Correlation Between AchRab In Thymus Extract And Non-neuronal Cholinergic System In The Thymocyte Of Myasthenia Gravis

Background and objectiveMyasthenia gravis is an acetylcholine receptor antibody (AchRab) mediated, cellular immunity dependent, complement participation at the neuromuscular junction of the autoimmune disease, and the incidence key lies in MG patients who are the existence of the abnormal immune response against AchR. Relevant data shows that approximately75%patients with MG were accompanied by thymus abnormalities, in which50%to60%were thymus hyperplasia and10%to15%were thymoma. In addition,33%to75%of thymoma patients were accompanied by MG. This experiment indicates that the pathogenesis of the MG is closely related to thymus dysfunction, but the specific mechanism is still not clear. This experiment is to explore that expression and significance of choline acetyltransferase and nicotinic acetylcholine receptor in non-neuronal cholinergic system in the thymus of myasthenia gravis, and correlation with acetylcholine receptor antibody in the thymus extract.MethodsImmunohistochemistry was used to compare the protein expression level of choline acetyltransferase (CHAT) and N-type acetylcholine receptor (nAchR) in the thymus of myasthenia gravis. The content of acetylcholine receptor antibody in the thymus extract was detected by ELISA. By Pearson correlation analyzed correlation between the content of AchRab and the expression of CHAT or nAchR.Results1. The protein expression level of choline acetyltransferase in the thymus of myasthenia gravis was lower than that of the normal group. In the thymus of myasthenia gravis, the average optical density of CHAT in the thymoma group and thymus hyperplasia group was higher than that of the thymus atrophy group. Difference of the protein expression level of CHAT between the thymoma group and the thymus hyperplasia group was no statistical significance. The protein expression level of nAchR in the thymus of myasthenia gravis was lower than that of the normal group. The protein expression level of nAchR in the thymoma group was lower than that of the thymus hyperplasia group. Difference of the protein expression level of nAchR between the thymoma group and the thymus atrophy group was no statistical significance. Difference of the protein expression level of nAchR between the hyperplasia group and the thymus atrophy group was no statistical significance.2. Compared with the normal control group, the content of AchRab in the thymoma group and the thymus hyperplasia group increased (P<0.05), but the difference in content of AchRab in the thymus atrophy group was not statistically significant (P>0.05).Compared with the thymus atrophy group, the content of AchRab in the thymoma group and thymus hyperplasia group was increased (P <0.05).The content of AchRab between the thymoma group and the thymus hyperplasia group was not significant difference (P>0.05).3. The protein expression of CHAT in the thymus hyperplasia group and the thymoma group and the content of AchRab in the thymus extract were positively correlated (P<0.05), but the protein expression of nAchR and the content of AchRab were not related (P>0.05); In the atrophy group and the normal control group, the protein expression of CHAT and nAchR and the content of AchRab in the thymus extract also was not related (P>0.05).Conclusion1. Change in protein expression level of nAchR and CHAT in thymus of MG patients may be one of the pathogenesis of MG, thus it provides a new target for therapy in the future.2. The protein expression level of CHAT in the thymus hyperplasia group and the thymoma group was positively correlated with the content of AchRab in the thymus extract, this shows that CHAT in the thymus may be involved in the production of AchRab.3. This further confirmed that the thymus is one of the sources to produce AchRab, so providing further theoretical basis for the surgical removal of the thymus for myasthenia gravis.