Biology subjects

Chiu, I.

Publications and source records attributed to Chiu, I..

12 recordsLinked to original sources

bioRxiv2026

Pain Matters: Nociceptive signaling drives neural encoding of inflammatory responses

Pain is a cardinal sign of inflammation, constructed by the brain from peripheral nociceptive input. Yet, its role in the brain's response to inflammation remains unknown. Here, we demonstrate that nociceptive signaling is essential for the brain to represent and replay inflammatory states. Analysis of human fMRI and mouse activity mapping revealed that peripheral inflammation generates a distinct brain state. In mice, ablation of TRPV1+ sensory neurons or pharmacological analgesia disrupted this organization and prevented the insular cortex from forming retrievable immune representations. Conversely, augmenting nociceptive signaling during inflammation strengthened subsequent immune recall. These findings identify nociceptive input as a critical signal in brain-immune dialogue, enabling the encoding and retrieval of inflammatory events.

neuroscience↗

bioRxiv2024

Gasdermin D is activated but does not drive neurodegeneration in SOD1G93A model of ALS: Implications for targeting pyroptosis

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron loss, microgliosis, and neuroinflammation. While pyroptosis, an inflammatory form of programmed cell death, has been implicated in ALS, the specific role of Gasdermin D (GSDMD) - the primary executioner of pyroptosis - remains unexplored. In this study, we examined the function of GSDMD in the well-established SOD1G93A mouse model of ALS. Our results showed robust GSDMD activation in the spinal cords of SOD1G93A animals across two strain backgrounds, with elevated expression in Iba1+ microglia. To explore its role in disease progression, we bred B6.SOD1G93A mice onto a GSDMD-deficient background. In comparing SOD1G93A; Gsdmd+/+ and SOD1G93A; Gsdmd-/- mice, we found that Gsdmd loss did not affect disease onset, weight loss, or grip strength decline in either male or female animals. Notably, GSDMD deficiency resulted in a modest but statistically significant increase in mortality in SOD1G93A mice. Moreover, GSDMD absence had minimal impact on astrogliosis, microgliosis and motor neuron loss. These findings show that while GSDMD is activated in the ALS mouse model, its loss does not mitigate key ALS behavioral phenotypes, gliosis or motor neuron loss. This study provides insights into the potential therapeutic relevance of targeting pyroptosis and inflammatory pathways in ALS.

neuroscience↗

bioRxiv2024

The meninges host a unique compartment of regulatory T cells that bulwarks adult hippocampal neurogenesis

Our knowledge about the meningeal immune system has recently burgeoned, particularly our understanding of how innate and adaptive effector cells are mobilized to meet brain challenges. However, information on how meningeal immunocytes guard brain homeostasis in healthy individuals remains sparse. This study highlights the heterogeneous and polyfunctional regulatory-T (Treg) cell compartment in the meninges. A Treg subtype specialized in controlling Th1-cell responses and another known to control responses in B-cell follicles were substantial components of this compartment, foretelling that punctual Treg-cell ablation rapidly unleashed interferon-gamma production by meningeal lymphocytes, unlocked their access to the brain parenchyma, and altered meningeal B-cell profiles. Distally, the hippocampus assumed a reactive state, with morphological and transcriptional changes in multiple glial-cell types; within the dentate gyrus, neural stem cells showed exacerbated death and desisted from further differentiation, associated with inhibition of spatial-reference memory. Thus, meningeal Treg cells are a multifaceted bulwark to brain homeostasis at steady-state. One sentence summaryA distinct population of regulatory T cells in the murine meninges safeguards homeostasis by keeping local interferon-{gamma}-producing lymphocytes in check, thereby preventing their invasion of the parenchyma, activation of hippocampal glial cells, death of neural stem cells, and memory decay.

immunology↗

bioRxiv2023

The neuroimmune CGRP-RAMP1 axis tunes cutaneous adaptive immunity to the microbiota

