Extracellular DNA (eDNA) plays an important role in both the aggregation of bacteria and in the interaction of the resulting biofilms with polymorphonuclear leukocytes (PMNs) during an inflammatory response. Here, transmission electron and confocal scanning laser microscopy were used to examine the interaction between biofilms of Pseudomonas aeruginosa and PMNs in a murine implant model and in lung tissue from chronically infected cystic fibrosis patients. PNA FISH, DNA staining, labeling of PMN DNA with a thymidine analogue and immunohistochemistry were applied to localize bacteria, eDNA, PMN-derived eDNA, PMN-derived histone H3 (H3), neutrophil elastase (NE) and citrullinated H3 (citH3). Host-derived eDNA was observed surrounding bacterial biofilms but not within the biofilms. H3 localized to the lining of biofilms while NE was found throughout biofilms. CitH3, a marker for neutrophil extracellular traps (NETs) was detected only sporadically indicating that most host-derived eDNA in vivo was not a result of NETosis. Together these observations show that, in these in vivo biofilm infections with P. aeruginosa, the majority of eDNA is found external to the biofilm and derives from the host.

中文翻译：

---

体内细菌生物膜感染中细胞外DNA的起源。

细胞外DNA（eDNA）在细菌聚集以及在炎症反应过程中所得生物膜与多形核白细胞（PMN）的相互作用中都起着重要作用。在这里，使用透射电子和共聚焦扫描激光显微镜检查铜绿假单胞菌生物膜之间的相互作用鼠感染模型和慢性感染的囊性纤维化患者肺组织中的PMN和PMN。将PNA FISH，DNA染色，用胸苷类似物标记PMN DNA并进行免疫组化以定位细菌，eDNA，PMN衍生的eDNA，PMN衍生的组蛋白H3（H3），中性粒细胞弹性蛋白酶（NE）和瓜氨酸化的H3（citH3）。在细菌生物膜周围观察到宿主来源的eDNA，但在生物膜内部未观察到。H3定位于生物膜的内衬，而NE遍布整个生物膜。CitH3是嗜中性粒细胞胞外陷阱（NETs）的标志物，仅偶发地检测到，表明体内大多数宿主衍生的eDNA并非NETosis的结果。这些观察结果共同表明，在这些体内铜绿假单胞菌感染的生物膜感染中，大多数eDNA被发现在生物膜的外部，并来源于宿主。