Full
length
article
Placental
morphology,
apoptosis,
angiogenesis
and
epithelial
mechanisms
in
early-onset
preeclampsia
Antonio
Travaglino
a,
Antonio
Raffone
b,*
,
Gabriele
Saccone
b,
Sonia
Migliorini
b,
Giuseppe
Maria
Maruotti
b,
Gennaro
Esposito
b,
Antonio
Mollo
b,
Pasquale
Martinelli
b,
Fulvio
Zullo
b,
Maria
D'Armiento
ca
AnatomicPathologyUnit,DepartmentofAdvancedBiomedicalSciences,SchoolofMedicine,UniversityofNaplesFedericoII,Naples,Italy
b
DepartmentofNeuroscience,ReproductiveSciencesandDentistry,SchoolofMedicine,UniversityofNaplesFedericoII,Naples,Italy
c
DepartmentofPublicHealth,SchoolofMedicine,UniversityofNaplesFedericoII,Naples,Italy
ARTICLE INFO
Articlehistory:
Received23September2018
Receivedinrevisedform4December2018 Accepted28December2018 Keywords: Placenta Earlypreeclampsia Villoushypoplasia Immunohistochemistry ABSTRACT
Objectives:Early-onsetpreeclampsiaisaformofpreeclampsiarequiringdeliverybefore34weeksof
gestation. The etiology is unknown, but placental dysfunction appears crucial. We evaluated the
immunohistochemicalexpressionoftheantiapoptoticproteinBcl-2,theangiogeneticfactorsVEGFand
PlGF,andtheepithelialfactorsHGF,c-MetandSTAT3inplacentalsamplesofpregnanciescomplicatedby
early-onsetpreeclampsia.
Materialsandmethods:Placentalsectionswereobtainedfrom41womenwithearly-onsetpreeclampsia
(cases)andfrom31uncomplicatedpregnancies(controls).Astandardhaematoxylinandeosinstainwas
usedtoassesshistologicalstructure.ImmunohistochemicalexpressionofBcl-2,VEGF,PlGF,HGF,c-Met
andSTAT3wasanalyzed.
Results:Meangestationalagewas32weeksincasesand39weeksincontrols.Microscopically,sections
fromwomenwithpreeclampsiashowedadisorderofvillousdevelopmentasadistalvilloushypoplasia
with placental undergrowth. The immunoistochemical expression of Bcl-2 (p<0.0001), VEGF
(p=0.0323), PlGF (p=0.002), HGF (p<0.0001), c-Met (p<0.0001) and STAT3 (p=0.0004) were
significantlylowerinplacentasofcomplicatedpregnanciescomparedtouncomplicatedones.
Conclusions:Early-onsetpreeclampsiaisassociatedwithadisorderofvillousdevelopment.Apoptotic,
angiogenetic and epithelial mechanisms are simultaneously impaired and contribute to placental
dysfunctions.
©2019ElsevierB.V.Allrightsreserved.
Introduction
Preeclampsia(PE)complicatesabout2–8%ofpregnancies,and isamajorcauseofmaternalandperinatalmorbidityandmortality [1]. PE impairs functioning of the kidneys, liver, and central nervoussystem[1].Earlypreeclampsiaisdefinedbythepresence of a severe form of PE requiring delivery before 34 weeks of gestation[2]
AlthoughtheetiologyofPEremainspoorlyunderstood[1–30],it ishypothesizedthatplacentaldysfunctionmayhaveacrucialrole [31,32].AcommonphenomenonobservedinPEistheabnormal
development and function of the placenta associated with an abnormalinvasionandremodelingofmaternaluterinearteriesby extravilloustrophoblasts[4].Apoptotic,angiogeneticandepithelial mechanismsseemtobeinvolvedinplacentalinsufficiency.
