2017.12.15

By

Transient Receptor Potential Vanilloid 4 Ion Channel Functions as a Pruriceptor in Epidermal Keratinocytes to Evoke Histaminergic Itch*

Abstract

TRPV4 ion channels function in epidermal keratinocytes and in innervating sensory neurons; however, the contribution of the channel in either cell to neurosensory function remains to be elucidated. We recently reported TRPV4 as a critical component of the keratinocyte machinery that responds to ultraviolet B (UVB) and functions critically to convert the keratinocyte into a pain-generator cell after excess UVB exposure. One key mechanism in keratinocytes was increased expression and secretion of endothelin-1, which is also a known pruritogen. Here we address the question of whether TRPV4 in skin keratinocytes functions in itch, as a particular form of “forefront” signaling in non-neural cells. Our results support this novel concept based on attenuated scratching behavior in response to histaminergic (histamine, compound 48/80, endothelin-1), not non-histaminergic (chloroquine) pruritogens in Trpv4 keratinocyte-specific and inducible knock-out mice. We demonstrate that keratinocytes rely on TRPV4 for calcium influx in response to histaminergic pruritogens. TRPV4 activation in keratinocytes evokes phosphorylation of mitogen-activated protein kinase, ERK, for histaminergic pruritogens. This finding is relevant because we observed robust anti-pruritic effects with topical applications of selective inhibitors for TRPV4 and also for MEK, the kinase upstream of ERK, suggesting that calcium influx via TRPV4 in keratinocytes leads to ERK-phosphorylation, which in turn rapidly converts the keratinocyte into an organismal itch-generator cell. In support of this concept we found that scratching behavior, evoked by direct intradermal activation of TRPV4, was critically dependent on TRPV4 expression in keratinocytes. Thus, TRPV4 functions as a pruriceptor-TRP in skin keratinocytes in histaminergic itch, a novel basic concept with translational-medical relevance.

Transient Receptor Potential Vanilloid 4 Ion Channel Functions as a Pruriceptor in Epidermal Keratinocytes to Evoke Histaminergic Itch

Journal Club 17.11.24

By

 

 

Involvement of thromboxane A2 in interleukin-31-induced itch-associated response in mice

저자 Andoh, Tsugunobu ⁎
Li, Sikai
Uta, Daisuke
자료유형 Article
초록 •Interleukinin-31 (IL-31) induced scratching, an itch-associated response, in mice.•IL-31-induced scratching was inhibited by TP thromboxane (TX) receptor antagonist.•IL-31 receptors were expressed mainly in epidermal keratinocytes.•IL-31 induced TXA2 production in the skin and primary cultures of keratinocytes.•The results suggest that IL-31 elicits scratching via epidermal TXA2 production.
Background Atopic dermatitis is a chronic and severe pruritic skin disease. Interlukin-31 (IL-31) has been recently demonstrated to be one of the key pruritogens in atopic dermatitis. However, the mechanisms underlying IL-31-induced itching remains unclear. In our previous study, we have shown that thromboxane (TX) A2 is involved in itch-associated responses in mice with atopy-like skin diseases.
Methods IL-31 was given intradermally into the rostral back of ICR mice and the hind-paw scratching to the injection site were counted. Expression of TX synthase and IL-31 receptors were analyzed using immunohistochemical staining or RT-PCR in mouse skin or primary cultures of mouse keratinocytes. The concentration of TXB2, a metabolite of TXA2, in the skin and the culture medium of primary cultures of mouse keratinocytes was measured using enzyme immunoassay. The concentration of intracellular Ca2+ ions in mouse keratinocytes was measured using the calcium imaging method.
Results An intradermal injection of IL-31 elicited scratching, an itch-related response, in mice. The scratching was inhibited by TP TXA2 receptor antagonist DCHCH. The distribution of TX synthase and IL-31RA receptor was mainly epidermal keratinocytes in the skin. The primary cultures of keratinocytes expressed the mRNAs of TX synthase and IL-31 receptors. IL-31 increased the concentration of TXB2, which was inhibited by TX synthase inhibitor sodium ozagrel and EGTA, in the skin and the culture medium of primary cultures of keratinocytes. IL-31 increased the concentration of intracellular Ca2+ ions in mouse keratinocytes.
Conclusion It is suggested that IL-31 elicits itch-associated responses through TXA2 produced from keratinocytes.
Affiliation Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
Publisher Elsevier Urban & Partner Sp. z o.o.
DOI 10.1016/j.pharep.2017.10.001
Accession Number S1734114017303808
Copyright © 2017 Published by Elsevier Sp. z o.o. on behalf of Institute of Pharmacology, Polish Academy of Sciences.

