Some Crohn’s genes make cells deaf to messages from good gut bacteria
When it works, genetic-microbe communication link helps calm inflammation

MESSAGE RECEIVED A microbe called Bacteroides fragilis (left image, boxed) sends out messages that calm the immune system, quelling inflammation in mouse intestinal cells (left, bottom half). These messages rest in pouches called outer membrane vesicles (yellow bubbles in reconstruction of microbe at right). Defective genes linked to Crohn’s disease might make it hard for people to get such messages.
Mark Ladinsky and Greg Donaldson/Caltech