Effect of polymorphisms of Crohn disease related NOD2 gene and human beta-defensin 2 on expression of human beta-defeusin 2

Abstract

Objective To explore the effects of polymorphisms of Crohn＇s disease related NOD2 gene and human beta-defensin 2 （hBD-2） on transcription of hBD-2 gene and its mechanism. Methods I-IEK293T cells were transfected with hBD-2 gene and NOD2 eukaryotic expression plasmid, and were then stimulated with LPS, TNF-α or BAY 11-7082 （ antagonist of NF-κB） , respectively. Transcriptional activity of hBD-2 was detected afterwards. Results LPS could suppress transcription of hBD-2 （ P = 0. 020） , which was increased by TNF-α in a dose-dependent manner （P = 0. 004）. In the presence of LPS, there was significant difference in transcriptional activity of hBD-2 between wild-NOD2 transfected group and mutated NOD2 （P268S） transfected group （P = 0. 008 ）, but there was no significant difference between wild hBD-2 transfected group and mutated hBD-2 transfected group （ P =0. 053 ）. With the stimulation of TNF-α （5 ng/ml）, there was a significant difference between mutated hBD-2 transfected group and wild hBD-2 transfected group （ P = 0. 006 ）, but no significant difference between wild-NOD2 transfected and mutated NOD2 transfected group was defected （P =0. 064 ）. Pretreatment with BAY 11-7082 before TNF-α （5 ng/ml） significantly inhibited the transcriptional activity of hBD-2 （ P 〈 0.001 ）. Conclusion The polymorphism of NOD2 affects the innate expression of hBD-2, the polymorphism of site in hBD-2 promoter （-233） may lead to significant decline of the inducible expression of hBD-2, and NF-K B might be a key pathway that NOD2 protein mediates the expression of defensin. Key words: Human beta-defensin-2 ; CARD15/NOD2 ; Crohn disease ; Gene polymorphism ; Immunity, Natural