Epigenetic downregulation of the antibody response and inhibition of autoimmunity

描述（由申请人提供）：抗体反应的表观遗传下调和自身免疫的抑制表观遗传标记（包括组蛋白修饰、DNA甲基化和microrna）与遗传程序“相互作用”来调节B细胞功能，如类开关DNA重组（CSR）、体细胞超突变（SHM）和浆细胞分化，从而通知抗体反应。表观遗传失调可导致异常的抗体反应和介导自身免疫的复合遗传易感性，包括系统性狼疮（SLE），在这种情况下，大量浆细胞分泌的针对核抗原的自身抗体（主要是IgG）发生严重突变和类别转换，产生广泛的组织和器官损伤。根据我们在体外人类和小鼠B细胞以及正常和狼疮易感小鼠中令人满意的初步发现，我们假设表观遗传调节剂组蛋白去乙酰化酶抑制剂（hdi）抑制CSR/SHM，浆细胞分化，从而抑制特异性抗体和自身抗体反应，并阻止自身免疫和“治愈”狼疮晚期小鼠。我们还认为hdi通过增强宿主microRNA基因的乙酰化和转录来上调选定microRNA的表达，从而抑制抗体和自身抗体反应。根据我们的初步数据，我们认为hdd上调miR-155， miR-181b， miR-93以下调AID （CSR/SHM的核心），miR- 146a下调转录因子Irf5和（通过Stat1） T-bet（对IgG2a和狼疮的CSR很重要），miR-127和miR-125b下调Blimp1/Xbp1（对浆细胞分化至关重要）。由于过去25年来在B细胞生物学、分子CSR/SHM和自身免疫方面取得的成就，以及最近建立的尖端表观遗传学方法，Casali实验室在测试这些新假设方面处于独特的地位。我们将分析hdi（丙戊酸、丁酸、亚甲基苯胺羟肟酸）对正常C57BL/6和Balb/c小鼠t依赖性和t非依赖性抗体反应的影响，以及对狼疮易感小鼠MRL/Faslpr/lpr和B6.NZM/Sle1.Sle2自身抗体反应和自身免疫的影响。Sle3小鼠（Aim 1）。我们将通过（hdi）介导的miR-155、miR-181b、miR-93、miR-146a、miR-127和miR-125b的上调，通过增强这些microRNA“宿主基因”的乙酰化，来解决AID、Irf5、T-bet、Blimp1和Xbp1的下调问题（Aim 2）。最后，我们将利用AID+ B细胞中缺乏Dicer或Drosha或aida和Prdm1 mRNA中缺乏microRNA靶向位点的狼疮易感小鼠，确定microRNA在介导HDI抑制自身免疫中的作用，并鉴定狼疮小鼠全基因组HDI易感microRNA/靶mRNA对（Aim 3）。我们的研究具有重要的创新意义，因为它解决了狼疮的核心表观遗传机制，并将在表观遗传学，免疫调节和自身免疫领域产生持续的影响。最后，它是精巧的转化，因为（在昂贵的生物制剂进入临床试验的时候）它为使用廉价和可用的表观遗传调节剂作为自身免疫性疾病的治疗方法提供了一个健全的机制基础。！

DESCRIPTION (provided by applicant): Epigenetic downregulation of the antibody response and inhibition of autoimmunity Epigenetic marks (including histone modifications, DNA methylation and microRNAs) "interact" with genetic programs to regulate B cell functions, such as class switch DNA recombination (CSR), somatic hypermutation (SHM) and plasma cell differentiation, thereby informing the antibody response. Epigenetic dysregulation can result in aberrant antibody responses, and compound genetic susceptibility to mediate autoimmunity, including systemic lupus (SLE), in which heavily mutated and class-switched (mainly IgG) autoantibodies to nuclear antigens, as secreted by large numbers of plasma cells, produce widespread tissue and organ injury. Prompted by our compelling preliminary findings in human and mouse B cells in vitro, and in normal and lupus-prone mice, we hypothesize that the epigenetic modulators histone deacetylase inhibitors (HDIs) inhibit CSR/SHM, plasma cell differentiation and, therefore, specific antibody and autoantibody responses, and prevent autoimmunity and "cure" mice in an advanced stage of lupus. We also argue that HDIs inhibit antibody and autoantibody responses by upregulating expression of selected microRNAs through enhanced acetylation and transcription of those microRNA host genes. As suggested by our preliminary data, we contend that HDIs upregulate miR-155, miR-181b, miR-93 to downregulate AID (central to CSR/SHM), miR- 146a to downregulate transcription factors Irf5 and (through Stat1) T-bet (important in CSR to IgG2a and lupus), miR-127 and miR-125b to downregulate Blimp1/Xbp1 (critical for plasma cell differentiation). The Casali lab is uniquely poised to test these novel hypotheses, owing to its record of accomplishment in B cell biology, molecular CSR/SHM and autoimmunity over the last 25 years, and the recently established cutting-edge epigenetic approaches. We will analyze the impact of HDIs (valproic acid, butyrate, suberoylanilide hydroxamic acid) on T-dependent and T-independent antibody responses in normal C57BL/6 and Balb/c mice, and autoantibody responses and autoimmunity in lupus-prone MRL/Faslpr/lpr and B6.NZM/Sle1.Sle2.Sle3 mice (Aim 1). We will address the downregulation of AID, Irf5, T-bet, Blimp1 and Xbp1, as targeted by (HDI-mediated) upregulation of miR-155, miR-181b, miR-93, miR-146a, miR-127 and miR-125b through enhanced acetylation of these microRNA "host genes" (Aim 2). Finally, we will define the role of microRNAs in mediating HDI inhibition of autoimmunity using lupus-prone mice lacking Dicer or Drosha in AID+ B cells or lacking microRNA targeting sites in Aicda and Prdm1 mRNAs, and identify genome-wide HDI-susceptible microRNA/target mRNA pairs in lupus mice (Aim 3). Our proposal is highly significant and innovative, as it addresses core epigenetic mechanisms of lupus and will have sustained impact on the fields of epigenetics, immunoregulation and autoimmunity. Finally, it is exquisitely translational, as (at the time when expensive biologics enter clinical trials) it provies a sound mechanistic basis for use of inexpensive and available epigenetic modulators as therapeutics in autoimmune diseases. !