ExaggeratedplacentalapoptosisisacommonfeatureinPE[5]. B-cell lymphoma/leukemia(Bcl-2) is specifically considered as an important antiapoptoticproteinand hasbeenshownto prevent apoptosisbyblockingcytochromeCreleasefrommitochondria[6]. Bcl-2maybedownregulatedinplacentasfrompatientswithPE[5]. VascularEndothelialGrowthFactor(VEGF)andthePlacental GrowthFactor(PlGF) aremajorfactorsregulating theplacental angiogenesisforanadequateplacentaldevelopmentandfunction. Defective actionof theseangiogeneticfactorsappearstoplaya majorroleinPE[3].
Epithelialgrowth factorsarealsoinvolvedinproliferationof trophoblasticcells.Amongthese,HepatocyteGrowthFactor(HGF), its receptorc-Metand the transcriptional factorSTAT3 play an
*Correspondingauthorat:DepartmentofNeuroscience,ReproductiveSciences andDentistry,SchoolofMedicine,UniversityofNaplesFedericoII,ViaSergio Pansini,5,Naples,80131,Italy.
E-mailaddress:[email protected](A.Raffone).
https://doi.org/10.1016/j.ejogrb.2018.12.039
0301-2115/©2019ElsevierB.V.Allrightsreserved.
ContentslistsavailableatScienceDirect
European
Journal
of
Obstetrics
&
Gynecology
and
Reproductive
Biology
important role in regulation of normal fetal and placental development[7,8]. HGFisacytokinethatisabletogenerate,in cMETexpressingcells,thebranchingmorphogenesisthatinvolves cellular changes in cell shape and cell polarization, cellular migrationand cellularproliferation,creating thetridimensional branching extension [9]. A defective expression of HGF/c-Met/ STAT3 pathway appears characteristic of organs and placentas frommalformedfetuses[7,8].
The placental expression of antiapoptotic, angionenetic and epithelial growth factors normally increases during pregnancy until about 30 weeks with placental development, and then graduallydecreaseswith placental aging [33,34]. By definition, early-onset PE requires delivery before 34 weeks of gestation, when the activityof these factor should benear its peak. We hypothesizedthatsuchprocessmightbeimpairedinearly-onset PE,andthattheexpressionofthesefactormightbelowerthanin uncomplicatedpregnancies.
Theaimofourstudyistoevaluatetheimmunohistochemical expressionofBcl-2,PlGF,VEGFHGF,c-MetandSTAT3inplacental samplesfromwomenaffectedbyearly-onsetPEcomparedwith uncomplicatedpregnancies.
Materialsandmethods Studyprotocol
Thestudyprotocolincludingmethodsforcollection,analysis and interpretation of data was defined apriori. The study was designedasaretrospectivecase-controlstudyandwasreported followingtheSTROBEguidelines[10].
Clinicaldataofpatientswereobtainedbyreviewingmedical records of the Department of Neuroscience, Reproductive SciencesandDentistryoftheUniversityFedericoII,Naples,Italy. Data about gross and histologic examinations of placental specimens were retrieved from electronic databases of the Anatomic Pathology Unit of the Department of Advanced BiomedicalSciences,University FedericoII,Naples, Italy. Paraf-fin-embeddedspecimenswereretrievedfromthearchivesofthe same unit to perform ad hoc histomorphologic reviews and immunohistochemicalanalyses.
Cases
DiagnosisandmanagementofPEwasbasedonACOGguidelines [1].PEwasdefinedasabloodpressureelevation(140/90ontwo occasionsfour hoursapartor 160/110once), after 20 weeksof gestation,withproteinuria(300mgon24hproteinor>0.3protein/ creatinineratio)oranyofthefollowingifproteinurianotpresents: platelets <100,000; creatinine >1.1 (or doubling of creatinine in absenceofotherrenaldisease);doublingofASTorALT.PEwithsevere featureswasdefinedaspreeclampsiawithanyofthefollowing:blood pressure160/110fourhoursapartonbedrest(unlesson antihyper-tensive); platelets<100,000;doubling ofASTor ALT;creatinine>1.1(or doublingofcreatinineinabsenceofotherrenaldisease);pulmonary edema; new cerebral or visual disturbances. Early-onset PE was definedasPErequiringdeliverybefore34weeksofgestation.
