Microglia are Involved in Pruritus Induced by DNFB via the CX3CR1/p38 MAPK Pathway

Zhang, Ying; Jia, Yan; Hu, Rong; Sun, Yu; Ma, Yu; Chen, Zhifeng; Jiang, Hong

doi:10.1159/000373929

Cited by 35 publications

(42 citation statements)

References 44 publications

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“…Our data establish that (i) KP enhances Kcc2 gene expression in rat and mouse primary cortical neurons Based on these findings, we also were curious about KP's anti-pruritic effects because inhibitory transmission in the SCDH plays an important role in chronic pruritus (Akiyama et al, 2015;Bourane et al, 2015;Braz et al, 2017;Braz et al, 2014;Koch et al, 2018;Mishra and Hoon, 2015). In a 2,4-dinitrofluorobenzene (DNFB) chronic contact dermatitis model (Zhang et al, 2015), daily i.p injections of KP (30 mg/kg) significantly reduced robust scratching behavior of sensitized sites (Suppl Fig. 2).…”

Section: Compound Screen In Primary Cortical Neurons For Kcc2 Gene Exmentioning

confidence: 52%

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Repurposing cell growth-regulating compounds identifies kenpaullone which ameliorates pathologic pain via normalization of inhibitory neurotransmission

Yeo

Jiang

et al. 2019

Preprint

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Inhibitory GABA-ergic neurotransmission is of fundamental relevance for the adult vertebrate central nervous system and requires low chloride ion concentration in neurons. This basic ionic-homeostatic mechanism critically relies on expression and function of KCC2, a neuroprotective ionic transporter that extrudes neuronal chloride. Attenuated expression of KCC2 causes circuit malfunction in chronic pain and other neuropsychiatric illnesses. To find new analgesics, we screened 1057 cell growth-regulating compounds in cultured mouse primary cortical neurons for enhancement of Kcc2 gene expression. We identified kenpaullone (KP), which enhanced Kcc2/KCC2 expression and function in cultured rodent and human neurons by inhibiting GSK3ß. KP effectively reduced pathologic pain in preclinical mouse models. In nerve-injury pain, KP restored Kcc2 expression and GABA-evoked chloride reversal potential in the spinal cord dorsal horn. Delta-catenin, a phosphorylation-target of GSK3ß in neurons, activated the Kcc2 promoter via Kaiso transcription factor, and transient spinal transgenesis of delta-catenin mimicked KP's analgesic effects.1D), which is accompanied by increased KCC2 protein expression and increased expression of synaptophysin ( Fig. 1E-F). This latter finding suggests increased synaptic maturation. These data indicate that our rationally designed screen identified a GSK3/CDK kinase inhibitor, KP, that enhances Kcc2/KCC2 gene expression and not KCC2-mediated chloride extrusion in CNS neurons. KP functions as Kcc2/KCC2 gene expression enhancer in mammals including humans, where we document enhanced synaptic maturation and increased KCC2 expression and function. ============================= Fig. 1========================= Fig. 1. Compound screening for enhancers of Kcc2 expression in primary cortical neurons yields KenpaulloneA, primary mouse neurons, B-C: primary rat neurons. D-F: primary human neurons. A) Top panel: Screening paradigm using three rounds of primary screen based on luciferase (LUC) activity followed by secondary screen including Kcc2 RT-qPCR and Clomeleon chloride imaging. Bottom panel: Four compound "winners" including Kenpaullone (KP). Screening conducted in primary mouse neurons. B) Primary rat cortical neurons. Bar diagram: dose-dependent increase in Kcc2 mRNA expression after KP treatment, also reflected by increased protein expression as shown by KCC2 immuno-label (micrographs). Results represent the average mRNA expression of 4 independent neuronal cultures. p<0.05, one-way ANOVA C) Primary rat cortical neurons. Neuronal [Cl-]i, measured with ratiometric chloride indicator, clomeleon, is robustly and significantly reduced after KP treatment. Note that add-on treatment with KCC2-transport blocker, VU0240551, leads to a [Cl-]i ≥120mM, for both, vehicle-treated and KP-treated, indicating that KP's chloride lowering effect relies on KCC2 chloride extruding transport function. n≥75 neurons from 3 independent cultures; * p<0.01, t-test D) Primary human cortical neurons. KCC2 mRNA increases in a KP...

