B-lymphocyte Targeting Therapies for Autoimmune Diabetes

描述（由申请人提供）：虽然1型糖尿病（T1 D）最终由自身反应性T细胞介导，但在NOD小鼠中，也可能在人类中，B淋巴细胞发挥额外的关键致病作用。通过免疫球蛋白（IG）介导的捕获摄取胰腺β细胞蛋白的能力，B淋巴细胞似乎充当最有效地支持致糖尿病CD 4 T细胞扩增的抗原呈递细胞（APC）亚群。最近的临床试验结果表明，用CD 20特异性利妥昔单抗抗体短暂消耗B淋巴细胞并不能长期减弱致糖尿病性自身免疫。我们最近发现用利妥昔单抗样CD 20特异性抗体治疗不能有效预防 当在NOD小鼠中启动时，T1 D发展已经表现出建立的高水平致病性自身免疫的迹象，类似于目前用于识别未来高疾病风险的人类。这似乎是由于进入NOD小鼠胰岛的B淋巴细胞变成CD 20阴性。此外，利妥昔单抗未能耗尽边缘区（MZ）亚组的成熟B淋巴细胞，可以发挥有效的APC活性。我们还发现NOD小鼠的腹膜CD 20阴性B1 B淋巴细胞隔室中富含致糖尿病克隆型。这些问题使人们对利妥昔单抗可用作单一治疗T1 D干预方法的程度产生疑问。因此，本提案的总体目标是确定可能独立或与利妥昔单抗联合提供改进的B淋巴细胞定向T1 D干预方法的策略。目的1将解决在何种程度上做致糖尿病B淋巴细胞驻留在隔室折射抗CD 20介导的删除。通过使用抑制BAFF/APRIL存活因子的药物而不是抗CD 20，可以潜在地删除更广泛的B淋巴细胞群体，包括NOD胰岛中的那些。也有报道称，在NOD小鼠中，B淋巴细胞介导致糖尿病性T细胞扩增的能力超过了其他APC亚型支持疾病保护性调节性T细胞（Treg）应答的能力。FDA批准的试剂GCSF（Neulasta）可以增强具有支持Treg活性的能力的骨髓树突状细胞的募集。因此，目的2将评价BAFF/APRIL抑制而非抗CD 20是否为NOD小鼠中B淋巴细胞定向的晚期T1 D预防提供了更好的手段，或者与GCSF的共治疗是否协同增强了任一方法的功效。其他初步研究表明，第4号染色体上名为Idd 9/11的T1 D易感基因座内的一个目前未知的基因通过损害通常抑制自身反应性B淋巴细胞反应的免疫调节途径，导致NOD小鼠的疾病发病机制。我们有证据表明，这种途径可能在其他操作点被一些人类T1 D易感基因破坏。目的3是确定在NOD小鼠中鉴定出的贡献性Idd 9/11区基因是否可以揭示免疫调节途径，也可能调节人类中的致糖尿病B淋巴细胞发育，这可能适合于药理学靶向。

DESCRIPTION (provided by applicant): While type 1 diabetes (T1D) is ultimately mediated by autoreactive T-cells, in NOD mice, and also likely in humans, B-lymphocytes play an additional key pathogenic role. Through an ability to take up pancreatic ss cell proteins by immunoglobulin (Ig) mediated capture, B-lymphocytes appear to serve as an antigen presenting cell (APC) subset that most efficiently supports expansion of diabetogenic CD4 T-cells. Results from a recent clinical trial indicated transient depletion of B-lymphocytes with the CD20 specific rituximab antibody did not provide for long-term attenuation of diabetogenic autoimmunity. We recently found treatment with a rituximab- like CD20 specific antibody fails to efficiently prevent T1D development when initiated in NOD mice already manifesting signs of established high levels of pathogenic autoimmunity similar to that currently used to identify humans at high future disease risk. This appears to result from B-lymphocytes entering the pancreatic islets of NOD mice becoming CD20 negative. Furthermore, rituximab fails to deplete the marginal zone (MZ) subset of mature B-lymphocytes that can exert potent APC activity. We have also found diabetogenic clonotypes are enriched in the peritoneal CD20 negative B1 B-lymphocyte compartment of NOD mice. These issues call into question the extent that rituximab could be used as a mono-therapeutic T1D intervention approach. Thus, the overall goal of this proposal is to identify strategies that might independently, or in conjunction with rituximab, provide an improved B-lymphocyte directed T1D intervention approach. Aim 1 will address to what extent do diabetogenic B-lymphocytes reside in compartments refractive to anti-CD20 mediated deletion. A broader array of B-lymphocyte populations, including those in NOD islets, can potentially be deleted through use of agents inhibiting the BAFF/APRIL survival factors rather than anti-CD20. It has also been reported that in NOD mice the ability of B-lymphocytes to mediate expansion of diabetogenic T cells outpaces the capacity of other APC subtypes to support disease protective regulatory T-cell (Treg) responses. The FDA approved reagent GCSF (Neulasta) can enhance recruitment of myeloid dendritic cells with a capacity to support Treg activity. Hence, Aim 2 will evaluate whether BAFF/APRIL inhibition, rather than anti-CD20, provides a better means for B-lymphocyte directed late-stage T1D prevention in NOD mice, or if co-treatment with GCSF synergistically enhances the efficacy of either approach. Other preliminary studies indicate a currently unknown gene(s) within a T1D susceptibility locus designated Idd9/11 on Chromosome 4 contributes to disease pathogenesis in NOD mice by impairing an immunoregulatory pathway normally inhibiting autoreactive B-lymphocyte responses. We have evidence this pathway may be disrupted at other operational points by some human T1D susceptibility genes. Aim 3 is to determine if identification of a contributory Idd9/11 region gene(s) in NOD mice may reveal an immunoregulatory pathway, also potentially regulating diabetogenic B- lymphocyte development in humans, that may be amenable to pharmacological targeting.