New perspective on innate antibodies in mice

描述(申请人提供)：目前对细菌刺激的先天免疫反应的概念，如脂多糖(例如，这里使用的来自鼠伤寒沙门氏菌的脂多糖)，主要基于体外刺激来自未受刺激的小鼠的脾细胞的数据。然而，我们最近在活体小鼠模型中对内毒素刺激的发现表明，这些体外数据中的大部分不适合对体内必然发生的先天性反应进行建模。同样，我们的发现也提出了一个问题，即如何将体内模型(B细胞转基因、TLR缺陷、寄生虫感染等)的数据联系起来。对正常(基因完整)动物的内毒素反应。具体地说，我们发现体内大多数内毒素刺激的浆细胞反应是由B-1a(CD5+B-1)细胞产生的，其中大部分只在注射内毒素后才迁移到脾内。此外，我们发现体内对内毒素的即时反应是由B-1a细胞产生的，这些B-1a细胞驻留在脾中，令人惊讶地在1-2天内分化为浆细胞，而不进行细胞分裂。这种浆细胞分化的最初波在整体体内反应中所占的比例相对较小，在体内反应在第3天达到峰值，主要是由移居的B-1a细胞在分化为浆细胞之前(或同时)分裂产生的。然而，早期反应者的快速反应能力--可以比作原始免疫记忆--可能是利用先天免疫系统“填补缺口”直到适应性免疫系统接管的能力的关键。这里提出的研究旨在提供一个清晰的观点，B细胞和参与对入侵病原体的天然抗体反应的机制，包括但不限于内毒素。到目前为止，我们的发现表明，我们可以有效地利用介导这些反应的微小功能B细胞亚群(来自未刺激或脂多糖刺激的小鼠的脾细胞的0.1-3%)。因此，我们现在建议进一步定义区别居留B-1细胞和移民B-1细胞反应的细胞、解剖学和分子机制，并确定其他B细胞间隔和受体相互作用对固有反应的贡献程度。总之，这些研究将为开发复杂的天然免疫机制提供基础，这些机制涉及自然抗体反应，必须迅速产生，以将入侵病原体造成的损害降至最低。公共卫生相关性：这里提出的研究旨在为B细胞和参与对入侵病原体的天然抗体反应的机制提供一个清晰的观点。到目前为止，我们的发现表明，我们可以有效地与介导这些反应的微小功能B细胞亚群合作。这些研究将为开发复杂的天然免疫机制提供基础，天然抗体反应必须迅速产生，以将入侵病原体造成的损害降至最低。

DESCRIPTION (provided by applicant): Current concepts of innate immune responses to bacterial stimuli such as lipopolysaccharides (e.g., the LPS from S. typhimurium used here) are largely based on data from in vitro stimulation of spleen cells taken from unstimulated mice. However, our recent findings with LPS stimulation in an in vivo mouse model demonstrate that much of this in vitro data is not suitable for modeling innate responses, which occur perforce in vivo. Similarly, our findings raise questions about the how to relate data from in vivo models (B-cell transgenic, TLR- deficient, parasite infection, etc.) to LPS responses in normal (genetically intact) animals. Specifically, we find that the majority of the LPS-stimulated plasma cell response in vivo is produced by B-1a (CD5+ B-1) cells, most of which only migrate into the spleen after LPS injected. Further, we find that the immediate response to LPS in vivo is produced by the B-1a cells that are resident in the spleen and surprisingly differentiate into plasma cells within 1-2 days without undergoing cell division. This initial wave of plasma cell differentiation accounts for a relatively small proportion of the overall in vivo response, which peaks at day 3 and is largely produced by immigrant B-1a cells that divide before (or while) differentiating to plasma cells. However, the rapid response capabilities of the early responders, which can be likened to primitive immunologic memory, may be key to the ability to use the innate immune system to "fill in the gap" until the adaptive immune system can take over. Studies proposed here are designed to provide a clear view of the B cells and mechanisms that participate in innate antibody responses to invading pathogens, including but not restricted to LPS. Our findings to date demonstrate that we can work effectively with the tiny functional B cell subsets that mediate these responses (0.1-3% of spleen cells from unstimulated or LPS-stimulated mice, respectively). Thus, we now propose to further define the cellular, anatomical and molecular mechanisms that distinguish resident B-1 responses from those of immigrant B-1 cells, and to determine the extent to which other B cell compartments and receptor interactions contribute to the innate response. Together, these studies will provide grounds for developing a comprehensive and informative model of the complex innate immunity mechanisms involved in natural antibody responses that must be produced rapidly to minimize damage due to invading pathogens. Public Health Relevance: Studies proposed here are designed to provide a clear view of the B cells and mechanisms that participate in innate antibody responses to invading pathogens. Our findings to date demonstrate that we can work effectively with the tiny functional B cell subsets that mediate these responses. These studies will provide grounds for developing a comprehensive and informative model of the complex innate immunity mechanisms involved in natural antibody responses that must be produced rapidly to minimize damage due to invading pathogens.