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NEUROINFLAMMATION AND AUTISM SPECTRUM DISORDERS

NAACONFERENCEMAY2019

MICHAELWELICE,MD.FAAP.FMAPS

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Neuroinflammation

•  Neuroinflammationisinflammationofthenervoustissuewhichmaybeinitiatedinresponsetoavarietyortriggersincludinginfection,traumaticbraininjury,toxicmetabolitesorautoimmunity

•  IntheCNSwhichincludesthebrainandthespinalcord,microgliaaretheresidentinnateimmunecellsthatareactivatedinresponsetothesetriggers

•  TheCNSistypicallyanimmunologicallyprivilegedsitebecausetheperipheralimmunecellsaregenerallyblockedbythebloodbrainbarrier,aspecializedstructurecomposedofastrocytesandendothelialcells.

•  CirculatingperipheralimmunecellsmaycrossacompromisedBBBandencounterneuronsandglialcellsexpressinghistocompatibilitycomplexmoleculeswhichperpetuateanimmuneresponse

•  ThisresponseisdesignedtoprotecttheCNSfromtheinfectiousoffendingagentsbutmaybetoxicandcreatewidespreadinflammationaswellasfurthermigrationofleukocytesthroughtheBBB

• NeuroinflammationwasonceaclearlydefinedtermdenotingpathologicalimmuneprocesseswithintheCNS.

• Thefourhallmarksofperipheralinflammation:CNSinjuries,stroke,injuryorinfection

• Recentlythedefinitionofneuroinflammationhasrelaxedtothepointthatitisoftennowassumedtobepresentwhenevenonlyasingleclassicalhallmarkofinflammationwasmeasured.

• Unexpectednon-classicalimmuneactionsofimmunemediatorsandcellsintheCNSintheabsenceofpathologyhaveincreasedthelikelihoodthathomeostaticandadaptiveimmuneprocessesintheCNSwillbemistakenforneuroinflammation.

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What is neuroinflammation in Autism?

•  Embryonicneurogenesisistheprocessofgeneratingneurons,thefunctionalunitsofthebrain

•  Dysregulationofneurogenesisduetoadverseintrauterineenvironmentsuchasinfection,toxicantexposure,environmentalandfoodtriggershasemergedasakeymechanismunderlyingmanyneurodevelopmentaldisorderssuchasASD

•  AhallmarkfeatureofbraindisorderssuchasASDisneuroinflammationwhichcaneitherpromoteorinhibitneurogenesisdependingonthecontextofbrainmicroenvironment

•  Brainpathologyissuggestiveofongoingneuroinflammationorencephalitisindifferentregionsofthebrain**

•  *Dysregulationofneurogenesisbyneuroinflammation:keydifferencesinneurodevelopmentalandneurologicaldisorders.FanLWNeuralRegenRes2017,Mar

•  **Kern,JK,GeierDA,GeierMRetal.FrontCellNeurosci2016Jan

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Shared brain connectivity issues, symptoms and comorbidities in ASD, ADHD and Tourette Syndrome

•  EvidencesuggeststhatASD,ADHDandTShavesimilarneuropathology

•  Theymaybelongtoabroaderspectrumofneurodevelopmentalillnessesbasedonlong-rangeunderconnectivityandshort-rangeoverconnectivityrelatedtoneuronalinsult

• Neuronalinsultfromneurotoxicity,neuroinflammation,excitotoxicty,sustainedmicroglialactivation,proinflammatorycytokines,toxicexposureandoxidativestress.

