The Antimicrobial Peptide Human Beta-Defensin 2 Inhibits Biofilm Production of Pseudomonas aeruginosa Without Compromising Metabolic Activity
The Antimicrobial Peptide Human Beta-Defensin 2 Inhibits Biofilm Production of Pseudomonas aeruginosa Without Compromising Metabolic Activity
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DOI：
10.3389/fimmu.2020.00805
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发表时间：
2020-05-08
影响因子：
7.3
通讯作者：
Porter, Edith
中科院分区：
文献类型：
--
作者：
Parducho, Kevin R.;Beadell, Brent;Porter, Edith
生物膜的产生是一个关键的毒力因子，它促进细菌在宿主表面的定植，并受到复杂途径的调节，包括群体感应，也控制色素的产生等。为了限制定植，上皮细胞作为第一道防线的一部分，利用包括防御素在内的多种抗菌肽（AMP）。孔形成是AMP杀菌活性的最佳研究机制。考虑到人β-防御素2（HBD 2）分泌到上皮表面以响应细菌和生物膜在微生物感染中的重要性，我们假设HBD 2具有生物膜抑制活性。我们评估了在存在和不存在HBD 2的情况下，与高度杀菌的HBD 3相比，产生绿脓杆菌的铜绿假单胞菌菌株的活力和生物膜形成。在纳摩尔浓度下，HBD 2-不依赖于其手性状态-显着降低生物膜形成，但不降低代谢活性，不像HBD 3，其降低生物膜和代谢活性的程度相同。在HBD 2处理的另一种革兰氏阴性细菌鲍曼不动杆菌中也观察到生物膜抑制和代谢活性维持之间的类似差异。没有证据表明HBD 2干扰生物膜生产的调节。生物膜相关基因的表达和另一种群体感应控制产物--绿脓菌素色素的细胞外积累在HBD 2处理的细菌和对照细菌之间没有显著差异，并且计算机模拟不支持HBD 2与群体感应分子的直接结合。然而，在HBD 2处理后，观察到外膜蛋白质谱的改变伴随着表面拓扑结构的变化，通过原子力显微镜记录。这表明HBD 2诱导结构变化，干扰生物膜前体转运到细胞外空间。总之，这些数据支持了一种新的机制，生物膜抑制纳摩尔浓度的HBD 2是独立的生物膜调节途径。
Biofilm production is a key virulence factor that facilitates bacterial colonization on host surfaces and is regulated by complex pathways, including quorum sensing, that also control pigment production, among others. To limit colonization, epithelial cells, as part of the first line of defense, utilize a variety of antimicrobial peptides (AMPs) including defensins. Pore formation is the best investigated mechanism for the bactericidal activity of AMPs. Considering the induction of human beta-defensin 2 (HBD2) secretion to the epithelial surface in response to bacteria and the importance of biofilm in microbial infection, we hypothesized that HBD2 has biofilm inhibitory activity. We assessed the viability and biofilm formation of a pyorubin-producing Pseudomonas aeruginosa strain in the presence and absence of HBD2 in comparison to the highly bactericidal HBD3. At nanomolar concentrations, HBD2 - independent of its chiral state - significantly reduced biofilm formation but not metabolic activity, unlike HBD3, which reduced biofilm and metabolic activity to the same degree. A similar discrepancy between biofilm inhibition and maintenance of metabolic activity was also observed in HBD2 treated Acinetobacter baumannii, another Gram-negative bacterium. There was no evidence for HBD2 interference with the regulation of biofilm production. The expression of biofilm-related genes and the extracellular accumulation of pyorubin pigment, another quorum sensing controlled product, did not differ significantly between HBD2 treated and control bacteria, and in silico modeling did not support direct binding of HBD2 to quorum sensing molecules. However, alterations in the outer membrane protein profile accompanied by surface topology changes, documented by atomic force microscopy, was observed after HBD2 treatment. This suggests that HBD2 induces structural changes that interfere with the transport of biofilm precursors into the extracellular space. Taken together, these data support a novel mechanism of biofilm inhibition by nanomolar concentrations of HBD2 that is independent of biofilm regulatory pathways.