Select Amino Acids Induced Expression of Human Beta‐Defensin in Caco‐2 cells

Host defense peptides (HDPs) are important components of the innate immune system and contribute to protection of the intestinal epithelium. Human beta defensin 2 (HBD2) is a HDP expressed by the epithelial cells of skin, gastrointestinal tract and the respiratory tract and plays an important role in protecting these tissues. The objective of this study was to investigate the role of specific amino acids in inducing human defensin‐2 in Caco‐2 cells. Previous studies showed individual amino acids such as isoleucine, glutamine, or arginine inducing HDP in epithelial cells. There appears to be a gap in information on which extent a combination of different amino acids influence the expression of beta defensins. Here we look at the role of isoleucine, arginine and glutamine (all L‐forms, individually or in combination) in inducing the expression of HBD2 in Caco‐2 cells. Cell lines were grown and exposed to different concentrations of amino acids. The effect of time and concentration of the different amino acids (alone or combined) on the expression of HBD2 was determined. HBD2 expression was evaluated using RT‐PCR with specific forward and reverse primers for HBD2. Results from our preliminary studies show that HBD2 expression by Caco‐2 cells is enhanced by a combination of at least two amino acids at a μmol concentration. Amino acids as immunomodulators have promising clinical implications in gastrointestinal disorders. (Kansas State University, NHHNSROAES)