Abstract:

Objective To discuss the expression levels of mitochondrial autophagy and apoptosis-related genes in peripheral blood mononuclear cells （PBMCs） in the patients with myasthenia gravis （MG），and to clarify its diagnostic value for MG. Methods The PBMCs from 50 healthy controls （control group） and 50 MG patients （MG group） were collected and extracted. Real-time fluorescence quantitative PCR （RT-qPCR） and Western blotting methods were used to detect the expression levels of mitochondrial autophagy factors phosphatase and tensin homolog （PTEN）-induced kinase 1 （PINK1）， E3 ubiquitin-protein ligase PARK2 （Parkin）， ubiquitin-binding protein p62 （p62）， microtubule-associated proteins light chain 3 type Ⅱ （LC3Ⅱ）， and apoptotic factors cytochrome C （Cyt-C）， B cell lymphoma-2 （Bcl-2）， Bcl-2-associated X protein （Bax）， cysteine-containing aspartic acid protease 3 （caspase 3）， and cysteine-containing aspartic acid protease 9 （caspase 9） mRNA and protein. Different cut-off values were set based on the mRNA detection results， and the corresponding sensitivity and specificity at each cut-off value were calculated. The receiver operating characteristic （ROC） curve was drawn. Results Compared with control group， the expression levels of autophagy factors PINK1， Parkin， and LC3Ⅱ mRNA and protein in the PBMCs in MG group were significantly decreased （P<0.01）， while the expression levels of p62 mRNA and protein were increased （P<0.05 or P<0.01）. The expression levels of apoptotic factors Cyt-C， Bax， caspase 3， and caspase 9 mRNA and protein were significantly increased （P<0.05 or P<0.01）， and while the expression levels of Cyt-C mRNA and protein were increased （P<0.05 or P<0.01）， and the expression levels of Bcl-2 mRNA and protein were significantly decreased （P<0.01）. The ROC curve analysis results showed that the area under the curve （AUC） for PINK1， Parkin， p62， and LC3Ⅱ were 0.969 6 （95%CI： 0.943 5-0.995 7）， 0.944 0 （95%CI： 0.904 7-0.983 3）， 0.855 6 （95%CI： 0.776 7-0.934 5）， and 0.908 8 （95%CI： 0.852 6-0.965 0） （P<0.01）， respectively，and the sensitivities were 92%， 92%， 78%， and 84%， and the specificities were 88%， 82%， 92%， and 82%， respectively； whereas the AUC for Cyt-C， Bax， Bcl-2， caspase 3， and caspase 9 was 1.000 （P<0.01）， and the sensitivity and specificity reached 100%. Conclusion Mitochondrial autophagy disorder and increased apoptosis are found in the PBMCs in the patients with MG， which has a higher guiding value for clinical diagnosis of MG.

Key words: Myasthenia gravis, Mitophagy, Apoptosis, Peripheral blood mononuclear cell, Diagnostic value