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Issues

In recent years, with the improvement of residents' living standards, the dietary structure has become increasingly diverse. While foods such as seafood and beer provide a taste experience, they also hide health risks—these foods are rich in purine compounds. After being ingested by the human body, these compounds are absorbed in the intestines and finally converted into uric acid through metabolism, which enters the blood circulation. When the level of serum uric acid rises significantly and exceeds the body's physiological regulatory capacity, it will cause purine metabolism disorders, and in the long term, it can lead to hyperuricemia.

Gout is the most common complication of hyperuricemia. In the global health field, gout, as a high - incidence non - communicable disease, has become an important public health challenge. According to the 2024 report of the World Health Organization (WHO), the global prevalence of gout is approximately 3.9%, and the number of patients is showing a rapid growth trend: in 2020, there were about 55.8 million gout patients worldwide, with an age - standardized prevalence rate of 659.3 per 100,000 people; it is expected that by 2050, the number of patients will increase to 95.8 million, with an increase of more than 70%. Among them, the situation in East Asia is particularly severe. During the period from 1990 to 2020, the number of gout patients in this region increased by 175.9%, and the age - standardized prevalence rate increased by 26.4% during the same period.

Current Solution & Problems

Most traditional uric acid therapeutic drugs target the liver and kidneys. Although they have significant efficacy, they are often accompanied by severe side effects, as shown in the table below:

Fig1.The global prevalence distribution of gout

Research Foundation of Engineered Probiotics

The engineered probiotic YES301 previously developed by the SKLBE team was modified by introducing the xanthine transport gene XanQ from E. coli K - 12, followed by site - directed mutagenesis and promoter/RBS engineering. In an in vitro environment with a xanthine concentration of 150 μM, it can complete 83% of xanthine transport within 60 minutes, laying a foundation for the optimization of our strain.

Fig2.Construction of the YES301 plasmid and detection of purine transport capacity

Wet Lab

Given the continuous growth in the number of hyperuricemia patients and the limitations of current treatment methods, we are committed to developing a novel therapeutic regimen for hyperuricemia.

Through collaboration with the team led by Professor Zhou Ying from the State Key Laboratory of East China University of Science and Technology, we learned that although the engineered probiotic YES301 can initially achieve the transport of uric acid precursors, it still requires further optimization. By integrating feedback from stakeholders, we identified the core issues currently existing in engineered probiotics:

1.The biosafety of genetically modified (GM) products is prone to triggering public concerns;

2.Strains capable of only transporting uric acid precursors have limited therapeutic effects;

3.Existing strains lack carriers that enable targeted delivery to the intestines.

In response to the above issues, we designed corresponding experimental protocols and continuously verified their feasibility within the "Design-Build-Test-Learn (DBTL)" cycle.

For biosafety assurance, we adopted a "dual insurance" strategy: first, knocking out the smr resistance gene on the introduced plasmid to render the strain sensitive to commonly used antibiotics, thereby avoiding the risk of resistance gene dissemination; second, testing the gene transfer capability through plasmid passage experiments to ensure the strain exhibits reliable biosafety in both in vitro and in vivo environments. The modified strain was named YES302.

Fig1.The global prevalence distribution of gout

To enhance the therapeutic efficacy of the strain, we attempted to couple it with uric acid transport and degradation modules:

Uric Acid Transport Module: We screened three potential high-efficiency uric acid transporters (UacT, PucJ, and PucK). These transporters were then individually expressed in the chassis bacterium. Subsequent uric acid transport experiments led to the selection of UacT as the most efficient transporter, and the modified strain was named YES303. Additionally, we identified optimization targets for UacT via molecular docking and plan to optimize UacT expression in the chassis through promoter/RBS engineering.

Uric Acid Degradation Module: Simultaneously, we cloned and expressed the uricase gene derived from Bacillus cereus SKIII in the chassis bacterium after codon optimization. Structural optimization was further performed to enhance its secretion ability, resulting in the modified strain YES304, which demonstrated excellent uric acid degradation capacity.

We aim for the finally modified engineered probiotics to block intestinal absorption of uric acid precursors while enabling the transport and degradation of already formed uric acid, thereby significantly enhancing and expanding therapeutic effects. In the future, we plan to further optimize the strain to improve its uric acid degradation rate and functional protein secretion performance, and conduct the integration of functional gene modules.

