基于MAPK/NF-κB和PI3K/Akt/NF-κB信号通路的海洋多肽CSP免疫调节机制研究

Immunity is defined as the ability of an organism to defend against disease by identifying and eliminating harmful substances or organisms. The functions of immune system can be adversely affected by many factors including stress, unhealthy life-style practices, pathogens and so on. However, side effects associated with allopathic drugs along with their high cost have enforced the need for searching alternative drugs with least or no side effects. Moreover, most immunomodulatory pharmaceuticals are not suitable for chronic or preventive use. So, the search for efficient and non-toxic immunomodulators has become a hot spot in the field of immunomodulatory research. CSP (RVAPEEHPVEGRYLV) is a polypeptide compound from marine protein hydrolysates and it has the significant ability to activate RAW264.7 macrophages in vitro. It shows that CSP may play an immunomodulatory role through toll-like receptor 4 related MAPK/NF-κB and PI3K/AKT/NF-κB signaling pathway. In this project, the MAPK/NF-κB and PI3K/AKT/NF-κB signaling pathway was used to reveal the mechanism action of CSP on immune regulation activity in the RAW264.7 macrophage model and cyclophosphamide induced immunosuppressed mouse model, respectively.

免疫系统作为机体抵御外界侵害的天然屏障，可以识别并消灭病毒、细菌等病原体，防止严重的感染和疾病。生活压力与不良生活习惯及病原体皆可导致机体免疫力下降而引发各种疾病。传统药物价格昂贵且对机体有一定的毒副作用，不适合于慢性或预防性的使用。因此，寻找高效、无毒性的免疫调节剂成为免疫调节研究领域的热点。海洋多肽CSP（RVAPEEHPVEGRYLV）是一种具有显著免疫调节活性的多肽类化合物，前期细胞模型研究表明其具有显著激活小鼠RAW264.7巨噬细胞的能力，CSP可能通过TLR4相关的MAPK/NF-κB和PI3K/AKT/NF-κB信号通路发挥免疫调节作用。本项目拟以小鼠RAW264.7巨噬细胞模型和环磷酰胺致免疫抑制小鼠模型，利用MAPK/NF-κB和PI3K/AKT/NF-κB信号通路从体内外水平揭示海洋多肽CSP发挥免疫调节活性的作用机制。

寻找高效、无毒性的免疫调节剂为免疫调节研究领域的热点。海洋多肽CSP（RVAPEEHPVEGRYLV）是一种具有显著免疫调节活性的多肽类化合物。本项目以小鼠RAW264.7巨噬细胞模型和环磷酰胺致免疫抑制小鼠模型，利用MAPK/NF-κB和PI3K/AKT/NF-κB信号通路从体内外水平揭示海洋多肽CSP发挥免疫调节活性的作用机制。体外RAW264.7细胞实验表明，经CSP作用后RAW264.7细胞的吞噬作用、NO和细胞因子分泌量（TNF-α、IL-1β和IL-6）明显增强。经CSP处理后，NF-κB通路中IKKα、IKKβ、NF-κB p65、NF-κB p50蛋白表达量均显著增加，IκBα蛋白含量显著下降；PI3K/Akt通路中PI3K及Akt蛋白磷酸化水平均升高；MAPK通路中p38、ERK、JNK蛋白磷酸化被激活，且效果显著。NF-κB抑制剂、PI3K抑制剂、MAPK抑制剂对CSP激活各通路蛋白的结果显示，经抑制剂预处理之后，CSP诱导的各通路蛋白浓度下降或上升。体内动物实验结果表明，CSP能缓解免疫抑制小鼠体重下降、脾脏和胸腺萎缩，增加脾脏指数和胸腺指数。同时增加血清中IL-1β、IL-6和TNF-α等细胞因子的含量。另外小鼠腹腔巨噬细胞的增殖能力、吞噬能力均有所上升；CSP对小鼠脾淋巴细胞体外增殖能力也有所提高。经CSP处理后小鼠脾脏中NF-κB通路的IKKα、IKKβ、NF-κB p65、NF-κB p50蛋白表达量均显著增加，IκBα蛋白含量显著下降；PI3K/Akt通路中PI3K及Akt蛋白磷酸化水平均升高；MAPK通路中p38、ERK、JNK蛋白磷酸化被激活，且效果显著。体内外实验表明CSP可通过MAPK/NF-κB和PI3K/Akt/NF-κB信号通路发挥免疫调节作用，本项目为后续开发CSP为免疫调节剂或免疫佐剂提供了重要的理论依据。

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