 

Involvement of thromboxane A2 in interleukin-31-induced itch-associated response in mice

 

 

 

 

17.10.20

By

Involvement of TRPV4 in Serotonin-Evoked Scratching.

Akiyama T1, Ivanov M2, Nagamine M2, Davoodi A2, Carstens MI2, Ikoma A3, Cevikbas F3, Kempkes C3, Buddenkotte J4, Steinhoff M5, Carstens E6.
Abstract

Several thermosensitive transient receptor potential channels (transient receptor potential vanilloid type-1, -3; transient receptor potential cation channel, subfamily A, member 1) have been implicated in itch. In contrast, the role of transient receptor potential vanilloid type-4 (TRPV4) in itch is unknown. Therefore, we investigated if TRPV4, a temperature-sensitive cation channel, plays an important role in acute itch in mice. Four different pruritogens, including serotonin (5-hydroxytryptamine [5-HT]), histamine, SLIGRL (protease-activated receptors 2/mas-related G-protein-coupled receptor C11 agonist), and chloroquine (mas-related G-protein-coupled receptor A3 agonist), were intradermally injected into mice and itch-related scratching behavior was assessed. TRPV4 knockout mice exhibited significantly fewer 5-HT-evoked scratching bouts compared with wild-type mice. Notably, no differences between TRPV4 knockout and wild-type mice were observed in the number of scratch bouts elicited by SLIGRL and histamine. Pretreatment with a TRPV4 antagonist significantly attenuated 5-HT-evoked scratching in vivo. Using calcium imaging in cultured primary murine dorsal root ganglion neurons, the response of neurons after 5-HT application, but not other pruritogens, was significantly lower in TRPV4 knockout compared with wild-type mice. A TRPV4 antagonist significantly suppressed 5-HT-evoked responses in dorsal root ganglion cells from wild-type mice. Approximately 90% of 5-HT-sensitive dorsal root ganglion neurons were immunoreactive for an antibody to TRPV4, as assessed by calcium imaging. These results indicate that 5-HT-induced itch is linked to TRPV4.

10.20. Involvement of TRPV4 in serotonin-evoked scratching

Journal Club 2017. 10. 13.

By

synergistic antipruritic effects of gamma aminobutyric acid A and B agonists ina a mouse model of atopic dermatitis

Ferda Cevikbas, PhD,a,b* Joao M. Braz, PhD,a* Xidao Wang, PhD,a Carlos Solorzano, PhD,a Mathias Sulk, MD,b,c
Timo Buhl, MD,b,d Martin Steinhoff, PhD,b,e,f,g,h and Allan I. Basbaum, PhDa

 

Atopic dermatitis (AD), an inflammatory, relapsing chronic
pruritic skin disease, is an often intractable form of chronic itch
that negatively impacts the quality of life of millions of patients.1
Unfortunately, because chronic itch conditions have very
different etiologies, most treatments have poor outcomes and
are accompanied by unacceptable adverse side effects, notably
sedation.2 Clearly, a better understanding of the pathophysiology
of these chronic itch conditions is critical to designing successful
therapeutic strategies.
Studies of the etiology of chronic itch3 generally focus on
changes in skin and immune dysfunction. However, there is
now considerable evidence for a contribution of primary afferent
pruritoceptors that transmit itch messages to spinal cord and
brainstem circuits engaged by and that regulate these messages.4
Of particular interest are studies demonstrating commonalities in
the mechanisms underlying nerve injury-induced neuropathic
pain and itch and the possibility that comparable approaches
may be appropriate for their management.5
Although there is evidence for specificity in the transmission of
itch and pain messages at the level of the primary afferent
nociceptor and pruritoceptor,6,7 both pain and itch are under
spinal cord inhibitory interneuron-mediated control. For example,
loss of spinal cord gamma aminobutyric acid (GABA) or glycinergic
function is a major contributor to the spontaneous pain and hypersensitivity
that develops following nerve injury.8-10 Moreover,
persistent scratching, a manifestation of chronic itch, occurs in the
Bhlhb5 mutant mouse, in which there is dramatic loss of dorsal
horn GABAergic inhibitory interneurons.11 Ablation of glycinergic
interneurons also induces excessive scratching and pain.12
And in a model of dry skin–induced scratching in the mouse,
GABA and glycine receptor antagonists can block scratchinginduced
inhibition of firing in superficial dorsal horn neurons.13
Finally, in patients, acute withdrawal of intrathecal baclofen, a
GABA-B receptor agonist, can induce pruritus.14
Given the evidence for a potential contribution of GABA
agonists in the management of pruritus, it is surprising that there
are no studies that assessed their utility in preclinical or clinical
conditions. Here, we demonstrate that both GABA-A and

