w w w . r e u m a t o l o g i a . c o m . b r
REVISTA
BRASILEIRA
DE
REUMATOLOGIA
Original
article
18
F-Fluorodeoxyglucose
positron
emission
tomography
and
serum
cytokines
and
matrix
metalloproteinases
in
the
assessment
of
disease
activity
in
Takayasu’s
arteritis
Anne
E.
D.
Arraes
a,
Alexandre
W.
S.
de
Souza
a,
Henrique
A.
Mariz
a,
Neusa
P.
Silva
a,
Ivone
C.
G.
Torres
b,
Paula
N.
V.
Pinto
b,
Eduardo
N.
P.
Lima
b,
Emilia
I.
Sato
a,∗aRheumatologyDivision,EscolaPaulistadeMedicina,UniversidadeFederaldeSãoPaulo(Unifesp),SãoPaulo,SP,Brazil bRadiologyDivision,HospitalA.C.Camargo,SãoPaulo,SP,Brazil
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received7August2014 Accepted1March2015
Availableonline9September2015
Keywords:
Cytokines
Matrixmetalloproteinases
Positronemissiontomographyscan Takayasu’sarteritis
a
b
s
t
r
a
c
t
Objective:To evaluate 18F-fluorodeoxyglucose (18F-FDG) uptake on positron emission
tomography–computedtomography(PET–CT)andserumlevelsofdifferentcytokinesand matrixmetalloproteinases(MMPs)inpatientswithTakayasuarteritis(TA)andassociations withdiseaseactivity.
Methods:Serumlevelsoftumornecrosisfactor-␣(TNF-␣),interleukin(IL)-2,IL-6,IL-8,
IL-12,IL-18,MMP-3andMMP-9weremeasuredin36TApatientsand36controls.Maximum standarduptakevalue(SUVmax)of18F-FDGinarterialwallswasdeterminedbyPET–CTscans.
TApatientswereclassifiedasactivedisease,inactivediseaseandpossibleactivedisease.
Results:SerumIL-6andMMP-3levelswerehigherinTApatientsthanincontrols(p<0.001). SerumIL-6washigherinpatientswithactivediseaseandinpatientswithpossibleactive diseasethanininactivedisease(p<0.0001).Patientswithactivediseasehadhigherserum TNF␣levelsthanpatientswithinactivedisease(p=0.049)whilepatientswithpossibleactive
diseasepresentedhigherIL-18levelsthanpatientswithinactivedisease(p=0.046).Patients withactivediseasehadhigherSUVmaxvaluesthanthosewithinactivedisease(p=0.042).By
receiveroperatingcharacteristic(ROC)curveSUVmaxwaspredictiveofactivediseaseinTA
andvalues≥1.3wereassociatedwithdiseaseactivity(p=0.039).SerumTNF-␣levelswere
higherinpatientswithSUVmax≥1.3than<1.3(p=0.045)andcontrols(p=0.012).SerumIL-6
levelswerehigherinpatientswithSUVmax≥1.3thanincontrols(p<0.001).Nodifferences regardingotherbiomarkerswerefoundbetweenTApatientsandcontrols.
Conclusions: HigherserumIL-6andTNF␣levelsaswellashigher18F-FDGuptakeinarterial
wallareassociatedwithactiveTA.
©2015ElsevierEditoraLtda.ThisisanopenaccessarticleundertheCCBY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).
∗ Correspondingauthor.
E-mail:eisato@unifesp.br(E.I.Sato).
http://dx.doi.org/10.1016/j.rbre.2015.08.007
Tomografia
por
emissão
de
pósitrons
com
18F-fluordesoxiglicose
e
citocinas
séricas
e
metaloproteinases
da
matriz
na
avaliac¸ão
da
atividade
da
doenc¸a
na
arterite
de
Takayasu
Palavras-chave:
Citocinas
Metaloproteinasesdamatriz Tomografiacomputadorizada ArteritedeTakayasu
r
e
s
u
m
o
Objetivo: Avaliaracaptac¸ãode18F-fluordesoxiglicose(18F-FDG)natomografiaporemissão depósitrons–tomografiacomputadorizada(PET–CT)eosníveisséricosdediferentes citoci-nasedametaloproteinasesdamatriz(MMP)empacientescomarteritedeTakayasu(AT)e associac¸õescomaatividadedadoenc¸a.
Métodos: Forammensuradososníveisséricosdofatordenecrosetumoral-␣(TNF-␣),
inter-leucina(IL)-2,IL-6,IL-8,IL-12,IL-18,MMP-3eMMP-9em36pacientescomATe36controles. Ovalorpadronizadodecaptac¸ãomáximo(SUVmax)de18F-FDGnasparedesarteriaisfoi
determinadoporexamesdePET–CT.OspacientescomATforamclassificadoscomotendo doenc¸aativa,doenc¸ainativaepossíveldoenc¸aativa.
Resultados: OsníveisséricosdeIL-6eMMP-3forammaisaltosempacientescomATdoque noscontroles(p<0,001).OsníveisséricosdeIL-6erammaiselevadosempacientescom doenc¸aativaeempacientescompossíveldoenc¸aativadoquenaquelescomdoenc¸a ina-tiva(p<0,0001).Ospacientescomdoenc¸aativaapresentaramníveisséricosmaiselevados deTNF-␣doqueospacientescomdoenc¸ainativa(p=0,049),enquantoosindivíduoscom
possíveldoenc¸aativaapresentarammaioresníveisséricosdeIL-18doqueospacientes comdoenc¸ainativa(p=0,046).Aquelescomdoenc¸aativaapresentarammaioresvaloresde SUVmaxdoqueaquelescomdoenc¸ainativa(p=0,042).DeacordocomacurvaROC,oSUVmax
eracapazdepredizeradoenc¸aativanaATevalores≥1,3estavamassociadosàatividadeda doenc¸a(p=0,039).OsníveisséricosdeTNF-␣forammaioresempacientescomSUVmax≥1,3
doquenaquelescomvalor<1,3(p=0,045)econtroles(p=0,012).OsníveisséricosdeIL-6 forammaiselevadosempacientescomSUVmax≥1,3doquenoscontroles(p<0,001).Não
foramencontradasdiferenc¸asemrelac¸ãoaoutrosbiomarcadoresentrepacientescomAT econtroles.