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Section: Compound Screen In Primary Cortical Neurons For Kcc2 Gene Exmentioning

confidence: 52%

“…To study itch, mice were sensitized with 0.5% 2,4-dinitrofluorobenzene (DNFB) topically to their dorsal neck, as in (Zhang et al, 2015). KP was injected i.p at 30 mg/kg following an experimental time-line as shown in Suppl Fig.…”

Section: Behavioral Assessmentsmentioning

confidence: 99%

Repurposing cell growth-regulating compounds identifies kenpaullone which ameliorates pathologic pain via normalization of inhibitory neurotransmission

Yeo

Jiang

et al. 2019

Preprint

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“…Itch behavioral Scratching behaviors were performed as previously described [10]. Behavioral tests were videotaped (HDR-CX190, Canon) at the animal plastic arena.…”

Section: Itch Modelsmentioning

confidence: 99%

Nalbuphine Attenuates Microglial Activation and Inhibits Morphine-Induced Scratching via Regulation of PKCδ and p38 Signaling in Mice

Tang

Huang

et al. 2020

Preprint

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Morphine-induced scratching (MIS) is a common issue in patients receiving clinical postoperative morphine intrathecal injections. The kappa opioid receptor (KOR) agonist nalbuphine is known to prevent and reduce MIS, but the underlying mechanism has remained unclear. Here, we found that protein kinase C (PKCβ) in the spinal cord dorsal horn was co-expressed with ionized calcium binding adapter molecule 1 (Iba1) and increased after morphine intrathecal (i.t.) injections in mice. Although knockdown PKCβ inhibited microglial activation and attenuated MIS, but nalbuphine can blocked MIS by promoting PKCδ expression rather than PKCβ expression, suggesting that antipruritic effect of nalbuphine is due to activation of the KOR/PKCδ pathway and that MIS is both PKCβ-dependent and closely related to microglial activation. Moreover, we also found that PKCδ could retroegulation microglial activation, thereby reversing nalbuphine’s inhibition of MIS and resulting in increased itching behaviors. Notably, microglial activation is required for p-p38 signaling in MIS. These data together suggest that nalbuphine activates KOR, so as to inducing the activation of PKCδ, which may in turn retroegulation microglial function and decrease phosphorylate p38, ultimately inhibiting MIS. Our research therefore indicates that a previously unknown KOR-PKCδ-microglia-p38 pathway in the spinal cord may underlie nalbuphine’s antipruritic effect.

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“…In a chronic itch mouse model, spinal microglia were activated after scratching, and suppression of microglia via minocycline treatment in turn reduced the level of scratching 32 . A similar pattern was observed in a mouse model of atopic dermatitis.…”

Section: Central Interactions Between Neurons and Gliamentioning

confidence: 99%

Advances in understanding itching and scratching: a new era of targeted treatments

2016

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Chronic itch is a significant health burden with few effective treatments. As such, itch researchers seek to understand the mechanisms behind itch and to find potential targets for treatment. The field of itch research is dynamic, and many advances have been made so far this decade. In particular, major steps forward include the identification of new peripheral and central itch mediators and modulators, the discovery of greater roles for immune cells and glia in itch transmission, and a focus on the brain processing of itching and scratching. Finally, several new therapeutic interventions for itch have shown success in clinical trials.

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Microglia are Involved in Pruritus Induced by DNFB via the CX3CR1/p38 MAPK Pathway

Cited by 35 publications

References 44 publications

Repurposing cell growth-regulating compounds identifies kenpaullone which ameliorates pathologic pain via normalization of inhibitory neurotransmission

Repurposing cell growth-regulating compounds identifies kenpaullone which ameliorates pathologic pain via normalization of inhibitory neurotransmission

Nalbuphine Attenuates Microglial Activation and Inhibits Morphine-Induced Scratching via Regulation of PKCδ and p38 Signaling in Mice

Advances in understanding itching and scratching: a new era of targeted treatments

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