Cimifugin relieves pruritus in psoriasis by inhibiting TRPV4

Published in:- Cell Calcium

JinjinYan^aFanYe^aYingJu^aDijunWang^aJiaoChen^bcXinyuZhang^aZhiYin^dChangmingWang^aYanYang^aChanZhu^aYuanZhou^aPengCao^bcYangXu^dGuangYu^aZongxiangTang^a

DOI: https://doi.org/10.1016/j.ceca.2021.102429

Psoriasis is an immune-mediated chronic inflammatory skin disease characterized by erythema, scales, and infiltration of the skin, which causes deleterious effects on patient quality of life. TRP channel played important roles in the generation and conductance of itch signal . According to our results, psoriasis induced itch was TRPV4 dependent, and TRPV4 expression in both epidermis and DRG were up-regulated in psoriasis. Thus, TRPV4 is an attractive candidate for treating psoriasis induced itch. Cimifugin is a common compound in antipruritic Chinese medicine. In our study, GSK1016790A, a TRPV4 channel specific agonist, induced acute itch was inhibited by cimifugin in a dose-dependent manner. Furthermore, cimifugin treatment reduced the scratching behavior and reversed the TRPV4 up-regulation induced by psoriasis. In particular, cimifugin decreased GSK1016790A induced calcium response both in HaCaT cells and DRG neurons. Importantly, in TRPV4 transfected HEK293 cells, GSK101 induced calcium response was also significantly inhibited by cimifugin pretreatment. Consistent with our calcium imaging result, cimifugin pretreatment also inhibited GSK101 induced inward currents. Our study delineated a new role of TRPV4 in psoriasis and emphasized the antipruritic effect of cimifugin, which opened a new avenue to itch management in psoriasis.

Keyword: Psoriasis, Trpv4, Itch, Cimifugin

J Invest Dermatol. 2021 Apr 1;S0022-202X(21)01129-5. doi: 10.1016/j.jid.2021.03.015.Online ahead of print.

Mechanisms of broad-band ultraviolet B irradiation-induced itch in mice

Liang Cao ¹, Xueping Yue ¹, Yonghui Zhao ¹, Lixia Du ¹, Zili Xie ¹, Yi Yuan ¹, Sha Zhang ², Feng Li ², Jing Feng ³, Hongzhen Hu ¹

• PMID: 33812858
• DOI: 10.1016/j.jid.2021.03.015

Abstract

Although sunburn can produce severe uncontrollable itching, the underlying mechanisms of ultraviolet (UV) irradiation-induced itch are poorly understood because of a lack of experimental animal models of sunburn itch. Here we established a sunburn-related mouse model and found that Broad-band UVB (BB-UVB) irradiation elicited scratching but not wiping behavior in mice. By using a combination of live-cell Ca²⁺ imaging and quantitative RT-PCR on dorsal root ganglion (DRG) neurons, hematoxylin and eosin staining, immunofluorescence staining of skin preparations, behavioral testing, in combination with genetic and pharmacological approaches, we showed that TRPV1-positive DRG neurons but not mast cells are involved in BB-UVB irradiation-induced itch. Moreover, both genetic and pharmacological inhibition of TRPV1 function significantly alleviated BB-UVB irradiation-induced itch response. Collectively, our results suggest that BB-UVB irradiation evokes itch sensation in mice through promoting TRPV1 channel function in DRG neurons and provide potential therapeutic targets for sunburn-related itch.

Keywords: BB-UVB; Itch model; Sunburn-related itch; TRPV1.

