Mechanism of Helicobacter pylori metabolites antagonizing host innate immunity
Objective:To investigate potential mechanism of Helicobacter pylori metabolites antagonizing host innate immunity.Methods:RNA sequencing and pathway enrichment analysis were used to analyze only LPS-stimulated gastric mucosal cells GES-1,GES-1 cells co-treated with LPS and Helicobacter pylori culture supernatant,and untreated GES-1 cells.The culture supernatant of He-licobacter pylori was filtered by a 3KD ultrafiltration tube,and the filtered filtrate(metabolite part)and the retained solution(protein part)were treated with LPS-stimulated GES-1 cells to detect activity of NF-κB pathway,phosphorylation level of NF-κB,secretion levels of NF-κB pathway effectors TNF-α,IL-6 and IL-8.Identification of key metabolites by untargeted metabolic mass spectrometry.Results:Compared with GES-1 cells stimulated only by LPS,after co-treated with LPS and Helicobacter pylori culture supernatant,expression levels of various genes were regulated and tended to the level of GES-1 in untreated gastric mucosal cells,mainly in the NF-κB pathway.After co-treatment with LPS and culture supernatant of Helicobacter pylori,activity of NF-κB pathway was inhibited(P<0.05).Helicobacter pylori metabolites could inhibit the activity of NF-κB pathway,inhibit phosphorylation of NF-κB,and inhibit the secretion of NF-κB pathway effectors TNF-α,IL-6 and IL-8(P<0.05).1,5 and 25 µmol/L of Helicobacter pylori metabolite 2-D-Glu-copyranose(2DG)treatment inhibited activity of NF-κB pathway and phosphorylation of NF-κB in GES-1 cells,and secretion of NF-κB pathway effectors TNF-α,IL-6 and IL-8 were inhibited(P<0.05).After 2DG treatment,activity of NF-κB in GES-1 cells with TLR3,TLR4,TLR5,TLR6,TLR7,TLR8,TLR9 and TLR10 knockout were significantly decreased(P<0.05);while there was no significant changes in activity of NF-κB in TLR1 and TLR2 knockout GES-1 cells.Both TLR1 and TLR2 interactions were attenuated in GES-1 cells after 2DG treatment.Molecular docking showed that 2DG could bind to TLR2 amino acid disabled R321,K347 and F349,the binding energy was-12 kcal/mol.TLR2 wild-type and mutant plasmids(R321K,K347R,F349A)were constructed,and TLR2-knockout GES-1 cells were respectively transfected.It was found that 2DG treatment did not reduce NF-κB activity in GES-1 cells transfected with TLR2 mutant.Conclusion:Helicobacter pylori metabolite 2DG can interact with TLR2,reduce the formation of het-erodimers between TLR2 and TLR1,and inhibit the activity of innate immune NF-κB pathway.
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