Our fecal microbiota study as well as other studies has suggested that Bacteroidetes family members might be linked with healthy state. Therefore, we isolated a number of human upper gut commensal bacteria of the Bacteroidetes family and tested their ability to suppress disease in experimental autoimmune encephalomyelitis (EAE), an experimental model of MS. Previously we showed that PLP91-110 induced EAE in HLA-DR3DQ8 transgenic mice expressing MS susceptible HLA-class II genes. EAE was induced in HLA-DR3DQ8 transgenic mice with PLP91-110 peptide and then day 7 post-immunization, animals were treated with Prevotella histicola, Prevotella melaninogenica, Capnocytophaga sputigena or medium. Among the gut commensals tested, only P. histicola lowered disease incidence and severity compared to untreated animals or those treated with other bacteria. The brain and spinal cord had decreased inflammation and demyelination in P. histicola treated group compared to other treated or control group. Our study provides compelling evidence that administration of gut commensals may regulate a systemic immune response and have a possible role in the treatment of autoimmune diseases. We also have a patent filed on using P. histicola for treating autoimmune diseases.

The major projects includes- i) preclinical testing of human commensal in animal model for therapeutic efficacy; ii) deciphering the mechanism by which P. histicola suppress disease in animal model of MS utilizing various transgenic and knockout mice; and iii) analyzing therapeutic potential of combination therapy using P. histicola with conventional MS drugs such as Glatiramer acetate and Interferon-β.