Assembly of ordered DNA-curli fibril complexes during Salmonella biofilm formation correlates with strengths of the type I interferon and autoimmune responses.
Assembly of ordered DNA-curli fibril complexes during Salmonella biofilm formation correlates with strengths of the type I interferon and autoimmune responses.
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DOI：
10.1371/journal.ppat.1010742
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发表时间：
2022-08
期刊：
影响因子：
6.7
通讯作者：
中科院分区：
文献类型：
--
作者：
人类淀粉样蛋白的沉积与复杂的人类疾病，如阿尔茨海默氏症和帕金森症有关。淀粉样蛋白也由细菌产生。细菌淀粉样卷曲蛋白存在于共生和致病性肠道细菌生物膜的细胞外基质中，与细胞外DNA形成复合物，宿主免疫系统对这些复合物的识别可能引发自身免疫反应。在这里，我们分离了在生物膜发育过程中形成的早期中间、中间和成熟卷曲原纤维，并研究了每种原纤维的结构和致病特性。早期中间聚集体比中间和成熟卷曲原纤维小，圆二色性、色氨酸和硫黄素T分析证实，随着卷曲构象的成熟，β -片二级结构的建立。中间和成熟卷曲原纤维比早期中间原纤维具有更强的体外免疫刺激作用。中间体curli对不依赖toll样受体2的巨噬细胞具有细胞毒性。成熟卷曲原纤维的DNA含量最高，诱导巨噬细胞中Isg15的表达和TNFα的产生水平最高。在小鼠中，成熟的卷毛原纤维诱导最高水平的抗双链DNA自身抗体。自身免疫易感性NZBWxF/1小鼠的自身抗体水平高于野生型C57BL/6小鼠。慢性暴露于所有形式的curli可导致自身免疫易感小鼠关节显著的组织病理学改变和滑膜增生；成熟的卷发是最有害的。综上所述，在生物膜形成过程中产生的curli原纤维可引起致病性自身免疫反应，当curli复合物含有较高水平的DNA时，这种反应在具有自身免疫倾向的小鼠中更强。卷曲淀粉样蛋白是沙门氏菌和大肠杆菌等肠道细菌生物膜的细胞外成分。在生物膜发育过程中，curli与细胞外DNA结合形成复合物，刺激免疫系统。利用互补技术，我们发现卷曲淀粉样蛋白在生物膜的发育过程中经历了物理和致病特性的变化，从早期中间和中间到成熟的卷曲原纤维聚合。虽然所有三种卷曲构象都激活了TLR2，但它们结合了不同数量的DNA，这些DNA与淀粉样蛋白的复杂性和它们诱导I型ifn和促炎细胞因子的能力呈正相关，并加速了自身免疫易感性小鼠抗dsdna自身抗体的发生。同步加速器x射线衍射结果表明，DNA是由卷曲单体的β片基序组织成一个空间周期性晶格，可以放大免疫激活。中间curli复合物是唯一在巨噬细胞中显示出独立于TLR2的细胞毒性的形式，它们诱导更高水平的IL-1b，一种参与细胞死亡的细胞因子。在易发生自身免疫的小鼠中，中间和成熟的curli/DNA也可诱导关节炎症。总的来说，卷曲-DNA复合物通过生物膜发育的成熟刺激了受DNA含量影响的不同免疫反应，并促进了小鼠的自身免疫特征。
Deposition of human amyloids is associated with complex human diseases such as Alzheimer’s and Parkinson’s. Amyloid proteins are also produced by bacteria. The bacterial amyloid curli, found in the extracellular matrix of both commensal and pathogenic enteric bacterial biofilms, forms complexes with extracellular DNA, and recognition of these complexes by the host immune system may initiate an autoimmune response. Here, we isolated early intermediate, intermediate, and mature curli fibrils that form throughout the biofilm development and investigated the structural and pathogenic properties of each. Early intermediate aggregates were smaller than intermediate and mature curli fibrils, and circular dichroism, tryptophan, and thioflavin T analyses confirmed the establishment of a beta-sheet secondary structure as the curli conformations matured. Intermediate and mature curli fibrils were more immune stimulatory than early intermediate fibrils in vitro. The intermediate curli was cytotoxic to macrophages independent of Toll-like receptor 2. Mature curli fibrils had the highest DNA content and induced the highest levels of Isg15 expression and TNFα production in macrophages. In mice, mature curli fibrils induced the highest levels of anti-double-stranded DNA autoantibodies. The levels of autoantibodies were higher in autoimmune-prone NZBWxF/1 mice than wild-type C57BL/6 mice. Chronic exposure to all curli forms led to significant histopathological changes and synovial proliferation in the joints of autoimmune-prone mice; mature curli was the most detrimental. In conclusion, curli fibrils, generated during biofilm formation, cause pathogenic autoimmune responses that are stronger when curli complexes contain higher levels of DNA and in mice predisposed to autoimmunity. Amyloid curli is an extracellular component of the biofilms of enteric bacteria like Salmonella and E. coli. During biofilm development, curli binds to extracellular DNA to form complexes that stimulate the immune system. Using complimentary techniques, we discovered that curli amyloids undergo changes in their physical and pathogenic properties throughout the development of the biofilm, polymerizing from early intermediate and intermediate to mature curli fibrils. While all three curli conformations activated TLR2, they bound different amounts of DNA that positively correlate with the complexity of the amyloids and their ability to induce type I IFNs and pro-inflammatory cytokines, and accelerate the onset of anti-dsDNA autoantibodies in autoimmune-prone mice. Synchrotron x-ray diffraction results suggest that DNA is organized by the beta sheet motif of curli monomers into a spatially periodic lattice that can amplify immune activation. Intermediate curli complexes were the only form that also showed cytotoxicity in macrophages independent of TLR2 and they induced higher levels of IL-1b, a cytokine involved in cell death. In mice prone to autoimmunity, the intermediate and mature curli/DNA induced also joint inflammation. Overall, the maturation of curli-DNA complexes through biofilm development stimulated distinct immune responses influenced by DNA content and promoted autoimmune features in mice.
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影响因子：
5.3
作者：
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通讯作者：
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影响因子：
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影响因子：
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影响因子：
5.6
作者：
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Cegelski, Lynette
影响因子：
5.6
作者：
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Gazit, E