PXL01 alters macrophage response with no effect on axonal outgrowth or Schwann cell response after nerve repair in rats.

Background: Adjunctive pharmacological treatment may improve nerve regeneration. We investigated nerve regeneration processes of PXL01 - a lactoferrin-derived peptide - after repair of the sciatic nerve in healthy Wistar rats. Materials & methods: PXL01, sodium hyaluronate (carrier) or sodium chloride was administered around the repair. After 6 days axonal outgrowth, Schwann cell response, pan- (CD68) and pro-healing (CD206) macrophages in sciatic nerve, sensory neuronal response in dorsal root ganglia (DRG) and expression of heat shock protein 27 (HSP27) in sciatic nerves and DRGs were analyzed. Results: Despite a lower number of pan-macrophages, other investigated variables in sciatic nerves or DRGs did not differ between the treatment groups. Conclusion: PLX01 applied locally inhibits inflammation through pan-macrophages in repaired sciatic nerves without any impact on nerve regeneration or pro-healing macrophages.

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Cellular and axonal transport phenotypes due to the C9ORF72 HRE in iPSC motor and sensory neurons.

Induced pluripotent stem cell (iPSC)-derived motor neurons (MNs) from patients with amyotrophic lateral sclerosis (ALS) and the C9ORF72 hexanucleotide repeat expansion (HRE) have multiple cellular phenotypes, but which of these accurately reflect the biology underlying the cell-specific vulnerability of ALS is uncertain. We therefore compared phenotypes due to the C9ORF72 HRE in MNs with sensory neurons (SNs), which are relatively spared in ALS. The iPSC models were able to partially reproduce the differential gene expression seen between adult SNs and MNs. We demonstrated that the typical hallmarks of C9ORF72-ALS, including RNA foci and dipeptide formation, as well as specific axonal transport defects, occurred equally in MNs and SNs, suggesting that these in vitro phenotypes are not sufficient to explain the cell-type selectivity of ALS in isolation.

Mecp2 Deficiency in Peripheral Sensory Neuron Improves Cognitive Function by Enhancing Hippocampal Dendritic Spine Densities in Mice.

Methyl-CpG-binding protein 2 (Mecp2) is an epigenetic modulator and numerous studies have explored its impact on the central nervous system manifestations. However, little attention has been given to its potential contributions to the peripheral nervous system (PNS). To investigate the regulation of Mecp2 in the PNS on specific central regions, we generated Mecp2fl/flAdvillincre mice with the sensory-neuron-specific deletion of the Mecp2 gene and found the mutant mice had a heightened sensitivity to temperature, which, however, did not affect the sense of motion, social behaviors, and anxiety-like behavior. Notably, in comparison to Mecp2fl/fl mice, Mecp2fl/flAdvillincre mice exhibited improved learning and memory abilities. The levels of hippocampal synaptophysin and PSD95 proteins were higher in Mecp2fl/flAdvillincre mice than in Mecp2fl/fl mice. Golgi staining revealed a significant increase in total spine density, and dendritic arborization in the hippocampal pyramidal neurons of Mecp2fl/flAdvillincre mice compared to Mecp2fl/fl mice. In addition, the activation of the BDNF-TrkB-CREB1 pathway was observed in the hippocampus and spinal cord of Mecp2fl/flAdvillincre mice. Intriguingly, the hippocampal BDNF/CREB1 signaling pathway in mutant mice was initiated within 5 days after birth. Our findings suggest a potential therapeutic strategy targeting the BDNF-TrkB-CREB1 signaling pathway and peripheral somasensory neurons to treat learning and cognitive deficits associated with Mecp2 disorders.

Role of iRhom2 in Olfaction: Implications for Odorant Receptor Regulation and Activity-Dependent Adaptation.

