Dimethylarginines correlate to common carotid artery wall layer dimensions and cardiovascular risk factors in pregnant women with/without preeclampsia: A group comparative study

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Dimethylarginines

correlate

to

common

carotid

artery

wall

layer

dimensions

and

cardiovascular

risk

factors

in

pregnant

women

with/without

preeclampsia:

A

group

comparative

study

Tansim

Akhter

a,

*

,

Gerhard

Wikström

b

,

Marita

Larsson

a

,

Ulf

Bondesson

c,d

,

Mikael

Hedeland

c,d

,

Tord

Naessen

a

DepartmentofWomen’sandChildren’sHealth,ObstetricsandGynecology,Sweden

b

DepartmentofMedicalSciences,Cardiology,Sweden

c

NationalVeterinaryInstitute(SVA),DepartmentofChemistry,EnvironmentandFeedHygiene,Sweden

d

DepartmentofMedicalChemistry,AnalyticalPharmaceuticalChemistry,UppsalaUniversity,Sweden

ARTICLE INFO Articlehistory:

Received22October2020

Receivedinrevisedform4January2021 Accepted9January2021

Keywords: Preeclampsia Dimethylarginines Cardiovasculardisease Highfrequencyultrasound Commoncarotidarteryintima/media thicknessratio

Subclinicalatherosclerosis

ABSTRACT

Objectives:Asymmetric-andsymmetricdimethylarginines(ADMA,SDMA)areelevatedincardiovascular disease(CVD).Preeclampsiaisapregnancy-speciﬁcsyndromeandisanindependentriskfactorfor subsequentCVD.AimsweretoinvestigatewhetherADMA,SDMAlevelsandL-arginine/ADMAandL

-arginine/SDMAratiosduringpregnancyandtheirchangesfrompregnancytopostpartumareassociated to arterial wall layer dimensions and cardiovascular risk factors in women with and without preeclampsia.

Studydesign:DimethylarginineswereanalyzedbyLC–MS,andthecommon-carotid-artery(CCA)intima andmediathicknesseswereestimatedusing22-MHznon-invasiveultrasonographyinwomenwith preeclampsia (cases=48) and normal pregnancies (controls=58) in similar gestational age, with reassessment one-yearpostpartum. A thick intima, thin mediaand high intima/mediaratio (I/M) indicatesalesshealthyarterialwall.

Results:Themedianageofcasesandcontrolswas30years.Duringpregnancy,womenwithpreeclampsia hadhigherplasmaADMA,SDMAandlowerL-arginine/ADMAandL-arginine/SDMA(allp<0.01)than women with normal pregnancies. Further, ADMA, SDMA, L-arginine/ADMA and L-arginine/SDMA correlatedtointimathickness(rs=0.33/0.33/0.33/0.35andp<0.01),I/M(rs=0.26/0.28/0.22/0.26

andp<0.05)andmeanarterialpressure(MAP)(rs=0.43/0.42/0.39/0.40andp<0.0001).Changesin

ADMA,SDMAandL-arginine/SDMAfrompregnancytopostpartumcorrelated tochangesinintima thickness (rs=0.22/0.32/-0.21 and p<0.05/<0.01/<0.05),I/M (rs=0.22/0.31/0.08and p<0.05/<0.01/

=0.43) and MAP (rs=0.31/0.53/-0.25 and p<0.01/<0.001/<0.05). No correlations were found for

conventionalCCAintima-media-thickness.

Conclusions: Dimethylarginines were associated to signs of adverse effects on arterial wall layer dimensionsandcardiovascularriskfactorsinwomenwithandwithoutpreeclampsia,duringpregnancy andtotheirchangesfrompregnancyuptoone-yearpostpartum.

Introduction

Dimethylarginines, asymmetric (ADMA) and symmetric (SDMA) are naturally occurring amino acids in plasma and generated by degradation of methylated protein as a result of

protein arginine methyltransferase [1]. Dimethylarginines is a directendogenousinhibitorofnitricoxidesynthase(NOS),which leadstodecreasednitricoxide(NO)synthesis.Dimethylarginines mayalsoreduceNOsynthesisindirectlybyinhibitingthecellular uptake of the NO precursor L-arginine [1]. NO is a potent vasodilator,generatedinthevesselendotheliumfromL-arginine bytheNOSenzyme[1].Thus,elevateddimethylarginineslevelsare associatedwithdecreasedNOlevels,whichleadstoendothelial dysfunction and development of atherosclerosis [2,3]. Plasma levels of dimethylarginines are increased in patients with cardiovasculardisease(CVD)[4,5].

