幽门螺杆菌代谢物拮抗宿主先天免疫的机制研究

Mechanism of Helicobacter pylori metabolites antagonizing host innate immunity

目的:探讨幽门螺杆菌代谢物拮抗宿主先天免疫的潜在机制。方法:RNA测序及通路富集分析测定仅LPS刺激的胃黏膜细胞GES-1、LPS与幽门螺杆菌培养上清共同处理的GES-1细胞及未经处理的GES-1细胞。3KD超滤管过滤幽门螺杆菌培养上清,并以过滤的滤液(代谢物部分)和截留的溶液(蛋白部分)处理LPS刺激的GES-1细胞,检测NF-κB通路活性、NF-κB的磷酸化水平、NF-κB通路效应因子TNF-α、IL-6和IL-8的分泌水平。非靶向代谢质谱鉴定关键代谢物。结果:相较于仅LPS刺激的GES-1细胞,LPS与幽门螺杆菌培养上清共同处理后,多种基因的表达水平受到调控,并趋于未处理的GES-1细胞水平,主要存在于NF-κB通路。LPS与幽门螺杆菌培养上清共同处理后,NF-κB通路活性受到抑制(P<0.05)。幽门螺杆菌代谢物能够抑制NF-κB通路活性,抑制NF-κB磷酸化,抑制NF-κB通路效应因子TNF-α、IL-6和IL-8的分泌(P<0.05)。1、5和25μmol/L的幽门螺杆菌代谢物2-D-Glucopyranose(2DG)处理后,胃黏膜细胞GES-1中NF-κB通路活性均受到抑制,NF-κB磷酸化受到抑制,NF-κB通路效应因子TNF-α、IL-6和IL-8的分泌受到抑制(P<0.05)。2DG处理后,TLR3、TLR4、TLR5、TLR6、TLR7、TLR8、TLR9、TLR10敲除的GES-1细胞中NF-κB活性显著降低(P<0.05);而TLR1和TLR2敲除的GES-1细胞中NF-κB活性无显著变化。2DG处理后,GES-1细胞中TLR1和TLR2的相互作用均减弱。分子对接发现2DG能够与TLR2氨基酸残基R321、K347、F349结合,结合能为-12 kcal/mol。构建TLR2野生型和突变型质粒(R321K、K347R、F349A),并分别转染TLR2敲除的GES-1细胞,发现2DG处理并不能减少转染了TLR2突变型的GES-1细胞的NF-κB活性。结论:幽门螺杆菌代谢物2DG能够与TLR2相互作用,减少TLR2与TLR1异源二聚体的形成,抑制先天免疫NF-κB通路活性。

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 25μmol/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 TLR^(2) knockout GES-1 cells.Both TLR1 and TLR^(2) interactions were attenuated in GES-1 cells after 2DG treatment.Molecular docking showed that 2DG could bind to TLR^(2) amino acid disabled R321,K347 and F349,the binding energy was-12 kcal/mol.TLR^(2) wild-type and mutant plasmids(R321K,K347R,F349A)were constructed,and TLR^(2)-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 TLR^(2) mutant.Conclusion:Helicobacter pylori metabolite 2DG can interact with TLR^(2),reduce the formation of het-erodimers between TLR^(2) and TLR1,and inhibit the activity of innate immune NF-κB pathway.