Conclusões: NíveisséricoselevadosdeIL-6eTNF-␣,bemcomoumamaiorcaptac¸ãode
18F-FDGnaparedearterial,estãoassociadosaATativa.
©2015ElsevierEditoraLtda.Este ´eumartigoOpenAccesssobumalicenc¸aCC BY-NC-ND(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Takayasu arteritis (TA) is a primary systemic vasculitis of unknownetiologythataffectslargearteries,mainlytheaorta and its mainbranches and less frequently pulmonaryand coronaryarteries.Thechronicgranulomatousinflammation occursinalllayersofthevesselwallandmayleadtostenosis, occlusion,dilationoraneurysmformation.1,2
Cell-mediatedautoimmunityplaysakeyroleinthe patho-genesisofTA.Immunohistochemicalstudiesoftheinfiltrating cellsintheaortictissuehaveshownmainlygamma-delta T-cells,CD4+andCD8+T-cells,NKcellsandmacrophages.3The
presenceofgranulomatousinflammationintheinternal elas-ticlayeristhemostcharacteristicpathologicfindingofTA. Theinflammatoryprocessbeginsinthevasavasorumanditis believedtobetriggeredbytheactivationofdendriticcellsand dendriticcell/T-cellinteractioninthevascular microenviron-mentoftheadventitiaoflargearteriesleadingtotheinduction ofaTh1response.4
ThedetectionofvascularinflammationinTApatientsis a major challenge in clinical practice, since up to 60% of asymptomaticpatientsdevelopednewangiographiclesions onsequentialarteriographicevaluation,and44%ofpatients
consideredtobeinremissionbyclinicalevaluationshowed histopathologicalevidenceofactiveinflammationonsurgical specimens.1 Duetotheevidenceofprogressionofvascular
damageinasymptomaticTApatients,additionalevaluation isnecessarytoguidetherapeuticdecisions.Nevertheless,to datethereisnoreliablesurrogateparametertodetect subclini-caldiseaseactivityinTApatients.Potentialbiologicalmarkers of inflammationand tissuedegradation,such ascytokines and metalloproteinases (MMPs) have been evaluated sepa-rately indifferent studies but some resultshave not been reproduced.5–7 Differentimagingtechniqueshavebeenused
toassesstheextentofarterialinvolvementinTA,amongthem
18F-fluorodeoxyglucose(18F-FDG)positronemission
tomogra-phy with computed tomography (PET–CT) scan can detect active arterial wallinflammation. Some studies have been promising8–10 whereasothershavefoundconflictingresults
withtheuseofPET–CTscanstoevaluatediseaseactivityin TA.11,12
Theaimsofthis studywere toevaluatetheintensityof
18F-FDGuptakeonPET–CTscansonarterialwallsand
quan-tifyserumlevelsofinterleukin-2(IL-2),IL-6,IL-8,IL-12,IL-18, tumornecrosisfactor-␣(TNF-␣),MMP-3andMMP-9inpatients
Materials
and
methods
Patientsandcontrols
Patients under regular follow-up at the Vasculitis Unit of theuniversityhospitalofUniversidadeFederaldeSãoPaulo (Unifesp)oratprivateofficesofrheumatologistswhoworkat Unifespwereconsecutivelyinvitedtoparticipateinthis cross-sectional study. They underwent clinical, laboratorial and imagingevaluationwithina20-dayperiod.Inclusioncriteria were the fulfillment of the American College of Rheuma-tology (ACR) classification criteria for TA,13 age above 18
years and the absence of malignancy,active infection and pregnancy.Thecontrolgroupscomprisedlaboratorycontrols (lab-controls)and PET–CTscan controls(PET-controls). The formergroupincluded36age-andgender-matchedsubjects withoutchronicinflammatoryorinfectiousdiseaseandthe lattergroupconsistedofsixhealthyindividualswho under-went a PET–CT scan, using the same protocol used by TA patients.Allsubjectssignedinformedconsentformapproved bytheInstitutionalEthicsCommitteesfromUnifespandAC CamargoHospital.
Clinicalandlaboratoryassessment
TheclinicalassessmentofTApatientswasperformedbytwo physiciansexperiencedinTAmanagement(AWSSandHAM) atroutinemedicalvisits.Diseaseactivitywasdefinedwhether theonsetorworseningofatleasttwoofthefollowingfeatures waspresent: (a)systemic featureswith noother identified cause;(b)theonsetoffeaturesofvascularischemiaor inflam-mation,suchaslimbclaudication,unequalorabsentpulse, bruit,vascularpain(carotidynia)orasymmetricblood pres-sure;(c)elevatedacutephasereactantsincludingerythrocyte sedimentationrate(ESR);(d)developmentofnewlesionsin previouslyunaffectedvascularterritories onserialvascular imagingevaluation.1TApatientspresentingabnormallevels
ofacutephasereactants(i.e.ESR≥40mm/hand/orserumCRP levels≥10mg/dL)withoutsignsandsymptomsofactiveTAor newangiographiclesionswereconsideredadistinctsubgroup namedaspossibleactivedisease.
Blood samples were collected from patients and lab-controls for cytokines, MMPs, ESR (Westergren) and CRP measurements. Serumsamples were separated and stored at −70◦C until tests were performed. The enzyme-linked
immunosorbentassay(ELISA)techniquewasusedtoquantify CRP(DiagnosticsSystemsLaboratories,EUA),IL-18(KitMed &BiologicLabCo,Japan),MMP-3andMMP-9(R&DSystems, EUA).Alltestswereperformedinduplicate.Themeasurement ofIL-2,IL-6,IL-8,IL-12andTNF-␣wasperformedbyLUMINEX
Millipexkits.
Imageassessment
PET–CTscans were acquired usinga GeminiPET–CT scan-ner (Philips) after at least a 6-h fasting period. Capillary glucose levels were checkedbefore scans and no one pre-sentedlevelsabove200mg/dLpriorto18F-FDGadministration.
