J Ethnopharmacol 2025 Jan 30;337(Pt 2):118882.

 doi: 10.1016/j.jep.2024.118882. Epub 2024 Oct 2.

Investigation of the anti-inflammatory, anti-pruritic, and analgesic effects of sophocarpine inhibiting TRP channels in a mouse model of inflammatory itch and pain

Hekun Zeng ¹, Zhe Zhang ², Dan Zhou ³, Ranjing Wang ⁴, Alexei Verkhratsky ⁵, Hong Nie ⁶

• PMID: 39366497
• DOI: 10.1016/j.jep.2024.118882

Abstract

Ethnopharmacological relevance: Sophocarpine is a bioactive compound extracted from the dried root of Sophorae Flavesentis Aiton, a plant that has been used for thousands of years for various conditions including skin itch and pain. Its antipruritic and analgesic effects are suggested in publications, while the molecular mechanisms underneath interacting with TRP channels are not understood.

Aim of the study: We investigated the anti-inflammatory, antipruritic, and analgesic effects of sophocarpine in a murine inflammatory itch and pain model to elucidate the underlying mechanisms.

Materials and methods: We evaluated sophocarpine’s anti-pruritic and analgesic effects by monitoring mice’s scratching and wiping behaviors, and the anti-inflammatory effect by measuring psoriasis area and severity index (PASI) score. The mRNA and protein expression of TRPA1/TRPV1 was analyzed by real-time quantitative polymerase chain reaction and western blotting. We further investigated the relationship between sophocarpine and TRPA1/TRPV1 in mice administered allyl-isothiocyanate (AITC) or capsaicin and by molecular docking.

Results: We found that sophocarpine decreased scratching bouts, wipes, and the PASI score, reduced the TNF-α and IL-1β in the skin and TRPA1 and TRPV1 in the trigeminal ganglion. Pretreatment of sophocarpine decreased AITC-induced scratching bouts and wipes and capsaicin-induced wipes. We also found potential competitive bindings between sophocarpine and AITC/capsaicin to TRPA1/TRPV1.

Conclusions: Sophocarpine is a potential competitive inhibitor of TRPA1 and TRPV1 channels eliciting strong anti-inflammatory, anti-pruritic, and analgesic effects, suggesting its significant therapeutic potential in treating diseases with inflammatory itch and pain.

Keywords: Analgesic; Anti-inflammatory; Anti-pruritic; Sophocarpine; TRPA1; TRPV1.

Sci Adv 2024 Sep 27;10(39):eadp6038. doi: 10.1126/sciadv.adp6038. Epub 2024 Sep 25.

Kappa opioids inhibit spinal output neurons to suppress itch

Tayler D Sheahan ¹, Charles A Warwick ¹, Abby Y Cui ¹, David A A Baranger ², Vijay J Perry ¹, Kelly M Smith ¹, Allison P Manalo ¹, Eileen K Nguyen ¹, H Richard Koerber ¹, Sarah E Ross ^1 3

• PMID: 39321286
• PMCID: PMC11423883
• DOI: 10.1126/sciadv.adp6038

Abstract

Itch is a protective sensation that drives scratching. Although specific cell types have been proposed to underlie itch, the neural basis for itch remains unclear. Here, we used two-photon Ca²⁺ imaging of the dorsal horn to visualize neuronal populations that are activated by itch-inducing agents. We identify a convergent population of spinal interneurons recruited by diverse itch-causing stimuli that represents a subset of neurons that express the gastrin-releasing peptide receptor (GRPR). Moreover, we find that itch is conveyed to the brain via GRPR-expressing spinal output neurons that target the lateral parabrachial nuclei. We then show that the kappa opioid receptor agonist nalfurafine relieves itch by selectively inhibiting GRPR spinoparabrachial neurons. These experiments provide a population-level view of the spinal neurons that respond to pruritic stimuli, pinpoint the output neurons that convey itch to the brain, and identify the cellular target of kappa opioid receptor agonists for the inhibition of itch.