GABA-B agonists are not only effective in models of acute itch,
but we also show that systemic administration of very low doses
of these agonists has synergistic antipruritic effects in IL-31
overexpressing transgenic mouse, a model of AD15 that is refractory
to antihistamines1,16 and thus particularly difficult to
manage. Most importantly, the antipruritic synergy could be produced
without concomitant sedation. Finally, we show that sustaining
high levels of GABA inhibition can be achieved using
intraspinal transplantation of cortical GABAergic interneuron
precursor cells. The transplants not only attenuated spontaneous
scratching but also dramatically reduced skin lesions in the IL-
31 overexpressing transgenic mouse (IL-31Tg) mice.

 

 

 

 

2017.08.25

By

Overexpression of TRPC3 reduces the content of intracellular calcium stores in HEK-293 cells.

Löf C1, Blom T, Törnquist K.

Abstract

The mammalian canonical transient receptor channels (TRPCs) are considered to be candidates for store-operated calcium channels (SOCCs). Many studies have addressed how TRPC3 channels are affected by depletion of intracellular calcium stores. Conflicting results have been shown for TRPC3 regarding its function, and this has been linked to its level of expression in various systems. In the present study, we have investigated how overexpression of TRPC3 interferes with the regulation of intracellular calcium stores. We demonstrate that overexpression of TRPC3 reduces the mobilization of calcium in response to stimulation of the cells with thapsigargin (TG) or the G-protein coupled receptor agonist sphingosine-1-phosphate (S1P). Our results indicate that this is the result of the expression of TRPC3 channels in the endoplasmic reticulum (ER), thus depleting ER calcium stores. OAG evoked calcium entry in cells overexpressing TRPC3, indicating that functional TRPC3 channels were also expressed in the plasma membrane. Taken together, our results show that overexpression of the putative SOCC, TRPC3, actually reduces the calcium content of intracellular stores, but does not enhance agonist-evoked or store-dependent calcium entry. Our results may, in part, explain the conflicting results obtained in previous studies on the actions of TRPC3 channels.

Overexpression of TRPC3 Reduces the Content of Intracellular Calcium Stores in HEK-293 Cells

A sensory neuron-expressed IL-31 receptor mediates T helper cell-dependent itch: Involvement of TRPV1 and TRPA1

By

1-s2.0-S0091674913017107-main

제목클릭하면 논문 다운로드 가능.

Abstract

BACKGROUND:

Although the cytokine IL-31 has been implicated in inflammatory and lymphoma-associated itch, the cellular basis for its pruritic action is yet unclear.

OBJECTIVE:

We sought to determine whether immune cell-derived IL-31 directly stimulates sensory neurons and to identify the molecular basis of IL-31-induced itch.

METHODS:

We used immunohistochemistry and quantitative real-time PCR to determine IL-31 expression levels in mice and human subjects. Immunohistochemistry, immunofluorescence, quantitative real-time PCR, in vivo pharmacology, Western blotting, single-cell calcium imaging, and electrophysiology were used to examine the distribution, functionality, and cellular basis of the neuronal IL-31 receptor α in mice and human subjects.

