圖片來源：the-scientist.com

　　腸道微生物組對機體健康非常關鍵，但一項對小鼠進行的研究卻發現，在涉及胰島素敏感性和肥胖症上，腸道微生物組或許並不像科學家們認為的那樣。

　　近日，一項刊登在國際雜誌NatureMedicine上的研究論文中，來自瑞士日內瓦大學的科學家通過研究表示，沒有腸道菌群的動物或許會表現出更好的葡萄糖耐受性和胰島素敏感性，而且還會表現出低脂肪低體重指數的情況。

　　研究者Mirko Trajkovski說道，盡管利用高劑量抗生素治療肥胖並不切實際，主要是由於抗生素耐受性出現的風險，但我們仍然像開發出一種可替代的方法來抑製或修飾微生物菌群，從而鑒別出對這種現象負主要責任（抗生素耐受性）的確切細菌；文章中研究者及其同事對小鼠進行研究，首先利用抗生素剔除消除腸道的菌群或者在無菌環境中飼養小鼠，隨後給予小鼠高脂肪飲食，當正常小鼠變得肥胖時，無菌小鼠還可以依然保持苗條，同時還會產生更多的米色脂肪（beige fat），即一種可以燃燒機體能量的脂肪組織。

　　研究結果表明，無菌小鼠機體中存在高水平的特定細胞因子，而抑製這種特殊信號或許就會損傷抗生素誘導的皮下脂肪褐變過程，同時還會抑製腸道菌群剔除小鼠的葡萄糖表型。後期研究中研究人員還將進行更為深入的研究來開發治療肥胖等疾病的新型療法。

　　doi:10.1038/nm.3994

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Microbiota depletion promotes browning of white adipose tissue and reduces obesity

　　Nicolas Suárez-Zamorano, Salvatore Fabbiano, Claire Chevalier, Ozren Stojanovi , Didier J Colin, Ana Stevanovi , Christelle Veyrat-Durebex, Valentina Tarallo, Dorothée Rigo, Stéphane Germain, Miroslava Ilievska, Xavier Montet, Yann Seimbille, Siegfried Hapfelmeier &Mirko Trajkovski

　　Brown adipose tissue (BAT) promotes a lean and healthy phenotype and improves insulin sensitivity1. In response to cold or exercise, brown fat cells also emerge in the white adipose tissue (WAT; also known as beige cells), a process known as browning2, 3, 4. Here we show that the development of functional beige fat in the inguinal subcutaneous adipose tissue (ingSAT) and perigonadal visceral adipose tissue (pgVAT) is promoted by the depletion of microbiota either by means of antibiotic treatment or in germ-freemice. This leads to improved glucose tolerance and insulin sensitivity and decreased white fat and adipocyte size in lean mice, obese leptin-deficient (ob/ob) mice and high-fat diet (HFD)-fed mice. Such metabolic improvements are mediated by eosinophil infiltration, enhanced type 2 cytokine signaling and M2 macrophage polarization in the subcutaneous white fat depots of microbiota-depleted animals. The metabolic phenotype and the browning of the subcutaneous fat are impaired by the suppression of type 2 cytokine signaling, and they are reversed by recolonization of the antibiotic-treated or germ-free mice with microbes. These results provide insight into the microbiota-fat signaling axis and beige-fat development in health and metabolic disease.