A gut feeling about murine syngeneic GVHD.

Murine syngeneic graft-versus-host disease (SGVHD) results in chronic colon and liver inflammation following syngeneic bone marrow transplantation (BMT) and treatment with the calcineurin inhibitor, cyclosporine A (CsA). SGVHD was initially thought to arise as a result of an autoreactive immune response, but more recently it has been shown that enhanced antimicrobial responses develop in SGVHD mice. Consequently, we performed studies to analyze the role of the microbiota in the development of murine SGVHD. Treatment with broad-spectrum antibiotics eliminated disease-associated inflammatory immune responses and pathology, linking the role of the microbiota and microbial-specific immunity to the development of murine SGVHD. In a broader context, these results bring into question the role that anti-microbial immune responses play in post-transplant immune pathologies that develop following allogeneic stem cell transplantation and use of calcineurin inhibitors.