Imageacquisition wasperformed 60minafterthe infusion
of0.154millicurie(mCi)/kgof18F-FDGandparticipantswere
scannedfromtheskulltoproximalthighs.Firstly,CTimages were obtainedwithoutthe infusionofintravenouscontrast using the following parameters: 120kV,120mAs, 0.75s per rotation, pitch1.5,5mmslicethicknessanda3mm recon-structioninterval.ThenPETscanwasacquiredduring2min and15sateachbedpositioninatotalof11bedpositions. PET-controlsubjectshadundergonethesameprotocolandtheir scanswereretrievedfromthearchive.AllPET–CTscanswere performedatACCamargoHospitalandimageswere evalu-atedbyaradiologist(PNVP)andanuclearmedicinephysician (ICGT)who wereunawareofclinical andlaboratory assess-mentsofTApatients.
A semi-quantitative assessment of 18F-FDG uptake was
done at using the standard uptake value (SUV). The SUV wascalculated dividingthemaximumtissueconcentration bythe totalinjecteddose of18F-FDGperbody weight.The
regionofinterest(ROI)wasmanuallyplacedonarterywallsof thefollowingsites:vertebral,internalcarotid,subclavianand commoncarotidarteries,pulmonaryartery,brachiocephalic trunk, aortic arch, ascending, descending and abdominal aorta,celiactrunk,superiorandinferiormesentericarteries, renalandiliacarteries.ThehighestvalueofSUVfoundineach arterywasrecordedandonlythehighestvalueonthewhole PET–CTscan(SUVmax)wasusedforstatisticalanalysis.
Statisticalanalysis
Statisticalanalysiswasperformedwiththesoftware Statisti-calPackagefortheSocialSciences(SPSS)version17.0(Chicago, IL).Categoricaldatawaspresentedastotalnumberand per-centage, and numerical data as median (range) or mean (standard deviation) as appropriate. The Shapiro–Wilk test wasusedtotestthenormalityofcontinuousvariables. Com-parisonsregardingnumericalvariableswereperformedwith Mann–WhitneyUtestorStudent’sttestfortwogroupsorwith Kruskal–Wallistestorone-wayANOVAtestforthreeormore groups.TheMann–WhitneyUtestwithBonferroni’scorrection wasusedasaposthoc test.Valuesofp<0.05were consid-eredsignificant whilepvaluesbetween0.10and 0.05were consideredasstatisticaltendency.
SUVmax valuesforthe diagnosis of disease activity was
evaluatedbytheROC(receiveroperatingcharacteristic)curve andtheYoudenindexwasusedtoassessthebestcutoff val-ues.ResultsoftheROCcurvewereexpressedinareaunder thecurve,95%confidenceinterval(95%CI),positive predic-tivevalue,negativepredictivevalue,accuracy,sensitivityand specificityforcutoffpointsofSUVmax.Correlationsbetween
numericalvariableswereperformedbySpearman’stest.The presenceofactivediseaseinTAdeterminedbythecutoffof SUVmaxwascomparedtodiseaseactivitydeterminedby
clini-calevaluationusingFisher’sexacttest.Statisticalsignificance wasconsideredforp<0.05.
Results
Patientsandcontrols
Table1–DemographicanddiseasefeaturesofTApatientsevaluatedinthisstudy.
Variables Activedisease(n=14) Inactivedisease(n=11) Possibleactivedisease(n=11) p
Age,years 35.0(22.0–54.0) 32.0(24.0–68.0) 32.0(21.0–56.0) 0.818
Females,n(%) 14(100.0) 9(81.8) 10(90.9) 0.262
TimesincefirstTAsymptoms,months 72.0(24.0–216.0) 85.0(23.0–372.0) 118.0(9.0–207.0) 0.800 Timesincediagnosis,months 45.5(2.0–216.0) 66.0(17.0–292.0) 58.0(1.0–240.0) 0.628 ESR,mm/h 20.00(5.00–115.00) 11.00(1.00–26.00) 26.00(7.00–70.00) 0.059 SerumCRPlevels,mg/dL 18.17(0.10–99.05) 1.53(0.17–7.77) 78.13(8.16–91.89) <0.0001
CRP,C-reactiveprotein;ESR,erythrocytesedimentationrate.
Dataarepresentedasmeanandstandarddeviationorasmedianandrange.
considered withinactive disease and11 (30.6%)had possi-ble activedisease.Table 1describes demographicfeatures, timesincethe onset ofsymptoms attributabletoTA,time sincediagnosis and acutephase reactantsin subgroupsof TApatients.PatientswithactivediseasehadhigherESRand serum CRP levels than patients with inactive disease. TA patientswithpossibleactivediseasehadsignificantlyhigher serumCRPlevelsthan patientsinremissionandatrendto havehigherESRthanpatientsinremission(Table1).Atthe timeofassessment,21patientswereonsteroidsand immu-nosuppressive agents, three patients only on steroids, six weretreatedonlywithanimmunosuppressiveagentandsix other patients were not receiving any therapy for TA. The medianprednisonedailydosewas12.5mg(5.62–27.50).The followingimmunosuppressiveagentswereusedbypatients: methotrexate (50.0%), mycophenolate sodium (11.1%), aza-thioprine (8.3%), and cyclophosphamide (5.6%). Only one patientusedetanercept.
Thelab-controlgroupcomprised33 womenand 3men, withamedianageof34.0(20–68)years.Alllab-controlsdidnot presentanymedicalconditionandwerenotunderany med-icaltherapy.ThePET-controlgroupconsistedofsixhealthy individuals(fourwomen,twomen)withmedianageof32.5 (28–45)years.
Cytokinesandmetalloproteinases
Table 2 shows serum levels ofcytokines and MMPs in TA
patientsandlab-controls.TApatientspresentedhigherIL-6 levels(p<0.001)andhigherserumMMP-3levels(p<0.001)and atendencyforhigherTNF-␣levels(p=0.069)thanlab-controls.
No significant differences were found regarding serum
levelsofIL-2,IL-8,IL-12,IL-18andMMP-9whencomparing TApatientsandlab-controls(Table2).
