Influence of diet on axonal damage in the EAE mouse model of multiple sclerosis

Numerous studies have shown that diet influences the development of autoimmune diseases. However, the influence of diet on axonal damage occurring in EAE (experimental autoimmune encephalomyelitis) has not been examined. In the current study we compared changes in axonal damage and myelin thickness in spinal cords of sham- and MOG (myelin oligodendrocyte glycoprotein) peptide-immunized mice kept on a standard mouse chow (Teklad 7012) versus AIN-93 M chow which was developed for improved animal health. Despite that the development of clinical signs was similar in the 2 groups, there were significant differences in axonal caliber and myelin thickness. Following induction of EAE, axonal caliber was significantly reduced in mice fed Teklad diet, but not those fed the AIN diet. Concomitantly, myelin thickness was decreased by EAE in mice fed Teklad, but not AIN diet. Analysis of g-ratios showed that the increase in g-ratio with increasing axonal size was reduced in mice fed AIN diet. These findings demonstrate that differences in axonal pathology occur in the absence of observable differences in clinical signs, and that inter-study comparisons may be confounded by differences in dietary care.