Divergent sensory pathways of sneezing and coughing

Haowu Jiang ¹⁴, Huan Cui ¹⁴, Mengyu Chen ¹, Fengxian Li ¹, Xiaolei Shen ¹, Changxiong J. Guo ¹, George E. Hoekel ¹, Yuyan Zhu ², Liang Han ², Kangyun Wu ³, Michael J. Holtzman ³, Qin Liu ¹⁵

¹Department of Anesthesiology, Washington University Pain Center, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA

²The School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA

³Pulmonary and Critical Care Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA

4These authors contributed equally

https://doi.org/10.1016/j.cell.2024.08.009

Highlights

• Sneezing and coughing are mediated by distinct sensory populations
• Nasal MrgprC11-expressing sensory neurons serve as a core “sneeze” population
• Airway SST-expressing sensory neurons mediate chemically induced cough
• Sneezing and coughing are transmitted and modulated by divergent neuropathways

Summary

Sneezing and coughing are primary symptoms of many respiratory viral infections and allergies. It is generally assumed that sneezing and coughing involve common sensory receptors and molecular neurotransmission mechanisms. Here, we show that the nasal mucosa is innervated by several discrete populations of sensory neurons, but only one population (MrgprC11⁺MrgprA3⁻) mediates sneezing responses to a multitude of nasal irritants, allergens, and viruses. Although this population also innervates the trachea, it does not mediate coughing, as revealed by our newly established cough model. Instead, a distinct sensory population (somatostatin [SST⁺]) mediates coughing but not sneezing, unraveling an unforeseen sensory difference between sneezing and coughing. At the circuit level, sneeze and cough signals are transmitted and modulated by divergent neuropathways. Together, our study reveals the difference in sensory receptors and neurotransmission/modulation mechanisms between sneezing and coughing, offering neuronal drug targets for symptom management in respiratory viral infections and allergies.

Type 2 cytokine-JAK1 signaling is involved in the development of dry-skin induced mechanical alloknesis

Yui Toyosawa ^ab, Eriko Komiya ^ac, Eriko Komiya ^ac, Takahide Kaneko ^b, Yasushi Suga ^b, Mitsutoshi Tominaga^a, Kenji Takamori ^aba

^aJuntendo Itch Research Center (JIRC), Institute for Environmental and Gender- Specific Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Urayasu, Chiba 279-0021, Japan
^bDepartment of Dermatology, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba 279-0021, Japan
^cDepartment of Functional Morphology, Faculty of Pharmacy, Juntendo University, 6-8-1 Hinode, Urayasu, Chiba 279-0013, Japan

Received 8 March 2024, Revised 2 October 2024, Accepted 18 October 2024, Available online 22 October 2024.

Abstract

Background

Mechanical alloknesis (m-alloknesis) is itch hypersensitivity induced by normally innocuous stimuli. It is sometimes observed in dry skin based itch-related diseases such as atopic dermatitis (AD), and often triggers the vicious itch-scratch cycle. The acetone-ether and water (AEW) mouse model mimics dry skin induced m-alloknesis, yet its underlying mechanism remains unclear. Janus kinase (JAK) inhibitors are used to treat AD, but their effects on m-alloknesis are not fully known.

Objective

To reveal the effects of various oral JAK inhibitors on m-alloknesis and their action points, using AEW model.

Methods

AEW model was prepared by treatment with a mixture of acetone-ether, and they were orally administrated a JAK1/2 inhibitor baricitinib, a selective JAK1 inhibitor abrocitinib, or a JAK2 selective inhibitor AZ960, and evaluated m-alloknesis score as the total number of scratching responses in 30 mechanical stimulations. To further elucidate the mechanism of action, IL-4, IL-13 or thymic stromal lymphopoietin (TSLP) or their neutralizing antibodies were also applied to mice. In addition, the levels of these cytokines in mouse skin were measured using multiple immunoassays.

Results

All of JAK inhibitors effectively reduced m-alloknesis, with abrocitinib demonstrating the most significant inhibition. The neutralizing antibodies against IL-4, IL-13, and TSLP inhibited m-alloknesis in AEW mice. Intradermal administration of IL-4, IL-13, or TSLP induced m-alloknesis, and abrocitinib effectively mitigated each cytokine-induced response. Highly sensitive assays detected IL-4, IL-13, IL-31 and TSLP in AEW-treated skin, with TSLP levels significantly increased.

Conclusion

Type 2 cytokine-JAK1 signaling is involved in the development of m-alloknesis in dry skin.

