Investigating mechanisms underlying the development of paralysis symptom in a model of MS.

Multiple sclerosis (MS) is an autoimmune neurodegenerative disorder with approximately 80 % of patients suffering from pain and 50 % from paralysis. Using a rodent model for MS, experimental autoimmune encephalomyelitis (EAE), researchers have predominately investigated paralysis/motor disease as the clinical symptom of EAE with fewer studying MS/EAE pain. However, in EAE, all mice exhibit a pain like phenotype and only a subset progresses to paralysis. Despite extensive research characterizing the disease pathology, the etiology that contributes to the range of pain and motor symptom occurrence in MS remains understudied. This is the first study to dissect MS symptom pathophysiology, using the non-PTX EAE model, in mice that experience mechanical hypersensitivity (pain-like phenotype) with and without paralysis. We found that mechanical hypersensitivity experienced by mice with or without paralysis is comparable between the two groups, irrespective of sex. In addition, there is a significant increase in the activation and infiltration of immune cells, demyelination, and heightened protein expression of B cell chemoattractant CXCL13 within the spinal cord of mice exhibiting mechanical hypersensitivity and paralysis, compared to mice only experiencing mechanical hypersensitivity.