Tears N-glycosylation of VKC patients
MALDI -TOF N- glycans analyses were performed in 23 VKC individual tear samples. A unique distinctive profile emerged from these patients (Figure 1B). Peaks at m/z 2605.3 and 2966.5 corresponded to biantennary monofucosylated structures bearing one and two sialic acids respectively, whereas the ions at m/z 3415.7 and 3776.9 matched monofucosylated triantennary structures bearing two and three sialic acids respectively. These two structures showed the fucose unit linked either to the chitobiose core and to the antennaryN- acetylglucosamine.
Interstingly, the ion at m/z 2792.4, related to the biantennary disialo structure, was more intense in VKC patiens compared to CTRL (Figure 1A). On the contrary, peaks corresponding to truncatedN- glycans at m/z 1907.0, 2081.0 and 2285.1 were two- or three-fold less intense than the corresponding ones in the CTRL. Statistical differences between VKC and CTRL in relative intensities of the peaks are shown in Figure 3a. Interestingly, in VKC glyco-profiles the ions corresponding to the sialylated structures are more abundant, whereas, bisected N- glycan series is less abundant.