Kern,Geieretal.BrainConnect2015

What is Oxidative Stress? Injurytocellsfromtoxicbyproductsofnormalcellularchemistryresultingfromaninsufficientresponsebythebody’sprotectivemechanism

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Causes of Neuroinflammation

• Environmentalallergies• Foodallergies/intolerance

• Infections• Toxicantexposures

• Anychangesinthestateofinflammationinthebrainduringnormaldevelopmentcanpotentiallyleadtoanincreaseinsusceptibilitytoneurologicalandneurodegenerativediseases

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Inflammation

•  Acute Inflammation •  Early response to injury/infection, lasts days •  Swelling, redness, heat, pain at site •  Beneficial, leads to elimination of infection and tissue

healing •  Innate cells and mediators

•  Chronic Inflammation •  Late or sustained response to intracellular pathogens or

self antigens (autoimmunity) •  Harmful, results in tissue destruction •  Adaptive and innate cells and mediators •  Often LOCAL at specific sites

Hypothesis: inflammatory events in pregnancy such as response to infection, may disrupt the normal expression of immune molecules during critical stages of neural development and thereby contribute

to the risk for neurodevelopmental disorders such as ASD •  Immunemoleculessuchascytokinesandchemokinesproducedbymicrogliainthebrainarecriticalfornormalbraindevelopment

•  Singleviralinfectionorinjectionofviralmimetictopregnantmicesignificantlyandpersistentlyimpactsoffspringimmuneandnervoussystemfunction

•  Studiesinhumansandnon-humananimalmodelshavesupportedthehypothesisthatongoingdisruptedimmunemoleculeexpressionand/orneuroinflammationcontributestoasignificantsubsetofASD

•  Ingeneticallysusceptibleindividuals,environmentalriskfactorscombineorsynergizetocreateatippingthresholdpointfordysfunction

•  StudiesshowingalinkbetweenmaternalimmuneactivationandASD-likeoutcomesinoffspringinvolvediverseenvironmentalfactorsbeyondinfectionincludingtoxinexposures,maternalstressallofwhichimpactinflammatoryorimmunepathways

•  *Beyondinfection-maternalimmuneactivationbyenvironmentalfactors,microglialdevelopmentandrelevanceforASDsBilboSDetal.ExpNeurol2017July8

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Maternal Inflammation

•  Environmentalinsults,infectionormalnutritionimpactbraindevelopmentandisassociatedwithneurodevelopmentaldisordersinchildren

•  Maternalviralorbacterialinfectionshavebeencharacterizedasdisruptorsofbrainshaping•  Imbalanceofessentialfattyacids,especiallypolyunsaturatedfattyacids(PUFAs)areobservedinASDpatientsandthosewithADHDandschizophrenia.

•  Omega3PUFAsarepowerfulimmunomodulatorsthatexertanti-inflammatorypropertiesaffectingthefetalbrainandmicrobiota*

•  Maternalstressandterbutaline,usedtoarrestpre-termlaborresultedinseverebehavioralsymptoms,astrogliosisandspontaneousrecurrentconvulsiveseizuresin45%andepileptiformspikesin100%ofratsstudied.Thisdemonstratesthatnotasingleteratogenbutacombinationofteratogensmaycausecomorbidautismandepilepsy.**

•  **Bercum,etal.JNeurosci2015Dec•  *MadoreC,etal.NeuralPlast2016

Lipopolysaccharides

•  Systemiclipopolysaccharide-inducedneuroinflammationaffectsmicrogliaandearlyneuraldevelopmentaleventsinrats

•  Exposureasearlyasday3postnatallyleadstoarobustmicrogliaactivationbothproandanti-inflammatoryphenotypes

•  Anti-inflammatorymarkerswereupregulatedinmultiplewhiteandgraymatterstructuresassociatedwithmarkeddecreaseinnaturallyoccurringapoptosis,butanincreaseincellproliferationinthesubventricularzoneandthedentategyrusofhippocampus,increaseinoligodendrocytelineagepopulation

•  LPSexposedratsexhibitedsignificantimpairmentsincommunicativeandcognitivefunctions

•  ThissuggestsapossibleroleoftheM2-likeanti-inflammatorymicroglialactivationinabnormalneuraldevelopmentinASDbehavioralimpairments*

•  *Pang,Yetal.,PlosOne2016Oct

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Immune dysfunction in Neuroinflammation