The cell surface metalloprotease ADAM17 (a disintegrin and metalloprotease 17) and its binding partners iRhom2 and iRhom1 (inactive Rhomboid-like proteins 1 and 2) modulate cell-cell interactions by mediating the release of membrane proteins such as TNFα (Tumor necrosis factor α) and EGFR (Epidermal growth factor receptor) ligands from the cell surface. Most cell types express both iRhoms, though myeloid cells exclusively express iRhom2, and iRhom1 is the main iRhom in the mouse brain. Here, we report that iRhom2 is uniquely expressed in olfactory sensory neurons (OSNs), highly specialized cells expressing one olfactory receptor (OR) from a repertoire of more than a thousand OR genes in mice. iRhom2-/- mice had no evident morphological defects in the olfactory epithelium (OE), yet RNAseq analysis revealed differential expression of a small subset of ORs. Notably, while the majority of ORs remain unaffected in iRhom2-/- OE, OSNs expressing ORs that are enriched in iRhom2-/- OE showed fewer gene expression changes upon odor environmental changes than the majority of OSNs. Moreover, we discovered an inverse correlation between the expression of iRhom2 compared to OSN activity genes and that odor exposure negatively regulates iRhom2 expression. Given that ORs are specialized G-protein coupled receptors (GPCRs) and many GPCRs activate iRhom2/ADAM17, we investigated if ORs could activate iRhom2/ADAM17. Activation of an olfactory receptor that is ectopically expressed in keratinocytes (OR2AT4) by its agonist Sandalore leads to ERK1/2 phosphorylation, likely via an iRhom2/ADAM17-dependent pathway. Taken together, these findings point to a mechanism by which odor stimulation of OSNs activates iRhom2/ADAM17 catalytic activity, resulting in downstream transcriptional changes to the OR repertoire and activity genes, and driving a negative feedback loop to downregulate iRhom2 expression.

Odorant receptor co-receptors affect expression of tuning receptors in Drosophila.

Insects detect odorants using two large families of heteromeric receptors, the Odorant Receptors (ORs) and Ionotropic Receptors (IRs). Most OR and IR genes encode odorant-binding "tuning" subunits, whereas four (Orco, Ir8a, Ir25a, and Ir76b) encode co-receptor subunits required for receptor function. Olfactory neurons are thought to degenerate in the absence of Orco in ants and bees, and limited data suggest this may happen to some olfactory neurons in Drosophila fruit flies as well. Here, we thoroughly examined the role of co-receptors on olfactory neuron survival in Drosophila. Leveraging knowledge that olfactory neuron classes are defined by the expression of different tuning receptors, we used tuning receptor expression in antennal transcriptomes as a proxy for the survival of distinct olfactory neuron classes. Consistent with olfactory neuron degeneration, expression of many OR-family tuning receptors is decreased in Orco mutants relative to controls, and transcript loss is progressive with age. The effects of Orco are highly receptor-dependent, with expression of some receptor transcripts nearly eliminated and others unaffected. Surprisingly, further studies revealed that olfactory neuron classes with reduced tuning receptor expression generally survive in Orco mutant flies. Furthermore, there is little apoptosis or neuronal loss in the antenna of these flies. We went on to investigate the effects of IR family co-receptor mutants using similar approaches and found that expression of IR tuning receptors is decreased in the absence of Ir8a and Ir25a, but not Ir76b. As in Orco mutants, Ir8a-dependent olfactory neurons mostly endure despite near-absent expression of associated tuning receptors. Finally, we used differential expression analysis to identify other antennal genes whose expression is changed in IR and OR co-receptor mutants. Taken together, our data indicate that odorant co-receptors are necessary for maintaining expression of many tuning receptors at the mRNA level. Further, most Drosophila olfactory neurons persist in OR and IR co-receptor mutants, suggesting that the impact of co-receptors on neuronal survival may vary across insect species.

Candidate membrane protein gene families related to chemoreception in a wood-boring beetle, Pharsalia antennata Gahan (Coleoptera: Cerambycidae).

