Page 247 - Haematologica April 2020

The role of neuraminidases in platelet function
the enzymes responsible for these changes, mammalian NEU (NEU1-4), have not been investigated in healthy platelets.
In this study, we did not discriminate between N- and O-linked glycans. Recent work has shown the importance of N-linked glycans in VWF-binding and its clearance.40,41
AB
Additionally, O-linked glycans have been implicated in both VWF-clearance42 and binding.43
On platelets, N- and O-linked glycans are covalently bound via asparagine residues and capped by sialic acid.2-4 The T-antigen (O-linked (sialic acid(α2-3)Gal-(β1-3)-[sialic acid(α2-6)]GalNAc) is present on VWF.44 O-linked glycans
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Figure 5. Effect of neuramidase-inhibition on agglutination, aggrega- tion and adhesion. (A) Agglutination was induced in washed platelets by VWF/risto ± pre-incubations with fibrinogen (Fg), RGDS and/or DANA (n=4). Data ± standard error of mean (SEM). *P<0.05 signifi- cant against VWF/risto, †: significant against control + DANA (one-way ANOVA). (B) PAC-1 binding in unstimulated washed platelets ± DANA (n=4). Results are shown as mean fluorescent intensities (MFI) values ± SEM. *P<0.05 significant against unstimulated (unstim) (paired t- test). (C) Aggregation of washed platelets induced by AA or collagen ± DANA (n=4 ± SEM). (D) Platelets were adhered to fibrinogen ± DANA pre-incubation. (E) Activity of recombinant neuramidase (NEU) (recNEU, 2.5-40 mU/mL, Clostridium) measured with and without (control) the presence of fibrinogen, collagen and D-dimer (500 μg/mL). Average emission was measured (590 nm) at each [recNEU] after 10 min.
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