• ASDindividualshavealteredimmuneresponsesinTcells,Bcells,monocytes,naturalkillercellsanddendriticcells

• ASDindividualshavealterationsinimmunoglobulinsandincreasedautoantibodies

• ASDindividualshaveelevatedperipheralcytokinesandchemokinesassociatedwithneuroinflammation

•  *Biorklund,etal,ActalNuerobiolExp2016

Potential Target of Inflammation

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MAST CELLS

What are Mast Cells? •  Exacerbateautoimmunityviaalterationofinnateandadaptiveimmunitythatprotectordamagethehost

•  TypeIhypersensitivityresponses•  TypeIIIautoimmunediseases–Arthusreaction,SLE,RA•  ActivationbyIgEandinflammatorymediators•  Allergy,Atopicdermatitisandallergicrhinitis•  Inflammatoryconditions–rapidreleaseofTNF,IL-6andmastcellproteases

•  Resistbacterialinfection–sepsis,lymphaticdrainage•  Preventparasiteinfection•  Exacerbateatherosclerosis•  Promotecancerprogression

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MAST CELL ACTIVATION DISORDER AND ASD OVERLAP •  allergicsymptomsthatallergistsayarenotallergies•  intestinalinflammation•  intestinalslowdownpossiblyresultingindistention•  breakdownofthegut-bloodbarrier,i.e.leaky-gut•  highfeversandredsbotchyhives•  breakdownoftheblood-brainbarrier•  braininflammation•  neurotoxinsinthebrain•  reducedneuralconnectivity•  "brainfog"•  paininsensitivity•  reducedlearningability•  seizures•  andevenmore

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Mast cells in neuroinflammation and brain disorders

• Microgliaandastrocytesaremajorpathogeniccomponentswithinthisprocesswhichrespondtoproinflammatorymediatorsreleasedfrommastcells

• Mastcellsresideinthebrainandareanimportantsourceofinflammatorymolecules

•  Interactionswithglialcellsandneuronsresultinthereleaseofmediatorssuchascytokines,proteasesandreactiveoxygenspecies

•  Duringneuroinflammation,excessivelevelsofthesemediatorscaninfluenceneurogenesis,neurodegenerationandBBBpermeability

•  Theyhavebeenimplicatedinneuronaldisorderssuchascerebralischemia,TBI,neuropathicpain,multiplesclerosis,AD,migraine,autismanddepression

•  *HendriksenEetal.NeurosciBiobehavRev2017Aug

Treatment of Mast Cell Activation

• H1andH2antagonists• Mastcellstabilizers•  Ketotifen•  Luteolin,Quercetin•  Epinephrine•  Steroids•  Leukotrieneantagonist•  Montelukast

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Histamine signaling in ASD

• Histaminergicsystemhasacriticalroleincognition,sleepandotherbehaviors

• Histamineisaneurotransmitterandanimmunemodulator•  ImplicatedinmanyneurologicaldisorderswhichsharecomorbiditywithASD,includingTourette’ssyndrome.

• Mediatesneuroinflammation,whichisheightenedinASD,• RNAsequencingfocusedgenesetofHSgenes:HDC,HNMT,HRH2,HRH3andHRH4whichwassignificantlyaltered

•  *AlteredexpressionofhistaminesignalinggenesinASD.Wright,Cetal.TranslPsychiatry2017,May

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HISTAMINE IN THE GI TRACT

HIGHLEVELSINTHEGUTIMMUNOREGULATORIN:

FOODALLERGY

FOODPOISONINGHISTAMINEINTOLERANCE

IRRITABLEBOWELSYNDROMEINFLAMMATORYBOWELDISEASE

SomalinskaS,JutalM.CrameriR,O’MahoneyL,HistamineandGutMucosalImmuneRegulation,Allergy2014Mar,69.pp.273-81

.