SerumcytokineandMMPslevelsinTApatientswithactive disease,patientswithinactivediseaseandpatientswith pos-sibleactivediseaseare showninTable3.SerumIL-6levels were higherinpatientswithactivedisease andinpatients withpossibleactivediseasecomparedtowithpatientswith inactivedisease(p<0.0001)(Fig.1).Althoughatendencyfor differenceswasfoundregardingserumTNF␣andIL-18levels
amongTAsubgroups,whenthosesubgroupswereanalyzed separately,TApatientswithactivediseasehadsignificantly higherserumTNF␣levelsthanpatientswithinactivedisease
(p=0.049) while patients with possible active disease pre-sentedhigherserumIL-18levelsthanpatientswithinactive disease(p=0.046).
CorrelationsamonginflammatorymarkersinTApatients
IL-6levelscorrelatedwithESR(rho=0.475;p=0.005)andwith CRPlevels (rho=0.673;p<0.001).CRPlevels andESRvalues (rho=0.585; p<0.001) were significantly correlated as well. TNF-␣ levelscorrelatedwithIL-6 (rho=0.365;p=0.029),IL-8
(rho=0.346;p=0.039),aswellaswithCRPlevels(rho=0.370;
p=0.026).Furthermore,serumIL-2andIL-12levelswere corre-lated(rho=0.529,p=0.001).Nocorrelationswerefoundamong othercytokinesandMMPs.
Medicaltherapy,cytokines,metalloproteinasesandacute
phasereactants
MMP-3 levels were higher in TA patients using steroids than in those without steroids (45.05±26.96ng/mL vs.
Table2–SerumlevelsofcytokinesandmetalloproteasesinTApatientsandcontrols.
Markers TApatients(n=36) Lab-controls(n=36) p
IL-2,pg/mL 0.36(0.00–23.38) 0.25(0.00–21.87) 0.710
IL-6,pg/mL 7.55(0.17–76.22) 1.74(0.17–16.21) <0.0001a
IL-8,pg/mL 4.83(1.88–17.92) 4.49(2.02–22.02) 0.327
IL-12,pg/mL 0.00(0.00–46.39) 0.00(0.00–11.97) 0.908
IL-18,pg/mL 151.71(0.00–463.26) 121.63(0.00–745.22) 0.130
TNF-␣,pg/mL 5.64(1.91–15.28) 4.26(1.41–12.89) 0.056
MMP-3,ng/mL 27.00(6.00–102.70) 12.05(4.30–75.50) <0.0001a
MMP-9,ng/mL 495.55(183.70–2338.80) 452.15(221.20–2044.00) 0.457
IL,interleukin;MMP,matrixmetalloproteinase;TNF,tumornecrosisfactor.
Table3–SerumlevelsofcytokinesandmetalloproteasesinTApatientswithactivedisease,inactivediseaseandwith possibleactivedisease.
Variables Activedisease(n=14) Inactivedisease(n=11) Possibleactivedisease(n=11) p
TNF␣,pg/mL 5.93(3.84–10.71) 4.16(1.91–15.28) 6.76(3.69–9.23) 0.079
IL-2,pg/mL 0.19(0.00–1.57) 1.12(0.00–12.04) 0.44(0.00–23.38) 0.354 IL-6,pg/mL 9.15(0.65–76.22) 2.48(0.17–10.80) 8.48(1.25–37.56) 0.003a
IL-8,pg/mL 5.47(2.83–17.92) 4.53(1.88–10.56) 4.61(2.74–8.82) 0.368
IL-12,pg/mL 0.00(0.00–2.22) 0.00(0.00–12.56) 0.00(0.00–46.39) 0.587
IL-18,pg/mL 183.58±129.05 119.96±57.98 246.20±147.29 0.059
MMP3,ng/mL 22.40(6.00–94.90) 26.30(9.30–102.70) 31.10(7.10–84.90) 0.682
MMP9,ng/mL 515.10(208.40–2338.80) 424.20(183.70–1422.50) 491.30(274.40–1160.40) 0.547
IL,interleukin;MMP,matrixmetalloproteinase;TNF,tumornecrosisfactor.
Continuousdataarepresentedasmedianandrangeorasmeanandstandarddeviation. a Statisticallysignificantvalues.
13.11±6.36ng/mL; p<0.001)and apositive correlation was observedbetweenMMP-3levels and dailyprednisonedose (rho=0.463; p=0.023) (Fig. 2). No associations were found amongsteroidsuse,dailyprednisonedose, immunosuppress-ivetherapy and levels ofMMP-9,cytokines or acutephase reactants(datanotshown).
PET–CTscanandbiomarkers
MedianSUVmaxvalueswerehigherinTApatientsthanin
PET-controls[1.57(0.87–3.04)vs.0.99(0.67–1.23);p=0.001]andin patientswithactivediseasecomparedwiththoseinremission [1.97(1.19–3.04)vs.1.19(0.87–2.59);p=0.015].However,no sig-nificantdifferencesregardingSUVmaxcouldbefoundbetween
TA patients with active disease and those with possible activedisease[1.97(1.19–3.04)vs.1.58(1.00–2.72);p=0.324]or betweenpatientswithpossibleactivediseaseandthosewith inactivedisease[1.58(1.00–2.72)vs.1.19(0.87–2.59);p=0.212]. Furthermore,patientswithinactivediseasepresentedhigher
Possible active disease Inactive disease
Active disease .00
20.00 40.00
p=0.001
p=0.584 o
o
o o
p=0.008
pg/ml
60.00 80.00
Fig.1–IL-6levelsinpatientswithactivedisease,inactive diseaseandpossibleactivedisease.SerumIL-6levelswere significantlyhigherinpatientswithactivediseaseandin patientswithpossiblediseaseactivitythaninpatients withinactivedisease.Nosignificantdifferencescouldbe foundbetweenTApatientswithactivediseaseandpatients withpossibleactivedisease.
SUVmax values than PET-controls [1.19 (0.87–2.59) vs. 0.99
(0.67–1.23);p=0.049].Fig.3illustratesthePET–CTfindingsina TApatientwithactivedisease.
TA patients on immunosuppressive therapy presented lower median SUVmax values than patients without those
agents [1.41 (0.87–3.04) vs. 2.57 (0.96–3.00); p=0.044]. How-ever, no differences in median SUVmax values were found
in patients with and without steroids [1.48 (0.87–3.04) vs. 2.14(0.96–3.00);p=0.127]aswellasnocorrelationwasfound between SUVmax and daily prednisone dose (rho=0.233;
p=0.274). Moreover, no correlations were found between SUVmax valuesand ESR(rho=0.081; p=0.647)orCRP levels
(rho=0.139; p=0.419)and betweenSUVmax valuesand
lev-elsofanycytokineorMMPsevaluatedinthisstudy(datanot shown).
