MDSC Polarization and Helicobacter-induced Gastric Metaplasia

胃中的化生变化通常在胃上皮对慢性炎症反应时发生。 由诸如幽门螺杆菌（H. pylori）。我们之前证明了一个子集 的干扰素（IFN）调节的骨髓细胞表达Schlafen 4（Slfn 4），一种Gli 1转录的直接靶点， 因子，并表现出T细胞抑制功能，指示髓源性抑制细胞（MDSC）。这些 粒细胞骨髓源性抑制细胞亚群（Gr-MDSCs）有助于胃粘膜上皮细胞的出现。 肠化生和痉挛性多肽表达化生（SPEM）。我们认为碎片 从受损的胃上皮细胞和免疫细胞以及垂死的细菌诱导信号转导 途径产生病原体识别配体，统称为损伤激活分子模式， 阻尼器。1型干扰素（IFN）通常由DAMP配体诱导，例如，HMGB 1，线粒体和 未甲基化的CpG DNA。我们最近发现，人TLR 9启动子内的SNP与以下相关： 萎缩、IM和GAC。此外，TLR 9 SNP产生NF κ B B结合位点，导致更高的TLR 9 表情H.浆细胞样树突状细胞（pDC）和胃上皮细胞共同感受幽门螺杆菌感染 (GEC)诱导TLR 9表达并最终分泌1型IFN（IFNα/β）。因此，除了主机 注射H. pylori毒力因子CagA、H.幽门螺杆菌残余物和细胞碎片能够 启动免疫抑制反应。由于我们以前表明，这些Slfn 4 +- MDSC与早期肿瘤前变化相关，我们假设MDSC的一个子集之间的串扰， 免疫抑制细胞（SLFN+-MDSC）和胃上皮细胞刺激前馈信号， 最终在胃癌出现之前将上皮细胞重新编程为化生。刺猬 信号转导（Gli 1）和IFNα协同诱导Slfn 4 +/SLFN 12 L +-MDSC。提出了三个具体目标： 在目标1中，我们将确定DAMP配体（H。pylori DNA）对产生IFN β的pDC的作用， 胃上皮细胞在目标2中，我们将展示Schlafens如何保护MDSC的一个子集免受自 IFN诱导的ROS的破坏。在目标3中，我们将证明PDE抑制如何阻断Slfn 4/SLFN 12 L +-。 MDSC和调节免疫微环境在胃肿瘤发生的自体模型。一 小鼠模型和人类类器官的组合将用于理解DAMP配体在 在慢性炎症发生后塑造免疫微环境。Slfn 4的条件性缺失 并敲除人类直系同源物SLFN 12 L将用于剖析这些Schlafens如何保护IFN-γ 响应性MDSC免于细胞死亡。最后，由于调节免疫微环境在免疫系统中起着重要的作用， 在肿瘤生长中的作用，我们将研究是否小分子，破坏或消除这些SLFN 4/SLFN 12 L 影响肿瘤生长。这些目标的完成将导致更好地理解这一重要性， 免疫调节细胞的亚群被小分子诱导、维持并最终靶向。

Metaplastic changes in the stomach typically develop when the gastric epithelium responds to chronic inflammation induced by such organisms as Helicobacter pylori (H. pylori). We previously showed that a subset of interferon (IFN)-regulated myeloid cells express Schlafen4 (Slfn4), a direct target of the Gli1 transcription factor and exhibit T cell suppressor function indicative of myeloid-derived suppressor cells (MDSCs). These granulocytic myeloid-derived suppressor cell subset (Gr-MDSCs) contribute to the emergence of gastric intestinal metaplasia and spasmolytic-polypeptide-expressing metaplasia (SPEM). We propose that debris from damaged gastric epithelia and immune cells as well as dying bacteria induce a signal transduction pathway generate pathogen recognition ligands collectively known as damage-activated molecular patterns or DAMPs. Type 1 interferons (IFNs) are typically induced by DAMP ligands, e.g., HMGB1, mitochondrial and unmethylated CpG DNA. We have recently found that a SNP within the human TLR9 promoter correlates with atrophy, IM, and GAC. Moreover, the TLR9 SNP creates an NFB binding site resulting in higher TLR9 expression. H. pylori infection sensed by both plasmacytoid dendritic cells (pDC) and gastric epithelial cells (GEC) induces TLR9 expression and ultimately secrete type 1 IFNs (IFNα/β). Thus, in addition to host signaling from injection of the H. pylori virulence factor CagA, H. pylori remnants and cell debris are capable of initiating an immune suppressor response. Since we previously showed that the presence of these Slfn4+- MDSCs correlates with early pre-neoplastic changes, we hypothesize that crosstalk between a subset of immune suppressor cells (SLFN+-MDSCs) and gastric epithelial cells stimulate feedforward signals that ultimately re-program the epithelium towards metaplasia, before the appearance of gastric cancer. Hedgehog signaling (Gli1) and IFNα synergistically induce Slfn4+/SLFN12L+-MDSCs. Three Specific aims are proposed: In Aim 1, we will determine the impact of DAMP ligands (H. pylori DNA) on IFN-producing pDCs versus gastric epithelial cells. In Aim 2, we will demonstrate how Schlafens protect a subset of MDSCs from self- destruction by IFN-induced ROS. In Aim 3, we will demonstrate how PDE inhibition blocks Slfn4/SLFN12L+- MDSCs and modulates the immune microenvironment in an autochthonous model of gastric tumorigenesis. A combination of mouse models and human organoids will be used to understand the role of DAMP ligands in shaping the immune microenvironment after chronic inflammation has occurred. Conditional deletion of Slfn4 and knockdown of the human ortholog SLFN12L will be used to dissect how these Schlafens protect the IFN- responsive MDSCs from cell death. Finally, since modulating the immune microenvironment plays a significant role in tumor growth, we will examine whether small molecules that disrupt or eliminate these Slfn4/SLFN12L impact tumor growth. Completion of these aims will result in a better understanding of the how this important subset of immune modulatory cells are induced, maintained and ultimately targeted by small molecules.