NAMPT and inflammatory bowel disease: Nicotinamide phosphoribosyltransferase is significantly upregulated in IBD and has recently been identified as a marker of IBD severity in children; its inhibitor, FK866, inhibits the development of inflammation, suggesting that FK866 can inhibit M1 polarization by inhibiting NF-κB and orienting macrophage polarization toward M2 [94, 95].