ROCcurveanalysisshowedthevalueofSUVmaxasa
pre-dictorofactivediseaseinTA(AUC=0.703;95%CI=0.534–0.832;
p=0.043). The best cutoff points obtained for SUVmax
val-ues (withtheir respective sensitivity and specificity) were:
Daliy prednisone dose, mg
MMP-3, ng/ml
0 0 10 20 30 40 50 60
120 100 80
60 40 20
Fig.3–RepresentativePET–CTscanimagesfromapatientwithTakayasuarteritisandactivedisease.
PET–CTscanimagesofa32-years-oldfemalepatientwithclinicallyactivedisease:(A)fusionimageincoronal
reconstructionwith18F-FDGuptakeinascendingaorta,(B)imagesofPETscanincoronalplanewith18F-FDGuptakeinthe
abdominalandascendingaorta;(C)fusionimageinaxialsectionshowing18F-FDGuptakeinascendingaortaandright
pulmonaryartery,(D)fusionimageinaxialsectionwith18F-FDGuptakeintheabdominalaorta.
1.23,(93%and 45%),1.29 (86%and50%) and1.83 (57%and 73%).MoreTApatientspresentingactivediseasebasedonNIH criteriahadSUVmax≥1.3onarterialwallswhencomparedto
thosewithSUVmax<1.3(p=0.039)(Table4).Thiscutoffvalue
yieldedapositivepredictivevalueof52.0%,anegative predic-tivevalueof78%andanaccuracyof63.8%foractivediseasein TA.PatientswithSUVmax values≥1.3presentedhigher
TNF-␣(p=0.015)andIL-6levels(p=0.036)incomparisontothose
withSUVmaxvalue<1.3andlab-controls(Fig.4AandB).No
sig-nificantdifferenceswerefoundregardinglevelsofIL-2,IL-8,
IL-12,IL-18,MMP-3,MMP-9,ESRandCRPregardingtheSUVmax
cutoffvalueof1.3(Table4).
Discussion
Thisisthefirststudyevaluatingthemajorityofbiomarkers of inflammatoryactivity already reported inthe literature, including several cytokines and MMPs as well as 18F-FDG
uptakeinlargearteriesonPET–CTscan inTApatients.TA
Table4–Comparisonofdiseaseactivityparameters,cytokinesandmatrixmetalloproteinasesinTApatientsbasedon SUVmaxcutoffvalueof1.3.
Variables SUVmax≥1.3(n=23) SUVmax<1.3(n=13) p
Activedisease,n(%) 12(52.2) 2(15.4) 0.039a
ESR,mm/h 19.00(5.00–115.00) 14.00(1.00–70.00) 0.139
CRP,mg/dL 24.56(0.10–99.05) 5.23(0.17–82.34) 0.096
TNF␣,pg/mL 6.76(3.56–15.28) 4.37(1.91–9.23) 0.015a
IL-2,pg/mL 0.44(0.00–23.38) 0.05(0.00–8.50) 0.484
IL-6,pg/mL 8.48(0.43–76.22) 4.46(0.17–37.56) 0.036a
IL-8,pg/mL 5.15(1.88–17.92) 4.53(2.16–10.56) 0.553
IL-12,pg/mL 0.00(0.00–46.39) 0.00(0.00–5.06) 0.130
IL18,pg/mL 164.60(0.00–424.01) 132.05(60.95–463.26) 0.987
MMP-3,ng/mL 26.90(6.00–94.90) 27.10(7.10–102-70) 0.542
MMP-9,ng/mL 499.80(183.70–2338.80) 461.60(283.20–1442.40) 0.564
CRP,C-reactiveprotein,ESR,erythrocytesedimentationrate;IL,interleukin;MMP,matrixmetalloproteinase;SUV,standarduptakevalue;TNF, tumornecrosisfactor.
TNFα, pg/mL
IL-6, pg/mL
SUV≥1.3
SUV≥1.3
SUV<1.3
SUV<1.3
Lab-controls
Lab-controls 15
A
B
10p=0.015
p<0.0001
p=0.036 p=0.075 p=0.002
p=0.802
5
0
80
60
40
20
0
Fig.4–SerumTNF␣andIL-6levelsinpatientswith
SUVmax≥1.3,patientswithSUVmax<1.3andlab-controls. SerumTNF␣(A)andIL-6(B)levelsweresignificantlyhigher
inTApatientspresentingSUVmax≥ 1.3comparedto patientswithSUVmax<1.3andlab-controls.Nodifference
couldbefoundregardingserumTNF␣andIL-6levels
betweenpatientswithSUVmax<1.3andlab-controls.
patientspresentedhigherSUVmax valuesof18F-FDGuptake
onlargearteries byPET–CTscansand higherserum levels ofIL-6andMMP-3thancontrols.Moreover,SUVmaxvaluesof 18F-FDGuptakeonlargearteries,serum IL-6andTNF␣
lev-elswerehigherinTApatientspresentingactivediseasewhen comparedtothoseconsideredwithinactivedisease.Patients withpossibleactivedisease(i.e.onlyhighacutephase reac-tantswithoutsignsandsymptomsofactiveTA)presenthigher serumIL-6andIL-18levelsthanpatientswithinactivedisease. However,nosignificantdifferenceswereobservedregarding SUVmaxvaluesinpatientswithpossibleactivedisease
com-paredtothosewith activediseaseand those withinactive disease.
Althoughbeingararedisorder,TAoftencauseshigh mor-bidity due to the progression of vascular lesions, and to thelackofreliableparameters todetectdisease activity to allowanefficaciousintervention.Studiesevaluatingsurrogate
markersandimagingmethodstoassessdiseaseactivityinTA patientshaveprovidedinconsistentresults.Thereasonsfor thisincludethelackofagoldstandardtodetectdisease activ-ityandtheinclusionofsmallnumberofTApatientsinvarious studies.
