分析人類口腔鱗狀上皮細胞癌浸潤之調節性T細胞與Th17細胞間相互關係

Characterization of tumor infiltrating regulatory T cells and the interplay with Th17 cells in human oral squamous cell carcinoma

賴宛伶(Wan-Ling Lai)

指導教授 ： 賈景山

國立臺灣大學/醫學院/微生物學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.01166

摘要

口腔鱗狀上皮細胞癌(OSCC)在全世界屬於排名第六名的癌症，其治療後存活率仍然相當低。由調節性T細胞造成的免疫抑制被認為對口腔鱗狀上皮細胞癌的產生扮演重要角色，在近期研究中發現CD4+CD25highFoxp3+調節性T細胞可被區分成兩群表現型不同的細胞，分別為ICOS+Foxp3+調節性T細胞以及ICOS-Foxp3+調節性T細胞， ICOS+Foxp3+調節性T細胞被認為屬於表現IL-10以及少量mTGF-β，而ICOS-Foxp3+調節性T細胞只表現mTGF-β。在實驗室先前研究中已知口腔鱗狀上皮細胞癌的病患其腫瘤內浸潤淋巴細胞中CD4+CD25highFoxp3+調節性T細胞所佔的比例比病患血液中高出許多，此外先前研究也發現到病患浸潤腫瘤內調節性T細胞可依CD25、Foxp3表現量的差異在細分為不同亞群的調節性T細胞，並且表現出不同程度的細胞激素，在本研究中將探討口腔鱗狀上皮細胞癌腫瘤內浸潤淋巴細胞中的調節性T細胞是否也可利用ICOS表現差異來區分成不同表現型的調節性T細胞。除此之外，近期研究中，Th17 細胞在腫瘤中扮演的角色也廣泛的被探討當中，許多研究確實也發現Th17細胞與腫瘤生長息息相關，更有研究指出腫瘤中Th17細胞與調節性T細有重要的相互關係，然而究竟Th17細胞對腫瘤生長扮演甚麼角色以及與調節性T細胞之間的相互關係為何至今仍不清楚，本篇研究中發現腫瘤浸潤淋巴細胞中存在大量Th17細胞以及IL-17+Foxp3+細胞，這與腫瘤微環境中存在高量的IL-1β、IL-6、TGF-β等誘導Th17細胞產生的細胞激素結果一致。此外，研究中也發現不同於血液中研究的結過，在腫瘤內IL-17+Foxp3+細胞與Th17細胞的分佈具有非常高度相關性，而Th17細胞與調節性T細胞的分佈則形成負相關，這說明了確實Th17細胞與調節性T細胞間確實有著重要的相關性。為了進一步證實腫瘤細胞對於Th17細胞的產生有直接相關性，我們利用體外共同培養實驗證實了的確腫瘤細胞能誘導IL-17+Foxp3+細胞的產生。由於Th17細胞起出的研究被認為是與病原菌的清除相關，而口腔鱗狀上皮細胞癌已知時常會伴隨著細菌感染的發生，研究中也觀察到病患腫瘤組織中確實存在著細菌16S RNA，因此在口腔鱗狀上皮細胞癌腫瘤內發現的Th17細胞與細菌感染是否也具有相關性，在研究中也將進一步探討。

關鍵字

口腔鱗狀上皮細胞癌 ； 調節性T細胞 ； Th17細胞 ； 腫瘤浸潤淋巴細胞

並列摘要

Oral squamous-cell carcinoma (OSCC) was the sixth most common cancer worldwide with low survival rates after therapy. Immunosuppression mediated by CD4+CD25highFoxp3+ regulatory T (Treg) cells was a characteristic feature of OSCC. Recent studies have defined two subsets of FOXP3+ natural Treg cells by the expression of the costimulatory molecule ICOS and IL-10 or TGF-b. Our previous study revealed that proportion of CD4+CD25highFoxp3+ Treg cells in TIL were significantly enriched relative to that found in PBMC from OSCC patients. Moreover, there were different subsets of regulatory T cells infiltrated in OSCC. The specific aim was to identify and characterize the different subsets of Tregs in TIL based on ICOS expression. In addition, association of Tregs with the presence of Th17 cells was also investigated to confirm whether there was synergistic or antagonistic relationship between these cells in TIL of OSCC. Despite the important role of Th17 cells in the pathogenesis of many autoimmune diseases, their prevalence and the mechanisms by which they are generated and regulated in cancer remain unclear. A recent study found that the tumor-associated Th17 cells and Treg cells were synchronically increased following tumor development. The kinetic distribution of Treg cells and Th17 cells suggested their close relationship in the tumor. In this study, we reported that the high percentage of CD4+IL-17+ cells and IL-17+Foxp3+ cells in the tumor site, compared with the low percentage of CD4+IL-17+ cells and IL-17+Foxp3+ cells in PBMC from healthy donor and cancer patient. These finding consisted with the high level of IL-1β、IL-6、TGF-β presented in the tumor microenvironment. Moreover, this study also found the prevalence of IL-17+Foxp3+ cells and Th17 cells were high positive correlation, and the prevalence of Th17 cells and Foxp3 cells were high negative correlation in the tumor site. To further demonstrate the role of tumor cells in the induction of IL-17+Foxp3+ cells, the in vitro coculture system were performed. The results show coculture of PBMC with tumor cells could generate high percentage of Th17 cells and IL-17+Foxp3+ cells. It has been reported that viable bacteria presented within oral squamous cell carcinoma tissue. The correlation between Th17 cells generation and bacteria infection in OSCC needs further investigation.

並列關鍵字

oral squamous-cell carcinoma ； regulatory T cells ； Th17 cells ； tumor infiltraing lymphocytes

參考文獻

Ayyouba, M., Deknuydta, F., Raimbauda, I., Dousseta, C., Levequea, L., Bioleya, G. & Valmoria, D. (2009). Human memory FOXP3_ Tregs secrete IL-17 ex vivo and constitutively express the TH17 lineage-specific transcription factor RORγt. Proc Natl Acad Sci U S A 106: 8635–8640.

Berhanu, A., Huang, J., Watkins, S. C., Okada, H. & Storkus, W. J. (2007). Treatment-Enhanced CD4+Foxp3+ Glucocorticoid-Induced TNF Receptor Family RelatedHigh Regulatory Tumor-Infiltrating T Cells Limit the Effectiveness of Cytokine-Based Immunotherapy. J Immunol 178: 3400-3408.

Beriou, G., Costantino, C. M., Ashley, C. W., Yang, L., Kuchroo, V. K., Baecher-Allan, C. & Hafler, D. A. (2009). IL-17 producing human peripheral regulatory T cells retain suppressive function. Blood 30: 4240-4249.

Bettelli, E., Korn, T., Oukka M. & Kuchroo V. K. (2008). Induction and effector functions of TH17 cells. Nature Rev 453: 1051-1057.

Casares, N., Arribillaga, L., Sarobe, P., Dotor, J., Ascensio´n Lopez-Diaz de Cerio, Melero, I., Prieto, J., Borra´s-Cuesta, F. & Lasarte, J. J. (2003). CD4+/CD25+ regulatory cells inhibit activation of tumour-primed CD4+ T cells with IFN-γ-dependent antiangiogenic activity, as well as long-lasting tumour immunity elicited by peptide vaccination. J Immunol 171: 5931–5939.