Investigating monocyte activation pathways in lupus

系统性红斑狼疮（SLE或狼疮）的病理特征是 对核自身抗原的免疫应答改变，产生自身抗体，随后发生组织损伤。 研究表明先天免疫在狼疮中的致病作用。浆细胞样树突状细胞和 先天免疫的单核细胞（MO）识别自身抗原U1-小核核糖核蛋白的ssRNA （U1-snRNP）和dsDNA分别通过TLR 7/8和9，导致IFN-α、IL-1β和IL-18的产生 其与狼疮发病机制和临床表现有关。调节性细胞死亡可以发生在不同的 包括焦亡和坏死。细胞凋亡和坏死性凋亡通过释放 炎症分子，如细胞因子、趋化因子和损伤相关分子模式（DAMP）。 焦亡是由含有caspase-1的炎性体激活诱导的，该炎性体裂解pro-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 片段（GASDMDN），在细胞凋亡中膜孔形成的必要分子。坏死性下垂， 独立于半胱天冬酶发生，受TNF-α、受体相互作用蛋白激酶1和3（RIPK 1）调节 和RIPK 3），以及下游底物假激酶混合谱系激酶结构域样（MLKL）， 在坏死性凋亡中释放炎性分子导致膜破裂。RIPK 3和MLKL 还可以通过IL-1β释放激活NLRP 3炎性体，提高可能的焦亡界面， 坏死性凋亡包括我们自己在内的研究支持炎性小体激活、焦亡和 狼疮的坏死性凋亡我们发现，暴露于狼疮U1-snRNP/抗-IFN-γ的人MO产生IL-1β和IL-18。 U1-snRNP抗体（Ab）或dsDNA/抗dsDNA Ab免疫复合物（snRNP IC或dsDNA IC，也称为狼疮IC 指两者）通过NLRP 3炎性体活化，其被细胞因子巨噬细胞 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， 在红斑狼疮中，炎症和坏死通路被激活，相互作用并协同促进炎症， 分子水平与促成独特的临床表现。因此，我们将测试狼疮 IC激活MO中的热解和坏死通路，具有促进炎症和组织的协同界面 损伤，并且这些通路的激活在狼疮中改变，从而导致临床病理表现。 该提案的目标是解决这一假设：1）目标1。阐明了这一机制及其意义 的激活和接口的pyroptic和necroptic分子在狼疮; 2）目的2。阐明“功能” 在狼疮患者中增强焦亡和坏死性凋亡介导的炎症的单核细胞改变;和 3)目标3.巨噬细胞移动抑制因子在狼疮炎症中的作用 调节着自燃和坏死的分子。我们的研究将为了解狼疮提供高度信息 发病机制以及开发评估和治疗狼疮患者的新方法。

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.