The longhorned beetles are key players for the maintenance of biodiversity in the terrestrial ecosystem. As xylophagous cerambycid insects in Coleoptera, the beetles have evolved specialized olfactory and gustatory systems to recognize chemical cues in the surrounding habitats. Despite over 36,000 described species in the Cerambycidae family including a wood-boring pest Pharsalia antennata, only a limited number of them (<1 %) have been characterized regarding their chemical ecology at the molecular level. Here, we surveyed four membrane protein gene families in P. antennata related to chemoreception through transcriptomics, phylogenetics and expression profiling analyses. In total, 144 genes encoding 72 odorant receptors (ORs), 33 gustatory receptors (GRs), 23 ionotropic receptors (IRs), four sensory neuron membrane proteins (SNMPs) and 12 ionotropic glutamate receptors (iGluRs) were harvested from the transcriptome of multiple tissues including antennae and legs of both sexes. The lineage-specific expansion of PantORs possibly implied a diverse range of host plants in this beetle, supporting this correlation between the host range and olfactory receptor repertoire sizes across cerambycid species. Further phylogenetic analysis revealed that Group 2 was contributed mainly to the large OR gene repertoire in P. antennata, representing 18 genes in Group 2A and eight in Group 2B. On the other hand, some key chemosensory genes were identified by applying a phylogenetics approach, such as PantOR21 close to the 2-phenylethanol receptor in Megacyllene caryae, three carbon dioxide GRs and seven Antennal IRs (A-IRs) clades. We also determined sex- and tissue-specific expression profiles of 69 chemosensory genes, revealing the high expression of most PantORs in antennae. Noticeably, 10 sex-biased genes (six PantORs, three PantIRs and PantSNMP1a) were presented in antennae, five sex-biased PantGRs in legs and 39 sex-biased genes (15 PantORs, 13 PantGRs, eight PantIRs and three PantSNMPs) in abdomens. These findings have greatly enhanced our knowledge about the chemical ecology of P. antennata and identify candidate molecular targets for mediating smell and taste of this beetle.

Neuron-specific RNA-sequencing reveals different responses in peripheral neurons after nerve injury.

Peripheral neurons are heterogeneous and functionally diverse, but all share the capability to switch to a pro-regenerative state after nerve injury. Despite the assumption that the injury response is similar among neuronal subtypes, functional recovery may differ. Understanding the distinct intrinsic regenerative properties between neurons may help to improve the quality of regeneration, prioritizing the growth of axon subpopulations to their targets. Here, we present a comparative analysis of regeneration across four key peripheral neuron populations: motoneurons, proprioceptors, cutaneous mechanoreceptors, and nociceptors. Using Cre/Ai9 mice that allow fluorescent labeling of neuronal subtypes, we found that nociceptors showed the greater regeneration after a sciatic crush, followed by motoneurons, mechanoreceptors, and, finally, proprioceptors. By breeding these Cre mice with Ribotag mice, we isolated specific translatomes and defined the regenerative response of these neuronal subtypes after axotomy. Only 20% of the regulated genes were common, revealing a diverse response to injury among neurons, which was also supported by the differential influence of neurotrophins among neuron subtypes. Among differentially regulated genes, we proposed MED12 as a specific regulator of the regeneration of proprioceptors. Altogether, we demonstrate that the intrinsic regenerative capacity differs between peripheral neuron subtypes, opening the door to selectively modulate these responses.

Cholesterol-dependent LXR transcription factor activity represses pronociceptive effects of estrogen in sensory neurons and pain induced by myelin basic protein fragments.

