ABSTRACT
Although the importance of nitric oxide (NO) on the immune system is well known, its mechanisms remain poorly described due to the involvement of different proteins and pathways and many interactions among these. NO is a free radical produced by the enzyme nitric oxide synthase (NOS) from the amino acid l-arginine. Increased reactive oxygen species (ROS) concentrations reduce the amount of bioactive NO by chemical inactivation to form toxic peroxynitrite. NO is produced as part of the inflammatory response, and so elevated NO metabolites are seen in inflammatory conditions such as in the inflammatory bowel diseases (IBDs) in which inducible NOS (iNOS) activity is related to disease activity. Because NO is synthesized from the amino acid l-arginine, dietary recommendations for boosting NO might include protein-rich meat and poultry. However, much dietary arginine is metabolized in the enterocytes limiting its availability as a NOS.