In constructing the delivery system, we selected the pH-sensitive material Eudragit@L100-55 (an acrylic resin polymer that dissolves in environments with pH > 5.5) as the carrier. This material remains stable in gastric juice (pH < 3.0), protecting the engineered bacteria from gastric acid damage and ensuring their safe delivery to the intestines (pH> 5.5). However, experimental data indicate that the release efficiency of the engineered bacteria encapsulated by this material in the intestines needs improvement, which points out the direction for future optimization of the delivery system.

The development of YES series strains provides a substantial improvement to existing hyperuricemia treatment regimens and offers a reproducible framework and paradigm for the future development of drugs targeting other similar metabolic diseases. The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) define probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host." The engineered probiotics developed in this study fully comply with this definition, serving as strong evidence of innovative achievements in the health field. Its research concept is highly aligned with WHO's advocacy of "developing accessible, safe, and innovative treatment regimens for non-communicable diseases."

Model

Based on the experimental data and the Monod equation, we constructed a standard bacterial concentration model, which can accurately calculate the bacterial dose required for transporting the target amount of xanthine and hypoxanthine under specific experimental conditions. Considering the differences in purine transport efficiency among individuals, we further integrated key variables such as age, gender, and weight to establish an "intestinal purine - serum uric acid dynamic model". This model can simulate the growth dynamics of the engineered bacteria in the human intestine and the purine transport efficiency, and finally calculate the daily personalized intake of the engineered bacteria according to individual characteristics, effectively expanding the application scenarios of the experimental results.

$$\frac{dU}{dt}=\alpha \cdot k_2\cdot P(t)-U(t)\cdot [\beta +K_{\text{reabs}}\cdot (1-\frac{K_{\text{reabs}}}{K_{\text{reabs}}+\gamma \cdot \frac{B(t)}{B_{\text{ref}}}})]$$

In the future, we plan to incorporate more personalized parameters such as gastrointestinal digestion efficiency into the model variables to further improve the accuracy of dose calculation, with the expectation of providing support for clinical medication guidance.

Software/Hardware

1. Multilingual Intelligent Voice Assistant: A multilingual intelligent voice assistant was developed for hyperuricemia patients. In addition to providing popular science knowledge on disease prevention, it can also convert the food information input by users through voice into purine intake data with the help of natural language processing technology and combined with the official database of China Food Network. After program analysis, it calculates the specific content of xanthine and hypoxanthine in the food; then, by embedding the "intestinal purine - serum uric acid dynamic model", it can help users quickly obtain the personalized dosage of probiotic drugs.

2. Comprehensive Science Popularization and Communication Platform (Suprobiotics): We pioneered the establishment of a comprehensive science popularization and communication platform Suprobiotics for researchers and (potential) users in the global probiotic field. On the one hand, this platform provides probiotic science popularization content for the public, helping the public master the methods to identify the advantages and disadvantages of probiotic products, and at the same time recommends selected science popularization articles and reliable products; on the other hand, it invites professionals such as clinical doctors and university professors to answer the public's questions, ensuring the scientificity and credibility of the information. In addition, the platform also builds a cross - border communication community for researchers in the global probiotic field, facilitating academic cooperation and technology sharing. The establishment of this platform not only helps our engineered probiotics gain public recognition based on scientific evidence but also promotes the entire probiotic industry to develop in a more reliable and transparent direction.

Human Practice

The human practice team collected and integrated project evaluation opinions and optimization suggestions by issuing questionnaires and conducting interviews with stakeholders, providing important guidance for the experimental team to promote research and improve the protocol.

In terms of expanding community influence, in view of the public's concerns about live bacterial drugs and genetically modified products, as well as the lack of knowledge about synthetic biology, we carried out a variety of science popularization activities: we developed exclusive educational tools for groups with different ages, regions, and educational backgrounds, and implemented personalized and hierarchical science popularization promotion, which has received a wide range of social responses.

Our human practice work fully reflects the inclusive goal of "expanding the universal scope of synthetic biology": first, we identified the obstacles faced by the public in obtaining synthetic biology knowledge through extensive research and conducted in - depth dialogues with marginalized groups such as people with disabilities; we carried out science popularization activities in schools to cultivate teenagers' health awareness; we produced braille versions of promotional brochures for visually impaired people and adapted science popularization picture books into audio books to ensure that different groups can obtain project information equally. These initiatives are highly consistent with the concept of "inclusiveness of health information (with particular attention to marginalized groups)" emphasized by WHO.

In addition, we actively carried out cooperation with enterprises in the field of intestinal health, laying a solid foundation for the industrialization of the project results and promoting the transformation of scientific innovation into practical public health benefits.