Corroboratingpreviousstudies5,6wefoundassociationof
serum IL-6 levelswithboththe disease statusand disease activityinTA.DifferentlyfromtheresultsofParketal.,6serum
TNF␣levelswerehigherinpatientswithactivediseasethan
thoseinremissionbutthedifferenceshowedonlyatendency tobehigheramongTApatientsthaninlab-controls(p=0.056). Serumlevelsofothercytokineswere notdifferentbetween TApatientsandcontrolsandtheywerenotusefulto differen-tiateTApatientswithactiveandinactivedisease.Although, apreviousstudyhadfoundanassociationbetweendisease activity andserumlevelsofIL-18inTApatients,6 wecould
notfindsignificantdifferencesinIL-18levelsbetweenpatients and controls,orbetweenTApatientswithactiveand inac-tivedisease.Indeed,wefoundhigherserumIL-18levelsinTA patientswithpossibleactivediseasecomparedtocontrolsand thismayindicatethatthosepatientsmaypresentsubclinical inflammation.SimilarlytoTrypathyetal.,wefoundno differ-encesinserumIL-2levelsbetweenTApatientsandcontrols. Nevertheless,theyobservedalowerpercentageofIL-2 produc-ingCD3+T-cellsinpatientswithactivediseaseincomparison topatientswithinactivediseaseandcontrols.14Theroleof
IL-12asasurrogatemarkerofdisease activityinTAisstill controversial.Inonestudy,similarlevelsofserumIL-12were foundbetweenpatientsandcontrolswhileinanotherstudy, plasmaIL-12levelswerehigherinpatientswithactivedisease incomparisontothosewithinactivediseaseandcontrols.6,15
Inthepresentstudy,IL-12levelsweresimilarinTApatients and controlsandnoassociationwithdiseaseactivity could befound.AlthoughIL-8levelswerehigherinTApatientsthan incontrolsandassociatedwithdiseaseactivityinonestudy,16
wecouldnotfindanydifferencesregardingIL-8levelsbetween patientsandcontrols.
In asinglestudy,higher MMP-3and MMP-9levelswere associatedwithactivediseaseinTApatients,witha subse-quentdecreasefollowingdiseasecontrol.7Inourstudy,only
MMP-3 levels were higher inpatients than in controlsbut no difference related to disease activity was found. MMP-3 levelswere higheramong patientsusing steroids witha positive correlation betweenMMP-3 levels and daily pred-nisonedose.Theassociationbetweensteroiddailydoseand MMP-3levelswasalsoreportedinpatientswithrheumatic diseases,17 including a recent study in patientswith TA.18
Sharif etal.19 founda53% increaseinpro-MMP-3levelsin
patients with rheumatoid arthritis using prednisone, even amongstpatientspresentingadecreaseinother inflamma-toryparameters.However,themechanisminvolvedinMMP-3 elevationassociatedwithsteroidsuseisstillunclear.
Initial studies with PET–CT scans evaluating disease activity inTAshowed promisingresults.10,20 Morerecently,
to detect active disease in TA.21 However, another study
hasraised questions about the usefulness ofthis method, sincethereisno SUVvaluedefinedasnormalforthe ves-selwall.11Ameta-analysisincludingsixstudiesfoundthat
PET–CTscanhadamoderatevaluetoevaluatedisease activ-ityinTA.Thepooledsensitivityandspecificity were70.1% (95%CI:58.6–80.0)and77.2%(95%CI:64.2–87.3),respectively. Authors considered that PET–CT scan was not suitable to beused asthe sole methodto evaluatedisease activity in TAbutitmaybeadditionalvaluetocurrentclinical assess-ment. Heterogeneityamong studies is a limitation of this meta-analysis.22
Several studies have considered the SUV values useful in the diagnosis and prognosis for cancers.23–25
Neverthe-less, this imaging technique is still a matter of debate as longasalargevariabilityofSUVvalueshasbeen observed amongseveral institutes,thus raisingthe needtocalibrate equipments and standardize parameters for data acquisi-tionandprocessinginordertoobtaincomparableresults.26
SUVmax valuesbecomemorereliablewhenusedas
param-eters withinthe same institute, under the same technical conditions, especially in the comparison of serial imaging studies.
Inthisstudy,PET–CTscanswereperformedunderfasting conditionsandcapillarybloodglucosewascheckedbefore18
F-FDGadministrationtoexcludethepossibilityoffalse-negative resultsdue tohyperglycemia. Although,the 18F-FDGin TA
might betaken up mostly byinflammatory cells in vessel walls,theinfluenceofbloodglucoselevelshasnotbeenstill establishedinthiscontext.27Rabkin etal.28havedescribed
false-negativeresultsinpatientswithdifferenttypesofcancer whenbloodglucoseexceeded180mg/dL,butnotinpatients withinfectiousorinflammatoryconditions.
Henesetal.studiedtheuseofPET–CTinpatientswithlarge vesselvasculitis,includingthreepatientswithTAandfound SUVmaxvaluesbetween1.6and6.8withinarterialwalls.Inthis
study,SUVmaxvaluesrangedfrom2.5to5.8inTApatientswith
activedisease.Amongeightpatientswithsurgicallytreated solidtumorsusedascontrols,SUVmaxvaluesrangedfrom1.4
to2.3.8
AnotherstudyevaluatedPET–CTscansin20patientswith large vessel vasculitis including 3 patients with TA. The SUVmaxcutoffvalueof1.78hadthebestperformanceforthe
diagnosisofalargevesselvasculitiswithsensitivityand speci-ficityof,respectively,65%and80%byvisualscale,and90% and45%bytheSUVmax.Thecontrolgroupwasconstitutedby
patientstreatedforthyroidcancer.12
SUVmax values in the above-mentioned studies were
slightlyhigherthanwhatwefoundforTApatients. Techni-caldifferencesinPET–CTscanprotocolsmaybeahurdleto compareourresultswithdifferentstudies.Furthermore,our studyincludedonlyTApatientswithameanageof36years whereas inthe above-mentioned studies,8,12 mostpatients
had giant cell arteritis witha higher mean age (62 years). Ourcontrolgroup consistedofhealthysubjects, instead of cancerpatients.Theinfluenceofageintheincreaseof18
F-FDGhasbeendemonstratedinoneretrospectivestudy29and
itmayoccurinpartduetoatherosclerosis.Indeed,thisfact mightreducePET–CTscansspecificityinTApatients,sincethe prevalenceofatherosclerosisisincreasedinthosepatients.30
Arnaudetal.foundlowsensitivityandspecificityofPET–CT scantodetect diseaseactivityinTApatients.Theydidnot findanyassociationwitheitherinflammatorymarkersornew lesions onserialMRIangiographies.Theyusedvisualscale and quantitative evaluation to assess 18F-FDG uptake and
foundastrongcorrelationbetweenbothmethods.11 In
con-trast,Leeetal.havealsoevaluatedthePET–CTscansinTA patientsusingthevisualscaleandSUV.Theyfoundan asso-ciation between18F-FDGuptakein vesselwalland disease
activityinbothassessments.31
Using theSUVmax tomeasure18F-FDGuptake,wefound
higher valuesofSUVmax inTApatientswithactivedisease
comparedtothosewithinactivedisease.Henceinourstudy, SUVmax seemed to be predictive of disease activity in TA.