RESULTS:

Among all immune and resident skin cells examined, IL-31 was predominantly produced by TH2 and, to a significantly lesser extent, mature dendritic cells. Cutaneous and intrathecal injections of IL-31 evoked intense itch, and its concentrations increased significantly in murine atopy-like dermatitis skin. Both human and mouse dorsal root ganglia neurons express IL-31RA, largely in neurons that coexpress transient receptor potential cation channel vanilloid subtype 1 (TRPV1). IL-31-induced itch was significantly reduced in TRPV1-deficient and transient receptor channel potential cation channel ankyrin subtype 1 (TRPA1)-deficient mice but not in c-kit or proteinase-activated receptor 2 mice. In cultured primary sensory neurons IL-31 triggered Ca(2+) release and extracellular signal-regulated kinase 1/2 phosphorylation, inhibition of which blocked IL-31 signaling in vitro and reduced IL-31-induced scratching in vivo.

CONCLUSION:

IL-31RA is a functional receptor expressed by a small subpopulation of IL-31RA(+)/TRPV1(+)/TRPA1(+) neurons and is a critical neuroimmune link between TH2 cells and sensory nerves for the generation of T cell-mediated itch. Thus targeting neuronal IL-31RA might be effective in the management of TH2-mediated itch, including atopic dermatitis and cutaneous T-cell lymphoma.

Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Journal club 2017.7.28

By

The pruritus- and TH2-associated cytokine IL-31 promotes growth of sensory nerves.

Abstract

BACKGROUND:

Pruritus is a cardinal symptom of atopic dermatitis, and an increased cutaneous sensory network is thought to contribute to pruritus. Although the immune cell-IL-31-neuron axis has been implicated in severe pruritus during atopic skin inflammation, IL-31’s neuropoietic potential remains elusive.

OBJECTIVE:

We sought to analyze the IL-31-related transcriptome in sensory neurons and to investigate whether IL-31 promotes sensory nerve fiber outgrowth.

The pruritus and TH2associated cytokine IL31promotes growth of sensory nerves

2017.06.29

By

Asthma-like airway inflammation and responses in a rat model of atopic dermatitis induced by neonatal capsaicin treatment.

Han RT1,2, Kim S3, Choi K1,2, Jwa H1,2, Lee J1,2, Kim HY1,2, Kim HJ4, Kim HR5, Back SK6, Na HS1,2.

Abstract

Recent studies have shown that approximately 70% of patients with severe atopic dermatitis (AD) develop asthma. Development of AD in infancy and subsequent other atopic diseases such as asthma in childhood is referred to as atopic march. However, a causal link between the diseases of atopic march has remained largely unaddressed, possibly due to lack of a proper animal model. Recently, we developed an AD rat model showing chronically relapsing dermatitis and scratching behaviors induced by neonatal capsaicin treatment. Here, we investigated whether our model also showed asthmatic changes, with the aim of expanding our AD model into an atopic march model. First, we confirmed that capsaicin treatment (50 mg/kg within 24 h after birth) induced dermatitis and scratching behaviors until 6 weeks of age. After that, the mRNA expression of Th1 and Th2 cytokines, such as IFN-γ and TNF-α, and IL-4, IL-5, and IL-13, respectively, was quantified with quantitative real-time polymerase chain reaction in the skin and the lungs. The number of total cells and eosinophils was counted in bronchoalveolar lavage (BAL) fluid. The levels of IgE in the serum and BAL fluid were determined with enzyme-linked immunosorbent assay. Paraffin-embedded sections (4 μm) were stained with hematoxylin/eosin to analyze the morphology of the lung and the airway. Airway responsiveness was measured in terms of airway resistance and compliance using the flexiVent system. In the capsaicin-treated rats, persistent dermatitis developed, and scratching behaviors increased over several weeks. The levels of IgE in the serum and BAL fluid as well as the mRNA expression of Th2 cytokines, including IL-4, IL-5, and IL-13, in both the skin and the lungs were elevated, and the number of eosinophils in the BAL fluid was also increased in the capsaicin-treated rats compared to control rats. Morphological analysis of the airway revealed smooth muscle hypertrophy and extensive mucus plug in the capsaicin-treated rats. Functional studies demonstrated an increment of the airway resistance and a decrement of lung compliance in the capsaicin-treated rats compared to control rats. Taken together, our findings suggested that neonatal capsaicin treatment induced asthma-like airway inflammation and responses in juvenile rats.

