Integrative approaches defining the ontogeny, maintenance, and immune response dynamics of marginal-zone B cells

项目摘要 在战略上定位为循环和免疫系统之间的守门人，脾边缘 带(MZ)B细胞形成对抗血液传播病原体的前线。他们调解早期的保护 对不同的T依赖和T非依赖抗原的反应，通过采用模糊 先天免疫和获得性免疫之间的界限。在人类中，MZ B细胞缺陷与IgM降低有关 与包膜细菌感染相关的滴度和对败血症和死亡率的高易感性。在……里面 此外，它们的功能和定位受损与几种自身免疫病理有关。 尽管它们很重要，但MZ B细胞的个体发育和动态平衡的许多方面仍然不清楚。 MZ B细胞在其脾脏壁龛中的建立和维持由一组复杂的 调节细胞分裂、新的骨髓(BM)来源细胞的涌入、死亡及以后的规则 差异化。我们假设，支配MZ B细胞动力学的规则随着我们年龄的增长而演变，并且 在免疫原性相遇期间显著调节，导致它们的生态位大小发生深刻变化 和克隆性成分。在这里，我们提出了一种独特的综合方法，它综合了数学和 定量绘制MZ B细胞发育轨迹的实验策略和解剖 在整个生命周期内保持其数量和克隆多样性的机制。 具体地说，我们将开发机械数学模型来描述从经过验证的 在实验系统中，人们可以跟踪MZ B细胞室内的结构性替换， 在健康小鼠身上的长时间尺度上。这种方法将使我们能够衡量营业额，揭示任何 MZ B细胞库内的异质性，并确定它们的发育轨迹。此外，我们将采用 并扩展了这些确定性模型，以确定控制MZ B细胞生态位建立的规则 并将其描述为PDE系统，以量化细胞持续能力的动态转变， 作为它们进入隔间后的时间函数。接下来，我们将开发一种动态建模策略 使用表达An的新小鼠品系，绘制免疫反应期间B细胞分化途径的图谱 Notch2的抗原诱导报告基因和B细胞特异性突变。最后，我们将聘请一名 研究活化B细胞单细胞免疫谱系和转录图谱的计算流水线 并在免疫反应过程中抗原特异性克隆的多样性时生成系统发育树。

Project Summary Strategically positioned as the gatekeepers between the circulation and the immune system, splenic marginal zone (MZ) B cells form a frontline of defense against blood-borne pathogens. They mediate early protective responses against diverse T-dependent and T-independent antigens, by employing strategies that blur the boundary between innate and adaptive immunity. In humans, MZ B cell deficiency is linked to reduced IgM titers and heightened susceptibility to sepsis and mortality related to encapsulated bacterial infections. In addition, impairment in their function and localization is associated with several autoimmune pathologies. Despite their importance, many aspects of the ontogeny and homeostasis of MZ B cells remain obscure. The establishment and maintenance of MZ B cells in their splenic niche are determined by a complex set of rules that regulate cell division, the influx of new bone marrow (BM) derived cells, death, and onward differentiation. We hypothesize that the rules governing MZ B cell dynamics evolve as we age, and are modulated significantly during immunogenic encounters, resulting in a profound variation in their niche size and clonal composition. Here, we propose a unique integrative approach that synthesizes mathematical and experimental strategies to quantitatively map the developmental trajectories of MZ B cells and dissect the mechanisms that maintain their numbers and clonal diversity, across the lifespan. Specifically, we will develop mechanistic mathematical models to describe the data derived from a validated experimental system in which one can track the constitutive replacement within the MZ B cell compartment, over long timescales in healthy mice. This approach will allow us to measure turnover, reveal any heterogeneity within the MZ B cell pool, and define their developmental trajectories. Further, we will adopt and extend these deterministic models to identify the rules governing the establishment of MZ B cell niche in early life and formulate them as PDE systems to quantify the dynamic transitions in cells’ ability to persist, as a function of time since their compartmental entry. Next, we will develop a dynamical modeling strategy to map B cell differentiation pathways during immune responses, using novel mouse strains expressing an antigen-inducible reporter gene and B cell-specific mutations in Notch2. Lastly, we will employ a computational pipeline to study the single-cell immune repertoire and transcriptomic profiles of activated B cells and to generate phylogenetic trees of antigen-specific clones as they diversify during immune responses.