The CysLT2R receptor mediates leukotriene C4-driven acute and chronic itch

ABSTRACT

Acute and chronic itch are burdensome manifestations of skinpathologies including allergic skin diseases and atopic dermatitis,but the underlying molecular mechanisms are not well understood.Cysteinyl leukotrienes (CysLTs), comprising LTC4,LTD4, and LTE4,areproduced by immune cells during type 2 inflammation. Here, weuncover a role for LTC4and its signaling through the CysLT receptor2 (CysLT2R) in itch.Cysltr2transcript is highly expressed in dorsalroot ganglia (DRG) neurons linked to itch in mice. We also detectedCYSLTR2in a broad population of human DRG neurons. Injection ofleukotriene C4(LTC4) or its nonhydrolyzable form NMLTC4,butnei-ther LTD4nor LTE4, induced dose-dependent itch but not pain be-haviors in mice. LTC4-mediated itch differed in bout duration andkinetics from pruritogens histamine, compound 48/80, and chloro-quine. NMLTC4-induced itch was abrogated in mice deficient forCysltr2or when deficiency was restricted to radioresistant cells. Itchwas unaffected in mice deficient forCysltr1,Trpv1, or mast cells(WShmice). CysLT2R played a role in itch in the MC903 mouse modelof chronic itch and dermatitis, but not in models of dry skin or com-pound 48/80- orAlternaria-induced itch. In MC903-treated mice,CysLT levels increased in skin over time, andCysltr2−/−mice showeddecreased itch in the chronic phase of inflammation. Collectively,our study reveals that LTC4acts through CysLT2R as its physiologicalreceptor to induce itch, and CysLT2R contributes to itch in a model ofdermatitis. Therefore, targeting CysLT signaling may be a promisingapproach to treat inflammatory itch.

Keywords: itch, neuroimmune, atopic dermatitis, skin, inflammation

A Group of Cationic Amphiphilic Drugs Activates MRGPRX2 and Induces Scratching Behavior in Mice

Katharina Wolf, PhD#*a , Helen Kühn, PhD#a , Felicitas Boehm, MSca , Lisa Gebhardt, MSca , Markus Glaudo, MSc , Konstantin Agelopoulos, PhDb , Sonja Ständer, MDb , Philipp Ectors, PhDc , Dirk Zahn, PhDc , Yvonne K. Riedel, MScd , Dominik Thimm, PhDd , Christa E. Müller, PhDd , Sascha Kretschmann, PhDe , Anita N. Kremer, MD, PhDe , Daphne Chienf, BSc, Nathachit Limjunyawongf , PhD, Qi Pengf , Xinzhong Dong, PhDf , Pavel Kolkhir, MDg,h , Jörg Scheffel, PhDh , Mia Lykke Søgaard, MSca , Benno Weigmann, PhDa , Markus F. Neurath, MDa,i, Tomasz Hawro, MD, PhDh , Martin Metz, MDh , Michael J.M. Fischer, MDj , Andreas E. Kremer, MD, PhD*a

ABSTRACT

Background: Mas gene-related G protein-coupled receptors (MRGPRs) are a GPCR family responsive to various exogenous and endogenous agonists, playing a fundamental role in pain and itch sensation. The primate-specific family member MRGPRX2 and its murine orthologue MRGPRB2 are expressed by mast cells, mediating IgE-independent signaling and pseudo-allergic drug reactions. Objectives: Therefore, knowledge about the function and regulation of MRGPRX2/MRGPRB2 is of major importance in prevention of drug hypersensitivity reactions and drug-induced pruritus.

Methods: To identify novel MRGPR (ant)agonists, we screened a library of pharmacologically active compounds utilizing a high-throughput calcium mobilization assay. Identified hit compounds were analyzed for their pseudo-allergic and pruritogenic effects in mice and human.

Results: We found a class of commonly used drugs activating MRGPRX2 which consists to a large extent of antidepressants, antiallergic drugs, and antipsychotics. Three-dimensional pharmacophore modeling revealed structural similarities of the identified agonists, classifying them as cationic amphiphilic drugs. Mast cell activation was investigated using the three representatively selected antidepressants clomipramine, paroxetine, and desipramine. Indeed, we could show a concentration-dependent activation and MRGPRX2-dependent degranulation of the human mast cell line LAD2. Furthermore, clomipramine, paroxetine, and desipramine were able to induce degranulation of human skin and murine peritoneal mast cells. These substances elicited dose-dependent scratching behavior upon intradermal injection in C57BL/6 mice but less in MRGPRB2-mutant mice as well as wheal-and-flare reactions upon intradermal injections in humans.

Conclusion: Our results contribute to the characterization of structure-activity relationships and functionality of MRGPRX2 ligands and facilitate prediction of adverse reactions like drug induced pruritus to prevent severe drug hypersensitivity reactions.

