Role of monocytes and Th17 cells in the pathogenesis of graft-versus-host disease - influence of S100 proteins and Hsp90

移植物抗宿主病（GvHD）是异体干细胞移植后发病和死亡的主要原因。然而，GvHD的病理生理机制尚不完全清楚。我们的研究小组可以证明，与没有GvHD的患者相比，急性或慢性GvHD患者体内活化的单核细胞诱导了更高水平的Th17细胞。在拟建的项目中，将对急性或慢性GvHD患者的单核细胞以及单核细胞诱导的Th17细胞进行表征。在自身免疫性疾病中，已知CD14+CD16+促炎单核细胞亚群可分为两个亚群：CD14+CD16++单核细胞和CD14++CD16+单核细胞，后者诱导高水平的促炎Th17细胞。在这个项目中，这些单核细胞亚群的百分比将被确定并分类在患有和没有急性或慢性GvHD的患者中。产生IL-17的T细胞（Th17.1细胞）的一个亚群表达p-糖蛋白（多药耐药1型蛋白（MDR1）），并对糖皮质激素的免疫抑制具有抗性。因此，我们将从MDR- th17和MDR+Th17.1细胞的诱导角度来分析所分类的单核细胞亚群。此外，还将研究免疫调节如调节性T细胞（Tregs）、tgf - β或糖皮质激素对GvHD患者单核细胞诱导的Th17细胞的影响。将我们的结果与所研究患者的临床病程相关联，我们希望证明这样的假设，即发展为严重或慢性GvHD的高风险患者可能通过CD14++CD16+单核细胞或Th17.1细胞水平升高来识别。这可能允许实施风险分层治疗方法。此外，S100蛋白作为已知的炎症放大器的影响及其与热休克蛋白（Hsp） 90的相互作用将在单核细胞中进行研究。在我们之前的工作中，在急性和慢性GvHD患者的肠组织、粪便和血清中可以检测到S100蛋白的升高，这表明在GvHD期间这些吞噬细胞特异性蛋白的释放。发现S100蛋白刺激单核细胞可促进Th17的发育，而阻断Hsp90可抑制Th17的发育。因此，S100蛋白与Hsp90信号通路的交叉将在计划的研究中通过微阵列分析进行研究，并在蛋白水平上进行验证。了解GvHD中炎症细胞的激活和调节机制对于确定该疾病破坏炎症的核心因素至关重要。我们的研究结果为新的特异性治疗策略铺平了道路，例如抑制Hsp90在这些经常多病的患者中。

Graft-versus-host disease (GvHD) is a major cause of morbidity and mortality after allogeneic stem cell transplantation. However, the pathophysiology of GvHD is not fully understood. Our group could demonstrate that in vivo activated monocytes of patients with acute or chronic GvHD induced higher levels of Th17 cells compared to monocytes of patients without GvHD. In the proposed project monocytes as well as monocyte-induced Th17 cells of patients with acute or chronic GvHD will be characterized. In autoimmune diseases it is known that the CD14+CD16+ proinflammatory monocyte subpopulation can be divided into two subgroups: CD14+CD16++ monocytes and CD14++CD16+ monocytes whereby the latter induces high levels of proinflammatory Th17 cells. In this project the percentage of these monocyte subpopulations will be determined and sorted in patients with and without acute or chronic GvHD. A subgroup of IL-17 producing T cells (Th17.1 cells) express the p-glycoprotein (multi-drug resistance type 1 protein (MDR1)) and are resistant to immunosuppression with glucocorticoids. Therefore, the sorted monocyte subpopulations will be analyzed in terms of induction of MDR-Th17 and MDR+Th17.1 cells. Additionally, the influence of immunoregulation e.g. regulatory T cells (Tregs), TGFbeta or glucocorticoids on monocyte-induced Th17 cells of patients with GvHD will be investigated. Correlating our results with the clinical course of the studied patients we would like to prove the hypothesis that patients with high risk for developing severe or chronic GvHD might be identified by elevated levels of CD14++CD16+ monocytes or Th17.1 cells. This may allow the implementation of risk stratified therapeutic approaches. Furthermore, the impact of S100 proteins as known amplifier of inflammation and their interplay with heat shock protein (Hsp) 90 will be investigated in monocytes. In our previous work, elevated levels of S100 proteins could be detected in the bowel tissue, stool and serum of patients with acute and chronic GvHD demonstrating the release of these phagocyte-specific proteins during GvHD. Stimulation of monocytes with S100 proteins was found to promote Th17 development which could be inhibited by blockade of Hsp90. Therefore, the intersection of the signaling pathways of S100 proteins and Hsp90 will be investigated by microarray analysis and verified on protein level in the planned study. The understanding of the mechanisms of activation and regulation of inflammatory cells in GvHD is essential for the identification of central factors underlying the destroying inflammation of this disease. Our results pave the way for novel specific therapeutic strategies, e.g. inhibition of Hsp90 in these often multimorbid patients.