There is evidence that the development of certain autoimmune diseases may be associated with a bacterial or viral infection that stimulates production of antibodies and immune cells called T cells, which are targeted against bacterial proteins that closely resemble "self" proteins, leading to crossreactivity with healthy tissues. Dr. Gennaro De Libero from University Hospital in Basel, Switzerland, and colleagues identified a different mechanism where bacterial infections promote activation of T cells that recognize molecules called glycosphingolipids (GSL) that are present in bacteria and humans. The researchers show that infection with some bacteria or even just exposure to pieces of the outer wall of the bacteria results in an increase in "self" GSL synthesis by cells that promote the immune response and subsequent stimulation of autoreactive GSL-specific T cells.
"Collectively, these findings suggest that recognition of self by infection is an important mechanism leading to autoreactive T cell activation and, possibly, participates in the pathogenesis of some autoimmune diseases, such as MS and GBS, in which the anti-GSL T cell response may be important," writes Dr. De Libero. The authors suggest that although the autoreactive T cells may play a useful role in promoting the immune response to infection, in the absence of infection the GSL autoreactive T cells might seek out the abundant "self" GSLs that can be found in the nervous system, resulting in degradation of brain and nerve tissue as is seen in patients with MS and GBS.