ADIPOR2 and inflammatory bowel disease: APN may interfere with cell communication, lipid, organic acid, oxygen-containing compounds, organonitrogen compounds and peptide hormone metabolism in IBD individuals through AdipoR1 or AdipoR2, but regulates neural and peripheral immune by AdipoR1 but not AdipoR2 and mediates nutritional and energy homeostasis through AdipoR2 but not AdipoR1.