Epigenetic Regulation Alters Biofilm Architecture and Composition in Multiple Clinical Isolates of Nontypeable Haemophilus influenzae.
Epigenetic Regulation Alters Biofilm Architecture and Composition in Multiple Clinical Isolates of Nontypeable Haemophilus influenzae.
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DOI：
10.1128/mbio.01682-18
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发表时间：
2018-09-18
期刊：
影响因子：
6.4
通讯作者：
Bakaletz LO
中科院分区：
文献类型：
--
作者：
Brockman KL;Azzari PN;Branstool MT;Atack JM;Schulz BL;Jen FE;Jennings MP;Bakaletz LO
上呼吸道感染是孩子去急诊室的第一大原因，中耳炎（中耳感染）排在第三位。生物膜对包括中耳炎在内的细菌性呼吸道感染的慢性性质起着重要作用，并使这些疾病特别难以治疗。几种与粘膜相关的人类病原体利用一种称为相位变化或相位变量调节的快速适应机制来抵抗环境和宿主的免疫压力。在这项研究中，我们评估了相位变化在不可分型流感嗜血杆菌（NTHI）生物膜形成调控中的作用，NTHI导致许多呼吸道疾病。我们发现NTHI相位变化在特定疾病条件下调节生物膜结构和关键的生物膜基质成分。这项工作的发现对于设计针对NTHI感染的改进策略以及由于利用阶段变异的其他病原体引起的疾病具有重要意义。生物膜在许多人类病原体的定植、持久性和发病机制中起着关键作用。多种粘膜相关病原体已经进化出一种快速适应机制，称为阶段性，这有助于在细菌基因组中协调调节众多基因。这种表观遗传调控通过DNA甲基转移酶（Mod）的相位变化发生。不可分型流感嗜血杆菌（NTHI）的相位变化显著影响实验性中耳炎的严重程度，并调节几种疾病相关过程。然而，NTHI阶段变化在生物膜形成中的作用尚不清楚。本研究表明，多种NTHI临床分离株的阶段变化在疾病特异性微环境条件下调节体外生物膜的形成。在碱性条件下，相变调节的影响最大，这种碱性条件类似于疾病期间中耳发生的情况。在碱性条件下，表达ModA2甲基转移酶的NTHI菌株形成的生物膜比ModA2缺乏群体形成的生物膜具有更大的生物量和更少的结构差异。表达ModA2的NTHI菌株形成的生物膜也含有较少的细胞外DNA （eDNA）和显著较少的细胞外HU（一种对生物膜结构稳定性至关重要的DNA结合蛋白）。在多种疾病的实验模型中，稳定的生物膜结构对细菌的发病和持续至关重要。这些结果确定了相位变化在生物膜形成的调节中的作用，这是许多感染的慢性本质不可或缺的过程。了解相变在生物膜形成中的作用对这些慢性疾病的预防和治疗策略的发展至关重要。
Upper respiratory tract infections are the number one reason for a child to visit the emergency department, and otitis media (middle ear infection) ranks third overall. Biofilms contribute significantly to the chronic nature of bacterial respiratory tract infections, including otitis media, and make these diseases particularly difficult to treat. Several mucosa-associated human pathogens utilize a mechanism of rapid adaptation termed the phasevarion, or phase variable regulon, to resist environmental and host immune pressures. In this study, we assessed the role of the phasevarion in regulation of biofilm formation by nontypeable Haemophilus influenzae (NTHI), which causes numerous respiratory tract diseases. We found that the NTHI phasevarion regulates biofilm structure and critical biofilm matrix components under disease-specific conditions. The findings of this work could be significant in the design of improved strategies against NTHI infections, as well as diseases due to other pathogens that utilize a phasevarion. Biofilms play a critical role in the colonization, persistence, and pathogenesis of many human pathogens. Multiple mucosa-associated pathogens have evolved a mechanism of rapid adaptation, termed the phasevarion, which facilitates a coordinated regulation of numerous genes throughout the bacterial genome. This epigenetic regulation occurs via phase variation of a DNA methyltransferase, Mod. The phasevarion of nontypeable Haemophilus influenzae (NTHI) significantly affects the severity of experimental otitis media and regulates several disease-related processes. However, the role of the NTHI phasevarion in biofilm formation is unclear. The present study shows that the phasevarions of multiple NTHI clinical isolates regulate in vitro biofilm formation under disease-specific microenvironmental conditions. The impact of phasevarion regulation was greatest under alkaline conditions that mimic those known to occur in the middle ear during disease. Under alkaline conditions, NTHI strains that express the ModA2 methyltransferase formed biofilms with significantly greater biomass and less distinct architecture than those formed by a ModA2-deficient population. The biofilms formed by NTHI strains that express ModA2 also contained less extracellular DNA (eDNA) and significantly less extracellular HU, a DNABII DNA-binding protein critical for biofilm structural stability. Stable biofilm structure is critical for bacterial pathogenesis and persistence in multiple experimental models of disease. These results identify a role for the phasevarion in regulation of biofilm formation, a process integral to the chronic nature of many infections. Understanding the role of the phasevarion in biofilm formation is critical to the development of prevention and treatment strategies for these chronic diseases.