发酵支原体和梨支原体感染致死小鼠胸腺细胞的损伤及其Bax/Bcl-2表达

Experimental study on the lesion of mice thymus cells and the expression of Bax/Bcl-2 induced lethally by Mycoplasma fermentansand Mycoplasma pirum

目的探讨发酵支原体(Mf)和梨支原体(Mpi)感染致死小鼠胸腺细胞的损伤及其Bax/Bcl-2的表达。方法清洁级ICR小鼠47只,随机分为免疫抑制组(n=35)和非免疫抑制组(n=12),隔日腹腔注射环磷酰胺(50mg/kg.d)5次制成免疫抑制模型。免疫抑制组分为Mf感染组、Mpi感染组和生理盐水(NS)对照组,分别腹腔注射0.3mL Mf和Mpi标准菌株(6×108-9/mL)及NS;非免疫抑制组取正常小鼠腹腔注射同等剂量的Mf。计算各组小鼠死亡率,取其血清进行支原体分离培养,电镜观察小鼠胸腺细胞超微结构,免疫组织化学法分析小鼠胸腺Bax/Bcl-2的表达。结果 Mf和Mpi感染免疫抑制组死亡率与NS组及非免疫抑制Mf组比较,差异均有统计学意义(P<0.05);感染组相应支原体培养阳性;超微结构观察表明,Mf和Mpi感染组胸腺细胞凋亡显著;同时免疫组化结果分析显示Mf和Mpi感染组胸腺Bax/Bcl-2的表达较对照组有显著提高,差异有统计学意义(P<0.05)。结论发酵支原体和梨支原体感染可诱导小鼠胸腺细胞的凋亡,并促进小鼠胸腺组织中Bax的表达。

The purpose is to study the lesion of mice thymus cells and the expression of Bax/Bcl-2 induced by Mycoplas- ma fermentans （Mr） and Mycoplasma pirum （Mpi）. Forty-seven ICR mice （clean class） were randomly divided into immuno suppressive group （n= 35） and non-immunosuppressive group （n= 12）. The immunosuppressive model was made by intraper- itoneal injection with cyclophosphamide （50 mg/kg . d） every other day. The immunosuppressive groups of mice were divided into Mf infected group, Mpi infected group and the normal saline （NS） control group. They were respectively received 0.3 mL （6×10^8-9/mL） Mr, Mpi and the sterile normal saline by intraperitoneal injection. The non-immunosuppressive group of normal mice was received equal amount of Mf by intraperitoneal injection. The mortality rate of each group was evaluated. The serum samples from each group of mice were taken for re-cultivation of the Mycoplasma and the thymus tissue of the dead mice were subjected to ultrastructural observation by electron microscope. And the expression of Bax/Bcl-2 of mice thymus were analysed with immunohistochemistry. It was found that the mortality rates of immunosuppressive groups infected with Mf and Mpi were statistical differences （P〈0.05） in comparison with the normal saline control group and Mf infected non- immunosuppressive group. The Mycoplasma was positive in infected experimental group. Ultrastructural observation showed that the apoptosis of thymus cell in Mf and Mpi infected group were increased dramatically. It was also found that significant enhance existed in the expression of Bax/Bcl-2 of mice thymus between the infected group and the control group by immunohis tochemistry （P〈0. 05）. It is apparent that Mf and Mpi infections may induce the apoptosis of mice thymus cell, and promote the expression of Bax in the mice thymus.