Linear and branched beta(1-3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: Implications for dietary immunostimulation

Kudrenko, Ben, Snape, Natale and Barnes, Andrew C. (2009) Linear and branched beta(1-3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: Implications for dietary immunostimulation. Fish and Shellfish Immunology, 26 3: 443-450. doi:10.1016/j.fsi.2009.01.009


Author Kudrenko, Ben
Snape, Natale
Barnes, Andrew C.
Title Linear and branched beta(1-3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: Implications for dietary immunostimulation
Formatted title
Linear and branched ß(1-3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: Implications for dietary immunostimulation
Journal name Fish and Shellfish Immunology   Check publisher's open access policy
ISSN 1050-4648
1095-9947
Publication date 2009-03-01
Year available 2009
Sub-type Article (original research)
DOI 10.1016/j.fsi.2009.01.009
Open Access Status
Volume 26
Issue 3
Start page 443
End page 450
Total pages 8
Editor A. E. Ellis
C. J. Secombes
Place of publication Camden, London, U.K.
Publisher Academic Press
Language eng
Subject C1
070401 Aquaculture
830102 Aquaculture Fin Fish (excl. Tuna)
Abstract beta(1-3) glucans are a diverse range of carbohydrate polymers of differing lengths and structures that make up the cell walls of yeast, fungi, algae and some plants and activate innate immune responses in plants, invertebrates and higher animals. Consequently glucans are often used as dietary immunostimulants in commercial feeds for aquacultured fish species. The present study investigates the capability of purified glucans of differing structures and configurations, including curdlan, paramylon, laminarin and purified yeast 9 glucan to activate innate immunity in vitro using barramundi pronephros macrophages as a model, and compares them to Zymosan, a complex mixture derived from yeast cell walls, and lipopolysaccharide from Gram negative bacteria. All of the glucans were able to stimulate respiratory burst in barramundi macrophages at concentrations of 100 mu g/mL and 1000 mu g/mL, with curdlan eliciting the highest respiratory burst response at 1000 mu g/mL. LPS and Zymosan were the only immunostimulants tested that could prime barramundi macrophages by incubating with low concentrations (0.1 and 1 mu g/mL) for 24 h before triggering respiratory burst with PMA, suggesting teleost macrophages may not prime through the glucan receptor. As glucans are used as dietary immunostimulants, the pH of the barramundi stomach was assayed for 6 h following feeding and indicated that pH was as low as 2 for up to 6 h. Treating the glucans with dilute HCl at pH 2 completely neutralised their macrophage-activating capability. These results are important as they indicate that glucans do not prime barramundi macrophages but will activate them at high concentrations. However, it is debatable whether glucans will have any effect on macrophages if administered in the diet due to the combination of high concentration required and probable hydrolysis of the polymer structures as they pass through the acid environment of the stomach. (C) 2009 Elsevier Ltd. All rights reserved.
Formatted abstract
ß(1–3) glucans are a diverse range of carbohydrate polymers of differing lengths and structures that make up the cell walls of yeast, fungi, algae and some plants and activate innate immune responses in plants, invertebrates and higher animals. Consequently glucans are often used as dietary immunostimulants in commercial feeds for aquacultured fish species. The present study investigates the capability of purified glucans of differing structures and configurations, including curdlan, paramylon, laminarin and purified yeast ß glucan to activate innate immunity in vitro using barramundi pronephros macrophages as a model, and compares them to Zymosan, a complex mixture derived from yeast cell walls, and lipopolysaccharide from Gram negative bacteria. All of the glucans were able to stimulate respiratory burst in barramundi macrophages at concentrations of 100 μg/mL and 1000 μg/mL, with curdlan eliciting the highest respiratory burst response at 1000 μg/mL. LPS and Zymosan were the only immunostimulants tested that could prime barramundi macrophages by incubating with low concentrations (0.1 and 1 μg/mL) for 24 h before triggering respiratory burst with PMA, suggesting teleost macrophages may not prime through the glucan receptor. As glucans are used as dietary immunostimulants, the pH of the barramundi stomach was assayed for 6 h following feeding and indicated that pH was as low as 2 for up to 6 h. Treating the glucans with dilute HCl at pH 2 completely neutralised their macrophage-activating capability. These results are important as they indicate that glucans do not prime barramundi macrophages but will activate them at high concentrations. However, it is debatable whether glucans will have any effect on macrophages if administered in the diet due to the combination of high concentration required and probable hydrolysis of the polymer structures as they pass through the acid environment of the stomach.
Keyword Glucan
Bass dicentrarchus-iabrax
Innate immunity
Macrophages
Chemiluminescence
Immunostimulants
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Note: This article uses a German eszett "ß" character instead of the intended Greek beta "β" character in the title and throughout the article. This article's corrected title is "Linear and branched β(1–3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: Implications for dietary immunostimulation".

 
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Created: Thu, 03 Sep 2009, 18:14:00 EST by Mr Andrew Martlew on behalf of Centre for Marine Studies