Brain-gut interactions in inflammatory bowel disease

Psycho-neuro-endocrine-immune modulation through the brain-gut axis likely has a key role in the pathogenesis of inflammatory bowel disease (IBD). The brain-gut axis involves interactions among the neural components, including (1) the autonomic nervous system, (2) the central nervous system, (3) the stress system (hypothalamic-pituitary-adrenal axis), (4) the (gastrointestinal) corticotropin-releasing factor system, and (5) the intestinal response (including the intestinal barrier, the luminal microbiota, and the intestinal immune response). Animal models suggest that the cholinergic anti-inflammatory pathway through an anti-tumor necrosis factor effect of the efferent vagus nerve could be a therapeutic target in IBD through a pharmacologic, nutritional, or neurostimulation approach. In addition, the psychophysiological vulnerability of patients with IBD, secondary to the potential presence of any mood disorders, distress, increased perceived stress, or maladaptive coping strategies, underscores the psychological needs of patients with IBD. Clinicians need to address these issues with patients because there is emerging evidence that stress or other negative psychological attributes may have an effect on the disease course. Future research may include exploration of markers of brain-gut interactions, including serum/salivary cortisol (as a marker of the hypothalamic-pituitary-adrenal axis), heart rate variability (as a marker of the sympathovagal balance), or brain imaging studies. The widespread use and potential impact of complementary and alternative medicine and the positive response to placebo (in clinical trials) is further evidence that exploring other psycho-interventions may be important therapeutic adjuncts to the conventional therapeutic approach in IBD.