The gut is considered a key immune organ and it harbors millions of microorganisms.(bacteria) These microorganisms vary from person to person based on genetics among other factors. Alterations in the microorganisms found in the gut have been associated with gastrointestinal (GI) disease states and with other autoimmune conditions. By analyzing GI microorganisms in people diagnosed with MS and comparing it to those of healthy controls we hope to better understand the role GI microorganisms play in immune function and disease course. Previous research has shown that changes in microorganisms may lead to altered immune responses in the central nervous system (CNS). For example, an animal model of human MS suggests that altering certain bacterial populations normally present in the gut leads to the development of CNS autoimmunity ( your immune response to your own cells) . In contrast, other bacteria protect against inflammation within the brain. Altogether, these data suggest that bacteria play a far larger role than previously anticipated and that keeping an adequate balance of microbial populations in the gut may be essential to prevent autoimmunity.