Gangliosides enhance M2-polarized macrophage elongation induced by IL-4 and IL-13

Abstract

Background: Macrophage polarization plays a crucial role in the immune response, and gangliosides regulate macrophage function. In this study, we investigated the role of gangliosides in modulating macrophage morphology and function in response to M2 polarization induced by interleukin (IL)-4 and IL-13.Methods: The mouse monocyte/macrophage cell line RAW264.7 and bone marrow macrophages were used to assess the role of gangliosides in macrophages. Additionally, St3gal5 knockdown was achieved using small interfering RNA constructs for further examinations.Results: Elongation of M2-polarized macrophages in the presence of IL-4 and IL-13 was associated with increased ganglioside synthesis, as shown by reverse transcription-polymerase chain reaction and immunoblot analyses. Pretreatment with D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol and St3gal5 knockdown significantly reduced elongation, indicating that gangliosides play a substantial role in this process. Flow cytometry revealed that ganglioside monosialodihexosylganglioside (GM3) and ganglioside disialodihexosylganglioside (GD3) expression was significantly upregulated in M2-polarized macrophages. Moreover, transwell migration assays demonstrated that GM3 promoted macrophage migration, and this effect was abrogated by St3gal5 knockdown. Despite increased elongation and migration, phagocytic activity was reduced in elongated macrophages, as measured by the phagocytosis index using latex beads, which was reversed upon St3gal5 knockdown. Additionally, GM3 treatment activated the protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) signaling pathways, as confirmed by immunoblot analysis, demonstrating their role in ganglioside-induced elongation.Conclusions: Our findings highlight the crucial role of gangliosides in regulating the morphological plasticity of macrophages via AKT and ERK activation to promote elongation, which results in increased migration and reduced phagocytosis. This study provides insights into the mechanism by which gangliosides influence macrophage function and immune responses.