Exploring the gut-brain connectionDr. Baranzini took part in a 2019 University of Toronto study published in Cell that provided more insight into the connections between gut bacteria and MS. In mice who developed a disease similar to MS, he said, “a cell population that is responsible for producing IgA in the gut enters the circulation and goes into the brain. This was completely unexpected. The hypothesis is that these cells enter the brain in order to help with the inflammatory process.”
For the new study, Dr. Baranzini and colleagues sought to determine if IgA-producing cells play a similar role in humans with MS. They measured taxa-specific IgA coating in fecal specimens from patients with MS – 25 in remission and 11 in relapse. The patients hadn’t received treatment for MS or had not received it for at least 6 months. Researchers also examined specimens from 31 healthy controls.
“The proportion of differential IgA-bound operational taxonomic units was significantly higher in patients with MS, compared with controls,” the resarchers reported.
An analysis of cerebrospinal fluid (CSF) in a similar population found elevated levels of IgA levels during relapsed MS. “Further,” the authors wrote, “we found CSF IgA levels to be significantly higher in active MS in comparison with neurodegenerative and healthy controls, which was also the case in active neurosarcoidosis, another autoimmune neuroinflammatory disease, compared with the respective inactive disease state and controls.”
The researchers add that “these findings suggest that IgA-producing B cells either traffic to the CNS or preferentially augment local IgA production during active neuroinflammation.”
Top image credit: Govind Bhagavatheeshwaran, Daniel Reich, National Institute of Neurological Disorders and Stroke, National Institutes of Health
Image credit: Govind Bhagavatheeshwaran, Daniel Reich, National Institute of Neurological Disorders and Stroke, National Institutes of Health