O-Acetylation of Capsular Polysialic Acid Enables Escherichia coli K1 Escaping from Siglec-Mediated Innate Immunity and Lysosomal Degradation of E. coli-Containing Vacuoles in Macrophage-Like Cells.
O-Acetylation of Capsular Polysialic Acid Enables Escherichia coli K1 Escaping from Siglec-Mediated Innate Immunity and Lysosomal Degradation of E. coli-Containing Vacuoles in Macrophage-Like Cells.
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DOI：
10.1128/spectrum.00399-21
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发表时间：
2021-12-22
影响因子：
3.7
通讯作者：
Jin C
中科院分区：
文献类型：
--
作者：
Yang J;Ma W;Wu Y;Zhou H;Song S;Cao Y;Wang C;Liu X;Ren J;Duan J;Pei Z;Jin C
大肠杆菌 K1 会导致人类新生儿菌血症和脑膜炎。 K1 胶囊是一种 α2,8 连接的聚唾液酸 (PSA) 均聚物，是其重要的毒力因子。 PSA通常被O-乙酰基部分修饰。众所周知，O-乙酰化会改变 PSA 的抗原性，但其对大肠杆菌 K1 与宿主细胞之间相互作用的影响尚不清楚。在本研究中，通过大肠杆菌K1亲本菌株的传代获得了相变体，其表达具有44％O-乙酰化的荚膜，而亲本菌株的荚膜只有3％。与亲本菌株相比，变异菌株对巨噬细胞样细胞的粘附和侵袭显着减少。此外，我们发现 PSA 的 O-乙酰化增强了对含有大肠杆菌的液泡 (ECV) 运输的调节，使它们能够避免与这些细胞中的溶酶体融合。有趣的是，通过使用石英晶体微天平，我们证明从亲本菌株中纯化的PSA与人唾液酸结合免疫球蛋白样凝集素（Siglecs）相互作用，包括Siglec-5、Siglec-7、Siglec-11和Siglec-14。然而，来自变体的 O-乙酰化 PSA 相互作用要少得多，并且还抑制 Siglec 介导的促炎细胞因子的产生。针对 Siglec-11 和 Siglec-14 的单克隆抗体显着阻断了亲本菌株与人巨噬细胞样细胞的粘附。此外，与亲本菌株相比，变异菌株导致新生小鼠菌血症增加和致死率更高。这些数据阐明，K1 胶囊的 O-乙酰化使大肠杆菌能够逃避 Siglec 介导的先天免疫和溶酶体降解；因此，这是大肠杆菌K1用来调节其毒力的策略。重要性 大肠杆菌 K1 是新生儿脑膜炎的主要原因。尽管采用抗生素治疗，这种疾病的死亡率和发病率仍然很高。脑膜炎预防和治疗进展的一个主要限制是对其发病机制的不完全了解。大肠杆菌 K1 被 PSA 包围，观察到其 O-乙酰基修饰具有高频变化。在这里，我们深入研究了 PSA 中 O-乙酰化在宿主与病原体相互作用的每个阶段的功能。我们发现高水平的 O-乙酰化显着干扰 Siglec 介导的细菌对巨噬细胞样细胞的粘附，并减弱促炎反应。此外，PSA 的 O-乙酰化调节 ECV 的运输，防止它们与溶酶体融合，使它们能够逃避细胞内溶菌酶的降解。阐明胶囊的微妙修饰如何增强细菌对宿主先天免疫的防御能力，将使未来开发出有效的抗大肠杆菌 K1 感染的药物或疫苗成为可能。
Escherichia coli K1 causes bacteremia and meningitis in human neonates. The K1 capsule, an α2,8-linked polysialic acid (PSA) homopolymer, is its essential virulence factor. PSA is usually partially modified by O-acetyl groups. It is known that O-acetylation alters the antigenicity of PSA, but its impact on the interactions between E. coli K1 and host cells is unclear. In this study, a phase variant was obtained by passage of E. coli K1 parent strain, which expressed a capsule with 44% O-acetylation whereas the capsule of the parent strain has only 3%. The variant strain showed significantly reduced adherence and invasion to macrophage-like cells in comparison to the parent strain. Furthermore, we found that O-acetylation of PSA enhanced the modulation of trafficking of E. coli-containing vacuoles (ECV), enabling them to avoid fusing with lysosomes in these cells. Intriguingly, by using quartz crystal microbalance, we demonstrated that the PSA purified from the parent strain interacted with human sialic acid-binding immunoglobulin-like lectins (Siglecs), including Siglec-5, Siglec-7, Siglec-11, and Siglec-14. However, O-acetylated PSA from the variant interacted much less and also suppressed the production of Siglec-mediated proinflammatory cytokines. The adherence of the parent strain to human macrophage-like cells was significantly blocked by monoclonal antibodies against Siglec-11 and Siglec-14. Furthermore, the variant strain caused increased bacteremia and higher lethality in neonatal mice compared to the parent strain. These data elucidate that O-acetylation of K1 capsule enables E. coli to escape from Siglec-mediated innate immunity and lysosomal degradation; therefore, it is a strategy used by E. coli K1 to regulate its virulence. IMPORTANCE Escherichia coli K1 is a leading cause of neonatal meningitis. The mortality and morbidity of this disease remain significantly high despite antibiotic therapy. One major limitation on advances in prevention and therapy for meningitis is an incomplete understanding of its pathogenesis. E. coli K1 is surrounded by PSA, which is observed to have high-frequency variation of O-acetyl modification. Here, we present an in-depth study of the function of O-acetylation in PSA at each stage of host-pathogen interaction. We found that a high level of O-acetylation significantly interfered with Siglec-mediated bacterial adherence to macrophage-like cells, and blunted the proinflammatory response. Furthermore, the O-acetylation of PSA modulated the trafficking of ECVs to prevent them from fusing with lysosomes, enabling them to escape degradation by lysozymes within these cells. Elucidating how subtle modification of the capsule enhances bacterial defenses against host innate immunity will enable the future development of effective drugs or vaccines against infection by E. coli K1.
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影响因子：
11.1
作者：
Karlstetter M;Kopatz J;Aslanidis A;Shahraz A;Caramoy A;Linnartz-Gerlach B;Lin Y;Lückoff A;Fauser S;Düker K;Claude J;Wang Y;Ackermann J;Schmidt T;Hornung V;Skerka C;Langmann T;Neumann H
通讯作者：
Neumann H
影响因子：
3.4
作者：
Kim, KJ;Elliott, SJ;Kim, KS
通讯作者：
Kim, KS
影响因子：
3.9
作者：
Avril, T.;Attrill, H.;Crocker, P. R.
通讯作者：
Crocker, P. R.
DOI：
10.1073/pnas.120163297
发表时间：
2000-06-06
影响因子：
11.1
作者：
Datsenko, KA;Wanner, BL
通讯作者：
Wanner, BL
影响因子：
4.8
作者：
Angata, T;Kerr, SC;Varki, A
通讯作者：
Varki, A