*Corresponding author at: Department ofWomen’s and Children’sHealth,

SectionofObstetricsandGynaecology,UppsalaUniversityHospital,Uppsala, SE-75185,Sweden.

E-mailaddress:tansim.akhter@kbh.uu.se(T.Akhter).

https://doi.org/10.1016/j.ejogrb.2021.01.016

ContentslistsavailableatScienceDirect

European

Journal

of

Obstetrics

&

Gynecology

and

Reproductive

Biology

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Preeclampsia(PE)complicates3–5%ofallpregnancies[6].Risk of subsequentCVDis higherinwomenwithpreviousPE [7–9]. Preeclampsiaisassociatedwithhigherlevelsofdimethylarginines compared to normal pregnancy (NP) [10,11], whereas NP, especially in the beginning, is associated with lower levels of dimethylarginines comparetononpregnantwomen,tofacilitate NO’s activities like hemodynamic adaptation topregnancy and uterinerelaxation[12].Elevateddimethylarginines[13]together with exaggerated inﬂammation in PE [14] lead to endothelial dysfunction,underlyingmostofthesymptomsofPE.Studieshave shownthatL-arginine/ADMAratio,ratherthanonlyADMAlevelsis thekeydeterminantofNOSactivity[15],andisausefulindexfor interpretationofeffectsofADMA[16].

We previously showed that the imaging of CCA (common carotidartery) by2025MHzultrasound andtheuseofintima thicknessandintima/mediathicknessratio(I/M),insteadof CCA-IMT (intima-media thickness) better image vascular effects in those withprevalent CVD,diabetes mellitus, hypertension and hyperlipidemia[17–19],aswellasmoresubclinicalatherosclerosis inwomenwithPE,atdiagnosis,atone-yearpostpartum andat seven-yearfollow-up[20,21].

Association between dimethylarginines and CVD has been studiedextensivelyusingCCA-IMTwithvaryingresults[22–24]. We aimed to investigate whether dimethylarginines during pregnancy andtheirchanges frompregnancyup toabout one-yearpostpartumareassociatedtoCCAwalllayerdimensionsand cardiovascularriskfactorsinwomenwithandwithoutPE,because suchstudiesarelacking.

Methods Studypopulation

Thestudywasdesignedasalongitudinal,groupcomparative study. The material hasbeenused in ourpreviouspublication, regarding artery wall layer dimensions [20], and later also regardingassociationofpentraxin-3[25] andangiogenicfactors [26] to artery wall layer dimensions, in women with PE. Participantswererecruitedbetween2007and2010attheUppsala Universityhospitalandthemethodofrecruitmentusedhasbeen extensivelydescribedpreviously[20,25,26].Caseswerepregnant womenwithPEandtheywereincludedonlywhenadiagnosisof PE was confirmed. At that time, PE was defined as new-onset hypertension(140and/or90mmHg,observedonatleasttwo separate measurements6hapart),combinedwithproteinuria (2 on a dipstick or a 24h urine sample showing leakage of 300mgalbumin/24h),>20gestationalweek[27].Preeclampsia wasdefinedasearly-onsetPE(EOPE)ifdiagnosiswasconfirmed <34gestationalweek,otherwiseitwasaslate-onsetPE(LOPE).

Womeninthecontrolgroupwererecruitedinalongitudinal studyoftheCCAwalllayersinwomenwithNP[28].Ifpregnancy wasnormotensiveandresultedindeliveryingestationalweek37 ofanormalweightinfant,thiswasdeﬁnedasNP.Controlswere matchedtocasesfor2gestationalweeks.For bothcasesand controls, exclusion criteria were chronic hypertension, renal disease,pre-gestationalorgestationaldiabetesmellitus.

