Investigating monocyte activation pathways in lupus

项目摘要/摘要：系统性红斑狼疮(SLE或狼疮)的病理特征是 随着自身抗体的产生和随后的组织损伤，对核自身抗原的免疫反应发生改变。 研究表明，先天免疫在狼疮中起致病作用。浆细胞样树突状细胞和 天然免疫的单核细胞识别自身抗原U1-小核糖核蛋白的单链RNA (U1-SnRNP)和dsDNA分别通过TLR 7/8和9导致干扰素-α、IL-1β和IL-18的产生 它们与狼疮的发病机制和临床表现有关。受调控的细胞死亡可以发生在不同的 形式包括上睑下垂和坏死性下垂。上睑下垂和坏死性下垂通过释放引起炎症 炎症分子，如细胞因子、趋化因子和损伤相关分子模式(DAMP)。 下睑下垂是由含有caspase-1的炎性小体激活引起的，该炎性小体可以裂解前-IL-1β和- IL-18转化为IL-1β和IL-18，以及Gasdermin D(GASDMD)转化为活性形式Gasdermin D氨基末端 片断(GASDMDN)，在上睑下垂形成膜孔中必不可少的分子。坏死性下垂 独立于caspase的发生受肿瘤坏死因子-α，受体相互作用蛋白激酶1和3(RIPK1)调节 和RIPK3)，以及下游底物假激酶混合谱系激活域(MLKL)，关键 在坏死性上睑下垂中，随着炎性分子的释放，膜破裂的分子。RIPK3和MLKL 还可通过IL-1β的释放激活NLRP3炎症体，增加上睑下垂与炎症的可能界面 坏死性下垂。研究，包括我们自己的，支持炎性小体激活、下垂和 狼疮中的坏死性下垂。我们展示了暴露于狼疮U1-SnRNP/抗-β的人MO产生IL-1和IL-18的情况。 U1-SnRNP抗体(Ab)或dsDNA/抗dsDNA抗体免疫复合物(SnRNP IC或dsDNA IC，又称狼疮IC 指两者)通过由细胞因子巨噬细胞增强的NLRP3炎症体激活 迁移抑制因子(MIF)。然而，在我们对如何实现这一目标的理解上存在巨大的科学鸿沟 在红斑狼疮中，发热和坏死通路被激活、相互作用和协同促进炎症。 分子水平与独特的临床表现有关。因此，我们将检验狼疮的假说 IC激活MO的热解和坏死通路，协同界面促进炎症和组织 在狼疮中，这些通路的激活改变有助于临床病理表现。 该提案的目的是解决这一假说：1)目的1.阐明其机制和意义 红斑狼疮中热性和坏死性分子的激活和界面；2)目的2.阐明“功能” 单核细胞改变，增强狼疮患者的下垂和坏死性下垂介导的炎症；以及 3)目的3.阐明巨噬细胞移动抑制因子在狼疮炎症中的作用 调节热性和坏死性分子。我们的研究将对狼疮的理解有很大的帮助 以及在评估和治疗狼疮患者方面开发新的方法。

Project Summary/Abstract: The pathologic hallmarks of systemic lupus erythematosus (SLE or lupus) are altered immune responses to nuclear autoantigens with autoantibody production and subsequent tissue injury. Studies have suggested a pathogenic role for innate immunity in lupus. Plasmacytoid dendritic cells and monocytes (MO) of innate immunity recognize ssRNA of the self antigen U1-small nuclear ribonucleoprotein (U1-snRNP) and dsDNA via TLRs 7/8 and 9, respectively, leading to the production of IFN-α, IL-1β and IL-18 which are linked to lupus pathogenesis and clinical manifestations. Regulated cell death can occur in distinct forms including pyroptosis and necroptosis. Pyroptosis and necroptosis cause inflammation by releasing inflammatory molecules such as cytokines, chemokines, and damage-associated molecular patterns (DAMPs). Pyroptosis is induced by the activation of the caspase-1-containing inflammasomes that cleave pro-IL-1β and - IL18 into IL-1β and IL-18, as well as gasdermin D (GASDMD) into the active form gasdermin D amino-terminal fragment (GASDMDN), the essential molecule for membrane pore formation in pyroptosis. Necroptosis that occurs independently of caspases is regulated by TNF-α, receptor-interacting protein kinases 1 and 3 (RIPK1 and RIPK3), and downstream substrate pseudokinase mixed-lineage kinase domain-like (MLKL), the critical molecule for membrane disruption with the release of inflammatory molecules in necroptosis. RIPK3 and MLKL can also activate the NLRP3 inflammasome with IL-1β release, raising the possible interface of pyroptosis and necroptosis. Studies, including our own, support the implication of the inflammasome activation, pyroptosis, and necroptosis in lupus. We showed IL-1β and IL-18 production from human MO exposed to lupus U1-snRNP/anti- U1-snRNP antibody (Ab) or dsDNA/anti-dsDNA Ab immune complex (snRNP IC or dsDNA IC, also lupus IC refers to both) through the NLRP3 inflammasome activation which is enhanced by the cytokine macrophage migration inhibitory factor (MIF). However, there is a substantial scientific gap in our understanding of how pyroptic and necroptic pathways become activated, interface, and synergize to promote inflammation in lupus at molecular levels with contributing to unique clinical manifestations. Thus, we will test the hypotheses that lupus IC activate pyroptic and necroptic pathways in MO with synergistic interface in promoting inflammation and tissue injury and that the activation of such pathways alters in lupus contributing to clinicopathologic manifestations. The goal of the proposal is to address this hypothesis with: 1) Aim 1. Elucidate the mechanism and significance of the activation and interface of pyroptic and necroptic molecules in lupus; 2) Aim 2. Elucidate the “functional” alteration in monocytes that enhances pyroptosis- and necroptosis-mediated inflammation in lupus patients; and 3) Aim 3. Elucidate the role of macrophage migration inhibitory factor in promoting inflammation in lupus via regulating pyroptic and necroptic molecules. Our study would be highly informative in understanding lupus pathogenesis as well as in developing new approaches in evaluating and treating lupus patients.