Forthisstudyweincludedwomenwithsingletongestations andwithearly-onsetPEwithoutfetalmalformations.Weincluded allconsecutivecasesfromMarch2009toApril2011
We selected as cases only women affected by early-onset PE,sinceitisconsideredasadistinctdiseasefromlate-onsetPE[1], andischaracterizedbyhigherriskoffetalandperinatalmorbidity/ mortality[2].TounderstandwhetherHGF/c-Met/STAT3pathway deficiencycharacterizesPEindependently fromfetal malforma-tions, we included in our study only placentas from fetuses withoutmajorcongenitalmalformations.
Controls
Controlswerelow-riskpregnantwomenwithuncomplicated singleton gestations. Intrauterine growth restriction (IUGR), chronic hypertension, diabetes, renal diseases were excluded. Controlswererandomlyselectedinthesameperiodasthecases. Forbothcasesandcontrols,gestationalagehadbeenassessed bythelastmenstrualperiodandconfirmedbyultrasound. Placentalspecimens
Placentashadbeencollectedafteracaesareansectionandfixed for24hin4%phosphate-bufferedformaldehyde(Ph7.2).Weight and diameterhad beenmeasured foreach specimen;umbilical cordandmembraneswereremovedbeforeweightmeasurement. Sampling protocol included seven full-thickness section of the chorionicplate(fourcentral,approximatelyequallyspaced, and threeperipheral),twosectionsofthemembranesandtwosections ofthecord.Afterthat,thetissueshadbeenembeddedinparaffin (meltingpoint52C);4
m
mparaffinsectionshadbeenmountedon glassslidescoveredwith3-amino-propyl–ethoxy3silane(Sigma,Table1
Characteristicsofstudypopulation.
Casesn=41 Controlsn=31 Gravidity
Median(25-75%;range) 1(1–2;1–7) 2(1–3;1–4) Parity
Median(25-75%;range) 0(0–0;0–2) 1(0–2;0–3) Gestationalage(weeks)
AverageSD 322,4 391,2 Maternalage(years)
AverageSD(range) 3164,4(23–41) 3351,2(23–41) Race% Whiten(%) 41(100) 31(100) Ethnicity Caucasiann(%) 41(100) 31(100) Prenatalmedications Ironn(%) 20(50) 15(484) Vitamineand/orfolicacidn(%) 41(100) 31(100) Antihypertensivedrugsn(%) 41(100) 0(0) Smoking(beforepregnancy)
Cigarettesn(%) 5(122) 0(0) Previousprenataladmission(s)
Yesn(%) 0(0) 0(0)
Antibioticsinlabor
Nonen(%) 41(100) 31(100) Betastrepstatus
Positiven(%) 12(293) 11(355) Antenatalsteroids: Yesn(%) 41(100) 0(0) GAmeanSD 312 0(0) Magnesiumsulfate Yesn(%) 0(0) 0(0) Anesthesia Epiduraln(%) 41(100) 31(100) Cervicalripeningagent
Nonen(%) 41(100) 31(100) Labor
Yesn(%) 0(0) 0(0)
Deliverymode
C-sectionn(%) 41(100) 31(100) MaternalOxygengivenatdelivery?
Yesn(%) 0(0) 0(0)
Birthweight(grams)
AverageSD 1541800 2900300 Placentalweight(grams)
AverageSD 322103 55627 Baby’ssex
Femalen(%) 25(61) 18(581) Deliverytoprocessing(mins)
Deisenhofen,Germany)andastandard52haematoxylinandeosin stainhadbeenusedtoassesshistologicalstructure.
