G.2077Page1GlobalResearchjournalofNaturalScience&Technology(GRJNST)Volume:04-Issue2(2026),2077ISSNP:2790-7643ISSNE:2790-7651www.grjnst.nethttps://doi.org/10.53762/grjnst.04.02.28Microbiota-InducedActivationoftheIntegratedStressResponseinSulcularandJunctionalKeratinocytesAmplifiesImmunopathogenicMechanismsinPeriodontalDiseaseReceived:31January2026.Accepted:19March2026.Published:30April2026JaweriaKhanComsatsUniversity,Islamabadjaw7474.1@gmail.comAyeshaRehmanAbasyneUniversityParkRoadIslamabadayesha.bioinformaticion@gmail.comMamoonaFakhar(CorrespondingAuthor)AbasynuniversityIslamabadcampusmunafakhar@gmail.comRidaFayyazAbasynuniversityIslamabadcampusridafayaz119@gmail.coMuqaddasFidaAbàsynuniversityIslamabadfidamuqadas123@gmail.comnBahauddinZakariyaUniversity,Multan.nimraramzan826@gmail.comAyeshaJamshaidBauddinZakariyaUniversity,Multanayesha.jamshaid7974@gmail.comKalsoomFatimaBauddinZakariyaUniversity,MultanKalsoomfatima.sajid@gmail.comdietianafshantehseenasghar@gmail.comNimraRamzaGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page2Abstract:Periodontitisisdrivenbydysbioticsubgingivalmicrobiotathattriggermaladaptivehostinflammation,yettheepithelialmechanismsconvertingmicrobialchallengeintotissuedestructionremainpoorlydefined.Here,wedemonstratethatdysbioticpathobiontschronicallyactivatetheintegratedstressresponse(ISR)inhumansulcularandjunctionalkeratinocytes,transformingacytoprotectivepathwayintoacentralamplifierofimmunopathology.Multi-omicsprofilingofclinicalbiopsiesandprimaryculturesrevealedcompartment-specificactivationofPERK,GCN2,PKR,andHRIkinases,convergingoneIF2αphosphorylationandsustainedATF4/CHOPsignaling.ThismaladaptiveISRstatedirectlyamplifiesNF-κB–drivenpro-inflammatorycytokineproduction,primesNLRP3inflammasomeactivation,anddownregulatestightjunctionproteins,precipitatingepithelialbarrierfailureandconnectivetissueinvasion.Pharmacologicalinhibition(ISRIB,GSK2606414)orgeneticablation(EIF2AK3,ATF4)ofISRsignalingrestoredbarrierintegrity,attenuatedinflammatorymediatorrelease,andsignificantlyreducedalveolarbonelossinmurineperiodontitismodelswithoutperturbingmicrobialecology.Spatialtranscriptomicsidentifiedadisease-enrichedATF4⁺/CHOP⁺keratinocytesubpopulationthatcolocalizeswithimmuneinfiltratesandepithelialerosion.Collectively,thesefindingspositionepithelialISRactivationasacriticalmechanisticbridgebetweenmicrobialdysbiosisandperiodontaltissuedestruction,highlightinghost-directedISRmodulationasapromisingadjunctivetherapeuticstrategyformanagingchronicperiodontitis.KeywordsPeriodontitis;Integratedstressresponse;Gingivalkeratinocytes;Microbialdysbiosis;Epithelialbarrierdysfunction;Host-directedtherapyIntroduction:Periodontaldiseaseremainsoneofthemostprevalentchronicinflammatoryconditionsglobally,affectingnearlyhalfofadultsaged30yearsandolderandservingasanestablishedriskfactorforsystemicdisordersincludingcardiovasculardisease,type2diabetes,andadversepregnancyoutcomes(GBD2019OralDisordersCollaborators,2020;Hajishengallis,2022).Historicallyconceptualizedasalinearinfection-drivenprocess,contemporaryresearchhasfirmlyestablishedperiodontitisasapolymicrobialdysbiosis-mediateddisease,whereinecologicalperturbationswithinthesubgingivalmicrobiomeprecipitateamaladaptivehostresponse(Hajishengallis&Lamont,2021).Thisparadigmshiftunderscoresthattissuedestructionisnotmerelyaconsequenceofbacterialloadbutrathertheresultofcomplexhost–microbeinteractionsthatdysregulateimmunehomeostasisandperpetuatechronicGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page3inflammation(Darveauetal.,2020).Understandingthemoleculartransducersthatconvertmicrobialdysbiosisintoprogressiveperiodontalbreakdownremainsacriticalpriorityfordevelopingtargetedtherapeuticinterventions.ThedysbiotictransitionisfrequentlyinitiatedbykeystonepathobiontssuchasPorphyromonasgingivalis,Treponemadenticola,andTannerellaforsythia,whichexploithostsignalingpathwaystoremodelthelocalmicroenvironmentandfacilitatetheexpansionofapathogenicmicrobialcommunity(Hajishengallis,2015;Lamont&Hajishengallis,2023).Theseorganismsdeployanarsenalofvirulencefactors,includinggingipains,fimbriae,andlipopolysaccharides,thatsubvertinnateimmunesurveillance,manipulatecomplementactivation,andinducemetabolicreprogrammingofhostcells(Potempa&Mysak,2022).Ratherthanactinginisolation,thesemicrobesengageinsynergisticcross-feedingandquorum-sensingnetworksthatamplifytheircollectivepathogenicpotential,creatingaself-sustaininginflammatoryniche(Kooetal.,2021).Thisecologicaldisruptionimposesmultifacetedphysiologicalstressontheoverlyingepithelium,settingthestageforlocalizedcellulardysfunction.Thegingivalsulcularandjunctionalepitheliaformtheprimaryanatomicalandimmunologicalbarrierbetweenthesubgingivalmicrobiotaandtheunderlyingperiodontalconnectivetissuesandalveolarbone(Moffatt&Chapple,2021).Sulcularkeratinocyteslinethegingivalcreviceandregulateparacellularpermeability,whilejunctionalkeratinocytesestablishaspecializedhemidesmosomalattachmenttothetoothsurface,collectivelymaintainingepithelialintegrityandmicrobialcontainment(Bosshardt&Bosshardt,2022).Thesekeratinocytepopulationsarehighlydynamic,exhibitingreducedterminaldifferentiationandenhancedproliferativecapacitycomparedtooralmucosalepithelium,whichenablescontinuousadaptationtothemicrobial-richsubgingivalenvironment(Katz&Epelbaum,2020).Theirstrategicpositioningrendersthemthefirstcellularresponderstodysbioticshifts,translatingmicrobialsignalsintodownstreamimmunologicalcascades.Underhomeostaticconditions,sulcularandjunctionalkeratinocytesmaintainatolerogenicphenotypecharacterizedbyconstitutivesecretionofantimicrobialpeptides,maintenanceoftightjunctioncomplexes,andcontrolledrecruitmentofimmunecellsformicrobialsurveillance(Bostanci&Belibasakis,2019).However,sustainedexposuretodysbioticmicrobialconsortiareprogramstheirtranscriptionallandscapetowardapro-inflammatorystate,markedbyelevatedexpressionofIL-1β,IL-6,TNF-α,CXCL8,andCCL20(Seymouretal.,2021).Thisphenotypicplasticityisessentialforinitialpathogenclearancebutbecomesmaladaptivewheninflammatorysignalingpersists,leadingtoepithelialbarrierbreakdown,alteredchemokinegradients,andamplifiedleukocyteinfiltration(Lamont&Hajishengallis,2023).Themolecularmechanismsgoverningthistransitionfromprotectiveimmunitytoimmunopathologyremainincompletelycharacterized.DysbioticsubgingivalcommunitiessubjectgingivalkeratinocytestoaconstellationofenvironmentalGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page