Silkrose: A novel acidic polysaccharide from the silkmoth that can stimulate the innate immune response

Abstract

We have identified a novel acidic polysaccharide from silkmoth (Antheraea yamamai) pupae that activates the mammalian innate immune response. This bioactive polysaccharide was isolated using nitric oxide production in mouse RAW264 macrophages as an indicator of immunostimulatory activity. We named this polysaccharide "silkrose". It has a molecular weight of 3.15 × 10(5) and comprises nine monosaccharides. The expression profiles indicated that silkrose induced the expression of proinflammatory cytokines and interferon β that exist downstream of MyD88-dependent and MyD88-indeptendent signaling pathways. Also, the inhibition of Toll-like receptor 4 (TLR4), which exists upstream of the signaling pathways, led to the suppression of NO production by silkrose. Furthermore, this polysaccharide promoted the activation of nuclear factor kappa B in RAW264 cells, indicating that it stimulates the induction of various cytokines in macrophages through the TLR4 signaling pathway. Our results thus suggest that silkrose activates the innate immune response to various pathogenic microorganisms and viral infections.

The silkrose of Bombyx mori effectively prevents vibriosis in penaeid prawns via the activation of innate immunity

“…Eight of these monosaccharides were found to be common with those among the bioactive polysaccharides of A. yamamai and B. cucurbitae , but to differ in terms of molar ratios. We termed this newly identified polysaccharide ‘silkrose of B. mori ’ (silkrose-BM) after our previous finding of silkrose from A. yamamai pupae 9 .

Figure 2 Chromatogram of the purified polysaccharide of B. mori pupae on size-exclusive gel filtration chromatography.

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“… Species Molecular weight * EC 50 μg/mL pmol/mL B. mori 1,150,000 2.5 + 0.5 2.1 + 0.4 A. yamamai 315,000 0.0043 + 0.0029 0.014 + 0.009 E. coli O26 (LPS) N.D. 0.011 + 0.002 N.D. * The molecular weight of the polysaccharide isolated from A. yamamai is based on Ohta et al . 8 , 9 .

Figure 3 Total ion chromatogram of the purified polysaccharide of B. mori pupae.

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“…Insects remain a largely unused natural resource with great potential as they are a viable and attractive source of bioactive substances 1 – 3 and a sustainable source of both human food, and terrestrial and aquatic animal feed 4 – 7 . Recently, we identified novel bioactive polysaccharides from the pupae of the melon fly ( Bactrocera cucurbitae ) and Japanese oak silkmoth ( Antheraea yamamai ) 8 , 9 . These acidic polysaccharides, termed dipterose and silkrose, comprise nine monosaccharides and activate nitric oxide (NO) production and the expression of proinflammatory cytokines and interferon β via toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway in RAW264 murine macrophages 8 , 9 …”

“…Recently, we identified novel bioactive polysaccharides from the pupae of the melon fly ( Bactrocera cucurbitae ) and Japanese oak silkmoth ( Antheraea yamamai ) 8 , 9 . These acidic polysaccharides, termed dipterose and silkrose, comprise nine monosaccharides and activate nitric oxide (NO) production and the expression of proinflammatory cytokines and interferon β via toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway in RAW264 murine macrophages 8 , 9 …”

Polysaccharide from wheat bran induces cytokine expression via the toll-like receptor 4-mediated p38 MAPK signaling pathway and prevents cyclophosphamide-induced immunosuppression in mice

“…[4] In recent years, numerous polysaccharides isolated from natural resources have been demonstrated to possess a broad spectrum of therapeutic properties such as antioxidant, anti-cancer, and immune-modulating activities, and have been used widely in the food and pharmaceutical industries. [5–7] Several plant polysaccharides have been regarded as important immunostimulant candidates due to their ability to enhance the activation of macrophages with no significant side effects and low toxicity.…”