AlthoughnoCNSdiseaseentityhasbeenassociateddirectlytobrainhistaminedysfunctionuntilnow,theH(3)receptorisrecognizedasadrugtargetforneuropathicpain,sleep-wakedisorders….andcognitiveimpairmentassociatedwithattentiondeficithyperactivitydisorderCNSNeurosciTher.2011Dec;17(6):620-8.doi:10.1111/j.1755-5949.2010.00212.x.Epub2010Nov22.HistaminepharmacologyandnewCNSdrugtargets.

TiligadaE1,KyriakidisK,ChazotPL,PassaniMB

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Immune Modulation in the Gut

•  At birth - digestive tract of humans is minimally colonized.

•  Colonised by microbes within the first few days of life

•  At first, predominantly bifidobacteria (breast fed infants).

•  With the introduction of other foods, a diverse microbial population develops in the gastrointestinal tract.

•  By now, of all the cells in a human body, the overwhelming majority are non-human.

CourtesyPatrickHanaway,MD

FreeRadicBiolMed.2014Mar;68:122-33.doi:10.1016/j.freeradbiomed.2013.11.008.Epub2013Nov22.Roleoftheentericmicrobiotainintestinalhomeostasisandinflammation.KobozievI1,ReinosoWebbC1,FurrKL1,GrishamMB2.

•  Ourcoexistencewiththegutmicrobiotarepresentsadynamicandmutuallybeneficialrelationshipthatisthoughttobeamajordeterminantofhealthanddisease.

•  Failuretoproperlyregulateintestinalmucosalimmunityisthoughttoberesponsiblefortheinflammatorytissueinjuryobservedintheinflammatoryboweldiseases(IBD;Crohndisease,ulcerativecolitis)

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Microbiota, immune and nervous systems

•  Studiesinvestigatingthegut-brainaxisdemonstrateacriticalroleforthegutmicrobiotainorchestratingbraindevelopmentandbehaviorandtheimmunesystemisanimportantregulatoroftheseinteractions

•  Intestinalmicrobesmodulatethematurationandfunctionoftissue-residentimmunecellsintheCNS

•  Microbesinfluencetheactivationofperipheralimmunecellswhichregulateresponsestoneuroinflammation,braininjury,autoimmunityandneurogenesis

•  Inappropriateantigentraffickingthroughanimpairedintestinalbarrierfollowedbypassageoftheseantigensorimmune-activatedcomplexesthroughapermissiveblood-brainbarriercanleadtoASD

•  ASDbrainhasalteredexpressionofgenesassociatedwithBBBintegritycoupledwithincreasedneuroinflammationandpossiblyimpairedgutbarrierintegrity**

•  Thusboththegutmicrobiotaandimmunesystemareimplicatedintheetiopathogenesisormanifestationofneurodevelopmental,psychiatricandneurodegenerativediseasessuchasASD

•  *FungTCetal.,NatNeurosci2017Feb

•  **Fiorentino,Metal.MolAutism2016,Nov

Qureshi, Towards a systems level

understanding of the nervous system and its,

Trends in Neurosciences, Vol 36, Issue 11, November 2013

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Enteric short chain fatty acids

•  Preorperinatalinfection,hospitalization,earlyantibioticexposurewhichaltersgutmicrobiotamaybepotentialrisksinASD

•  Entericshortchainfattyacids(SCFAs)presentindietandproducedbyopportunisticgutbacteriafollowingfermentationofdietarycarbohydratesmaybeenvironmentaltriggersinASD

•  Propionicacidandcarnitinemetabolism•  majorSCFAproducedbyASD-associatedbacteriaegclostridia,bacteroidesandalsoacommonfoodpreservativecanproducereversiblebehavioral,electrographic,neuroinflammatory,metabolicandepigeneticchangescloselyresemblingthosefoundinASDwhenadministeredtorodents

•  MajoreffectsoftheseSCFAsmaybethroughalterationofmitochondrialfunctionviathecitricacidcycle

•  Hypothesis:ASDsareproducedbypreorpostnatalalterationsinintestinalmicrobiotainsensitivesub-populations*

•  *McFabe.MicrobEcolHealthDis2015May

Short chain and polyunsaturated fatty acids as markers in autism

•  Fattyacidsareessentialdietarynutrientswhichprovidepolyunsaturatedfattyacids(PUFAs)forthegrowthandfunctionofnervoustissue.

