Bacteria in the human gut can directly deliver proteins into human cells, actively shaping immune responses. Led by researchers at Helmholtz Munich, with participation from Ludwig Maximilians University (LMU), Aix Marseille University, Inserm, and international partners, the consortium has discovered this previously unknown mechanism of communication between gut bacteria and human cells. The findings reveal a new way in which the gut microbiome can influence the human body and may help explain how changes in gut bacteria contribute to inflammatory diseases such as Crohn’s disease.