Optogenetic activation of spinal microglia triggers chronic pain in mice.

Spinal microglia are highly responsive to peripheral nerve injury and are known to be a key player in pain. However, there has not been direct evidence showing that selective microglial activation in vivo is sufficient to induce chronic pain. Here, we used optogenetic approaches in microglia to addr...

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Main Authors: Min-Hee Yi, Yong U Liu, Anthony D Umpierre, Tingjun Chen, Yanlu Ying, Jiaying Zheng, Aastha Dheer, Dale B Bosco, Hailong Dong, Long-Jun Wu
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2021-03-01
Series:PLoS Biology
Online Access:https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.3001154&type=printable
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author Min-Hee Yi
Yong U Liu
Anthony D Umpierre
Tingjun Chen
Yanlu Ying
Jiaying Zheng
Aastha Dheer
Dale B Bosco
Hailong Dong
Long-Jun Wu
author_facet Min-Hee Yi
Yong U Liu
Anthony D Umpierre
Tingjun Chen
Yanlu Ying
Jiaying Zheng
Aastha Dheer
Dale B Bosco
Hailong Dong
Long-Jun Wu
author_sort Min-Hee Yi
collection DOAJ
description Spinal microglia are highly responsive to peripheral nerve injury and are known to be a key player in pain. However, there has not been direct evidence showing that selective microglial activation in vivo is sufficient to induce chronic pain. Here, we used optogenetic approaches in microglia to address this question employing CX3CR1creER/+: R26LSL-ReaChR/+ transgenic mice, in which red-activated channelrhodopsin (ReaChR) is inducibly and specifically expressed in microglia. We found that activation of ReaChR by red light in spinal microglia evoked reliable inward currents and membrane depolarization. In vivo optogenetic activation of microglial ReaChR in the spinal cord triggered chronic pain hypersensitivity in both male and female mice. In addition, activation of microglial ReaChR up-regulated neuronal c-Fos expression and enhanced C-fiber responses. Mechanistically, ReaChR activation led to a reactive microglial phenotype with increased interleukin (IL)-1β production, which is likely mediated by inflammasome activation and calcium elevation. IL-1 receptor antagonist (IL-1ra) was able to reverse the pain hypersensitivity and neuronal hyperactivity induced by microglial ReaChR activation. Therefore, our work demonstrates that optogenetic activation of spinal microglia is sufficient to trigger chronic pain phenotypes by increasing neuronal activity via IL-1 signaling.
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spelling doaj-art-c6166d65b9ee46e2a96c73e2ace0859e2025-08-20T02:18:15ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852021-03-01193e300115410.1371/journal.pbio.3001154Optogenetic activation of spinal microglia triggers chronic pain in mice.Min-Hee YiYong U LiuAnthony D UmpierreTingjun ChenYanlu YingJiaying ZhengAastha DheerDale B BoscoHailong DongLong-Jun WuSpinal microglia are highly responsive to peripheral nerve injury and are known to be a key player in pain. However, there has not been direct evidence showing that selective microglial activation in vivo is sufficient to induce chronic pain. Here, we used optogenetic approaches in microglia to address this question employing CX3CR1creER/+: R26LSL-ReaChR/+ transgenic mice, in which red-activated channelrhodopsin (ReaChR) is inducibly and specifically expressed in microglia. We found that activation of ReaChR by red light in spinal microglia evoked reliable inward currents and membrane depolarization. In vivo optogenetic activation of microglial ReaChR in the spinal cord triggered chronic pain hypersensitivity in both male and female mice. In addition, activation of microglial ReaChR up-regulated neuronal c-Fos expression and enhanced C-fiber responses. Mechanistically, ReaChR activation led to a reactive microglial phenotype with increased interleukin (IL)-1β production, which is likely mediated by inflammasome activation and calcium elevation. IL-1 receptor antagonist (IL-1ra) was able to reverse the pain hypersensitivity and neuronal hyperactivity induced by microglial ReaChR activation. Therefore, our work demonstrates that optogenetic activation of spinal microglia is sufficient to trigger chronic pain phenotypes by increasing neuronal activity via IL-1 signaling.https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.3001154&type=printable
spellingShingle Min-Hee Yi
Yong U Liu
Anthony D Umpierre
Tingjun Chen
Yanlu Ying
Jiaying Zheng
Aastha Dheer
Dale B Bosco
Hailong Dong
Long-Jun Wu
Optogenetic activation of spinal microglia triggers chronic pain in mice.
PLoS Biology
title Optogenetic activation of spinal microglia triggers chronic pain in mice.
title_full Optogenetic activation of spinal microglia triggers chronic pain in mice.
title_fullStr Optogenetic activation of spinal microglia triggers chronic pain in mice.
title_full_unstemmed Optogenetic activation of spinal microglia triggers chronic pain in mice.
title_short Optogenetic activation of spinal microglia triggers chronic pain in mice.
title_sort optogenetic activation of spinal microglia triggers chronic pain in mice
url https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.3001154&type=printable
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