CLDN5 and neuromyelitis optica: The decrease in expression of Claudin-5 in IBMs when exposed to NMO-IgG in the absence of any previous contact with breaching substances (i.e, such as pertussis toxin used in animal models of cerebral autoimmune disease), suggests that NMO-IgG directly contribute to the structural destabilization of the BBB from the brain compartment.