Treg depletion with a low-dose metronomic temozolomide regimen in a rat glioma model
Treg depletion with a low-dose metronomic temozolomide regimen in a rat glioma model
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DOI：
10.1007/s00262-009-0671-1
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发表时间：
2009-10-01
影响因子：
5.8
通讯作者：
Carpentier, Antoine F.
中科院分区：
文献类型：
--
作者：
Banissi, Claire;Ghiringhelli, Francois;Carpentier, Antoine F.
CD 4 + CD 25+调节性T细胞（Treg）占CD 4+人T细胞的约2-3%，是维持免疫耐受的主要贡献者。癌症患者，包括胶质母细胞瘤患者，具有增加数量的循环和肿瘤浸润性Treg，其对肿瘤特异性T细胞发挥功能性抑制。替莫唑胺（TMZ）是胶质母细胞瘤（GBM）最有效的化疗药物之一。淋巴细胞减少症是TMZ治疗的常见副作用，但这种化疗对Treg隔室的影响程度尚不清楚。因此，我们研究了不同TMZ方案对胶质瘤TMZ耐药大鼠模型中Treg细胞群的影响。费希尔大鼠。肿瘤植入后12天，TMZ口服给药，时间表设计为模拟目前在人体中使用的TMZ方案：30 mg/kg/天，持续5天，或10 mg/kg/天，持续21天。此外，还评价了两种低剂量TMZ（2和0.5 mg/kg/天，持续21天）的节律方案。使用CD 3、CD 4、CD 25和Foxp 3 mAb通过流式细胞术分析脾细胞和肿瘤浸润淋巴细胞。通过Mann-Whitney U检验、Student t检验或ANOVA检验确定统计学显著性。（0.5和2 mg/kg，持续21天）诱导Treg/CD 4+比值显著降低（13 +/-A2; p < 0.01，14 +/-A3; p < 0.05，对照组分别为19 +/-A5）。高剂量TMZ（10 mg/kg/d，共21 d或30 mg/kg，共5 d）对Treg/CD 4+细胞比例无明显影响。在肿瘤内，用0.5mg/kg TMZ方案治疗在2至3周治疗后诱导Treg/CD 4+百分比的轻微且几乎显著的降低（24 +/-Δ 9对35 +/-Δ 11; p = 0.06）。通过体外功能测试评估，低剂量节拍TMZ方案诱导的Treg耗竭伴随剩余Treg细胞的抑制功能降低。与未治疗的动物相比，用0.5 mg/kg节拍TMZ治疗减少了肿瘤进展，但效果未达到统计学显著性，表明单独的Treg耗竭不足以显著影响我们的完全建立的肿瘤模型中的肿瘤生长。低剂量节拍TMZ方案，但不是标准TMZ方案，减少了循环Treg的数量。这些结果可以在GBM的免疫方法的临床应用。
CD4+CD25+ regulatory T cells (Treg), which constitute about 2-3% of CD4+ human T cells, are the main contributors to the maintenance of immune tolerance. Cancer patients, including glioblastoma patients, bear increased number of circulating and tumor infiltrating Treg that exert functional inhibition on tumor-specific T cells. Temozolomide (TMZ) is one of the most effective chemotherapeutic agents in glioblastoma (GBM). Lymphopenia is a common side effect of TMZ treatment, but to what extent the Treg compartment is affected by this chemotherapy has been poorly investigated. We therefore studied the impact of various TMZ regimens on Treg cell population in a TMZ-resistant rat model of glioma.RG2 glioma cells were implanted s.c. in Fischer rats. Twelve days after tumor implantation, TMZ was administered orally with schedules designed to mimic the TMZ regimens currently used in humans: 30 mg/kg per day for 5 days, or 10 mg/kg per day for 21 days. In addition, two metronomic regimens with low-dose TMZ (2 and 0.5 mg/kg per day for 21 days) were evaluated. Splenocytes and tumor infiltrating lymphocytes were analysed by flow cytometry using CD3, CD4, CD25, and Foxp3 mAbs. Statistical significance was determined by the Mann-Whitney U test, the Student's t test or the ANOVA test.In the spleen of tumor-bearing animals, low-dose TMZ metronomic regimens (0.5 and 2 mg/kg for 21 days) induced a significant decrease of Treg/CD4+ ratios (13 +/- A 2; p < 0.01, 14 +/- A 3; p < 0.05, respectively, vs. 19 +/- A 5 for controls). On the contrary, high-dose TMZ regimen (10 mg/kg per day for 21 days or 30 mg/kg for 5 days) did not significantly modify the percentage of Treg/CD4+. Within tumors, treatment with the 0.5 mg/kg TMZ regimen induced a slight and nearly significant decrease in the percentage of Treg/CD4+ after a 2 to 3-week treatment (24 +/- A 9 vs. 35 +/- A 11; p = 0.06). Treg depletion induced by the low-dose metronomic TMZ regimen was accompanied by a decreased suppressive function of the remaining Treg cells as assessed by an in vitro functional test. Treatment with 0.5 mg/kg metronomic TMZ reduced tumor progression when compared to untreated animals but the effect did not reach statistical significance, indicating that Treg depletion alone is not sufficient to significantly impact tumor growth in our model of fully established tumor.A low-dose metronomic TMZ regimen, but not a standard TMZ regimen, reduced the number of circulating Tregs. These results can have clinical applications for immunotherapeutic approaches in GBM.