Hydrolyzed Konjac glucomannan suppresses IgE production in mice B cells.
BACKGROUND
Oral administration of pulverized Konjac glucomannan (KGM) reduces increased plasma IgE and the amount of epsilon-germline transcript (epsilonGT) in the spleen, as well as preventing the development of dermatitis in mice. To elucidate the mechanism of action of pulverized KGM, we solubilized KGM and studied its effect on IgE in vitro and in vivo.


METHODS
Solubilized KGM was prepared by acid hydrolysis, and we analyzed the effective molecular size for the suppression of IgE production and epsilonGT in vitro and the level of plasma IgE induced by immunization with ovalbumin in BALB/c mice.


RESULTS
The production of IgE and epsilonGT in splenic cells, but not purified B cells, was inhibited by hydrolyzed KGM (KGM hydrolyzed with 0.25 N HCl; H-KGM) at the optimal size of between 10 and 500 kDa. However, no effect was observed when H-KGM was substituted with unhydrolyzed KGM in vitro. IgE production from purified B cells cocultured with purified monocytes, but not with purified T cells, was inhibited by H-KGM. The release of IFNgamma in cultures of monocytes but in purified B cells with or without T cells was enhanced in the presence of H-KGM. Injection of mice with H-KGM also suppressed the production of plasma IgE and IgG1 but not IgG2a in vivo.


CONCLUSIONS
KGM at an optimal size prevents germline class-switching and IgE production both in vitro and in vivo. H-KGM may be useful as a tool to study the mechanism of action of KGM and as a dietary supplement to prevent atopic diseases.
Suzuki
Hidenori
H
Department of Dermatology, Division of Molecular Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Minami-ku, Hiroshima, Japan.
Oomizu
Souichi
S
Yanase
Yuhki
Y
Onishi
Nobukazu
N
Uchida
Kazue
K
Mihara
Shoji
S
Ono
Kazuhisa
K
Kameyoshi
Yoshikazu
Y
Hide
Michihiro
M
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D006868:Hydrolysis; D017578:Immunoglobulin Class Switching / Q000187:drug effects; D007073:Immunoglobulin E / Q000096:biosynthesis* / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007139:Immunoglobulin epsilon-Chains / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008351:Mannans / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010047:Ovalbumin / Q000276:immunology; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology
D016207:Cytokines; D007074:Immunoglobulin G; D007139:Immunoglobulin epsilon-Chains; D008351:Mannans; C022901:(1-6)-alpha-glucomannan; D007073:Immunoglobulin E; D007371:Interferon-gamma; D010047:Ovalbumin