Pathologic Myeloid Activation in Pediatric Burn Injury

摘要 烧伤是儿童创伤的主要原因，导致终生的生理和心理疾病。 幼儿，特别是那些5岁以下的儿童，是一个高度脆弱和处于危险中的人群 过度的全身性宿主反应导致多器官系统功能障碍(MODS)。不幸的是， 我们目前的许多烧伤治疗策略都是从成人研究中推断出来的，或者被广泛应用于 年龄谱。这些方法没有考虑到儿科患者独特的宿主免疫反应。 在儿童时期的不同年龄阶段。了解由以下原因引起的年龄特异性免疫功能障碍 儿童烧伤将解决开发新的个性化干预措施所需的关键知识缺口 对于这些高度脆弱的人群来说。我们最主要的假设是烧伤会导致病理性髓系 儿科宿主中的激活，导致髓系来源的抑制细胞(MDSCs)扩张，不理想 单核细胞功能、淋巴细胞减少和淋巴细胞功能障碍。此外，我们认为这种影响既与年龄有关- 以及烧伤大小依赖，这样年轻的患者更容易进入病理性髓系状态 激活会增加对烧伤脓毒症和免疫抑制的易感性。我们有两个具体目标：1) 确定儿童烧伤是否导致病理性髓系激活，增加循环 免疫抑制的MDSCs，导致单核细胞功能障碍和淋巴细胞数量减少 功能；以及，2)检查儿童烧伤是否诱导了一种独特的血液髓系和淋巴系 小面积和大面积烧伤儿童患者的转录组分析 和表型变化。为了实现这些目标，我们打算招募两个不同的儿科烧伤患者队列。 他们的年龄和烧伤的大小。我们打算将1-5岁的儿童(n=30)与较小的(15%TBSA， N=15)或更大(15%-30%TBSA，n=15)烧伤，9-15岁儿童(n=30)烧伤面积与TBSA匹配 每组15例，年龄匹配的非损伤对照组30例。使用流式细胞术，我们将确定MDSC如何 随着时间的推移，数量和表型受到儿科年龄和烧伤面积的影响。同样，我们将调查 骨髓间充质干细胞数量和功能与T细胞增殖和干扰素γ产生易感性及缺失的关系 (Elispot)。此外，我们将确定外周血单核细胞HLA-DR表达、单核细胞分布的变化 并量化体外刺激的单核肿瘤坏死因子-α的产生(ELISpot)。在这些元素的子集中 患者，我们将通过以下方式执行单细胞RNA-Seq/Cite-Seq(转录本和表位的细胞索引 烧伤后早期(第4天)和后期(第30天)的血液髓系和淋巴样细胞的测序)。 我们的最终目标是开发新的治疗范例，以个性化的方法治疗儿童 确保这一弱势群体“…”充分发挥(S)他们健康、富有成效的生活的潜力。

ABSTRACT Burn injury is a leading cause of trauma in children, resulting in life-long physical and psychological morbidities. Young children, particularly those under 5-years of age, represent a highly vulnerable and at-risk population for an exaggerated systemic host response leading to multiple organ system dysfunction (MODS). Unfortunately, much of our current burn treatment strategies are extrapolated from adult studies or are broadly applied across the age spectrum. These approaches fail to consider the unique host immune responses of pediatric patients across the different age stages of childhood. Understanding age-specific immune dysfunction resulting from pediatric burn injury will address a key gap of knowledge necessary to develop novel personalized interventions for this highly vulnerable population. Our overarching hypothesis is that burn injury induces pathologic myeloid activation in the pediatric host, resulting in expansion of myeloid-derived suppressor cells (MDSCs), suboptimal monocyte function, lymphopenia and lymphocyte dysfunction. Additionally, we believe this effect is both age- and burn size-dependent, such that younger patients more commonly enter a state of pathologic myeloid activation with increased susceptibility to burn sepsis and immunosuppression. We have two specific aims: 1) to determine whether pediatric burn injury leads to pathologic myeloid activation, increasing circulating immunosuppressive MDSCs, engendering dysfunctional monocyte and decreasing lymphocyte numbers and function; and, 2) to examine whether pediatric burn injury induces a unique blood myeloid and lymphoid transcriptome in young and older pediatric patients with small and larger burns that can explain the functional and phenotypic changes. To achieve these goals, we intend to enroll two pediatric burn patient cohorts differing in their age and burn size. We intend to compare children 1–5 years old (n=30) with either small (<15% TBSA, n=15) or larger (15-30% TBSA, n=15) burns, with children 9-15 years old (n=30) with TBSA-matched burn sizes (n=15 each), and age-matched non-injured controls (n=30). Using flow cytometry, we will determine how MDSC numbers and phenotypes are influenced by pediatric age and burn size over time. Similarly, we will investigate MDSC numbers and function in relation to susceptibility to and loss of T-cell proliferation and IFNγ production (ELISpot). Additionally, we will determine changes in blood monocyte HLA-DR expression, monocyte distribution width (MDW) and quantify ex vivo stimulated mononuclear TNF-α production (ELISpot). In a subset of these patients, we will perform single cell RNA-seq/CITE-Seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing) of blood myeloid and lymphoid cells in the early (day 4) and later (day 30) periods after burn injury. Our ultimate goal is to develop novel treatment paradigms that treat children with a personalized approach ensuring that this vulnerable population “…achieve(s) their full potential for healthy productive lives.”