局部施用辛伐他汀抗生物膜及内植物感染的作用及其机制

Infections associated with orthopedic implants cause increased morbidity and significant healthcare cost.
Implant-related infections are typically caused by microorganisms growing in a hydrated matrix of their own synthesis, known as biofilms. Biofilms develop preferentially on inert surfaces and, thus, occur commonly on medical devices. Bacterial cells in biofilms can withstand host immune responses, and they are much less susceptible to antibiotics than their nonattached individual planktonic counterparts. For this reason, biofilm infections are difficult to truly eliminate and, typically, show recurring symptoms, even after cycles of antibiotic therapy. .In our previous animal studies, we found that local application of simvastatin promotes osteogenesis and angiogenesis; and our in vitro studies show that simvastatin can inhibit bacterial growth, inhibit bacterial biofilm formation and even destroy established biofilm while the molecular mechanism is not clear yet. Some studies reported that lipid synthesis is closely related with biofilm formation and statins can destroy functional membrane microdomains and improve antibiotic sensitivity by affecting lipid synthesis..Thus, we hypothesize that local application of simvastatin can affect lipid synthesis and functions as an anti-biofilm agent for implant-related infection. This study can be divided into three parts: ①to investigate the effect and mechanism of anti-biofilm of simvastatin in vitro; ②to develop a K-wire simvastatin coating, and observe whether the coating could inhibit biofilm formation and prevent from implant-association infection in animal model; ③to observe whether simvastatin could destroy the established biofilm when simvastatinn thermosensitive hydrogels are injected intraosseously and improve antibiotic sensitivity when combined with systemic antibiotic treatment of infection. This study will provide a new strategy and method for the prevention and treatment of implant-association infection, and also provide the basis for the “old drug, new tricks” of simvastatin to solve the problems of implant infection and bacterial resistance, which is of great clinical significance and research value.

内植物感染是骨科手术灾难性的并发症。微生物被胞外聚合物包裹形成的生物膜是内植物感染和抗生素耐药的主要原因。我们在前期动物实验中发现，局部施用辛伐他汀促进成骨、成血管；体外实验发现，辛伐他汀抑制细菌生长、抗生物膜形成并破坏成熟的生物膜，但机制不明。有研究发现脂质合成与生物膜形成密切相关；他汀干扰脂质合成，破坏功能性膜结构域，提高抗生素敏感性。我们推测，局部施用辛伐他汀抑制脂质合成、抗生物膜并防治内植物感染。本课题拟①体外研究辛伐他汀抗生物膜形成、破坏成熟生物膜的效果及其机制；②制备辛伐他汀涂层内植物，在体内观察其能否抑制生物膜的形成并预防内植物感染；③骨内注射辛伐他汀温敏性水凝胶联合系统应用抗生素，观察辛伐他汀能否破坏生物膜、增加抗生素敏感性。研究不仅为内植物感染的防治提供新的治疗思路和方法，还将为“老药新用”辛伐他汀解决内植物感染和细菌耐药提供依据，具有重要的临床意义和研究价值。

背景：内植物相关感染是骨科手术严重的并发症，治疗极其困难，给患者和社会带来沉重负担，是目前临床亟需解决的难题。内植物表面细菌生物膜的形成是感染和抗生素耐药的主要原因。研发同时具有抗菌性和良好生物相容性的内植物是目前的研究难点。.主要研究内容：①辛伐他汀体外对表皮葡萄球菌和金黄色葡萄球菌抗菌抗生物膜作用；②构建内植物表面辛伐他汀羟基磷灰石涂层，表征分析，研究体外对金葡菌的抗生物膜作用和生物相容性；③利用金葡菌构建大鼠股骨内植物相关感染模型，研究辛伐他汀羟基磷灰石涂层内植物的抗生物膜、预防内植物感染及促成骨作用。.重要结果：①辛伐他汀对表皮葡萄球菌和金黄色葡萄球菌ATCC 25923的最小抑菌浓度均为64μg/ml。辛伐他汀在体外有抑制两种菌株细菌生长、抑制生物膜形成，破坏已成熟生物膜的作用。②通过电化学沉积方法成功构建了辛伐他汀羟基磷灰石涂层修饰的Ti6Al4V内植物，与对照组相比，辛伐他汀羟基磷灰石涂层内植物的接触角显著降低，粗糙度显著增大。涂层中的药物在体外可有效释出达14天。③辛伐他汀羟基磷灰石涂层既能抑制金黄色葡萄球菌生物膜的形成，也能促进大鼠骨髓间充质干细胞的黏附、增殖和成骨分化。④体内实验，与对照组相比，辛伐他汀羟基磷灰石涂层使得大鼠外周血白细胞数量、TNF-α、IL-6水平显著降低，股骨远端骨溶解、骨膜反应较轻，X线评分低。该涂层抑制内植物表面细菌生物膜形成，降低外周血TRAcP-5b水平，提高BALP和OPN水平，大鼠股骨局部BV/TV、骨矿沉积率、内植物最大轴向拔出力显著增加，内植物局部骨整合改善。 .科学意义：揭示了辛伐他汀作为内植物药物涂层的抗菌、促成骨的多效性作用及其机制，为拓展他汀类化合物“老药新用”在内植物相关感染的应用提供了新策略，相关专利已受理，实质审查过程中。研究为骨科内植物抗菌涂层开发提供了理论依据，具有很高的临床应用潜力。