Patientsusingimmunosuppressiveagentshadlowerarterial SUVmaxvaluescomparingwiththosewithoutthese
medica-tions.Thisfindingindicatesasuppressiveeffectonvascular inflammationbroughtbythe useoftheseagentsandadds anotherargumentinfavoroftheusefulnessofPET–CTscans forthedetectionofthevascularinflammationinTA.Inline with thisfinding, Leeet al.31 havedescribed adecrease in
18F-FDGuptakeduringthe follow-upofeightpatientsafter
controlling disease activity with immunosuppressive treat-ment.
We found SUVmax values similar to those found by
Kobayashiet al.,despitetechnicaldifferencesinstudy pro-tocols.Thecutoffvalueof1.3wasthesameinbothstudies andwasbasedonthehighestSUVmaxvaluefoundincontrols.
However,thesensitivityandspecificityfordetectionofdisease activitywere86%and50%,respectively,inourstudy,which arelowerthanthosefoundbytheseauthors.Thisremarkable difference maybeduetodifferent criteriausedforclinical evaluationinbothstudies.Theyconsideredclinicalremission onlywhenpatientswereatleast2yearswithoutsteroid.10
Ourstudyalsoanalyzedtheassociationbetweenacutoff value ofSUVmax and serum levelsofcytokines and MMPs.
PatientswithSUVmax≥1.3hadhigherlevelsofTNF-␣andIL-6.
WealsofoundanassociationbetweenSUVmax≥1.3and dis-easeactivity.TheanalysisofbiomarkersusingthisSUVmax
cutoffvaluehighlightstheconsistentresultsachievedfrom clinical evaluationofdisease activity inTA.Thesignificant correlationbetweenserumIL-6levelsandotherinflammatory markersindicatestheconsistencyofthesefindings.
Main limitations of this study include the sample size, thecross-sectionaldesignandthelackofagoldstandardto evaluateinflammatoryactivityinTA,sinceeventhewidely usedNIHcriteriahavenotbeenvalidatedyet.Moreover,the weakness oftheNIHcriteriaishighlightedbythefactthat TApatientswithhighacutephasereactantswhodonot ful-filltheNIHcriteriaforactivediseaseactuallypresenthigher serumlevelsofIL-6andIL-18thanTApatientsconsideredwith inactive disease.Suchpatientsshouldbefollowedupmore carefullyinordertodetectclinicallysignificantactivedisease early.However,thelownumberofpatientsinthesubgroups ofinactivepatientsandpatientswithpossibleactivedisease mayhaveimpairedcomparisonsamonggroupsand assump-tions,especiallyregardingIL-18levelsshouldbetakenwith caution.
Ourresultssuggestthat theintensityof18F-FDGuptake
processandthatPET–CTscanseemstobeausefulmethod todetectdisease activityinTA,especiallytoexcludeactive disease indoubtful cases.A prospectivestudy witha long termfollow-upwouldbenecessarytoobservechangesinthe SUVmax valuesaftertreatmentoreventodetectthe
devel-opment of new vascular lesions (e.g. vascular stenosis or aneurysms)insitespresentinghigh18F-FDGuptake.IL-6also
appearstobeapromisingparameterofdiseaseactivityinTA thatshouldbeassessedinalongitudinalstudyaswell.The rel-evanceofIL-6residesinthefactthatitcanalsobeapotential therapeutictargetinTA.32
Funding
TheresearchhadfinancialsupportbyFAPESP(São PauloRe-searchFoundation),grantnumber2008/54787-3toSatoEI.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgements
TheauthorsthankACCamargoHospital.
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1. KerrGS,HallahanCW,GiordanoJ,LeavittRY,FauciAS,Rottem M,etal.Takayasu’sarteritis.AnnInternMed.1994;120: 919–29.
2. JohnstonSL,LockRJ,GompelsMM.Takayasu’sarteritis:a review.JClinPathol.2002;55:481–6.
3. SekoY,MinotaS,KawasakiA,ShinkaiY,MaedaK,YagitaH, etal.Perforin-secretingkillercellinfiltrationandexpression ofa65-kDheat-shockproteininaortictissueofpatientswith Takayasu’sarteritis.JClinInvest.1994;93:750–8.
4. ArnaudL,HarocheJ,MathianA,GorochovG,AmouraZ. PathogenesisofTakayasu’sarteritis:a2011update. AutoimmunRev.2011;11:61–7.
5. NorisM,DainaE,GambaS,BonazzolaS,RemuzziG. Interleukin-6andRANTESinTakayasu’sarteritis:aguidefor therapeuticdecisions?Circulation.1999;100:55–60.
6. ParkMC,LeeSW,ParkYB,LeeSK.Serumcytokineprofiles andtheircorrelationswithdiseaseactivityinTakayasu’s arteritis.Rheumatology(Oxf).2006;45:545–8.
7. MatsuyamaA,SakaiN,IshigamiM,HiraokaH,KashineS, HirataA,etal.Matrixmetalloproteinasesasnoveldisease markersinTakayasu’sarteritis.Circulation.2003;108: 1469–73.
