Activation of the kappa-opioid receptor in Caco-2 cells decreases interleukin-8 secretion.

The immunomodulatory effects of kappa-opioid agonists at the intestinal epithelial level are not well characterized. In the present study, we determined that Caco-2 cells express the kappa-opioid receptor and its activation by trans-(+/-)-3,4-dichloro-N-methyl-N[2-(1-pyrolidinyl)cyclohexyl]benzeneacetamide methanesulfonate (U-50488) leads to decreased interleukin-8 secretion in the presence of interleukin-1beta. These effects were detected over a wide range (10 nM-50 microM) of U-50488 concentrations and were reversible using the kappa-opioid receptor antagonist nor-binaltorphimine. Our data suggest that activation of kappa-opioid receptors on Caco-2 cells decreases interleukin-8 secretion and thus may alter the chemotactic stimulus at the epithelial level.