Anorexia nervosa symptoms are induced after specific gut microbiota dysbiosis transfer in germ-free mice.

Anorexia nervosa (AN) is the most severe and life-threatening eating disorder. Its pathophysiology remains largely unknown, and no effective treatment currently exists for severe forms of the disease. Gut microbiota (GM) dysbiosis has been consistently reported in AN; however, no study has yet considered the role of the microbiota within the full spectrum of AN symptoms. To investigate the direct involvement of the microbiota in disease symptoms, we developed a murine model of fecal microbiota transplantation (FMT), using germ-free BALB/c mice colonized with fecal samples from well-characterized AN patients and healthy controls. Physiological, organ, and behavioral parameters were systematically monitored. We found that key AN-related features (including food restriction, anxiety-like behavior, physical hyperactivity, and elevated inflammatory responses) were transmitted to germ-free mice following transplantation with AN-derived microbiota. Likewise, organ-specific alterations associated with AN, such as liver dysfunction and disruption of ovarian follicles, were also reproduced. In conclusion, we demonstrate that the transfer of AN microbiota induces behavioral, physiological, and organ-level alterations reminiscent of the human disease. These findings highlight a major role of the gut microbiota in the symptomatology and progression of AN and open new therapeutic perspectives targeting this ecosystem.