Polysaccharides isolated from Açaí fruit induce innate immune responses

Area of Science:

• Immunology
• Natural Product Chemistry

Background:

• Acai fruit is a popular supplement with purported immune-enhancing properties.
• Previous research focused on polyphenol fractions, with limited understanding of Acai's immune effects.
• Gamma delta (γδ) T cells are key immune cells responsive to plant-derived compounds.

Purpose of the Study:

• To investigate the immune-activating properties of Acai fruit fractions.
• To determine if Acai polyphenol or polysaccharide fractions activate γδ T cells.
• To characterize the innate immune responses induced by Acai polysaccharides.

Main Methods:

• Characterized γδ T cell responses to Acai polyphenol and polysaccharide fractions.
• Fractionated Acai polysaccharide preparation and tested activity in human peripheral blood mononuclear cells (PBMCs).
• Assessed myeloid cell recruitment and IL-12 production in vivo following Acai polysaccharide administration.

Main Results:

• Acai polyphenol fraction showed no significant immune activity.
• Acai polysaccharide fraction robustly stimulated γδ T cells in human, mouse, and bovine PBMC cultures.
• Larger Acai polysaccharides demonstrated the most potent in vitro activity.
• In vivo administration of Acai polysaccharide induced myeloid cell recruitment and IL-12 production.

Conclusions:

• Acai polysaccharides, not polyphenols, are responsible for activating innate immune cells, including γδ T cells.
• The study defines specific innate immune responses to Acai polysaccharides.
• Results indicate potential therapeutic implications for Acai polysaccharides in asthma and infectious diseases.