【作者】 王平贤；

【导师】 金锡御；

【作者基本信息】 第三军医大学 ， 外科学， 2004， 博士

【摘要】 由于免疫抑制剂的发展，特别是环孢素A（CsA）应用于临床，同种异体肾移植急性排斥反应的发生率和严重程度都已明显降低，肾移植近期效果得到了显著改善。然而，尽管应用了预防急性排斥反应足量的免疫抑制剂，肾移植远期效果却未能得以相应的提高，移植肾的平均半寿期（half-life）仍只有在7-10年，这主要是因为以间质纤维化为特点的慢性移植物肾病（CAN）缓慢而进行性地损害了移植肾，最终导致肾功能衰竭、患者恢复透析。CAN是目前移植肾长期存活的主要障碍和肾移植1年后移植物功能丧失的主要原因。CAN最基本的病理改变为细胞外基质沉积、间质纤维化。许多免疫和非免疫因素都可以导致CAN。在引起CAN的众多病因中，近年来动物实验发现巨细胞病毒（CMV）感染可能是又一个重要的原因。 CMV为人类病毒感染中常见的病原体。60～90％的健康成人曾经感染过CMV。CMV是一种弱致病因子，对免疫力正常的个体不具有明显毒力，但一旦感染，CMV即终生潜伏于宿主体内。当免疫功能下降时，机体又可新感染CMV、或潜伏的病毒再次激活、复制，形成活动性CMV感染。CMV还可与其它病原体构成二重或多重感染，严重时感染者死亡率高。 肾移植后早期由于应用了大剂量免疫抑制剂，患者术后发生活动性CMV感染高达60-80％，为此，CMV感染被认为不仅是肾移植受者术后近期死亡的重要原因，更重要的是它可能与远期慢性移植物失功有关，肾移植后能否有效、及时地防治CMV感染可能是影响移植效果的关键。 在正常情况下，只要血清抗CMV-IgM为阳性，或抗CMV-IgG由阴性转为阳性或双份血清显示抗CMV-IgG滴度升高4倍以上，即可诊为活动性CMV感染。然而，由于肾移植患者术后应用了大剂量的免疫抑制剂，其抗体反应弱而迟钝，在这个特殊的群体中，依靠血清学检查已不能做出正确的诊断。为了克服这一困难，近年来检测CMV-pp65抗原血症以判断体内有无活动性CMV感染正逐渐应用于临床。CMV-pp65为病毒的结构蛋白，它的出现是活动性CMV感染的标志。CMV-pp65抗原血症检测还可提供定量结果，抗原血症的强度可以反映机体内病毒的负荷、CMV感染的严重程度和抗病毒治疗效果等。 慢性移植物肾病（CAN）最基本的病理改变为间质纤维化。TGF-β₁是一个关键的纤第三军医大学博士学位论文维发生因子，它通过刺激细胞外基质（胶元、蛋白多糖、纤维连接蛋白等）的合成、提高整合素（integrin）表达、降低基质降解蛋白酶的活性、调节细胞的生长分化、趋化成纤维细胞、促进某些间质细胞的增殖等，在组织的纤维化过程中起着重要的作用。TGF-pl的过度产生，在众多疾病中、特别是肾脏病中引起不可逆的组织纤维化。 目前，临床上肾移植患者术前活动性CMV感染的发生状况及其对术后CMV感染的影响、特别是 CMV感染与慢性移植物肾病的关系等问题尚未明了。虽然现在国内外对肾移植受者CMV感染的研究较多，但在临床上从CMV一pp65抗原血症定量分析的角度，研究肾移植受者术后早期不同cMv一pp65抗原血症水平与远期慢性移植物肾病（CAN）的关系至今尚未见文献报道。本研究的目的在于:①明确肾移植患者术前活动性CMV感染的发生状况及其对术后CMV感染的影响;②明确肾移植后早期活动性cMv感染是否与远期发生的慢性移植物肾病有关联、或者是哪种类型（即不同cMv一PP65抗原血症水平）的CMV感染才会导致慢性移植物肾病（C AN）的发生。③从CMv一pp65抗原血症水平上进一步明确肾移植后活动性CMV感染的发生规律。 该研究采用新桥医院1999年8月一2001年3月期间首次进行肾移植手术的217例患者为对象，术前检测患者血清抗CMV抗体和CMV一pp65抗原血症;术后对CMV一pp65抗原血症动态观察6个月;根据术后cMv一pp65抗原血症的水平和持续时间对CMV感染的严重程度进行量化、分组，对部分CMV感染严重的患者给予抗CMV治疗、或使用血管紧张素H受体拮抗剂抑制肾内TGF一p;的合成和分泌;对各组患者进行3年以上的前瞻性观察;对移植肾进行穿刺活检，明确不同类型CMV感染对移植肾内关键的纤维发生因子TGF一p lmRNA和蛋白表达的影响;检测血、尿TGF一pl浓度，明确血、尿TGF一p，浓度与远期肾功能的关系等。 通过对200多例患者前后共长达四年多的密切观察、对大量的临床移植肾穿刺标本的直接研究，本实验得出如下结论: 1、’肾移植前不仅患者CMV感染率高，而且有12.4%的患者存在着活动性CMV感染; 2、’肾移植患者术后6个月内，活动性CMV感染者发生率高达87.1%; 3、肾移植前活动性CMV感染，是导致肾移植后发生高活动性CMV感染和CMV病的重要原因; 4、在肾移植后最初6个月内，长时间高活动性CMV感染是导致移植肾远期功能损害、引起慢性移植物肾病的重要原因，而短时间高活动性CMV感染或长时间低活动性CMV感染均不会导致上述结果;第三军医大学博士学位论文 5、长时间高活动性CMV感染在导致移植肾远期功能损害的过程中，TGF一p;起着重要的介导作用; 6、对CMV感染严重的患者，如及时给予抗CMV治疗，或使用血管紧张素H受体拮抗剂抑制肾内TGF一pl的产生，均能有效地减少肾内TGF一pl的分泌和远期慢性移植物肾病(CA更多还原

