Autoantibodies from patients with celiac disease inhibit transglutaminase 2 binding to heparin/heparan sulfate and interfere with intestinal epithelial cell adhesion
Autoantibodies from patients with celiac disease inhibit transglutaminase 2 binding to heparin/heparan sulfate and interfere with intestinal epithelial cell adhesion
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来自乳糜泻患者的自身抗体抑制转谷氨酰胺酶 2 与肝素/硫酸乙酰肝素的结合并干扰肠上皮细胞粘附
作者：
K. Teesalu;Marina Panarina;O. Uibo;R. Uibo;M. Utt
乳糜泻 (CD) 患者的自身抗体可以影响转谷氨酰胺酶 2 (TG2) 活性及其细胞功能，但确切机制仍不清楚。我们的目的是研究自身抗体是否可以调节 TG2 与肝素/硫酸乙酰肝素 (HS) 的结合以及肠上皮细胞与纤连蛋白-TG2 基质的附着。通过 TG2 亲和层析从活动性 CD 患者的血清中纯化抗 TG2 抗体。使用微孔板测定评估血清和抗体对 TG2 与肝素/HS 结合、TG2 转酰胺酶活性以及 Caco-2 细胞附着至纤连蛋白-TG2 基质的影响。与具有低抗 TG2 IgA 水平的 CD 患者或对照相比，来自具有高抗 TG2 IgA 水平的 CD 患者的血清和纯化的抗 TG2 抗体均减少了 TG2 与肝素/HS 的结合。抗 TG2 IgA 水平与 TG2 与肝素/HS 的结合呈负相关。与对照样品相比，用 CD 患者血清或纯化的抗 TG2 抗体处理纤连蛋白-TG2 包被的孔可减少 Caco-2 细胞在板上的附着。 CD 患者的抗体对 Caco-2 细胞粘附到纤连蛋白-TG2 基质的影响与含有 Arg-Gly-Asp 序列的肽对细胞粘附的抑制无关。抗TG2自身抗体对体外TG2转酰胺酶活性没有影响。我们认为，来自 CD 患者的自身抗体对 TG2 粘附功能的调节可能与抑制 TG2 与细胞表面蛋白聚糖的 HS 残基结合有关，并且可能对 CD 发病机制有影响。
Autoantibodies from patients with celiac disease (CD) can influence transglutaminase 2 (TG2) activity and its cellular functions, but the exact mechanisms have remained unknown. Our objective was to study whether autoantibodies could modulate TG2 binding to heparin/heparan sulfate (HS) and intestinal epithelial cell attachment to fibronectin-TG2 matrix. Anti-TG2 antibodies were purified by TG2 affinity chromatography from sera of patients with active CD. Serum and antibody effects on TG2 binding to heparin/HS, on transamidase activity of TG2, as well as on Caco-2 cell attachment to fibronectin-TG2 matrix were assessed using microplate assays. Both sera and purified anti-TG2 antibodies from CD patients with high anti-TG2 IgA levels reduced TG2 binding to heparin/HS as compared with those with low anti-TG2 IgA or controls. There was a negative correlation between anti-TG2 IgA levels and TG2 binding to heparin/HS. Treatment of fibronectin-TG2 coated wells with CD patients’ sera or purified anti-TG2 antibodies reduced attachment of Caco-2 cells onto the plate as compared with the control samples. The effect of CD patients’ antibodies on Caco-2 cell attachment to fibronectin-TG2 matrix occurred independently of the inhibition of cell adhesion by Arg-Gly-Asp sequence containing peptides. Anti-TG2 autoantibodies had no effect on transamidase activity of TG2 in vitro. We suggest that modulation of adhesion function of TG2 by autoantibodies from patients with CD could be related to the inhibition of TG2 binding to HS residues of cell surface proteoglycans and could have possible implications for CD pathogenesis.