Abbreviations

AD, atopic dermatitis; AEW, acetone-ether and water; IL, interleukin; ILC2, group 2 innate lymphoid cells; JAK, Janus kinase; m-alloknesis, mechanical alloknesis; NT, non-treated; SC, stratum corneum; STAT, signal transducer and activator of transcription; TEWL, transepidermal water loss; Th2, type 2 T helper cells; TSLP, thymic stromal lymphopoietin; W, water

Keywords

atopic dermatitis, dry skin, JAK inhibitors, mechanical alloknesis,mechanical itch, Th2 cytokines

Inhibition of mast cell degranulation by novel small molecule MRGPRX2 antagonists

[The journal of allergy and clinical immunology] July 2, 2024

Background: Mas-related G protein–coupled receptor X2 (MRGPRX2) is a promiscuous receptor on mast cells that mediates IgE-independent degranulation and has been implicated in multiple mast cell–mediated disorders, including chronic urticaria, atopic dermatitis, and pain disorders. Although it is a promising therapeutic target, few potent, selective, small molecule antagonists have been identified, and functional effects of human MRGPRX2 inhibition have not been evaluated in vivo.
Objective: We sought to identify and characterize novel, potent, and selective orally active small molecule MRGPRX2 antagonists for potential treatment of mast cell–mediated disease.

Methods: Antagonists were identified using multiple functional assays in cell lines overexpressing human MRGPRX2, LAD2 mast cells, human peripheral stem cell–derived mast cells, and isolated skin mast cells. Skin mast cell degranulation was evaluated in Mrgprb2em(-/-) knockout and Mrgprb2em(MRGPRX2)
transgenic human MRGPRX2 knock-in mice by assessment of agonist-induced skin vascular permeability. Ex vivo skin mast cell degranulation and associated histamine release was evaluated by microdialysis of human skin tissue samples.

Results: MRGPRX2 antagonists potently inhibited agonist- induced MRGPRX2 activation and mast cell degranulation in all mast cell types tested in an IgE-independent manner. Orally administered MRGPRX2 antagonists also inhibited agonist- induced degranulation and resulting vascular permeability in MRGPRX2 knock-in mice. In addition, antagonist treatment dose dependently inhibited agonist-induced degranulation in ex vivo human skin.

Conclusions: MRGPRX2 small molecule antagonists potently inhibited agonist-induced mast cell degranulation in vitro and in vivo as well as ex vivo in human skin, supporting potential therapeutic utility as a novel treatment for multiple human diseases involving clinically relevant mast cell activation.

Vitexin promotes the anti-senescence effect via inhibiting JAK2/STAT3 in D-Galactose-induced progeria mice and stress-induced premature senescence

Xiaojuan Han ^ab1, Lu Li ^c1, Jiamei Xie ^a, Qing Lei ^a, Yansong Li ^a, Huan Liu ^a, Haoran Sun ^a, Xiaohua Zhang ^a, Xingchun Gou ^ab

https://doi.org/10.1016/j.ejphar.2024.176865

Abstract

Vitexin is a natural flavonoid glycoside compound extracted from the leaves and seeds of Vitex negundo. It is widely distributed in the leaves and stems of numerous plants and exhibites remarkable anti-tumor, anti-inflammatory, and anti-hypertensive properties. However, whether vitexin presents the anti-aging and senescence prevention effect has not been fully elucidated. The purpose of this study is to investigate the effect of vitexin on progeria mice and cellular senescence, as well as its underlying molecular mechanisms. To generate a premature aging/senescence model in vivo and in vitro, we used D-galactose (D-gal), hydrogen peroxide (H₂O₂), and adriamycin (ADR), respectively. Our findings demonstrated that vitexin potentially delays D-gal-induced progeria mice; similar effects were observed in stress-induced premature senescent fibroblasts in culture. Interestingly, this effect of vitexin is closely correlated with the reduction of the senescence-associated secretory phenotype (SASP) and the inhibition of the SASP-related JAK2/STAT3 pathway. Furthermore, we determined that vitexin meets the pharmacological parameters using the freely available ADMET web tool. Collectively, our findings demonstrate that vitexin possesses anti-senescence and anti-aging properties due to the inhibition of SASP and suppression of JAK2/STAT3 signaling pathway.