The somatosensory nervous system surveils external stimuli at barrier tissues, regulating innate immune cells under infection and inflammation. The roles of sensory neurons in controlling the adaptive immune system, and more specifically immunity to the microbiota, however, remain elusive. Here, we identified a novel mechanism for direct neuroimmune communication between commensal-specific T lymphocytes and somatosensory neurons mediated by the neuropeptide Calcitonin Gene-Related Peptide (CGRP) in the skin. Intravital imaging revealed that commensal-specific T cells are in close proximity to cutaneous nerve fibers in vivo. Correspondingly, we observed upregulation of the receptor for the neuropeptide CGRP, RAMP1, in CD8+ T lymphocytes induced by skin commensal colonization. Neuroimmune CGRP-RAMP1 signaling axis functions in commensal-specific T cells to constrain Type 17 responses and moderate the activation status of microbiota-reactive lymphocytes at homeostasis. As such, modulation of neuroimmune CGRP-RAMP1 signaling in commensal-specific T cells shapes the overall activation status of the skin epithelium, thereby impacting the outcome of responses to insults such as wounding. The ability of somatosensory neurons to control adaptive immunity to the microbiota via the CGRP-RAMP1 axis underscores the various layers of regulation and multisystem coordination required for optimal microbiota-reactive T cell functions under steady state and pathology. Significance statementMultisystem coordination at barrier surfaces is critical for optimal tissue functions and integrity, in response to microbial and environmental cues. In this study, we identified a novel neuroimmune crosstalk mechanism between the sensory nervous system and the adaptive immune response to the microbiota, mediated by the neuropeptide CGRP and its receptor RAMP1 on skin microbiota-induced T lymphocytes. The neuroimmune CGPR-RAMP1 axis constrains adaptive immunity to the microbiota and overall limits the activation status of the skin epithelium, impacting tissue responses to wounding. Our study opens the door to a new avenue to modulate adaptive immunity to the microbiota utilizing neuromodulators, allowing for a more integrative and tailored approach to harnessing microbiota-induced T cells to promote barrier tissue protection and repair.

immunology↗

bioRxiv2023

Disruption of Epithelium Integrity by Inflammation-Associated Fibroblasts through Prostaglandin Signaling

Inflammation-associated fibroblasts (IAFs) are associated with the progression and drug resistance of chronic inflammatory diseases such as inflammatory bowel disease (IBD), but their direct impact on epithelial function and architecture is unknown. In this study, we developed an in vitro model whereby human colon fibroblasts are induced to become IAFs by specific cytokines and recapitulate key features of IAFs in vivo. When co-cultured with patient-derived colon organoids (colonoids), IAFs induced rapid colonoid swelling and barrier disruption due to swelling and rupture of individual epithelial cells. Epithelial cells co-cultured with IAFs also exhibit increased DNA damage, mitotic errors, and proliferation arrest. These IAF-induced epithelial defects are mediated through a paracrine pathway involving prostaglandin E2 (PGE2) and the PGE2 receptor EP4, leading to PKA-dependent activation of the CFTR chloride channel. Importantly, EP4-specific chemical inhibitors effectively prevented colonoid swelling and restored normal proliferation and genome stability of IAF-exposed epithelial cells. These findings reveal a mechanism by which IAFs could promote and perpetuate IBD and suggest a potential treatment to mitigate inflammation-associated epithelial injury. TeaserInflammation-associated fibroblasts compromise colon epithelial barrier integrity and genome stability via PGE2-EP4 signaling.

cell biology↗

bioRxiv2023

Induction of antiviral Interferon-Stimulated Genes (ISGs) by neuronal STING promotes the resolution of pain

Inflammation and pain are intertwined responses to injury, infection, or chronic diseases. While acute inflammation is essential in determining pain resolution and opioid analgesia, maladaptive processes occurring during resolution can lead to the transition to chronic pain. Here we found that inflammation activates the cytosolic DNA-sensing protein Stimulator of Interferon Genes (STING) in DRG nociceptors. Neuronal activation of STING promotes signaling through TANK-binding kinase 1 (TBK1) and triggers an interferon-beta (IFN{beta}) response that mediates pain resolution. Notably, we found that mice expressing a nociceptor-specific gain-of-function mutation in STING exhibited an IFN gene signature that reduced nociceptor excitability and inflammatory hyperalgesia through a KChIP1-Kv4.3 regulation. Our findings reveal a role of IFN-regulated genes (IRGs) and KChIP1 downstream of STING, in the resolution of inflammatory pain.

