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<<   作成日時 : 2011/01/03 01:40   >>

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画像 アレルギーや関節リウマチなどの自己免疫疾患は、ヨーグルトのバクテリアのような細菌を摂取することで防止できるようになるかもしれない。
 無害なクロストリジウムバクテリア46種をマウス齧歯類に与えると、制御性T細胞Tregが迅速に結腸に誘導されるとわかった。
 クロストリジウムには多くのタイプがあり、破傷風や多剤耐性クロストリジウム-ディフィシレなどは問題である。(Reuters)
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腸内細菌が体重を左右する
http://kurie.at.webry.info/201006/article_20.html
腸内細菌叢は「第二の遺伝子」
http://kurie.at.webry.info/201003/article_9.html
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腸内細菌:免疫異常を抑制、潰瘍性大腸炎の治療法に期待
http://mainichi.jp/select/science/news/20101224k0000m040099000c.html
 マウスの腸内に共生するある種の細菌が、免疫機能の異常を抑える細胞の数を増やすことを、東京大の本田賢也准教授(免疫学)らが突き止めた。免疫異常が原因の一つと考えられている潰瘍性大腸炎やクローン病の治療法につながる成果で、23日付の米科学誌サイエンス電子版に掲載された。【斎藤広子】
 ◇マウスで確認 東大チーム
 潰瘍性大腸炎とクローン病は、腸の粘膜に潰瘍ができる難病で、免疫機能の異常が関与していると考えられている。国内の患者数は潰瘍性大腸炎が約10万5000人、クローン病は約3万人。根本的な治療法はない。
 本田准教授らは、無菌環境で飼育したマウスの大腸では、免疫異常を抑えるT細胞の一種「Treg細胞」の数が通常のマウスの約3割しかないことを見つけた。無菌環境マウスにさまざまな腸内細菌を接種し調べたところ、クロストリジウム属の細菌を接種した場合に、通常マウスと同程度までこの細胞が増えた。クロストリジウム属の腸内細菌が多いマウスはこの細胞が多く、炎症性腸炎に抵抗性があることも分かった。
 クロストリジウム属の細菌は、ボツリヌス菌など有害なものもあるが、無害なものは人間の腸内に多数共生している。
 人間の場合も、潰瘍性大腸炎やクローン病の患者は健康な人に比べ、クロストリジウム属の腸内細菌が大幅に少ないという報告がある。本田准教授は「細菌のどの分子が免疫異常を抑える細胞を増加させるのか、詳しいメカニズムを解明し、治療薬の開発につなげたい」と話している。

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Bacteria trigger production of key immune cells
http://www.reuters.com/article/idUSTRE6BM3RJ20101223
SINGAPORE | Thu Dec 23, 2010 2:53pm EST

SINGAPORE (Reuters) - Allergies and autoimmune diseases such as rheumatoid arthritis could one day be prevented by consuming a type of bacteria, like probiotics taken in yoghurt, according to a study published on Friday.

The researchers fed mice with a family of bacteria and found that it triggered the production of certain white blood cells, called regulatory T cells.

"By increasing regulatory T cells, they will help suppress many of our allergies and autoimmune diseases," said one of the scientists, Kenya Honda, an immunology associate professor at the University of Tokyo.

Regulatory T cells are white blood cells that regulate the immune system and prevent it from excessive reactions.

When an immune system goes into an overdrive, it can cause allergies. It can also destroy healthy cells and tissues and cause autoimmune diseases like rheumatoid arthritis, psoriasis or scaly skin, and Crohn's disease.

Honda and colleagues, who published their findings in the journal Science, used antibiotics to flush all bacteria from the guts of a group of mice.

They later fed the rodents 46 species of harmless Clostridium bacteria and found that regulatory T cells quickly returned to their colons.

"The 46 strains were isolated from healthy, conventionally reared mice," Honda said by telephone. "And the strains were sufficient for the induction of regulatory T cells in their colons."

The researchers next fed the bacteria to normal mice and found that it produced elevated levels of regulatory T cells in their colons. These normal mice were also able to ward off some allergies and colitis, an autoimmune disease, Honda said.

"We fed the clostridium species to normal, conventionally reared mice ... they had more regulatory T cells in their colons and they were resistant to colitis and other allergies," he said.

Looking ahead, Honda said experts can study the possibility of including live Clostridium bacteria in fermented foods.

"We may be able to use live Clostridium species in probiotics, like in yoghurt. If you drink Clostridium species, you may be able to increase regulatory T cells in your intestines and your allergic responses will be taken care of," he said.

Probiotics are live micro-organisms that are believed to be good for their hosts.

There are many other strains of Clostridium and some are harmful, including one that causes tetanus and the Clostridium difficile, a drug-resistant superbug. But these were not in the cocktail of bacteria given to the mice.

(Reporting by Tan Ee Lyn; Editing by Alex Richardson)

------------------------------------------------------
Published Online 23 December 2010
Science DOI: 10.1126/science.1198469

Induction of Colonic Regulatory T Cells by Indigenous Clostridium Species

1. Koji Atarashi1,*,
2. Takeshi Tanoue1,*,
3. Tatsuichiro Shima2,
4. Akemi Imaoka2,
5. Tomomi Kuwahara3,
6. Yoshika Momose4,
7. Genhong Cheng6,
8. Sho Yamasaki7,
9. Takashi Saito7,
10. Yusuke Ohba9,
11. Tadatsugu Taniguchi1,
12. Kiyoshi Takeda5,
13. Shohei Hori8,
14. Ivaylo I. Ivanov10,
15. Yoshinori Umesaki2,
16. Kikuji Itoh4 and
17. Kenya Honda1,11,†

+ Author Affiliations

1. 1Department of Immunology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
2. 2Yakult Central Institute for Microbiological Research, Tokyo 186-8650, Japan.
3. 3Department of Molecular Bacteriology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan.
4. 4Department of Veterinary Public Health, The University of Tokyo, Tokyo 113-8657, Japan.
5. 5Laboratory of Immune Regulation, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan.
6. 6Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095--1781, USA.
7. 7Laboratory for Cell Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
8. 8Research Unit for Immune Homeostasis, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
9.
9Laboratory of Pathophysiology and Signal Transduction, Graduate School of Medicine, Hokkaido University, Sapporo 060-0815, Japan.
10. 10Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY 10032, USA.
11. 11Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Saitama 332-0012, Japan.

1. †To whom correspondence should be addressed. E-mail: kenya@m.u-tokyo.ac.jp
1. ?* These authors contributed equally to this work.

Abstract

CD4+ T regulatory cells (Tregs), expressing the Foxp3 transcription factor, play a critical role in the maintenance of immune homeostasis. Here, we show that in mice, Tregs were most abundant in the colonic mucosa. The spore-forming component of indigenous intestinal microbiota―particularly clusters IV and XIVa of the genus Clostridium―promoted Treg cell accumulation. Colonization of mice by a defined mix of Clostridium strains provided an environment rich in transforming growth factor--β (TGF-β) and affected Foxp3+ Treg number and function in the colon. Oral inoculation of Clostridium during the early life of conventionally reared mice resulted in resistance to colitis and systemic IgE responses in adult mice, suggesting a new therapeutic approach to autoimmunity and allergy.



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