Purified active lotus plumule (Nelumbo nucifera Gaertn) polysaccharides exert anti-inflammatory activity through decreasing toll-like receptor-2 and -4 expressions using mouse primary splenocytes

Abstract

Ethnopharmacological significance: Lotus plumule is widely used as traditional Chinese medicine. Among the active components in lotus plumule, polysaccharides exhibit promising potential for its potent anti-inflammatory effects. However, the anti-inflammatory mechanism of purified polysaccharides from lotus plumule remains unknown. To evaluate their anti-inflammatory potential and possible mechanisms of purified polysaccharides in lotus plumule, two active lotus plumule polysaccharides, fractions F1 and F2, were subjected to assay their anti-inflammatory potential and possible mechanisms using murine primary splenocytes in the absence or presence of lipopolysaccharide (LPS).

Materials and methods: Two purified active lotus plumule polysaccharides, F1 and F2, were cultured independently with murine primary splenocytes in the absence or presence of LPS under four different experiment models in vitro. Changes in pro-inflammatory IL-1β, IL-6 and TNF-α, as well as anti-inflammatory IL-10 cytokines secreted by the treated splenocytes were determined using an enzyme-linked immunosorbent assay (ELISA). The amount of toll-like receptor (TLR)-2 and TLR-4 mRNA expression levels in the cells were quantitated using a two-step real-time polymerase chain reaction (PCR) assay.

Results: The results showed that F1 and F2 treatments alone, particularly F2, significantly (P<0.05) decreased pro-/anti-inflammatory (IL-1β/IL-10 and TNF-α/IL-10) cytokine secretion ratios dose-dependently. F1 and F2 treatments in the presence of LPS significantly decreased TLR-2 and/or TLR-4 mRNA expression levels in the splenocytes under inflammatory and repair experiment models.

Conclusions: The present study proved that F1 and F2 had strong anti-inflammatory effects through inhibiting TLR-2 and/or TLR-4 expressions in the splenocytes in normal, inflammatory and repair situations. Our results further suggest that F2, which is a glycoprotein with low molecular weight of 25.7 kDa, may serve as a promising lead for the development of selective TLR antagonistic agents for inflammatory diseases.