The participation of sialic acids in microglia–neuron interactions

Since it is known that sialic acid participates in neuronal plasticity, it is resonable to investigate its role in microglia–neuron interactions. In this study, we tested the effects of enzymatic removal of sialic acid on neurite and cell body density in microglia–neuron co-cultures. Additionaly, we analyzed the expression of Siglec-F protein, putative receptor for sialic acids, in microglial cells as well as its affinity to neurons. The results showed that removal of sialic acids affects neuronal integrity and changes microglial morphology. In presence of microglial cells, endoneuraminidase and α-neuraminidase significantly reduced neurite density (p < 0.05). Endoneuraminidase (p < 0.05) and α-neuraminidase (p > 0.05) decreased the number of neuronal cell bodies in comparison to control co-cultures. Neuraminidases-treated neurons showed reduced binding of Siglec-F protein, which we found in microglial cells. Our results suggest that interactions between sialic acids and Siglec receptors may protect neuronal integrity during neurodegenerative processes.