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1.陆军军医大学(第三军医大学)大坪医院,消化内科,消化系统肿瘤精准防治重庆市重点实验室,重庆
2.陆军军医大学(第三军医大学)大坪医院,病理科,重庆
3.金凤实验室,重庆
4.南京大学医学院附属金陵医院(东部战区总医院)肿瘤科,江苏南京
马强,E-mail:blmaq@sina.com
王涛,E-mail:t26983@tmmu.edu.cn
收稿:2026-01-02,
修回:2026-01-26,
纸质出版:2026-03-30
移动端阅览
潘惠琳,蒋佳艺,吴林育,等.咽峡炎链球菌通过上调胃癌细胞PD-L1表达介导CD8⁺ T细胞功能抑制[J].陆军军医大学学报,2026,48(06):745-756.DOI:10.16016/j.2097-0927.202601002.
PAN H L,JIANG J Y,WU L Y,et al.Streptococcus anginosus mediates CD8+ T cell dysfunction via upregulating PD-L1 in gastric cancer cells[J].J Army Med Univ,2026,48(06):745-756.DOI:10.16016/j.2097-0927.202601002.
潘惠琳,蒋佳艺,吴林育,等.咽峡炎链球菌通过上调胃癌细胞PD-L1表达介导CD8⁺ T细胞功能抑制[J].陆军军医大学学报,2026,48(06):745-756.DOI:10.16016/j.2097-0927.202601002. DOI:
PAN H L,JIANG J Y,WU L Y,et al.Streptococcus anginosus mediates CD8+ T cell dysfunction via upregulating PD-L1 in gastric cancer cells[J].J Army Med Univ,2026,48(06):745-756.DOI:10.16016/j.2097-0927.202601002. DOI:
目的
2
新近研究发现,咽峡炎链球菌(
Streptococcus anginosus
,
S. a
)可促进胃癌(gastric cancer,GC)发生,但其在胃癌进展中的作用,特别是对肿瘤免疫微环境(tumor immune microenvironment,TIME)的影响机制尚未阐明。本研究拟探讨
S. a
在进展期胃癌中的作用,并验证其是否通过诱导胃癌细胞上调程序性死亡配体1(programmed death-ligand 1,PD-L1)表达,抑制CD8
+
T细胞功能的科学假说。
方法
2
基于自产的转录组测序(RNA-seq)原始数据(
n
=98),构建
S.a
相对丰度(
S. a
score)的计算流程;另一方面,利用机器学习的方法构建特征基因模型,从公共队列的基因表达矩阵中推导
S.a
的丰度水平。基于上述方法,根据丰度中位数将胃癌患者分为
S. a
高丰度组(
S.a
high
)与
S. a
低丰度组(
S.a
low
)。结合单细胞转录组测序数据(
n
=23),分析两组患者肿瘤免疫微环境中细胞构成的差异。体外验证实验使用
S.a
处理人(NUGC-3)和鼠(TKM)胃癌细胞系8 h,通过定量PCR与Western blot检测PD-L1表达变化;并通过流式细胞术检测共培养体系中CD8
+
T细胞对
S.a
预处理胃癌细胞的杀伤功能变化。体内实验采用C57BL/6小鼠原位胃癌模型,实验组通过口服灌胃给予
S.a
菌液,对照组给予无菌培养基,持续干预6周(每组
n
=6),通过活体成像、肿瘤体积及胃重比较评估肿瘤负荷。
结果
2
胃癌组织中
S.a
的丰度显著高于正常胃黏膜(
P
=0.000 850),且高丰度与预后不良有关(
HR
=1.49,95%
CI;
1.09~2.04,
P
=0.013 9)。通过单细胞转录组数据解析TIME,发现
S.a
含量不同的胃癌组织具有显著差异的TIME细胞构成,其中
S.a
丰度高的胃癌组织中CD8
+
T细胞数量显著增多(
P
<
0.000 1),但多呈耗竭状态(
P
<
0.000 1)。我们进一步发现胃癌细胞可能是影响CD8
+
T细胞功能状态的重要细胞群体,存在一群与
S.a
丰度(Spearman’s
rho
=0.288,
P
<
0.000 1)及耗竭CD8
+
T细胞(Spearman’s
rho
=0.522,
P
<
0.000 1)均显著正相关的胃癌细胞。在机制上,
S.a
处理可显著上调胃癌细胞PD-L1的表达(
P
<
0.000 1)。共培养实验证实,经
S.a
预处理的胃癌细胞能降低CD8
+
T细胞的杀伤功能(
P
=0.000 526)。体内实验结果显示,
S.a
灌胃组小鼠的肿瘤成像(
P
=0.030 6)、肿瘤体积(
P
=0.045 3)及胃重(
P
=0.030 6)显著高于对照组。
结论
2
胃癌中丰度增加的
S.a
在重塑肿瘤免疫微环境的同时,通过诱导胃癌细胞高表达PD-L1而介导CD8
+
T细胞产生耗竭表型、协助肿瘤免疫逃逸。
Objective
2
Recent evidence shows that
Streptococcus anginosus
(
S.a
) promotes the development of gastric cancer (GC). However
its role in GC progression
particularly its impact on tumor immune microenvironment (TIME)
remains unclear. This study aims to investigate the role of
S. a
in advanced GC and test the hypothesis that
S. a
upregulates PD-L1 expression in GC cells
thereby inhibiting CD8
+
T cell function.
