Anti-polysaccharide antibody responses in humanized mice

描述(由申请人提供)：啮齿动物模型对阐明基本免疫机制的能力是毋庸置疑的。不幸的是，这些机制的某些方面可能是物种特有的。此外，许多人类感染病原体不能在啮齿动物宿主中建立生产性感染。这些因素使从这些实验动物获得的知识转化为预防、诊断和治疗人类疾病的更好方法变得更加复杂。可与人造血细胞持久异种的新型免疫缺陷小鼠的发展为上述问题提供了潜在的解决方案。我们利用小鼠的NOD/SCID/共同细胞因子受体g链基因敲除(NSG)品系和人脐血(UCB)CD34+造血干细胞(HSCs)创建了造血人化小鼠(HIS小鼠)。我们已经发现，这些小鼠在血液、脾和一定程度上在淋巴结中植入了人B淋巴细胞，可重复和稳定地植入。然而，这些小鼠的B细胞室的主要亚群表现出不成熟的表型。这些HIS小鼠感染了螺旋体细菌Hermsii，导致了感染过程和通过IgM反应的分解，这种反应在性质上相似，但不如 在受感染的人类和小鼠模型中观察到的那些。虽然小鼠对赫氏杆菌的保护性免疫反应是T细胞非依赖(TI)反应，但这种反应被细菌刺激的Toll样受体(TLRs)所增强。HIS小鼠也不能对纯化的多糖类抗原产生抗体反应，除非给予TLR配体作为佐剂。最后，HIS小鼠对T细胞依赖抗原产生抗体反应，但这些反应很弱，产生的主要同型是IgM。这些观察结果使我们假设，如上所述产生的HIS小鼠，由于其淋巴细胞室发育不完全，对各种病原体和抗原的反应失败或次优。我们推测，这部分是由于宿主产生的小鼠细胞因子对移植的造血细胞缺乏人细胞因子受体的有效交叉刺激。在这一应用中，我们建议通过产生表达人IL-7和人BLyS(BAFF)的NSG小鼠作为脐带血HSCs的接收者来检验这一假设。我们预测，这两种修饰都将使HIS小鼠拥有更成熟和多样化的B细胞隔间，能够对各种抗原和病原体产生强大的免疫反应。因此，我们预测，由此产生的HIS小鼠将成为制定人类疾病诊断和治疗战略的更好模型。

DESCRIPTION (provided by applicant): The power of rodent models for the elucidation of basic immunological mechanisms is unquestioned. Unfortunately, particular aspects these mechanisms may be species specific. In addition, many human infectious pathogens are incapable of establishing productive infections in rodent hosts. These factors complicate the translation of knowledge gained from such experimental animals to better approaches for the prevention, diagnosis and treatment of human diseases. The development of new strains of immunodeficient mice that can be durably xenografted with human hematopoietic cells provides a potential solution to the problems mentioned above. We have utilized the NOD/SCID/common cytokine receptor g chain knockout (NSG) strain of mice and human umbilical cord blood (UCB) CD34+ hematopoietic stem cells (HSCs) to create hematopoietically humanized mice (HISmice). We have found that these mice are reproducibly and stably engrafted with human B lymphocytes in the blood, spleen and to some extent in the lymph nodes. However, major subpopulations of the B cell compartment in these mice appear phenotypically immature. Infection of these HISmice with the spirochete bacteria Borrelia hermsii results in a course of infection and resolution via an IgM response that is qualitatively similar, but is not as robust as those observed in infected humans and mouse models. While the protective immune response to B. hermsii in mice is a T cell independent (TI) response, this response is augmented by bacterial stimulation of Toll-like receptors (TLRs). HISmice also failed to make an antibody response to purified polysaccharide antigens unless TLR ligands were given as an adjuvant. Finally, HISmice mount antibody responses to T cell dependent antigens, but these responses are weak and IgM is the predominant isotype produced. These observations lead us to hypothesize that HISmice generated as describe above, fail or respond sub optimally to a variety of pathogens and antigens due to incomplete development of their lymphocyte compartments. We hypothesize that this is due, in part, to lack of efficient cross stimulation of human cytokine receptors on engrafting hematopoietic cells by host-produced murine cytokines. In this application, we propose to test this hypothesis by generating human IL-7 and human BLyS (BAFF) expressing NSG mice for use as recipients for UCB HSCs. We predict that both of these modifications will yield HISmice with more mature and diverse B cell compartments capable of mounting robust immune responses to a variety of antigens and pathogens. As such, we predict that the resulting HISmice will serve as far better models for the development of strategies for the diagnosis and treatment of human disease.