TLR4低毒激动剂MPLA对肠道辐射损伤的防治作用及机制研究

Intestinal tissue is highly sensitive to ionizing radiation. There is still no specific treatment for the serious intestine radiation damage or intestinal radiation sickness, and the mortality of wounded is as high as 100%. So it is an urgent problem to be solved in the field of radiology. It has been found that activation of Toll-like receptors (TLRs) can promote the proliferation of intestinal epithelial cells and intestine repair after radiation, which possess significant radiation preventive effect. Especially TLR4 plays an important role in this respect. However, the toxicity of TLR4 traditional agonist LPS hampered its practical application, it is urgent to carry out the exploration of attenuated synergies. Our preliminary study ha found that low toxicity of TLR4 agonist MPLA plays a clear role in the protection of animal intestinal radiation injury. Therefore, TLR4 has brought new hope for the prevention and treatment of intestinal radiation injury. On this basis, we will investigate the protective effects of MPLA on intestinal radiation damage from the perspective of animal, cell and molecular levels by gene knockout and CRISPR-Cas9 assays. And explore the preventive molecular mechanism of MPLA from multiple ways including TLR4 downstream genes, regulation of Wnt signaling pathway and screening the radiation protective targets of MPLA. This study is aimed to explore effective strategy for the prevention and treatment of intestinal radiation damage.

肠道组织对电离辐射高度敏感，目前国内外对肠道严重辐射损伤或肠型放射病仍无特异性治疗手段,伤员死亡率百分之百,成为放射医学领域亟待攻克的难题。研究发现激活Toll样受体(TLRs)可促进受照肠上皮细胞增殖和肠道修复，具有显著的辐射防治作用，尤其TLR4在这方面扮演着重要角色。但TLR4传统激动剂LPS的毒性严重制约了其实际应用,亟需开展减毒增效探索。我们前期研究发现MPLA毒性很低,其激活TLR4对动物肠道损伤有很好的防治作用,为实际应用TLR4防治肠道辐射损伤带来新的希望。本项目将在此基础上,拟用基因敲除、CRISPR-Cas9技术等研究手段,从动物、细胞和分子水平多层次探明MPLA对肠道辐射损伤防治作用规律；并从TLR4下游基因、Wnt信号通路的调节作用、MPLA发挥辐射防护作用靶点的筛选等多个途径，探索MPLA防治作用的分子机制。旨在为肠道辐射损伤的防治探索更有效的救治新途径、新技术。

肠道组织对电离辐射高度敏感，目前国内外对肠道严重辐射损伤或肠型放射病仍无特异性治疗手段，伤员死亡率百分之百，成为放射医学领域亟待攻克的难题。研究发现激活Toll样受体(TLRs)可促进受照肠上皮细胞增殖和肠道修复，具有显著的辐射防治作用，尤其TLR4在这方面扮演着重要角色。但TLR4传统激动剂LPS的毒性严重制约了其实际应用,亟需开展减毒增效探索。我们前期研究发现MPLA毒性很低，其激活TLR4对动物肠道损伤有很好的防治作用，为实际应用TLR4防治肠道辐射损伤带来新的希望。本项目将在此基础上，拟从细胞、类器官、动物和分子水平多层次探明MPLA对肠道辐射损伤防治作用规律；并从TLR4下游基因、Wnt信号通路的调节作用、MPLA发挥辐射防护作用靶点的筛选等多个途径探索MPLA防治作用的分子机制。具体取得如下结果：①辐射损伤后给予MPLA刺激能促进小肠类器官及小肠隐窝干细胞的再生。②MPLA能促进辐射损伤后小肠干细胞的再生并且抑制辐射导致的小肠隐窝细胞坏死、凋亡以及活性分子的降解。③MPLA刺激后能显著激活Wnt和Notch信号通路，并上调c-Myc、MSl2、SOX9和YAPl蛋白，该激活和上调作用依赖TLR4受体。④对MPLA刺激后小肠隐窝细胞中相关分子的相互作用模式进行了探索，明确了小肠隐窝细胞增殖和再生过程中MyD88与Trif对相关蛋白的募集存在不同的模式。该研究将为肠道辐射损伤的防治提供更有效的救治新途径、新技术。