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. 2019 May 22;11(5):1144.
doi: 10.3390/nu11051144.

Effects of Euglena gracilis EOD-1 Ingestion on Salivary IgA Reactivity and Health-Related Quality of Life in Humans

Ken-Ichi Ishibashi  1 , Machiko Nishioka  2 , Nobuteru Onaka  3 , Madoka Takahashi  4 , Daisuke Yamanaka  5 , Yoshiyuki Adachi  6 , Naohito Ohno  7
Affiliations

Effects of Euglena gracilis EOD-1 Ingestion on Salivary IgA Reactivity and Health-Related Quality of Life in Humans

Ken-Ichi Ishibashi et al. Nutrients. .

Abstract

Euglena gracilis EOD-1, a microalgal strain known for high yields of the β-1, 3-glucan paramylon, is suggested to function as a dietary fiber and enhance immunity. Here, we aimed to investigate the effects of E. gracilis EOD-1 biomass (EOD1BM) ingestion on immunoglobulin A (IgA) antibody titers in saliva, its reactivity, and the health-related quality of life (QOL) in humans. Reacting human immunoglobulin preparations and saliva with paramylon granules revealed the presence of anti-paramylon antibodies in the blood and saliva. We conducted a placebo-controlled, double-blind, crossover study involving 13 healthy subjects who ingested the placebo or EOD1BM for 4 weeks. Saliva was collected from each subject before and after ingestion, and IgA titers and E. gracilis EOD-1 paramylon (EOD1PM) reactivity were compared. In the EOD1BM Ingestion group, the anti-EOD1PM IgA content and titer increased after EOD1BM ingestion. No such change was observed in the Placebo group. Furthermore, the health-related QOL, especially mental health, increased in the EOD1BM Ingestion group. Thus, EOD1BM ingestion led to the production of paramylon (PM)-specific IgA antibody and increased salivary IgA antibody titers. We demonstrate that EOD1BM ingestion enhanced the immunity in the mucosal surface, evoked an antigen-specific response, and increased the health-related QOL, thereby contributing to health improvement.

Keywords: IgA; QOL; antibody; paramylon; β-1, 3-glucan.

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Conflict of interest statement

Three of the authors (M.N., N.O. (Nobuteru Onaka) and M.T.) are salaried employees of the Kobelco Eco-Solutions Co., Ltd. The remaining authors (K.-i.I., D.Y., Y.A., N.O. (Naohito Ohno)) have no conflict of interest to disclose. The food substance used in this study was provided by Kobelco Eco-Solutions Co., Ltd., and proper examination was performed by a third-party organization.

