Our lab has previously demonstrated that
multiple sclerosis-induced spinal cord white matter damage and motor deficits are mediated by the pathological disruption of
zinc homeostasis. Abnormal vesicular
zinc release and intracellular
zinc accumulation may mediate several steps in the pathophysiological processes of
multiple sclerosis (MS), such as matrix
metallopeptidase 9 (MMP-9) activation, blood-brain barrier (BBB) disruption, and subsequent immune cell infiltration from peripheral systems.
Oral administration of a
zinc chelator decreased BBB disruption, immune cell infiltration, and spinal white matter myelin destruction. Therefore, we hypothesized that
zinc released into the extracellular space during MS progression is involved in destruction of the myelin sheath in spinal cord white mater and in generation of motor deficits. To confirm our previous study, we employed
zinc transporter 3 (ZnT3) knockout mice to test whether vesicular
zinc depletion shows protective effects on
multiple sclerosis-induced white matter damage and motor deficits. ZnT3 gene deletion profoundly reduced the daily clinical score of
experimental autoimmune encephalomyelitis (EAE) by suppression of
inflammation and
demyelination in the spinal cord. ZnT3 gene deletion also remarkably inhibited formation of
multiple sclerosis-associated aberrant synaptic
zinc patches, MMP-9 activation, and BBB disruption. These two studies strongly support our hypothesis that
zinc release from presynaptic terminals may be involved in
multiple sclerosis pathogenesis. Further studies will no doubt continue to add mechanistic detail to this process and with luck, clarify how these observations may lead to development of novel therapeutic approaches for the treatment of
multiple sclerosis.