Abstract

Itch is an evolutionarily conserved sensation that facilitates expulsion of pathogens and noxious stimuli from the skin. However, in organ failure, cancer, and chronic inflammatory disorders such as atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. In addition to chronic itch, patients often experience intense acute itch exacerbations. Recent discoveries have unearthed the neuroimmune circuitry of itch, leading to the development of anti-itch treatments. However, mechanisms underlying acute itch exacerbations remain overlooked. Herein, we identify that a large proportion of patients with AD harbor allergen-specific immunoglobulin E (IgE) and exhibit a propensity for acute itch flares. In mice, while allergen-provoked acute itch is mediated by the mast cell-histamine axis in steady state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene (LT) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a basophil-neuronal circuit that may underlie a variety of neuroimmune processes.

Abstract

Background: Tick bites severely threaten human health because they allow the transmission of many deadly pathogens, including viruses, bacteria, protozoa and helminths. Pruritus is a leading symptom of tick bites, but its molecular and neural bases remain elusive.

Objective: To discover potent drugs and targets for the specific prevention and treatment of tick bite-induced pruritus and arthropod-related itch. Methods We used live-cell calcium imaging, patch-clamp recordings, and genetic ablation and evaluated mouse behavior to investigate the molecular and neural bases of tick bite-induced pruritus.

Results: We found that two tick salivary peptides, IPDef1 and IRDef2, induced itch in mice. IPDef1 was further revealed to have a stronger pruritogenic potential than IRDef2 and to induce pruritus in a histamine-independent manner. IPDef1 evoked itch by activating mouse MrgprC11 and human MrgprX1 on dorsal root ganglion (DRG) neurons. IPDef1-activated MrgprC11/X1 signaling sensitized downstream ion channel TRPV1 on DRG neurons. Moreover, IPDef1 also activated mouse MrgprB2 and its ortholog human MrgprX2 selectively expressed on mast cells, inducing the release of inflammatory cytokines and driving acute inflammation in mice, although mast cell activation did not contribute to IP-O-induced itch. Conclusion Our study identifies tick salivary peptides as a new class of pruritogens that initiate itch through MrgprC11/X1-TRPV1 signaling in pruritoceptors. Our work will provide potential drug targets for the prevention and treatment of pruritus induced by the bites or stings of tick and maybe other arthropods.

Key words: Tick; Peptide; Itch; Mrgprs; TRP channel

GRPR/Extracellular SignaleRegulated Kinase and NPRA/Extracellular SignaleRegulated Kinase Signaling Pathways Play a Critical Role in Spinal Transmission of Chronic Itch

Abstract

Intractable or recurrent chronic itch greatly reduces the patients’ QOL and impairs their daily activities. In this study, we investigated whether there are certain key signaling molecules downstream of the recently identified peptides mediating itch in the spinal cord. RNA sequencing analysis of mouse spinal cord in chronic itch models induced by squaric acid dibutylester and imiquimod showed that extracellular signaleregulated kinase (ERK) 1/2 cascade is the most significantly upregulated gene cluster in both models. In four different mouse models of chronic itch, sustained ERK phosphorylation was detected mainly in spinal neurons, and MAPK/ERK kinase inhibitors significantly inhibited chronic itch in these models. Phosphorylated ERK was observed in the interneurons expressing the receptors of different neuropeptides for itch, including gastrin-releasing peptide receptor, natriuretic peptide receptor A, neuromedin B receptor, and sst2A. Blocking gastrin-releasing peptide receptor and natriuretic peptide receptor A by genetic approaches or toxins in mice significantly attenuated or ablated spinal phosphorylated ERK. When human embryonic kidney 293T cells transfected with these receptors were exposed to their respective agonists, ERK was the most significantly activated intracellular signaling molecule. Together, our work showed that phosphorylated ERK is a unique marker for itch signal transmission in the spinal cord and an attractive target for the treatment of chronic itch.

FGF13 is required for histamine-induced itch sensation by interaction with NaV1.7

