Implication of HUCBC: a novel therapeutic strategy for Alzheimer's disease

描述(申请人提供)：人脐血细胞(HUCBC)是众所周知的特异性免疫调节剂，能够平衡(即没有完全免疫抑制、移植物抗宿主病或排斥反应)改变外周和中枢免疫反应。其他研究人员已经证明，它们可以促进成人骨髓(BM)祖细胞的动员。此外，我们最近证实，来自输注HUCBC的PSAPP小鼠的血清显着抑制了由干扰素-？并显著增强小胶质细胞的吞噬活性，而不会造成不可接受的免疫损害。证实了CD40与CD40L蛋白的结合抑制了这种作用。重要的是，这些注射了HUCBC的小鼠的原代成年小胶质细胞也显示出增强的A？吞噬活性和强大的A？Ig G滴度。综上所述，这些数据表明，天然和体液免疫微环境的平衡改变是由HUCBC诱导的抑制CD40信号和增强A？IgG产生所介导的。与这种神经毒性先天反应的下调和有益体液反应的上调相一致，HUCBC体内注射降低了Aβ水平/淀粉样沉积和脑淀粉样血管病(CAA；血管淀粉样沉积的炎性反应)，伴随着：(A)血清A？1-40，42水平升高，提示A？1-40，42，提示中枢神经系统外流，(B)降低可溶性CD40L血清水平，(C)减少小胶质细胞CD40的表达，最后，(D)CNS/血清抗炎(IL-10和转化生长因子21)水平升高，促炎细胞因子(IL-1β和TNF-α)减少。最后，我们的初步数据表明，与对照原代BM来源的单核/巨噬细胞(MO/X)相比，注入HUCBC的PSAPP小鼠的MO/X显示出更强的A吞噬活性。这些数据，加上我们之前的发现，将Tg2576小鼠与CD40L缺失小鼠杂交，或用CD40L抗体处理PSAPP小鼠，可减少A？负荷，使我们推测HUCBC输注可缓解阿尔茨海默病(AD)小鼠的A？/？-淀粉样病变，其机制是CD40-CD40L中断导致BM来源的祖细胞MO/X动员起来，抗炎细胞因子的产生增加，淀粉样蛋白从大脑中清除。在这里，我们建议通过研究注入HUCBC的PSAPP小鼠的CD40信号来检验HUCBC介导的抑制CD40-CD40L相互作用减少淀粉样变性的假设。基于我们的初步数据，我们还计划通过单独和联合应用IL-10、转化生长因子β1和神经生长因子β来重建HUCBC输注的效果；我们发现这些关键因素是HUCBC在没有全身免疫抑制、排斥反应或GVHD的情况下调节CD40活性和淀粉样变性的能力所必需的。此外，我们还将验证这样一种假设，即输注HUCBC动员骨髓来源的MO/X，导致转分化为巨噬细胞，巨噬细胞进入中枢神经系统，并进一步分化为具有增强吞噬能力的小胶质细胞。我们的长期目标是将这种联合治疗方法转移到轻中度AD患者的I期人体试验中。

DESCRIPTION (provided by applicant): Human umbilical cord blood cells (HUCBC) are well known specific immunomodutators that confer a balanced (i.e. without complete immunosuppression, GVHD, or rejection) alteration of both peripheral and central immune responses. Other investigators have demonstrated they promote mobilization of adult bone marrow (BM) progenitor cells. In addition we recently demonstrated sera derived from HUCBC-infused PSAPP mice significantly inhibited microglial CD40 expression induced by IFN-? and markedly increased microglial A¿ phagocytic activity without unacceptable immune compromise. In confirmation, this effect was inhibited by the ligation of CD40 with CD40L protein. Importantly, primary adult microglia from these HUCBC-infused mice also showed increased A¿ phagocytic activity, and a strong A¿ IgG titer. Together these data suggest a balanced alteration of both innate and humoral immune microenvironments mediated by an HUCBC induced suppression of CD40 signaling and enhancement of A¿ IgG production. In accord with this downregulation of neurotoxic innate responses and upregulation of salutary humoral responses, A¿ levels/¿- amyloid deposits and cerebral amyloid angiopathy (CAA; an inflammatory response to vascular amyloid deposits) are reduced by HUCBC infusion in vivo, with attendant: (a) increased serum levels of A¿1-40, 42, suggesting efflux from the CNS (b) decreased soluble CD40L serum levels, (c) decreased microglial CD40 expression, and finally, (d) elevated CNS/serum levels of anti-inflammatory (IL-10 and TGF-21) with decrease pro-inflammatory cytokines (IL-1¿ and TNF-a). Finally, our preliminary data suggests that, compared with control primary BM derived monocytes/macrophages (MO/X), MO/X from HUCBC-infused PSAPP mice show enhanced A¿ phagocytic activity. These data along with our previous findings that crossing Tg2576 mice with CD40L null mice or treating PSAPP mice with CD40L antibody reduced A¿ loads, lead us to hypothesize that HUCBC infusion confers a mitigation of A¿/¿-amyloid pathology in Alzheimer's disease (AD) mice by alterations in innate and humoral immunity mediated by CD40-CD40L disruption resulting in mobilization of BM-derived progenitor MO/X, increased anti-inflammatory cytokine production, and increased amyloid clearance from the brain. Here we propose to test the hypothesis that HUCBC mediated dampening of the CD40-CD40L interaction reduces amyloidosis by investigating CD40 signaling in HUCBC infused PSAPP mice. Based on our preliminary data, we additionally plan to reconstitute the effects of HUCBC infusion by administering IL- 10, TGF-¿1 and NGF-¿ alone and in combinations; key factors we found to be essential for HUCBC ability to modulate CD40 activity and amyloidosis without systemic immunosuppression, rejection, or GVHD. Also, we will test the hypothesis that HUCBC infusion mobilizes BM-derived MO/X, leading to transdifferentiation into macrophages which enter the CNS and further differentiate into microglia with enhanced A¿ phagocytic capacity. It is our long-term goal to move this combination treatment into phase I human trials for patients with mild to moderate AD.