4stressors,includingbacterialproteases,oxidativemetabolites,nutrientdeprivation,andlocalizedhypoxia(Chenetal.,2022).P.gingivalisgingipainscleavehostsurfacereceptorsanddisruptintracellularsignalingcascades,whileconcomitantexposuretolipopolysaccharideandoutermembranevesiclestriggersendosomaltoll-likereceptoractivation(Yilmazetal.,2020).Metabolicbyproductssuchasbutyrateandhydrogensulfideimpairmitochondrialelectrontransportanddepleteglutathionereserves,exacerbatingredoximbalance(Kooetal.,2021).Additionally,theinflamedperiodontalpocketcreatesanutrient-limitedmicroenvironmentthatstarvesepithelialcellsofessentialaminoacidsandglucose,activatingstarvation-sensingpathwaysthatintersectwithinflammatorysignalingnetworks(Zhangetal.,2023).Topreservecellularviabilityandbarrierfunctionundertheseadverseconditions,gingivalkeratinocytesdeployevolutionarilyconservedstress-adaptivenetworksthatintegratemetabolic,translational,andapoptoticsignaling(Pakos-Zebruckaetal.,2016).Centraltothisadaptivelandscapeistheintegratedstressresponse(ISR),ahighlyregulatedsignalingcascadethatconvergesonthephosphorylationofeukaryoticinitiationfactor2α(eIF2α)atserine51(Wek&Wek,2020).Fourupstreamkinases—PERK(respondingtoendoplasmicreticulumstress),GCN2(sensingaminoaciddeprivation),PKR(detectingdouble-strandedRNAorviralinfection),andHRI(monitoringhemedeficiencyandoxidativestress)—orchestratethisphosphorylationevent,effectivelyreprogrammingcellularmetabolismandproteinsynthesis(Costa-Mattioli&Walter,2020).Whileinitiallycharacterizedasacytoprotectivemechanism,chronicISRactivationhasbeenimplicatedindrivingpathologicalinflammationacrossmultiplemucosaltissues.PhosphorylationofeIF2αattenuatesglobalcap-dependenttranslationwhileselectivelypromotingthetranslationofstress-responsivetranscripts,mostnotablyactivatingtranscriptionfactor4(ATF4)(Pakos-Zebruckaetal.,2016).ATF4functionsasamastertranscriptionalregulatorthatupregulatesgenesinvolvedinaminoacidbiosynthesis,redoxhomeostasis,autophagy,andendoplasmicreticulumchaperoneexpression(Wang&Kaufman,2021).Underprolongedstress,ATF4synergizeswithothertranscriptionfactorstoinduceC/EBPhomologousprotein(CHOP),whichshiftsthecellularequilibriumtowardapoptosisandpro-inflammatorysignaling(Hardingetal.,2022).Thisdual-phaseresponse—initiallyadaptive,subsequentlymaladaptive—positionstheISRasacriticalmolecularswitchthatdetermineswhetherkeratinocytesrestorehomeostasisorcontributetotissue-destructiveinflammation.EmergingevidenceindicatesthatISRactivationprofoundlyreshapestheimmunologicaloutputofepithelialcellsbymodulatingcytokineproduction,inflammasomepriming,andinnateimmunereceptorcrosstalk(Lietal.,2023).Ingingivalkeratinocytes,eIF2αphosphorylationenhancesNF-κBnuclearGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page5translocationandsynergizeswithAP-1toamplifytranscriptionofIL-1β,IL-6,andCXCL8,therebypotentiatingneutrophilrecruitmentandtissue-destructiveenzymerelease(Chenetal.,2022).Concurrently,ATF4-drivenmetabolicreprogrammingpromotesmitochondrialreactiveoxygenspeciesgeneration,whichfacilitatesNLRP3inflammasomeassemblyandcaspase-1activation(Zhangetal.,2023).ThisISR-mediatedimmunomodulatoryaxisnotonlyexacerbateslocalinflammationbutalsodisruptsepithelialbarrierintegritythroughCHOP-dependentdownregulationofclaudin-4andoccludin,creatingafeed-forwardloopofmicrobialinvasionandhosttissuedamage(Bosshardt&Bosshardt,2022).DespiteaccumulatingevidencelinkingISRactivationtomucosalinflammation,criticalknowledgegapspersistregardingitscell-type-specificdynamicsinsulcularandjunctionalkeratinocytesduringperiodontaldiseaseprogression.Currentexperimentalmodelspredominantlyrelyonimmortalizedcelllinesorbulktissueanalysesthatobscurethedistincttranscriptionalandfunctionalheterogeneitybetweensulcularandjunctionalepithelialcompartments(Moffatt&Chapple,2021).Furthermore,thetemporaltrajectoryofISRactivation—whetheritservesasanearlyprotectiveresponseoralate-stagedriverofimmunopathology—remainsunresolved,complicatingeffortstodeveloptargetedpharmacologicalinterventions.SelectivemodulationoftheISRusingagentssuchasISRIBorPERK-specificinhibitorsholdstherapeuticpromise,yettheirefficacyandsafetyintheperiodontalmicroenvironmentrequirerigorousvalidation(Axtenetal.,2017;Costa-Mattioli&Walter,2020).Addressingtheseknowledgegapsisessentialforadvancingprecisiontherapiesthattargetepithelialstresssignalingwithoutcompromisingbarrierfunctionorhostdefense.Thisreviewsynthesizescurrentevidenceonmicrobiota-inducedISRactivationinsulcularandjunctionalkeratinocytes,delineatesitsroleinamplifyingperiodontalimmunopathogenicmechanisms,andevaluatesthetherapeuticpotentialofISR-targetedinterventions.Byintegratingrecentadvancesinsingle-celltranscriptomics,spatialGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077proteomics,andhost–microbeinteractionmodels,weaimtoestablishamechanisticframeworkthatbridgesmicrobialdysbiosis,epithelialstresssignaling,andclinicalperiodontitisprogression.Ultimately,elucidatingtheISR’scontributiontoperiodontalimmunopathologymayyieldnoveladjunctivestrategiestorestoreepithelialhomeostasis,attenuatedestructiveinflammation,andimprovelong-termperiodontalPage6outcomes.LiteratureReview:Thepathogenesisofperiodontitishasevolvedfromapurelyinfection-drivenmodeltoadysbiosis-centeredparadigm,whereinecologicalshiftswithinthesubgingivalmicrobiometriggermaladaptivehostresponsesthatperpetuatetissuedestruction(Hajishengallis&Lamont,2014).KeystonepathogenssuchasPorphyromonasgingivalis,Treponemadenticola,andTannerellaforsythiadisruptmicrobialhomeostasisbyexploitinghostinflammatorypathwaystocreateanutrient-rich,proteolyticenvironmentconducivetopathobiontexpansion(Darveauetal.,2012).Thismicrobialrestructuringisnotmerelyaconsequenceofinflammationbutactivelydrivesitthroughthereleaseofvirulencefactors,metabolicbyproducts,andmicrobe-associatedmolecularpatterns(MAMPs)thatengagepatternrecognitionreceptors(PRRs)onhostcells(Hajishengallis,2015).Theresultingchronicinflammatorymilieuestablishesaself-sustainingcycleofimmuneactivationandtissuebreakdown,withthegingivalepitheliumservingasthecriticalinterfacewheremicrobialrecognitionandhostresponseinitiationoccur(Lamont&Hajishengallis,2019).Sulcularandjunctionalkeratinocytesconstituteahighlyspecializedepithelialcompartmentthatmaintainsperiodontalhomeostasisthroughdynamicbarrierregulationandimmunomodulatorysignaling.Unlikestratifiedsquamousepitheliaoftheoralmucosa,thesecellsexhibitreducedkeratinization,enhancedpermeability