Background: A bioactive myelin basic protein (MBP) fragment, comprising MBP84-104, is released in sciatic nerve after chronic constriction injury (CCI). Intraneural injection (IN) of MBP84-104 in an intact sciatic nerve is sufficient to induce persistent neuropathic pain-like behavior via robust transcriptional remodeling at the injection site and ipsilateral dorsal root ganglia (DRG) and spinal cord. The sex (female)-specific pronociceptive activity of MBP84-104 associates with sex-specific changes in cholesterol metabolism and activation of estrogen receptor (ESR)1 signaling. Methods: In male and female normal and post-CCI rat sciatic nerves, we assessed: (i) cholesterol precursor and metabolite levels by lipidomics; (ii) MBP84-104 interactors by mass spectrometry of MBP84-104 pull-down; and (iii) liver X receptor (LXR)α protein expression by immunoblotting. To test the effect of LXRα stimulation on IN MBP84-104-induced mechanical hypersensitivity, the LXRα expression was confirmed along the segmental neuraxis, in DRG and spinal cord, followed by von Frey testing of the effect of intrathecally administered synthetic LXR agonist, GW3965. In cultured male and female rat DRGs exposed to MBP84-104 and/or estrogen treatments, transcriptional effect of LXR stimulation by GW3965 was assessed on downstream cholesterol transporter Abc, interleukin (IL)-6, and pronociceptive Cacna2d1 gene expression. Results: CCI regulated LXRα ligand and receptor levels in nerves of both sexes, with cholesterol precursors, desmosterol and 7-DHC, and oxysterol elevated in females relative to males. MBP84-104 interacted with nuclear receptor coactivator (Ncoa)1, known to activate LXRα, injury-specific in nerves of both sexes. LXR stimulation suppressed ESR1-induced IL-6 and Cacna2d1 expression in cultured DRGs of both sexes and attenuated MBP84-104-induced pain in females. Conclusion: The injury-released bioactive MBP fragments induce pronociceptive changes by selective inactivation of nuclear transcription factors, including LXRα. By Ncoa1 sequestration, bioactive MBP fragments render LXRα function to counteract pronociceptive activity of estrogen/ESR1 in sensory neurons. This effect of MBP fragments is prevalent in females due to high circulating estrogen levels in females relative to males. Restoring LXR activity presents a promising therapeutic strategy in management of neuropathic pain induced by bioactive MBP.

Satellite Glial Cells in Human Disease.

Satellite glial cells (SGCs) are the main type of glial cells in sensory ganglia. Animal studies have shown that these cells play essential roles in both normal and disease states. In a large number of pain models, SGCs were activated and contributed to the pain behavior. Much less is known about SGCs in humans, but there is emerging recognition that SGCs in humans are altered in a variety of clinical states. The available data show that human SGCs share some essential features with SGCs in rodents, but many differences do exist. SGCs in DRG from patients suffering from common painful diseases, such as rheumatoid arthritis and fibromyalgia, may contribute to the pain phenotype. It was found that immunoglobulins G (IgG) from fibromyalgia patients can induce pain-like behavior in mice. Moreover, these IgGs bind preferentially to SGCs and activate them, which can sensitize the sensory neurons, causing nociception. In other human diseases, the evidence is not as direct as in fibromyalgia, but it has been found that an antibody from a patient with rheumatoid arthritis binds to mouse SGCs, which leads to the release of pronociceptive factors from them. Herpes zoster is another painful disease, and it appears that the zoster virus resides in SGCs, which acquire an abnormal morphology and may participate in the infection and pain generation. More work needs to be undertaken on SGCs in humans, and this review points to several promising avenues for better understanding disease mechanisms and developing effective pain therapies.

Pathophysiological Roles of Ion Channels in Epidermal Cells, Immune Cells, and Sensory Neurons in Psoriasis.

Psoriasis is a chronic inflammatory skin disease characterized by the rapid abnormal growth of skin cells in the epidermis, driven by an overactive immune system. Consequently, a complex interplay among epidermal cells, immune cells, and sensory neurons contributes to the development and progression of psoriasis. In these cellular contexts, various ion channels, such as acetylcholine receptors, TRP channels, Ca2+ release-activated channels, chloride channels, and potassium channels, each serve specific functions to maintain the homeostasis of the skin. The dysregulation of ion channels plays a major role in the pathophysiology of psoriasis, affecting various aspects of epidermal cells, immune responses, and sensory neuron signaling. Impaired function of ion channels can lead to altered calcium signaling, inflammation, proliferation, and sensory signaling, all of which are central features of psoriasis. This overview summarizes the pathophysiological roles of ion channels in epidermal cells, immune cells, and sensory neurons during early and late psoriatic processes, thereby contributing to a deeper understanding of ion channel involvement in the interplay of psoriasis and making a crucial advance toward more precise and personalized approaches for psoriasis treatment.