Figures

Figure 1
Figure 1
Test design. w: weeks. EOD1BM: Euglena gracilis EOD-1 biomass.
Figure 2
Figure 2
Binding of human immunoglobulin to Euglena gracilis EOD-1 paramylon (EOD1PM). (a) Reactivity of the anti-EOD1PM antibody. EOD1PM particles were blocked, reacted with polyglobin N, and analyzed by flow cytometry; (b) Specificity of the anti-EOD1PM antibody. EOD1PM particles were blocked, reacted with mixture of polyglobin N and competitive soluble antigen, and analyzed using flow cytometry. CSBG: solubilized cell wall glucan from Candida albicans; OVA: ovalbumin; sEOD1PM: solubilized EOD1 paramylon.
Figure 3
Figure 3
Binding of human saliva to Euglena gracilis EOD-1 paramylon (EOD1PM). (a) Reactivity of salivary anti-EOD1PM immunoglobulin A (IgA) antibody. EOD1PM particles were blocked, reacted with pooled human saliva, and analyzed by flow cytometry. (b) Specificity of salivary anti-EOD1PM IgA antibody. EOD1PM particles were blocked, reacted with a mixture of pooled human saliva and 100 µg/mL competitive soluble antigen, and analyzed using flow cytometry.
Figure 4
Figure 4
Class of antibody against Euglena gracilis EOD-1 paramylon (EOD1PM) in human sera and specific reactivities. (a) Reactivity of anti-sEOD1PM immunoglobulin (Ig) G, IgM, and IgA antibody in human sera. An ELISA plate was coated with solubilized EOD1PM (sEOD1PM) and blocked. Sera were diluted, and the amount of plate-bound Ig was determined using the detection antibody; (b) Specificity of the anti- sEOD1PM IgG antibody in human sera. An ELISA plate was coated with sEOD1PM and blocked. Human sera were mixed with serially diluted competitive soluble antigen and then applied to the ELISA plate. The amount of plate-bound Ig was determined using the detection antibody. AgHWE: Polysaccharide fractions from Agaricus brasiliensis; ASBG: solubilized cell wall glucan from Aspergillus niger.
Figure 5
Figure 5
Reactivity of antibody against Euglena gracilis EOD-1 paramylon (EOD1PM) in human saliva. (a) Reactivity of human salivary anti-sEOD1PM IgG, IgM, and IgA antibody. An ELISA plate was coated with sEOD1PM and blocked. Saliva samples were diluted, and the amount of plate-bound Ig was determined using the detection antibody. (b) Specificity of the human salivary anti-sEOD1PM IgA antibody. An ELISA plate was coated with sEOD1PM and blocked. Human saliva was mixed with serially diluted competitive soluble antigen and then applied to the ELISA plate. The amount of plate-bound Ig was determined using the detection antibody.
Figure 6
Figure 6
Reactivity of antibody against Euglena gracilis EOD-1 paramylon (EOD1PM) in saliva of healthy human volunteers. An ELISA plate was coated with sEOD1PM and blocked. Human saliva samples (n = 13) were diluted, and the amount of plate-bound Ig was determined using peroxidase-conjugated anti-human IgA antibody. Each column represents data from one individual.
Figure 7
Figure 7
Changes in anti-Euglena gracilis EOD-1 paramylon (EOD1PM) antibody titer after EOD1BM ingestion. The anti-EOD1PM antibody titer was measured by ELISA using sEOD1PM-coated plates (n = 7). The rate of increase in the titer was calculated using the following formula: Increase in anti-EOD1PM antibody titer (%) = ((anti-EOD1PM antibody titer after ingestion—anti-EOD1PM antibody titer before ingestion)/anti-EOD1PM antibody titer before ingestion) × 100. *: p < 0.05 (Mann–Whitney U test, n = 7). (a) Changes in anti-EOD1PM antibody titer after EOD1BM ingestion. (b) Changes in anti-OVA antibody titer after EOD1BM ingestion.
Figure 8
Figure 8
Effect of ingestion of Euglena gracilis EOD-1 biomass (EOD1BM) on health-related quality of life (QOL). (a) Influence of EOD1BM ingestion on the scores of the subscales of Medical Outcomes Study 36-Item Short Form version 2 (SF-36v2) (n = 7). A questionnaire survey from SF-36v2 was administered to the subjects after approximately 4 weeks of EOD1BM ingestion (n = 7). The scores before and after EOD1BM ingestion were analyzed and compared. *: p < 0.05, Wilcoxon signed-rank test (n = 7). (b) Effect of EOD1BM ingestion on SF-36v2 component summary score (n = 7). The component summary scores of Physical Component Summary (PCS), Mental Component Summary (MCS), and Role–Social Component Summary (RCS) based on the subscale scores before and after EOD1BM ingestion obtained by the administration of the SF-36v2 questionnaire were calculated. The rate of change before and after EOD1BM ingestion was calculated by the following formula: Pre–Post Component summary score ratio = Component summary score after ingestion/Component summary score ratio before ingestion. The changes before and after the ingestion within the group and the differences between the two groups were compared. *: p < 0.05, Mann–Whitney U test comparing the placebo and EOD1BM groups at the pre–post ratio (n = 7).
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