Biofilm growth increases phosphorylcholine content and decreases potency of nontypeable Haemophilus influenzae endotoxins
Biofilm growth increases phosphorylcholine content and decreases potency of nontypeable Haemophilus influenzae endotoxins
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DOI：
10.1128/iai.74.3.1828-1836.2006
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发表时间：
2006-03-01
影响因子：
3.1
通讯作者：
Swords, WE
中科院分区：
文献类型：
--
作者：
West-Barnette, S;Rockel, A;Swords, WE
不可分型流感嗜血杆菌（NTHI）是一种常见的呼吸道感染和条件致病菌。NTHI通常通过宿主先天防御包含在气道内，所述宿主先天防御包括通过Toll样受体4（TLR4）识别细菌内毒素。NTHI产生脂寡糖（LOS）内毒素，其缺乏聚合O侧链，可能含有宿主糖脂。我们最近发现NTHI生物膜含有唾液酸化LOS糖型的变体，这些变体对生物膜形成至关重要。在这项研究中，我们表明，NTHI形成上皮细胞层上的生物膜。共聚焦分析显示，唾液酸化的变体分布在整个生物膜，而表达磷酸胆碱（PCo）的变体被发现在生物膜内。与该观察结果一致，从NTHI生物膜纯化的LOS的PCho含量与来自非渗透培养物的LOS相比增加。假设所观察到的内毒素组成的变化可能影响生物活性，我们比较了从生物膜和增殖培养物中纯化的NTHI LOS的炎症反应。我们的研究结果表明，内毒素从生物膜诱导较弱的宿主先天性反应。虽然我们观察到唾液酸化对LOS生物活性的最小影响，但与PCho取代相关的生物活性显著降低。因此，我们得出结论，生物膜生长增加了NTHI群体中PCo（+）变体的比例，导致LOS生物活性的净下降。因此，除了有充分证据证明的耐药表型外，我们的数据还表明NTHI细菌的生物膜群落包含引起较弱宿主反应的变体。
Nontypeable Haemophilus influenzae (NTHI) is a common respiratory commensal and opportunistic pathogen. NTHI is normally contained within the airways by host innate defenses that include recognition of bacterial endotoxins by Toll-like receptor 4 (TLR4). NTHI produces lipooligosaccharide (LOS) endotoxins which lack polymeric O side chains and which may contain host glycolipids. We recently showed that NTHI biofilms contain variants with sialylated LOS glycoforms that are essential to biofilm formation. In this study, we show that NTHI forms biofilms on epithelial cell layers. Confocal analysis revealed that sialylated variants were distributed throughout the biofilm, while variants expressing phosphorylcholine (PCho) were found within the biofilm. Consistent with this observation, PCho content of LOS purified from NTHI biofilms was increased compared to LOS from planktonic cultures. Hypothesizing that the observed changes in endotoxin composition could affect bioactivity, we compared inflammatory responses to NTHI LOS purified from biofilm and planktonic cultures. Our results show that endotoxins from biofilms induced weaker host innate responses. While we observed a minimal effect of sialylation on LOS bioactivity, there was a significant decrease in bioactivity associated with PCho substitutions. We thus conclude that biofilm growth increases the proportion of PCho(+) variants in an NTHI population, resulting in a net decrease in LOS bioactivity. Thus, in addition to their well-documented resistance phenotypes, our data show that biofilm communities of NTHI bacteria contain variants that evoke less potent host responses.