Cholinergic Receptor Muscarinic 1 Co-Localized with Mitochondria in Cultured Dorsal Root Ganglion Neurons, and Its Deletion Disrupted Mitochondrial Ultrastructure in Peripheral Neurons: Implications in Alzheimer's Disease.

Background: Loss of Cholinergic Receptor Muscarinic 1 (CHRM1) has been linked to the pathogenesis of Alzheimer's disease (AD). Our recent study found significantly lower CHRM1 protein levels in AD patient cortices, linked to reduced survival. Furthermore, using knockout mice (Chrm1-/-) we demonstrated that deletion of Chrm1 alters cortical mitochondrial structure and function, directly establishing a connection between its loss and mitochondrial dysfunction in the context of AD. While CHRM1's role in the brain has been extensively investigated, its impact on peripheral neurons in AD remains a crucial area of research, especially considering reported declines in peripheral nerve conduction among AD patients. Objective: The objective was to characterize Chrm1 localization and mitochondrial deficits in Chrm1-/- dorsal root ganglion (DRG) neurons. Methods: Recombinant proteins tagged with Green or Red Fluorescent Protein (GFP/RFP) were transiently expressed to investigate the localization of Chrm1 and mitochondria, as well as mitochondrial movement in the neurites of cultured primary mouse DRG neurons, using confocal time-lapse live cell imaging. Transmission electron microscopy was performed to examine the ultrastructure of mitochondria in both wild-type and Chrm1-/- DRGs. Results: Fluorescence imaging revealed colocalization and comigration of N-terminal GFP-tagged Chrm1 and mitochondrial localization signal peptide-tagged RFP-labelled mitochondria in the DRGs neurons. A spectrum of mitochondrial structural abnormalities, including disruption and loss of cristae was observed in 87% neurons in Chrm1-/- DRGs. Conclusions: This study suggests that Chrm1 may be localized in the neuronal mitochondria and loss of Chrm1 in peripheral neurons causes sever mitochondrial structural aberrations resembling AD pathology.

Combined effect of Neurotropin® and methylcobalamin on postherpetic neuralgia in mice infected with herpes simplex virus type-1.

BACKGROUND: Postherpetic pain (PHP) is difficult to control. Although Neurotropin® (NTP) and methylcobalamin (MCB) are often prescribed to treat the pain, the efficacy of combined treatment for PHP remains imcompletely understood. OBJECTIVE: In this study, we investigate the combined effects of NTP and MCB on PHP in mice. METHODS: NTP and MCB were administered from day 10-29 after herpes simplex virus type-1 (HSV-1) infection. The pain-related responses were evaluated using a paint brush. The expression of neuropathy-related factor (ATF3) and nerve repair factors (GAP-43 and SPRR1A) in the dorsal root ganglion (DRG) and neurons in the skin were evaluated by immunohistochemical staining. Nerve growth factor (NGF) and neurotrophin-3 (NT3) mRNA expression levels were evaluated using real-time PCR. RESULTS: Repeated treatment with NTP and MCB after the acute phase inhibited PHP. Combined treatment with these drugs inhibited PHP at an earlier stage than either treatment alone. In the DRG of HSV-1-infected mice, MCB, but not NTP, decreased the number of cells expressing ATF3 and increased the number of cells expressing GAP-43- and SPRR1A. In addition, MCB, but not NTP, also increased and recovered non-myelinated neurons decreased in the lesional skin. NTP increased the mRNA levels of NTF3 in keratinocytes, while MCB increased that of NGF in Schwann cells. CONCLUSION: These results suggest that combined treatment with NTP and MCB is useful for the treatment of PHP. The combined effect may be attributed to the different analgesic mechanisms of these drugs.

The protective barrier role of satellite glial cells in sensory ganglia.