Immunohistochemistry
Immunohistochemistrywascarriedwithpolyclonalrabbit anti-bodiesagainst:HGFα(H-145,sc-7949,200
m
g/ml,1:50,SantaCruz Biotechnology,SantaCruzCA),c-Met(B-2,sc-8057,200m
g/ml,anti h-met,1:50,SantaCruzBiotechnology),STAT3(h-190,sc-7179,200m
g/ ml,1:50,SantaCruzBiotechnology),VEGF(A-20,sc-152,100m
g/ml, 1:200,SantaCruzBiotechnology,recommendedfor189,165and121 aminoacidsplicevariantsofVEGF-A),PlGF(C-20,sc-1880,200m
g/ml, 1:50,SantaCruzBiotechnology),andmousemonoclonalantibody againstBcl-2(124,M0887,200m
g/ml,1:100,DAKO).Briefly, sectionsweredeparaffinisedwithxylene,rehydrated throughagradedseriesofethanolsolutionstodistilledwater,PBS (phosphatebufferedsaline)wasusedforallsubsequentwashesand forantiserumdilution.Tissuesectionsweretreatedsequentiallyin 0.3%hydrogenperoxideabsolutemethanolfor30mintoquench theendogenousperoxidaseactivity.Slideswerethenincubatedat 4Covernight.AfterthreewashesinPBStoremovetheexcessof antiserum, the slides were incubated with goat anti-rabbit biotinylatedantibodies(Vectorlaboratories, BurlingameCA,U.S. A.)at1:200dilutioninPBS3%for1h,allslideswerethenprocessed by the ABC method (Vector laboratories) for 30min at room temperature. Diaminobenzidine (Vector Laboratories) activated with0.05%hydrogenperoxidewasusedasfinalchromogenand Mayer’s haematoxylinwas usedas thenuclearcounterstaining. Negativecontrolsforeachtissuesectionswerepreparedbyleaving outtheprimary antiserumand replacingit withnormal rabbit serum. Positive controls were represented by vascular tumor (angioma),breastcarcinoma,coloncarcinoma.Allsampleswere processed under the same conditions. Immunocytochemical evaluationwasperformedbylocalization(epithelial,endothelial mesenchymal)andbyquantificationofreactivity.
Analysisandinterpretationofdata
Themainoutcomeconsideredwastheimmunohistochemical expression of Bcl-2, PlGF, VEGF HGF, c-Met and STAT3 in the placentalspecimens.
The markers expression was dichotomized into negative or positive, based on the number of reactive cells<or >10% respectively,fromobservationof10fieldsusing40xmagnification. Intensityofimmunohistochemicalstainingwasscoredasfollows: 0=completeabsenceofstaining;1=weakintensityofstaining;2= moderateintensityofstaining;3=strongintensityofstaining.
Histological and immunocytochemical evaluation were per-formedindependentlybyanexpertperinatalpathologist(MDA) andasecondpathologist(AT),whowereblindedtoclinicaldata. Disagreements were resolved by discussion at a two-headed microscope.
Univariate comparisons between cases and controls were performedbyusingFisher'sexacttestfortwo-tailedPvaluewith α=0.05significancelevel.
StatisticanalysiswereperformedusingSPSS17.0package(SPSS Inc.,Chicago,IL,USA).
Results
Characteristicsofwomen
Forty-onewomenwereincludedinthecasesgroupand31in thecontrolgroup.
In cases andcontrols, themeanmaternal agewas 31.64.4 years (range: 23–41) and 33.51.2 years (range: 23–41), the
gestationalagewas322.4weeksand391.2weeks,themedian graviditywas1(range:1–7)and2(range:1–4),themedianparity was 0(range:0–2)and 1(range:0–3),respectively. Allwomen werewhiteandCaucasian.Amongcasesandcontrols,only5cases (12.2%)weresmokerspriortopregnancy.Allwomendeliveredby cesareansectionandnonewbornspresentedmalformations.
Characteristicsarereportedindetail inTable 1,accordingto Nelsonetal.[12].
Characteristicsofplacentas
In cases and controls, placental weight was 322103 and 55627g and placental diameter was 122 and 182cm, respectively.