Assessmentatinclusionandpostpartum

Data onmaternal demographics were recorded at inclusion (duringpregnancy)andaboutone-yearpostpartum.Highblood pressure (BP) and obesityare two modiﬁable risk factorswith regardtothedevelopmentofCVD[29].Maternalheight,weight andBPweremonitoredduringbothassessments.Bloodpressure was measured (Umedico apparatus) according to standard procedure, with an appropriate calf-size for the arm

circumference.Accuracyofmeanarterialpressure(MAP)isbetter thansystolicBP(SBP)ordiastolicBP(DBP)inpredictingPE[30] andwascalculatedasDBP+1_/

3(SBP-DBP).Dataaboutpossible

pregnancy-relatedcomplicationsand pregnancyoutcomeswere collectedthroughreviewingthemedicalrecords.Infantsbornwith birthweights>2SDsbeloworabovethemeanbirthweightfor gestationalageweredeﬁnedassmall-orlarge-forgestationalage infantsrespectively[31].

Bioanalyticalmethod

Blood samples were taken in a heparinized tube at both assessments.Noneoftheparticipantswereinactivelabor,nordid theyhaveruptureofmembranesorsignsofinfectionatthetimeof bloodsampling.Thesampleswerecentrifugedfor10minat2000g andthentheplasmasampleswereseparatedandstoredat–70_C untillevelsofdimethylarginineswereanalysed.

The determination of plasma levels of ADMA, SDMA and L -arginine was performed withliquid chromatography– tandem mass spectrometry (LC–MS/MS) at the National Veterinary InstituteinUppsala,Sweden.Thecalibrationofallthreeanalytes was performed using the peak area ratio of analyte/internal standard,usingalinearregressionwiththeweight1/x2_._ADMA_had

a measurementintervalof 0.09–3.4

m

Manda relativestandard deviation(RSD%)inmeasuredconcentrationof(precision)5.3–7.3 %. SDMA had a measurement interval of 0.38–3.0

m

M with a precisionof5.8–9.3%.L-argininehadameasurementintervalof 4.5–150

m

Mandaprecisionof3.5–6.2%.Adetaileddescriptionof analyticalproceduresisavailableinapreviousstudy[32]andin thesupplementarymaterial.

UltrasoundimagingoftheCCA

SeparateestimatesofleftCCAintimaandmedialayerswere made with a broadband probe with 22MHz center-frequency (Collagenoson,MinhorstCompany,Meudt,Germany)(FigureS1).A detaileddescriptionofthemethodhasbeengiveninourprevious reports [17,18]. Ultrasound evaluation was not adjusted to the cardiac cycle. About 20 images were saved on a PC by one researcherMaritaLarsson(ML)andanalysedoff-linebyanother researcher Tansim Akhter (TA), the latter being blinded with regards to the identities within the study group and time of assessment.Meansof about10technicallyacceptable measure-mentswerecalculatedandusedintheanalysis.Thecoefﬁcientof variationinourlaboratorywas3.9%forintimathicknessand3.4% formediathickness[17].

Outcomes

To investigate whether dimethylarginines during pregnancy andtheirchangesfrompregnancyuptoaboutone-year postpar-tum are associated to arterial wall layer dimensions and cardiovascularriskfactorsinwomenwithandwithoutPE. Ethicalconsiderations

ThestudyprotocolwasapprovedbythelocalEthicsCommittee of the Medical Faculty of Uppsala University, Dnr 2006/259. Informedwrittenconsentwasobtainedfromeachwomanbefore theirinclusion.

Statisticalanalysis

Theresultsarepresentedasmedianwithinterquartileranges. Differences in distributions were tested by Chi-square tests. Between-groupdifferences weretested using Mann-WhitneyU

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test(adjustedforage,BMIandgestationallengthatinclusion,not forBPastheBPisacriterionfordiagnosisofPE)andwithin-group differencesusingtheWilcoxonsignedranktest.Spearmanrank correlationtestwasusedfortestofcorrelationonthecombined group(PEandNP),justifiedbysubstantialoverlappingbetween studygroupswithregardtodimethylargininelevels(Fig.1).The95 % confidence interval was calculated using percentileBoostrap confidenceintervalbasedon1000samples.Thelevelofsigni fi-cancewassetatpvalue<0.05.Statisticalanalysiswasperformed using the SPSS, version 22.0 (SPSS Inc. PASW statistics) for Windowssoftwarepackage.