Neurons in sensory ganglia are wrapped completely by satellite glial cells (SGCs). One putative function of SGCs is to regulate the neuronal microenvironment, but this role has received only little attention. In this study we investigated whether the SGC envelope serves a barrier function and how SGCs may control the neuronal microenvironment. We studied this question on short-term (<24 h) cell cultures of dorsal root ganglia and trigeminal ganglia from adult mice, which contain neurons surrounded with SGCs, and neurons that are not. Using calcium imaging, we measured neuronal responses to molecules with established actions on sensory neurons. We found that neurons surrounded by SGCs had a smaller response to molecules such as adenosine triphosphate (ATP), glutamate, GABA, and bradykinin than neurons without glial cover. When we inhibited the activity of NTPDases, which hydrolyze the ATP, and also when we inhibited the glutamate and GABA transporters on SGCs, this difference in the neuronal response was no longer observed. We conclude that the SGC envelope does not hinder diffusional passage, but acts as a metabolic barrier that regulates the neuronal microenvironment, and can protect the neurons and modulate their activity.

Stimulatory effect of methylglyoxal on capsaicin-sensitive lung vagal afferents in rats: role of TRPA1.

Methylglyoxal (MG), a reactive metabolic byproduct of glycolysis, is a causative of painful diabetic neuropathy. Patients with diabetes are associated with more frequent severe asthma exacerbation. Stimulation of capsaicin-sensitive lung vagal (CSLV) afferents may contribute to the pathogenesis of hyperreactive airway diseases such as asthma. However, the possibility of the stimulatory effect of MG on CSLV afferents and the underlying mechanisms remain unknown. Our results showed that intravenous injection of MG (25 mg/kg, MG25) in anesthetized, spontaneously breathing rats elicited pulmonary chemoreflexes characterized by apnea, bradycardia, and hypotension. The MG-induced apneic response was reproducible and dose dependent. MG25 no longer evoked these reflex responses after perineural capsaicin treatment of both cervical vagi to block C-fibers' conduction, suggesting that the reflexes were mediated through the stimulation of CSLV afferents. Pretreatment with HC030031 [an antagonist of transient receptor potential ankyrin subtype 1 protein (TRPA1)] or AP18 (another TRPA1 antagonist), but not their vehicle, markedly attenuated the apneic response induced by MG25. Consistently, electrophysiological results showed that pretreatment with HC030031 largely attenuated the intense discharge in CSLV afferents induced by injection of MG25 in open-chest and artificially ventilated rats. In isolated CSLV neurons, the perfusion of MG evoked an abrupt and pronounced increase in calcium transients in a concentration-dependent manner. This stimulatory effect on CSLV neurons was also abolished by HC030031 treatment but not by its vehicle. In conclusion, these results suggest that MG exerts a stimulatory effect on CSLV afferents, inducing pulmonary chemoreflexes, and such stimulation is mediated through the TRPA1 activation.NEW & NOTEWORTHY Methylglyoxal (MG) is implicated in the development of painful diabetic neuropathy. A retrospective cohort study revealed an increased incidence of asthma exacerbations in patients with diabetes. This study demonstrated that elevated circulating MG levels stimulate capsaicin-sensitive lung vagal afferents via activation of TRPA1, which in turn triggers respiratory reflexes. These findings provide new information for understanding the pathogenic mechanism of diabetes-associated hyperreactive airway diseases and potential therapy.

Interactions between skin-resident dendritic and Langerhans cells and pain-sensing neurons.

Various immune cells in the skin contribute to its function as a first line of defense against infection and disease, and the skin's dense innervation by pain-sensing sensory neurons protects the host against injury or damage signals. Dendritic cells (DCs) are a heterogeneous population of cells that link the innate immune response to the adaptive response by capturing, processing, and presenting antigens to promote T-cell differentiation and activation. DCs are abundant across peripheral tissues, including the skin, where they are found in the dermis and epidermis. Langerhans cells (LCs) are a DC subset located only in the epidermis; both populations of cells can migrate to lymph nodes to contribute to broad immune responses. Dermal DCs and LCs are found in close apposition with sensory nerve fibers in the skin and express neurotransmitter receptors, allowing them to communicate directly with the peripheral nervous system. Thus, neuroimmune signaling between DCs and/or LCs and sensory neurons can modulate physiologic and pathophysiologic pathways, including immune cell regulation, host defense, allergic response, homeostasis, and wound repair. Here, we summarize the latest discoveries on DC- and LC-neuron interaction with neurons while providing an overview of gaps and areas not previously explored. Understanding the interactions between these 2 defence systems may provide key insight into developing therapeutic targets for treating diseases such as psoriasis, neuropathic pain, and lupus.