Microscopically, all cases showed a disorder of villous development as a distal villous hypoplasia with placental undergrowth(Fig.1).The distal villi weredecreased especially in the center of the placental lobule. Residual distal villi were sparse, thin, non-branching, poorly vascularized, with focal increaseinthenumberofsyncytialknots(Tenney-Parkerchange). The tertiarystem villiwere prominent atthe periphery of the lobule, they showed increased stromal collagen, muscular hypertrophyofarterioles,intervillousfibrinandvillous agglutina-tion.Therewasfocalhypertrophicdecidualvasculopathy.
On the other hand, no morphologic abnormalities were observedincontrols’placentas.
Immunohistochemicalfindings
Wherepositive, theexpression ofVEGF, PlGFand Bcl-2 was localizedincytotrophoblasticcells.NegativeexpressionofVEGF, PlGF and Bcl-2 was observed in 14 (34.1%),19 (46.3%) and 33 (80.5%) cases respectively, and in 3 (9.7%), 3 (9.7%) and 0 (0%) controlsrespectively.Negativeexpressionwassignificantlymore
Fig. 1.Alteration of morphology of chorionic villi in women with early preeclampsia:acceleratedmaturation(A)andimmaturity(B).
Fig.2.Immunohistochemicalexpressionof:Bcl-2incases(A,100X)andcontrols(B,40X);VEGFincases(C,40X)andcontrols(D,40X);PlGFincases(E,40X)andcontrols(F, 40X);HGFincases(G,100X)andcontrols(H,200X);c-Metincases(I,200X)andcontrols(L,200X);STAT3incases(M,40X)andcontrols(O,100X).
commonincasesthanincontrolsforallmarkers(VEGFp=0.0323; PlGFp=0.002;Bcl-2p<0.0001)
Wherepositive,theexpressionofHGF,c-MetandSTAT3was localized in the cytoplasm of epithelial cells, fibroblast and myofibroblastcells.NegativeexpressionofHGF,c-MetandSTAT3 was observed in 27 (65.8%), 26 (63.4%) and 29 (70.7%) cases
respectively, and in 1 (3.2%), 1 (3.2%) and 8 (25.8%) controls respectively.Negativeexpressionwassignificantlymorecommon incasesthanincontrolsforallepithelialmarkers(HGFp<0.0001; c-Metp<0.0001;STAT3p=0.0004)(Fig.2).
Immunohistochemicalfindingsaresummarized inTables 2and 3. As expected, significant direct correlation was observed amongst epithelial factors (HGF, c-Met and STAT3); Bcl-2 and PlGFdirectlycorrelatedwithepithelialfactorsaswell.Significant inversecorrelationwasfoundbetweenthetwoangiogenicfactors VEGFandPlGF(Table4).
Discussion
Our study showed that a concomitant alteration in the expression of apoptotic, angiogenetic and epithelial factors is involvedinplacentaldysfunctionsunderlyingPE,independently fromfetalmalformationsandwithspecificregardtoearly-onset PE.
Table2
ImmunohistochemicalexpressionofHGF,c-Met,Stat3,Bcl-2,VEGF,PlGFincases andcontrols.
Marker Negativeexpression p-value Casesn(%) Controlsn(%) Bcl-2 33(805) 0(0) <0.0001 VEGF 14(341) 3(9.7) 0.0323 PlGF 19(463) 3(9.7) 0.002 HGF 27(65.8) 1(3.2) <0.0001 c-Met 26(63.4) 1(3.2) <0.0001 Stat3 29(707) 8(25.8) 0.0004 Table3
IntensityofimmunohistochemicalexpressionofHGF,c-Met,Stat3,Bcl-2,VEGF,PlGFineachcaseandcontrol.
