interaction of cpg-oligodeoxynucleotides with toll like receptor 9 induces apoptosis and modulates metaloproteinase-2 activity in human intestinal epithelium

recent reports have indicated different effects of immunostimulatory sequences containing cpg-oligodeoxynucleotides (odn) on various immune cells. however, the exact role of cpg-odn in the human gut is unclear. in the present study, we assessed potential effects of cpg-odn on non lymphoid cell (intestinal epithelial cell line ht-29) on a dose-response and time-course basis. intestinal epithelial cell line ht-29 was treated with cpg-odn (cpg 2006) and lipopolysaccharide (lps) at 5, 10, 25, 50 μg/ ml and 1, 5, 10 μg/ ml concentrations, respectively. following treatments, dose- response and time-course cytotoxicity using a colorimetric method, metaloproteinase-2 (mmp-2) activity (using gelatin zymography) and apoptosis (using annexin-v flowcytometry method) assays were performed. chloroquine treatment was also used for its inhibitory effect on endosomal acidification process to verify specific cpg-odn and toll like receptor 9 (tlr9) interactions. cytotoxicity analysis of cpg-odn showed that cpg-odn increased significantly the proliferation of cpg-odn treated cells, as compared to untreated cells, at concentrations of 10-25 μg/ml (p collectively, our data indicated that intestinal epithelial cell line ht-29 is highly responsive to cpg effect in vitro and exhibits modified activities. the direct cpg-odn and tlr-9 interactions in ht-29 cells could provide new approaches in malignant tumor therapeutic strategies.