人類基因多態(tài)性與移植后巨細(xì)胞病毒感染相關(guān)性研究進(jìn)展

魏巴金 周琳

·綜述·

人類基因多態(tài)性與移植后巨細(xì)胞病毒感染相關(guān)性研究進(jìn)展

魏巴金1, 2周琳1

CMV是一種皰疹DNA病毒，一般正常人群可以攜帶，但不引起臨床癥狀。移植后合并CMV感染在供者CMV陽性而受者CMV陰性(D+/R-)時(shí)發(fā)生率較高，輕者可能引起輕微無癥狀感染，重者可能引起嚴(yán)重器官功能衰竭甚至死亡。常見的預(yù)防措施因?yàn)樗幬锊涣挤磻?yīng)和經(jīng)濟(jì)問題而無法全面應(yīng)用。在過去的10年里，有很多探討人類基因多態(tài)性和移植后CMV感染、再燃和相關(guān)組織疾病等之間關(guān)系的研究，但結(jié)果并不一致。本文系統(tǒng)地闡述了目前人類基因多態(tài)性與移植后CMV感染的相關(guān)性研究，并根據(jù)移植類型(包括肝移植、腎移植、心肺移植、造血干細(xì)胞移植和實(shí)體器官移植)，有助于掌握目前的研究進(jìn)展，為未來研究方向提供一定的參考。

基因多態(tài)性； 巨細(xì)胞病毒； 移植

移植術(shù)后出于保護(hù)移植物的需要，往往需要人為降低受者本身的免疫系統(tǒng)功能應(yīng)答，增加了許多病毒、細(xì)菌、真菌等感染的風(fēng)險(xiǎn)。CMV是一種皰疹DNA病毒，一般正常人群可以攜帶，但不引起臨床癥狀。移植術(shù)后CMV感染在供者CMV陽性而受者陰性(D+/R-)時(shí)發(fā)生率較高，輕者可能引起輕微無癥狀感染，重者可能引起嚴(yán)重器官功能衰竭甚至死亡[1-2]。目前，CMV感染及其發(fā)病機(jī)制尚不明確，常見的預(yù)防措施有移植術(shù)前預(yù)防性使用藥物，但這不僅加重了患者負(fù)擔(dān)，而且存在白細(xì)胞、血小板減少和發(fā)熱等不良反應(yīng)[1, 3]。

人類基因多態(tài)性是進(jìn)化的動(dòng)力，但也為疾病的治療帶來了一定困難。目前研究表明，人類基因多態(tài)性對移植受者術(shù)后CMV易感性、CMV感染臨床表現(xiàn)的多樣性以及對藥物治療的反應(yīng)上都起著重要作用；人類基因多態(tài)性與移植術(shù)后CMV感染的相關(guān)性研究對認(rèn)識(shí)該疾病的發(fā)病機(jī)制、預(yù)測轉(zhuǎn)歸等方面有重要作用。如何精準(zhǔn)地使用抗病毒藥物，實(shí)現(xiàn)個(gè)體化治療，已成為移植領(lǐng)域的一大研究熱點(diǎn)。

1 肝移植

2007年，Kijpittayarit等[4]首先報(bào)道，與不具有Toll樣受體2(toll-like receptor 2，TLR2)位點(diǎn)rs5743708基因多態(tài)性的肝移植受者相比，具有該位點(diǎn)基因多態(tài)性的純合子和雜合子具有更高的CMV DNA復(fù)制量，且單因素分析指出其是CMV病的危險(xiǎn)因素；但在多因素分析中，通過對年齡、急性排斥反應(yīng)、感染狀態(tài)等因子校正后，二者相關(guān)性存在不確定性。2012年，另一項(xiàng)涉及737例肝移植受者的研究卻指出，TLR2(位點(diǎn)rs5743708)純合子基因型的受者術(shù)后組織侵襲性CMV病的發(fā)生率升高[5]。無論供者或受者術(shù)前是否存在CMV感染，供者甘露糖結(jié)合凝集素(mannose-binding lectin，MBL)和膠原凝集素2基因多態(tài)性可以獨(dú)立預(yù)測CMV感染，特別是在供者CMV陰性而受者陽性(D-/R+)情況下預(yù)測作用更佳，結(jié)合供、受者基因型不一致狀態(tài)可以增加預(yù)測能力[6]。在活體肝移植中，細(xì)胞色素P450 3A5(cytochrome P450 3A5，CYP3A5)表達(dá)型肝移植受者發(fā)生CMV和細(xì)菌感染的可能性和ImmuKnow檢測免疫細(xì)胞功能的結(jié)果明顯高于非表達(dá)型[7]。IL28B(位點(diǎn)rs12979860)基因多態(tài)性被證實(shí)不僅對急性排斥反應(yīng)有影響，而且與CMV的再燃也有相關(guān)性[8]。