CONTROLS CASES
N Bcl-2 VEGF PlGF HGF
c-Met STAT3 N Bcl-2 VEGF PlGF HGF Metc- STAT3
1 2 3 2 3 2 3 1 2 3 1 0 1 1 2 3 2 3 3 2 2 2 2 2 3 2 2 2 3 3 2 3 2 3 1 3 2 2 2 3 2 3 4 3 3 3 3 2 1 4 0 2 2 3 2 2 5 3 3 3 3 2 1 5 0 2 1 0 1 0 6 2 2 2 3 2 2 6 1 1 3 3 2 2 7 2 2 3 2 3 2 7 2 1 2 3 2 3 8 3 2 3 3 3 3 8 0 1 1 0 0 0 9 3 3 3 3 3 2 9 1 2 0 0 1 1 10 2 2 2 3 2 2 10 0 1 2 1 1 1 11 2 2 3 3 2 3 11 1 2 1 0 1 1 12 2 2 3 3 2 2 12 0 3 1 0 1 1 13 3 2 3 3 2 2 13 1 1 3 3 2 3 14 3 3 2 3 3 2 14 2 1 2 1 2 2 15 2 2 2 2 2 1 15 0 3 1 0 1 1 16 2 3 2 2 2 2 16 1 1 2 2 1 1 17 3 3 2 3 2 3 17 1 2 1 2 1 1 18 3 1 3 3 2 1 18 1 1 2 1 1 1 19 2 1 3 2 2 2 19 1 1 2 1 1 1 20 2 2 3 2 2 2 20 1 3 1 0 1 1 21 2 1 3 2 2 1 21 2 2 3 2 2 2 22 2 3 0 3 3 3 22 2 2 2 2 2 1 23 3 3 0 2 2 2 23 0 1 2 2 2 2 24 3 3 1 3 2 2 24 0 2 1 1 1 1 25 2 1 3 3 2 3 25 0 1 2 2 1 1 26 3 2 2 2 3 2 26 0 2 2 1 1 1 27 3 2 2 2 2 2 27 1 2 2 1 1 1 28 2 1 3 3 3 2 28 1 2 2 2 2 2 29 3 2 3 2 3 1 29 0 2 2 1 1 2 30 2 2 3 3 3 2 30 1 3 1 1 2 1 31 2 3 3 1 1 1 31 0 3 0 0 0 0 32 1 2 2 1 2 1 33 0 2 0 0 0 0 34 1 1 2 2 2 1 35 1 3 1 1 1 1 36 0 3 1 0 1 1 37 2 2 1 1 2 2 38 0 3 0 0 1 1 39 1 1 2 1 1 1 40 0 1 1 1 1 1 41 1 2 1 1 1 1
PE is often accompaniedby hypoxia and reperfusionof the placenta,andthisconditionmayinduceapoptosisintrophoblastic cells.Thishypoxia-inducedapoptosisisaccompaniedbydecreased expressionofBcl-2.Increasedapoptosistogetherwithdecreased invasionandmigrationabilityoftrophoblastcellsintheplacenta havebeenproposedasamajorcausesofPE[5].
Endothelial dysfunction, caused by suppression of VEGF signaling,alsoseemstobea majorfactorinvolvedin PE.VEGF andPlGFareangiogeneticfactorwhichpromote pseudovasculo-genesis, i.e. the transformation on cytotrophoblast from an epithelia intoan endothelialphenotype. SecretionofVEGF and PlGFisnormallyinducedintrophoblastcells.InPE,increasedlevel of the soluble fms-like tyrosine kinase 1 (sFlt-1) led to a suppression of VEGF and PlGF signalling, which may partially explain the vascular remodeling disorderdescribed in patients with preeclampsia. Circulating levels of PlGF have been found decreased inwomenwithseverepreeclampsia comparingwith normotensivepregnant[3].
Regardingepithelialfactors,thecascadeofHGF/c-Met/STAT3 playsakeyroleinproliferationandmorphogenesisofmanycells and tissues,including trophoblast. HGF is a pleiotropic mesen-chyme-derivedcytokineproducedbyfibroblastsandingeneralby mesenchymal cells, promotinghepatocyte proliferation in vitro [13]. HGF,binding c-Met,leads todimerization, autophosphor-ylationand transientassociationofthereceptor with cytoplas-matic STAT3 protein. This association induces STAT3 phosphorylation followed by translation to the nucleus [14]. STAT3inducesbranchingformation,cellmigration,cell prolifera-tionandmorphogenesisofthetrophoblast[15,16].Also,ithasbeen demonstrated that insufficient HGF production leadsto kidney fibrosis [17]. Preeclampsia is associated with characteristic glomerular lesions, known as glomerular endotheliosis, and it appearsthatproteinuriainPEistheresultofdirectinjurytorenal podocytes[18].Thus,itispresumablethatHGF/cMetmayplaya roleintherenaldysfunctionofpatientswithPE.
