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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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Intratracheal (i.t.) treatment with Acai-PS activates lung myeloid cells and induces IL-12 production in mice.BALB/c mice (n = 3) were treated i.t. with vehicle (dH20) or 500 µg Acai-PS in a volume of 100 µL. BALF and lung cells were isolated 24 h post-treatment. Cells were stained with antibodies for CD11b and CD11c and analyzed via flow cytometry for myeloid cell activation/recruitment. A) BALF alveolar macrophages were gated (autofluorescent/CD11c+; ovals) and activation was measured as an increase in mean CD11c-associated fluorescence within this gate. B) Cells in the lung interstitium were collected via collagenase extraction and similarly analyzed by FACS for myeloid cell recruitment/activation. The percentage of myeloid cells (rectangle gate) in relation to total live leukocytes was compared between Acai-PS and vehicle treated mice. Data from A) and B) are representative of three similar experiments and were repeated in C57BL/6 (3 experiments) and C3H/HeOuJ (2 experiments). C) BALF was collected from BALB/c mice provided varying dosages of Acai-PS i.t. Cells were removed by centrifugation, and IL-12(p70) concentration was determined in the supernatant fluid by cytokine ELISA.
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pone-0017301-g007: Intratracheal (i.t.) treatment with Acai-PS activates lung myeloid cells and induces IL-12 production in mice.BALB/c mice (n = 3) were treated i.t. with vehicle (dH20) or 500 µg Acai-PS in a volume of 100 µL. BALF and lung cells were isolated 24 h post-treatment. Cells were stained with antibodies for CD11b and CD11c and analyzed via flow cytometry for myeloid cell activation/recruitment. A) BALF alveolar macrophages were gated (autofluorescent/CD11c+; ovals) and activation was measured as an increase in mean CD11c-associated fluorescence within this gate. B) Cells in the lung interstitium were collected via collagenase extraction and similarly analyzed by FACS for myeloid cell recruitment/activation. The percentage of myeloid cells (rectangle gate) in relation to total live leukocytes was compared between Acai-PS and vehicle treated mice. Data from A) and B) are representative of three similar experiments and were repeated in C57BL/6 (3 experiments) and C3H/HeOuJ (2 experiments). C) BALF was collected from BALB/c mice provided varying dosages of Acai-PS i.t. Cells were removed by centrifugation, and IL-12(p70) concentration was determined in the supernatant fluid by cytokine ELISA.

Mentions: To determine if Acai-derived polysaccharides induce immune responses at mucosal surfaces, mice were treated i.t. with 500 µg Acai-PS and, 24 hrs later, cells in the BALF and lung tissue were extracted to measure myeloid cell activation/recruitment. In the BALF, alveolar macrophages (autofluorescent, Oval gate) increased expression of CD11c (Figure 7A), indicating these resident cells were activated. Similar to the peritonitis experiments, there was also a neutrophil influx detected in the BALF as shown by the increased CD11b+/CD11c− population (Figure 7A). These cells were likely neutrophils because of their high Gr-1 expression and distinctive light scatter profiles [data not shown]. The remaining lung tissue was then homogenized and collagenase digested to collect the lung interstitial population. Flow cytometry detected an additional CD11b/CD11c positive cell population (Figure 7B, rectangles). It is unknown from these experiments whether these additional myeloid cells were recruited or whether they were activated resident cells. Regardless of the source of these activated myeloid cells, these experiments demonstrate a change in lung innate immune cell profile upon Acai administration.


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)

Intratracheal (i.t.) treatment with Acai-PS activates lung myeloid cells and induces IL-12 production in mice.BALB/c mice (n = 3) were treated i.t. with vehicle (dH20) or 500 µg Acai-PS in a volume of 100 µL. BALF and lung cells were isolated 24 h post-treatment. Cells were stained with antibodies for CD11b and CD11c and analyzed via flow cytometry for myeloid cell activation/recruitment. A) BALF alveolar macrophages were gated (autofluorescent/CD11c+; ovals) and activation was measured as an increase in mean CD11c-associated fluorescence within this gate. B) Cells in the lung interstitium were collected via collagenase extraction and similarly analyzed by FACS for myeloid cell recruitment/activation. The percentage of myeloid cells (rectangle gate) in relation to total live leukocytes was compared between Acai-PS and vehicle treated mice. Data from A) and B) are representative of three similar experiments and were repeated in C57BL/6 (3 experiments) and C3H/HeOuJ (2 experiments). C) BALF was collected from BALB/c mice provided varying dosages of Acai-PS i.t. Cells were removed by centrifugation, and IL-12(p70) concentration was determined in the supernatant fluid by cytokine ELISA.
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Related In: Results  -  Collection

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pone-0017301-g007: Intratracheal (i.t.) treatment with Acai-PS activates lung myeloid cells and induces IL-12 production in mice.BALB/c mice (n = 3) were treated i.t. with vehicle (dH20) or 500 µg Acai-PS in a volume of 100 µL. BALF and lung cells were isolated 24 h post-treatment. Cells were stained with antibodies for CD11b and CD11c and analyzed via flow cytometry for myeloid cell activation/recruitment. A) BALF alveolar macrophages were gated (autofluorescent/CD11c+; ovals) and activation was measured as an increase in mean CD11c-associated fluorescence within this gate. B) Cells in the lung interstitium were collected via collagenase extraction and similarly analyzed by FACS for myeloid cell recruitment/activation. The percentage of myeloid cells (rectangle gate) in relation to total live leukocytes was compared between Acai-PS and vehicle treated mice. Data from A) and B) are representative of three similar experiments and were repeated in C57BL/6 (3 experiments) and C3H/HeOuJ (2 experiments). C) BALF was collected from BALB/c mice provided varying dosages of Acai-PS i.t. Cells were removed by centrifugation, and IL-12(p70) concentration was determined in the supernatant fluid by cytokine ELISA.
Mentions: To determine if Acai-derived polysaccharides induce immune responses at mucosal surfaces, mice were treated i.t. with 500 µg Acai-PS and, 24 hrs later, cells in the BALF and lung tissue were extracted to measure myeloid cell activation/recruitment. In the BALF, alveolar macrophages (autofluorescent, Oval gate) increased expression of CD11c (Figure 7A), indicating these resident cells were activated. Similar to the peritonitis experiments, there was also a neutrophil influx detected in the BALF as shown by the increased CD11b+/CD11c− population (Figure 7A). These cells were likely neutrophils because of their high Gr-1 expression and distinctive light scatter profiles [data not shown]. The remaining lung tissue was then homogenized and collagenase digested to collect the lung interstitial population. Flow cytometry detected an additional CD11b/CD11c positive cell population (Figure 7B, rectangles). It is unknown from these experiments whether these additional myeloid cells were recruited or whether they were activated resident cells. Regardless of the source of these activated myeloid cells, these experiments demonstrate a change in lung innate immune cell profile upon Acai administration.

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