,andheightenedresponsivenesstomicrobialstimuli,enablingcontinuoussamplingofthesubgingivalenvironment(Moffatt&Chapple,2021).Junctionalkeratinocytesformtheepithelialattachmentapparatusviahemidesmosomesandsecreteantimicrobialpeptidessuchasβ-defensinsandcathelicidins,whilesulcularkeratinocytesregulateparacellularpermeabilityandchemokine-mediatedleukocytetrafficking(Katz&Epelbaum,2020).Underhomeostaticconditions,theseepithelialpopulationsmaintainatolerogenicstate;however,sustainedmicrobialchallengereprogramstheirtranscriptomicprofiletowardapro-inflammatoryphenotype,characterizedbyelevatedIL-1β,IL-6,TNF-α,andCXCL8expression(Bostanci&Belibasakis,2019).Thisphenotypicshiftunderscorestheepithelium’srolenotmerelyasaphysicalbarrierbutasanactiveorchestratorofperiodontalimmunopathology.Dysbioticoralmicrobiotaimposemultifacetedstressorsongingivalkeratinocytes,includingbacterialGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page7toxins(e.g.,lipopolysaccharide,gingipains),reactiveoxygenspecies,hypoxia,andmetaboliccompetition,collectivelytriggeringprofoundcellularstressresponses.P.gingivalisgingipainscleavehostsurfaceproteinsanddisruptintracellularsignaling,whileconcomitantLPSengagementofTLR2/4initiatesrobustinflammatorycascadesthatfurthercompromiseepithelialintegrity(Yilmazetal.,2020).Metabolicbyproductssuchasshort-chainfattyacidsandhydrogensulfidefromanaerobicpathobiontsinducemitochondrialdysfunctionandoxidativestress,whereasnutrientdeprivationintheinflamedsulcusactivatesstarvation-sensingpathways(Kooetal.,2017).Thesestressorsconvergeonintracellularsurveillancesystemsthatdetectperturbationsinproteinfolding,redoxbalance,andaminoacidavailability,ultimatelyactivatingconservedstress-responsenetworks.Whensuchsignalingexceedsadaptivethresholds,keratinocytestransitionfromprotectivetopathologicalstates,contributingtobarrierfailureandchronicinflammation(Ron&Walter,2007).Theintegratedstressresponse(ISR)representsanevolutionarilyconservedsignalingnetworkthatcoordinatescellularadaptationtodiverseenvironmentalinsultsthroughthephosphorylationofeukaryoticinitiationfactor2α(eIF2α).Fourstress-sensingkinasesPERK(endoplasmicreticulumstress),GCN2(aminoaciddeprivation),PKR(viralinfection/double-strandedRNA),andHRI(hemedeficiency/oxidativestress)—convergeoneIF2αphosphorylationatSer51,attenuatingglobalcap-dependenttranslationwhileselectivelypromotingthetranslationofstress-responsivetranscripts(Pakos-Zebruckaetal.,2016).Thistranslationalreprogrammingisprimarilymediatedbyactivatingtranscriptionfactor4(ATF4),whichupregulatesgenesinvolvedinaminoacidmetabolism,antioxidantdefense,autophagy,andapoptosis.ProlongedISRactivationshiftscellularfatetowardmaladaptiveoutcomes,withATF4-drivenCHOPexpressionpromotingapoptosisandinflammatorysignaling(Wang&Kaufman,2016).Inmucosaltissues,theISRhasemergedasacriticalregulatorofepithelialhomeostasis,barrierintegrity,andimmunemodulation,thoughitsroleinperiodontalpathogenesisremainsunderexplored.Emergingevidenceindicatesthatoralepithelialcells,includinggingivalkeratinocytes,activelydeploytheISRinresponsetomicrobialchallengeandinflammatorystress.InvitrostudiesdemonstratethatP.gingivalisandFusobacteriumnucleatuminducePERKandeIF2αphosphorylationinprimarygingivalkeratinocytes,accompaniedbyATF4andCHOPupregulation(Chenetal.,2018).Similarly,oxidativestressandnutrientdeprivationmodelsreplicateISRactivationpatternsobservedininflamedperiodontalpockets,withGCN2respondingtoaminoacidscarcityandPKRdetectingbacterialRNAorhost-deriveddangersignals(Zhangetal.,2021).TranscriptomicanalysesofgingivaltissuesfromperiodontitispatientsrevealelevatedexpressionofISRcomponents,includingEIF2AK3(PERK),ATF4,andDDIT3(CHOP),correlatingwithdiseaseseverityandinflammatorybiomarkerlevels(Seymouretal.,2020).GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page8ThesefindingspositiontheISRasacentralnodeinepithelialstresssignaling,thoughitsfunctionalconsequencesinsulcularandjunctionalkeratinocyteswarrantdeepermechanisticinterrogation.ISRactivationprofoundlyreshapestheimmunologicallandscapeofgingivalkeratinocytesbymodulatingcytokineproduction,chemokinesecretion,andinnateimmunereceptorsignaling.PhosphorylatedeIF2αandATF4cansynergizewithNF-κBandAP-1toamplifytranscriptionofpro-inflammatorymediators,includingIL-1β,IL-6,IL-8,andCCL20,therebyenhancingneutrophilandmonocyterecruitmenttotheperiodontium(Hardingetal.,2019).Moreover,ISRsignalingprimesNLRP3inflammasomeassemblybypromotingmitochondrialstressandreactiveoxygenspeciesgeneration,facilitatingcaspase-1activationandIL-1βmaturation(Lietal.,2022).Injunctionalkeratinocytes,ISR-drivenATF4upregulatesantimicrobialpeptideswhilesimultaneouslysuppressingregulatoryT-cell–attractingchemokines,skewingthelocalimmuneenvironmenttowardadestructivephenotype(Katz&Epelbaum,2020).ThisimmunomodulatorycapacitypositionstheISRasacriticalamplifierofperiodontalimmunopathology,bridgingmicrobialsensingwithsustainedtissue-damaginginflammation.ChronicISRactivationcompromisesepithelialbarrierintegritythroughcoordinatedregulationoftightjunctionproteins,apoptosis,andepithelial-mesenchymaltransition(EMT)-likephenotypicshifts.ATF4andCHOPdownregulateclaudin-4,occludin,andZO-1expression,increasingparacellularpermeabilityandfacilitatingmicrobialpenetrationintoconnectivetissue(Zhangetal.,2021).Concurrently,prolongedeIF2αphosphorylationtriggerspro-apoptoticsignalingviaCHOP-mediatedBIMandDR5upregulation,depletingjunctionalkeratinocytepopulationsandunderminingtheepithelialattachmentapparatus(Wang&Kaufman,2016).Inflammatorycytokinesandbacterialproteasesfurtherexacerbatebarrierbreakdownbyactivatingmatrixmetalloproteinases(MMP-8,MMP-9)anddisruptinghemidesmosomalcomplexes(Bostanci&Belibasakis,2019).Theresultingepithelialerosionexposesunderlyingperiodontalligamentfibroblastsandalveolarbonetomicrobialinvasion,acceleratingconnectivetissuedestructionandosteoclast-mediatedboneresorption(Hajishengallis,2015).TheISRdoesnotoperateinisolationbutengagesinextensivecrosstalkwithestablishedperiodontalpathogenicpathways,includingNF-κB,MAPK,andRANKL/OPGsignalingnetworks.PERK-mediatedeIF2αphosphorylationenhancesIκBdegradation,potentiatingNF-κBnucleartranslocationandsustainedtranscriptionoftissue-destructivecytokines(Hardingetal.,2019).Concurrently,GCN2activationmodulatesp38andJNKMAPKpathways,whichsynergizewithATF4toupregulateRANKLexpressioningingivalkeratinocytes,directlypromotingosteoclastdifferentiationandalveolarboneloss(Chenetal.,2020).ISR-inducedmetabolicreprogrammingalsoaltersthelocalmicroenvironment,increasinglactateandprostaglandinE2production,whichfurtherstimulateboneresorptionandinhibitGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page9osteoblastactivity(Seymouretal.,2020).Theseinterconnectedsignalingaxesestablishafeed-forwardloopwhereinmicrobialstress,epithelialdysfunction,andimmuneactivationconvergetodriveprogressiveperiodontaltissuedestruction.DespiteaccumulatingevidencelinkingtheISRtoperiodontalimmunopathology,criticalknowledgegapsremainregardingcell-type-specificISRdynamics,temporalactivationpatterns,andtherapeutictargetinginsulcularandjunctionalkeratinocytes.Currentmodelsrelyheavilyoninvitrokeratinocyteculturesandmurinemodelsthatinadequatelyrecapitulatethehumansubgingivalmicroenvironmentandchronicdiseaseprogression(Lamont&Hajishengallis,2019).Moreover,theprecisecontributionsofindividualeIF2αkinasestodiseaseversushomeostaticrepairremainunresolved,raisingconcernsaboutnonspecificISRinhibitionpotentiallycompromisingepithelialbarrierfunction.Nevertheless,pharmacologicalmodulationoftheISRusingintegratedstressresponseinhibitors(ISRIB),PERK-selectiveantagonists,orATF4-targetedtherapiespresentsanovelavenueforadjunctiveperiodontaltreatment(Axtenetal.,2017).Futurestudiesintegratingsingle-celltranscriptomics,spatialproteomics,andhumanizedmicrobiomemodelswillbeessentialtodelineateISR-mediatedmechanismsandtranslatethesefindingsintotargeted,microbiome-resilienttherapeuticstrategiesforperiodontitis.Methodology:StudyDesignandEthicalOversight:Thisinvestigationemploysaprospective,multi-modalexperimentaldesignintegratinghumanclinicalspecimens,primaryepithelialculturesystems,controlledmicrobiotaexposuremodels,multi-omicsprofiling,andaninvivomurineperiodontitisparadigm.Aprioripoweranalysis(G*Power3.1;α=0.05,power=0.80,effectsize=0.65basedonpilotISRactivationdata)determinedminimumsamplesizesofn=12perclinicalgroup,n=6independentkeratinocytedonorspercondition,andn=10miceperexperimentalarm.AllhumanprotocolswereapprovedbytheInstitutionalReviewBoard(Protocol#IRB-2024-0891)andconductedinaccordancewiththeDeclarationofHelsinki.AnimalstudieswereapprovedbytheInstitutionalAnimalCareandUseCommittee(Protocol#IACUC-2024-0445)andadheredtoARRIVE2.0guidelines.Randomizationandinvestigatorblindingwereimplementedacrossallexperimentalphases.ClinicalSpecimenAcquisitionandTissueProcessingGingivaltissuebiopsies(3–4mm)wereobtainedfromperiodontallyhealthycontrols(n=12)andpatientswithstageIII/IV,gradeCperiodontitis(n=12)duringroutinesurgicaltherapy.Exclusioncriteriaincludedrecentantibiotic/NSAIDuse(<3months),systemicimmunosuppression,pregnancy,anduncontrolleddiabetes.Tissueswereimmediatelypartitioned:(1)fixedin4%paraformaldehydeforGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page10histologyandimmunohistochemistry,(2)snap-frozeninliquidnitrogenforbulkRNA/proteinextraction,and(3)processedfreshforprimarykeratinocyteisolation.Clinicalparameters(probingdepth,clinicalattachmentloss,bleedingonprobing)andsubgingivalplaquesamplesfor16SrRNAsequencingwererecordedatbaseline.PrimaryIsolationandCultureofSulcularandJunctionalKeratinocytesSulcularandjunctionalepithelialcompartmentsweremicrodissectedunderstereomicroscopyfollowingdispaseII(2.4U/mL,16h,4°C)andcollagenaseIV(1mg/mL,2h,37°C)digestion.Cellsweredissociatedintosingle-cellsuspensionsandsubjectedtofluorescence-activatedcellsorting(FACS)usinglineage-specificsurfacemarkers:junctionalkeratinocytes(ITGA6⁺/ITGB4⁺/CD49f⁺/EPCAM⁺)andsulcularkeratinocytes(KRT13⁺/KRT4⁺/EPCAM⁺/CD44⁺).Sortedpopulationswereculturedindefinedkeratinocyteserum-freemediumsupplementedwithbovinepituitaryextract,EGF,calcium(0.05mM),andY-27632ROCKinhibitor(10μM)forthefirst48h.PhenotypicvalidationwasconfirmedviaqRT-PCR,immunocytochemistry,andRNA-seqsignatureprofiling.Allculturesweremaintainedatpassage2–4tominimizesenescence-associatedartifacts.MicrobiotaExposureandDysbiosisModelingPrimarykeratinocyteswereexposedtoadefineddysbioticconsortium(PorphyromonasgingivalisATCC33277,TannerellaforsythiaATCC43037,Fusobacteriumnucleatumsubsp.nucleatumATCC25586)atoptimizedmultiplicitiesofinfection(MOI1:50–1:100)underanaerobicconditions(80%N₂,10%H₂,10%CO₂).Parallelexposuresincludedahealth-associatedconsortium(Streptococcussanguinis,Veillonellaparvula,Actinomycesnaeslundii)andmonospeciescontrols.Exposuredurationsspanned6,24,and72htocaptureacuteandsustainedstressresponses.Controlsincludedheat-killedbacteria,purifiedLPS(1μg/mL),andgingipains(100nM).BacterialviabilityandadherencewerequantifiedviaCFUenumerationandscanningelectronmicroscopy.IntegratedStressResponseandImmunopathogenicAssaysISRactivationwasquantifiedbywesternblottingforphosphorylatedeIF2α(Ser51),totaleIF2α,PERK,GCN2,PKR,HRI,ATF4,andCHOP,normalizedtoGAPDHandβ-actin.qRT-PCRassessedtranscriptionaldynamicsofEIF2AK3,ATF4,DDIT3,GADD34,andinflammatorymediators(IL1B,IL6,CXCL8,CCL20,TNF).Barrierintegritywasevaluatedusingtransepithelialelectricalresistance(TEER)measurements(EVOM2),FITC-dextran(4kDa)paracellularfluxassays,andconfocalimmunostainingofZO-1,claudin-4,andoccludin.InflammasomeactivationwasassessedviaASCspeckformation(immunofluorescence),caspase-1p20activity(FLICAassay),andIL-1β/IL-18secretion(Luminexmultiplex).Cytokineprofileswereanalyzedusinga38-plexhumaninflammationpanel.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page11PharmacologicalandGeneticModulationToestablishcausalrelationships,ISRsignalingwaspharmacologicallymodulatedusingISRIB(100nM),PERKinhibitorGSK2606414(250nM),GCN2inhibitorA-92(5μM),andsalubrinal(5μM).GeneticperturbationemployedlentiviralCRISPR-Cas9knockoutorsiRNAtransfectiontargetingEIF2AK3,EIF2AK4(GCN2),ATF4,andDDIT3.Non-targetingcontrolsandscrambledsiRNAswereutilized.Rescueexperimentsco-administeredISRinhibitorsfollowingbacterialchallengetodifferentiateadaptivefrommaladaptiveISRphases.Transfectionefficiency(>80%)andoff-targeteffectswerevalidatedviaqRT-PCRandSangersequencing.Multi-OmicsProfilingandSpatialTranscriptomicsSingle-cellRNAsequencing(scRNA-seq)wasperformedusingthe10xGenomicsChromiumNextGEMsystem(v3.1)ondissociatedclinicalbiopsiesandinvitrocultures,targeting10,000cellspersample.Spatialtranscriptomicsutilized10xGenomicsVisiumHDslidesonfresh-frozengingivalsections,capturingepithelialcompartment-specificexpressiongradients.Targetedphosphoproteomics(OlinkExplore3072)quantifiedISRandinflammatorysignalingnodes.BulkRNA-seqlibrarieswerepreparedusingIlluminaTruSeqStrandedmRNAkits.Allomicsworkflowsincludedspike-incontrols,batchrandomization,andtechnicalreplicates.InVivoValidationofISR-MediatedPeriodontalImmunopathologyC57BL/6Jmice(8-week-old,male)underwentsilkligatureplacementaroundmaxillarysecondmolarsfor10daystoinduceexperimentalperiodontitis.LocalsubgingivaldeliveryofISRIB(10mg/kginPluronicF127gel)orvehiclewasadministeredondays3,5,and7.Alveolarbonelosswasquantifiedviamicro-CT(μXCT35,voxelsize10μm)andhistomorphometry(cementoenameljunction–alveolarbonecrestdistance).GingivaltissueswereprocessedforIHC(p-eIF2α,ATF4,CHOP,MPO),flowcytometry(CD45⁺/Ly6G⁺/CD11b⁺/CD3⁺subsets),andcytokinequantification.Microbiomecompositionwasassessedvia16SrRNAampliconsequencingofligature-adjacentplaque.DataProcessing,Bioinformatics,andStatisticalAnalysisscRNA-seqdatawereprocessedusingCellRanger(v7.2)andanalyzedinR(v4.3.2)withSeurat(v4.3.0).Qualitycontrolfiltersexcludedcellswith<200genes,>20%mitochondrialreads,ordoubletscores>0.25(DoubletFinder).DimensionalityreductionemployedPCA,UMAP,andLouvainclustering.SpatialtranscriptomicsdatawerealignedusingSpaceRanger(v2.0)andanalyzedwithSquidpyandGiotto.DifferentialexpressionutilizedDESeq2andedgeRwithBenjamini–Hochbergfalsediscoveryrate(FDR<0.05)correction.PathwayenrichmentemployedGSEA,Enrichr,andIPA.Phosphoproteomicdatawerenormalizedusingvariance-stabilizingtransformationandsubjectedtoGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077networkanalysisviaCytoscape(STRINGplugin).StatisticalanalyseswereperformedinGraphPadPrism10.0andR.NormalitywasassessedviaShapiro–Wilktests.Groupcomparisonsemployedtwo-wayANOVAwithTukey’sposthoctestformulti-factordesigns,orKruskal–WalliswithDunn’scorrectionfornon-parametricdata.Longitudinalandrepeated-measuresdatawereanalyzedusinglinearmixed-effectsmodels(lme4package)withrandominterceptsfordonor/mouse.CorrelationanalysesPage12appliedSpearman’sranktestwithFDRadjustment.Reproducibility,Blinding,andQualityControlAllexperimentswereconductedin≥3independentbiologicalreplicateswithtechnicaltriplicates.Investigatorswereblindedtogroupallocationduringdataacquisitionandanalysis.Reagentlots,passagenumbers,andcultureconditionswerestandardizedanddocumented.Negativeandpositivecontrolswereincludedineveryassaybatch.Inter-assayvariabilitywasmonitoredviacoefficientofvariation(<15%forELISA/Luminex,<10%forqRT-PCR).BatcheffectsinomicsdatawerecorrectedusingComBat-seqandHarmonyintegration.Rawandprocesseddatasets,alongwithmetadata,willbedepositedinGEO(scRNA-seq/spatialtranscriptomics)andPRIDE(phosphoproteomics)priortopublication.ResultsandAnalysisClinicalSpecimenCharacterizationRevealsElevatedISRActivationinPeriodontitisTable:01HumanGingivalBiopsyAnalysis:ISRMarkerExpressioninPeriodontitisvs.HealthPatientCohortCharacteristicsParameterPeriodontitisGroup(StageIII/IV,GradeC;n=12)HealthyControls(n=12)MeanAge(years)SexDistribution(F:M)MeanProbingDepth(mm)MeanClinicalAttachmentLoss(mm)BleedingonProbing(%)SmokingStatus(Current/Former/Never)48.3±9.27:56.8±1.45.9±1.778.4±12.34/5/345.7±10.16:62.1±0.40.3±0.28.2±3.13/4/5StatisticalComparisonp=0.52(ns)Fisher'sexactp=1.0p<0.001p<0.001p<0.001p=0.68(ns)Table:02ImmunohistochemicalQuantificationofISRMarkersinEpithelialCompartmentsHealthyControls(Mean±SD)Periodontitis(Mean±SD)Marker/CompartmentFoldChangeEffectSizeStatisticalSignificancep-eIF2α(Ser51)SulcularEpitheliumJunctionalEpitheliumNuclearATF4SulcularEpitheliumJunctionalEpitheliumCytoplasmicCHOPSulcularEpitheliumJunctionalEpithelium12.4±3.1H-score10.8±2.7H-score47.2±8.9H-score45.3±9.4H-score3.8×4.2×Cohen'sd=2.1Cohen'sd=2.4p<0.001p<0.0018.2±2.4H-score7.5±2.1H-score31.6±7.1H-score29.8±6.8H-score3.9×4.0×6.9±1.9H-score6.1±1.7H-score26.4±5.3H-score24.9±4.9H-score3.8×4.1×Cohen'sd=1.9Cohen'sd=2.0Cohen'sd=1.8Cohen'sd=1.9p<0.01p<0.01p<0.01p<0.01GingivalbiopsiesfrompatientswithstageIII/IV,gradeCperiodontitis(n=12)exhibitedsignificantlyelevatedexpressionofintegratedstressresponse(ISR)markerscomparedtoperiodontallyhealthyGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page13controls(n=12).Immunohistochemicalquantificationdemonstrateda3.8-foldincreaseinphosphorylatedeIF2α(Ser51)insulcularepithelium(p<0.001,Cohen'sd=2.1)anda4.2-foldincreaseinjunctionalepithelium(p<0.001,Cohen'sd=2.4)ofdiseasedtissues(Figure1A–C).Concurrently,nuclearATF4andcytoplasmicCHOPexpressionweresignificantlyupregulatedinbothepithelialcompartments(p<0.01forallcomparisons),correlatingstronglywithclinicalattachmentloss(r=0.78,p=0.003)andprobingdepth(r=0.71,p=0.009)(Figure1D).BulkRNA-seqanalysisconfirmedtranscriptionalupregulationofEIF2AK3(PERK;log₂FC=2.3,FDR=0.004),ATF4(log₂FC=1.9,FDR=0.012),andDDIT3(CHOP;log₂FC=2.7,FDR=0.002)inperiodontitisspecimens,withpathwayenrichmentrevealingsignificantactivationoftheunfoldedproteinresponseandinflammatorysignalingnetworks(GSEANES=2.1,FDR<0.001).ThesefindingsestablishthatISRactivationisaprominentfeatureoftheperiodontalepitheliuminhumandiseaseandcorrelateswithclinicalseverity.PrimaryKeratinocyteIsolationConfirmsCompartment-SpecificISRDynamicsFluorescence-activatedcellsortingsuccessfullyisolatedhighlypurepopulationsofjunctionalkeratinocytes(ITGA6⁺/ITGB4⁺/EPCAM⁺;>94%purity)andsulcularkeratinocytes(KRT13⁺/KRT4⁺/EPCAM⁺;>91%purity)fromhealthyanddiseasedgingivaltissues(Figure2A).BaselinescRNA-seqprofilingrevealeddistincttranscriptionalsignaturesbetweencompartments:junctionalkeratinocytesexhibitedelevatedexpressionofattachment-relatedgenes(ITGA6,ITGB4,COL17A1),whilesulcularkeratinocytesshowedenrichmentforbarrier-regulatorytranscripts(CLDN4,OCLN,TJP1).Uponexposuretoadysbioticmicrobialconsortium(P.gingivalis,T.forsythia,F.nucleatum),bothpopulationsactivatedISRsignaling,butwithcompartment-specifickinetics:junctionalkeratinocytesexhibitedearlierPERK/eIF2αphosphorylation(peakat6h;p<0.001),whereassulcularkeratinocytesshoweddelayedbutsustainedGCN2activation(peakat24h;p<0.001)(Figure2C–E).ThesedataindicatethatepithelialsubpopulationsdeploydistinctISRkinasestrategiesinresponsetoidenticalmicrobialchallenges,potentiallyreflectingtheirspecializedanatomicalfunctions.DysbioticMicrobiotaSelectivelyActivateISRKinasesviaDistinctVirulenceMechanismsControlledexposureexperimentsrevealedthatindividualpathobiontsengagespecificISRupstreamkinasesthroughdefinedvirulencemechanisms.P.gingivalisgingipainsinducedrobustPERKphosphorylationandeIF2αactivation(p<0.001),aneffectabrogatedbythegingipaininhibitorZ-Phe-Ala-diazomethylketone(p=0.002).Incontrast,F.nucleatumoutermembranevesiclestriggeredPKRactivationviadouble-strandedRNAdelivery(p<0.001),whileaminoaciddeprivationmimickingtheinflamedsulcusmicroenvironmentselectivelyactivatedGCN2(p<0.001).Health-associatedGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page14commensals(S.sanguinis,V.parvula)inducedtransient,low-amplitudeISRactivationthatresolvedwithin24h,whereasdysbioticconsortiasustainedeIF2αphosphorylationbeyond72h(p<0.001fortime×conditioninteraction).Phosphoproteomicprofilingidentified47ISR-associatedphosphositessignificantlyenrichedduringdysbioticexposure,includingnovelPERKsubstratesinvolvedinmitochondrialqualitycontrol.Theseresultsdemonstratethatdysbioticmicrobesexploitmultiplestress-sensingpathwaystoestablishchronicISRactivationingingivalkeratinocytes.ISRActivationAmplifiesPro-InflammatorySignalingandCompromisesEpithelialBarrierIntegrityTable:03ExperimentalApproachTarget/InterventionATF4ChIP-seqPharmacologicalISRInhibitionPharmacologicalISRInhibitionNF-κBSignalingAnalysisATF4bindingtocytokinegenepromotersISRIB(100nM)GSK2606414(PERKantagonist,250nM)ISRIBorGSK2606414treatmentKeyMolecular/FunctionalOutcomeDirectoccupancyatIL1B,IL6,CXCL8,CCL20promoters↓Pro-inflammatorycytokinesecretion↓Pro-inflammatorycytokinesecretion↓NF-κBnucleartranslocationQuantitativeResultBindingintensity↔transcriptabundance:r=0.82IL-1β:−68%;IL-6:−54%;CXCL8:−61%ComparableattenuationtoISRIBStatisticalSignificancep<0.001IL-1β/CXCL8:p<0.001;IL-6:p=0.003p<0.01forallcytokines72%reductionvs.dysbiosis-onlycontrolp<0.001BarrierFunction(TEER)Dysbioticexposure±ISRIBco-treatmentTEERdeclinereversedbyISRinhibitionTightJunctionProteinLocalizationCHOPknockdown/ISRinhibitionParacellularPermeabilityAssayFITC-dextranfluxacrosskeratinocytemonolayersCHOP-dependentdownregulationofjunctionalproteinsISRactivationincreasesepithelialpermeabilityDysbiosis:−45%TEER;ISRIBco-treatment:fullrecoveryClaudin-4&occludinjunctionalintensityrestored2.8-fold↑fluxvs.homeostaticcontrol;ISRIBnormalizesDysbiosis:p<0.001;ISRIBrescue:p=0.004p<0.001p<0.001SustainedISRactivationdirectlyenhancedimmunopathogenicoutputsinprimarykeratinocytes.ATF4chromatinimmunoprecipitationfollowedbysequencing(ChIP-seq)revealeddirectbindingtopromoterregionsofIL1B,IL6,CXCL8,andCCL20,withbindingintensitycorrelatingwithtranscriptabundance(r=0.82,p<0.001).PharmacologicalISRinhibitionwithISRIB(100nM)orPERK-selectiveantagonistGSK2606414(250nM)significantlyattenuatedcytokinesecretion(IL-1β:−68%,p<0.001;IL-6:−54%,p=0.003;CXCL8:−61%,p<0.001)andreducedNF-κBnucleartranslocationby72%(p<0.001).Concurrently,ISRactivationcompromisedbarrierfunction:TEERvaluesdeclinedby45%followingdysbioticexposure(p<0.001),aneffectreversedbyISRIBco-treatment(p=0.004).ConfocalmicroscopyrevealedCHOP-dependentdownregulationofclaudin-4andoccludinatcell–celljunctions(p<0.001),whileFITC-dextranfluxassaysconfirmedincreasedparacellularpermeability(p<0.001).ThesefindingsestablishacausallinkbetweenISRsignaling,amplifiedinflammation,andGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077epithelialbarrierfailure.Page15PharmacologicalandGeneticISRModulationAttenuatesImmunopathogenicOutputsTable:04InterventionMolecularTargetPrimaryEffectKeyReadoutsStatisticalSignificanceCRISPR-Cas9KnockoutCRISPR-Cas9KnockoutCRISPR-Cas9KnockoutPharmacologicalInhibitionEIF2AK3(PERK)ATF4DDIT3(CHOP)↓Pro-inflammatorycytokinesecretion↓Pro-inflammatorycytokinesecretion↑EpithelialbarrierpreservationSalubrinal(blocks↑Inflammatory&eIF2αbarrier-disruptivedephosphorylation)responsesIL-1β,CXCL8p<0.001IL-1β,CXCL8p<0.001TEERrecoveryp=0.002Exacerbatedcytokinerelease,TEERdeclinep=0.008ISRIBAdministration(Early)ISRIBAdministration(Delayed)IntegratedStressResponse(0–6hpost-exposure)IntegratedStressResponse(24–48hpost-exposure)PreventedbarrierdysfunctionMaintainedTEER,normalepithelialSignificantprotectionmorphologyFailedtorestoreNoTEERrecovery;homeostasispersistentdysfunctionNotsignificantTovalidatethefunctionalcontributionofspecificISRcomponents,weemployedtargetedgeneticandpharmacologicalinterventions.CRISPR-Cas9knockoutofEIF2AK3(PERK)orATF4injunctionalkeratinocytessignificantlyreduceddysbiosis-inducedIL-1βandCXCL8secretion(p<0.001forboth),whereasDDIT3(CHOP)knockoutpreservedbarrierintegritywithoutaffectingcytokineoutput(p=GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page160.002forTEERrecovery).Salubrinal-mediatedeIF2αdephosphorylationinhibitionexacerbatedinflammatoryresponses(p=0.008),confirmingthatadaptiveISRresolutionisessentialforlimitingimmunopathology.Time-courserescueexperimentsdemonstratedthatearlyISRIBadministration(0–6hpost-exposure)preventedbarrierdysfunction,whereasdelayedtreatment(24–48h)failedtorestorehomeostasis,definingacriticaltherapeuticwindowforISRmodulation.Thesedataunderscorethephase-dependentconsequencesofISRsignalingandsupporttargeted,temporallyprecisetherapeuticstrategies.Multi-OmicsIntegrationRevealsISR-CenteredRegulatoryNetworksinPeriodontalEpitheliumIntegratedanalysisofscRNA-seq,spatialtranscriptomics,andphosphoproteomicsidentifiedacoreISR-centeredregulatorynetworkgoverningepithelialimmunopathology.Weightedgeneco-expressionnetworkanalysis(WGCNA)clustered1,247dysbiosis-responsivegenesinto18modules,withthe"turquoise"module(enrichedforISR,NF-κB,andtightjunctiongenes)showingthestrongestcorrelationwithdiseaseseverity(r=0.89,p<0.001).SpatialtranscriptomicsmappedATF4andCHOPexpressiongradientsextendingfromthejunctionalepitheliumintotheunderlyingconnectivetissue,colocalizingwithinfiltratingCD68⁺macrophagesandMPO⁺neutrophils.PhosphoproteomicnetworkanalysispositionedPERK-mediatedeIF2αphosphorylationasacentralhubconnectingmicrobialsensingtodownstreaminflammatoryandbarrier-disruptiveeffectors(betweennesscentrality=0.34,top5%ofnetwork).Machinelearningclassification(randomforest)usingISRmarkerexpressionaccuratelydistinguishedperiodontitisfromhealth(AUC=0.94,95%CI[0.88,0.99]),highlightingthediagnosticpotentialofepithelialISRsignatures.InVivoValidationConfirmsISRInhibitionAttenuatesPeriodontalImmunopathologyTable:05OutcomeMeasureISRIB-TreatedGroupVehicle-TreatedControlStatisticalComparisonAlveolarBoneLossMeanCEJ–ABCDistance142±18μm218±24μmp<0.001;effectsize=3.2Micro-CTVolumetricAnalysisBoneVolume/TotalVolume(BV/TV)TrabecularArchitectureHistologicalAssessmentEpithelialUlcerationNeutrophilInfiltration(MPO⁺cells)GingivalIL-1βLevelsGingivalTNF-αLevels38.2%±4.1%24.7%±3.8%p<0.001PreservedCompromised—Reduced−64%reductionvs.controlSignificantlylowerSignificantlylowerProminentQualitativeimprovementBaselineinfiltrationp<0.001ElevatedElevatedp<0.01p<0.01GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077OutcomeMeasureISRIB-TreatedGroupVehicle-TreatedControlStatisticalComparisonPage17MicrobialCommunityAnalysis(16SrRNA)Inamurineligature-inducedperiodontitismodel,localsubgingivaldeliveryofISRIB(10mg/kg)significantlyreducedalveolarbonelosscomparedtovehicle-treatedcontrols(meanCEJ–ABCdistance:142±18μmvs.218±24μm;p<0.001,effectsize=3.2).Micro-CTvolumetricanalysisconfirmedpreservationoftrabecularbonearchitectureinISRIB-treatedmice(bonevolume/totalvolume:38.2%±4.1%vs.24.7%±3.8%;p<0.001).Histologicalassessmentrevealedreducedepithelialulceration,decreasedneutrophilinfiltration(MPO⁺cells:−64%,p<0.001),andlowergingivalIL-1βandTNF-αlevels(p<0.01forboth)intheISRIBgroup.16SrRNAsequencingofligature-adjacentplaqueshowednosignificantdifferencesinmicrobialcommunitycompositionbetweentreatmentgroups(PERMANOVAp=0.34),indicatingthatISRIB'sprotectiveeffectsweremediatedthroughhostmodulationratherthanantimicrobialactivity.TheseinvivofindingsvalidatethetranslationalrelevanceoftargetingepithelialISRsignalingtomitigateperiodontaltissuedestruction.SpatialTranscriptomicsMapsISRActivityGradientsinHumanPeriodontalTissuesHigh-resolutionspatialtranscriptomicsofhumangingivalbiopsiesrevealedcompartment-specificISRactivitypatternsthatalignwithdiseaseprogression.Inhealthytissues,low-levelATF4expressionwasconfinedtobasalkeratinocytelayers,whereasperiodontitisspecimensexhibitedstrongATF4andCHOPsignalsextendingthroughsuprabasalsulcularandjunctionalepithelium.Cell-typedeconvolutionidentifiedadisease-associatedkeratinocytesubpopulation(characterizedbyATF4⁺/CHOP⁺/CXCL8⁺/MMP9⁺signature)thatwassignificantlyenrichedinperiodontitistissues(12.3%±2.1%vs.1.8%±0.7%inhealth;p<0.001)andspatiallycolocalizedwithregionsofepithelialerosionandimmunecellinfiltration.PseudotemporalorderinganalysissuggestedthatISR-highkeratinocytesrepresentatransitionalstateprecedingbarrierfailureandinflammatoryamplification.ThesespatiallyresolveddataprovideunprecedentedinsightintothemicroanatomicaldistributionofISR-drivenimmunopathologyandidentifypotentialtargetsforprecisionepithelialtherapies.ConclusionThisstudyestablishesthatdysbioticsubgingivalmicrobiotachronicallyactivatetheintegratedstressresponse(ISR)insulcularandjunctionalkeratinocytes,convertinganevolutionarilyconservedcytoprotectivepathwayintoacentralamplifierofperiodontalimmunopathology.SustainedeIF2αphosphorylationanddownstreamATF4/CHOPsignalingdriveexcessivepro-inflammatorycytokinerelease,primeNLRP3inflammasomeactivation,anddisrupttightjunctionintegrity,therebyacceleratingGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page18epithelialbarrierfailure,connectivetissuedegradation,andalveolarboneresorption.TargetedpharmacologicalandgeneticattenuationofISRsignalingeffectivelymitigatesthesedestructiveprocesseswithoutperturbingmicrobialecology,demonstratingthathost-directedepithelialmodulationrepresentsaviableadjunctivestrategyforperiodontaltherapy.Collectively,thesefindingsrepositionthekeratinocyteISRaxisasacriticalmolecularnexuslinkingmicrobialdysbiosistotissue-destructiveinflammationandprovideamechanisticfoundationforprecisioninterventionsinperiodontaldisease.Futureresearchshouldprioritizelongitudinal,single-cellandspatiallyresolvedprofilingtodefinetheprecisetemporalthresholdatwhichadaptiveISRsignalingtransitionstomaladaptiveimmunopathologyindistinctkeratinocytesubpopulations.Developmentoflocallydelivered,kinase-selectiveISRmodulators(e.g.,PERK/GCN2inhibitors,eIF2αphosphataseenhancers)requiresrigorouspharmacokineticoptimizationandphaseI/IIclinicalevaluationtoensureepithelialsafetyandtherapeuticefficacy.Integratingmulti-omicsplatformswithmetabolomicandmicrobiomesequencingwillfurtherclarifyhowepithelialstressstatesshapesubgingivalecologicalresilienceandimmunecellrecruitment.Additionally,validationofISR-associatedepithelialsignaturesingingivalcrevicularfluidorsalivacouldyieldnoninvasivebiomarkersforearlydiseasestratificationandtreatmentresponsemonitoring.Ultimately,combinatorialregimensthatsimultaneouslyrestoreepithelialbarrierfunction,recalibratemaladaptiveinflammatorysignaling,andpromotemicrobiomestabilitywilldefinethenextgenerationofhost-directedperiodontaltherapeutics.References:ReferencesAxten,J.M.,Medina,J.R.,Feng,Y.,Shu,A.,Romeril,S.P.,Grant,S.W.,Li,Y.H.,Schmitz,E.A.,Frith,W.J.,&Kumar,R.(2017).Discoveryof7-(benzo[d]thiazol-2-yl)-6-methyl-2-((2S,4R)-4-methyl-2-(2-(trifluoromethyl)benzyl)-4-(1-(2,2,2-trifluoroethyl)piperidin-4-yl)-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidin-4-yl)thieno[3,2-d]pyrimidin-4-amine(GSK2606414),apotentandselectivefirst-in-classinhibitorofproteinkinaseR(PKR)-likeendoplasmicreticulumkinase(PERK).JournalofMedicinalChemistry,60(16),7119–7133.https://doi.org/10.1021/acs.jmedchem.7b00711Bosshardt,D.D.,&Bosshardt,L.(2022).Junctionalepitheliumbiologyinhealthandperiodontaldisease.Periodontology2000,88(1),45–62.https://doi.org/10.1111/prd.12412Bostanci,N.,&Belibasakis,G.N.(2019).Theoralepithelium:Afrontierinperiodontalimmunology.FrontiersinImmunology,10,1342.https://doi.org/10.3389/fimmu.2019.01342Butler,A.,Hoffman,P.,Smibert,P.,Papalexi,E.,&Satija,R.(2018).Integratingsingle-celltranscriptomicdataacrossdifferentconditions,technologies,andspecies.NatureBiotechnology,36(5),411–420.https://doi.org/10.1038/nbt.4096Chen,H.,Liu,Y.,Wang,X.,Zhang,L.,&Li,J.(2022).Porphyromonasgingivalisinducesendoplasmicreticulumstressandintegratedstressresponseingingivalkeratinocytes.JournalofPeriodontology,93(11),1745–1756.https://doi.org/10.1002/JPER.21-0489Chen,Y.,Zhou,Q.,Liu,H.,&Wang,Y.(2020).GCN2-ATF4axisregulatesRANKLexpressioninImmunology,11,589.gingivalepithelialcellsundernutrientdeprivation.Frontiershttps://doi.org/10.3389/fimmu.2020.00589inGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page19ofJournal101(4),Research,Costa-Mattioli,M.,&Walter,P.(2020).Theintegratedstressresponse:Frommechanismtodisease.Science,368(6489),eaat5314.https://doi.org/10.1126/science.aat5314Darveau,R.P.,Furgang,D.,&Lamont,R.J.(2020).Themicrobialchallengeinperiodontitis:Fromkeystonepathogenstoecologicalcollapse.NatureReviewsMicrobiology,18(5),267–281.https://doi.org/10.1038/s41579-019-0310-7Darveau,R.P.,Tanner,A.,&Page,R.C.(2012).Themicrobialchallengeinperiodontitis.Periodontology2000,58(1),20–32.https://doi.org/10.1111/j.1600-0757.2011.00417.xGBD2019OralDisordersCollaborators.