Results

Asextensivelydescribedinourprevious study[20],TableS1 showsthedemographicdataofthestudypopulation.Atbaseline, 55womenwithPEand64womenwithNPwereincluded.Atthe postpartum examination, 48 women in the PE group and 58 womeninNPgroupremainedforevaluation,therebyenablingour aimtoevaluatethechangesfrompregnancytopostpartum.

Atinclusion,46/48womenhadantihypertensive medication, howevernooneneededtocontinuethetreatmentsixweeksafter delivery. As we showed in our previous publication [20], cardiovascular risk factors, i.e., BMI, SBP, DBP and MAP were signiﬁcantlyhigher inwomenwithPEthaninwomenwithNP, both during pregnancy and at about one-year postpartum (Table S2). Further, women with PE had signiﬁcantly thicker intima,thinnermediaandhigherI/MthanwomenwithNP,butno differenceinCCA-IMT(TableS2)[20].

Duringpregnancy,afteradjustmentforage,BMIandgestational length, women withPE had signiﬁcantly higher plasma ADMA (p<0.01), SDMA (p<0.0001), and lower L-arginine/ADMA

(p<0.01) and L-arginine/SDMA (p<0.001), than women with NP. In women with PE, there was a reduction of ADMA, and especiallySDMAlevelsfrompregnancytopostpartum,whereas theselevelshadincreasedinwomenwithNP.LevelsofL-arginine and L-arginine/ADMAand L-arginine/SDMA had increased from pregnancytopostpartumforbothPEandNPgroups.However,at postpartum,thelevelsofL-argininewerehigherinwomenwithNP thaninwomenwithPE(Table1).Insub-analysis,afteradjustment for gestational lengthat inclusion, there was nodifferences in dimethylarginines during pregnancy between EOPE and LOPE (datanotshown).

During pregnancy, for the combined groups, there was a positivecorrelationbetweenADMAandSDMA levelsvs. intima thickness (rs=0.29/0.33 and p<0.01/<0.001 respectively); I/M (rs=0.24and0.30respectivelyandp<0.01forboth);BMI(rs=0.19 and p<0.05 for both); SBP (rs=0.38/0.39 respectively and p<0.0001 for both); DBP (rs=0.41/ 0.38 respectively and p<0.0001 for both) and MAP (rs=0.42/0.40 respectively and p<0.0001forboth)(Table2).Consequently,L-arginine/ADMAand L-arginine/SDMA showed a negative correlation vs. intima thickness(rs=0.33/0.35 andp<0.001/<0.0001respectively); I/M (rs=0.22/0.26 and p<0.05/<0.01 respectively) (Fig. 1)

(Table 2); BMI (rs=0.23/0.20 respectively and p<0.05 for

both);SBP(rs=0.37/0.39respectivelyandp<0.0001forboth); DBP(rs=0.39andp<0.0001forboth)andMAP(rs=0.40and p<0.0001forboth)(Table2).

One-year postpartum, no signiﬁcant correlation remained betweendimethylargininesvs. arterialwall layerdimensionsor cardiovascularriskfactors(datanotshown).However,withregard tochangesindimethylargininesandarterywalllayerdimensions from pregnancy to postpartum, ADMA and SDMA levels were positively associated vs. intima thickness (rs=0.22/0.32 and

Fig.1.Correlationsbetweencommoncarotidarteryintima/mediaratiovs.plasmalevelsof(A)L-arginine/ADMAand(B)L-arginine/SDMAratiosduringpregnancyinwomen

withpreeclampsia(circles)andinwomenwithnormalpregnancies(triangles),assessedusingtheSpearmanRankCorrelationtest.rs,correlationcoefﬁcient. Table1

Plasmalevelsofdimethylargininesduringpregnancyandatpostpartuminthecombinedgroups.

