Granzyme B PET imaging as a marker of inflammatory bowel disease activity

项目总结/摘要 炎症性肠病（IBD）是一组与显著发病率相关的炎症性疾病 对患者和社会的成本。由于缺乏治愈方法，治疗是针对控制肠道 使用抗炎剂和免疫抑制剂治疗炎症，这些药物已被证明可以大大改善 减少并发症。然而，这些疗法的使用应仅限于那些 由于高成本和严重不良事件（如严重感染、神经系统疾病）的风险， 疾病、心力衰竭和血液恶性肿瘤。内窥镜检查是目前首选的方法的疾病 活动评估与临床结果高度相关。然而，内窥镜的重复使用是有限的 由于其侵入性、难以给药和限制进入小肠。解剖成像很有帮助 但在早期反应评估、纤维狭窄的鉴别 疾病活动性炎症或预测疾病复发。分子成像目前尚不清楚 由于特异性欠佳且与临床指标缺乏相关性，因此在IBD中缺乏临床价值。的生物标志物 白细胞活性可能被证明是肠道炎症理想标志物和对治疗反应的预测。 这种生物标志物可以通过鉴定亚临床炎症以预防IBD的发生来显著推进IBD的管理。 与疾病相关的并发症，并降低与无效治疗相关的成本和副作用。 颗粒酶B（Gzm B）是细胞毒性淋巴细胞活性的标志物，其与疾病活动性强烈相关 在IBD。它由活化的淋巴细胞分泌到细胞外基质中， 通过处理促炎细胞因子的反应。我们已经开发了一种基于肽的PET成像剂， 68 Ga-NOTA-GZP，对活性GzmB具有高亲和力和特异性，并具有良好的成像生物分布 肠道炎症我们的初步数据表明，GZP PET摄取与肠道 在小鼠模型中的炎症，并且可以区分媒介物或抗TNF治疗的小鼠。在人体组织标本中 我们的人源化GZP（hGZP）探针强烈染色了活动性克罗恩病的炎症部位，而在 而正常人和静止期患者则无此现象。因此，GZP PET成像提供了一个独特的见解， 活动性炎症和早期反应的评估，目前使用其他技术是不可能的。 我们提出这项研究，以评估和优化一种新的诊断方法，用于评估疾病的活动性， IBD的早期治疗反应。为了验证人类翻译小鼠模型的发现，我们将 用常规组织病理学方法对人体组织标本进行离体hGZP染色。此外，我们将 优化用于快速检测小鼠模型粪便样本中GzmB的即时诊断测定， 在人体样本中验证。我们相信非侵入性评估活性GzmB代表了一种新的方法 用于重复评估IBD的疾病活动性和早期治疗反应，并有可能推进治疗 研究在不久的将来。

Project Summary/Abstract Inflammatory bowel disease (IBD) is a group of inflammatory disorders associated with significant morbidity and cost to the patients and society. With the absence of a cure, therapy is directed at control of intestinal inflammation using anti-inflammatory and immunosuppressive agents, which have been shown to vastly improve the outcomes and reduce complications. The use of these therapies, however, should only be limited to those with active disease due to high cost and risk of serious adverse events such as serious infections, neurologic disorders, heart failure, and hematologic malignancies. Endoscopy is currently the preferred method of disease activity assessment due to high correlation with clinical outcomes. However, repeated use of endoscopy is limited by its invasiveness, difficult administration, and restricted access to small bowel. Anatomical imaging is helpful in detection of active disease but has limited utility in early response assessment, differentiation of fibrostenotic disease from active inflammation or prediction of disease recurrence. Molecular imaging is currently of unclear clinical value in IBD due to suboptimal specificity and lack of correlation with clinical indices. A biomarker of leukocyte activity may prove to be ideal marker of intestinal inflammation and predictive of response to therapy. Such biomarker can significantly advance IBD management by identifying subclinical inflammation to prevent disease associated complications and reducing the cost and side effects associated with ineffective treatments. Granzyme B (GzmB) is a marker of cytotoxic lymphocyte activity which strongly correlates with disease activity in IBD. It is secreted in the extracellular matrix by activated lymphocytes and can mount a robust inflammatory response by processing proinflammatory cytokines. We have developed a peptide-based PET-imaging agent, 68Ga-NOTA-GZP, with high affinity and specificity for active GzmB and a favorable biodistribution for imaging intestinal inflammation. We have shown in our preliminary data that GZP PET uptake correlates with intestinal inflammation in mouse models and can differentiate vehicle or anti-TNF treated mice. In human tissue specimens of active Crohn’s disease our humanized GZP (hGZP) probe strongly stained the sites of inflammation, while in the normal subjects and quiescent disease did not. Thus, GZP PET imaging offers a unique insight into assessment of active inflammation and early response, not currently possible using other techniques. We propose this study to assess and optimize a novel diagnostic method for assessment of disease activity and early treatment response in IBD. To validate the findings in mouse models for human translation, we will correlate the ex vivo hGZP staining of human tissue specimens with conventional histopathology. Additionally, we will optimize a point of care diagnostic assay for rapid detection of GzmB in stool samples in mouse models and validate in human specimens. We believe non-invasive assessment of active GzmB represents a novel method for repeat assessment of disease activity and early treatment response in IBD with potential to advance care and research in the near future.