Nociceptive transient receptor potential ankyrin 1 (TRPA1) in sensory neurons are targets of the antifungal drug econazole

Kaoru Kasuya1, Kenji Takahashi1,2, Miho Hashimoto2 and Toshio Ohta1,2*

Abstract

Background Econazole is a widely used imidazole derivative antifungal for treating skin infections. The molecular

targets for its frequent adverse effects of skin irritation symptoms, such as pruritus, burning sensation, and pain, have

not been clarified. Transient receptor potential (TRP) channels, non-selective cation channels, are mainly expressed in

peripheral sensory neurons and serve as sensors for various irritants.

Methods We investigated the effect of econazole on TRP channel activation by measuring intracellular calcium

concentration ([Ca2+]i) through fluorescent ratio imaging in mouse dorsal root ganglion (DRG) neurons isolated from

wild-type, TRPA1(−/−) and TRPV1(−/−) mice, as well as in heterologously TRP channel-expressed cells. A cheek injection

model was employed to assess econazole-induced itch and pain in vivo.

Results Econazole evoked an increase in [Ca2+]i, which was abolished by the removal of extracellular Ca2+ in mouse

DRG neurons. The [Ca2+]i responses to econazole were suppressed by a TRPA1 blocker but not by a TRPV1 blocker.

Attenuation of the econazole-induced [Ca2+]i responses was observed in the TRPA1(−/−) mouse DRG neurons but was

not significant in the TRPV1(−/−) neurons. Econazole increased the [Ca2+]i in HEK293 cells expressing TRPA1 (TRPA1-

HEK) but not in those expressing TRPV1, although at higher concentrations, it induced Ca2+ mobilization from

intracellular stores in untransfected naïve HEK293 cells. Miconazole, which is a structural analog of econazole, also

increased the [Ca2+]i in mouse DRG neurons and TRPA1-HEK, and its nonspecific action was larger than econazole.

Fluconazole, a triazole drug failed to activate TRPA1 and TRPV1 in mouse DRG neurons and TRPA1-HEK. Econazole

induced itch and pain in wild-type mice, with reduced responses in TRPA1(−/−) mice.

Conclusions These findings suggested that the imidazole derivatives econazole and miconazole may induce skin

irritation by activating nociceptive TRPA1 in the sensory neurons. Suppression of TRPA1 activation may mitigate the

adverse effects of econazole.

Keywords Antifungal, Heterologous expression, Intracellular Ca2+ concentration, Nociceptor, Sensory neuron,

Transient receptor potential channel

Sensory neuronal STAT3 is critical for IL-31 receptor expression and inflammatory itch

Sonoko Takahashi ¹¹³, Sotaro Ochiai ¹¹⁰¹³ Jianshi Jin ²¹¹, Noriko Takahashi ¹, Susumu Toshima ¹³, Harumichi Ishigame ¹¹², Kenji Kabashima ⁴⁵, Masato Kubo ⁶⁷, Manabu Nakayama ⁸, Katsuyuki Shiroguchi ², Takaharu Okada ¹⁹¹⁴

https://doi.org/10.1016/j.celrep.2023.113433

Highlights

• Sensory neuronal IL-31RA and STAT3 are essential for IL-31-induced itch
• STAT3 is important for expression and downstream signaling of IL-31 receptor
• IL-31 enhances GPCR-induced itch transmitted by multiple sensory neuronal subsets
• Sensory neuronal STAT3 contributes to IL-31-independent inflammatory itch

Summary

IL-31 receptor blockade suppresses pruritus of atopic dermatitis. However, cell-type-specific contributions of IL-31 receptor to itch, its expression mechanism, and the downstream signaling pathway to induce itch remain unknown. Here, using conditional knockout mice, we demonstrate that IL-31-induced itch requires sensory neuronal IL-31 receptor and STAT3. We find that IL-31 receptor expression is dependent on STAT3 in sensory neurons. In addition, pharmacological experiments suggest that STAT3 activation is important for the itch-inducing signaling downstream of the IL-31 receptor. A cutaneous IL-31 injection induces the nuclear accumulation of activated STAT3 first in sensory neurons that abundantly express IL-31 receptor and then in other itch-transmitting neurons. IL-31 enhances itch induced by various pruritogens including even chloroquine. Finally, pruritus associated with dermatitis is partially dependent on sensory neuronal IL-31 receptor and strongly on sensory neuronal STAT3. Thus, sensory neuronal STAT3 is essential for IL-31-induced itch and further contributes to IL-31-independent inflammatory itch.

