Fig. 2.

In endothelial cells, celiac patient immunoglobulin A (CD IgA) affects extracellular fibronectin and cross-links. The relative amount of a fibronectin as well as c the extent of N-ε(γ-l-glutamyl)-l-lysine cross-links were analyzed by a microtiter plate assay in HUVECs with no supplementation or after 24-h treatment in the presence of CD IgA and healthy IgA (H IgA). The results were normalized to HUVECs without any treatment, indicated by the dashed line. Bars represent the mean and error bars indicate standard error of the mean. A p value <0.05 was considered significant (*p < 0.05, **p < 0.01, and ***p < 0.001) and only statistically significant results are reported. Data derived from three independent experiments repeated in quadruplicate are shown. b Representative immunofluorescence stainings of fibronectin in live HUVECs alone or incubated for 24 h with H IgA and CD IgA. Scale bar 100 μM. d Representative immunofluorescence stainings of protein cross-links in control HUVECs with no treatment or incubated for 24 h with H IgA and CD IgA. Cross-links are shown in green and DAPI was used as nuclear counterstain (blue). Scale bar 50 μM. The extracellular TG2 activity was inhibited by administering a site-directed, non-permeable inhibitor, R281