AUTHOR=Lan Haibo , Li Wu , Xu Jucai , Yang Yuzhe , Tan Zhaolun , Yang Ruili 

TITLE=A Novel Polysaccharide Isolated From Fresh Longan (Dimocarpus longan Lour.) Activates Macrophage via TLR2/4-Mediated PI3/AKT and MyD88/TRAF6 Pathways

JOURNAL=Frontiers in Pharmacology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2021.786127

DOI=10.3389/fphar.2021.786127

ISSN=1663-9812

ABSTRACT=<p>A novel immunomodulatory polysaccharide (LP4) with a molecular weight 6.31 × 10<sup>4</sup> g/mol was purified from fresh longan pulp. It was composed of mannose, glucose, glucuronic acid, galactose, xylose, arabinose, galacturonic acid, fucose, and rhamnose in a molar percentage of 36:31:10:7:4:4:3:2:2, and mainly linked by (1→6)-<italic>β</italic>-Man, (1→4)-<italic>β</italic>-Glc and (1→6)-<italic>α</italic>-Glc. LP4 can obviously enhance the phagocytosis of macrophages and promote the proliferation of lymphocytes. After treating macrophages with LP4 (12.5–50 μg/ml), the production of IL-1β and TNF-α was significantly increased. These increases of cytokines were suppressed when the TLR2/TLR4 receptors were inhibited by anti-TLR2 and/or anti-TLR4 antibodies. Moreover, the mRNA expression of INOS, AKT, PI3K, TRAF6 and MyD88 was significantly suppressed by TLR2/TLR4 antibodies. These results indicated that LP4 induced macrophage activation mainly <italic>via</italic> the TLR2 and TLR4-induced PI3K/AKT and MyD88/TRAF6 pathways.</p>