Posttranslational sialylation and its impact on neutrophil recruitment.

Neutrophils are essential components of the innate immune system, playing a critical role in responding to infections and inflammation. Their recruitment from blood circulation to affected tissues follows a well-coordinated multistep adhesion and activation cascade. Recent studies highlight the importance of posttranslational modifications, particularly sialylation, in regulating neutrophil recruitment. Sialic acids, negatively charged monosaccharides, are attached to glycoproteins and glycolipids on neutrophil surfaces, influencing their stability, signaling, and interactions with endothelial cells. Selectins, key mediators of neutrophil rolling, recognize sialylated ligands such as sialyl Lewis-X on the neutrophil surface enabling the initial capture and rolling process. Additionally, sialylation of chemokine receptors and integrins modulate neutrophil activation and firm adhesion. Beyond recruitment, sialylation affects neutrophil homeostasis, aging, and clearance, as well as their interactions with pathogens and tumor cells. Dysregulation of sialylation has been linked to autoimmune diseases, cancer progression, and infections, making it an interesting target for therapeutic interventions. This review focuses on the functional role of posttranslational sialylation in neutrophil biology, detailing its impact on leukocyte recruitment, immune modulation, and potential therapeutic applications.