Granulin specific monoclonal antibodies to investigate their expression and role

描述（由申请人提供）：美国有超过700万例痴呆症病例（约占人口的3%），其中约5%是额颞叶痴呆症（FTD）。最近已证实，美国所有FTD的5-10%是由颗粒蛋白原（PGRN）基因突变引起的。这伴随着患者生物体液中PGRN水平降低50%。PGRN是一种由593个氨基酸组成的生长和存活因子。克隆和测序结果表明，PGRN含有一个17个氨基酸的分泌信号肽和7.5个6 kDa的grn重复序列，并具有一个独特的串联重复双半胱氨酰富含颗粒蛋白（grn）基序。6 Kda Grn是通过弹性蛋白酶刺激的蛋白水解切割加工PGRN产生的，并被分泌性白细胞蛋白酶抑制剂SLPI阻断。最近的证据表明，PGRN和grns都可能直接影响神经退行性疾病的过程，如阿尔茨海默病，帕金森病和某些类型的FTD。已经表明PGRN和grn水平的平衡对于作为炎症结果的神经元保护/降解是重要的。因此，PGRN和grn水平的测量可以揭示脑中正常与疾病相关过程的平衡。目前，与PGRN相比，对脑中特定grn的功能和表达以及将PGRN和grn与这些疾病联系起来的可能机制知之甚少。因此，开发特定的经验证的测定系统以推进PGRN/grn领域在神经退行性疾病中的发展是至关重要的。主要研究者是公认的PGRN研究专家，特别是在癌症领域，并开发了经临床验证的高质量单克隆抗体和测定方法，以测量患者组织和生物体液中的PGRN。她的PGRN检测和试剂也用于与两个卓越的神经退行性疾病中心的合作研究。然而，目前还没有可靠、灵敏和特异的方法来检测grn分子，从而阻碍了对grn在神经退行性疾病中作用的理解。主要研究者请求在该RO 3申请中提供支持，以开发一系列对grn具有特异性的单克隆抗体。该方法将靶向七种不同grn的新切割位点，以开发适用于7种grn中每一种的夹心ELISA测定的mAb。具体地，提出：1）开发对7种grn分子中的每一种具有特异性的高亲和力mAb，其适用于生物样品中的夹心ELISA检测; 2）开发标准化实验室测定，用于特异性检测浓度小于100 pg/ml且不受PGRN干扰的生物流体中的7种grn。这些研究将是重要的，因为开发了针对7种grns中每一种的经验证的夹心ELISA试剂盒，它将使研究人员能够调查各种grns的存在和比例。 来自神经退行性疾病患者（如FTD）的CSF和其他生物样本中的grns和PGRN。提供可以检测、测量和阐明这些重要生物制品的作用的工具也可能有助于揭示将它们用作疾病或治疗监测的治疗靶点或替代标志物的潜力。

DESCRIPTION (provided by applicant): Over 7 million cases of dementia exist in the US (~3% of the population) and of these ~5% are frontotemporal dementia (FTD). It has been demonstrated recently that 5-10% of all FTD in the US are caused by mutations in the Progranulin (PGRN) gene. This is accompanied with a 50% reduction of PGRN level in patients' biological fluids. PGRN is a 593 amino-acid growth and survival factor. Cloning and sequencing of PGRN showed that it contains a 17 amino-acid signal peptide for secretion and seven and a half 6 kDa grn repeats with a unique tandem repeat double cysteinyl rich granulin (grn) motif. The 6 Kda Grns are generated by processing of PGRN by a proteolytic cleavage stimulated by elastase and blocked by secretory leucocyte protease inhibitor SLPI. Recent evidence suggests that both PGRN and grns may directly influence neurodegenerative diseases process, such as Alzheimer's disease, Parkinson's disease and certain types of FTD. It has been suggested that the balance of PGRN and grn levels is important for neuron protection/degradation as a result of inflammation. Accordingly, the measurement of PGRN and grn levels may shed light on the balance of normal versus disease related processes in the brain. Currently, relatively little is known about the function and expression of specific grns in the brain when compared to PGRN and about the possible mechanisms linking PGRN and grn to these diseases. Thus, it is critical to develop specific validated assay systems to advance the PGRN/grn field forward in the neurodegenerative disease. The principal investigator is a recognized expert in PGRN research particularly in cancer and has developed clinically validated high quality monoclonal antibodies and assays to measure PGRN in tissue and biological fluids in patients. Her PGRN assays and reagents are also used in collaborative studies with two centers of excellence in neurodegenerative disease. However, there are no reliable, sensitive and specific assays to measure grn molecules, thereby hampering understanding of the role of grns in neurodegenerative diseases. The principal investigator is requesting support in this RO3 application to develop a portfolio of monoclonal antibodies specific to grn. The approach will be to target the neo-cleavage sites of the seven different grns to develop mAbs suitable for sandwich ELISA assay for each of the 7 grns. Specifically, it is proposed to: 1) Develop high affinity mAbs specific to each of 7 grn molecule suitable for sandwich ELISA detection in biological samples: 2) Develop standardized laboratory assays for specifically detecting the 7 grns in biological fluids at concentrations of less than 100 pg/ml and without interference by PGRN. These studies will be important as the development of validated sandwich ELISA kits for each of the 7 grns, it will enable researchers to investigate the presence and the ratio of various grns and PGRN in CSF and other biological samples from patients with neurodegenerative diseases such as FTD. Providing tools that can detect measure and elucidate the role of these important biological products may also be useful in revealing the potential to use them as therapeutic targets or surrogate markers for disease or therapy monitoring.