2 腎移植

法國一項(xiàng)研究指出，如果將具有TLR4位點(diǎn)rs4986790和rs4986791任何變異型的腎移植受者定義為變異型攜帶者，與野生型攜帶受者相比，CMV感染可能會(huì)有較高，但結(jié)果差異不具有統(tǒng)計(jì)學(xué)意義[9]。白介素家族成員基因多態(tài)性與CMV感染的關(guān)聯(lián)也有較多相關(guān)研究。供者IL10位點(diǎn)rs1800896 AA基因型可以降低受者術(shù)后CMV感染率并延遲感染發(fā)生時(shí)間，受者該基因型基因多態(tài)性則與是否感染CMV沒有關(guān)系[10]。法國Hoffmann等[11]另一項(xiàng)研究發(fā)現(xiàn)，經(jīng)過多因素分析，具有IL12位點(diǎn)rs3212227等位基因C可以增加CMV感染，這種相關(guān)性在移植前CMV陽性且未接受預(yù)防性治療的受者中更加明顯。在接下來的實(shí)驗(yàn)中，雖然未能驗(yàn)證IL12位點(diǎn)rs3212227基因多態(tài)性和腎移植術(shù)后急性排斥反應(yīng)、慢性移植物失功和移植物生存有關(guān)，卻再次發(fā)現(xiàn)具有位點(diǎn)rs3212227等位基因C受者發(fā)生CMV感染的風(fēng)險(xiǎn)增加[12]。進(jìn)一步研究PD-1基因多態(tài)性與CMV感染的關(guān)系，Hoffmann等[13]還發(fā)現(xiàn)該基因位點(diǎn)rs11568821等位基因A與IL12基因3-UTR區(qū)域的基因多態(tài)性相比，具有更好的預(yù)測CMV感染的能力。具有IL28B位點(diǎn)rs12979860等位基因T的腎移植受者CMV感染風(fēng)險(xiǎn)降低34%，在術(shù)前不采取預(yù)防措施的亞組分析中，TLR9位點(diǎn)rs5743836 TT基因型同樣被發(fā)現(xiàn)對CMV感染具有保護(hù)作用，而樹突狀細(xì)胞特異性細(xì)胞黏附分子-3結(jié)合非整合素因子(dendritic cell specific intercellular-adhesionmolecule-3 grabbing non-integrin，DC-SIGN)位點(diǎn)rs735240GG基因型卻被視為危險(xiǎn)因素[14]。有關(guān)細(xì)胞因子IFN-γ(位點(diǎn)rs2430561)單因素分析表明，相對于TT基因型，AA基因型攜帶者CMV感染風(fēng)險(xiǎn)增加約3.4倍；多因素分析指出：D+/R-、位點(diǎn)rs2430561的基因多態(tài)性、急性排斥反應(yīng)和使用抗胸腺細(xì)胞球蛋白誘導(dǎo)可以作為CMV感染的高危因素[15]。兩項(xiàng)針對不同地區(qū)人群開展的研究同時(shí)指出，在中國西北部和印度腎移植受者中，HLA-G啟動(dòng)子一段14 bp的缺失會(huì)同時(shí)影響CMV感染和急性排斥反應(yīng)的發(fā)生情況[16-17]。一項(xiàng)關(guān)于腎移植術(shù)后早期3個(gè)月受者CMV感染的研究指出，維生素D受體位點(diǎn)FokIff基因型攜帶者CMV病的發(fā)生率會(huì)升高[18]。相比無癥狀CMV感染患者，細(xì)胞毒性T淋巴細(xì)胞相關(guān)抗原4(cytotoxic T lymphocyte antigen-4，CTLA4)(位點(diǎn)rs231775和rs3087243)GG基因型在有癥狀的CMV感染患者中頻率較高，它的存在可以使CMV感染出現(xiàn)癥狀的風(fēng)險(xiǎn)增加約2.5倍[19]。