Murine model of eosinophilic chronic rhinosinusitis with nasal polyposis inducing neuroinflammation and olfactory dysfunction.

BACKGROUND: Chronic rhinosinusitis (CRS) is a common inflammatory condition affecting the nasal and paranasal sinus mucosa, often accompanied by olfactory dysfunction. Eosinophilic CRS with nasal polyps (ECRSwNP) is a subtype of CRS characterized by eosinophilic infiltration. Animal models for ECRSwNP with olfactory dysfunction are necessary for exploring potential therapeutic strategies. OBJECTIVE: The aim of this study was to establish a mouse model of ECRSwNP combined with olfactory dysfunction in a shorter time frame using intranasal ovalbumin and Aspergillus protease (AP) administration. The efficacy of the model was validated by evaluating sinonasal inflammation, cytokine levels, olfactory function, and neuroinflammation in the olfactory bulb. METHODS: Male BALB/c mice were intranasally administered ovalbumin and AP for 6 and 12 weeks to induce ECRSwNP. The resultant ECRSwNP mouse model underwent histologic assessment, cytokine analysis of nasal lavage fluid, olfactory behavioral tests, and gene expression profiling to identify neuroinflammatory markers within the olfactory bulb. RESULTS: The developed mouse model exhibited substantial eosinophil infiltration, increased levels of inflammatory cytokines in nasal lavage fluid, and confirmed olfactory dysfunction through behavioral assays. Furthermore, olfactory bulb inflammation and reduced mature olfactory sensory neurons were observed in the model. CONCLUSION: This study successfully established a validated mouse model of ECRSwNP with olfactory dysfunction within a remarkably short span of 6 weeks, providing a valuable tool for investigating the pathogenesis and potential therapies for this condition. The model offers an efficient approach for future research in CRS with nasal polyps and olfactory dysfunction.

Sonic hedgehog restrains the ubiquitin-dependent degradation of SP1 to inhibit neuronal/glial senescence associated phenotypes in chemotherapy-induced peripheral neuropathy via the TRIM25-CXCL13 axis.

INTRODUCTION: Chemotherapy-induced peripheral neuropathy (CIPN) is a common complication that affects an increasing number of cancer survivors. However, the current treatment options for CIPN are limited. Paclitaxel (PTX) is a widely used chemotherapeutic drug that induces senescence in cancer cells. While previous studies have demonstrated that Sonic hedgehog (Shh) can counteract cellular dysfunction during aging, its role in CIPN remains unknown. OBJECTIVES: Herein, the aim of this study was to investigate whether Shh activation could inhibits neuronal/glial senescence and alleviates CIPN. METHODS: We treated ND7/23 neuronal cells and RSC96 Schwann cells with two selective Shh activators (purmorphamine [PUR] and smoothened agonist [SAG]) in the presence of PTX. Additionally, we utilized a CIPN mouse model induced by PTX injection. To assess cellular senescence, we performed a senescence-associated ß-galactosidase (SA-ß-gal) assay, measured reactive oxygen species (ROS) levels, and examined the expression of P16, P21, and γH2AX. To understand the underlying mechanisms, we conducted ubiquitin assays, LC-MS/MS, H&E staining, and assessed protein expression through Western blotting and immunofluorescence staining. RESULTS: In vitro, we observed that Shh activation significantly alleviated the senescence-related decline in multiple functions included SA-ß-gal activity, expression of P16 and P21, cell viability, and ROS accumulation in DRG sensory neurons and Schwann cells after PTX exposure. Furthermore, our in vivo experiments demonstrated that Shh activation significantly reduced axonal degeneration, demyelination, and improved nerve conduction. Mechanistically, we discovered that PTX reduced the protein level of SP1, which was ubiquitinated by the E3 ligase TRIM25 at the lysine 694 (K694), leading to increased CXCL13 expression, and we found that Shh activation inhibited PTX-induced neuronal/glial senescence and CIPN through the TRIM25-SP1-CXCL13 axis. CONCLUSION: These findings provide evidence for the role of PTX-induced senescence in DRG sensory neurons and Schwann cells, suggesting that Shh could be a potential therapeutic target for CIPN.

