年青小鼠血清Exosomes改善免疫衰老和慢性炎症的机制研究

In a series of experiments that the blood of a young mouse circulates through the murine equivalent of an old geezer, Loffredo and colleagues have shown that startling physiological changes occur. Many of the trademark depredations of old age-withering muscles; stiff, oversized hearts; cognitive decline; and even the fraying of the myelin coating that insulates nerve fibers-are slowed, repaired, or even reversed. They think that growth differentiation factor 11(GDF11) appears to rejuvenate the architecture of the heart, the vasculature of the brain, and the bulk of skeletal muscle, but there are many controversy on the role of GDF11, and we admit the existence of controversy. It is unknown about heterochronic parabiosis rejuvenate effect and mechanism on immunity system and its upstream signal transduction pathway. Exosomes contain both cytosolic and transmembrane proteins, and mRNA and microRNA and can be viewed as a way of intercellular communication without the need for cell-cell contact, thus conveying a potential biologic activity to more distant targets. Depending on their origin and composition, the exosomes have either immuostimulatory or immunosuppressive properties.. We isolate exosomes from young mice serum and injected into old mice, we found that the exosomes rejuvenate the age-related thymus senescence and gene expression, age-related abnormality of thymic microstructure. Young serum exosomes recover the aged-related deterioration of T cell function in the periphery, and reduce the aged-related chronic inflammation. Next we will confirm the function of YMSE on improving the immune senescence and reducing chronic inflammation in aged mice. After find the mechanism of rejuvenation, we will investigate the spectrum of specific RNAs expressed in young mice’s and old mice’s serum exosomes and found the RNA which rejuvenate the immune senescence and reduce the aged-related Chronic Inflammation. We try to find the mechanism of RNA rejuvenated age-related thymus senescence and got the ideas of how to explore the aged mechanism of other organ.

Loffredo将老年鼠与年青鼠血液循环交联后老化组织器官结构与机能改善并认为这些改善与GDF11有关，但有研究质疑GDF11的作用。本课题组也发现GDF11在老年鼠血清中是增高的，而且无联体手术对免疫衰老的报道。Exosomes参与机体重要生命活动，包括免疫调节。本课题组给予老年鼠YMSE后，检测显示其能改善胸腺基质微环境，增强萎缩胸腺功能，减轻慢性炎症反应。本课题组拟用不同方法明确YMSE改善老年鼠免疫衰老及减轻慢性炎症的功能，探索YMSE改善老年鼠免疫衰老及减轻慢性炎症的成分及机制，通过高通量测序对YMSE和OMSE进行大规模差异筛选，数据分析后结合qPCR及Northern blot验证该转录本在免疫细胞中的差异分布，通过“loss of function” 或“ gain of function” 明确具体RNA在免疫衰老及炎症因子分泌中的作用，并研究该分子作用信号通路或靶基因。

衰老导致慢性炎症，增加了与年龄相关的疾病的风险，如心脑血管疾病。因此，开发能够减轻发炎，逆转衰老的策略作为帮助干预与年龄有关的疾病的手段非常重要。联体手术使老年鼠退行性变改善的实验早有报道，但其机制在此之前并不清楚。.本课题组研究表明，退行性变的逆转和改善应该与年青血液中的特异组分有关，而年青血液中的Exosomes极有可能在其中扮演关键角色。课题组提取年青小鼠血清内的Exosomes（young mice serum Exosomes, YMSE），静脉注射老年鼠检测发现，与对照组（PBS)相比, 老年鼠萎缩胸腺明显增大，胸腺指数明显增加，胸腺细胞增殖分化相关基因FoxN1与ΔNP63的表达明显增高，提示YMSE能改善老年鼠胸腺萎缩程度。进一步检测显示YMSE能改善胸腺基质微环境，增强萎缩胸腺功能，减少萎缩胸腺慢性炎症反应，老年胸腺中负选择相关分子的表达升高。老年小鼠的慢性自身免疫易感性和炎性特征减少。除了减少外周血的炎症水平，还减少了神经系统中的炎症因子水平（已发表）。通过高通量测序对YMSE和OMSE (Old Mice Serum Exosomes)所含转录本（mRNA、miRNA或LncRNA）进行大规模差异筛选， 我们比较了年青鼠和老龄鼠TEC miRNA表达谱的变化，并明确鉴定并验证了至少一种miRNA miR-125a-5p在老年胸腺中增加了。应用miR-125a-5p模拟物能够抑制293T细胞系中的FoxN1 3’UTR荧光素酶活性，并抑制鼠TEC Z210细胞中FoxN1的表达（已发表）。.本课题还比较了健康老年人和健康年轻人的血清外泌体mRNA水平，高通量测序结果显示老年人血浆中的FGF10 mRNA表达量显著高于年轻人。qPCR检测年轻组小鼠和衰老组小鼠肺、脾组织中的FGF10 mRNA水平，显示衰老组小鼠组织中FGF10 mRNA水平明显增高；但Western boltting检测结果发现年轻小鼠组织中FGF10蛋白水平却高于老年组；过表达FGF10后发现能减少衰老基因表达水平；同样，给予FGF10重组蛋白，也能减少衰老细胞衰老水平。均提示FGF10蛋白能逆转衰老状态(尚未发表)。.本课题通过筛选YMSE中改善老年鼠免疫衰老及减轻慢性炎症的作用因子，为逆转免疫衰老，治疗免疫衰老相关疾病提供可能靶点，也为研究抗衰老及抗退行性变提供思路。