•  SCFAsarederivedfromthemicrobiomelinkedtoeffectsonthegut,brainandbehavior

•  ReducedlevelsofPUFAs,importantduringbraindevelopmentareassociatedwithimpairmentsincognitiveandbehavioralperformance

•  Omega-3fattyacidssuchaseicosapentaenoic(EPA)anddocosahexaenoicacids(DHA)areinvolvedinneurogenesis,neurotransmissionandprotectionfromoxidativestress

•  Omega-ePUFAsantagonizeomega-6PUFA(arachidonicacid)inducedprostaglandin–E2(PGE2)formation

El-Ansary,etal.LipidsHealthDis.2014

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Toxicant exposure

•  Numerousstudiessupportanimportantroleforheavymetalexposure,particularlymercuryintheetiologyofASD

•  Youngchildrenmaybeparticularlysusceptibletoairpollution-inducedneurotoxicity

•  Prenatalexposuremaycauseorcontributetodevelopmentaldisabilitiesandbehavioralabnormalities

•  Recentstudieshavefoundassociationsbetweenexposurestotraffic-relatedairpollutionandASD

•  Higherlevelsofneuroinflammationandsystemicinflammation•  Gene-environmentinteractionsmayplayaroleindeterminingindividualsusceptibilitytoairpollutiondevelopmentalneurotoxicity

•  *LiH,etal.BiolTraceElemRes2017,May

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Organophosphate insecticides

•  Organophosphateinsecticidesie.ChlorpyrifosarewidelydiffusedenvironmentaltoxicantsassociatedwithneurobehavioraldeficitsandincreasedriskofASDinchildren

•  Oxidativestressanddysregulatedimmuneresponsesareimplicatedinorganophosphateneurodevelopmentaleffects

•  Gestationalexposureappearstostrengthensomeautistic-liketraitsthusresultingindelayedandlong-lastingalterationsinspecificpathwaysrelevanttoASD*

•  *DeFelice,etal.JofNeuroinflammation2016Jun

Lead

•  LeadhasbeenidasoneofthemainneurotoxicantsactingasenvironmentaltriggersidentifiedwithneuroinflammationandautoimmunityinASD.

•  Levelsofbloodleadweremeasuredin60ASDand60Healthycontrolmatchedchildrenbetween5and12yearsrecruitedfromlowlead–pollutedareas.

•  BloodleadlevelsweresignificantlyhigherinASD(>10mcg/dl)comparedtoHC.

•  ThereweresignificantandpositivecorrelationsbetweenlevelsofleadandvaluesoftheCARS(Childhoodautismratingscale)andIQ

•  PatientswithASDshowingincreasedleadlevelshadhigherfrequencyofanti-ribosomalantibodies*

•  *Mostafaetal.,MetabBrainDis2016Oct

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Mercury

•  Microtubuledegeneration•  Long-rangeaxondegeneration•  Dendriticovergrowth•  Neuroinflammation•  Microglial/astrocyticactivation•  Brainimmuneresponseactivation•  Oxidativestressandlipidperoxidation•  Decreasedreducedglutathioneandelevationofoxidizedglutathione

Kern,Geieretal.ActaNeurobiolExp2012

•  Mitochondrialdysfunction•  Disruptionofcalciumhomeostasis•  Inhibitionofglutamicaciddecarboxylase(GAD)activity

•  DisruptionofGABAergicandglutamatergichomeostasis

•  InhibitionofIGF-1,methioninesynthaseactivity

•  Impairmentofmethylation•  Decreaseincerebral/cerebellarbloodflow•  Increasepro-inflammatorycytokinelevelsinthebrain(TNF-a,IL-1B,Il-8)

•  NF-kappaBactivation

Mercury

•  NeurotoxicantthatispotentiallyoneofthetriggersforASDasitinducesneuroinflammationandsubsequentreleaseofneuropeptides.

