正常人與口腔癌病患中CD8+ T細胞亞群對細菌或自體α-烯醇酶的反應及PD-1阻斷後的效果

Abstract

α-烯醇酶被認為是腫瘤相關的抗原，已知在不同類型的癌症病患中，皆有對抗α-烯醇酶的自體抗體和T細胞，但目前對於這些T細胞的特徵並不是很清楚。除此之外，對抗鏈球菌表面α-烯醇酶的抗體，可以對人類自體的α-烯醇酶作用，可能是造成自體反應的重要因素，然而這樣的情況是否同樣出現在T細胞上是未知的。為了回答這些問題，我們利用細菌及人類專屬的α-烯醇酶胜肽群，各別去刺激正常人及口腔癌病人的週邊血液單核細胞。我們發現正常人的T細胞，也能對人類專屬的α-烯醇酶胜肽群產生反應，雖然有反應的比例比口腔癌病人低。在口腔癌病患中，腫瘤浸潤T細胞對α-烯醇酶胜肽群的反應與週邊血液T細胞不盡相同。而在有反應的人之中，相較於正常人，口腔癌病患對細菌及人類α-烯醇酶有反應的T細胞比例比較高。這些對α-烯醇酶有反應的T細胞，可能是初始T細胞、中心記憶T細胞、效應記憶T細胞及末端分化效應T細胞。在效應記憶T細胞及末端分化效應T細胞之中，大部份對α-烯醇酶有反應的T細胞都表現CD127和PD-1。因此，我們進一步探討PD-1阻斷對這些T細胞的影響。對細菌α-烯醇酶有反應的T細胞，在PD-1阻斷後可能增加或減少，然而對人類α-烯醇酶有反應的T細胞，在PD-1阻斷後只會減少。我們的結果顯示正常人與口腔癌病患對細菌或人類α-烯醇酶的反應不同，PD-1阻斷對這些T細胞的效應也不同。

α-enolase has been known as a tumor-associated antigen, autoantibodies and T cells against α-enolase have been defined in several types of cancer patients. However, the characteristics of enolase-reactive T cells are poorly understood so far. Furthermore, it has been reported that antibodies target streptococcal surface enolase could react with human α-enolase, playing an important role in the initiation of auto-reactivity. However, whether TCR cross-reaction between bacterial and human enolase has not been verified. To address the questions, we used bacteria-specific and human-specific enolase peptides to stimulate peripheral blood mononuclear cells (PBMCs) of healthy donors and oral cancer patients. We reveal that healthy donors also respond to human enolase with lower proportion than oral cancer patients. In oral cancer patients, tumor-infiltrating lymphocytes (TILs) show different reactivity to enolase peptides from PBMCs. Among the responders, higher frequency of bacterial and human enolase-reactive CD8 T cells in oral cancer patients than healthy donors. Characterize the phenotype of enolase-reactive CD8 T cells, they may be naïve, central memory (TCM), effector memory (TEM), and terminally differentiated T cells (TEMRA). In TEM and TEMRA subsets, majority of enolase-reactive T cells are CD127+ and PD-1+. Therefore, We further explore the effects of PD-1 blockade on enolase-reactive T cells. Surprisingly, bacterial enolase-reactive T cells from different individuals show converse reactions to PD-1 blockade, while human enolase-reactive T cells among the responders only reduce the reactions after PD-1 blockade. Our results suggest the differential reactivities to bacterial or human enolase in healthy donors and oral cancer patients, and the different effects after PD-1 blockade on enolase-reactive CD8 T cells