Jos Jansen

120 Chapter 5 Next, we aimed to gain more insight in desialylation with QTOF-MS. QTOF-MS provides additional detail on glycan composition. To investigate desialylation we used the combined abundance of the trisialo and the fucosylated trisialo TF isoform. Comparison of these combined peaks among the three groups only showed a slight statistically significant difference between the LTx and CLD groups (Supp. Table 2). However, because of the broad standard deviations we conclude that overall desialylation is not different between LTx candidates, CLD patients and healthy controls. In conclusion, based on these data, desialylation is more prominent in LTx candidates when measured with tIEF, but this data is not reproduced with QTOF-MS. Hyperfucosylation is more pronounced in end-stage liver disease than in chronic liver disease Hyperfucosylation of liver derived proteins is a known phenomenon in a variety of liver diseases. Therefore, we calculated the fucosylation ratio for the trisialo and pentasialo TF isoforms. (Figure 4 and Supp. Table 2). Fucosylation of the tetrasialo TF isoform was not reliably detectable because of overlap with other nearby peaks. Figure 4 shows that the ratios are higher for the LTx samples compared to the HC and the CLD samples (p < 0.0001 for both). These data indicate that hyperfucosylation of TF is more pronounced in end-stage liver disease compared to chronic liver disease and healthy controls. Figure 4. Boxplots of the fucosylation ratio of the tri- and pentasialo QTOF-MS isoforms. The left graph shows the fucosylation ratio of trisialotransferrin, or peak 79266. The right graph shows the fucosylation ratio of pentasialotransferrin, or peak 80211. We used a Kruskal-Wallis test for calculation of p-values. HC=healthy controls, CLD=chronic liver disease, LTx=liver transplantation