Lockhart Joey S, Buret Andre G, Ceri Howard, Storey Douglas G, Anderson Stefanie J, Morck Douglas W
Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada; Biofilm Research Group, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada; Biofilm Research Group, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
Anaerobe. 2017 Oct;47:157-164. doi: 10.1016/j.anaerobe.2017.05.008. Epub 2017 May 17.
Biofilms composed of anaerobic bacteria can result in persistent infections and chronic inflammation. Host immune cells have difficulties clearing biofilm-related infections and this can result in tissue damage. Neutrophils are a vital component of the innate immune system and help clear biofilms. The comparative neutrophilic response to biofilms versus planktonic bacteria remains incompletely understood, particularly in the context of mixed infections. The objective of this study was to generate mixed species anaerobic bacterial biofilms composed of two opportunistic pathogens, Fusobacterium necrophorum and Porphyromonas levii, and evaluate neutrophil responses to extracellular fractions from both biofilms and planktonic cell co-cultures of the same bacteria. Purified bovine neutrophils exposed to culture supernatants from mixed species planktonic bacteria showed elevated oxidative activity compared to neutrophils exposed to biofilms composed of the same bacteria. Bacterial lipopolysaccharide plays a significant role in the stimulation of neutrophils; biofilms produced substantially more lipopolysaccharide than planktonic bacteria under these experimental conditions. Removal of lipopolysaccharide significantly reduced neutrophil oxidative response to culture supernatants of planktonic bacteria. Oxidative responses to LPS-removed biofilm supernatants and LPS-removed planktonic cell supernatants were similar. The limited neutrophil response to biofilm bacteria observed in this study supports the reduced ability of the innate immune system to eradicate biofilm-associated infections. Lipopolysaccharide is likely important in neutrophil response; however, the presence of other extracellular, immune modifying molecules in the bacterial media also appears to be important in altering neutrophil function.
由厌氧菌组成的生物膜可导致持续性感染和慢性炎症。宿主免疫细胞难以清除与生物膜相关的感染，这可能导致组织损伤。中性粒细胞是先天免疫系统的重要组成部分，有助于清除生物膜。对生物膜与浮游细菌的中性粒细胞反应比较仍未完全了解，特别是在混合感染的情况下。本研究的目的是生成由两种机会性病原体——坏死梭杆菌和利氏卟啉单胞菌组成的混合菌种厌氧细菌生物膜，并评估中性粒细胞对来自相同细菌的生物膜和浮游细胞共培养物的细胞外组分的反应。与暴露于由相同细菌组成的生物膜的中性粒细胞相比，暴露于混合菌种浮游细菌培养上清液的纯化牛中性粒细胞显示出更高的氧化活性。细菌脂多糖在刺激中性粒细胞方面起重要作用；在这些实验条件下，生物膜产生的脂多糖比浮游细菌多得多。去除脂多糖显著降低了中性粒细胞对浮游细菌培养上清液的氧化反应。对去除脂多糖的生物膜上清液和去除脂多糖的浮游细胞上清液的氧化反应相似。本研究中观察到的中性粒细胞对生物膜细菌的有限反应支持了先天免疫系统根除与生物膜相关感染能力的降低。脂多糖可能在中性粒细胞反应中很重要；然而，细菌培养基中其他细胞外免疫调节分子的存在似乎在改变中性粒细胞功能方面也很重要。
