MDSC Polarization and Helicobacter-induced Gastric Metaplasia

胃化生改变通常发生在胃上皮对慢性胃炎的反应时 幽门螺杆菌(Hp)等生物体引起的炎症。我们之前已经证明了一个子集 干扰素调节的髓系细胞表达Gli1转录的直接靶点Schlafen4(Slfn4) 因子和表现T细胞抑制功能指示髓系来源的抑制细胞(MDSCs)。这些 粒细胞髓系衍生抑制细胞亚群(Gr-MDSCs)参与胃病的发生 肠化生和痉挛多肽表达化生(SPEM)。我们认为残骸 从受损的胃上皮细胞和免疫细胞以及死亡的细菌诱导信号转导 途径产生病原体识别配体，统称为损伤激活的分子模式或 湿透了。1型干扰素(IFN)通常由潮湿的配体诱导，例如HMGB1、线粒体和 未甲基化的CpG DNA。我们最近发现人类TLR9启动子中的SNP与 萎缩、IM和GAC。此外，TLR9SNP产生了一个NFB结合位点，导致TLR9值升高 表情。浆细胞样树突状细胞和胃上皮细胞共同检测幽门螺杆菌感染 (GEC)诱导TLR9表达，最终分泌1型干扰素(α/β)。因此，除了主机之外， 注射幽门螺杆菌毒力因子CagA的信号，幽门螺杆菌残留物和细胞碎片能够 启动免疫抑制反应。因为我们之前已经证明了这些SLFn4+的存在 MDSCs与早期肿瘤前改变相关，我们假设 免疫抑制细胞(SLFN+-MDSCs)和胃上皮细胞刺激前馈信号， 最终，在胃癌出现之前，将上皮重新编程为化生。刺猬 Gli1和干扰素α协同诱导SLFN4+/SLFN12L+-MDSCs。提出了三个具体目标： 在目标1中，我们将确定潮湿配体(幽门螺杆菌DNA)对产生干扰素的pDC与 胃上皮细胞。在目标2中，我们将演示Schlafens如何保护MDSC子集免受自身 干扰素诱导的ROS破坏。在目标3中，我们将演示PDE抑制如何阻断SLFN4/SLFN12L+- 在胃肿瘤发生的固有模型中，MDSCs和调节免疫微环境。一个 结合小鼠模型和人类有机化合物将被用来理解潮湿配体在 在慢性炎症发生后塑造免疫微环境。有条件删除slfn4 和敲除人类同源基因SLFN12L将被用来剖析这些Schlafen是如何保护干扰素的- 来自细胞死亡的反应性MDSCs。最后，由于调节免疫微环境起着重要的作用 在肿瘤生长中的作用，我们将检查是否有小分子干扰或消除这些SLFN4/SLFN12L 影响肿瘤生长。完成这些目标将使我们更好地理解这一点的重要性 免疫调节细胞亚群是由小分子诱导、维持并最终靶向的。

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.