associated proinflammatory chemokine CCL2 promotes both tumor growth and allodynia. Silencing CCR2 in dorsal root ganglion (DRG) neurons with a newly developed lipid nanoparticle-formulated Dicer-substrate siRNA impedes tumor progression and pathological bone remodeling, and relieves bone cancer-associated pain. Mechanistically, bone cancer drives CCR2-dependent transport of substance P and CGRP along the tumor-innervating femoral nerve, and these neuropeptides expand the tumor-associated macrophage population; silencing CCR2 in DRG neurons normalizes the neuropeptide milieu and ameliorates altered bone remodeling. We thus define a targetable neuroimmune axis that contributes to cancer progression. HighlightsO_LICancer progression activates sensory neurons, driving pain hypersensitivity and neuropeptide release. C_LIO_LIAxotomy of the tumor-innervating femoral nerve impedes tumor progression. C_LIO_LICCL2-CCR2 signaling in DRG neurons promotes pain hypersensitivity and cancer growth. C_LIO_LISilencing CCR2 in the DRG reduces pain hypersensitivity, tumor-associated macrophage numbers and cancer growth. C_LI

neuroscience↗

bioRxiv2024

Sexually dimorphic regulatory T cell-derived enkephalin imparts pregnancy-induced analgesia

T cells have emerged as sex-dependent orchestrators of pain chronification but the sexually dimorphic mechanisms by which T cells control pain sensitivity is not resolved. Here, we demonstrate an influence of regulatory T cells (Tregs) on pain processing that is distinct from their canonical functions of immune regulation and tissue repair. Specifically, meningeal Tregs (mTregs) express the endogenous opioid, enkephalin, and mTreg-derived enkephalin exerts an antinociceptive action through a presynaptic opioid receptor signaling mechanism that is dispensable for immunosuppression. We demonstrate that mTregs are both necessary and sufficient to suppress mechanical pain sensitivity in female, but not male, mice, with this modulation reliant on sex hormones. These results uncover a fundamental sex-specific, and immunologically- derived endogenous opioid circuit for nociceptive regulation with critical implications for pain biology. Highlights1. Gating of allodynia by meningeal Tregs is sex hormone-dependent 3. Treg-derived enkephalin modulates mechanical pain sensitivity, not inflammation 4. Delta opioid receptor on MrgprD+ sensory neuron mediates pain processing by mTregs

immunology↗

bioRxiv2023

CCR2-targeting pepducins reduce T cell-nociceptor interaction driving bone cancer pain

Inhibition of the CCL2/CCR2 chemokine signaling represents a promising avenue for the development of non-opioid pain treatment, particularly for painful bone metastases. To investigate the involvement of CCR2 in cancer-induced bone pain, we generated and characterized the functional activities of a novel cell-penetrating pepducin, namely PP101, acting as an intracellular negative allosteric modulator of CCR2. In vivo, PP101 was effective in relieving neuropathic and bone cancer pain. By targeting CCR2, PP101 reduced bone cancer pain by preventing infiltration of CD4+ and CD8+ T cells and by decreasing the neuroimmune communication network within the dorsal root ganglia. Importantly, reduced neuroinflammatory milieu in the dorsal root ganglia induced by PP101 did not result in deleterious tumor progression or behavioral adverse effects. Thus, targeting the neuroimmune crosstalk through allosteric inhibition of CCR2 may represent an effective and safe avenue for the management of bone cancer pain. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/556569v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@15c2d43org.highwire.dtl.DTLVardef@9fa40corg.highwire.dtl.DTLVardef@cb457dorg.highwire.dtl.DTLVardef@13f36e1_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIBreast cancer bone metastases induce pain by activating CCR2 on sensory neurons. C_LIO_LIDRG-infiltrating CD4+ and CD8+ T cells promote the development of bone cancer pain. C_LIO_LICCR2 inhibition by PP101 suppresses DRG neuroinflammation and neuronal excitability. C_LIO_LIPP101 alleviates bone cancer pain without behavioral or physiological side effects. C_LI

neuroscience↗

bioRxiv2023

Tetracycline transactivator overexpression in keratinocytes triggers a TRPV1 primary sensory neuron-dependent neuropathic itch

Mouse models that combine tetracycline-controlled gene expression systems and conditional genetic activation can tightly regulate transgene expression in discrete cell types and tissues. However, the commonly used Tet-Off variant, tetracycline transactivator (tTA), when overexpressed and fully active, can lead to developmental lethality, disease, or more subtle behavioral phenotypes. Here we describe a profound itch phenotype in mice expressing a genetically encoded tTA that is conditionally activated within the Phox2a lineage. Phox2a; tTA mice develop intense, localized scratching and regional skin lesions that can be controlled by the tTA inhibitor, doxycycline. As gabapentin, but not morphine, relieved the scratching, we consider this phenotype to result from chronic neuropathic itch, not pain. In contrast to the Phox2a lineage, mice with tTA activated within the Phox2b lineage, which has many similar areas of recombination within the nervous system, did not recapitulate the scratching phenotype. In Phox2a-Cre mice, but not Phox2b-Cre, intense Cre-dependent reporter expression was found in skin keratinocytes which formed the area at which skin lesions developed. Most interestingly, repeated topical application of the DREADD agonist, CNO, which chronically induced Gi signaling in Phox2a-keratinocytes, completely reversed the localized scratching and skin lesions. Furthermore, ablation of TRPV1-expressing, primary afferent neurons reduced the scratching with a time course comparable to that produced by Gi-DREADD inhibition. These temporal properties suggest that the neuropathic itch condition arises not only from localized keratinocyte activation of peripheral nerves but also from a persistent, gabapentin-sensitive state of central sensitization.

neuroscience↗