An expanded neurogenetic toolkit to decode olfaction in the African malaria mosquito Anopheles gambiae.

Anopheles gambiae uses its sense of smell to hunt humans. We report a two-step method yielding cell-type-specific driver lines for enhanced neuroanatomical and functional studies of its olfactory system. We first integrated a driver-responder-marker (DRM) system cassette consisting of a linked T2A-QF2 driver, QUAS-GFP responder, and a gut-specific transgenesis marker into four chemoreceptor genes (Ir25a, Ir76b, Gr22, and orco) using CRISPR-Cas9-mediated homology-directed repair. The DRM system facilitated rapid selection of in-frame integrations via screening for GFP+ olfactory sensory neurons (OSNs) in G1 larval progeny, even at genomic loci such as orco where we found the transgenesis marker was not visible. Next, we converted these DRM integrations into T2A-QF2 driver-marker lines by Cre-loxP excision of the GFP responder, making them suitable for binary use in transcuticular calcium imaging. These cell-type-specific driver lines tiling key OSN subsets will support systematic efforts to decode olfaction in this prolific malaria vector.

Exploration for Blood Biomarkers of Human Long Non-coding RNAs Predicting Oxaliplatin-Induced Chronic Neuropathy Through iPS Cell-Derived Sensory Neuron Analysis.

Oxaliplatin, a platinum-based chemotherapeutic agent, frequently causes acute and chronic peripheral sensory neuropathy, for which no effective treatment has been established. In particular, chronic neuropathy can persist for years even after treatment completion, thus worsening patients' quality of life. To avoid the development of intractable adverse effects, a predictive biomarker early in treatment is awaited. In this study, we explored extracellular long non-coding RNAs (lncRNAs) released from primary sensory neurons as biomarker candidates for oxaliplatin-induced peripheral neuropathy. Because many human-specific lncRNA genes exist, we induced peripheral sensory neurons from human induced pluripotent stem cells. Oxaliplatin treatment changed the levels of many lncRNAs in extracellular vesicles (EVs) released from cultured primary sensory neurons. Among them, the levels of release of lncRNAs that were considered to be selectively expressed in dorsal root ganglia were correlated with those of lncRNAs in plasma EV obtained from healthy individuals. Several lncRNAs in plasma EVs early after the initiation of treatment showed greater changes in patients who did not develop chronic neuropathy that persisted for more than 1 year than in those who did. Therefore, these extracellular lncRNAs in plasma EVs may represent predictive biomarkers for the development of chronic peripheral neuropathy induced by oxaliplatin.

Mast cell-sensory neuron crosstalk in allergic diseases.

Mast cells (MCs) are tissue-resident immune cells, well-positioned at the host-environment interface for detecting external antigens and playing a critical role in mobilizing innate and adaptive immune responses. Sensory neurons are afferent neurons innervating most areas of the body but especially in the periphery, where they sense external and internal signals and relay information to the brain. The significance of MC-sensory neuron communication is now increasingly becoming recognized, especially because both cell types are in close physical proximity at the host-environment interface and around major organs of the body and produce specific mediators that can activate each other. In this review, we explore the roles of MC-sensory neuron crosstalk in allergic diseases, shedding light on how activated MCs trigger sensory neurons to initiate signaling in pruritus, shock, and potentially abdominal pain in allergy, and how activated sensory neurons regulate MCs in homeostasis and atopic dermatitis associated with contact hypersensitivity and type 2 inflammation. Throughout the review, we also discuss how these 2 sentinel cell types signal each other, potentially resulting in a positive feedback loop that can sustain inflammation. Unraveling the mysteries of MC-sensory neuron crosstalk is likely to unveil their critical roles in various disease conditions and enable the development of new therapeutic approaches to combat these maladies.