Multiple Sclerosis as a Syndrome-Implications for Future Management

Metformin treatment reduces inflammation, dysmyelination and disease severity in a mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammation, death or damage of oligodendrocytes, and axonal degeneration. Current MS treatments are non-curative, associated with undesired side-effects, and expensive, highlighting the need for expanded therapeutic options for patients. There is great interest in developing interventions using drugs or therapeutics to reduce symptom onset and protect pre-existing myelin. Metformin is a well-tolerated drug used to treat Type 2 diabetes that has pleiotropic effects in the central nervous system (CNS), including reducing inflammation, enhancing oligodendrogenesis, increasing the survival/proliferation of neural stem cells (NSCs), and increasing myelination. Here, we investigated whether metformin administration could improve functional outcomes, modulate oligodendrocyte precursor cells (OPCs), and reduce inflammation in a well-established mouse model of MS- experimental autoimmune encephalomyelitis (EAE). Male and female mice received metformin treatment at the time of EAE induction ("acute") or upon presentation of disease symptoms ("delayed"). We found that acute metformin treatment improved functional outcomes, concomitant with reduced microglia numbers and decreased dysmyelination. Conversely, delayed metformin treatment did not improve functional outcomes. Our findings reveal that metformin administration can improve EAE outcomes when administered before symptom onset in both sexes.

Cerebellar pathology in multiple sclerosis and experimental autoimmune encephalomyelitis: current status and future directions

Recent decades have witnessed significant progress in understanding mechanisms driving neurodegeneration and disease progression in multiple sclerosis (MS), but with a focus on the cerebrum. In contrast, there have been limited studies of cerebellar disease, despite the common occurrence of cerebellar symptoms in this disorder. These rare studies, however, highlight the early cerebellar involvement in disease development and an association between the early occurrence of cerebellar lesions and risk of worse prognosis. In parallel developments, it has become evident that far from being a region specialized in movement control, the cerebellum plays a crucial role in cognitive function, via circuitry connecting the cerebellum to association areas of the cerebrum. This complexity, coupled with challenges in imaging of the cerebellum have been major obstacles in the appreciation of the spatio-temporal evolution of cerebellar damage in MS and correlation with disability and progression. MS studies based on animal models have relied on an induced neuroinflammatory disease known as experimental autoimmune encephalomyelitis (EAE), in rodents and non-human primates (NHP). EAE has played a critical role in elucidating mechanisms underpinning tissue damage and been validated for the generation of proof-of-concept for cerebellar pathological processes relevant to MS. Additionally, rodent and NHP studies have formed the cornerstone of current knowledge of functional anatomy and cognitive processes. Here, we propose that improved insight into consequences of cerebellar damage in MS at the functional, cellular and molecular levels would be gained by more extensive characterization of EAE cerebellar pathology combined with the power of experimental paradigms in the field of cognition. Such combinatorial approaches would lead to improved potential for the development of MS sensitive markers and evaluation of candidate therapeutics.

Neuregulin therapy for multiple sclerosis: an each-way bet?

This scientific commentary refers to ‘Neuregulin-1 beta 1 is implicated in pathogenesis of multiple sclerosis’, by Kataria et al. (doi:10.1093/brain/awaa385).