Promising role of D-amino acids in irritable bowel syndrome

Figure 1 Gut microbiota could contribute to the production of D-amino acids, which might play key roles in irritable bowel syndrome via direct action on the gut and/or indirect action through the gut-brain axis with emotional stability. Fecal microbiota transplantation consists of fecal microbiota infusion from a healthy donor into a recipient subject, which has been also shown to be a promising therapy for irritable bowel syndrome. Arrowheads mean stimulation and/or augmentation whereas hammerheads represent inhibition. Note that some critical events such as reactive oxygen species production, immune activation, and/or cytokine-induction have been omitted for clarity.