Epigenetic downregulation of the antibody and autoantibody response

描述(由申请人提供)：抗体和自身抗体反应的表观遗传下调标记包括DNA甲基化、组蛋白修饰和microRNAs。正如我们所争论的那样，这些基因与调节B细胞功能的遗传程序相互作用，如类开关DNA重组(CSR)、体细胞高突变(SHM)和浆细胞分化，从而通知抗体反应。表观遗传失调可导致狼疮对外源性抗原(如病毒和细菌上的抗原)或自身抗原(如染色质、组蛋白和dsDNA)的异常抗体反应。我们假设，表观遗传调节剂组蛋白脱乙酰酶(HDAC)抑制物(HDI)抑制B细胞固有功能CSR/SHM和浆细胞分化，从而钝化抗体和自身抗体反应。我们进一步认为，HDI通过上调选定的microRNAs来抑制这些B细胞的功能，包括miR-155、miR-181b和miR-361下调AID(Aicda基因，对CSR/SHM至关重要)，以及miR-23b、miR-30a和miR-125下调Blimp1(Prdm1基因，对浆细胞分化至关重要)。我们的假设主要集中在B细胞上，并得到了我们令人信服的数据的支持，这些数据使用了体外纯化的人和小鼠B细胞，以及在正常小鼠中对T依赖和T非依赖抗原的反应，以及通过HDI预防和治疗狼疮易感小鼠的疾病。我们在B细胞生物学、分子CSR/SHM机制和自身免疫方面的优势，以及我们尖端的表观遗传工具和方法，使我们能够独一无二地准备检验我们的假设。我们将：(1)分析HDIs(丙戊酸、丁酸盐和SAHA)对CSR/SHM和浆细胞分化的影响，以及对正常C57BL/6和Balb/c小鼠特异性T依赖和T非依赖性抗体应答的影响，以及对易狼疮MRL/Faslpr/LPR和B6.NZM/Sle1.Sle2.Sle3小鼠自身抗体应答的影响；(目的2)利用分子生物学、生物化学和高通量/生物信息学工具，分析HDI通过增强组蛋白乙酰化和microRNA“宿主基因”转录而上调B细胞miR-155、miR-181b、miR-361、miR-23b、miR-30a和miR-125b，解决这些microRNAs下调AID和Blimp1的问题，并使用AGO HITS-CLIP构建Aicda和Prdm13‘UTRs的体内靶向图谱；(目的3)通过三管齐下的体内综合方法证实B细胞microRNAs在介导HDI抗体和自身抗体反应中的关键作用，包括构建新的在Aicda或Prdm1 3‘UTR中缺乏特异性microRNA靶点的敲打小鼠，B细胞条件性Dird或DROSHA KO小鼠，以及在B细胞中表达针对miR-155、miR-181b和miR-361(针对Aicda)和/或针对miR-23b、miR-30a和miR-125b(针对Prdm1)的“海绵”抑制剂的小鼠。我们的建议具有很高的创新性和精妙的翻译能力。它将提供表观遗传学和免疫调节方面的机械性见解和未来方向，包括B细胞microRNAs在抗体/自身抗体反应中的关键作用以及作为自身免疫新疗法的表观遗传学工具。

DESCRIPTION (provided by applicant): Epigenetic downregulation of the antibody and autoantibody response Epigenetic marks include DNA methylation, histone modifications and microRNAs. As we have contended, these "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 to exogenous antigens, such as those on viruses and bacteria, or self-antigens, such as chromatin, histones and dsDNA in lupus. We hypothesize that the epigenetic modulators histone deacetylase (HDAC) inhibitors (HDIs) inhibit the B cell intrinsic functions CSR/SHM and plasma cell differentiation, thereby blunting antibody and autoantibody responses. We further argue that HDIs inhibit these B cell functions by upregulating selected microRNAs, including miR-155, miR-181b and miR-361 to downregulate AID (Aicda gene, critical for CSR/SHM), as well as miR-23b, miR-30a and miR-125 to downregulate Blimp1 (Prdm1 gene, critical for plasma cell differentiation). Our hypotheses uniquely focus on B cells and are supported by our compelling data using purified human and mouse B cells in vitro, and in vivo in normal mice responding to T-dependent and T- independent antigens, and prevention of disease and "treatment" of lupus-prone mice by HDI. Our strengths in B cell biology, molecular CSR/SHM mechanisms and autoimmunity, and our cutting-edge epigenetic tools and approaches make us uniquely poised to test our hypotheses. We will: (Aim 1) analyze the impact of HDIs (valproic acid, butyrate and SAHA) on CSR/SHM and plasma cell differentiation, and on specific T-dependent and T-independent antibody responses in normal C57BL/6 and Balb/c mice and autoantibody responses in lupus-prone MRL/Faslpr/lpr and B6.NZM/Sle1.Sle2.Sle3 mice; (Aim 2) use molecular biology, biochemistry and high-throughput/bioinformatics tools to analyze HDI-mediated upregulation of miR-155, miR-181b, miR-361, miR-23b, miR-30a and miR-125b in B cells through enhanced histone acetylation and transcription of the microRNA "host genes", address downregulation of AID and Blimp1 by these microRNAs, and construct microRNA in vivo targeting maps of Aicda and Prdm1 3'UTRs using Ago HITS-CLIP; (Aim 3) prove the critical role of B cell microRNAs in mediating HDI suppression of antibody and autoantibody responses using a three-prong integrated in vivo approach involving construction of new knockin mice lacking specific microRNA targeting sites in Aicda or Prdm1 3'UTR, B cell conditional Dicer or Drosha KO mice, and mice expressing "sponge" inhibitors specific for miR-155, miR-181b and miR-361 (targeting Aicda) and/or for miR-23b, miR-30a and miR-125b (targeting Prdm1) in B cells. Our proposal is highly innovative and exquisitely translational. It will provide mechanistic insights and future directions in epigenetics and immunoregulation, including the critical role of B cell microRNAs in antibody/autoantibody responses and epigenetic tools as new therapeutics in autoimmunity.