Activating α7 nicotinic acetylcholine receptor inhibits NLRP3 inflammasome through regulation of β-arrestin-1

Abstract

<div class="section"> <a class="named-anchor" id="cns12758-sec-0001"> <!-- named anchor --> </a> <h5 class="section-title" id="d1138986e306">Aims</h5> <p id="d1138986e308">To evaluate whether activating α7 nicotinic acetylcholine receptor (α7n <span style="fixed-case">AC</span>hR) could inhibit the <span style="fixed-case">NOD</span>‐like receptor family, pyrin domain containing 3 ( <span style="fixed-case">NLRP</span>3) inflammasome through regulation of β‐arrestin‐1 in monocyte/macrophage system, thus contributing to the control of neuroinflammation. </p> </div><div class="section"> <a class="named-anchor" id="cns12758-sec-0002"> <!-- named anchor --> </a> <h5 class="section-title" id="d1138986e320">Methods</h5> <p id="d1138986e322">The protein levels of <span style="fixed-case">NLRP</span>3, caspase‐1 (Casp‐1) p20 and proCasp‐1, interleukin‐1β ( <span style="fixed-case">IL</span>‐1β) p17 and pro <span style="fixed-case">IL</span>‐1β, <span style="fixed-case">IL</span>‐18 and pro <span style="fixed-case">IL</span>‐18 were measured using Western blotting. The <span style="fixed-case">mRNA</span> levels of Casp‐1 and <span style="fixed-case">IL</span>‐1β were detected by real‐time <span style="fixed-case">PCR</span> ( <span style="fixed-case">RT</span>‐ <span style="fixed-case">PCR</span>). The colocalization and interaction of <span style="fixed-case">NLRP</span>3 protein and β‐arrestin‐1 were measured by immunofluorescence staining and immunoprecipitation. </p> </div><div class="section"> <a class="named-anchor" id="cns12758-sec-0003"> <!-- named anchor --> </a> <h5 class="section-title" id="d1138986e359">Results</h5> <p id="d1138986e361">The expression of β‐arrestin‐1 was significantly increased and colocalized with <span style="fixed-case">CD</span>45‐positive cells in spinal cord of experimental auto‐immune encephalomyelitis ( <span style="fixed-case">EAE</span>) mice when compared with the sham mice, which was attenuated by pretreatment with <span style="fixed-case">PNU</span>282987, a specific α7n <span style="fixed-case">AC</span>hR agonist. <span style="fixed-case">PNU</span>282987 also significantly inhibited the activation of <span style="fixed-case">NLRP</span>3 inflammasome and thus decreased the production of <span style="fixed-case">IL</span>‐1β and <span style="fixed-case">IL</span>‐18 both in lipopolysaccharide ( <span style="fixed-case">LPS</span>)/ <span style="fixed-case">ATP</span>‐stimulated <span style="fixed-case">BV</span>2 microglia in vitro and spinal cord from <span style="fixed-case">EAE</span> mice in vivo <i>,</i> while inverse effects were observed in α7n <span style="fixed-case">AC</span>hR knockout mice. Furthermore, overexpression of β‐arrestin‐1 attenuated the inhibitory effect of <span style="fixed-case">PNU</span>282987 on <span style="fixed-case">NLRP</span>3 inflammasome activation in <span style="fixed-case">LPS</span>/ <span style="fixed-case">ATP</span>‐stimulated <span style="fixed-case">BV</span>2 microglia. <span style="fixed-case">PNU</span>282987 inhibited the interaction between β‐arrestin‐1 and <span style="fixed-case">NLRP</span>3 protein in vitro. </p> </div><div class="section"> <a class="named-anchor" id="cns12758-sec-0004"> <!-- named anchor --> </a> <h5 class="section-title" id="d1138986e430">Conclusions</h5> <p id="d1138986e432">The present study demonstrates that activating α7n <span style="fixed-case">AC</span>hR can lead to <span style="fixed-case">NLRP</span>3 inflammasome inhibition via regulation of β‐arrestin‐1 in monocyte/microglia system. </p> </div>