日本研究人員日前報告說，一種變異鏈球菌會使腦出血的風險增高約3倍。這一發現將有助于開發預防和治療腦出血的藥物。
（圖片來自文章）
日本大阪大學等機構的研究人員在新一期英國《自然—通訊》雜志上報告說，生活在口腔中的變異鏈球菌會導致蛀牙，60%至70%的日本人都攜帶這種細菌。研究人員還發現，約有8%的日本人攜帶一種含膠原蛋白的特殊變異鏈球菌。但在腦出血患者中，約有30%的人攜帶這種變異鏈球菌。由此推算，攜帶這種變異鏈球菌的人，其腦出血發病風險比其他人高出約3倍。
在動物實驗中，研究人員用一種特殊設備破壞實驗鼠的腦血管使其出血，并從人類腦出血患者唾液中采集這種變異鏈球菌投放到這些實驗鼠的血管中。結果發現，投放變異鏈球菌的實驗鼠的腦血管出血量比對照組實驗鼠多五六倍。研究人員發現，這種變異鏈球菌的膠原蛋白會富集到血管破損處，妨礙血管修復，從而導致出血增加。
研究人員說，健康人攜帶此類變異鏈球菌并無太大問題，但對于高血壓患者、吸煙者等血管較脆弱的人群，就容易引發腦出血。研究人員提醒這些“脆弱”人群更加注意養成健康生活習慣，警惕腦出血的發生。（生物谷 Bioon.com）
doi:10.1038/ncomms1491
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The collagen-binding protein of Streptococcus mutans is involved in haemorrhagic stroke
Kazuhiko Nakano; Kazuya Hokamura; Naho Taniguchi; Koichiro Wada; Chiho Kudo; Ryota Nomura; Ayuchi Kojima; Shuhei Naka; Yoshinori Muranaka; Min Thura; Atsushi Nakajima; Katsuhiko Masuda; Ichiro Nakagawa; Pietro Speziale; Nobumitsu Shimada; Atsuo Amano; Yoshinori Kamisaki; Tokutaro Tanaka; Kazuo Umemura; Takashi Ooshima
Although several risk factors for stroke have been identified, one-third remain unexplained. Here we show that infection with Streptococcus mutans expressing collagen-binding protein （CBP） is a potential risk factor for haemorrhagic stroke. Infection with serotype k S. mutans, but not a standard strain, aggravates cerebral haemorrhage in mice. Serotype k S. mutans accumulates in the damaged, but not the contralateral hemisphere, indicating an interaction of bacteria with injured blood vessels. The most important factor for high-virulence is expression of CBP, which is a common property of most serotype k strains. The detection frequency of CBP-expressing S. mutans in haemorrhagic stroke patients is significantly higher than in control subjects. Strains isolated from haemorrhagic stroke patients aggravate haemorrhage in a mouse model, indicating that they are haemorrhagic stroke-associated. Administration of recombinant CBP causes aggravation of haemorrhage. Our data suggest that CBP of S. mutans is directly involved in haemorrhagic stroke.