•  LevelsofNeurokininAandbloodmercuryweremeasuredin84childrenwithASDbetween3-10yearsofageand84matchedHC

•  TherewasapositivelinearrelationshipbetweentheCARSandbothserumneurokininAandbloodmercuryintheASDkidscomparedwiththeHC.78%ofASDpatientshadelevatedmercurylevelsand55%increaseinserumneurokininA*

•  *Mostafaetal.MetabBrainDis2016Jan

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Aluminum

• Aknownneurotoxin• Hasnoplaceinthehumanbody•  Iscontainedinalmostallvaccinesinextremelyhighlevels

Parabens Butylparabenisapreservativeusedinfood,drugsandcosmetics

Neurotoxicandpotentiallyestrogenicactivity

ThoughtocontributetoASDandlearningdisabilities

Leadstoincreasedoxidativestress,decreasedreducedglutathioneandelevatedoxidizedglutathione,mitochondrialdysfunctionandneuroinflammation,increasedpro-inflammatorycytokinesinthebrain(TNF-a,IL-6,IL1-beta)

Disturbanceofenergycarriers:AMP,ATP

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Electromagnetic and radiofrequency radiation exposures - EMF/RFR

•  Deficienciesofantioxidantssuchasglutathione•  Peroxidizedcellmembranelipids•  Mitochondrialdysfunction•  Immunesystemdisturbances•  Increasedoxidativestress;freeradicaldamagecompromisingBBBandbrainperfusion

Clinicalmanifestations:•  Changesinbrainandautonomicnervoussystemelectrophysiologicalfunction•  Sensoryprocessingdisorders•  Seizures•  Sleepdisturbance

Herbert,M.Pathophysiology,2013June

GABAergic/glutamatergic imbalance

• AutoimmunityimmunedysfunctionandneuroinflammationareetiologicalmechanismsofASD

• RegressionisassociatedbetweenreducedGABAlevel,neuroinflammationandglutamateexcitotoxicity.

•  FeverorhyperthermiamayalterglutamatelevelsinthebrainhavinganimpactonsymptomsofASD

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HOWTOTREATNEUROINFLAMMATON

•  Findaphysicianwhounderstandsthepresentingproblemsandwhoiswillingtolisten

•  Properpatientevaluationwhichincludesacompletehistoryandphysicalexam

•  Completehistoryincludes:ConceptionandpregnancyhistoryDeliveryandbirthhistoryIllnessesGastrointestinalsymptomsRespiratoryillnessesSkinproblemsSleephistoryNeurologicalsymptomsEnvironmentalhistoryFamilyHistory

•  Orderappropriatelabtests;blood,urine,stool,MRIofbrain,EEG–24-48hourtest,SPECTscan

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•  Interpretationoflabworkisessentialtounderstandinghowtotreatthepatient

• Developatreatmentplanbasedonwhichtriggersappeartobeinvolved.Isitgenetic?Environmental?Infections?Food?

• Goodfollowupiscriticaltounderstandingiftreatmentplansareeffectiveornot.

• Remember–EVERYCHILDISNOTTHESAMEANDONESIZEFITSALLISNOTTRUE!

AUTISM SPECTRUM DISORDERS ARE TREATABLE AND RECOVER IS POSSIBLE •  don’tsetanendpointintimewhereyouexpectyourchildtobeatalevelofrecovery.

•  Timetoseeimprovementinvarioussymptomsvariesfrompatienttopatient

•  Itisn’tasprint,it’samarathon•  Surroundyourselfwithsupportivemedicalpersonnel,therapists,teachersandlovingfamilymembers

•  Don’twastetimewithpeoplewhotellyouthereisnothingyoucandoorthosewhocriticizeyouandmakeyoufeelinadequateasaparentorcaregiver

•  Askquestions!!•  Don’tstopuntilyougetanswersthatmakesense!!

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THANKYOU