Résumé :
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Communication n° 569 The primary autoantigen in myasthenia gravis, the acetylcholine receptor (AChR), is clustered and anchored in the postsynaptic membrane of the NMJ by rapsyn. Previously, we found that the overexpression of rapsyn by in vivo electroporation confers resistance to experimental autoimmune myasthenia gravis (EAMG) in treated legs of susceptible rats. Therefore, we investigated the effect of rapsyn overexpression in chronic EAMG, 6 weeks after immunization with Torpedo AChR. Despite of the presence of high titers of anti-AChR antibodies and activated complement in the endplates, rapsyn overexpression resulted in an increase of AChR levels in ongoing chronic EAMG. Moreover the crosslinking of AChR by rapsyn was increased in membrane extracts of rapsyn treated muscles. The results suggest that rapsyn might be an important factor for the severity of the disease, suggesting that even a relatively small upregulation of rapsyn expression in susceptible individuals, might be therapeutically helpful.
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