Inflammation as determinant of clonal selection in MPN progression

背景我们对Bcr/Bcr阴性的骨髓增生性肿瘤机制的认识 (MPN)涉及靶向JAK 2、MPL或CALR的限制性MPN驱动突变的识别，以及靶向JAK 2、MPL或CALR的限制性MPN驱动突变的识别。 炎症微环境，其特征在于细胞因子的表达和分泌增加， 趋化因子然而，炎症对MPN进展的贡献尚未得到解决。同样地， 导致MPN中炎性微环境的原因尚未确定。有趣的是 最近观察到不确定潜能的克隆造血（CHIP）表现出累积突变 与衰老相关，强烈表明炎症在克隆选择和疾病进展中的作用。 初步结果。我们已经建立了一个慢性炎症的动物模型，其中Notch蛋白的缺失， BM内皮（Tie 2CreERRBPJKO小鼠）中的信号传导诱导微RNA miR-155的上调， 增加的NF-kB信号传导和促炎细胞因子导致8-12个月内的MPN样疾病。 重要的是，这种微环境炎症环境大大加速了造血细胞的扩增 含有JAK 2 V617 F或TET 2-/-突变。假说.我们提出了一个模型，其中：a）长时间暴露 JAK 2 V616 F或TET 2-/-造血细胞向慢性炎性BM小生境的转移将有利于克隆扩增， 获得额外的突变和选择侵袭性克隆，导致MPN进展为 B）miR-155的上调在产生骨髓纤维化或/和AML的恶性循环中起关键作用; “恶性”炎症驱动MPN进展。目标。为了验证这些假设，我们提出：（1） 确定造血细胞暴露于炎性BM小生境是否导致克隆选择， 在JAK 2 V617 F和TET 2-/-驱动的MPN的体内模型中的疾病进展;（2）为了定义功能性MPN， miR-155和NF-kB在促进MPN进展中的关系，以及（3）为了确定MPN的炎症反应， 人BM微环境中与MPN进展相关的特征。战略为此我们将 使用Tie 2CreERRBPJKO小鼠作为慢性炎症的遗传控制动物模型， JAK 2 V616 F或TET 2-/-模型。此外，kB-Ras-/-和miR 155-/-小鼠将用于 探讨miR-155和NF-kB在疾病进展中的作用。慢病毒-DNA条形码系统组合 将使用荧光蛋白来跟踪体内克隆进化。这一做法将得到以下方面的补充： 全外显子组测序以鉴定突变，并通过活体显微镜观察克隆相互作用 有明确的BM壁龛。最后，将测试新型抗miR-155治疗方法的功效， 将分析MPN BM标本，以确定与疾病进展相关的炎症特征。 本案无关我们认为，这项工作的完成将对理解和 管理MPN，为早期治疗干预提供了坚实的理论基础，以抑制慢性 炎症，从而防止MPN进展。

Background. Our current understanding of the mechanisms for Bcr/Abl-negative myeloprolifereative neoplasia (MPN) involves recognition of restricted MPN driver mutations targeting JAK2, MPL, or CALR, and of an inflammatory microenvironment, characterized by heightened expression and secretion of cytokines and chemokines. However, the contribution of inflammation to MPN progression has not been addressed. Similarly, the causes that lead to an inflammatory microenvironment in MPN have not been defined. Interestingly, the recent observation that clonal hematopoiesis of indeterminate potential (CHIP) exhibit accumulating mutations that correlate with aging, strongly suggests a role for inflammation in clonal selection and disease progression. Preliminary Results. We have generated an animal model of chronic inflammation in which loss of Notch signaling in the BM endothelium (Tie2CreERRBPJKO mice) induces upregulation of the microRNA miR-155, increased NF-kB signaling and pro-inflammatory cytokines resulting in a MPN-like disease within 8-12 months. Importantly, this microenvironmental inflammatory milieu greatly accelerates expansion of hematopoietic cells containing JAK2V617F or TET2-/- mutations. Hypothesis. We propose a model in which: a) prolonged exposure of JAK2V616F or TET2-/- hematopoietic cells to a chronic inflammatory BM niche will favor clonal expansion, acquisition of additional mutations and selection of aggressive clones leading to MPN progression into myelofibrosis or/and AML; b) upregulation of miR-155 plays a pivotal role in generating a vicious cycle of “malignant” inflammation driving MPN progression. Aims. To test these hypotheses we propose: (1) To determine whether exposure of hematopoietic cells to an inflammatory BM niche leads to clonal selection and disease progression in in vivo models of JAK2V617F and TET2-/- driven MPN; (2) To define the functional relationship between miR-155 and NF-kB in promoting MPN progression, and; (3) To identify an inflammatory signature in the human BM microenvironment correlating with MPN progression. Strategy. To this end, we will use Tie2CreERRBPJKO mice as a genetically-controlled animal model of chronic inflammation, in combination with JAK2V616F or TET2-/- models in transplant settings. In addition, kB-Ras-/- and miR155-/- mice will be used to address the role of miR-155 and NF-kB in disease progression. A lentiviral-DNA barcoding system combined with fluorescent proteins will be used to follow clonal evolution in vivo. This approach will be complemented by whole exome sequencing to identify mutations, and by intravital microscopy, to visualize clones interactions with defined BM niches. Finally, the efficacy of a novel anti-miR-155 therapeutic approach will be tested, and MPN BM specimens will be analyzed to identify inflammatory signatures correlating with disease progression. Relevance. We believe that accomplishment of this work will have impact on the understanding and management of MPN, providing a solid rationale for early therapeutic intervention to suppress chronic inflammation and thus, preventing MPN progression.