LPS exacerbates TRPV4-mediated itch through the intracellular TLR4-PI3K signalling

Yanping Hao1,2,3 | Liyan Wu1,2 | Yuhui Wang4 | Dongmei Shan1,2 | Yifei Liu1 | Jing Feng1,2 | Yi Chang3 | Ting Wang1,2,5,6

J Cell Mol Med  2024 Jul;28(13):e18509. doi: 10.1111/jcmm.18509.

• ¹Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
• ²University of Chinese Academy of Sciences, Beijing, China.
• ³Yangpu Hospital, School of Medicine, Tongji University, Shanghai, China.
• ⁴Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
• ⁵Yunnan Key Laboratory of Gastrodia and Fungi Symbiotic Biology, Zhaotong University, Zhaotong, Yunnan, China.
• ⁶Yunnan Engineering Research Center of Green Planting and Processing of Gastrodia, Zhaotong University, Zhaotong, Yunnan, China.

PMID: 38957035 PMCID: PMC11220342 DOI: 10.1111/jcmm.18509

Abstract

Pruritus is often accompanied with bacterial infections, but the underlying mechanism is not fully understood. Although previous studies revealed that lipopolysaccharides (LPS) could directly activate TRPV4 channel and TRPV4 is involved in the generation of both acute itch and chronic itch, whether and how LPS affects TRPV4-mediated itch sensation remains unclear. Here, we showed that LPS-mediated TRPV4 sensitization exacerbated GSK101-induced scratching behaviour in mice. Moreover, this effect was compromised in TLR4-knockout mice, suggesting LPS acted through a TLR4-dependent mechanism. Mechanistically, LPS enhanced GSK101-evoked calcium influx in mouse ear skin cells and HEK293T cells transfected with TRPV4. Further, LPS sensitized TRPV4 channel through the intracellular TLR4-PI3K-AKT signalling. In summary, our study found a modulatory role of LPS in TRPV4 function and highlighted the TLR4-TRPV4 interaction in itch signal amplification.

Keywords: LPS; PI3K; TLR4; TRPV4; itch sensitization.

The fungal secretory peptide micasin induces itch by activating MRGPRX1/C11/A1 on peripheral neurons

Haifeng Yang ¹, Yian Chen ², Luyao Wang ², Bing Gan ³, Leiye Yu ³, Ruobing Ren ³, Hang Fai Kwok ⁴, Yingliang Wu ², Zhijian Cao ⁵

J Invest Dermatol. 2024 Jun 28:S0022-202X(24)01871-2.

PMID: 38945438
DOI: 10.1016/j.jid.2024.05.031

Abstract

Pruritus is the leading symptom of dermatophytosis. Microsporium canis is one of the predominant dermatophytes causing dermatophytosis. However, the pruritogenic agents and the related molecular mechanisms of the dermatophyte M. canis remain poorly understood. Here, the secretion of the dermatophyte M. canis was found to dose-dependently evoke itch in mice. The fungal peptide micasin secreted from M. canis was then identified to elicit mouse significant scratching and itching responses. The peptide micasin was further revealed to directly activate mouse dorsal root ganglia (DRG) neurons to mediate the non-histaminergic itch. Knockout and antagonistic experiments demonstrated that MRGPRX1/C11/A1 rather than MRGPRX2/b2 activated by micasin contributed to pruritus. The chimera and mutation of MRGPRX1 showed that three domains (ECL3, TMH3 and TMH6) and four hydrophobic residues (Y99, F237, L240 and W241) of MRGPRX1 played the key role in micasin-triggered MRGPRX1 activation. Our study sheds light on the dermatophytosis-associated pruritus and may provide potential therapeutic targets and strategies against pruritus caused by dermatophytes.

Keywords: Dermatophytosis; Fungal defensin; Itch; Microsporium canis; Mrgprs.