Heterotrimeric G Protein Signaling In Allergic Inflammation

过敏性炎症中的异三聚体 G 蛋白信号传导

• 批准号: 8555819
• 负责人: Kirk m Druey
• 金额: $ 50.57万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8555819
• 关键词: Allergens; Allergic; Allergic inflammation; Antigen Receptors; Antigens; Area; Basophils; Binding; Biochemical; CCL17 gene; CCL22 gene; CD4 Positive T Lymphocytes; CXCL9 gene; Cells; Chronic; Coupled; Development; Family; Fibrosis; G(q) Alpha; G-Protein-Coupled Receptors; G-substrate; GPR2 gene; GTP-Binding Protein Regulators; GTP-Binding Protein alpha Subunits; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Proteins; Gene Deletion; Genes; Genetic; Goals; Granulomatous; Guanosine Diphosphate; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Helminths; Heterotrimeric GTP-Binding Proteins; Human G(i) Alpha Proteins; Hypersensitivity; Immune; Immune response; Infection; Inflammation; Inflammatory; Interleukin-13; Interleukin-4; Investigation; Knockout Mice; Knowledge; Laboratories; Leukocytes; Ligands; Lung; Lymphocyte; Mediating; Modeling; Mus; Nose; PAR-2 Receptor; Papain; Pathway interactions; Peptide Hydrolases; Physiological; Pneumonia; Process; Production; Proteins; Research; Rhinitis; Role; Schistosoma mansoni; Schistosome Granuloma; Signal Transduction; Site; Skin; Source; T-Lymphocyte; Th1 Cells; Th2 Cells; Time; Tissues; allergic response; base; chemokine; crosslink; cytokine; desensitization; granulocyte; lymph nodes; mast cell; migration; pathogen exposure; programs; pulmonary granuloma; receptor; receptor coupling; release of sequestered calcium ion into cytoplasm; response; trafficking

Mast cells (MCs), basophils, and lymphocytes are integral to the development of an allergic response. Degranulation of MCs and granulocytes, and cytokine production by T cells is induced primarily by cross-linking of the receptor for antigen. However, allergic inflammation may also be generated through activation of receptors coupled to heterotrimeric G proteins (GPCRs). The purpose of this study is to understand mechanisms of intracellular G-protein-coupled signal transduction in immune cells and subsequent pathways to inflammation. GPCRs activate heterotrimeric G proteins, which bind guanosine triphosphate (GTP) in exchange for guanosine diphosphate (GDP). The GTP-bound form of the G protein alpha subunit induces downstream signaling cascades, including intracellular calcium flux responsible for MC/basophil degranulation. This project focuses on a family of regulators of G protein signaling (RGS proteins), which inhibit the function of G alpha-i and G alpha-q, but not G alpha-s, proteins by increasing their GTPase activity. G alpha subunits oscillate between GDP- (inactive) and GTP- (active) bound forms based on ligand occupancy of the associated receptor. The GTPase accelerating (GAP) activity of RGS proteins limits the time of interaction of active G-alpha and its effectors, resulting in desensitization of GCPR signaling. Despite a growing body of knowledge concerning the biochemical mechanisms of RGS action, relatively little is known about the physiological role of these proteins in allergic inflammation. A major area of investigation is the recruitment of inflammatory cells to sites of allergic inflammation. Chemokines are a major class of compounds acting on GPCRs in leukocytes, which orchestrate cell trafficking during the immune response. We found that RGS16 is enriched in activated/effector T lymphocytes. We showed that RGS16 constrains pulmonary inflammation by regulating chemokine-induced T cell trafficking in response to challenge with the helminth Schistosoma mansoni. Naive RGS16-deficienct mice were primed for inflammation by accumulation of CCR10+ T cells in the lung. Upon pathogen exposure, these mice developed more robust granulomatous lung fibrosis than wild-type counterparts. Distinct Th2 or putative Th17 subsets expressing CCR4 or CCR10 accumulated more rapidly in lungs of Rgs16 gene-deleted mice following challenge and produced proinflammatory cytokines IL-13 and IL-17B. Th1 and Th2 cells lacking RGS16 migrated more than wild-type counterparts to the chemokines CXCL9 and CCL17, respectively. RGS16-deficient Th2 cells localized aberrantly in challenged lungs. T lymphocytes were partially excluded from lung granulomas in Rgs16 knockout mice, instead forming peribronchial/perivascular aggregates. Thus, RGS16-mediated confinement of T cells to Schistosome granulomas mitigates widespread cytokine-mediated pulmonary inflammation. A second research area is the mechanisms controlling basophil trafficking in allergic responses. Many allergens contain intrinsic proteolytic activity and bind protease activated GPCRs. We studied the response of immune cells including basophils and T cells to the model protease allergen papain. Although sensitization to protease allergens, such as papain, helminth infection, chronic allergic skin inflammation, and nasal rhinitis are associated with basophil recruitment to inflammed tissue or to draining lymph nodes (LNs), the precise role of these granulocytes in allergic inflammation is incompletely understood. Basophils have the capacity to present antigen to naive T cells and promote TH2 differentiation directly or indirectly through IL-4 production. We studied how papain induces basophil migration to LNs and the contribution of various leukocytes to papain-induced immune responses. We immunized mice in the footpad with papain and studied leukocyte recruitment and inflammatory cytokine and chemokine production in the draining popliteal LNs. Papain directly activated naive T cells through protease-activated receptor (PAR)2 to initiate a chemokine/cytokine program that includes CCL17, CCL22, and IL-4. Papain-triggered chemokine and cytokine production and basophil trafficking to LNs were dependent on both CD4 T cells and PAR2 and were strongly reduced in the absence of CCR4, the primary receptor for CCL17/CCL22.

