Role of natural immunity to self apoptotic exosomes in maintaining immune homeostasis

背景免疫系统将自我和非我区分开来，从而保护身体免受外来生物的伤害。为了确保自身的动态平衡，多种机制严密地调节免疫系统，避免自身免疫性疾病。与健康的免疫系统需要绝对避免自我反应性淋巴细胞克隆的经典理论相反，已知的先天类B细胞具有一定程度的自我反应性，并产生天然抗体。一组重要的天然抗体是针对由凋亡细胞表达的凋亡抗原(NapoAbbs)的。提示这些NapoAbb可能在促进有效的非炎症性清除凋亡细胞方面发挥作用，这对维持免疫平衡具有重要意义。然而，调控NapoAbbs产生的机制在很大程度上仍未被探索。我们小组首次描述了一种新的结构，使人联想到由凋亡的内皮细胞在Caspase-3激活的下游释放的外切体。这些凋亡外切体(ApoExo)与经典的凋亡小体有很大的不同。我们的观察表明，B1细胞对包装在ApoExo中的自身抗原的记忆可以在正常的免疫谱系中发现，并且ApoExo的输注可以触发针对凋亡抗原的特异性IgM和Ig G抗体的产生。假设我们假设，新发现的泡状结构的凋亡外切体刺激存在于正常免疫谱系中的特定B细胞，以分泌在非炎症性清除凋亡细胞中起重要作用的自然凋亡抗原自身抗体。我们还假设炎症信号可以调节这些过程。我们的长期目标是描述凋亡外切体在基本免疫过程中的功能，在维持内稳方面具有重要意义。在本研究计划中，我们建议：目标1：描述自然产生的凋亡外切体特异性B细胞(ApoExo)及其自身抗体分泌特征特征目标2：评估ApoExo衍生的Ig调节凋亡细胞非炎症清除的能力目标3：评估炎症环境如何调节ApoExo免疫反应科学方法本研究计划，围绕一系列结构良好的互补描述性和机械性目标，建议使用一系列可用于分析的广泛工具。这些包括大量的转基因小鼠品系和最先进的技术来表征和分离外切体、免疫细胞亚群和抗体。重要的是，PI和他的合作者团队在外体和免疫学方法方面拥有丰富的经验。影响这项研究计划完成后，将提供关于ApoExo对免疫动态平衡的贡献的巨大洞察力。据我们所知，这个节目是第一个研究这一吸引人的方向的节目。

BACKGROUND The immune system distinguishes the self from the non-self, allowing protection against foreign organisms from damaging the body. To ensure of its homeostasis, multiple mechanisms tightly regulate the immune system to avoid autoimmune disease. In contrast to the classical theory that a healthy immune system requires an absolute avoidance of self-reactive lymphocyte clones, the repertoires of innate-like B cells are known to incorporate some level of autoreactivity, and to produce natural antibodies. A significant set of natural antibodies are specific to apoptotic Antigens (NapoAbs) expressed by apoptotic cells. It is suggested that these NapoAbs may play a role in facilitating effective non-inflammatory clearance of apoptotic cells of importance in maintaining immune homeostasis. However, of the mechanisms that regulate the production of NapoAbs is still largely unexplored. Our group was the first to characterize a novel structure reminiscent of exosomes that are released downstream of Caspase-3 activation by apoptotic endothelial cells. These Apoptotic Exosomes (ApoExo) are strikingly different from classical apoptotic bodies. Our observations suggest that B1 cell memory to autoantigens packaged in ApoExo can be found within the normal immune repertoire and that the infusion of ApoExo triggers the production of IgM and IgG Antibodies specific to Apoptotic antigens. HYPOTHESIS We HYPOTHESIZE that newly identified vesicular structures Apoptotic Exosomes stimulate specific B cells that exist in the normal immune repertoire to secrete Natural Apoptotic Antigens autoantibodies of importance in non-inflammatory clearance of apoptotic cells. We also hypothesize that inflammatory signals can regulate these processes. OUR LONG-TERM OBJECTIVE is to delineate the functions of Apoptotic Exosomes in basic immunological processes of importance in maintaining homeostasis AIMS In this research program we propose: AIM 1: To characterize the repertoire of naturally occurring B cells specific to Apoptotic Exosomes (ApoExo) and their autoantibody secretion signature AIM 2: To evaluate ApoExo derived Ig capacity to modulate Non-Inflammatory clearance of apoptotic cells AIM 3: To evaluate how inflammatory context modulates ApoExo immune responses SCIENTIFIC APPROACH This research program, articulated around a well-structured series of complementary descriptive and mechanistic aims, proposes to use an extensive array of `tools' available for our analyses. These includes substantial number of genetically modified mouse strain and state of the art techniques to characterize and isolate exosome, immune cells subsets and antibodies. Importantly, the PI and his team of collaborators have extensive experience with exosomes and immunological approaches. IMPACT This research program will provide, upon completion, great insight on ApoExo contribution to immune homeostasis. This program is, to our knowledge, the first to investigate this appealing direction.