braz j infect dis 2 0 1 6;20(2):115–118
w w w . e l s e v i e r . c o m / l o c a t e / b j i d
The
Brazilian
Journal
of
INFECTIOUS
DISEASES
Original
article
Toxoplasmic
encephalitis:
role
of
Human
Leucocyte
Antigens/alleles
associated
with
rapid
progression
to
Acquired
Immunodeficiency
Syndrome
Maria
de
Lourdes
Rodrigues
a,
Neifi
Hassam
Deghaide
b,
José
Fernando
Figueiredo
b,
Marcelo
Bezerra
de
Menezes
a,
Ana
Lúcia
Demarco
a,
Eduardo
Donadi
b,
Ana
Paula
Fernandes
c,∗aDepartmentofOphthalmology,OtorhinolaringologyandHeadandNeckSurgery,FaculdadedeMedicinadeRibeirãoPreto,Universidade
deSãoPaulo(FMRP-USP),RibeirãoPreto,SP,Brazil
bDepartmentofMedicalClinical,FaculdadedeMedicinadeRibeirãoPreto,UniversidadedeSãoPaulo(FMRP-USP),RibeirãoPreto,SP,
Brazil
cDepartmentofGeneralandSpecializedNursing,EscoladeEnfermagemdeRibeirãoPreto,UniversidadedeSãoPaulo(EERP-USP),
RibeirãoPreto,SP,Brazil
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received3June2015 Accepted25October2015 Availableonline16January2016
Keywords: HLA AIDS Encephalitis T.gondii
a
b
s
t
r
a
c
t
Background/aims: ThefrequencyofHumanLeucocyteAntigens/allelesassociatedwithrapid
progressionfromHumanImmunodeficiencyVirusinfectiontoAcquiredImmunodeficiency SyndromewasevaluatedinBrazilianpatientswithAcquiredImmunodeficiencySyndrome withandwithoutToxoplasmicEncephalitis.
Methods:114patientswithAcquiredImmunodeficiencySyndrome(41withToxoplasmic
Encephalitis,43withanti-Toxoplasmagondiiantibodies,withoutToxoplasmic Eencephali-tis,and30withoutanti-ToxoplasmagondiiantibodiescirculatingandwithoutToxoplasmic Encephalitis)werestudied.
Results:HumanLeucocyteAntigens/allelesassociatedwithrapidprogressiontoAcquired
Immunodeficiency Syndrome, particularly HLA-B35, -DR3, and -DR1allele group, were significantly less represented in patients with Toxoplasmic Encephalitis and Acquired ImmunodeficiencySyndrome.
Conclusion: ThepresenceoftheseHumanLeucocyteAntigens/Alleles thatpredisposeto
AcquiredImmunodeficiencySyndromeprogressionwasassociatedwithresistanceto Tox-oplasmicEncephalitisamongHumanImmunodeficiencyVirus-1carriers.
©2016PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
∗ Correspondingauthorat:DepartmentofGeneralandSpecializedNursing,SchoolofNursingofRibeirãoPreto,UniversityofSãoPaulo,
3900Av.Bandeirantes,MonteAlegre,14049-902,RibeirãoPreto,SP,Brazil. E-mailaddress:[email protected](A.P.Fernandes).
