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Polysaccharides isolated from Açaí fruit induce innate immune responses.

Holderness J, Schepetkin IA, Freedman B, Kirpotina LN, Quinn MT, Hedges JF, Jutila MA - PLoS ONE (2011)

Bottom Line: Similar polyphenol and polysaccharide fractions are found in Acai fruit.Contrary to previous reports, we did not identify agonist activity in the polyphenol fraction; however, the Acai polysaccharide fraction induced robust γδ T cell stimulatory activity in human, mouse, and bovine PBMC cultures.When delivered in vivo, Acai polysaccharide induced myeloid cell recruitment and IL-12 production.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Infectious Diseases, Montana State University, Bozeman, Montana, United States of America.

ABSTRACT
The Açaí (Acai) fruit is a popular nutritional supplement that purportedly enhances immune system function. These anecdotal claims are supported by limited studies describing immune responses to the Acai polyphenol fraction. Previously, we characterized γδ T cell responses to both polyphenol and polysaccharide fractions from several plant-derived nutritional supplements. Similar polyphenol and polysaccharide fractions are found in Acai fruit. Thus, we hypothesized that one or both of these fractions could activate γδ T cells. Contrary to previous reports, we did not identify agonist activity in the polyphenol fraction; however, the Acai polysaccharide fraction induced robust γδ T cell stimulatory activity in human, mouse, and bovine PBMC cultures. To characterize the immune response to Acai polysaccharides, we fractionated the crude polysaccharide preparation and tested these fractions for activity in human PBMC cultures. The largest Acai polysaccharides were the most active in vitro as indicated by activation of myeloid and γδ T cells. When delivered in vivo, Acai polysaccharide induced myeloid cell recruitment and IL-12 production. These results define innate immune responses induced by the polysaccharide component of Acai and have implications for the treatment of asthma and infectious disease.

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Acai polysaccharides induce MyD88-independent neutrophil influx to the peritoneum.A) BALB/c mice were injected intraperitoneally with saline, Acai, or Yam-1. After 4 h, mice were euthanized, peritoneal cells collected, and total neutrophil counts measured by flow cytometry. Data represent the average total cell count from a minimum of four mice per treatment group and error bars represent the SEM. B) C57BL/6 or MyD88−/− mice of mixed ages (12–23 weeks) and sexes were injected i.p with Acai-PS (400 µg) or saline and neutrophil flux was measured as in A) without the use of FACS beads to estimate total cell counts. The data are representative of the mean percentage of neutrophils in the wash ± SD from a single experiment with 3–4 mice/group. p-values (Student's T test) for both figures are represented as: *<0.05, **<0.01, ***<0.005, ****<0.001.
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pone-0017301-g006: Acai polysaccharides induce MyD88-independent neutrophil influx to the peritoneum.A) BALB/c mice were injected intraperitoneally with saline, Acai, or Yam-1. After 4 h, mice were euthanized, peritoneal cells collected, and total neutrophil counts measured by flow cytometry. Data represent the average total cell count from a minimum of four mice per treatment group and error bars represent the SEM. B) C57BL/6 or MyD88−/− mice of mixed ages (12–23 weeks) and sexes were injected i.p with Acai-PS (400 µg) or saline and neutrophil flux was measured as in A) without the use of FACS beads to estimate total cell counts. The data are representative of the mean percentage of neutrophils in the wash ± SD from a single experiment with 3–4 mice/group. p-values (Student's T test) for both figures are represented as: *<0.05, **<0.01, ***<0.005, ****<0.001.

Mentions: Since Acai polysaccharides affect multiple cell types, we next sought to examine the combined effects of Acai-derived polysaccharides in vivo. To this end, we first examined their effect on the recruitment of neutrophils after intraperitoneal (i.p.) injection in mice. As shown in Figure 6A, Acai-PS induced neutrophil recruitment into the peritoneum, similar to LAL+ polysaccharides, Yam-1. Consistent with our previous report demonstrating a clear difference between Yam-1- and LPS-induced responses [2], the effect was not contingent upon MyD88 signaling (Figure 6B). Since MyD88−/− mice are documented to possess an atypical immune response [60], [61], no conclusions can be reliably drawn from the apparent reduction of peritonitis in MyD88−/− mice versus wild-type mice; it may be that there is a MyD88-dependent component to the full response or it may be due to strain differences. These results indicate that the in vitro immunostimulatory responses we observed toward Acai polysaccharides were preserved in vivo.


