口服表达尿酸氧化酶的乳酸乳球菌调控小鼠血尿酸水平

Oral gavage of Lactococcus lactis expressing urate oxidase regulates serum uric acid level in mice

摘要:

尿酸氧化酶(urate oxidase, Uox)是尿酸代谢的关键酶，已经用于人高尿酸血症(hyperuricemia, HUA)的治疗。然而，异源性尿酸氧化酶进入血液会引发免疫排斥反应产生抗体，影响疗效。本研究采用食品级益生菌乳酸乳球菌(Lactococcus lactis) NZ9000为底盘细胞，构建了表达黄曲霉源尿酸氧化酶的工程菌(NZ9000-aUox)和“恢复”活性的人源尿酸氧化酶的工程菌(NZ9000-hUox)。结果表明，表达外源尿酸氧化酶的工程菌可在体外降低尿酸，并具有时间依赖性。进一步利用酵母膏成功诱导小鼠血尿酸升高，在第7天和第14天灌胃给予酵母膏的小鼠血尿酸均值分别升高85.4%和106.2%；同时工程菌NZ9000-aUox给药组小鼠血尿酸仅分别升高39.5%和48.3%，NZ9000-hUox给药组小鼠血尿酸分别升高57.0%和82.9%，证明工程菌能明显抑制血尿酸的升高。将效果更加显著的工程菌NZ9000-aUox与高尿酸血症一线治疗药物别嘌醇进行安全性比较，结果显示工程菌的肝脏安全性与别嘌醇相当，肾脏安全性优于别嘌醇，不仅能够缓解血尿酸升高导致的肾损伤，还能够避免别嘌醇治疗过程中可能引发的肾损伤加重的风险。本研究为高尿酸血症的长期治疗和调控提供了一种有效并且更加安全的治疗方法。

Abstract:

Urate oxidase (Uox) plays a pivotal role in uric acid (UA) degradation, and it has been applied in controlling serum UA level in clinical treatment of hyperuricemia (HUA). However, because Uox is a heterogenous protein to the human body, the immune rejections typically occur after intravenous administration, which greatly hampers the application of Uox-based agents. In this study, we used Lactococcus lactis NZ9000, a food-grade bacterium, as a host to express exogenous Uox genes, to generate the Uox-expressing engineered strains to treat HUA. Aspergillus flavus-derived Uox (aUox) and the “resurrected” human-derived Uox (hUox) were cloned into vector and expressed in NZ9000, to generate engineered strains, respectively. The engineered NZ9000 strains were confirmed to express Uox and showed UA-lowering activity in a time-dependent manner in vitro. Next, in an HUA mice model established by oral gavage of yeast paste, the UA levels were increased by 85.4% and 106.2% at day 7 and day 14. By contrast, in mice fed with NZ9000-aUox, the UA levels were increased by 39.5% and 48.3% while in mice fed with NZ9000-hUox were increased by 57.0% and 82.9%, suggesting a UA-lowering activity of both engineered strains. Furthermore, compared with allopurinol, the first-line agent for HUA treatment, mice fed with NZ9000-aUox exhibited comparable liver safety but better kidney safety than allopurinol, indicating that the use of engineered NZ9000 strains not only alleviated kidney injury caused by HUA, but could also avoided the risk of kidney injury elicited by using allopurinol. Collectively, our study offers an effective and safe therapeutic approach for HUA long-term treatment and controlling.