Immune-modulation effect of Sargassum horneri polysaccharides on concanavalin A-stimulated splenocytes and allergic asthma mouse model

Abstract

Sargassum horneri (S. horneri) is an edible species of large brown algae inhabiting the coasts of northeastern Asia extensively. S. horneri has amino acids, polyphenols, and polysaccharides, that have various biological activities such as anti-oxidative, anti-inflammatory, immune-regulatory, anti-viral, and anticoagulant. However, their molecular immunological mechanisms are still unknown. This study investigated the curative effects of S. horneri polysaccharides (SHPS) on allergic asthma progression. First, we performed cell viability assays, LDH and 3H-thymidine incorporation of S. horneri on splenocytes to examine its cytotoxicity. There was no cytotoxic effects on concentrations 3.9 ~ 250 μg/mL of SHPS. SHPS increased the expression of toll-like receptors (TLRs) in splenocytes of ConA stimulation. SHPS reduced the production of transcription factors and cytokines involved in the differentiation of diverse Th cell types such as Th1 (IL-β, IFN-r, TNF-α), Th2 (IL-4, IL-10), and Th17 (IL-17A, IL-22) in ConA-stimulated splenocytes. Moreover, SHPS significantly decreased the abundance of B cells (CD19+CD45R/B220+) and macrophages (CD45+CD11b+) in ConA-stimulated splenocytes. In addition, SHPS suppressed TLRs expression and Th-type cytokines (Th1, Th2, and Th17) in lungs of PM-induced allergic asthma mice. The histopathological results confirmed that SHPS mitigated lung tissue inflammation and suppressed the hypersecretion of mucin in the PM-induced allergic asthma mouse model. The mucin secretion is regulated by genes such as MUC5AC, MUC5B, and SHPS reduced MUC2 in PM-induced allergic asthma mice. In this study, we provide a compelling rationale that SHPS may afford a promising approach for immunotherapy as an alternative for the treatment of allergic asthma induced by ambient PM.

Keywords: S. horneri polysaccharides (SHPS), concanavalin A (ConA), inflammation, asthma