Glutamine and CXC chemokines IL-8, Mig, IP-10 and I-TAC in human intestinal epithelial cells

Backgrounds & Aims: Chemokines are a family of small proteins involved in immune and inflammatory responses. Human intestinal epithelial cells act as a sentinel in the immune response and produce CXC chemokines such as IL-8, Mig, IP-10 and I-TAC. Glutamine has various effects on immuno-inflammatory response in human intestine. Methods: The present study aimed to determine the effect of glutamine on the IL-8, Mig, IP-10 and I-TAC production by ELISA and their mRNA level by RT-PCR (expressed as % gapdh) in two human intestinal epithelial cell lines Caco-2/TC7 and HCT-8 under basal conditions or during stimulation with combined cytokines. Results: Under basal conditions, studied chemokines were not influenced by glutamine. When intestinal epithelial cells were stimulated with cytokines, increasing concentrations of glutamine from 2 to 10 mM in HCT-8 cells significantly decreased I-TAC and IP-10 mRNA level (respectively 219 to 182%; P<0.01; 257 to 176%; P<0.05) and I-TAC and IP-10 production (respectively 21.2 to 13.0; P<0.05; 696 to 548 ng/prot mg; P<0.01). Glutamine also reduced IP-10 mRNA level (186 to 135%, P<0.05) in cytokines-stimulated Caco-2/TC7 cells. Conclusions: Down-regulation of CXC chemokines by glutamine could contribute to its therapeutic potential in intestinal inflammation and during critical illness.