Bacterial amyloids break tolerance in lupus

 描述(申请人提供)：系统性红斑狼疮(SLE)是一种多因素自身免疫性疾病，感染被认为在其中起致病作用，最近的研究表明共生菌群也起作用，但分子罪魁祸首仍有待发现。细菌生物膜是一种多细胞细菌群落，广泛存在于人体微生物群落中，在病原体慢性感染的形成过程中起着重要作用。目前还没有研究表明生物膜中存在的分子复合体是否有助于系统性红斑狼疮的进展。我们最近发现，细菌和真核DNA被整合到卷曲纤维、沙门氏菌和大肠杆菌生物膜中存在的功能性细菌淀粉样蛋白中。我们发现，生物膜中的Curli/DNA复合体激活了传统的树突状细胞，导致产生促炎细胞因子，包括在SLE中致病的I型干扰素。体内注射CURLI/DNA复合体可激活DC和B细胞，提示CURLI是一类新的复合危险信号。给予Curli/DNA复合体可在易患狼疮的NZBxW/F1小鼠和野生型小鼠中触发自身抗体的产生，这表明来自生物膜的Curli/DNA复合体是SLE发病机制中的新参与者。为了将我们的发现转化到床边，我们开发了一种新的ELISA来测量抗卷曲抗体，并发现SLE患者在临床发作期间有高水平的抗卷曲抗体。我们建议探索Curli/DNA是否影响狼疮的两个主要致病步骤：1)PDCs刺激干扰素信号和2)自身反应性B细胞的激活，方法是研究Curli直接激活B细胞的能力，可能通过TLRs作为佐剂来诱导抗原特异性反应，并打破耐受以刺激狼疮自身抗体谱。共生大肠杆菌感染只在细菌表达CurLi时才能诱导自身抗体的初步结果，为研究Curli作为狼疮发病机制中感染的主要分子刺激提供了有力的理论基础。我们将测试Curli是否是感染加速狼疮发病和引发红斑狼疮的促自身免疫效应的主要介体。这些研究将使用小鼠模型。为了建立与人类疾病的强大致病联系，并在我们的初步结果的支持下，我们还将研究人类样本，通过测量抗卷曲抗体的血清效价，确定SLE患者是否比健康对照组更多地暴露在卷曲中，并与疾病活动和红斑的发生相关。这些研究可能提供一种新的闪光生物标志物，并建议将生物膜和细菌淀粉样蛋白作为狼疮的新治疗工具。

 DESCRIPTION (provided by applicant): Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease, in which infections are considered to play a pathogenic role, and more recent work is suggesting a role for the commensal flora as well, but the molecular culprits are still to be discovered. Bacterial biofilms are multicellular bacterial communities, abundant in the human microbiome, and also important in the establishment of chronic infection by pathogens. No study has yet addressed whether molecular complexes present in biofilms contribute to SLE progression. We have recently found that bacterial and also eukaryotic DNA is incorporated into curli fibers, functional bacterial amyloids present in Salmonella and E. coli biofilms. We found that curli/DNA complexes in biofilms activate conventional dendritic cells leading to production of pro-inflammatory cytokines, including Type I interferons, which are pathogenic in SLE. In vivo injection of curli/DNA complexes activated DCs and B cells, indicating that curli are a new class of composite danger signals. Administration of curli/DNA complexes triggered autoantibodies production in lupus-prone NZBxW/F1 mice and also in wild type mice, suggesting curli/DNA complexes from biofilms as novel players in SLE pathogenesis. To translate our finding to the bedside, we developed a new ELISA to measure anti-curli antibodies and found that SLE patients have high levels of anti-curli antibodies during clinical flares. We propose to explore if curli/DNA affect two major pathogenic steps in lupus: 1) the stimulation of IFN Signature by pDCs and 2) the activation of autoreactive B cells, by studying curli ability to directly activate B cells, possibly through TLRs, to act as an adjuvant to induce Ag-specific responses and break tolerance to stimulate a lupus autoAb profile. The Preliminary result that infection by a commensal E. coli induces autoAbs only when bacteria expressed curli, provides a strong rationale for studying curli as the dominant molecular stimulus by infections in lupus pathogenesis. We will test if curli is the main mediator of the pro-autoimmune effects of infections in accelerating lupus onset and inducing flares. These studies will use murine models. To establish a powerful pathogenic link with the human disease, and supported by our Preliminary results, we will also study human samples to determine whether SLE patients are exposed to curli more than healthy controls by measuring serum titers of anti-curli antibodies, in correlation with disease activity and occurrence of flare. These studies may provide a novel biomarker of flares and suggest targeting biofilms and bacterial amyloids as new therapeutic tools in lupus.