【作者】 严君；

【导师】 胡卓伟；

【作者基本信息】 北京协和医学院 ， 药理学， 2009， 博士

【摘要】 肿瘤是世界范围内严重危害人类健康的重大疾病,也是全球引起死亡的第二大杀手,肿瘤转移是引起死亡的最主要原因。随着人类逐步进入老龄化社会,肿瘤的危害将进一步加重,而目前仍没有有效的防治肿瘤的方法。这就迫切的需要我们探索肿瘤发生发展的机理,开发新的有效的治疗手段。最近的研究显示,慢性炎症和纤维化在肿瘤发生、发展和转移中发挥了重要的促进作用。慢性炎症产生大量的炎性介质,这些炎性介质既可以直接作用于正常细胞发生突变,引起肿瘤发生,也可以通过调节肿瘤局部微环境,促进肿瘤增殖,诱导血管新生和组织重构,产生免疫耐受,共同促进肿瘤的发生、发展及转移。同时,肿瘤细胞也可以通过释放炎性介质,维持慢性炎症反应状态,以利于自身的发展。纤维化的产生亦可诱导或加速实质细胞突变,促进肿瘤转移。TLR是介导内外源性因素引起炎症反应的最重要的受体,在调节机体炎症应答和免疫应答中发挥重要的作用,目前TLR的激动剂和抑制剂广泛用于开发成疫苗佐剂治疗肿瘤和其它疾病。因此,我们联合使用TLR的激动剂或抑制剂,以慢性炎症和纤维化为靶点,探索抑制肿瘤转移的免疫治疗方法。我们采用EC-LPS与CpG两种强的免疫刺激剂／促炎剂联合使用,观察预防给药和治疗给药对黑色素瘤实验性肺转移模型的作用。结果显示,预防性使用EC-LPS与CpG,抗肿瘤免疫细胞(CTL和M1)和细胞因子(IL-12和IFN-γ)显著增多,促进产生抗肿瘤的急性炎症反应,减少抑制性免疫细胞(M2、Treg和pDC)、细胞因子(IL-10和TGF-β)和趋化因子的产生,抑制肿瘤相关慢性炎症的产生,但对肿瘤间质的纤维化没有明显影响,产生预防肿瘤转移的作用；而治疗性使用EC-LPS与CβG也可增加M1的数量,但不能减少甚至少量增加M2和pDC细胞的数量,显示治疗给药时肿瘤细胞对EC-LPS与CpG促进炎症的作用进行了编辑,产生了有利于自身的慢性炎症。因而,我们进行了下一部分试验,采用促炎剂CpG与慢性炎症抑制剂anti-TLR2抗体联合使用,治疗肿瘤转移。结果显示,二者联合使用,将机体的促癌的慢性炎症状态转变为抑癌的急性炎症状态,抑制了肿瘤间质的纤维化,产生了协同作用,极显著的抑制了肿瘤转移,显示了慢性炎症抑制剂与促炎剂联合使用,产生协同促进抗癌的急性炎症的作用,对于治疗肿瘤转移具有重要的意义。我们的研究显示,机体炎症反应系统是非常复杂而精确调控的。采用促炎剂进行肿瘤治疗时其给药时机非常重要,否则不能产生治疗效果甚至反而起促进肿瘤的作用。而联合使用慢性炎症抑制剂,是非常重要的保证免疫治疗成功的环节,对于临床治疗肿瘤具有重要的指导意义。更多还原

【Abstract】 Cancer is serious hazard to public health, and is one of the worldwide leading killers. The majority of cancer mortality is due to disseminated disease rather than the primary tumor. TLR9 agonist CpG ODN was shown to have an encouraging anti-tumor activity in a number of experimental models by stimulating an anti-tumor immunity. However, the results from phase III clinical trails of CpG ODN are disappointing. What accounts for the failure of TLR9 agonists acting as anti-tumor therapeutics? Recent studies indicate that chronic inflammation and the activation of extracellular matrix play a critical role in cancer metastasis. Components of the tumor microenvironment, such as tumor cells, stromal cells and infiltrated inflammatory/immune cells generated an intratumoral chronic inflammatory state by aberrant expression or activation of some proinflammatory molecules, such as cytokines, chemokines and COX2, and a distinct network of intracellar signaling molecular including upstream kinases and transcription factors facilitate tumor progression, such as NF-κB and STAT3. All these mediators suppressed the anti-tumor immune response and accounted for the failure of clinical immunotherapy. Inflammatory response is triggered by the receptors of innate immune system, such as Toll-like receptors (TLRs). Kim et al and our own studies indicate that TLR2 activity is crucial in tumor metastasis via mediating chronic inflammation and activation of fibrosis. Thus, we tested if an innovative therapeutic strategy in which TLR9 agonist plus an anti-TLR2 antibody produced a better efficacy in the attenuation of metastasis than a strategy combination of two immunostimulators in an experimental metastasis model by i.v. injection B16F10 cells. We found that prophylactic administration of TLR4 agonist EC-LPS plus TLR9 agonist CpG ODN attenuated tumor metastasis but had no therapeutic efficacy because this combination was not potent sufficient to reverse the tumor cell-established immune tolerance. However, combining an anti-TLR2 antibody with CpG ODN therapeutically attenuated tumor metastasis in synergy compared with anti-TLR2 antibody or CpG ODN alone. Our studies suggest that timing for administering an immunotherapy is important but combining an immunostimulatory agent with an agent who can eliminate inhibitory chronic inflammation from tumor environment and attenuated fibrosis of the stroma is critical for obtaining an effective immunotherapeutic efficacy against tumor metastasis.更多还原