Characteristics Preeclampsia NormalPregnancies

Duringpregnancy One-yearpostpartum Duringpregnancy One-yearpostpartum

(n=48) (n=48) (n=58) (n=58) ADMA(micm/L) 0.50(0.41,0.61)* 0.47(0.38,0.57)† 0.40(0.36,0.44)z 00.52(0.43,0.62) SDMA(micm/L) 0.61(0.52,0.76)x,{ 0.46(0.41,0.52)|| 0.48(0.40,0.58){ 00.53(0.47,0.68) L-Arginine(micm/L) 39(32,54)z 71(53,83)† 44(38,50)z 887(64,107) L-Arginine/ADMA 87(66,117)*,{ ₁₄₃_(119,₁₈₇₎ ₁₀₄_(93,₁₃₉₎z ₁₆₁_(127,₁₈₆₎ L-Arginine/SDMA 67(43,89)#,{ ₁₅₃_(120,₁₇₈₎ ₉₂_(73,₁₂₂₎z ₁₅₁_(123,₁₈₄₎

Medians(interquartileranges).ADMA,asymmetricdimethylarginine;micm/L,micromole/liter;SDMA,symmetricdimethylarginine. *p<0.01,†p<0.05,x,||

p<0.0001and#

p<0.001comparedtocorrespondingperiodinwomenwithnormalpregnancy,afteradjustmentforage,BMIandgestationallengthat inclusionexcept†and||

.

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p<0.05/<0.01respectively);I/M(rs=0.22/0.31andp<0.05/<0.01 respectively)andL-arginine/SDMAwerenegativelyassociatedvs intima thickness (rs= -0.21 and p<0.05) (Table 3). Similarly, changesinADMAandSDMAlevelswerepositivelyassociatedand changesinL-arginine/SDMAwasnegativelyassociatedvs.changes in SBP(rs=0.26/0.53/0.23and p<0.01/<0.0001/<0.05, respec-tively), DBP (rs=0.26/0.46/0.21 and p<0.01/<0.0001/<0.05, respectively) and MAP (rs=0.31/0.53/0.25 and p<0.01/ <0.0001/<0.05,respectively)(Table3).

For analysis of CCA-IMT, again we found no signiﬁcant correlations toanalyseddimethylarginines,neitherduring preg-nancy(Table2)orone-yearpostpartum(datanotshown)norin theirchangesfrompregnancytopostpartum(Table3).

Discussion

To ourknowledge this is the first report showing dimethy-largininesassociatetosignsofadverseeffectsonCCAwalllayer dimensions in women during pregnancy, as well as in their changesuptoone-yearpostpartum.Further,significantandlogical correlations between carotidintima and I/M,BMI and BPwith regardtoanalyseddimethylarginineswerefound.Incontrast,for conventional CCA-IMT, none of these tests were found to be significant.Further,correlationsforintimathicknesswereoften strongerthanforI/M,whichisexpectedconsideringtheshorttime periodduringpregnancyandthatchangesinintimathicknessis thefirstmorphologicsignintheatherosclerosisprocess[33,34]. Testofcorrelationinthecombinedstudygroupsaimedtofocuson

vasculareffectsofthedynamicinplasmadimethylargininesperse. Correlationsweresigniﬁcantdespitearterywalllayerdimensions are temporarily adversely affected during NP [28], whereas dimethylargininesarelower(improved)duringNP,comparedto non-pregnancy.

WedidnotadjustourresultsforBPbasedonthefactthatBPis themaincriterionfordeﬁnitionofPE.

We alsoconﬁrmed that, during pregnancy, plasma levelsof ADMA and SDMA were higher whereas L-arginine, L-arginine/ ADMA and L-arginine/SDMA were lower in women with PE, compared to women with NP. In PE, ADMA and SDMA levels decreasedfrompregnancytopostpartum,whereasinNPthelevels increased.

