LAUSR

Background: Exclusive enteral nutrition (EEN) therapy using a polymeric formula (PF) can substantially attenuate intestinal inflammation in Crohn’s disease (CD) patients. However, the mechanism(s) by which EEN suppresses inflammation are not yet fully understood. The aims were to examine cellular mechanism(s) through which EEN may suppress inflammation and investigate potential pathways to enhance anti-inflammatory properties of EEN. Methods: Glutamine, arginine, vitamin D3, and &agr; linolenic acid (ALA), present in PF, along with curcumin, were identified as immunoactive nutrient therapies. Tumor necrosis factor (TNF)–&agr;–exposed HT-29 colonic epithelial cells were used to investigate the immunosuppressive activity of the nutrients by assessing their effect on cell viability, cell activity, chemokine response (interleukin-8 [IL-8]), nuclear factor (NF)–&kgr;B, P38 mitogen-activated protein kinase, I&kgr;B kinase (I&kgr;&kgr;), and nitric oxide (NO). Results: Cellular viability and activity were maintained with all nutrient treatments. Glutamine, arginine, and vitamin D3, but not ALA, significantly attenuated IL-8 production. Glutamine and arginine led to phosphorylation blockade of the signaling components in NF-&kgr;B and P38 pathways, reduction in kinase activity, and enhancement in NO production. Combining glutamine, arginine, and curcumin at optimal concentrations completely abolished the IL-8 response. Conclusions: These data indicate that glutamine, arginine, and vitamin D3 can suppress inflammation at concentrations equivalent to those used in PF. The mechanisms of this action were mediated through influencing the NF-&kgr;B and P38 cascades. Glutamine and arginine-fortified PF with curcumin might be a promising option to enhance the effectiveness and expand the scope of EEN therapy in CD treatment.