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Evaluation of innate immune stimulating activity of polysaccharides using a silkworm (Bombyx mori) muscle contraction
T Fujiyuki1, H Hamamoto, K Ishii
1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Abstract:
In silkworm larvae, the mature form of paralytic peptide (PP), an insect cytokine, is produced from pro-PP in association with activation of innate immune responses, resulting in slow muscle contraction. We utilized this reaction, muscle contraction in silkworms coupled with innate immunity stimulation, to quantitatively measure the innate immune stimulating activity of various natural polysaccharides. β-Glucan of Gyrophora esculenta (GE-3), fucoidan from sporophyll of Undaria pinnatifida, and curldan induced silkworm muscle contraction. We further demonstrated that GE-3 had therapeutic effects on silkworms infected by baculovirus. Based on these findings, we propose that the silkworm muscle contraction assay is useful for screening substances that stimulate innate immunity before evaluating therapeutic effectiveness in mammals.
Insights
Researchers developed a silkworm muscle contraction assay to measure innate immune stimulating activity. This assay identified natural polysaccharides like beta-glucan (GE-3) that activate immunity and showed GE-3 has therapeutic potential against viral infections.
Area of Science:
- Immunology
- Entomology
- Natural Products Chemistry
Background:
- Innate immunity in insects, like silkworms, involves complex signaling pathways.
- Paralytic peptide (PP) production is linked to innate immune activation and subsequent muscle contraction in silkworms.
- Natural polysaccharides are known for their immunomodulatory properties.
Purpose of the Study:
- To establish a novel bioassay for quantifying innate immune stimulating activity using silkworm muscle contraction.
- To screen various natural polysaccharides for their ability to stimulate innate immunity in silkworms.
- To evaluate the therapeutic potential of identified immune-stimulating compounds.
Main Methods:
- Utilized silkworm larvae as a model system to measure muscle contraction triggered by innate immune stimulation.
- Quantitatively assessed the immune-stimulating activity of natural polysaccharides, including beta-glucan (GE-3), fucoidan, and curldan.
- Investigated the therapeutic efficacy of GE-3 in silkworms challenged with baculovirus infection.
Main Results:
- Silkworm muscle contraction was successfully induced by specific natural polysaccharides: GE-3, fucoidan, and curldan.
- Beta-glucan from Gyrophora esculenta (GE-3) demonstrated significant innate immune stimulating activity.
- GE-3 exhibited therapeutic effects against baculovirus infection in silkworms, indicating its potential as an antiviral agent.
Conclusions:
- The silkworm muscle contraction assay provides a robust method for screening innate immune stimulants.
- Natural polysaccharides, particularly GE-3, possess significant immunomodulatory and potential therapeutic properties.
- This assay serves as a valuable preliminary tool for identifying compounds with immune-boosting capabilities before mammalian studies.