Methods
2
Based on in-house RNA sequencing (RNA-seq) raw data (
n
=98)
a computational pipeline was established to determine the relative abundance of
S.a
(
S.a
score). In parallel
a machine learning-based signature gene model was constructed to infer
S. a
abundance from gene expression matrices of public cohorts. Using these approaches
GC patients were stratified into
S.a
-high (
S.a
high
) and
S.a
-low (
S.a
low
) groups according to the median abundance. Single-cell RNA sequencing (scRNA-seq) data (
n
=23) were integrated to analyze differences in cellular composition within the TIME between the 2 groups. For
in vitro
validation
human (NUGC-3) and murine (TKM) GC cell lines were treated with
S.a
for 8 h
followed by quantification of PD-L1 expression
via
qPCR and Western blotting. Cytotoxic function of CD8
+
T cells against
S.a
-pretreated GC cells was evaluated by flow cytometry in co-culture systems. where
S.a
-pretreated cancer cells were incubated with CD8⁺ T cells
and cytotoxicity was measured by flow cytometry. For
in vivo
validation
a C57BL/6 mouse orthotopic GC model was established; the experimental group received
S.a
bacterial suspension
via
oral gavage
while the control group received sterile culture medium
with continuous intervention for 6 weeks (
n
=6). Tumor burden was evaluated by
in vivo
imaging
tumor volume
and stomach weight.
Results
2
The abundance of
S. a
was significantly higher in GC tissues than in normal gastric mucosa (
P
=0.000 850)
and high abundance was associated with poor prognosis (
HR
=1.49
95%
CI
: 1.09 to 2.04
P
=0.013 9). Analysis of the TIME using scRNA-seq data revealed distinct cellular compositions between GC tissues with varying
S.a
levels. Notably
S.a
high
G
C tissues exhibited a significant increase in CD8
+
T cell infiltration (
P
<
0.000 1)
yet these cells predominantly displayed an exhausted phenotype (
P
<
0.000 1). Further analysis identified a subset of GC cells whose abundance is correlated positively with both
S.a
levels (Spearman’s
rho
=0.288
P
<
0.000 1) and proportion of exhausted CD8⁺ T cells (Spearman’s
rho
=0.522
P
<
0.000 1)
suggesting their potential roles in modulating CD8⁺ T cell function. Mechanistically
S.a
treatment significantly upregulated PD-L1 expression in GC cells (
P
<
0.000 1). In co-culture assays
S.a
-pretreated cancer cells impaired the cytotoxic function of CD8⁺ T cells (
P
=0.000 526).
In vivo
results demonstrated that the mice in the
S. a
gavage group exhibited significantly higher tumor bioluminescence intensity (
P
=0.030 6)
larger tumor volume (
P
=0.045 3)
and increased stomach weight (
P
=0.030 6) compared to the control group.
Conclusion
2
Enriched
S.a
abundance not only reshapes the TIME of GC
but also mediates CD8
+
T cell exhaustion and facilitates tumor immune evasion by inducing high PD-L1 expression in GC cells.
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