Departments of Otolaryngology-Head and Neck Surgery, Oncology and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
Clin Cancer Res. 2011 Jun 15;17(12):3984-92. doi: 10.1158/1078-0432.CCR-10-3262. Epub 2011 May 4.
Because toll-like receptor (TLR) agonists have been well characterized as dendritic cell (DC) activators, we hypothesized that the admixture of TLR4 agonist into a cellular vector could improve the antitumor response in vivo.
Granulocyte macrophage colony stimulating factor secreting whole cell tumor cell vector (GVAX) was formulated with lipopolysaccharide (LPS), a TLR4 agonist, and its intratumoral therapeutic efficacy was tested in three different murine models. We utilized immunohistochemistry, fluorescence-activated cell sorting, enzyme-linked immunosorbent spot (ELISPOT), and in vivo CTL analysis to assess both local innate immune responses within the tumor tissue as well as the downstream generation of antitumor T-cell responses.
Intratumoral treatment of LPS-absorbed GVAX showed efficacy in improving an antitumor response in vivo in comparison with GVAX alone. Improved antitumor efficacy of this novel admixture was not present in TLR4 signaling impaired mice. In the CT26 model, 40% to 60% of the mice showed regression of the transplanted tumor. When rechallenged with CT26 tumor cells, these mice proved to be immunized against the tumor. Tumors treated with TLR4 agonist-absorbed GVAX showed increased infiltrating CD4 and CD8 T cells as well as increased numbers of CD86(+) cells in the tumor tissue. Draining lymph nodes from the treated mice had enhanced number of activated CD86(+), MHCII(+), and CD80(+) DCs in comparison with GVAX alone and mock-treated groups. ELISPOT assay and in vivo CTL assay showed increased numbers of CTLs specific for the AH1 tumor antigen in mice treated with LPS-absorbed GVAX.
TLR4 on antigen-presenting cells in the tumor microenvironment may be targeted by using cell-based vectors for improved antitumor response in vivo.
由于 Toll 样受体（TLR）激动剂已被很好地描述为树突状细胞（DC）激活剂，我们假设将 TLR4 激动剂混入细胞载体中可以改善体内的抗肿瘤反应。
粒细胞巨噬细胞集落刺激因子分泌的全细胞肿瘤细胞载体（GVAX）与脂多糖（LPS）混合，LPS 是一种 TLR4 激动剂，其在三种不同的小鼠模型中的肿瘤内治疗效果进行了测试。我们利用免疫组织化学、荧光激活细胞分选、酶联免疫斑点（ELISPOT）和体内 CTL 分析来评估肿瘤组织内局部先天免疫反应以及抗肿瘤 T 细胞反应的下游产生。
与单独 GVAX 相比，肿瘤内给予 LPS 吸收的 GVAX 治疗可改善体内抗肿瘤反应。在 TLR4 信号受损的小鼠中，这种新型混合物的抗肿瘤功效并不存在。在 CT26 模型中，40%至 60%的小鼠移植瘤发生消退。当再次用 CT26 肿瘤细胞攻击时，这些小鼠被证明对肿瘤具有免疫性。用 TLR4 激动剂吸收的 GVAX 治疗的肿瘤显示出肿瘤组织中浸润性 CD4 和 CD8 T 细胞增加，以及 CD86(+)细胞数量增加。与单独 GVAX 治疗和模拟治疗组相比，来自治疗小鼠的引流淋巴结中具有更多激活的 CD86(+)、MHCII(+)和 CD80(+)DC。ELISPOT 测定和体内 CTL 测定显示，用 LPS 吸收的 GVAX 治疗的小鼠中针对 AH1 肿瘤抗原的 CTL 数量增加。
肿瘤微环境中的抗原呈递细胞上的 TLR4 可能成为通过使用基于细胞的载体来改善体内抗肿瘤反应的靶点。
