Constitutive oxalate-biodegrading Bacillus subtilis for kidney stones

项目总结/摘要 肾结石（肾结石）是一种非常痛苦和衰弱的情况。关于 12%的人在一生中会经历肾结石，其中约70%会有 复发。肾结石的经济负担估计每年超过50亿美元 仅在美国。在美国，每年有超过300万个工作日因肾结石而损失。 75%的肾结石由草酸钙（CaOx）组成，是由过量的尿 草酸盐水平。 不幸的是，目前的治疗方案都有严重的缺点。一种低草酸饮食， 通常推荐用于CaOx结石患者，但其本身不是非常有效。碱化 诸如柠檬酸钾之类的药剂可以减少结石复发，但是昂贵并且经常引起 胃肠道不适。噻嗪类利尿剂经常出现可能危及生命的不良反应 例如低钾血症。因此，仍然有一个新的肾脏开发的强烈需求 安全有效的结石治疗方案。 我们建议开发和测试一种新的肾结石治疗方法，包括一种新的 过表达内源性草酸盐生物降解酶的枯草芽孢杆菌菌株。作为 细菌停留在肠道内，潜在的副作用范围大大减少， 与小分子药物相比，因此，我们的创新方法旨在实现 可负担得起的、安全的和广泛有效的肾结石治疗选择。 在第一阶段的SBIR项目中，我们将开发新的枯草芽孢杆菌菌株， 生物降解草酸盐。我们将生产和测试不同的菌株，以优化草酸 生物降解能力。因为我们将在染色体上过度表达内源性酶 我们的方法避免了以前开发的草酸盐细菌的主要缺点- 降解微生物。最后，我们将确定表现最好的工程菌株是否能 在相关大鼠模型中有效降低尿草酸水平。

Project Summary / Abstract Kidney stones (nephrolithiasis) are an extremely painful and debilitating condition. About 12% of people will experience kidney stones in their lifetime, and about 70% of those will have recurrences. The economic burden of kidney stones is estimated to exceed $5 billion per year in the USA alone. Each year, over 3 million workdays are lost in the USA due to kidney stones. 75% of kidney stones consist of calcium oxalate (CaOx), and are caused by excessive urinary oxalate levels. Unfortunately, current treatment options all have serious drawbacks. A low oxalate diet is routinely recommended for CaOx stone patients, but is not very effective by itself. Alkalinizing agents such as potassium citrate can reduce stone recurrence, but are costly and often cause GI distress. Thiazide diuretics come with frequent, potentially life-threatening adverse effects such as hypokalemia. Thus, there remains a strong need for the development of new kidney stone treatment options that are both safe and effective. We propose to develop and test a new kidney stone treatment consisting of a novel Bacillus subtilis strain that overexpresses endogenous oxalate biodegrading enzymes. As bacteria stay in the gut, the spectrum of potential side effects is massively reduced as compared to small molecule drugs. Thus, our innovative approach is designed to result in an affordable, safe, and broadly effective kidney stone treatment option. In this Phase I SBIR project, we will develop new Bacillus subtilis strains engineered to biodegrade oxalate. We will produce and test different strains to optimize oxalate biodegradation capacity. As we will chromosomally overexpress endogenous enzymes in a spore-forming bacterium, our approach avoids key drawbacks of previously developed oxalate- degrading microbes. Finally, we will determine if the best performing engineered strain can effectively reduce urine oxalate levels in a relevant rat model.