肥大细胞（MC）、嗜碱性粒细胞和淋巴细胞是过敏反应发展的组成部分。 MC和粒细胞的脱粒以及T细胞的细胞因子产生主要由抗原受体的交联诱导。 然而，过敏性炎症也可能通过激活与异源三聚体G蛋白（GPCR）偶联的受体而产生。本研究的目的是了解免疫细胞内G蛋白偶联信号转导的机制以及随后的炎症途径。 GPCR激活异源三聚体G蛋白，其结合三磷酸鸟苷（GTP）以交换二磷酸鸟苷（GDP）。G蛋白α亚基的GTP结合形式诱导下游信号级联，包括负责MC/嗜碱性粒细胞脱粒的细胞内钙流。该项目的重点是G蛋白信号传导调节因子（RGS蛋白）家族，其通过增加GT3活性抑制G α-i和G α-q蛋白的功能，但不抑制G α-s蛋白的功能。G α亚基基于相关受体的配体占有率在GDP-（非活性）和GTP-（活性）结合形式之间振荡。RGS蛋白的GTP酶加速（GAP）活性限制了活性G-α及其效应物相互作用的时间，导致GCPR信号转导的脱敏。尽管关于RGS作用的生化机制的知识越来越多，但关于这些蛋白质在过敏性炎症中的生理作用的知识相对较少。 研究的一个主要领域是炎症细胞向过敏性炎症部位的募集。趋化因子是作用于白细胞中的GPCR的主要类别的化合物，其在免疫应答期间协调细胞运输。我们发现RGS 16富含活化/效应T淋巴细胞。我们发现RGS 16通过调节趋化因子诱导的T细胞运输来抑制肺部炎症，以响应曼氏血吸虫的挑战。通过CCR 10 + T细胞在肺中的积累来引发初始RGS 16缺陷小鼠的炎症。在病原体暴露后，这些小鼠比野生型小鼠发展出更强的肉芽肿性肺纤维化。表达CCR 4或CCR 10的不同Th 2或推定的Th 17亚群在Rgs 16基因缺失小鼠的肺中在攻击后更迅速地积累，并产生促炎细胞因子IL-13和IL-17 B。 缺乏RGS 16的Th 1和Th 2细胞比野生型对应物分别迁移到趋化因子CXCL 9和CCL 17。RGS 16缺陷型Th 2细胞异常定位于受攻击的肺中。在Rgs 16基因敲除小鼠中，T淋巴细胞被部分排除在肺肉芽肿之外，而不是形成支气管周围/血管周围聚集体。因此，RGS 16介导的T细胞局限于血吸虫肉芽肿减轻了广泛的精氨酸介导的肺部炎症。 第二个研究领域是过敏反应中嗜碱性粒细胞运输的控制机制。许多过敏原含有内在的蛋白水解活性并结合蛋白酶激活的GPCR。我们研究了免疫细胞包括嗜碱性粒细胞和T细胞对模型蛋白酶过敏原木瓜蛋白酶的反应。尽管对蛋白酶过敏原（如木瓜蛋白酶）、蠕虫感染、慢性过敏性皮肤炎症和鼻鼻炎的致敏与嗜碱性粒细胞向炎症组织或引流淋巴结（LN）的募集有关，但这些粒细胞在过敏性炎症中的确切作用尚不完全清楚。嗜碱性粒细胞具有将抗原呈递给初始T细胞并通过IL-4产生直接或间接促进TH 2分化的能力。我们研究了木瓜蛋白酶如何诱导嗜碱性粒细胞迁移到淋巴结和各种白细胞对木瓜蛋白酶诱导的免疫反应的贡献。我们用木瓜蛋白酶免疫小鼠的足垫，并研究了白细胞募集和炎症细胞因子和趋化因子的生产在引流腘淋巴结。木瓜蛋白酶通过蛋白酶激活受体（PAR）2直接激活初始T细胞，以启动包括CCL 17、CCL 22和IL-4的趋化因子/细胞因子程序。木瓜蛋白酶触发的趋化因子和细胞因子的产生以及嗜碱性粒细胞向LN的运输依赖于CD 4 T细胞和PAR 2，并且在不存在CCL 17/CCL 22的主要受体CCR 4的情况下强烈减少。