http://dx.doi.org/10.1016/j.bjid.2015.10.010
1413-8670/© 2016 Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
116
braz j infect dis.2016;20(2):115–118Introduction
Humanleukocyteantigens(HLA)geneshavebeenreported tobeassociatedwithincreasedsusceptibility tothe devel-opment of specific disease or with progression to AIDS outcomes.1–3Theprogressionfromhumanimmunodeficiency
virus (HIV) infection to AIDS has been strongly associated withHLA-A1-Cw7-B8-DR3-DQ2 and HLA-A11-Cw4-B35-DR1-DQ1haplotypes,conferringahighriskofrapidprogressionto AIDS.4–7Ithasbeenassumedthatassociationsbetween
pro-gressiontoAIDSandparticularHLAallelesreflectdifferential antigenpresentationbyclasses IorIImoleculesexhibiting particularmotifsinthepeptidebindinggroove.8 For
exam-ple,themostharmfuleffectsofHLA-B*35areseenwiththe moleculesencoded bythe HLA-B*35:02 and B*35:03 alleles, whichhaveprolineatanchorposition2oftheirloaded pep-tideandanon-tyrosineresidueatposition9.9Forinstance,
theHLA-B*35:01 moleculecontainingtyrosine atposition9 does nothave any substantial effecton disease prognosis. WhilebothHLA-B*35subtypescanequallyinduceacytotoxic Tlymphocyte(CTL)response,viralloadwasclearedless effec-tively by non-tyrosine-containing HLA-B*35:02 and B*35:03 moleculescompared withHLA-B*35:01.10 Itmay,therefore,
bepossiblethatalteredepitoperecognitionbyHLA-B*35:02 andB*35:03willinduceCTLthatmaynotspecificallyfunction againstHIV-1-infectedcells.11
Toxoplasmagondiiinfectioniswidespreadinhumans,with
estimatedinfectionratesrangingfrom50%to80%ofthe gen-eralpopulationinSouthAmerica.12InsomeareasofSouthern
Brazil,theprevalenceofantibodiesagainstT.gondiimaybeas
highas98%.13,14Toxoplasmosisintheimmunocompromised
hostismostprobablyduetoreactivationofapreviouslatent infection and can belife-threatening.15 Encephalitisis the
mostimportantmanifestationoftoxoplasmosisin immuno-suppressedpatientsasitcausesseveredamageanddeath.16
ItisestimatedthatincountrieswithahighprevalenceofT.
gondii,toxoplasmicencephalitisisthemostcommoncerebral
lesioninHIVpatients.17
FewstudiesreportedanassociationbetweenHLA mark-ersand toxoplasmic encephalitisinAIDS patients.18–21 We
havepreviously reportedthat susceptibility to toxoplasmic retinochoroiditiswasassociatedwithHLAallelesrelatedwith rapidprogressionto AIDS,22 and the availability ofgenetic
markersforotherAIDSsevere complicationsmay discrimi-natepatientswithpoorprognosis.Tofurtherexplorewhether HLAmarkersassociatedwithrapidprogressiontoAIDScould also be associated with the development of toxoplasmic encephalitis,weevaluatedthesemarkersinBrazilianAIDS patientswithorwithouttoxoplasmicencephalitis.
Material
and
methods
PatientsThestudywasconductedon114adultHIV-infectedpatients (81 males)aged21–59 years (median=33) presentingAIDS, diagnosed 1–108 months (median=22) before inclusion in this study. Forty-one patients experienced toxoplasmic
encephalitis,diagnosedclinicallyandbybraincomputerized tomographyandbythepresenceofantibodyagainstT.gondii
(Group1).TwoadditionalAIDSpatientgroupswithout toxo-plasmicencephalitiswerestudied;i.e.,agroupof43patients withpositiveanti-Tgondiiantibodiesbutwithouttoxoplasmic encephalitis (Group 2), and 30 patients with neither
anti-T. gondiiantibodies nor toxoplasmicencephalitis(Group3).
PatientswereselectedfromtheAcquiredImmunodeficiency OutpatientClinicattheUniversityHospitaloftheFacultyof MedicineofRibeirãoPreto,UniversityofSãoPaulo,Brazil.A total of161healthy bonemarrow donorsfrom the Univer-sityHospitalofFacultyofMedicineofRibeirãoPretowithno knowninfectious,chronic,orautoimmunedisorderswerealso studied.
Ethicalaspects
ThelocalEthicsCommitteeoftheUniversityHospitalof Fac-ultyofMedicineofRibeirãoPretoandtheNationalBrazilian EthicsCommitteeapprovedthestudyprotocol,andinformed consent was obtainedfrom all individuals (HCFMRP-USP # 8992/2001andCONEP#203/2002).
Anti-T.gondiiantibodies
The search for anti-T. gondii antibodies in serum was per-formed by indirect immunofluorescence bythe methodof Camargo23 using an anti-human IgG fluorescentconjugate
(Bio-Meriéux).Serumsampleswith>1/16titerswere consid-eredtobepositive.
