Glucose-rich polysaccharide from dried 'Shixia' longan activates macrophages through Ca2+ and CR3-mediated MAPKs and PI3K-AKT pathways

Awater-soluble glucose-rich polysaccharide from dried 'Shixia' longan pulp (LPsx) has been isolated for the first time, and its structure and immuno-regulatory mechanism were studied. LPsx is a hetero-polysaccharide with the average molecular weight 4102 g/mol. It was mainly consisted of glucose (95.9%), and small proportions of arabinose (2.1%), galactose (1.0%), mannose (0.6%), and xylose (0.4%). As analyzed by NMR, LPsx was mainly composed of (1 -> 6)-alpha-D-glucose and (1 -> 6)-beta-D-glucose, branched with alpha-D-glucose-(1 ->. The immunomodulatory activity study showed that LPsx significantly increased the phagocytosis of macrophages, and strongly promoted the production of NO, IL-1 beta, IL-6 and TNF-alpha. Moreover, LPsx could inhibit the inflammatory response induced by lipopolysaccharide. The immuno-regulatorymechanism of LPsx was studied using RNA- sequencing and receptors activity analyses. It was found that LPsx induced macrophage activation via Ca2+ and CR3-mediated MAPKs and PI3K-AKT signaling pathways. The results would be helpful for revealing the health promoting mechanism of dried 'Shixia' longan in traditional Chinese medicine. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The water-soluble glucose-rich polysaccharide LPsx from dried 'Shixia' longan pulp has been isolated and studied for its structure and immuno-regulatory mechanism. LPsx showed immunomodulatory activity by enhancing macrophage phagocytosis and promoting the production of various inflammatory factors, while also inhibiting the inflammatory response induced by lipopolysaccharide. The mechanism of immuno-regulation was found to involve Ca2+ and CR3-mediated MAPKs and PI3K-AKT signaling pathways in macrophage activation.