neuroscience↗

bioRxiv2023

A DRG genetic toolkit reveals molecular, morphological, and functional diversity of somatosensory neuron subtypes

Mechanical and thermal stimuli acting on the skin are detected by morphologically and physiologically distinct sensory neurons of the dorsal root ganglia (DRG). Achieving a holistic view of how this diverse neuronal population relays sensory information from the skin to the central nervous system (CNS) has been challenging with existing tools. Here, we used transcriptomic datasets of the mouse DRG to guide development and curation of a genetic toolkit to interrogate transcriptionally defined DRG neuron subtypes. Morphological analysis revealed unique cutaneous axon arborization areas and branching patterns of each subtype. Physiological analysis showed that subtypes exhibit distinct thresholds and ranges of responses to mechanical and/or thermal stimuli. The somatosensory neuron toolbox thus enables comprehensive phenotyping of most principal sensory neuron subtypes. Moreover, our findings support a population coding scheme in which the activation thresholds of morphologically and physiologically distinct cutaneous DRG neuron subtypes tile multiple dimensions of stimulus space.

neuroscience↗

bioRxiv2022

Neuronal-immune Axis Alters Pain and Sensory Afferent Damage During Dental Pulp Injury

Dental pulp tissue is densely innervated by afferent fibers of the trigeminal ganglion. When bacteria cause dental decay near the pulpal tissue, a strong neuronal and immune response occur, creating pulpitis, which is associated with severe pain and pulp tissue damage. Neuro-immune interactions have the potential to modulate both the pain and pathological outcome of pulpitis. We first investigated the role of the neuropeptide calcitonin-gene related peptide (CGRP), released from peptidergic sensory afferents, in dental pain and immune responses by using calca knock out (calca-/-) and wild type (calca+/+) mice, in a model of pulpitis by creating a mechanical exposure of the dental pulp horn. While CGRP did not contribute to facial mechanical hypersensitivity, at an early time point, it did contribute to spontaneous pain-like behavior. We also found that CGRP contributed to recruitment of neutrophils and monocytes, while not clearly affecting the progression of pulpal pathology histologically. When we depleted neutrophils and monocytes, we found that there was more sensory afferent loss, tissue damage and deeper spread of bacteria into the pulp tissue, while there was a reduction in facial mechanical hypersensitivity compared to control animals at a later time point. Overall, we showed that there is a crosstalk between peptidergic neurons and neutrophils in the pulp, modulating the pain and inflammatory outcomes of the disease.

neuroscience↗

bioRxiv2022

Gasdermin-E mediates mitochondrial damage in axons and neurodegeneration

Mitochondrial dysfunction and axon loss are hallmarks of neurologic diseases. Gasdermin (GSDM) proteins are executioner pore-forming molecules that mediate cell death, yet their roles in the central nervous system (CNS) are not well understood. Here, we find that one GSDM family member, GSDME is expressed by both mouse and human neurons. GSDME plays a role in mitochondrial damage and axon loss. Mitochondrial neurotoxins induced caspase-dependent GSDME cleavage and rapid localization to mitochondria in axons, where GSDME promoted mitochondrial depolarization, trafficking defects, and neurite retraction. The frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS)-associated proteins TDP-43 and PR-50 induced GSDME-mediated damage to mitochondria and neurite loss. GSDME deficiency prolonged survival, ameliorated motor dysfunction, and rescued motor neuron loss in the SOD1G93A mouse model of ALS. GSDME knockdown also protected against neurite loss in ALS patient iPSC-derived motor neurons. Thus, we identify GSDME as an executioner of neuronal mitochondrial dysfunction that contributes to neurodegeneration. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/513927v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@113c13dorg.highwire.dtl.DTLVardef@1f3c5caorg.highwire.dtl.DTLVardef@13e75adorg.highwire.dtl.DTLVardef@19fdc93_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIGSDME is expressed by neurons and activated by mitochondrial neurotoxins C_LIO_LIActivated GSDME drives axonal mitochondrial damage and neurite loss prior to cell death C_LIO_LIALS/FTD associated TDP-43 and PR-50 induces GSDME-driven neurite loss in mouse and human iPSC-derived neurons. C_LIO_LISOD1G93A mice show ameliorated disease progression and motor neuron loss in absence of GSDME C_LI

