Cytokines as Biologic Adjuvants

研究正在进行中，以更好地确定外源性细胞因子在疫苗设计和开发中的作用。对于这些和其他正在进行的研究，已经开发了几种转基因（Tg）小鼠品系用于疫苗治疗肿瘤模型。这些包括在与人类中表达的位点相似的位点表达CEA或MUC-1作为自身抗原的Tg小鼠，以及发展自发性肿瘤的两种Tg小鼠品系。最近已经开发了双Tg小鼠品系，其中自发性肿瘤出现，其表达CEA或MUC-1作为自身抗原和在肿瘤组织中。临床前和临床研究现已证明GM-CSF通过募集树突状细胞在疫苗治疗中的作用。现在已经开发了表达GM-CSF作为转基因的重组禽痘病毒。当作为单次注射给药时，这些载体最近已显示出提高了排出注射部位的区域淋巴结中APC（包括树突细胞）的百分比和绝对数量。研究表明，这种反应的幅度和持续时间都远大于每天注射四次重组GM-CSF蛋白所达到的效果。最近的研究表明，表达CEA的重组禽痘病毒与表达GM-CSF的重组禽痘病毒的共施用显著增强CEA特异性免疫，在荷瘤CEA Tg小鼠中伴随免疫应答。正在进行研究，以使用新的转基因肿瘤模型来更好地定义新的疫苗策略。研究旨在确定：（a）长期给予膳食塞来昔布（Celebrex）（一种强效非甾体抗炎药，靶向环氧合酶-2（考克斯-2））是否会对宿主免疫力产生负面影响;以及（B）塞来昔布B可与基于痘病毒的疫苗联用，以影响自发性腺瘤性结肠息肉病小鼠肿瘤模型中的肿瘤负荷。喂食塞来昔布补充饲料的小鼠出现嗜酸性粒细胞增多，血浆前列腺素E（2）水平降低，脾脏T细胞中考克斯-2 mRNA表达水平降低。脾T、B和自然杀伤细胞对广泛基础和抗原特异性刺激的反应在这些小鼠以及考克斯-2敲除小鼠中大部分没有变化。当表达人癌胚抗原（CEA）基因的转基因小鼠（CEA转基因）与携带Apc（Delta 850）基因突变的小鼠（多发性肠肿瘤小鼠）交配时，后代（CEA转基因/多发性肠肿瘤）自发地发展出过表达CEA和考克斯-2的多发性肠肿瘤。从30日龄开始，给予多样化的初免/加强重组CEA-痘病毒为基础的疫苗方案或塞来昔布（1000 ppm）补充饮食，肠道肿瘤的数量分别减少了54%和65%。将CEA疫苗与塞来昔布补充饮食相结合，可将肿瘤负荷降低95%，并显着改善总体长期生存率。在没有任何针对CEA表达组织或其他正常组织的自身免疫证据的情况下，实现了肿瘤缩小和总生存率提高。塞来昔布用于治疗人类家族性腺瘤性息肉病，并且基于CEA的疫苗具有良好的耐受性，并且能够在早期临床研究中引发抗CEA宿主免疫应答。结果表明，重组痘病毒疫苗与塞来昔布是相容的，这种联合免疫化疗的方法可能不仅在家族性腺瘤性息肉病患者中产生额外的抗肿瘤治疗获益，而且可能在考克斯-2过表达与癌前病变进展为瘤形成相关的其他预防性环境中产生额外的抗肿瘤治疗获益。

Studies are ongoing to better define the role of exogenous cytokines in vaccine design and development. For these and other ongoing studies, several transgenic (Tg) mouse strains have been developed for vaccine therapy tumor models. These include Tg mice that express either CEA or MUC-1 as self-antigens at sites similar to those expressed in humans, and two Tg mouse strains that develop spontaneous tumors. Double Tg mouse strains have recently been developed in which spontaneous tumors arise that express either CEA or MUC-1 as self-antigen and in tumor tissue. Preclinical and clinical studies have now demonstrated the role of GM-CSF in vaccine therapy by recruitment of dendritic cells. Recombinant avipox viruses have now been developed that express GM-CSF as a transgene. When administered as a single injection, these vectors have recently been shown to enhance both the percentage and absolute number of APC (including dendritic cells) in the regional lymph nodes that drain the injection site. Both the magnitude and duration of this response was shown to be far greater than that achieved with the administration of four daily injections of recombinant GM-CSF protein. Recent studies have shown that the co-administration of recombinant avipox virus expressing CEA with recombinant avipox virus expressing GM-CSF significantly enhanced CEA-specific immunity, with an accompanying immunotherapeutic response in tumor-bearing CEA Tg mice. Studies are ongoing to use the new transgenic tumor models to better define novel vaccine strategies. Studies were designed to determine whether: (a) chronic administration of dietary celecoxib (Celebrex), a potent nonsteroidal anti-inflammatory drug, which targets the cyclooxygenase-2 (COX-2) enzyme, negatively impacts host immunity; and (b) celecoxib can be coupled with a poxvirus-based vaccine to impact tumor burden in a murine tumor model of spontaneous adenomatous polyposis coli. Naive mice fed the celecoxib-supplemented diets developed eosinophilia with lowered plasma prostaglandin E(2) levels and reduced COX-2 mRNA expression levels in their splenic T cells. Responses of splenic T, B, and natural killer cells to broad-based and antigen-specific stimuli were, for the most part, unchanged in those mice as well as COX-2 knockout mice. When transgenic mice that express the human carcinoembryonic antigen (CEA) gene (CEA transgenic) were bred with mice bearing a mutation in the Apc(Delta850) gene (multiple intestinal neoplasia mice), the progeny (CEA transgenic/multiple intestinal neoplasia) spontaneously develop multiple intestinal neoplasms that overexpress CEA and COX-2. Beginning at 30 days of age, the administration of a diversified prime/boost recombinant CEA-poxvirus-based vaccine regimen or celecoxib (1000 ppm)-supplemented diet reduced the number of intestinal neoplasms by 54% and 65%, respectively. Combining the CEA-based vaccine with the celecoxib-supplemented diet reduced tumor burden by 95% and significantly improved overall long-term survival. Both tumor reduction and improved overall survival were achieved without any evidence of autoimmunity directed at CEA-expressing or other normal tissues. Celecoxib is prescribed for the treatment of familial adenomatous polyposis in humans, and the CEA-based vaccines have been well tolerated and capable of eliciting anti-CEA host immune responses in early clinical studies. The results suggest that the administration of a recombinant poxvirus-based vaccine is compatible with celecoxib, and this combined chemoimmuno-based approach might lead to an additive therapeutic antitumor benefit not only in patients diagnosed with familial adenomatous polyposis but, perhaps, in other preventive settings in which COX-2 overexpression is associated with progression from premalignancy to neoplasia.