北卡羅來納大學的Wei Jia教授與英國倫敦帝國學院的Jeremy Nicholson教授研究小組合作進行了一項國際研究，研究顯示，腸道內(nèi)的微生物可影響三聚氰胺中毒引起的腎臟疾病的嚴重程度。

2008年，近30萬中國兒童因食用受三聚氰胺（故意添加以提高蛋白質(zhì)含量）污染的奶粉引發(fā)腎臟疾病而住院。雖然已知三聚氰胺與尿酸結合，可在兒童體內(nèi)產(chǎn)生有害的腎結石，但其細節(jié)以及特異性腸道微生物的作用并沒有得到很明白。

通過研究三聚氰胺如何引起小鼠腎結石，研究小組的實驗結果顯示，腸道微生物可能對理解三聚氰胺引起的人腎功能衰竭非常重要。

當三聚氰胺與氰尿酸在腎臟發(fā)生反應形成血液中不溶的結晶時，就形成了腎結石。根據(jù)最近發(fā)表在《科學轉化醫(yī)學》上的一篇文章稱，某些種類的腸道菌群在三聚氰胺轉化為有毒的氰尿酸過程中發(fā)揮作用，從而加速腎結石形成的速度。

小鼠試驗表明，克雷伯氏菌家族微生物的存在可促進三聚氰胺的轉化，這使他們成為形成腎結石的主要參與者。這項研究表明，在這種情況下，毒性與受損組織的腸道菌群有關。

帝國學院外科與癌癥部的負責人，Nicholson 教授說，“腸道微生物的代謝活動在許多方面嚴重影響了人類健康，與涉及自身免疫性疾病，肥胖，糖尿病和心血管疾病的多種醫(yī)療問題有關”。“這項研究的特殊意義在于，中國受污染牛奶丑聞中出現(xiàn)的腎臟疾病可能是受累兒童的腸道細菌所介導。更具普遍的意義是，腸道微生物狀態(tài)影響環(huán)境和食品污染物暴露預后。”

Melamine poisoning has become widely publicized after a recent occurrence of renal injury in infants and children exposed to melamine-tainted milk in China. This renal damage is believed to result from kidney stones formed from melamine and uric acid or from melamine and its cocrystallizing chemical derivative, cyanuric acid. However, the composition of the stones and the mechanism by which the stones are formed in the renal tubules are unknown. We report that cyanuric acid can be produced in the gut by microbial transformation of melamine and serves as an integral component of the kidney stones responsible for melamine-induced renal toxicity in rats. Melamine-induced toxicity in rats was attenuated, and melamine excretion decreased after antibiotic suppression of gut microbial activity. We further demonstrated that melamine is converted to cyanuric acid in vitro by bacteria cultured from normal rat feces; Klebsiella was subsequently identified in fecal samples by 16S ribosomal DNA sequencing. In culture, Klebsiella terrigena was shown to convert melamine to cyanuric acid directly. Rats colonized by K. terrigena showed exacerbated melamine-induced nephrotoxicity. Cyanuric acid was detected in the kidneys of rats administered melamine alone, and the concentration after Klebsiella colonization was increased. These findings suggest that the observed toxicity of melamine may be conditional on the exact composition and metabolic activities of the gut microbiota.