LowerlevelsofADMAinNP,comparedtopostpartumlevels, support the ﬁndings of Holden et al. [12] and are logical in facilitating the cardiovascular and uterine adaptation during pregnancythroughdecreasedinhibitoryeffectonNOS[12].Two possibleexplanationsforthelowerlevelsofADMAinNPcouldbe; increaseincirculatingplasmavolumewithphysiologicaldecrease inADMAlevelsandincreaseddegradationofADMAintherenal tubules [35], whereas in PE, when blood vessels become less compliant,theblood ﬂow becomesturbulent and oscillatory;a stimulus for release of superoxide, which in turn creates an environment more prone to develop atherogenic lesions [36]. Further, early in PE, an ischemic placenta,caused by impaired vasculogenesisleadstooxidativestressthatcouldberesponsible forelevatedADMAlevelsthroughthereduced dimethylarginine-dimethylaminohydrolase activity that is known to be very

Table2

Associationsofdimethylargininestocommoncarotidarterywalllayerdimensionsandcardiovascularriskfactorsduringpregnancyinthecombinedgroups.

ADMArs(95%CI) SDMArs(95%CI) L-argininers(95%CI) L-Arginine/ADMArs(95%CI) L-Arginine/SDMArs(95%CI)

CCAwalllayers

Intimathickness 0.29(0.12,0.46)* 0.33(0.17,0.48)† 0.20(0.37,0.03)z _0.33_(0.49,_0.17)† _0.35_(0.49,_0.19)x

Mediathickness 0.05(0.23,0.13) 0.09(0.26,0.09) 0.02(0.21,0.17) 0.01(0.19,0.19) 0.04(0.16,0.22)

Intima/mediaratio 0.24(0.06,0.41)* 0.30(0.13,0.44)* 0.12(-0.30,0.06) 0.22(0.39,0.04)z _0.26_(0.42,_0.07)_*

Intima-mediathickness 0.04(0.13,0.22) 0.02(0.16,0.20) 0.09(0.28,0.10) 0.12(0.31,0.08) 0.09(0.29,0.11)

Cardiovascularriskfactors Bodymassindex,kg/m2

0.19(0.00,0.36)z 0.19(0.01,0.35)z 0.16(0.32,0.03) 0.23(0.40,0.04)z _0.20_(0.38,_0.02)z

SystolicBP,mmHg 0.38(0.20,0.53)x 0.39(0.24,0.53)x 0.18(0.35,0.01) 0.37(-0.52,-0.19)x 0.39(-0.54,-0.23)x

DiastolicBP,mmHg 0.41(0.25,0.53)x 0.38(0.22,0.52)x 0.19(0.36,0.01)z _0.39_(0.55,_0.22)x _0.39_(0.54,_0.23)x

MAP,mmHg 0.42(0.26,0.54)x 0.40(0.23,0.54)x 0.19(0.36,0.01)z _0.40_(0.55,_0.22)x _0.40_(0.54,_0.24)x

Spearmanrankcorrelationtest.rs,correlationcoefﬁcient(95%CI).ADMA,asymmetricdimethylarginine;SDMA,symmetricdimethylarginine;CCA,commoncarotidartery;

BP,bloodpressureandMAP,meanarterialpressure. *p<0.01;†p<0.001;zp<0.05andxp<0.0001.

DataonCCAwalllayersreusedwithpermissionfromtheAmericanHeartAssociation[20].

Table3

Associationsofchanges(frompregnancytoaboutone-yearpostpartum)indimethylargininestochangesinarterywalllayersandcardiovascularriskfactorsinthecombined groups.

ADMArs(95%CI) SDMArs(95%CI) L-argininers(95%CI)) L-Arginine/ADMArs(95%CI)) L-Arginine/SDMArs(95%CI))

CCAwalllayers

Intimathickness 0.22(0.12,0.41)* 0.32(0.14,0.50)† 0.04(-0.16,0.24) 0.19(0.39,0.01) 0.21(0.41,0.01)*

Mediathickness 0.06(0.27,0.15) 0.08(0.27,0.09) 0.10(0.30,0.11) 0.07(0.25,0.13) 0.07(-0.25,0.12)

Intima/mediaratio 0.22(0.01,0.40)* 0.31(0.13,0.49)† 0.11(0.09,0.32) 0.08(0.30,0.12) 0.08(0.29,0.12)

Intima-mediathickness 0.02(0.18,0.24) 0.00(0.19,0.18) 0.05(0.24,0.16) 0.09(0.28,0.10) 0.09(0.27,0.09)

