Mouse and mathematical models for HIV-1 suppression through HSPC

 描述(由申请人提供)：我们假设存在与抗HIV基因标记的细胞重新繁殖的临界“阈值”，超过该阈值，免疫系统将成功地保护免受HIV感染，低于该阈值，HIV-1感染将导致免疫系统失效。具有里程碑意义的遗传和种群研究表明，CCR5Δ32个个体可以免受艾滋病毒-1感染，同时还有一个引人注目的案例研究，该研究展示了CCR5Δ32造血干细胞/祖细胞异基因移植的治愈作用，并导致了大量使用经改造以抑制CCR5表达的细胞进行的移植研究。然而，确定治愈或终生抑制HIV-1所需的移植后再繁殖的临界水平尚未得到解决。鉴于抗HIV-1基因工程细胞在临床研究中预期的基因标记水平较低，了解最低水平的基因工程细胞保护个体免受HIV-1感染并恢复正常免疫功能的再繁殖参数至关重要。在这个“阈值水平”建立和了解免疫参数对于确定移植的实验条件至关重要，这样基因工程细胞的再繁殖在治疗上是有效的，可以防止HIV-1杀死大多数未受保护的细胞。在人类身上验证上述假设是不可能的，在非人类灵长类动物中也是不切实际的，因此我们建议将我们对再繁殖和对HIV-1的保护的理解扩展到一个人性化的小动物模型系统。BLT小鼠系统是研究HSPC移植的理想系统，因为与其他人源化小鼠模型不同，移植的人HSPC在人类胸腺的背景下分化，允许正常的人类T细胞分化，并导致外周血和HIV-1复制的所有主要组织部位的T细胞(以及巨噬细胞和B细胞)的强大重建。我们最近在一个与人类移植高度相似的恒河猴移植模型中发表了数千个HSPC克隆在时间波和通过不同的谱系潜力进行再繁殖方面的贡献。像猿猴模型一样，我们证明了BLT小鼠的再繁殖是多克隆的。移植可以通过实验操作来模拟不同参数的抗HIV基因工程细胞的再繁殖。为了分析我们对T细胞的观察和测量，我们将建立数学模型来捕捉关键的生物过程。这样的模型不仅有助于确定移植的阈值水平，还将允许人们在不同的移植方案和实验条件下做出系统的预测。例如，可以直接研究基因治疗试剂和移植剂量的影响。此外，通过包括描述HIV-1感染动力学、病毒载量的已知方程， 抗病毒治疗的不同组合，以及生物体中艾滋病毒-1的灭绝和总清除的可能性也可以被探索。

 DESCRIPTION (provided by applicant): We hypothesize that there exists critical "threshold" levels of repopulation with anti-HIV gene-marked cells above which protection of the immune system from HIV will be successful, and below which, HIV-1 infection will lead to immune system failure. The landmark genetic and population studies showing protection from HIV- 1 in CCR5Δ32 individuals coupled with the remarkable case study demonstrating cure by allogeneic transplantation of CCR5Δ32 hematopoietic stem/progenitor cells (HSPC) has led to numerous transplantation studies using cells engineered to knockdown CCR5 expression. However, determining the critical levels of repopulation after transplant necessary to cure or provide life-long suppression of HIV-1 has not been addressed. Given the expected low levels of gene-marking by anti-HIV-1 gene engineered cells in clinical studies, it is critical to understand the parameters for repopulation at which a minimum level of gene engineered cells protect the individual from HIV-1 infection and restore normal immune function. Establishing and understanding the immune parameters at this "threshold level" is critical for determining experimental conditions for transplant such that repopulation with gene engineered cells is therapeutically effective in preventing HIV-1 from killing the majority of unprotected cells. Testing the above hypothesis is impossible in humans and impractical in non-human primates, so we propose to extend our understanding of repopulation and protection from HIV-1 to a humanized small animal model system. The BLT mouse system is ideal for studying HSPC transplant since unlike other humanized mouse models, the transplanted human HSPC differentiate in the context of a human thymus allowing normal human T-cell differentiation and resulting in robust reconstitution of T-cells (as well as macrophages and Bcells) in peripheral blood and in all the major tissue sites of HIV-1 replication. We recently published in a rhesus macaque transplant model highly analogous to human transplant that thousands of HSPC clones contribute in temporal waves and by diverse lineage potential to repopulation. Like the simian model, we show that repopulation in BLT mice is polyclonal. Transplant can be experimentally manipulated to model different parameters of repopulation with anti-HIV gene engineered cells. To analyze our observations and measurements of T-cells, we will develop mathematical models that capture the key biological processes. Such models will not only help define threshold levels of transplantation, but will also allow one to make systematic predictions under different transplant protocols and experimental conditions. For example, the effects of gene therapeutic reagent and transplantation dosage can be directly investigated. Moreover, by including known equations describing the kinetics of HIV-1 infection, viral loads, the influence of different combinations of antiviral therapies, and the probabilities of extinction and total HIV-1 clearance in organisms can also be explored.