Arginine Availability and Metabolism in the Immune Evasion of H. pylori

幽门螺杆菌免疫逃避中的精氨酸利用率和代谢

• 批准号: 8528323
• 负责人: Keith T. Wilson
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8528323
• 关键词: A Mouse; American; Apoptosis; Area; Arginine; Bacteria; Biological Markers; Bone Marrow; Cancer Etiology; Cationic Amino Acid Transporter 2; Cells; Cessation of life; Chimera organism; Clinical; Colombia; DL-alpha-Difluoromethylornithine; Dysplasia; Exhibits; Futile Cycling; Future; Gastric Tissue; Gastritis; Generations; Gerbils; Health; Helicobacter Infections; Helicobacter pylori; High-Risk Cancer; Host Defense; Immune; Immune Tolerance; Immune response; Immunity; Immunosuppression; In Vitro; Infection; Inflammation; Inflammation Mediators; Inflammatory Response; Intervention; Investigation; Knockout Mice; Lead; Link; Lymphocyte; Malignant Neoplasms; Mediating; Metabolism; Mus; NOS2A gene; Natural Immunity; Nitric Oxide; Organism; Ornithine; Ornithine Decarboxylase; Ornithine Decarboxylase Inhibitor; Output; Parasitic infection; Pathway interactions; Peptic Ulcer; Phagocytosis; Phenotype; Polyamines; Population; Prevalence; Process; Production; Progress Reports; Proteins; Reporting; Risk; Risk Assessment; Role; Site; Splenocyte; Stomach; Stomach Carcinoma; Testing; Therapeutic Intervention; Tissues; Transgenic Organisms; Translations; Veterans; Virulent; Woman; Work; adaptive immunity; antimicrobial; arginase; biobank; cancer risk; carcinogenesis; cytokine; extracellular; human NOS2A protein; human subject; improved; inhibitor/antagonist; insight; killings; macrophage; malignant stomach neoplasm; novel; novel strategies; pathogen; protein expression; response; treatment strategy; tumor; uptake

DESCRIPTION (provided by applicant): The acquisition of Helicobacter pylori and its clinical sequelae of peptic ulcer disease and gastric cancer remain substantial health concerns for our Veterans. H. pylori infects half of the world's population, causes peptic ulcers in 10% and gastric cancer in 1% of those infected, and it is the second leading cause of cancer death worldwide. American Servicemen/women are exposed to H. pylori in regions of the world where infection rates are very high and strains associated with high cancer risk are prevalent. Thus, improved understanding of the defective immune response is crtical. We have gained new insights into why the sustained immune response to H. pylori fails to eradicate the organism. Our work has focused on the role of L-arginine (L-Arg) in the macrophage response to H. pylori. L-Arg is the common substrate for two divergent enzymatic pathways: inducible nitric oxide (NO) synthase (iNOS), that generates high output NO; and arginase, consisting of two forms, arginase I (Arg1) and arginase II (Arg2) that generate L-ornithine, which is the substrate for polyamine synthesis by ornithine decarboxylase (ODC). We have shown that the regulator of L-Arg uptake in macrophages, cationic amino acid transporter-2 (CAT2), is required for protein expression of iNOS and that its function is inhibited by polyamines in a process that restricts NO generation and leads to sustained bacterial colonization and inflammation. In addition, we found that Arg2 is at the center of the ineffective response to H. pylori. In the current paradigm, M1 macrophages express iNOS and produce pro-inflammatory mediators involved in host defense against extracellular infections, while M2 cells express Arg1, are involved in host response to parasitic infection, and are implicated as tumor-associated macrophages. However, in response to H. pylori, macrophages are not M1 or M2 type. They express iNOS and Arg2, but not Arg1. Upon inhibition or knockdown of Arg2, or in cells from Arg2-/- mice, there is enhanced iNOS protein translation/expression and NO generation, indicating that H. pylori-stimulated cells have sub-optimal M1 response. Arg2-/- mice exhibit increased immune responses to H. pylori infection that are correlated with decreased colonization, and we have linked enhanced host defense to more gastric macrophages (GMacs), which undergo less apoptosis and have more iNOS/NO production, and an enhanced Th1/Th17 response. We now show that a substantial portion of GMacs in the H. pylori-infected stomach are regulatory macrophages (Mregs), which may contribute to persistence of the infection. We hypothesize that the competition between iNOS and Arg2 for L-Arg in GMacs leads to a futile cycle and a compromise of host defense that results in H. pylori persistence, inflammation, and cancer risk, and is a site for therapeutic intervention. Our specific aims are: 1 To determine if immunosuppressive effects of Arg2 are due to inhibition of iNOS. We will generate Arg2-/-iNOS-/- double knockout mice that will be compared to wild-type (WT), Arg2-/-, and iNOS-/- mice, and bone marrow chimeras will be used, to examine A) H. pylori colonization and gastritis; B) GMac phenotype and function; and C) Adaptive immunity in gastric tissues, splenocytes, and lymphocytes. 2.) To determine if effects of Arg2 are mediated by downstream polyamines. We will generate Arg2-/-ODC+/- mice, and administer DFMO (ODC inhibitor) to WT and Arg2-/- mice, and assess: A) H. pylori colonization and gastritis; B) GMac phenotype and function; and C) Adaptive immunity. 3) To determine if Arg2 facilitates H. pylori-induced gastric carcinogenesis, is a target for intervention, and is a biomarker for identifying gastric cancer ris in Veterans. We will utilize: A) Mice that develop dysplasia/cancer, crossed with Arg2-/- mice. B) Gerbils that develop dysplasia/cancer, treated with an arginase inhibitor, BEC. C) Gastric tissues and H. pylori isolates from human subjects in two biorepositories: from areas of low and high gastric cancer risk in Colombia, and from Veterans at the Nashville VAMC. These studies will have a major impact on our understanding of H. pylori immunopathogenesis and gastric carcinogenesis, and will lead to new approaches for risk assessment and treatment.