Polysaccharides isolated from Açaí fruit induce innate immune responses.

Holderness J, Schepetkin IA, Freedman B, Kirpotina LN, Quinn MT, Hedges JF, Jutila MA - PLoS ONE (2011)

Acai polysaccharides induce MyD88-independent neutrophil influx to the peritoneum.A) BALB/c mice were injected intraperitoneally with saline, Acai, or Yam-1. After 4 h, mice were euthanized, peritoneal cells collected, and total neutrophil counts measured by flow cytometry. Data represent the average total cell count from a minimum of four mice per treatment group and error bars represent the SEM. B) C57BL/6 or MyD88−/− mice of mixed ages (12–23 weeks) and sexes were injected i.p with Acai-PS (400 µg) or saline and neutrophil flux was measured as in A) without the use of FACS beads to estimate total cell counts. The data are representative of the mean percentage of neutrophils in the wash ± SD from a single experiment with 3–4 mice/group. p-values (Student's T test) for both figures are represented as: *<0.05, **<0.01, ***<0.005, ****<0.001.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046208&req=5

pone-0017301-g006: Acai polysaccharides induce MyD88-independent neutrophil influx to the peritoneum.A) BALB/c mice were injected intraperitoneally with saline, Acai, or Yam-1. After 4 h, mice were euthanized, peritoneal cells collected, and total neutrophil counts measured by flow cytometry. Data represent the average total cell count from a minimum of four mice per treatment group and error bars represent the SEM. B) C57BL/6 or MyD88−/− mice of mixed ages (12–23 weeks) and sexes were injected i.p with Acai-PS (400 µg) or saline and neutrophil flux was measured as in A) without the use of FACS beads to estimate total cell counts. The data are representative of the mean percentage of neutrophils in the wash ± SD from a single experiment with 3–4 mice/group. p-values (Student's T test) for both figures are represented as: *<0.05, **<0.01, ***<0.005, ****<0.001.
Mentions: Since Acai polysaccharides affect multiple cell types, we next sought to examine the combined effects of Acai-derived polysaccharides in vivo. To this end, we first examined their effect on the recruitment of neutrophils after intraperitoneal (i.p.) injection in mice. As shown in Figure 6A, Acai-PS induced neutrophil recruitment into the peritoneum, similar to LAL+ polysaccharides, Yam-1. Consistent with our previous report demonstrating a clear difference between Yam-1- and LPS-induced responses [2], the effect was not contingent upon MyD88 signaling (Figure 6B). Since MyD88−/− mice are documented to possess an atypical immune response [60], [61], no conclusions can be reliably drawn from the apparent reduction of peritonitis in MyD88−/− mice versus wild-type mice; it may be that there is a MyD88-dependent component to the full response or it may be due to strain differences. These results indicate that the in vitro immunostimulatory responses we observed toward Acai polysaccharides were preserved in vivo.

Bottom Line: Similar polyphenol and polysaccharide fractions are found in Acai fruit.Contrary to previous reports, we did not identify agonist activity in the polyphenol fraction; however, the Acai polysaccharide fraction induced robust γδ T cell stimulatory activity in human, mouse, and bovine PBMC cultures.When delivered in vivo, Acai polysaccharide induced myeloid cell recruitment and IL-12 production.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Infectious Diseases, Montana State University, Bozeman, Montana, United States of America.

ABSTRACT
The Açaí (Acai) fruit is a popular nutritional supplement that purportedly enhances immune system function. These anecdotal claims are supported by limited studies describing immune responses to the Acai polyphenol fraction. Previously, we characterized γδ T cell responses to both polyphenol and polysaccharide fractions from several plant-derived nutritional supplements. Similar polyphenol and polysaccharide fractions are found in Acai fruit. Thus, we hypothesized that one or both of these fractions could activate γδ T cells. Contrary to previous reports, we did not identify agonist activity in the polyphenol fraction; however, the Acai polysaccharide fraction induced robust γδ T cell stimulatory activity in human, mouse, and bovine PBMC cultures. To characterize the immune response to Acai polysaccharides, we fractionated the crude polysaccharide preparation and tested these fractions for activity in human PBMC cultures. The largest Acai polysaccharides were the most active in vitro as indicated by activation of myeloid and γδ T cells. When delivered in vivo, Acai polysaccharide induced myeloid cell recruitment and IL-12 production. These results define innate immune responses induced by the polysaccharide component of Acai and have implications for the treatment of asthma and infectious disease.

Show MeSH
Related in: MedlinePlus