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brain sciences Article NLRP12InflammasomeExpressionintheRatBrainin ResponsetoLPSduringMorphineTolerance SulieL.Chang1,2,*,WenfeiHuang1,XinMao1 andSabroniSarkar 1 1 InstituteofNeuroImmunePharmacology,SetonHallUniversity,400SouthOrangeAvenue,SouthOrange, NJ07079,USA;wenfei.huang@shu.edu(W.H.);ninnamao@yahoo.com.cn(X.M.); Sabroni.Sarkar@gmail.com(S.S.) 2 DepartmentofBiologicalSciences,SetonHallUniversity,400SouthOrangeAvenue,SouthOrange, NJ07079,USA * Correspondence: sulie.chang@shu.edu;Tel.:+1-973-761-9456;Fax:+1-973-275-2489 AcademicEditor:DonnaGruol Received: 22 June2016;Accepted: 16 January2017;Published: 6February2017 Abstract:Morphine, aneffectivebut addictiveanalgesic, canprofoundlyaffect the inflammatory response topathogens, and long-termuse can result inmorphine tolerance. Inflammasomesare proteincomplexes involved in the inflammatoryresponse. Thenucleotide-bindingoligomerization domain-likereceptor (NLR)FamilyPyrinDomainContaining(NLRP)12(NLRP12) inflammasome hasbeenreportedtohaveanti-inflammatoryactivity. In thisstudy,weexaminedtheexpressionof NLRP12inflammasomerelatedgenesintheadultF344ratbraininresponsetothebacterialendotoxin lipopolysaccharide(LPS) inthepresenceandabsenceofmorphinetolerance.Morphinetolerancewas elicitedusing the2+4morphine-pelletingprotocol.OnDay1, theratswerepelletedsubcutaneously with 2 pellets of morphine (75 mg/pellet) or a placebo; on Days 2 and 4 pellets were given. OnDay 5, the animalswere randomly assigned to receive either 250μg/kgLPS or saline (i.p.). Theexpressionof84 inflammasomerelatedgenes in theratbrainwasexaminedusingaPloymerase ChainReaction (PCR)array. Inresponse toLPS, therewasasignificant increase in theexpression of thepro-inflammatorycytokine/chemokinegenes interleukin-1beta (Il-1β), interleukin-6 (Il-6), C-Cmotif chemokine ligand2(Ccl2),C-Cmotif chemokine ligand7(Ccl7),C-X-Cmotif chemokine ligand 1 (Cxcl1), andC-X-Cmotif chemokine ligand 3 (Cxcl3) and a significant decrease in the anti-inflammatoryNLRP12gene inbothmorphine-tolerantandplacebo-control ratscomparedto saline-treatedrats, althoughthechangesweregreater in theplacebo-controlanimals. TheLibraryof IntegratedNetwork-BasedCellularSignatures’ (LINCS)connectivitymapwasusedtoanalyzethelist ofaffectedgenes to identifypotential targetsassociatedwith the interactionsofLPSandmorphine tolerance.Ourdata indicate that, in themorphine tolerantstate, theexpressionofNLRP12andits relatedgenes isaltered inresponse toLPSandthat theVacuolarprotein-sorting-associatedprotein28 (VPS28),which is involved in the transportandsortingofproteins intosub-cellularvesicles,maybe thekeyregulatorof thesealterations. Keywords:morphine tolerance;NLRP12 inflammasome;LPS 1. Introduction Morphine is apotent analgesic that iswidelyusedclinically forpainmanagement. However, long-termuseofmorphinecan leadtomorphine toleranceandaddiction[1]. Inaddition,morphine canprofoundlyanddetrimentallyaffect thebody’s immunesystem,atboth thecellularandmolecular levels. Morphine suppresses lymphocyte trafficking; decreasesnatural killer cell activity; inhibits the production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and BrainSci. 2017,7, 14 102 www.mdpi.com/journal/brainsci