Gene Expression Of The Pallium In Experimental Autoimmune Myasthenia Gravis With Dysfunction Of Central Nervous System

AIM : Myasthenia gravis(MG) is a kind of autoimmune disease mainly causes muscle weakness due to dysfunction of the neuromuscular transmission. However, it was found during clinical work that part of the patients suffered from MG accompanied with dysfunction of central nervous system. It was discovered that central nervous system(CNS) involved in MG , there is secretion of the acetylcholine receptor antibody(AChRAb) in MG's cerbral spinal fluid which may bind to the neuronal-AChR of the CNS. The researchers also found that IgG derived from the patients suffered from MG may bind to the neuronal-AChR of CNS, which may cause dysfunction of the CNS in rats. An experimental autoimmune myasthenia gravis(EAMG) model with the CNS dysfunction was set up by injection of IgG purified from MG into the CNS. The following studies based on the above animal models focused on the relationship between the CNS dysfunction during the onset of MG and the variations of the molecules including IL-1, IL6, TNF-a , NO/NOS, AChE and Fas. Meanwhile, it was proved in the celllevel that the AChRAb derived from the patients suffered from MG may bind to the nerve-AChR of the CNS and lead to alteration of the cytoplasmic concentration of calcium in CNS. Whether all of the above findings are based on more deep-seated mechanisms has not been discussed. This study is to seek experimental evidence for the pathogenesis of the dysfunction of the CNS in MG by analyzing the gene expression of the pallium in EAMG models with dysfunction of the CNS in SD rats.METHODS : The immunoglobulins were purified from MG patients and those of the healthy control serum by Protein G method respectively. Then the immunoglobulins were injected into the lateral ventricles of the experimental SD rats and those of the control group respectively. Three weeks later, the total RNA from the fresh pallium of all rats were extracted and examined whether there is a degradation. The mRNA were retro-transcribed to cDNA probes by Schena method. After purification, the cDNA probes of the experimental group and those of the control group were marked with Cy5-dUTP and Cy3-dUTP respectively. The cDNA probes hybridized with the pre-hybridized cDNA microarray. The chip was scanned with GenePix 4000B scanner and the intensities of Cy5 and Cy3 were analyzed with the image proposal software GenePix Pro 3.0. The obviously variant gene expressions were analyzed in GeneBank database. RESULTS: The result of the gel electrophoresis at -20C and 70C in each group showed that there is no prominent degradation of the RNA. Among 2000 genes there were 46 differences including 17 complete gene sequences and 29 ESTs, of which 42 expressed higher and 4 lower in the experimental pallium than the controlgroup. The genes with obviously variant expression include signal transduction related genes, cell basic metabolism related genes, protein transportation related genes, cell division cycle related genes, cytoskeleton and motor protein genes, immune related genes and ion channel related genes.CONCLUSIONS: Many genes expressed differently in the cortex between the experimental group and the control group, which means these genes are involved in the onset of the CNS dysfunction in MG. It is indicated that the physiological activities of the neurons and the glia cells in the CNS are disturbed and the proliferative capacity of the glia cells and the plasticity of the neurons are decreased during the onset of MG. Some of the different gene expressions may induce abnormal reactions of the immune system to antigens expressed on the surface of normal cells, which may play a important role in the onset of MG. On the other hand, the regulation of some genes may be involved in the compensatory mechanisms that are initiated when the autoimmune reaction is too drastic to endure during the process of MG, which alleviates the pathological damage to a certain extent. The differently expressed genes with function known offer relatively clear direction for exploration of the mechanisms of dysfunction of the CNS in...