Role of Regulatory T-Lymphocytes in Chronic Heart Failure

 描述（由申请人提供）： 目前没有大规模的免疫调节临床治疗心力衰竭（HF）。迄今为止，治疗性免疫调节的主要焦点是中和炎症介质，如肿瘤坏死因子-α，不幸的是，这种方法在临床试验中失败了。最近，我们描述了全球免疫细胞网络的深刻重塑和迄今为止未被认识到的慢性缺血性HF中的不利的心脾轴，其促进了衰竭心脏中免疫细胞介导的组织损伤。这一新的发现表明，直接靶向HF中改变的特定白细胞群可能是治疗免疫调节的更好方法。调节性T细胞（TCFs）是表达叉头盒蛋白-3（Foxp 3）转录因子并以接触依赖性、抗原非特异性方式抑制免疫细胞应答的CD 4 + T淋巴细胞;其在慢性HF中的病理生理作用尚不清楚。在我们的初步研究中，我们意外地发现，在HF中，TGFs强烈地浸润衰竭的心脏，并且不是抗炎的，从而不是心脏保护的，而是矛盾地表现出促炎特征，并且作为疾病介质显著地起作用，赋予实质性的抗血管生成、促纤维化和促炎作用。基于这些数据，我们假设功能失调的TdR对于HF中的左心室（LV）重构、毛细血管稀疏、炎症和疾病进展是必不可少的， 是免疫调节的关键细胞靶点。三个目标将检验这一假设。在目标1中，我们将描述冠状动脉结扎和HF的C57 BL/6小鼠以及假手术对照中的Treg全球运输和Treg促炎信号传导的改变。在结扎后的一系列时间点，通过流式细胞术和免疫组织化学在心脏、血液、脾脏和纵隔淋巴结中确定TcB和其他T细胞亚群及其炎症特征，并将其与LV和脾脏重塑和炎症相关联。BrdU标记将指示体内Treg增殖。此外，使用人类HF生物样本库，我们将确定Tcl 3在人类衰竭心脏中的丰度和分布，并分析患有HF（射血分数降低）的非卧床患者与匹配的非衰竭对照的循环Tcl 3（和其他T细胞）。在目的2中，我们将通过选择性地（可逆地）消耗患有慢性HF的Foxp 3-DTR Tg小鼠中的Tcl 4，然后评估对免疫细胞谱、炎症、循环和骨髓内皮祖细胞、体内血管生成和LV的影响，来确定Tcl 4在LV重塑和新血管形成中的作用。 重塑在平行研究中，将使用体外管形成测定法比较来自假手术小鼠、HF小鼠和具有THBE消融和随后重建的HF小鼠的脾THBE的相对抗血管生成作用。在目标3中，我们将确定功能障碍性TdR是否是慢性HF损伤性心脾轴的重要介质。将来自患有早期或晚期HF（对应于Treg功能障碍的不同阶段）的Foxp 3-DTR Tg小鼠的CD45.2单核脾细胞过继转移到CD45.1未处理小鼠中，在转移之前进行或不进行Treg消融。然后将在受体小鼠中测量细胞转移对LV/脾重塑、炎症和T细胞/免疫细胞谱的长期影响。同时，我们将评估HF和假手术小鼠的脾T细胞的能力， 体外抑制CD 4+和CD 8+脾T淋巴细胞的活化，以及通过使用来自TNFR 1-/-和TNFR 2-/- HF小鼠的脾T细胞的类似研究，TNFR信号传导在HF Treg功能障碍中的作用。通过最终确定TGFAP在病理性心脏重塑中的作用，这些研究将进一步加深我们对慢性缺血性HF中炎症激活的细胞基础的理解，并为最近发现的促炎症和组织损伤性心脾轴的基本基础提供创新的观点。此外，通过提供直接 尽管这些研究证明TdR在HF中作为抗血管生成和（矛盾的）促炎介质，但这些研究将确定细胞类型特异性而非TdR特异性免疫调节的新靶点。

 DESCRIPTION (provided by applicant): No large-scale immunomodulatory clinical therapies currently exist for heart failure (HF). To date, the primary focus of therapeutic immunomodulation has been to neutralize inflammatory mediators such as tumor necrosis factor-α, an approach that unfortunately failed in clinical trial. Recently, we described profound remodeling of the global immune cell network and a heretofore-unappreciated adverse cardiosplenic axis in chronic ischemic HF that promotes immune cell-mediated tissue injury in the failing heart. This novel discovery suggests that directly targeting specific leukocyte populations that are altered in HF may represent a better approach to therapeutic immunomodulation. Regulatory T-cells (Tregs) are CD4+ T-lymphocytes that express the forkhead box protein-3 (Foxp3) transcription factor and suppress immune cell responses in a contactdependent, antigen nonspecific manner; their pathophysiological role in chronic HF is unknown. In our preliminary studies, we have unexpectedly discovered that in HF, Tregs robustly infiltrate the failing heart, and rather than being anti-inflammatory and thereby cardioprotective, paradoxically exhibit pro-inflammatory features and function prominently as disease mediators, imparting substantial anti-angiogenic, pro-fibrotic, and pro-inflammatory effects. Based on these data, we hypothesize that dysfunctional Tregs are essential for left ventricular (LV) remodeling, capillary