Thecentral roleofneuroinflammation inthepathogenesisofneurodegenerativediseases andbraindisordershas spurred the development of Positron Emission Tomography (PET) radiotracers to investigate neuroimmune mechanisms noninvasivelyinvivo.Becauseit isexpressedinglia, thepurinergicP2X7receptor(P2X7R)isavalidatedtarget forinvivoimaging ofneuroinflammation,analternativetothe18kDatranslocatorprotein,whichiscurrentlythestandardtargetforneuroinflammation inclinicalpractice.However, clinicallyvalidatedP2X7RPETradiotracers remainneeded.Thepresent studyaimedtoidentifya novelmolecularscaffoldfordevelopinganeffectiveP2X7RPETradiotracer,startingfromthreechemotypeswithantagonistactivity inthenanomolarrangeathumanP2X7R, toexploit structuraldiversityandmeet themultidimensionalkeyattributes thataCNS PETradiotracermusthave.Thus,weevaluatedtheselectedchemotypesacrossarangeofproperties, includingradioligandbinding affinityat thehumanP2X7receptor,off-targetselectivity, invitrometabolicstability, andnonspecificbindingtobraintissue.Our study pointed to compound 2 (2-chloro-3-methoxy-N-[2-morpholino-2-[6-(trifluoromethyl)pyridin-3-yl]ethylbenzamide) as a promisingmolecularscaffoldtodeliveraneffectivePETtracerbecauseofitsnanomolaraffinityforhumanclonedP2X7R,broadofftargetselectivity,highinvitrometabolicstability,passivepermeabilityacrosstwomodelmembranemonolayers, limitedinteraction withblood-brainbarriereffluxtransporters, andbrainfreefractionpredictiveof lowinvivononspecificbinding.Toensurerobust translatability,wealsoevaluatedthebindingaffinityofcompound2inhumanmeningiomasbyautoradiographyandfoundthatthe compoundbinds tonativeP2X7Rwithhighaffinity(IC50=72nM).
A Holistic Approach to Identifying a Positron Emission Tomography (PET) Tracer Candidate for In Vivo Imaging of Purinergic P2X7 Receptor in Neuroinflammation
Ricci, LudovicaInvestigation
;Grignolo, MariannaInvestigation
;Adinolfi, ElenaData Curation
;
2026
Abstract
Thecentral roleofneuroinflammation inthepathogenesisofneurodegenerativediseases andbraindisordershas spurred the development of Positron Emission Tomography (PET) radiotracers to investigate neuroimmune mechanisms noninvasivelyinvivo.Becauseit isexpressedinglia, thepurinergicP2X7receptor(P2X7R)isavalidatedtarget forinvivoimaging ofneuroinflammation,analternativetothe18kDatranslocatorprotein,whichiscurrentlythestandardtargetforneuroinflammation inclinicalpractice.However, clinicallyvalidatedP2X7RPETradiotracers remainneeded.Thepresent studyaimedtoidentifya novelmolecularscaffoldfordevelopinganeffectiveP2X7RPETradiotracer,startingfromthreechemotypeswithantagonistactivity inthenanomolarrangeathumanP2X7R, toexploit structuraldiversityandmeet themultidimensionalkeyattributes thataCNS PETradiotracermusthave.Thus,weevaluatedtheselectedchemotypesacrossarangeofproperties, includingradioligandbinding affinityat thehumanP2X7receptor,off-targetselectivity, invitrometabolicstability, andnonspecificbindingtobraintissue.Our study pointed to compound 2 (2-chloro-3-methoxy-N-[2-morpholino-2-[6-(trifluoromethyl)pyridin-3-yl]ethylbenzamide) as a promisingmolecularscaffoldtodeliveraneffectivePETtracerbecauseofitsnanomolaraffinityforhumanclonedP2X7R,broadofftargetselectivity,highinvitrometabolicstability,passivepermeabilityacrosstwomodelmembranemonolayers, limitedinteraction withblood-brainbarriereffluxtransporters, andbrainfreefractionpredictiveof lowinvivononspecificbinding.Toensurerobust translatability,wealsoevaluatedthebindingaffinityofcompound2inhumanmeningiomasbyautoradiographyandfoundthatthe compoundbinds tonativeP2X7Rwithhighaffinity(IC50=72nM).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