3 心肺移植

IFN-γ位點(diǎn)rs2430561 TT基因型的肺移植受者不僅IFN-γ分泌增加，而且和CMV病發(fā)展相關(guān)，特別是在CMV陽性受者中更加明顯，同時(shí)也降低了血CMV載量的峰值[20]。奧地利一項(xiàng)關(guān)于肺移植的研究中，研究人員發(fā)現(xiàn)人CMV特異性免疫球蛋白表達(dá)和移植后巨細(xì)胞病毒復(fù)制密切相關(guān)，并且通過測定44位患者的免疫球蛋白重鏈γ1的基因多態(tài)性，認(rèn)為其影響人CMV特異性免疫球蛋白表達(dá)[21]。Gourley等[22]在心臟移植研究中發(fā)現(xiàn)，TNF-α、TNF-β、IL-6、IL-10、IFN-γ的基因多態(tài)性和CMV感染無相關(guān)性。

4 造血干細(xì)胞移植

德國一項(xiàng)針對43例造血干細(xì)胞移植受者的研究中，趨化因子受體5(chemokine receptor 5，CCR5)和IL10的基因多態(tài)性被認(rèn)為和CMV病病情發(fā)展有關(guān)，而單核細(xì)胞趨化蛋白-1(monocyte chemotactic protein 1，MCP-1)則和CMV的再燃有關(guān)[23]。Corrales等[24]對102例西班牙造血干細(xì)胞移植受者的研究發(fā)現(xiàn)，雖然受者和供者CCR5(位點(diǎn)rs1800023)、MCP-1(位點(diǎn)rs13900)、IL-10(位點(diǎn)rs1878672)及TLR9(位點(diǎn)rs352140)基因多態(tài)性和CMV的活動(dòng)性無明顯聯(lián)系，但是供者CCR5位點(diǎn)rs1800023 AA基因型攜帶者CMV血癥和血漿中CMV DNA峰值持續(xù)時(shí)間較長。DC-SIGN基因啟動(dòng)子區(qū)域的(位點(diǎn)rs735240和rs2287886)基因多態(tài)性可以影響DC-SIGN基因的表達(dá)，從而影響樹突狀細(xì)胞對CMV的免疫作用，和CMV再燃、CMV病密切相關(guān)[25]。和肺移植、腎移植一樣，行造血干細(xì)胞移植后IFN-γ的基因多態(tài)性和CMV病再發(fā)、高病毒載量有關(guān)，而CMV拷貝數(shù)高往往伴隨宿主急性移植物排斥反應(yīng)，并且預(yù)后較差[26]。供者CTLA4(位點(diǎn)rs3087243)的AA基因型更易在異基因造血干細(xì)胞移植的早期出現(xiàn)CMV感染以及反復(fù)發(fā)作，并且和預(yù)后呈現(xiàn)一定的相關(guān)性[27]。造血干細(xì)胞移植并出現(xiàn)過移植物排斥反應(yīng)的受者，其共刺激分子中的CLTA4(位點(diǎn)rs4553808)和CD28(位點(diǎn)rs3116496)基因多態(tài)性與活動(dòng)性CMV感染相關(guān)[28]。雖然造血干細(xì)胞移植受者和供者IL28B(位點(diǎn)rs8099917)基因多態(tài)性和活動(dòng)性CMV感染無明顯關(guān)聯(lián)，但供者TT基因型會(huì)有較短的血CMV DNA持續(xù)時(shí)間[29]。在接受異基因造血干細(xì)胞移植的兒童白血病患者中擁有核轉(zhuǎn)錄因子FOXP3位點(diǎn)rs3761548的等位基因CC攜帶者CMV感染發(fā)生率較高，同時(shí)肝靜脈閉塞性疾病風(fēng)險(xiǎn)也會(huì)提高，并且生存時(shí)間較短[30]。

