Cellular crosstalk in the hematopoietic microenvironment

摘要： 我们的总体目标是确定产生肿瘤坏死因子α的造血细胞调控的机制。 血管和血管周围HSPC(造血干/祖细胞)血管壁龛。HSPC是 负责生成血液中发现的所有细胞，这些细胞是生命所必需的。HSPC驻留在 骨髓与由不同类型的细胞组成的特定结构(壁龛)相关，包括 内皮细胞、CD45-CD31-Lepr+、CD45-CD31-NG2+细胞和巨核细胞。这些利基市场维持着 规范HSPC，是HSC维护不可缺少的。然而，人们对这种机制知之甚少。 在动态平衡和再生期间调节不同的生态位成分。确定这些 机制对于理解HSPC如何在健康和疾病中受到调控至关重要，因为它可能导致 到针对利基市场的治疗疾病的新疗法。 在我们的初步研究中，我们发现了两种全新的肿瘤坏死因子产生细胞功能。 造血学：1)我们发现骨髓(但不是外周血)粒细胞利用肿瘤坏死因子产生一种 促进维持造血的基质壁龛扩张的再生微环境 促进小鼠自体移植后的造血恢复。我们的结果表明 粒细胞和/或肿瘤坏死因子信号的操纵可用于加速供体细胞在 移植。我们还发现，在人类β地中海贫血患者中，较高数量的粒细胞 最初的移植物预示着外周和中性粒细胞植入的速度更快。这些数据支持这样一种假设： 粒细胞也可能在推动人类患者再生方面发挥作用。2)我们发现肿瘤坏死因子- 产生细胞控制血管周围壁龛的大小和HSC对骨髓壁龛的定位。我们的结果 证明在动态平衡期间，产生肿瘤坏死因子的细胞通过控制 壁龛内皮细胞和血管周围细胞的数量。我们还发现，在肿瘤坏死因子α-/-小鼠中， 远离血管周围的壁龛。在本提案中，我们研究了这种肿瘤坏死因子介导的机制。 蜂窝串扰。在目标1中，我们将研究粒细胞驱动血管和 造血再生，它们在血管内稳态中的作用，以及药物操作是否 这些粒细胞中的一部分可用于促进骨髓清除术后的再生。在本提案的目标2中，我们 将利用嵌合小鼠和遗传模型重新激活Tnfrsf1a(肿瘤坏死因子受体之一)和肿瘤坏死因子α HSC及其壁龛的缺失和5色免疫荧光成像以识别来源和靶点 调节肝星状细胞的功能和定位的肿瘤坏死因子。

Abstract: Our overall goal is to identify the mechanisms through which TNFα-producing hematopoietic cells regulate blood vessels and perivascular HSPC (Hematopoietic stem and progenitor cells) vascular niches. HSPC are responsible for generating all the cells found in the blood and are indispensable for life. HSPC reside in the bone marrow associated with specific structures (niches) composed by different types of cells including endothelial cells, CD45-CD31-LepR+, CD45-CD31-Ng2+ cells and megakaryocytes. These niches maintain and regulate HSPC and are indispensable for HSC maintenance. However, little is known about the mechanisms that regulate the different components of the niche during homeostasis and regeneration. Identifying these mechanisms is critical to understand how HSPC are regulated in health and disease and because it might lead to novel therapies that target the niche to treat disease. In our preliminary studies we have discovered two entirely novel functions for TNF-producing cells in hematopoiesis: 1) We found that bone marrow (but not peripheral) granulocytes use TNF to create a regenerative microenvironment that promotes the expansion of the stromal niches that sustain hematopoiesis and accelerates hematopoietic recovery after autologous transplantation in mice. Our results suggest that manipulation of granulocytes and/or TNF signals can be used to accelerate donor cell engraftment after transplantation. We also found, in human beta thalassemia patients, that higher numbers of granulocytes in the initial graft predicted faster peripheral and neutrophil engraftment. This data supports the hypothesis that granulocytes might also play a role in driving regeneration in human patients. 2) We found that TNF- producing cells control the size of the perivascular niche and HSC localization to BM niches. Our results demonstrate that, during homeostasis, TNF-producing cells regulate vascular niche abundance by controlling the numbers of endothelial cells and perivascular cells in the niche. We also found that, in Tnfα-/- mice, HSC relocate away from perivascular niches. In this proposal we investigate the mechanisms of this TNF-mediated cellular crosstalk. In Aim 1 we will investigate the mechanisms through which granulocytes drive vascular and hematopoietic regeneration, their function in vascular homeostasis, and whether pharmacological manipulation of these granulocytes can be utilized to promote regeneration after myeloablation. In Aim 2 of this proposal we will utilize chimeric mice and genetic models for Tnfrsf1a (one of the TNF receptors) reactivation and Tnfα deletion and a 5-color immunofluorescence imaging of HSC and their niches to identify the source and targets of TNF that regulate HSC function and localization to the niche.