rarefaction, inflammation, and disease progression in HF, and thereby are key cellular targets for immunomodulation. Three Aims will test this hypothesis. In Aim 1, we will delineate global Treg trafficking and alterations in Treg pro-inflammatory signaling in C57BL/6 mice with coronary ligation and HF, and in sham-operated controls. Tregs, and other T-cell subsets, and their inflammatory profiles will be defined in heart, blood, spleen, and mediastinal lymph nodes by flow cytometry and immunohistochemistry at serial time points after ligation, and correlated with LV and splenic remodeling and inflammation. BrdU labeling will index Treg proliferation in vivo. Moreover, using human HF biosample repositories, we will determine the abundance and distribution of Tregs in human failing hearts, and profile circulating Tregs (and other T-cells) in ambulatory patients with HF (with reduced ejection fraction) versus matched non-failing controls. In Aim 2, we will establish the role of Tregs in LV remodeling and neovascularization by selectively (and reversibly) depleting Tregs in Foxp3-DTR Tg mice with chronic HF, and then evaluating the effects on immune cell profiles, inflammation, circulating and bone marrow endothelial progenitor cells, in vivo angiogenesis, and LV remodeling. In parallel studies, the relative anti-angiogenic effects of splenic Tregs from sham mice, HF mice, and HF mice with ablation and subsequent reconstitution of Tregs will be compared using in vitro tube formation assays. In Aim 3, we will define whether dysfunctional Tregs are important mediators of the injurious cardiosplenic axis in chronic HF. CD45.2 mononuclear splenocytes from Foxp3-DTR Tg mice with either early or late HF, (corresponding to different stages of Treg dysfunction) will be adoptively transferred into CD45.1 naïve mice, with or without Treg ablation prior to transfer. The long-term effects of cell transfer on LV/splenicremodeling, inflammation, and T-cell/immune cell profiles will then be measured in recipient mice. In parallel, we will evaluate the ability of splenic Tregs from HF and sham mice to suppress activation of CD4+ and CD8+ splenic T-lymphocytes in vitro, and the role of TNFR signaling in HF Treg dysfunction via similar studies using splenic T-cells from TNFR1-/- and TNFR2-/- HF mice. By conclusively defining the role of Tregs in pathological cardiac remodeling, these studies will further our understanding of the cellular basis for inflammatory activation in chronic ischemic HF, and provide innovative perspectives as to the fundamental underpinnings of the recently discovered pro-inflammatory and tissue-injurious cardiosplenic axis. Moreover, by providing direct evidence for Tregs as anti-angiogenic and (paradoxically) pro-inflammatory mediators in HF, these studies will identify new targets for cell type-specific, rather than cytokine-specific, immunomodulation.