Lipopolysaccharide changes sialylation pattern in the mouse central nervous system.

Sialylated glycoconjugates seem to play crucial role in the mechanisms that control the most important functions of the body. Sialylation is an important mechanism for the regulation of intercellular interactions that underlie neuronal plasticity as well as immune defense in the central nervous system (CNS). In this study, we analyzed the effect of lipopolysaccharide (LPS) on sialylation pattern in several regions of CNS. Additionally, we tested the effects of inflammatory stimulation on Siglec-F expression in microglial cells. Using lectin blotting with Maackia amurensis and Sambucus nigra agglutinins and immunostaining with antibody directed against PSA-NCAM we demonstrated altered expression of sialylated glycoconjugates differentially due to LPS-induced inflammation. We found that LPS caused significant increase of α2,3- and α2,6-linked sialic acids in the hippocampus and spinal cord. In the prefrontal cortex, the level of α2,3-linked sialic acids in selected glycoconjugates tended to be increased (p>0.05), while α2,6-linked sialic acids were reduced (p<0.05), while the expression of PSA-NCAM in all analyzed structures were significantly higher in comparison to the control group. The expression of Siglec-F in microglial cells stimulated with LPS remained unchanged. Given the significance of glycans in the brain biology we can conclude that sialic acids and their receptors Siglec may be crucial regulators of immune response in the CNS.