8. HenesJC,MüllerM,KriegerJ,BalletshoferB,PfannenbergAC, KanzL,etal.[18F]FDG-PET/CTasanewandsensitiveimaging methodforthediagnosisoflargevesselvasculitis.ClinExp Rheumatol.2008;26:S47–52.
9. MellerJ,GrabbeE,BeckerW,VosshenrichR.ValueofF-18FDG hybridcameraPETandMRIinearlyTakayasuaortitis.Eur Radiol.2003;13:400–5.
10.KobayashiY,IshiiK,OdaK,NariaiT,TanakaY,IshiwataK, etal.AorticwallinflammationduetoTakayasu’sarteritis imagedwith18F-FDGPETcoregisteredwithenhancedCT.J NuclMed.2005;46:917–22.
11.ArnaudL,HarocheJ,MalekZ,ArchambaudF,GambottiL, GrimonG,etal.Is(18)F-fluorodeoxyglucosepositronemission tomographyscanningareliablewaytoassessdiseaseactivity inTakayasu’sarteritis?ArthritisRheum.2009;60:
1193–200.
12.LehmannP,BuchtalaS,AchajewN,HaerleP,EhrensteinB, LighvaniH,etal.18F-FDGPETasadiagnosticprocedurein largevesselvasculitis–acontrolled,blindedre-examination ofroutinePETscans.ClinRheumatol.2011;30:37–42.
13.ArendWP,MichelBA,BlochDA,HunderGG,CalabreseLH, EdworthySM,etal.TheAmericanCollegeofRheumatology 1990criteriafortheclassificationofTakayasu’sarteritis. ArthritisRheum.1990;33:1129–34.
14.TripathyNK,GuptaPC,NityanandS.HighTNF-alphaandlow IL-2producingTcellscharacterizeactivediseasein
Takayasu’sarteritis.ClinImmunol.2006;118:154–8.
15.VermaDK,TripathyNK,VermaNS,TiwariS.Interleukin12in Takayasu’sarteritis:plasmaconcentrationsandrelationship withdiseaseactivity.JRheumatol.2005;32:2361–3.
16.TripathyNK,SinhaN,NityanandS.Interleukin-8in Takayasu’sarteritis:plasmalevelsandrelationshipwith diseaseactivity.ClinExpRheumatol.2004;22:S27–30.
17.RibbensC,MartinyPorrasM,FranchimontN,KaiserMJ, JasparJM,DamasP,etal.Increasedmatrix
metalloproteinase-3serumlevelsinrheumaticdiseases: relationshipwithsynovitisandsteroidtreatment.Ann RheumDis.2002;61:161–6.
18.IshiharaT,HaraguchiG,TezukaD,KamiishiT,InagakiH, IsobeM.DiagnosisandassessmentofTakayasu’sarteritisby multiplebiomarkers.CircJ.2013;77:477–83.
19.SharifM,SalisburyC,TaylorDJ,KirwanJR.Changesin biochemicalmarkersofjointtissuemetabolismina randomizedcontrolledtrialofglucocorticoidinearly rheumatoidarthritis.ArthritisRheum.1998;41:1203–9.
20.WebbM,ChambersA,AL-NahhasA,MasonJC,MaudlinL, RahmanL,etal.Theroleof18F-FDGPETincharacterising diseaseactivityinTakayasu’sarteritis.EurJNuclMedMol Imaging.2004;31:627–34.
21.KarapolatI,KalfaM,KeserG,Yalc¸inM,InalV,Kumanlio ˘gluK, etal.ComparisonofF18-FDGPET/CTfindingswithcurrent clinicaldiseasestatusinpatientswithTakayasu’sarteritis. ClinExpRheumatol.2013;31:S15–21.
22.ChengY,LvN,WangZ,ChenB,DangA.18-FDG-PETin assessingdiseaseactivityinTakayasu’sarteritis:a meta-analysis.ClinExpRheumatol.2013;31:S22–7.
23.OkadaM,ShimonoT,KomeyaY,AndoR,KagawaY,Katsube T,etal.Adrenalmasses:thevalueofadditional
fluorodeoxyglucose-positronemission
tomography/computedtomography(FDG-PET/CT)in differentiatingbetweenbenignandmalignantlesions.Ann NuclMed.2009;23:349–54.
24.BerghmansT,DusartM,PaesmansM,Hossein-FoucherC, BuvatI,CastaigneC,etal.Primarytumorstandardized uptakevalue(SUVmax)measuredonfluorodeoxyglucose
positronemissiontomography(FDG-PET)isofprognostic valueforsurvivalinnon-smallcelllungcancer(NSCLC):a systematicreviewandmeta-analysis(MA)bytheEuropean LungCancerWorkingPartyfortheIASLCLungCancer StagingProject.JThoracOncol.2008;3:6–12.
25.ChunEJ,LeeHJ,KangWJ,KimKG,GooJM,ParkCM,etal. Differentiationbetweenmalignancyandinflammationin pulmonaryground-glassnodules:thefeasibilityofintegrated (18)F-FDGPET/CT.LungCancer.2009;65:180–6.
27.DiederichsCG,StaibL,GlattingG,BegerHG,ReskeSN.FDG PET:elevatedplasmaglucosereducesbothuptakeand detectionrateofpancreaticmalignancies.JNuclMed. 1998;39:1030–3.
28.RabkinZ,IsraelO,KeidarZ.Dohyperglycemiaanddiabetes affecttheincidenceoffalse-negative18F-FDGPET/CTstudies inpatientsevaluatedforinfectionorinflammationand cancer?Acomparativeanalysis.JNuclMed.2010;51:1015–20.
29.YunM,YehD,AraujoLI,JangS,NewbergA,AlaviA.F-18FDG uptakeinthelargearteries:anewobservation.ClinNucl Med.2001;26:314–9.
30.SeyahiE,UgurluS,CumaliR,BalciH,SeyahiN,YurdakulS, etal.AtherosclerosisinTakayasu’sarteritis.AnnRheumDis. 2006;65:1202–7.
31.LeeKH,ChoA,ChoiYJ,LeeSW,HaYJ,JungSJ,etal.Therole of(18)F-fluorodeoxyglucose-positronemissiontomography intheassessmentofdiseaseactivityinpatientswith Takayasuarteritis.ArthritisRheum.2012;64:866–75.