HLAtyping
HLAclassIantigensexpressedonthesurfaceofperipheral bloodlymphomononuclearcellsweretypedusinga microlym-phocytotoxity assay.24 DNA was obtained from peripheral
bloodmononuclearcellsusingasaltingoutprocedure.HLA class IIallele typing was performed using commercial kits (OneLambda,CanogaPark,CA),aspreviouslydescribed.25
HLAspecificitiesassociatedwiththerateofprogressionto AIDS
SinceHLA-A1,A11,B8,B35,DR3,DR1,DQ2,DQ1antigenshave beendescribedintheliteratureinassociationwithrapid pro-gression toAIDS4,26 inmany ethnic groups, thesemarkers
wereconsideredforanalysisinthepresentstudy.
Statisticalanalysis
HLAantigenandHLAallelegroupfrequencieswerecalculated bydirectcounting.Thestrengthoftheassociationbetween toxoplasmicencephalitisandHLAspecificitieswasevaluated calculating the relative risk (RR)and Odds Ratio (OR).The Fisher’sexacttestwasusedforcomparisons,anditwas con-sideredtobesignificantatp<0.05.
brazj infect dis.2016;20(2):115–118
117
Table1–Frequencyofhumanleukocyteantigens(HLA)associatedwithrapidprogressiontoAIDSinBrazilianAIDS patientspresentingwith:(i)toxoplasmicencephalitis(Group1);(ii)antibodyagainstT.gondiibutwithouttoxoplasmic encephalitis(Group2);and(iii)negativeserologyforT.gondiiandwithouttoxoplasmicencephalitis(Group3).The frequenciesofHLAamonghealthycontrolsarealsoshown.
HLA Group1(n=41) Group2(n=43) Group3(n=30) Healthycontrols (n=161)
GroupComparisons(p-values)
1×2 1×3 2×3 HLA-A11 4(10%) 2(5%) 2(7%) 19(12%) NS NS NS HLA-B35 4(10%) 6(14%) 14(47%) 76(47%) (p=0.0003×G1) NS 0.0007 0.0031 HLA-DR1 5(12%) 10(23%) 3(10%) 24(15%) NS NS NS HLA-DQ1 17(42%) 36(84%) 16(53%) 140(87%) (p=0.0001×G1) 0.0001 NS 0.008
NS,non-significantcomparisons;×G1,comparisonstoGroup1.
Results
HLAprofileaccordingtothepresenceoftoxoplasmic encephalitis
ThefrequencyofHLA-B35antigenwassignificantlydecreased among AIDS patients presenting toxoplasmic encephalitis (Group1)incomparisontoAIDSpatientswithneither
anti-T. gondiiantibodies nor toxoplasmic encephalitis(Group 3)
(p=0.0007),presentingaRR=0.20andanOD=0.12(Table1). Similarresultswere observedwhen thegroup of toxoplas-mic encephalitis AIDS patients (Group 1) were compared with healthy controls (p=0.0003) and a RR=0.20 and an OD=0.12 (Table 1). When the HLA-B35 antigen frequency wascomparedbetweenAIDS patientswithouttoxoplasmic encephalitis(Group 2 and Group 3) its frequency was sig-nificantly decreased amongAIDS patients presenting with anti-T.gondiiantibodies(Group2)(p=0.0031),withaRR=0.29 andanOD=0.18(Table1).However,the comparisonofthe frequencyofHLA-B35betweenpatientswithpositiveanti-T.
gondiiantibodies,withandwithout toxoplasmic
encephali-tis(Group1andGroup2),showednosignificantdifference (Table1).
Ontheother hand,thefrequencyofHLA-DQB1*01allele groupwassignificantlydecreasedamongAIDSpatient pre-senting toxoplasmic encephalitis (Group 1) in comparison to AIDS patient presenting anti-T. gondii antibodies but without toxoplasmic encephalitis(Group 2) p=0.0001),and with a RR=0.49 and an OD=0.13 (Table 1). Similar results were observed when the AIDS group with toxoplasmic encephalitis (Group 1) were compared with healthy con-trols(p=0.0001),withaRR=0.47andanOD=0.10(Table1).
WhentheHLA-DQB1*01allelegroupfrequencywascompared
between AIDS patients without toxoplasmic encephalitis (Group 2 and Group 3) its frequency was significantly decreased among those without anti-T. gondii antibodies (Group3)(p=0.008),conferring aRR=1.57 and anOD=4.50 (Table1).
