Table_1_Histologic and Molecular Patterns in Responders and Non-responders With Chronic-Active Antibody-Mediated Rejection in Kidney Transplants.docx

IntroductionThere is no proven therapy for chronic-active antibody-mediated rejection (caABMR), the major cause of late kidney allograft failure. Histological and molecular patterns associated with possible therapy responsiveness are not known.
MethodsBased on rigorous selection criteria this single center, retrospective study identified 16 out of 1027 consecutive kidney transplant biopsies taken between 2008 and 2016 with pure, unquestionable caABMR, without other pathologic features. The change in estimated GFR pre- and post-biopsy/treatment were utilized to differentiate subjects into responders and non-responders. Gene sets reflecting active immune processes of caABMR were defined a priori, including endothelial, inflammatory, cellular, interferon gamma (IFNg) and calcineurin inhibitor (CNI) related-genes based on the literature. Transcript measurements were performed in RNA extracted from stored, formalin-fixed, paraffin-embedded (FFPE) samples using NanoString™ technology. Histology and gene expression patterns of responders and non-responders were compared.
ResultsA reductionist approach applying very tight criteria to identify caABMR and treatment response excluded the vast majority of clinical ABMR cases. Only 16 out of 139 cases with a written diagnosis of chronic rejection fulfilled the caABMR criteria. Histological associations with therapy response included a lower peritubular capillaritis score (p = 0.028) along with less glomerulitis. In contrast, no single gene discriminated responders from non-responders. Activated genes associated with NK cells and endothelial cells suggested lack of treatment response.
ConclusionIn caABMR active microvascular injury, in particular peritubular capillaritis, differentiates treatment responders from non-responders. Transcriptome changes in NK cell and endothelial cell associated genes may further help to identify treatment response. Future prospective studies will be needed which include more subjects, who receive standardized treatment protocols to identify biomarkers for treatment response.
Clinical Trial Registration[ClinicalTrials.gov], identifier [NCT03430414].

引言
目前尚无针对慢性活动性抗体介导排斥反应（chronic-active antibody-mediated rejection, caABMR）的公认治疗方案，而该疾病是晚期肾移植失功的主要诱因。目前尚不清楚与潜在治疗应答相关的组织学及分子特征。

方法
本项单中心回顾性研究基于严格的筛选标准，从2008年至2016年间收集的1027例连续肾移植活检标本中，筛选出16例仅存在单纯、明确的caABMR、无其他病理特征的病例。通过对比活检/治疗前后的估算肾小球滤过率（estimated glomerular filtration rate, eGFR）变化量，将研究对象划分为治疗应答者与无应答者。基于既往文献，我们预先设定了反映caABMR活动性免疫过程的基因集，包括内皮细胞相关、炎症相关、细胞相关、γ干扰素（interferon gamma, IFNg）及钙调磷酸酶抑制剂（calcineurin inhibitor, CNI）相关基因。采用NanoString™技术，对储存的福尔马林固定石蜡包埋（formalin-fixed paraffin-embedded, FFPE）标本提取的RNA进行转录本检测，并对比应答者与无应答者的组织学特征及基因表达模式。

结果
本研究采用严格筛选caABMR及治疗应答的简约化研究策略，排除了绝大多数临床抗体介导排斥反应（antibody-mediated rejection, ABMR）病例。在139例被书面诊断为慢性排斥反应的病例中，仅16例符合caABMR标准。与治疗应答相关的组织学特征包括较低的肾小管周毛细血管炎评分（p=0.028）及较轻的肾小球炎表现。与之相反，无单个基因可有效区分应答者与无应答者。与自然杀伤细胞（natural killer cell, NK）及内皮细胞相关的活化基因，提示治疗无应答。

结论
在caABMR中，活动性微血管损伤（尤其是肾小管周毛细血管炎）可区分治疗应答者与无应答者。NK细胞及内皮细胞相关基因的转录组变化，或可进一步辅助识别治疗应答情况。未来需开展纳入更多研究对象、采用标准化治疗方案的前瞻性研究，以筛选治疗应答相关生物标志物。

临床试验注册
[ClinicalTrials.gov]，标识符[NCT03430414]。