虫草多糖调节小鼠T淋巴细胞及其亚群数量的机制研究

Mechanism in the Regulation of the Number of T Lymphocytes and Its Subsets of Normal Mice by Polysaccharides of Cordyceps Sinensis Mycelium

关键词:  冬虫夏草菌丝体  虫草多糖  T淋巴细胞亚群  凋亡  Bcl-2  Bax

Key words:  Cordyceps sinensis mycelium  cordyceps polysaccharide  T lymphocyte subgroup  apoptosis  Bcl-2  Bax

摘要:

目的 研究冬虫夏草菌丝体多糖（虫草多糖）对正常小鼠T淋巴细胞及其亚群数量的影响及可能的机制。方法 ICR小鼠，随机分成空白对照组、阳性组（香菇多糖1 mg·kg^-1）和虫草多糖高、中、低剂量（200，100，50 mg·kg^-1）组，连续腹腔注射10 d后，流式细胞仪检测外周血T淋巴细胞（CD³⁺细胞）及其亚群细胞CD4⁺CD8^-和CD4-CD8+数量、CD³⁺细胞凋亡率；MTT法测定小鼠脾淋巴细胞转化功能；实时荧光定量PCR检测脾脏组织Bcl-2 mRNA、Bax mRNA的转录水平，并测定胸腺和脾脏指数。结果 与空白对照组比较，虫草多糖能提高小鼠脾脏质量、促进未经ConA诱导的脾淋巴细胞增殖转化能力，并呈现剂量依赖性；虫草多糖高剂量组能明显增加外周血CD³⁺细胞和CD4⁺CD8^-细胞亚群的数量，降低CD4^-CD8⁺细胞亚群数量，显著提高CD4⁺CD8^-/CD4-CD8⁺的比值；高剂量虫草多糖能明显降低小鼠外周血CD³⁺细胞凋亡率，显著升高脾组织Bcl-2 mRNA转录水平和Bcl-2/Bax比值，而对Bax mRNA转录水平没有明显影响。结论 虫草多糖可刺激小鼠主要免疫器官（胸腺和脾脏）增生，提高T淋巴细胞及CD4^-CD8⁺亚群的数量，其作用机制可能与上调抑制凋亡基因Bcl-2 mRNA的转录，提高Bcl-2/Bax比值，从而抑制淋巴细胞凋亡有关。

Abstract:

OBJECTIVE To study the effect of polysaccharides of Cordyceps sinensis mycelium (cordyceps polysaccharide) on the number of T lymphocytes and its subsets of normal mice and the possible mechanism.METHODS The ICR mice were randomly divided into the blank control group, positive group (lentinan 1 mg·kg^-1), cordyceps polysaccharide groups in high, medium and low dose (200, 100, 50 mg·kg^-1). After continuous celiac injection for 10 d, the number of T lymphocytes (CD³⁺ cells) and their subgroups (CD4⁺CD8^- and CD4^-CD8⁺ cells), the apoptosis rate of CD³⁺ cells in peripheral blood were detected by flow cytometry; the transformation rates of spleen lymphocyte and the expression levels of apoptosis-related genes Bcl-2 and Bax mRNA in spleen tissue were detected by real-time PCR, and the thymus index and the spleen index were measured.RESULTS Compared with the blank control group, cordyceps polysaccharide groups significantly increased spleen weight and the transformation of spleen lymphocytes in a dose-dependent manner. High dose of cordyceps polysaccharide group could obviously increase the number of CD³⁺cells and CD4⁺CD8^- cell subsets, reduce the number of CD4-CD8+ cell subsets, and significantly increase the ratio of CD4⁺CD8^-/CD4^-CD8⁺ in peripheral blood. High dose of Cordyceps polysaccharide group significantly reduced apoptosis rate of CD³⁺ cells in peripheral blood, and the transcription levels of apoptosis-related genes Bcl-2 in spleen tissue, while no significant change in the transcription level of Bax, and the Bcl-2/Bax ratio was significantly increased accordingly.CONCLUSION Cordyceps polysaccharide stimulates proliferation of mice main immune organs (spleen and thymus) and increases the number of T lymphocytes and CD4⁺CD8^- subgroup of mice. The protective mechanism suggests that cordyceps polysaccharide upregulates the transcription levels of inhibitory apoptosis gene Bcl-2 and the ratio of Bcl-2/Bax, and then inhibits the apoptosis rate of lymphocytes.