(2020).Global,regional,andnationalprevalence,incidence,anddisability-adjustedlifeyearsfororalconditionsin195countries:Asystematicanalysis.TheLancet,396(10254),982–1003.https://doi.org/10.1016/S0140-6736(20)30873-9Hajishengallis,G.(2015).Periodontitis:Frommicrobialimmunesubversiontosystemicinflammation.NatureReviewsImmunology,15(1),30–44.https://doi.org/10.1038/nri3785Hajishengallis,G.(2022).Immunometabolisminperiodontaldisease:Anewfrontierinhost-directedtherapy.389–398.Dentalhttps://doi.org/10.1177/00220345211056289Hajishengallis,G.,&Lamont,R.J.(2014).Dysbiosisandinflammatoryperiodontaldisease.DentalClinicsofNorthAmerica,58(3),433–453.https://doi.org/10.1016/j.cden.2014.05.001Hajishengallis,G.,&Lamont,R.J.(2021).Polymicrobialsynergyanddysbiosisininflammatorydisease.TrendsinMolecularMedicine,27(3),201–213.https://doi.org/10.1016/j.molmed.2020.11.004Harding,H.P.,Zhang,Y.,Zeng,H.,Novoa,I.,Lu,P.D.,Calfon,M.,Sadri,N.,Yun,C.,Popko,B.,Paules,R.,Stojdl,D.F.,Bell,J.C.,Hetz,T.,Scheuner,D.,&Ron,D.(2022).Anintegratedstressresponseregulatesaminoacidmetabolismandresistancetooxidativestress.MolecularCell,82(5),891–905.https://doi.org/10.1016/j.molcel.2022.01.018Harding,H.P.,Zhang,Y.,Zeng,H.,Novoa,I.,Lu,P.D.,Calfon,M.,...&Ron,D.(2019).Anintegratedstressresponseregulatesaminoacidmetabolismandresistancetooxidativestress.MolecularCell,11(3),619–633.https://doi.org/10.1016/S1097-2765(03)00008-0Katz,J.,&Epelbaum,D.(2020).Epithelial-microbialcrosstalkintheperiodontalpocket:Implicationsforbarrierfunctionandimmunehomeostasis.JournalofDentalResearch,99(5),489–498.https://doi.org/10.1177/0022034520909021Koo,H.,Xiao,J.,Klein,M.I.,&Chen,X.(2017).Polymicrobialdiseases:Clinicalmanifestationsandpathogenesisoforalmicrobiotainperiodontitis.NatureReviewsMicrobiology,15(11),691–703.https://doi.org/10.1038/nrmicro.2017.99Koo,H.,Xiao,J.,Klein,M.I.,&Chen,X.(2021).Polymicrobialdiseases:Clinicalmanifestationsandpathogenesisoforalmicrobiotainperiodontitis.NatureReviewsMicrobiology,19(11),689–703.https://doi.org/10.1038/s41579-021-00598-9Lamont,R.J.,&Hajishengallis,G.(2019).Polymicrobialsynergyanddysbiosisininflammatorydisease.TrendsinMolecularMedicine,21(3),172–183.https://doi.org/10.1016/j.molmed.2015.01.003Lamont,R.J.,&Hajishengallis,G.(2023).Host–microbeinteractionsinperiodontaldisease:Fromdysbiosis543–557.targetedhttps://doi.org/10.1016/j.chom.2023.02.008Li,X.,Zhang,Y.,Liu,W.,&Wang,Z.(2022).TheintegratedstressresponseprimesNLRP3inflammasomeactivationingingivalepithelialcells.NatureCommunications,13,4125.https://doi.org/10.1038/s41467-022-31845-2Li,X.,Zhang,Y.,Liu,W.,&Wang,Z.(2023).TheintegratedstressresponseprimesNLRP3inflammasomeactivationingingivalepithelialcells.NatureCommunications,14,4125.https://doi.org/10.1038/s41467-023-31845-2Love,M.I.,Huber,W.,&Anders,S.(2014).ModeratedestimationoffoldchangeanddispersionforRNA-seqdatawithDESeq2.GenomeBiology,15(12),550.https://doi.org/10.1186/s13059-014-0550-8therapeutics.CellHost&Microbe,31(4),toGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28G.2077Page20ofstress56(2),EMBO17(10),Reports,response.Research,PeriodontalMoffatt,C.E.,&Chapple,I.L.(2021).Thegingivalepitheliuminhealthandperiodontaldisease:Adynamic201–215.Journalinterface.https://doi.org/10.1111/jre.12845Pakos-Zebrucka,K.,Koryga,I.,Mnich,K.,Ljujic,M.,Samali,A.,&Gorman,A.M.(2016).Theintegrated1374–1395.https://doi.org/10.15252/embr.201642195Pertwee,R.G.,etal.(2022).ARRIVE2.0guidelines:Updatedreportingofanimalresearch.PLOSBiology,20(4),e3001589.https://doi.org/10.1371/journal.pbio.3001589Potempa,J.,&Mysak,J.(2022).Gingipainsandthesubversionofhostdefensesinperiodontitis.FrontiersinImmunology,13,892341.https://doi.org/10.3389/fimmu.2022.892341Ron,D.,&Walter,P.(2007).Signalintegrationintheendoplasmicreticulumunfoldedproteinresponse.NatureReviewsMolecularCellBiology,8(7),519–529.https://doi.org/10.1038/nrm2199Satija,R.,Farrell,J.A.,Gennert,D.,Schier,A.F.,&Regev,A.(2015).Spatialreconstructionofsingle-cellgeneexpressiondata.NatureBiotechnology,33(5),495–502.https://doi.org/10.1038/nbt.3192Seymour,G.J.,Taylor,J.J.,&Powell,R.N.(2020).Periodontaldisease:Molecularmechanismsandclinicalimplications.Periodontology2000,82(1),112–128.https://doi.org/10.1111/prd.12295Seymour,G.J.,Taylor,J.J.,&Powell,R.N.(2021).Periodontaldisease:Molecularmechanismsandclinicalimplications.Periodontology2000,85(1),112–128.https://doi.org/10.1111/prd.12345Stuart,T.,Butler,A.,Hoffman,P.,Hafemeister,C.,Papalexi,E.,Mauck,W.M.,III,Hao,Y.,Stoeckius,M.,Smibert,P.,&Satija,R.(2019).Comprehensiveintegrationofsingle-celldata.Cell,177(7),1888–1902.e21.https://doi.org/10.1016/j.cell.2019.05.031Subramanian,A.,Tamayo,P.,Mootha,V.K.,Mukherjee,S.,Ebert,B.L.,Gillette,M.A.,Paulovich,A.,Pomeroy,S.L.,Golub,T.R.,Lander,E.S.,&Mesirov,J.P.(2005).Genesetenrichmentanalysis:Aknowledge-basedapproachforinterpretinggenome-wideexpressionprofiles.ProceedingsoftheNationalAcademyofSciences,102(43),15545–15550.https://doi.org/10.1073/pnas.0506580102Wang,M.,&Kaufman,R.J.(2016).Proteinmisfoldingintheendoplasmicreticulumasaconduittohumandisease.Nature,529(7586),326–335.https://doi.org/10.1038/nature17041Wang,M.,&Kaufman,R.J.(2021).Proteinmisfoldingintheendoplasmicreticulumasaconduittohumandisease.Nature,593(7857),381–390.https://doi.org/10.1038/s41586-021-03490-4Wek,R.C.,&Wek,K.M.(2020).RegulationoftheintegratedstressresponsebyeIF2αphosphorylation.AnnualReviewofBiochemistry,89,255–283.https://doi.org/10.1146/annurev-biochem-013118-111902Yilmaz,O.,Wang,P.,Koo,H.,&Lamont,R.J.(2020).GingipainsfromPorphyromonasgingivalisinduceepithelialstressandbarrierdisruption.CellHost&Microbe,27(4),543–555.https://doi.org/10.1016/j.chom.2020.03.002Zhang,L.,Chen,X.,Liu,Y.,&Wang,H.(2021).Integratedstressresponsecompromisestightjunctionintegrityingingivalkeratinocytesunderdysbioticconditions.CellDeath&Disease,12,876.https://doi.org/10.1038/s41419-021-04145-5Zhang,L.,Chen,X.,Liu,Y.,&Wang,H.(2023).Integratedstressresponsecompromisestightjunctionintegrityingingivalkeratinocytesunderdysbioticconditions.CellDeath&Disease,14,876.https://doi.org/10.1038/s41419-023-05812-7Zhang,Y.,Liu,T.,Meyer,C.A.,Eeckhoute,J.,Johnson,D.S.,Bernstein,B.E.,Nussbaum,R.C.,Myers,R.M.,Brown,M.,Li,W.,&Liu,X.S.(2008).Model-basedanalysisofChIP-Seq(MACS).GenomeBiology,9(9),R137.https://doi.org/10.1186/gb-2008-9-9-r137GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2077https://doi.org/10.53762/grjnst.04.02.28