neuroscience↗

bioRxiv2022

Reprogramming brain immunosurveillance with engineered cytokines

Immune surveillance of the brain is regulated by resident non-neuronal cells and the blood-brain barrier.1 Dys-regulation of immunosurveillance is a hallmark feature of several diseases2-5 including brain tumors6 that interact with and rely heavily on immune cells,7 suggesting that disrupting the neuroimmunology of tumors could slow their progression. Yet few tools are available to control brain immunology in vivo with local precision, and fewer yet are used for therapeutic intervention. 2 Here, we propose engineered cytokines as a neuroimmune-modulation platform. We demonstrate that the residence time of cytokines in the brain can be tuned by binding them to the extracellular matrix or synthetic scaffolds. We then show that the aluminum hydroxide adjuvant (alum) is retained in the brain >2 weeks. Tethering of inflammatory cytokines such as interleukins (IL) 2 and 12 to alum yields extended neuroinflammation and brain immunosurveillance after intracranial administration, while avoiding systemic toxicity. In mouse models of both immunologically hot and cold brain tumors, the intracranial deposition of alum-tethered cytokines causes significant delay in tumor progression. RNA profiling reveals that engineered cytokines engage both innate and adaptive immunity in the brain. These findings suggest that engineered cytokines can reprogram brain immunosurveillance, informing the development of future therapies for neuroimmune diseases.

bioengineering↗

bioRxiv2021

On-person adaptive evolution of Staphylococcus aureus during atopic dermatitis increases disease severity

Genetic variation among bacterial strains can contribute to heterogeneity in the severity of chronic inflammatory diseases 1,2, but the degree of variation created by de novo mutation during colonization is not well understood. The inflamed skin of people with atopic dermatitis (AD) is frequently colonized with Staphylococcus aureus, an opportunistic pathogen associated with both asymptomatic colonization of nasal passages and invasive disease 3-6. While genetic risk and barrier disruption are critical to AD initiation 7,8, S. aureus colonization is thought to worsen disease severity by promoting skin damage9 1,4,5,10. Here we show, from tracking 23 children treated for AD over 9 months, that S. aureus adapts via de novo mutations during colonization. Patients S. aureus populations are typically dominated by a single lineage, with infrequent invasion by distant lineages. Variants emerge within each lineage with mutation accumulation rates similar to S. aureus in other contexts. Some of these variants replace their ancestors across the body within months, with signatures of adaptive, rather than neutral, forces. Most strikingly, the capsule synthesis gene capD obtained four parallel mutations within one patient and was involved in mutational sweeps in multiple patients. We confirm that selection for capD negativity is common in AD, but not in other contexts, via reanalysis of public S. aureus genomes from 276 people. Our finding of disease-specific selection raises the possibility that adaptation of pathobionts during colonization prolongs the positive feedback cycle of inflammation.

microbiology↗

bioRxiv2020

Allergen-induced dendritic cell migration is controlled through Substance P release by sensory neurons

Dendritic cells (DCs) of the cDC2 lineage are necessary for the initiation of the allergic immune response and in the dermis are marked by their expression of CD301b. CD301b+ dermal DCs respond to allergens encountered in vivo, but not in vitro. This suggests that another cell in the dermis may sense allergens and relay that information to activate and induce the migration of CD301b+ DCs to the draining lymph node. Using a model of cutaneous allergen exposure, we show that allergens directly activate TRPV1+ sensory neurons leading to itch and pain behaviors. Allergen-activated sensory neurons release the neuropeptide Substance P, which stimulates proximally located CD301b+ DCs through MRGPRA1. Substance P induces CD301b+ DC migration to the draining lymph node where they initiate Th2 differentiation. Thus, sensory neurons act as primary sensors of allergens, linking exposure to activation of allergic-skewing DCs and the initiation of the allergic immune response.

immunology↗