Anti‐inflammatory effects of glutamine on <scp>LPS</scp>‐stimulated human dental pulp cells correlate with activation of <scp>MKP</scp>‐1 and attenuation of the <scp>MAPK</scp> and NF‐κB pathways

Abstract

Abstract Aim To evaluate the anti‐inflammatory effects of glutamine and the underlying signal pathway mechanisms in lipopolysaccharide ( LPS )‐stimulated human dental pulp cells ( HDPC s). Methods Human dental pulp cells were exposed to 10 μg mL −1 LPS and various concentrations of glutamine for 24 h. The production of PGE 2 and nitric oxide was determined by enzyme‐linked immunosorbent assay ( ELISA ) and Griess reagent kit, respectively. Cytokines were examined by ELISA , reverse transcriptase‐polymerase chain reaction ( RT‐PCR ) and real‐time PCR . i NOS and COX protein expression as well as signal pathways were accessed by W estern blot. The data were analysed by anova with B onferroni's test (α = 0.05). Results Glutamine reduced LPS ‐induced iNOS and COX ‐2 protein expression as well as production of NO and PGE 2 in a dose‐dependent fashion. Additionally, glutamine suppressed the production and m RNA expression of inflammatory cytokines including interleukin‐1β ( IL ‐1β), TNF ‐α, and IL ‐8. Furthermore, glutamine attenuated phosphorylation of extracellular signal‐regulated kinase ( ERK ), p38, c‐Jun N ‐terminal kinase ( JNK ) and IκB‐α, and nuclear translocation of NF ‐ kB p65, but enhanced mitogen‐activated protein kinase phosphatase‐1 ( MKP ‐1) expression in LPS ‐treated HDPC s. Conclusion Glutamine exerted an anti‐inflammatory effect via activation of MKP ‐1 and inhibition of the NF ‐ kB and MAPK pathways in LPS ‐treated HDPC s.