Abstract

Itch can be induced by activation of small-diameter dorsal root ganglion (DRG) neurons which express abundant intracellular fibroblast growth factor 13 (FGF13). Although FGF13 is revealed to be essential for heat nociception, its role in mediating itch remains to be investigated. Here, we reported that loss of FGF13 in mouse DRG neurons impaired the histamine-induced scratching behavior. Calcium imaging showed that the percentage of histamine-responsive DRG neurons was largely decreased in FGF13-deficient mice, and consistently, electrophysiological recording exhibited that histamine failed to evoke action potential firing in most DRG neurons from these mice. Given that the reduced histamine-evoked neuronal response was caused by knockdown of FGF13 but not by FGF13A deficiency, FGF13B was supposed to mediate this process. Furthermore, overexpression of histamine type 1 receptor H1R, but not H2R, H3R nor H4R, increased the percentage of histamine-responsive DRG neurons, and the scratching behavior in FGF13-deficient mice was highly reduced by selective activation of H1R, suggesting that H1R is mainly required for FGF13-mediated neuronal response and scratching behavior induced by histamine. However, overexpression of H1R failed to rescue the histamine-evoked neuronal response in FGF13-deficient mice. Histamine enhanced the FGF13 interaction with NaV1.7. Disruption of this interaction by a membrane-permeable competitive peptide, GST-Flag-NaV1.7CT-TAT, reduced the percentage of histamine-responsive DRG neurons, and impaired the histamine-induced scratching, indicating that the FGF13/NaV1.7 interaction is a key molecular determinant in the histamine-induced itch sensation. Therefore, our study reveals a novel role of FGF13 in mediating itch sensation via the interaction of NaV1.7 in peripheral nervous system.

Abstract

Background: Chronic itch is a highly debilitating symptom among patients with inflammatory skin diseases. Recent studies have revealed that gastrin-releasing peptide (GRP) and its receptor (gastrin-releasing peptide receptor [GRPR]) in the spinal dorsal horn (SDH) play a central role in itch transmission.

Objective: We aimed to investigate whether GRP-GRPR signaling is altered in SDH neurons in a mouse model of chronic itch and to determine the potential mechanisms underlying these alterations.

Methods: Patch-clamp recordings from enhanced green fluorescent protein (EGFP)–expressing (GRPR1) SDH neurons were used to examine GRP-GRPR signaling in spinal cord slices obtained from Grpr-EGFP mice. Immunohistochemical, genetic (gene expression and editing through adeno-associated virus vectors), and behavioral approaches were also used for in vivo experiments.

Results: We observed potentiation of GRP-evoked excitation in the GRPR1 SDH neurons of mice with contact dermatitis, without concomitant changes in GRPR expression. Interestingly, increases in excitation were attenuated by suppressing the reactive state of SDH astrocytes, which are known to be reactive in patients with chronic itch conditions. Furthermore, CRISPR-Cas9–mediated astrocyte-selective in vivo editing of a gene encoding lipocalin-2 (LCN2), an astrocytic factor implicated in chronic itch, suppressed increases in GRP-induced excitation of GRPR1 neurons, repetitive scratching, and skin damage in mice with contact dermatitis. Moreover, LCN2 potentiated GRP-induced excitation of GRPR1 neurons in normal mice.

Conclusion: Our findings indicate that, under chronic itch conditions, the GRP-induced excitability of GRPR1 SDH neurons is enhanced through a non–cell-autonomous mechanism involving LCN2 derived from reactive astrocytes.

Key words: Contact dermatitis, chronic itch, gastrin-releasing peptide, gastrin-releasing peptide receptor, spinal dorsal horn neurons, astrocytes, lipocalin 2, CRISPR-Cas9, patch-clamp recordings

A vaccine targeting the RBD of the S protein of SARS-CoV-2 induces protective immunity

Abstract

The novel Coronavirus SARS-CoV-2 causes a respiratory illness called COVID-19 leading to a pandemic. An effective preventive vaccine against this virus is urgently needed. As the most critical step during infection, SARS CoV-2 uses its Spike protein receptor-binding domain (S- RBD) to engage with the host cell receptor angiotensin converting enzyme 2 (ACE2)1,2. Here we showed that a recombinant vaccine comprising residues 319-545 of the S-RBD could induce a potent functional antibody response in the immunized mice, rabbits and non-human primates (Macaca mulatta) as early as 7 or 14 days after a single dose injection. The sera from the immunized animals blocked RBD binding to ACE2 expressed on the cell surface and neutralized the infection by SARS-CoV-2 pseudovirus and live SARS-CoV-2 in vitro. Importantly, the vaccination also provided protection in non-human primates from SARS-CoV-2 challenge in vivo. The elevated RBD-specific antibodies were also found in the sera from patients with COVID-19. Several immune pathways and CD4 T lymphocytes were implicated in the induction of the vaccine antibody response. Our finding highlights the importance of the RBD domain in the SARS-CoV-2 vaccine design and provides the rationale for the development of a protective vaccine through the induction of antibody against the RBD domain.