Introducing Autoimmunity at the Synapse by a Novel Animal Model of Experimental Autoimmune Myasthenia Gravis

The neuromuscular junction (NMJ) is a peripheral synapse between motor neurons and skeletal muscle fibers that controls muscle contraction. The NMJ is the target of various disorders including myasthenia gravis (MG), an autoimmune disease in which auto-antibodies (auto-Abs) attack the synapse, and thus cause muscle weakness in patients. There are multiple auto-Abs in the MG patient sera, but not all the Abs are proven to be pathogenic, which increases the difficulties in clinical diagnoses and treatments. To establish the causative roles of auto-Abs in MG pathogenesis, the experimental autoimmune MG (EAMG) induced by the active immunization of auto-antigens (auto-Ags) or the passive transfer of auto-Abs is required. These models simulate many features of the human disease. To date, there are three kinds of EAMG models reported, of which AChR-EAMG and MuSK-EAMG are well characterized, while the recent LRP4-EAMG is much less studied. Here, we report a current summary of LRP4-EAMG and its pathogenic mechanisms. The features of LRP4-EAMG are more similar to those of AChR-EAMG, indicating a similar clinical treatment for LRP4- and AChR-positive MG patients, compared to MuSK-positive MG patients.