Neurobehavioral burden of multiple sclerosis with nanotheranostics

Microglial Neuroinflammation-Independent Reversal of Demyelination of Corpus Callosum by Arsenic in a Cuprizone-Induced Demyelinating Mouse Model

Demyelination is the loss of myelin in CNS, resulting in damaged myelin sheath. Oxidative stress and neuroinflammation play a key role in inducing demyelinating diseases like MS; hence, controlling oxidative stress and neuroinflammation is important. Cuprizone (CPZ), a copper chelator, generates oxidative stress and neuroinflammation, thereby inducing demyelination. Therefore, the CPZ-induced demyelinating mouse model (CPZ model) is widely used in research. The present study was intended to unravel a mechanism of inhibition of demyelination by arsenic in a CPZ model, which is otherwise known for its toxicity. We investigated an alternative mechanism of inhibition of demyelination by arsenic through the reversal of SOD1 activity employing in silico analysis, analytical chemistry techniques, and in vitro and in vivo experiments. In vivo experiments showed protection of body weight, survivability, and myelination of the corpus callosum in CPZ and arsenic-co-exposed animals, where neuroinflammation was apparently not involved. In vitro experiments revealed that arsenic-mediated reversal of impaired SOD1 activity leads to reduced cellular ROS levels and better viability of primary oligodendrocytes. Reversal of SOD1 activity was also observed in the corpus callosum tissue isolated from experimental animals. In silico and analytical chemistry studies revealed that similar to copper, arsenic can potentially bind to CPZ and thereby make the copper freely available for SOD1 activity. Suitable neurobehavior tests further validated the protective effect of arsenic. Taken together, the present study revealed that arsenic protects oligodendrocytes and demyelination of corpus callosum by reversing CPZ-induced impaired SOD1 activity.

Amelioration of Experimental Autoimmune Encephalomyelitis in Mice by Interferon-Beta Gene Therapy, Using a Long-Term Expression Plasmid Vector

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. Repeated injections of the interferon-β (IFN-β) protein are required for relapse prevention therapy in patients with MS. IFN-β gene transfer can be an alternative treatment that continuously supplies IFN-β protein to the patient without requiring repeated injections. In a previous study, we constructed a novel long-term IFN-β-expressing plasmid vector (pMx-IFN-β). In the present study, we examined whether gene transfer of pMx-IFN-β could be effective for the treatment of MS in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. Seven days after injection of the EAE-inducing peptide, the EAE mice received hydrodynamic injections pMx-IFN-β. The severity of EAE symptoms in the pMx-IFN-β-treated mice was significantly lower for 1 month than that observed in the untreated mice. An evaluation of blood-brain barrier (BBB) function, using Evans Blue, showed that injection of pMx-IFN-β suppressed the BBB disruptions normally observed in EAE mice, while BBB disruptions remained evident in the untreated EAE mice. Histological analysis showed fewer invasive inflammatory cells in the spinal cords of the pMx-IFN-β-treated mice than in the spinal cords of the other mice. Serum interferon gamma protein (IFN-γ) concentrations in the pMx-IFN-β-treated mice were significantly lower than that in the untreated mice, indicating that IFN-β gene transfer suppressed the production of IFN-γ from pathogenic T cells. These results indicate that IFN-β transgene expression by single administration of the pMx-IFN-β can be an effective long-term treatment for MS.