Coating of endotracheal tubes with sphingosine to prevent bacterial growth and ventilator-associated pneumonia

呼吸机相关性肺炎(VAP)是一个严重的临床问题，也是危重病人发病率和死亡率的重要原因。上呼吸道的细菌感染和这些管子上细菌生物膜的形成已被证明是一个重要的因素。本课题组首次发现，鞘氨醇是一种存在于大多数真核细胞膜中的鞘氨醇，在呼吸道上皮细胞中以高浓度存在，并通过阻止细菌入侵下呼吸道而在上呼吸道的先天免疫中发挥重要作用。我们已经开发了几种新的方法来在气管内管的表面涂覆鞘氨醇和植鞘氨醇，这是一种鞘氨醇类似物，模拟鞘氨醇在哺乳动物气管和支气管中的作用。有两种这样的方法，一种是用鞘氨醇或植鞘氨醇浸渍管，另一种是用神经鞘氨醇和植鞘氨醇结合的聚多巴胺涂覆管子。这两种方法获得了相似的结果；鞘氨醇或植鞘糖醇涂层可防止高达99%的铜绿假单胞菌、鲍曼不动杆菌和金黄色葡萄球菌的附着和生长。然而，尽管浸渍涂层后的神经鞘氨醇和植鞘氨醇在塑料管上的稳定性不够好，但采用聚多巴胺技术涂层非常稳定，但这种涂层显著降低了塑料管的柔韧性。我们现在的目标是(I)合成能够与聚氯乙烯(PVC)管共价结合而不改变其材料特性的鞘氨醇类似物，(Ii)测试这些新型涂层在体外各种生物流体中的杀菌性能和稳定性，(Iii)确定涂层的稳定性以及这些涂层导管在体内气管中的潜在毒性或不良影响，以及(Iv)在小鼠模型中，确定涂有鞘氨醇类似物的气管内管是否可以预防局部和全身细菌感染。

Ventilator-associated pneumonia (VAP) is a serious clinical problem and an important cause of morbidity and mortality in critically ill patients. Bacterial infections of the upper airway combined with the development of bacterial biofilm on those tubes has proven to be an important factor. Our group was the first to show that sphingosine, a sphingolipid present in most eukaryotic membranes, is present in high concentrations in the respiratory epithelium and plays an important role in the innate immunity of the upper respiratory tract by preventing bacterial invasion into the lower airways. We have developed several novel methods of coating the surface of endotracheal tubes with sphingosine and phytosphingosine, a sphingosine analog that mimics the role of sphingosine in the mammalian trachea and bronchi. Two such methods are dip-coating the tubes with sphingosine or phytosphingosine or coating them with polydopamine, to which sphingosine and phytosphingosine are bound. The two methods achieved comparable results; the sphingosine or phytosphingosine coating prevents as much as 99% of adherence and growth of Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus. However, although the stability of sphingosine and phytosphingosine on the plastic tube after dip coating was insufficient, the coating was very stable with the polydopamine technique, but this coating markedly reduced the flexibility of the tube. Thus, improved coating techniques with modified sphingosine derivatives that allow covalent and, thus, stable binding without changing the material properties of the plastic tube are required.We now aim (i) to synthesize sphingosine analogs that can covalently bind to polyvinyl chloride (PVC) tubes without changing their material properties, (ii) to test the bactericidal properties and the stability of these novel coatings in various biological fluids in vitro, (iii) to determine the stability of the coating and the potential toxicity or adverse effects of these coated catheters in the trachea in vivo, and (iv) to determine whether endotracheal tubes coated with sphingosine analogs prevent local and systemic bacterial infections in vivo in a mouse model.