5 實(shí)體器官移植

在檢測MBL的3個(gè)功能基因多態(tài)性位點(diǎn)后，發(fā)現(xiàn)其單倍型全部為純合子狀態(tài)，和侵襲性CMV病密切相關(guān)，相比非純合子受者，發(fā)生該疾病的風(fēng)險(xiǎn)提高了約6倍[31]。D+/R-實(shí)體器官移植受者IL28B位點(diǎn)rs8099917 TT基因型攜帶者會(huì)有較高的CMV DNA復(fù)制量，并且體外實(shí)驗(yàn)證明，該位點(diǎn)在CMV的刺激下會(huì)影響IL28B的表達(dá)[32]。IL28B基因可以編碼IFN，IFN基因位點(diǎn)rs368234815多態(tài)性包括基因型TT/TT、基因型-G/-G及二者的雜合子，基因型-G/-G攜帶者CMV DNA復(fù)制量更高，在供者CMV陽性的受者中尤為明顯[33]。MCP-2分泌和器官移植后CMV感染密切相關(guān)，且停止預(yù)防性用藥后，在MCP-2啟動(dòng)子區(qū)域位點(diǎn)rs3138035 TT基因型的D+/R-受者群體中會(huì)出現(xiàn)CMV復(fù)制[34]。

6 總 結(jié)

目前有關(guān)人類基因多態(tài)性和移植后CMV感染的相關(guān)研究主要集中在細(xì)胞因子(如IL和IFN家族等)，樣本量相對較少，取得的結(jié)果存在一定的局限性，尚不能大規(guī)模應(yīng)用于臨床。特別是存在相同基因位點(diǎn)在不同的移植研究中出現(xiàn)不同結(jié)果，可能是由各種族和疾病評判標(biāo)準(zhǔn)的差異引起，需要進(jìn)一步的薈萃分析等手段來增加證據(jù)的信度。此外，基因多態(tài)性檢測費(fèi)用雖然較以前有大幅度的下降，但廣泛應(yīng)用于臨床尚有一定的距離。可以預(yù)見基因多態(tài)性會(huì)在臨床個(gè)體化治療應(yīng)用中發(fā)揮重要作用。隨著中國人體器官分配與共享系統(tǒng)等相關(guān)協(xié)作登記制度的完善，開展大規(guī)模人群研究的障礙逐步減少，基因多態(tài)性的檢測技術(shù)也日新月異，未來多中心、大樣本試驗(yàn)將會(huì)陸續(xù)開展。

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(本文編輯：徐小明)

魏巴金, 周琳. 人類基因多態(tài)性與移植后巨細(xì)胞病毒感染相關(guān)性研究進(jìn)展[J/CD]. 中華移植雜志: 電子版, 2016, 10(1):45-48.

Progress on the association between human gene polymorphisms and cytomegalovirus infection after transplantation

WeiBajin1,2,ZhouLin1.1KeyLaboratoryofOrganTransplantation,2DiagnosisandTreatmentofBreastDiseasesCenter,theFirstAffiliatedHospital,SchoolofMedicine,ZhejiangUniversity,Hangzhou310003,China

ZhouLin,Email：linzhou19@163.com

Cytomegalovirus belonged to herpes virus group, which could be carried by health people. The patients with transplantation often suffered from the deficiency of innate and adaptive immune. Therefore, cytomegalovirus relative diseases were extremely common after transplantation, especially in (D+R-/D-R+) group. The clinical outcomes fluctuated between mild asymptomatic infection and multiple organ dysfunction syndromes. The benefit of prophylactic anti-virus drugs should be measured before transplantation for their own limitations (adverse side effects and financial burdens).In the past 10 years, many single nucleotide polymorphisms in human genes had been analyzed to explore their relationships with cytomegalovirus infection, reactivation and tissue relative diseases, but the results were not consistent. Our study tried to illustrate and classify those associations by genes and transplantations. It would help to understand the progress of current researches and show the potential direction in the future.

Gene polymorphisms; Cytomegalovirus; Transplantation

10.3877/cma.j.issn.1674-3903.2016.01.009

310003 杭州，浙江大學(xué)醫(yī)學(xué)院附屬第一醫(yī)院器官移植重點(diǎn)實(shí)驗(yàn)室1,乳腺疾病診治中心2

周琳, Email: linzhou19@163.com

2016-01-16)