The frequencies ofother HLA markers associated with rapidprogressiontoAIDSwere closelysimilaramongAIDS patientsandhealthycontrols.
Discussion
SeveralreportsexaminingtheroleofHLAantigens/allelesin AIDSsusceptibilityhavebeenpublished5andthehaplotypes
encompassingHLA-B35antigenswereconsistentlyassociated withrapidprogressiontoAIDSinseveralpopulations.27 HLA-B*35alleleshavebeenclassifiedintotwogroupsbasedonthe residueatpocket9(P9)ofthepeptidebindinggroove.ThePY groupbinds mainlytoatyrosine (Y)atP9,whereasthe Px grouphasapreferenceforsmallerhydrophobicresiduessuch asleucine,methionine,orvaline,anddoesnotbindtotyrosine
atP9.9HLA-B*35:02andB*35:03alleles,whichcodepartofthe
Pxgroup,havebeenassociatedwithanespeciallypoorHIV disease outcome.10 Thepossiblemechanismsforthis
asso-ciationremainunknown,butithasbeensuggestedthatthe greaterabilityoftheHLA-B*35:01(PY)moleculetopresentHIV peptides(Gag)comparedtoHLA-B*35:02/35:03moleculesisa keydifferenceaffectingHIVdiseaseoutcome.28Furthermore,
HLA-B35:16anothermemberofthePYgroup,wastheworst HIV-peptidebindingmoleculeamongallB35subtypesandwas associatedwiththehighestviralload.Therefore,the detri-mentaleffectofHLA-B35isunlikelytoberelatedexclusively toPY/Pxgroups.Otherfactors,suchasthefinespecificityof theHIVpeptidespresentedbydifferentB35molecules,may playarole,affectingthenatureoftheCTLresponse.29
FewstudieshavefocusedontheevaluationofHLA anti-gens/alleles intoxoplasmicinfection amongAIDS patients. Concerningcerebraltoxoplasmosis,the studyconductedin CaucasianNorthAmericanpatientswithAIDShavereported an association of the HLA-DQ3 antigen with susceptibil-ity, and HLA-DQ1 antigen with resistance to toxoplasmic encephalitis.19,20 In the present study, we found a similar
association;i.e.,HLA-DQ1conferringresistanceto toxoplas-micencephalitisinBrazilianAIDSpatients.Additionally,Mack etal.studyingtransgenicmiceforDQhumangenes, demon-stratedthatthehumanDQB1gene,andtoalesserextentDQ3
gene, confersprotectionagainstT. gondii,corroborating the ideathatcertainDQB1genesareassociatedwithprotection againstthispathogenicprotozoan.
This is the first study evaluating the frequency ofHLA markers in Brazilian AIDS patients, a mixed population,
118
braz j infect dis.2016;20(2):115–118presentingwith cerebraltoxoplasmic disease.Thefindings suggestthatthefrequencyofHLAmarkersassociatedwith rapidprogressiontoAIDS,inparticulartheHLA-DQB1*01allele groupandHLA-B35antigen,werelessrepresentedamong tox-oplasmicencephalitisAIDSpatients.ThefrequencyofT.gondii
infectioninBrazilianAIDSpatientscanbeashighas98%.13
Therefore, the presence ofthese HLAmarkers may confer resistancetothe developmentoftoxoplasmic encephalitis, whicharedifferentfromthosemarkersassociatedwithrapid progressiontoAIDS.
Inconclusion,AIDSpatientspresentingHLA-DQBl*01allele groupappeartoberesistanttothedevelopmentof toxoplas-micencephalitis,sincethefrequencyofthisallelewaslower inAIDSpatientspresentingencephalitisinrelationtoAIDS patientspresentingonlytheinfection(anti-T.gondii antibod-ies).ThepresentstudysuggeststhatHLA-DQB1typing,better thantheHLA-B,mayhelpondecisionsregarding toxoplasmo-sisprophylaxis.Furtherstudieswillberequiredtodetermine ifgeneticcontrolofsusceptibilitytotoxoplasmicencephalitis issimilarinAIDSpatientsofotherethnicities.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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