Online

Spear, Estelle Trego

Neuroscience Graduate Program

2018

Ph. D.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that causes motor, visual, and sensory symptoms. Patients also experience constipation, which is not yet understood, but could involve dysfunction of the enteric nervous system (ENS). Autoimmune targeting of the ENS occurs in other autoimmune diseases that exhibit gastrointestinal (GI) symptoms, and similar mechanisms could lead to GI dysfunction in MS. Here, we characterize GI dysmotility in the experimental autoimmune encephalomyelitis (EAE) model of MS and test whether autoantibodies targeting the ENS are present in the serum of MS patients. Male SJL or B6 mice were induced with EAE by immunization against PLP139-151, MOG35-55, or mouse spinal cord homogenate, and monitored daily for somatic motor symptoms. EAE mice developed GI symptoms consistent with those observed in MS. In vivo motility analysis demonstrated slower whole GI transit, and decreased colonic propulsive motility. EAE mice had faster rates of gastric emptying, with no changes in small intestinal motility. Consistent with these results, ex vivo evaluation of isolated colons demonstrated that EAE mice have slower colonic migrating myoelectric complexes and slow wave contractions. Immunohistochemistry of EAE colons exhibited a significant reduction in GFAP area of ENS ganglia, with no changes in HuD, S100, or neuron numbers. To test whether antibodies in MS bind to ENS structures, we collected serum samples from MS patients with constipation and without constipation, and healthy control patients without constipation. Immunoreactivity was tested using indirect immunofluorescence by applying serum samples to guinea pig ENS tissue. MS serum exhibited significantly higher immunoreactivity against guinea pig ENS than control patients, which was particularly evident in MS patients who did not experience constipation. There was no significant difference in immunoreactivity between MS patients with and without constipation. Targets of human MS and mouse EAE serum include enteric glia and neurons. Taken together, these data validate EAE as a model for constipation in MS, and support the concept that this symptom involves changes within the neuromuscular system of the colon. EAE mice develop symptoms consistent with constipation that affects functional ENS networks and may result in structural or phenotypic changes at the cellular level. Serum immunoreactivity suggests that autoantibodies could play a role in the development of constipation in MS by targeting the ENS itself.