17.06.30

2017.06.09

By

Methylglyoxal evokes pain by stimulating TRPA1.

Andersson DA1, Gentry C, Light E, Vastani N, Vallortigara J, Bierhaus A, Fleming T, Bevan S.

Abstract

Diabetic neuropathy is a severe complication of long-standing diabetes and one of the major etiologies of neuropathic pain. Diabetes is associated with an increased formation of reactive oxygen species and the electrophilic dicarbonyl compound methylglyoxal (MG). Here we show that MG stimulates heterologously expressed TRPA1 in CHO cells and natively expressed TRPA1 in MDCK cells and DRG neurons. MG evokes [Ca(2+)]i-responses in TRPA1 expressing DRG neurons but is without effect in neurons cultured from Trpa1(-/-) mice. Consistent with a direct, intracellular action, we show that methylglyoxal is significantly more potent as a TRPA1 agonist when applied to the intracellular face of excised membrane patches than to intact cells. Local intraplantar administration of MG evokes a pain response in Trpa1(+/+) but not in Trpa1(-/-) mice. Furthermore, persistently increased MG levels achieved by two weeks pharmacological inhibition of glyoxalase-1 (GLO-1), the rate-limiting enzyme responsible for detoxification of MG, evokes a progressive and marked thermal (cold and heat) and mechanical hypersensitivity in wildtype but not in Trpa1(-/-) mice. Our results thus demonstrate that TRPA1 is required both for the acute pain response evoked by topical MG and for the long-lasting pronociceptive effects associated with elevated MG in vivo. In contrast to our observations in DRG neurons, MG evokes indistinguishable [Ca(2+)]i-responses in pancreatic β-cells cultured from Trpa1(+/+) and Trpa1(-/-) mice. In vivo, the TRPA1 antagonist HC030031 impairs glucose clearance in the glucose tolerance test both in Trpa1(+/+) and Trpa1(-/-) mice, indicating a non-TRPA1 mediated effect and suggesting that results obtained with this compound should be interpreted with caution. Our results show that TRPA1 is the principal target for MG in sensory neurons but not in pancreatic β-cells and that activation of TRPA1 by MG produces a painful neuropathy with the behavioral hallmarks of diabetic neuropathy.

journal.pone.0077986

2017.06.02

By

Mouse model of imiquimod-induced psoriatic itch.

Sakai K1, Sanders KM, Youssef MR, Yanushefski KM, Jensen L, Yosipovitch G, Akiyama T.

Abstract

Itch is a major indicator of psoriasis, but the underlying mechanisms behind this symptom are largely unknown. To investigate the neuronal mechanisms of psoriatic itch, we tested whether mice subjected to the imiquimod-induced psoriasis model exhibit itch-associated behaviors. Mice received daily topical applications of imiquimod to the rostral back skin for 7 days. Imiquimod-treated mice exhibited a significant increase in spontaneous scratching behavior directed to the treated area as well as touch-evoked scratching (alloknesis). To characterize this model, we measured the mRNA expression levels of pruritogens and itch-relevant receptors/channels using real-time reverse transcription PCR. The mRNA expression of MrgprA3, MrgprC11, and MrgprD decreased gradually over time in the dorsal root ganglion (DRG) cells. There was no significant change in the mRNA expression of TRPV1 or TRPA1 in DRG cells. TRPV4 mRNA expression was transiently increased in the DRG cells, whereas TRPM8 mRNA was significantly decreased. The mRNA expression levels of histidine decarboxylase and tryptophan hydroxylase 1, as well as the intensity of histamine and serotonin immunoreactivity, were transiently increased in the skin on day 2, returning to baseline by day 7. Histamine H1-receptor antagonists, chlorpheniramine and olopatadine, significantly inhibited spontaneous scratching on day 2, but not day 7. Neither chlorpheniramine nor olopatadine affected alloknesis on day 2 or day 7. These results may reflect the limited antipruritic effects of histamine H1-receptor antagonists on human psoriasis. The imiquimod-induced psoriasis model seems to be useful for the investigation of itch and its sensitization in psoriasis.

00006396-201611000-00019

Scroll to Top