アルツハイマー病の原因がわかったー①

アルツハイマー病の原因がわかった

★アルツハイマー病の正体に迫るレポートをCBS Newsが伝えています。

「記事内容」

★タウ・プロテインがアルツハイマー病の正体か

「アルツハイマー病患者の脳内に見られるタウ・プロテインが次々と脳細胞に転移して、重度の認知症へと進行していくということが今回の調査で明らかになった。今回発表された神経変性脳疾患に対する新たなヒントのおかげで、科学者たちはアルツハイマー病の悪化を食い止める治療法を見つけることが出来るかもしれない。

２月１日に出版されたPLos Oneという雑誌に掲載された調査で、研究者たちは今回、マウスを使って実験を行った。マウスの遺伝子を異常タウ・プテインを含んだ人間の遺伝子に組み換え、タウ・プロテインの蓄積が始まると考えられている側頭葉ぷ分に埋め込んだ。そしてマウスの脳の状態を２か月以上にわたって分析し、プロテインの転移状況を調査した。その結果、マウスが成長するにつれて、タウ・プロテインがニューロンと他のニューロンとが信号を伝達し合うシナプス(神経細胞の接合部)を飛び越えて、脳内の様々な部分に転移していくことがわかった。

「これはアルツハイマー病の初期症状に極めて類似している。」と今回の調査研究者でコロンビア大学医療センター病理学教授のカレン・ダフ博士は語っている。

今回のマウスを使った実験結果により、様々な疑問点の解消に役立つとカレン・ダフ博士はニューヨーク・タイムズに話している。科学者たちはこれまでずっと、アルツハイマー病は何らかのメカニズムが働いて、脳内の細胞から細胞へと転移すると考えていたが、検死解剖やスキャン検査を行っても、そのメカニズムの解明には未だ結論が出されていいない状態だ。「これまでの調査方法は、交通事故で大破した車を見て、事故の原因を探ろうとするようなものだった。」とダフ博士は話している。

研究チームは今回の新しい発見がアルツハイマー病の治療の向上に用いられることを望んでいる。」

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Alzheimer's disease "jumps" across brain cells to spread (CBS) Alzheimer's disease spreads through the brain by jumping from one cell to another, according to a new study. The study found that tau protein, which indicates the fibrous tangles found in the brains of Alzheimer's patients, spreads along the brain's neurons from one region to the other - resulting in severe dementia. The new clues to the neurodegenerative brain disorder might help scientists find a way to stop the disease from getting worse. For the study - published in the Feb. 1 issue of PLoS One - researchers genetically modified mice to have a human gene for the abnormal tau protein in an area of the brain's temporal lobe where tau is thought to begin to accumulate. The researchers analyzed the mice brains over a 22-month period to map the protein's spread and found that as mice aged, the tau spread to different regions of their brains across synapses - the junctions neurons use to communicate with each other. "This pattern very much follows the staging that we see at the earliest stages of human Alzheimer's disease," senior study author Dr. Karen E. Duff, professor of pathology at the Columbia University Medical Center in New York City, said in a written statement. Duff told the New York Times that the mouse study answers many questions, since scientists had long thought the disease spread through some mechanism from one brain region to the other, but human autopsies and brain scan studies have been inconclusive. Duff told the paper that's because looking at brains of people who died with Alzheimer's is like "looking at a wrecked car and trying to find out the accident's cause." The study authors now hope their new findings can be used to improve treatments. "If, as our data suggest, tau pathology starts in the entorhinal cortex and emanates from there, the most effective approach may be to treat Alzheimer's the way we treat cancer - through early detection and treatment, before it has a chance to spread," study co-author Dr. Scott A. Small, professor of neurology at the Columbia University Medical Center, said in the statement. "It is during this early stage that the disease will be most amenable to treatment. That is the exciting clinical promise down the road." The findings may also provide new clues on how other neurodegenerative disorders, like Parkinson's spread, the New York Times reported. Dr. William Thies, chief medical & science officer at the Alzheimer's Association told CBS News that the findings are still early science, and it could take up to five years to really learn what the study's implications are. "If the speculation of these investigators is correct and you can find a way to interrupt the movement of tau from one neuron to another, that might be a useful therapeutic pathway," Thies told CBS News. "But there are many steps that have to come before you're actually going to get to a useful product that could be used to treat human disease." An estimated 5.4 million Americans live with Alzheimer's disease. Alzheimer's disease is the sixth leading cause of death in the U.S., according to the CDC's latest report, taking more than 83,000 lives this past year. (CBS News 2012/02/02)

タグ：アルツハイマー病