描述（由申请人提供）： 对幽门螺杆菌的收购及其临床后遗症是消化性溃疡疾病和胃癌的临床后遗症，对我们的退伍军人仍然存在很大的健康问题。幽门螺杆菌感染了全球一半的人口，在1％的感染者中导致10％的消化性溃疡，而胃癌则是胃癌，这是全球癌症死亡的第二大主要原因。美国军人/妇女暴露于世界各地的幽门螺杆菌，那里的感染率很高，并且与高癌症风险相关的菌株很普遍。因此，对有缺陷的免疫反应的提高理解是曲折的。我们已经获得了新的见解，说明为什么对幽门螺杆菌的持续免疫反应无法消除生物体。我们的工作集中在L-精氨酸（L-ARG）在幽门螺杆菌巨噬细胞反应中的作用。 L-ARG是两种发散酶促途径的常见底物：诱导型一氧化氮（NO）合酶（iNOS），它会产生高输出NO；和精氨酸酶，由两种形式的精氨酸酶I（arg1）和精氨酸酶II（arg2）组成，它们生成L- or-骨氨酸，这是鸟氨酸脱羧酶（ODC）的多胺合成的底物。我们已经表明，巨噬细胞中L-Arg摄取的调节剂，阳离子氨基酸转运蛋白2（CAT2）是iNOS的蛋白质表达所必需的，并且其功能受到抑制 通过多胺在不限制任何产生并导致细菌定植和炎症的过程中进行的多胺。此外，我们发现ARG2是对幽门螺杆菌的无效反应的中心。在当前的范式中，M1巨噬细胞表达iNOS并产生参与宿主防御细胞外感染的促炎性介质，而M2细胞表达ARG1，参与宿主对寄生虫感染的反应，并被视为肿瘤相关的巨噬细胞。但是，为了响应幽门螺杆菌，巨噬细胞不是M1或M2型。他们表达iNOS和arg2，但不是arg1。在抑制或敲低arg2或在arg2 - / - 小鼠的细胞中，iNOS蛋白翻译/表达有增强，没有产生，表明幽门螺杆菌刺激的细胞具有亚最佳的M1反应。 ARG2 - / - 小鼠对幽门螺杆菌感染的免疫反应增加，与降低的定殖相关，并且我们将增强的宿主防御与更多的胃巨噬细胞（GMAC）联系起来，这些胃巨噬细胞（GMAC）的细胞凋亡较少，并且具有更多的iNOS/no产生，并且具有增强的TH1/TH1/TH1/TH1/TH17响应。我们现在表明，幽门螺杆菌感染的胃中的大部分GMAC是调节性巨噬细胞（MREGS），这可能有助于感染的持久性。我们假设INOS和ARG2在GMAC中为L-ARG之间的竞争导致了徒劳的周期和托管防御的妥协，从而导致幽门螺杆菌持久性，炎症和癌症风险，并且是治疗干预的部位。我们的具体目的是：1确定ARG2的免疫抑制作用是否归因于iNOS的抑制。我们将生成Arg2 - / - iNOS - / - 双敲除小鼠，将使用野生型（WT），ARG2 - / - 和Inos - / - 小鼠以及骨髓嵌合体进行比较，以检查A）H。H. pylori colonization and gastripial and gulori chimeris and h. b）GMAC表型和功能； c）胃组织，脾细胞和淋巴细胞的适应性免疫。 2.）确定ARG2的影响是否由下游多胺介导。我们将生成arg2 - / - odc +/-小鼠，并将DFMO（ODC抑制剂）施用到WT和ARG2 - / - 小鼠，并评估：A）H。Pylori定殖和胃炎； b）GMAC表型和功能； c）适应性免疫。 3）确定ARG2是否促进幽门螺杆菌诱导的胃癌发生，是干预的靶标，并且是鉴定退伍军人胃癌RIS的生物标志物。我们将利用：a）患有发育异常/癌症的小鼠与Arg2 - / - 小鼠交叉。 b）患有精氨酸酶抑制剂治疗的发育异常/癌症的沙鼠，Bec。 c）来自两个生物症状的人类受试者的胃组织和幽门螺杆菌分离株：来自哥伦比亚低胃癌风险和高胃癌风险的地区，以及纳什维尔VAMC的退伍军人。这些研究将对我们对幽门螺杆菌免疫发育和胃癌发生的理解产生重大影响，并将导致风险评估和治疗的新方法。