与霍乱毒素B亚单位结合的重组人AChR片断经鼻腔治疗实验性自身免疫性重症肌无力

Treatment of experimental autoimmune myasthenia gravis by nasal tolerance with a recombinant fragment of acetylcholine receptor conjugated to cholera toxin B subunit

目的探讨与霍乱毒素B亚单位结合的重组人AChRα亚单位片断(CTB-Hα1-205)治疗实验性自身免疫性重症肌无力(EAMG)的有效性和基本作用机制。方法将用AChR诱导的Lewis EAMG鼠随机分为3组:CTB-Hα1-205治疗组、Hα1-205组和CTB-HGG对照组,在诱导EAMG后第14天分别按上述3组从鼻腔滴入CTB-Hα1-205、Hα1-205和CTB-HGG。对各组进行临床分数评估、测定鼠血清中抗AChR特异抗体和淋巴细胞增殖反应。结果CTB-Hα1-205组和Hα1-205组平均临床分数均较对照组有明显减少,差异有统计学意义(均为P<0.01),同时CTB-Hα1-205组较Hα1-205组也有明显减少(P<0.05);与对照组比较,CTB-Hα1-205组和Ha1-205组血清中鼠抗AChR特异抗体IgG、IgG2a、IgG2b和IgG2c的产生均明显被抑制(P<0.01),CTB-Hα1-205治疗组的IgG、IgG2b和IgG2c较Hα1-205组低,且差异有统计学意义(P<0.05);另一方面,CTB-Hα1-205组和Hα1-205组的IgG1较对照组却有明显升高(P<0.05),同时,CTB-Hα1-205组和Hα1-205组对AChR特异性抗原的淋巴细胞增殖反应也被明显抑制(P<0.05)。结论CTB-Hα1-205比Hα1-205能更加有效治疗EAMG,其作用机制是抑制了自身抗体的产生、IgG亚型的转换和特异的淋巴细胞增殖反应。

Objective To assess the treatment effects of nasal tolerance with a recombinant fragment of acetylcholine receptor conjuga- ted to cholera toxin B subunit （CTB-Hαl-205） on experimental autoimmune myasthenia gravis （EAMG） in Lewis rats and study its underlying immunological mechanisms of action. Methods After 14 days of immunization with AChR and Freud＇s complete adjuvant, CTB-Hα1-205 （ 1 μg） , Hal-205 （400 μg） or CTB-HGG （400 μg, control group） were given nasally for 12 consecutive days and the clinical scores were evaluated for 8 weeks after immunization in EAMG rats. The levels of IgG and IgG isotype of anti-AChR in serum were determined by ELISA. Proliferative responses of lymphocytes to Torpedo AChR or concanavalin A were tested. Results As compared with the control group, the mean clinic score of the CTB-Ha1-205 and Hα1-205 group were reduced （ P 〈 0.01 ）. The CTB- Hα1-205 group showed lower mean clinic scores than the Hα1-205 group （P 〈 0.05）. The levels of IgG, IgG2a, IgG2b and IgG2c in the CTB-Hα1-205 and the Hα1-205 groups were lower than in the control group （ P 〈 0.01 and P 〈 0.05, respectively）. The levels of IgG, IgG2b and IgG2c in the CTB-Hal-205 group were lower than in the Hα1-205 group （P 〈0.05）. Whereas the levels of IgG1 in the CTB-Hα1-205 and the Hα1-205 groups were higher than in the control group （P 〈 0.05）. Proliferative responses were suppressed in response to antigen-specific stimulation in rats receiving CTB-Hα1-205 and Hα1-205 （ P 〈 0.01 ）. Conclusions Both CTB-Hal- 205 and Hα1-205 are effective to treatments EAMG in primed animals, possibly through decreasing the levels of anti-AChR total IgG,switching IgG isotype profile in serum and suppressing antigen-specific T cell proliferation. CTB-Hα1-205 appears to be more effective to EAMG.