The Effect of Bifidobacterium infantis Treatment on Autoimmune Myocarditis
Aoife M. Murray, David Luckey, Eric V. Marietta, Chella S. David, and Veena Taneja
1Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA 2National University Ireland Galway, School of Medicine 3Department of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
Autoimmune myocarditis is an inflammatory disease of unknown etiology that can lead to dilated cardiomyopathy (DCM) resulting in death. Recent studies have shown that Bifidobacterium infantis, a major gut commensal bacterium colonizing humans, has immunosuppressive properties and may play an immunomodulatory role in extra intestinal autoimmune diseases.
Previously, we have shown that the gut may play an important role in humanized mouse model of spontaneous autoimmune myocarditis. Mice expressing HLA-DQ8/ Abo/NOD, are gluten sensitive and develop DCM. The aim of this study was to determine if treatment with Bifidobacterium infantis can suppress the autoimmune response observed before disease development.
HLA-DQ8 mice were treated with B. infantis or medium alone (control) every other day by oral gavage for 2 weeks. The effect of B. infantis treatment was studied on cellular and humoral response. Antibodies against cardiac myosin and tissue transglutaminase (tTG) were measured in sera, collected after treatment, by ELISA. Immune response to cardiac myosin was measured by in vitro T-cell proliferation and cytokine production.
No suppression of autoreactive anti-cardiac myosin or anti-tTG antibody production was observed after treatment, suggesting B-cell response in myocarditis in humanized mice is not amenable to manipulation by B. infantis treatment. However, B. infantis treatment suppressed cardiac myosin-specific T cell response and production of pro-inflammatory cytokines.
In conclusion, our study showed that B. infantis could be a potential therapeutic treatment for autoimmune myocarditis, and it would be pertinent to further explore the protective and therapeutic role of B. infantis and other commensals in extra-intestinal autoimmune diseases.