脓毒症治疗的新策略：基于噬菌体展示与生物信息学的技术途径探索

Sepsis is a systemic inflammatory response syndrome caused by pathogen infections. Sepsis can further develop to septic shock, multiple organ failure (MOF), which is the prominent cause for the mortality of patients in intensive care units (ICU). Wide application of antibiotics in the clinical patients has brought about the overflow of drug resistance to infectious bacteria, thus increasing the difficulty of sepsis treatment. Various bacterium are involved in the pathogenesis of Sepsis, but different bacteria has different sensitivity to antibacterial drugs, organ distributions as well as other biological behaviors, which leads to different clinical manifestation and outcome of illness. So it is urgent to establish individualized medical strategy targeting a specific pathogen for the prevention and treatment of sepsis. We had successfully screened peptides specifically binding to lipopolysaccharide (LPS)-activated human umbilical vein endothelial cells (HUVECs), and set up a platform for bioinformatic analysis based on conservation of peptide motif sequence. Based on the work above, this project is proposed to reproduce the CLP sepsis model with BALB/c mice, and to screen the specific binding peptides for the pathogenic bacterium. The fusion protein of specific binding peptide with the enhanced green fluoresce protein (EGFP) will be prepared to trace pathogen’s distribution, multiplication and its damage to tissues. The specific binding peptides will be fused with an antimicrobial peptide by the gene cloning method, which is used to explore the technical scheme for bacterial killing by targeting the surface structure of pathogens, thus providing a novel strategy for individualized precision medicine of sepsis caused by infection of specific pathogens.

脓毒症是由感染引起的全身炎症反应综合征，其发展可导致脓毒性休克、多器官功能衰竭，一直是临床危重病患者的首要死因。抗生素在临床上普遍使用，造成细菌耐药泛滥，从而增加了脓毒症的治疗难度。脓毒症感染的病原菌多种多样，而不同病原菌对药物的敏感性、器官嗜性等生物学行为不同，由此带来了临床表现和预后的差异，迫切需要建立针对特定病原菌的个体化脓毒症防治策略。我们前期利用噬菌体展示技术成功淘选了LPS激活的人脐静脉血管内皮细胞特异性结合肽，并建立了基于多肽基序的生物信息学分析平台。本项目拟在上述工作基础上，复制小鼠CLP脓毒症模型，并针对分离的特定致病菌淘选特异性结合肽；利用特异性结合肽与绿色荧光蛋白的融合蛋白示踪致病菌在各组织器官的分布、繁殖情况及其对组织的损伤作用；并利用基因克隆方法获得特异性结合肽与抗菌肽的融合蛋白，以探索靶向性杀灭病原菌的技术方案，为针对感染病原菌的个体化脓毒症精准医疗提供新策略。

病原菌感染是脓毒症的根本原因。有效的抑制或杀灭病原菌是脓毒症治疗的关键。虽然许多抗感染药物已被用于治疗脓毒症，但由于临床上缺乏特异性的细菌靶向递送系统，其应用受到严重限制。本研究的目的是开发一种针对病原菌的靶向抗感染多肽，以更好地治疗脓毒症。我们利用噬菌体展示技术、高通量测序和生物信息学技术，获得了一种能与脓毒症小鼠病原菌膜蛋白选择性结合的细菌靶向性多肽(VTK)。我们以该多肽为载体，将LL37导入病原菌，合成VTK-LL37，研究其靶向抗菌活性。结果表明，VTK-LL37的体外抑菌活性和生物被膜抑制率均优于LL37。VTK-LL37通过抑制细菌生长，降低HMGB1的表达，减轻体内重要脏器损伤，提高脓毒症小鼠的存活率。提示VTK-LL37对脓毒症的靶向杀灭作用优于LL37。VTK-LL37是一种有效的靶向细菌的抗感染递送系统，有望用于脓毒症治疗。本研究为靶向杀灭病原体提供了一种技术方案，为靶向杀灭病原菌提供了技术方案，为脓毒症的精准治疗提供了新的策略。

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