Mazmanian's research investigates the symbiotic relationship between beneficial bacteria and their hosts. In seminal work, Mazmanian discovered the first microbial molecule that has direct beneficial effects on mammals. Working in
Dennis Kasper's lab, he showed in 2005 that a particular bacterial species,
Bacteroides fragilis, from the human microbiome augments
immune function and balances a dysregulated immune system. Mazmanian has described and defined a novel paradigm in science whereby the gut microbiome intricately controls the development and function of the mammalian
immune system. These discoveries include the demonstration that
B. fragilis can treat experimental
inflammatory bowel disease by inducing the activity of protective, regulatory immune cells. Further, his laboratory revealed that the gut microbiome impacts
autoimmune diseases such as experimental
multiple sclerosis. Mazmanian has also been involved in several ventures, having founded Axial Biotherapeutics and Symbiotix Biotherapies. Axial aimed to 'microbiota analysis to better understand the relationship between microbes and the central nervous system', and raised $102m with early investors including Longwood Fund.
The New York Times noted Symbiotix as 'developing a complex sugar called PSA, which is associated with Bacteroides fragilis, into treatments for intestinal disease and multiple sclerosis'. He also serves on the scientific advisory board of over a dozen companies, academic centers and not-for-profit foundations. == Personal life ==