【Abstract】 Recent improvements in immunosuppression have led to a dramatic increase in short-term renal allograft survival. However, though irnmunosuppressive agents which are sufficient to prevent acute rejection have been used, so-far the long-term result of renal transplant has not improved correspondingly. The rate of graft loss in the late posttransplantation period has remained virtually unchanged. The average half-life of a transplanted kidney is still 7-10 years. It is common that that renal function becomes depleted and dialysis is resumed, one or several years after transplantation. The reasons that have caused this phenomenon are not clear. Pathological investigation has shown that this kind of kidney has obvious scar trend. The allografts demonstrate extracellular matrix deposition, interstitial fibrosis and renal tubule atrophy on pathology. But all of the pathologic alterations are nonspecific. A lot of immunity and non-immune factors may finally cause the changes mentioned above. Depending simply on the pathologic alterations, it is very difficult to determine the reasons for the pathologic alterations. For this reason, the term "chronic allograft nephropathy (CAN)" which does not refer to etiological factors is used to define all the clinical disorders above-mentioned. CAN is the principal cause of late graft loss after the first year of renal transplantation. However, in recent years animals’ experiments show that CMV infection is also an important cause of CAN. It was found that CMV infection accelerates and enhances histologic changes in CAN, especially interstitial fibrosis and collagen synthesis, in a rat model of renal transplantation.Cytomegalovirus (CMV) is a common virus pathogen which infects human beings. The virus can invade into human bodies through multiple channels, such as respiratory track, digestive system, blood transfusion and organ transplantation, etc.. Epithelial cells, endothelial cells of blood vessels, and leukocytes in peripheral blood are extremely easy to be infected. 60-90% of healthy adults have been infected with CMV. Cytomegalovirus is a very weak poisonous pathogen for a healthy individual whose immunity is normal, but, once infected, the host will carry Cytomegalovirus for the remainder of his life. As theimmune function of an organism drops, especially when cellular immunity is low, the body can become infected by CMV newly, or the virus that was hidden in the body can be reactivated, duplicated again, and form active CMV infection. CMV often forms dual or multiple infections with other pathogens, the condition is critical, and infected individuals have high mortality.As heavy doses of immunosuppressive agents have been used in early post-transplant, active CMV infection is up to 60- 80%. 15-35% of those infections are CMV disease which shows some symptoms. For this reason, active CMV infection is considered not only the main cause for death of recipients early after kidney transplant, but it might also relate to the dysfunction of transplanted kidneys in the long term after transplantation. In order to get better results from kidney transplantation, prevention and treatment of active CMV infection effectively, and in time, may play an important role.Under the normal situation, so long as CMV-IgM can be found in serum, CMV-IgG becomes positive from negtive, or the concentration of CMV-IgG grows over four folds, the diagnosis of active CMV infection can be determined. However, as heavy doses of immunosuppressive agents have been used in early post-transplant, this kind of patient has had little ability to produce antibodies. Relying on serology tests can’t provide correct diagnosis for active CMV infection in this special group of people. In order to overcome the difficulty existing in diagnosis of active CMV infection, in recent years a new approach in which CMV-pp65 antigen in the leucocyte of periphery blood is detected has been clinically used to determine if active CMV infection exists. The antigen pp65 is a phosphoric acid protein formed by 561 pieces of amino a更多还原