Inourseries,allthestudiedfactorsshowedasignificantlylower expressionincomplicatedpregnanciesthanuncomplicatedones. Thisresultappearsevenmoreinterestingifweconsiderthatthe expressionofthesemoleculesgraduallydecreasesafterabout30 weekswithplacentalaging,andthusitshouldhavebeenhigherin cases(meangestationalage=32 weeks)thanincontrols(mean gestational age=39 weeks). Also the placental morphology showed important differences between the two groups: cases showed a disorder of villous development as a distal villous hypoplasia with placental undergrowth, while the controls showednoabnormalities.Placentawithdistalvilloushypoplasia isunabletoabsorboxygen.Thispathologicaspectcouldresultin placentaldysfunctionandabnormalfeto-maternalflows[19].
Oursamplemaybethelargestintheliteratureassessingc-Met andSTAT3,andthesecondlargestassessingHGF[20].Moreover,
this is the largest study evaluating c-Met, STAT3 and HGF specifically in early-onsetPE (<34weeks),which is considered asaconditiondistinctfromlate-onsetPE[2].
To ourknowledge, ourstudy is thefirst to assess all these apoptotic,vascularand epithelialfactorstogether,showingthat thethreemechanismsaresimultaneouslyinvolvedintheplacental dysfunction underlying PE. Such a finding is consistent with scientific evidence on the interactions between these factors. Indeed,VEGFcaninhibitapoptosisbyinducingexpressionofBcl-2 [21],andSTAT3proteinisalsoimplicatedintheregulationofVGFR expression[22].
Anotherstrengthofourstudywasthecollectionoftheanalyzed tissues. In fact, the investigated cases included no malformed fetuses’placentasinpregnanciescomplicatedbyearly-onsetPE. This allowed to eliminate a possible confounding factor, as deficiency of HGF/c-Met/STAT3 pathway has been shown in organsandplacentasfrommalformedfetuses[7,8].
Ontheotherhand,themajorlimitationofourstudymaybethe lackofmatchingbetweencasesandcontrolswithregardtosome characteristics,e.g.gestationalage.However,asdiscussedabove, thedifferenceinthegestationalageshouldnotaffectourresults, butratheritmightevenstrengthenthem.
Further studies are necessary to clarify etiopathogenetic mechanismsunderlyingearly-onsetPE,andtoeventuallyidentify noveldiagnosticandtherapeutictargets.
Conclusion
Early-onset PE is associated with a disorder of villous development, as a distal villous hypoplasia with placental undergrowth.Apoptotic,angiogeneticandepithelialmechanisms aresimultaneouslyinvolvedinplacentaldysfunctionsunderlying early-onsetPE,astheexpressionofBcl-2,PlGF,VEGFHGF,c-Met and STAT3 appeared significantly decreased in placentas from womenwithpreeclampsia.Suchassociationisindependentfrom fetuses’malformations.
Disclosureofinterest
Theauthorsreportnoconflictofinterest. Funding
Nofinancialsupportwasreceivedforthisstudy. References
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Table4
P-valuesofthestatisticalassociationamongstthemarkersassessed.
Bcl-2 VEGF PlGF HGF c-Met STAT3
Bcl-2 - 0.6925 0.2488 0.0966 0.0018* 0.0042* VEGF 0.6925 - 0.0038** 0.1703 0.4816 0.7186 PlGF 0.2488 0.0038** - 0.0003* 0.0028* 0.002* HGF 0.0966 0.1703 0.0003* - 0.0001* 0.0008* c-Met 0.0018* 0.4816 0.0028* 0.0001* - <0.00001* STAT3 0.0042* 0.7186 0.002* 0.0008* <0.00001*
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