Autoimmune myasthenia gravis: autoantibody mechanisms and new developments on immune regulation.

PURPOSE OF REVIEW: Myasthenia gravis is due to autoantibodies against components of the neuromuscular junction. Here, we analyzed the latest concepts of the physiopathological mechanisms and highlighted the recent findings about the immune-regulatory and etiological mechanisms.

RECENT FINDINGS: According to their target, autoantibodies differentially alter the neuromuscular transmission in myasthenia gravis. In myasthenia gravis patients with anti-AChR antibodies, complement plays a major role and modulation of its activity could be beneficial. In myasthenia gravis patients with anti-MuSK antibodies, not only muscle-specific kinase but also presynaptic and postsynaptic components seem to be affected. As for double-seronegative myasthenia gravis patients, their number has decreased significantly: new and already well known targets have been discovered recently. The production of these autoantibodies is the consequence of immune dysregulation. MicroRNAs appear to be new key mediators in the immunoregulatory processes. An environmental event could induce abnormal expression levels of microRNA that could lead to an excessive activation of inflammatory pathways, as observed with double-stranded RNA mimicking viral infection.

SUMMARY: A better understanding of the pathogenic effects of the distinct myasthenia gravis autoantibodies may lead to new therapeutic interventions according to the myasthenia gravis subtype. Future investigations on the immunoregulatory mechanisms will also lead to therapeutic avenues able to restore the balance of the immune system and possibly lead to long-term remissions.