Immunomodulatory effects of polysaccharide compounds in macrophages revealed by high resolution AFM

Polysaccharide compounds (PCs), which composed of different kinds of polysaccharides always isolated from different kinds of traditional Chinese medicine, are now attracting more and more attentions due to their strong immunomodulatory activities beyond the corresponding one-component polysaccharides. In this study, we demonstrated for the first time that PCs-1 and PCs-2 had strong immunomodulatory effects on macrophages both in in vitro and in vivo models by atomic force microscopy (AFM). By high resolution AFM imaging, PCs-1 and PCs-2 were found to inhibit LPS induced cell surface particle size and roughness increase in RAW264.7 macrophages, demonstrating the anti-inflammatory effects of PCs-1 and PCs-2 on macrophages. PCs-1 and PCs-2 were also proved to increase the particle size and roughness of resting RAW264.7 macrophages, which suggested that PCs could activate resting RAW264.7 macrophages. And additionally, PCs-1 and PCs-2 were also found to reverse the surface particle size and roughness decrease of peritoneal macrophages isolated from cyclophosphamide induced immunosuppressive mice, suggesting the activation effects of PCs-1 and PCs-2 on immunosuppressive macrophages. These results further enhanced our understanding of macrophage activations by direct imaging of cell surface ultrastructure and also highlighted AFM as a novel nanotool for macrophage detections. And most importantly, these results also indicated the outstanding immunomodulatory effects of PCs on macrophages, which therefore suggested that PCs could be served as a kind of novel immunomodulatory agents that would benefit human health. SCANNING 38:792-801, 2016. © 2016 Wiley Periodicals, Inc.