Role of macrophage polarization and PD/PD-L1/2 expression for the progression of leukoplakia to oral squamous cell carcinomas

超过60%的口腔鳞状细胞癌（OSCC）起源于口腔白斑（OLP）。口腔扁平苔藓组织学异常程度与恶变风险之间无可靠的相关性。局部免疫反应状况（免疫与耐受）可决定OLP向浸润性癌的转化。虽然免疫系统对口腔鳞状细胞癌进展的影响已经显示，但其对恶性转化过程的贡献尚未阐明。实体瘤中的局部免疫状况由肿瘤相关巨噬细胞的极化（M1对M2）决定。在这种情况下，M1极化的巨噬细胞诱导针对肿瘤细胞的免疫应答，而M2巨噬细胞与免疫耐受和肿瘤进展相关。在口腔鳞状细胞癌中，M2巨噬细胞参与了肿瘤的进展和转移扩散，免疫耐受是由抑制性信号通路介导的，即所谓的免疫检查点。除了肿瘤细胞，特别是巨噬细胞可以激活这样的信号通路。PD/PDL通路（PD：程序性细胞死亡，PDL：PD配体）是这些免疫检查点之一，其参与实体肿瘤（如OSCC）的免疫逃逸机制。先前在实体恶性肿瘤中使用检查点抑制剂的治疗研究显示了任何其他二线治疗方案都没有达到的临床成功。尽管通过检查点对免疫系统的生理调节在很大程度上仍然是难以捉摸的，但还是取得了这些令人鼓舞的结果。特别是，关于免疫检查点在前体病变恶性转化过程中的作用的数据缺失。拟议的项目旨在回答这个问题，如果OLP在未来转化为浸润性癌症已经显示出恶性转化之前的免疫耐受状态。这种免疫耐受可能通过巨噬细胞极化向M2的转移和PD/PDL信号传导的活化增加来观察。使用免疫组织化学和定量RT PCR，它应该被测试，如果一个集体的50个OLP转化为口腔鳞状细胞癌在5年的时间间隔内显示出向M2极化的巨噬细胞和/或PD 1受体和配体PDL 1/PDL 2的过度表达的转变相比，50个OLP没有显示出恶性转化在5年的时间窗口。作为对照组，使用50个健康口腔粘膜样品和50个对应于OLP的OSCC。如果在观察期间在OLP转化中可以显示向增加的巨噬细胞M2极化和/或PD/PDL过度活化的转变，则这将是癌症前体病变中已经存在免疫耐受的证据。这可以作为预测OLP恶性转化为OSCC的风险的标志物，并可以激励在OSCC的早期阶段或前驱病变中使用免疫调节治疗概念。

More than 60% of all oral squamous cell carcinomas (OSCC) derive from oral leukoplakia (OLP). There is no dependable correlation between the histological degree of dysplasia of OLP and the risk of malign transformation. The local immunological response situation (immunity vs. tolerance) could determine the transformation of OLP to invasive carcinomas. While an influence of the immune system on the progression of OSCC is already shown, its contribution on the process of malign transformation is not yet elucidated. The local immunological situation in solid tumors is determined by the polarization (M1 vs. M2) of tumor associated macrophages. In this context, M1 polarized macrophages induce immune response against tumor cells, while M2 macrophages are associated with immune tolerance and tumor progression. In OSCC, the involvement of M2 macrophages on tumor progression and metastatic spread is already shown.Immune tolerance is mediated by inhibitory signaling pathways, so called immune checkpoints. Besides tumor cells, especially macrophages can activate such signaling pathways. The PD/PDL pathway (PD: programmed cell death, PDL: PD Ligand) is one of these immunologic checkpoints, that is involved in the immune escape mechanism of solid tumors like the OSCC.The previous therapy studies with checkpoint inhibitors in solid malignancies showed a clinical success that was not reached by any other second line treatment regime. These encouraging results were achieved in spite of the fact that the physiologic regulation of the immune system by checkpoints is still elusive for the most part. Particularly, data regarding the role of immune checkpoints in the process of malign transformation of precursor lesions are missing.The proposed project aims to answer the question if OLP that transform to invasive cancers in the future already show a state of immune tolerance prior to malign transformation. This immune tolerance might be seen by a shift of macrophage polarization towards M2 and an increased activation of PD/PDL signaling. Using immunohistochemistry and quantitative RT PCR it should be tested, if a collective of 50 OLP that transformed to OSCC during a time interval of 5 years showed a shift towards M2 polarized macrophages and/or an overexpression of the PD1 receptor and the ligands PDL1/PDL2 compared to 50 OLP that showed no malign transformation in the 5 year time window. As control group 50 samples of healthy oral mucosa and 50 OSCC corresponding to the OLP are used.If a shift towards increased M2 polarization of macrophages and/or a PD/PDL overactivation can be shown in the OLPs transforming during the observation period, it would be an evidence of immune tolerance already present in cancer precursor lesions. This could serve as marker predicting the risk of malign transformation of OLP to OSCC and could motivate the use of immune modulatory therapy concepts already in early stages or precursor lesions of OSCC.