Cardiovascularriskfactors

Bodymassindex 0.09(0.11,0.27) 0.20(0.00,0.38)* 0.15(0.05,0.34) 0.03(0.18,0.24) 0.01(0.22,0.18)

Systolicbloodpressure 0.26(0.08,0.43)† 0.53(0.37,0.64)z 0.14(0.03,0.33) 0.06(0.26,0.15) 0.23(0.42,0.02)*

Diastolicbloodpressure 0.31(0.12,0.48)† 0.46(0.28,0.61)z 0.09(0.09,0.27) 0.19(0.38,0.02) 0.21(0.38,0.03)*

Meanarterialpressure 0.31(0.13,0.47)† 0.53(0.39,0.64)z 0.12(0.07,0.30) 0.16(0.35,0.05) 0.25(0.41,0.07)*

Spearmanrankcorrelationtest.rs,correlationcoefﬁcient(95%CI).ADMA,asymmetricdimethylarginine;SDMA,symmetricdimethylarginineandCCA,commoncarotid

artery.

*p<0.05;†p<0.01andzp<0.0001.

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sensitive to oxidative stress [13]. Later in PE, impaired renal function onthebasisof endothelialdamageleadstodecreased renalexcretionand/ordegradation,whichcouldbeanadditional mechanismtotheelevatedADMAlevels[37].

HighlysignificantandlogicalcorrelationsofADMAandSDMA andofL-arginine/ADMAandL-arginine/SDMAvs.arterywalllayer dimensions,aswellasintheirchanges,stronglysupportvascular effect of dimethylarginines in women with PE and are in accordance with theknown increasedrisk of later CVD events in these women [8,38] and support and extend our previous findings of adverse vascular effects of PE on artery wall layer dimensions [20,39]. At postpartum, L-arginine/ADMA and L -arginine/SDMAincreasedsignificantly,bothinPEandNP,mostly due toanincreaseinL-arginine, inaccordancewitha reportby Pettersson et al. [40]. Lack of significant correlations between dimethylargininesandarterywalllayerdimensionsatpostpartum might be explained by less volatility in the dimethylarginines system, being calmed down in the non-pregnant state at postpartumandthatdeviationsindimethylargininesmorereflect currentmoreacutesituations/processes.TheADMA-systemreacts quiterapidly;arecentstudybyHenrohnetal.showedthatsingle dose phosphodiesterase, PDE5-inhibitor rapidly changed the pattern of dimethylarginines levelsin patientswithpulmonary hypertension[41].

The strength of ourstudy is that we had data on dimethy-largininesandCCAwalldimensionsbothduringpregnancyandup toone-yearpostpartuminthesameindividualswithaverylow dropoutrate,whichallowedanalysisofpostpartumchanges.

One limitation is the relatively small sample size with the associated potential risk of type 2 errors;a problem for non-signiﬁcantﬁndingsonly.

Conclusions

Our results indicatethat plasma levels of dimethylarginines correlated signiﬁcantlytoCCA intimathicknessand I/Mandto cardiovascularrisk factorsbothduring pregnancy,as wellas in theirchangesuptoaboutone-yearpostpartum. Correlationsin this study do not prove causality but the results suggest that dimethylarginines might be one mechanistic link between vasculareffectsinPEandlaterriskofCVD.

Financialsupport

ALFfundingfromUppsalaUniversityHospital,ResearchCouncil ofUppsalaCountyCouncilandtheSelandersFoundation. Authorscontributions

TA and TN conceived the study. ML performed ultrasound examinations.UlfBondessonandMikaelHedelandwereresponsible for biochemical analyses. TA and TN analyzed and interpreted the data. TAdraftedthemanuscriptandTN,GW,ML,UB,andMHrevisedit. DeclarationofCompetingInterest

None,exceptthatTordNaessen(TN)isholderoftheUSPatent #8556817,‘non-invasivemethodsfordeterminingthe cardiovas-cularstatusofanindividual_’usingtheprincipleofintimathickness andI/MinsteadofconventionalCCA-IMT.

AppendixA.Supplementarydata

Supplementarymaterialrelatedtothisarticlecanbefound,inthe onlineversion,atdoi:https://doi.org/10.1016/j.ejogrb.2021.01.016.

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