Project Description

Background

1.1 The Metabolic Disease Pandemic and Therapeutic Frontiers

The 21st century is defined by a global pandemic of metabolic disease. An estimated 2.5 billion adults were overweight or obese as of 2022, with projections suggesting this could reach 3.8 billion by 2050[1]. Over 589 million people currently live with diabetes mellitus, a number projected to rise to 853 million by 2050[2]. Type 2 Diabetes Mellitus (T2DM), a condition rooted in complex interactions between genetics, lifestyle, and environment, accounts for approximately 90-95% of diabetes cases[3,4] and drives staggering healthcare costs and immense human suffering. T2DM is characterized by two core defects: a progressive loss of insulin sensitivity in peripheral tissues (insulin resistance) and a subsequent failure of pancreatic beta-cells to compensate with adequate insulin secretion[5].

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T2DM Development[23]

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Global Obesity Trends

The pharmaceutical response to this crisis has culminated in the development of Glucagon-like peptide-1 (GLP-1) receptor agonists, such as semaglutide[6]. These drugs have demonstrated unprecedented efficacy in both glycemic control and weight management. However, their utility is severely constrained by prohibitive costs, a subcutaneous injection-based delivery model, and a significant burden of systemic side effects. These limitations arise directly from the pharmacological strategy employed: delivering a modified, long-acting peptide with a C18 fatty acid chain that creates sustained albumin binding, resulting in a half-life of approximately seven days and producing a sustained, high-concentration, and systemic activation of GLP-1 receptors—a state that is profoundly different from the body's natural physiology[6,7].

1.2 The Pathophysiology of T2DM

T2DM and obesity are not simply diseases of high blood sugar or excess weight; they are manifestations of systemic metabolic dysregulation.

Molecular Insights - Insulin Resistance

In a healthy individual, the hormone insulin acts as a key signal, instructing cells in muscle, liver, and adipose tissue to take up glucose from the bloodstream. In the state of insulin resistance, these tissues become less responsive to insulin's signal. The mechanisms are multifactorial and include chronic low-grade inflammation, with excess adipose tissue (particularly visceral fat) secreting pro-inflammatory cytokines like TNF-α and IL-6, which can interfere with insulin signaling pathways within cells[8]. Other conditions such as lipotoxicity and Endoplasmic reticulum stress are strongly linked to the inhibition of insulin receptor signaling[9-10].

Beta-Cell Dysfunction

Initially, the pancreatic beta-cells compensate for insulin resistance by increasing insulin production (hyperinsulinemia). However, over time, this chronic overwork, combined with the toxic effects of high glucose and lipid levels, leads to beta-cell exhaustion and apoptosis. This progressive decline in insulin-secreting capacity is the tipping point where impaired glucose tolerance transitions to overt T2DM[11].

1.3 A Dissection of Glucagon-Like Peptide-1

The therapeutic potential of GLP-1 stems from its natural role as a central regulator of glucose homeostasis.

Natural GLP-1 Biology

GLP-1 is an incretin hormone, secreted from the gut in response to nutrient ingestion and enhances insulin secretion. It is produced from the proglucagon gene, which is expressed in both pancreatic alpha-cells and intestinal enteroendocrine L-cells[12].

Upon binding to its G-protein coupled receptor (GPCR) on pancreatic beta-cells, GLP-1 triggers a signaling cascade that increases intracellular cyclic AMP (cAMP). This sensitizes the beta-cell to glucose, amplifying glucose-stimulated insulin secretion. Crucially, this effect is glucose-dependent; GLP-1 does not stimulate insulin release when blood glucose is normal or low, which confers a very low intrinsic risk of hypoglycemia. Beyond the pancreas, GLP-1 slows gastric emptying, suppresses hepatic glucose production (by inhibiting glucagon), and acts on hypothalamic neurons to promote satiety and reduce appetite[13].

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GLP-1 Functionalities[13]

The Pharmacological Hurdle

Native GLP-1 is a poor therapeutic agent due to its extremely short biological half-life of approximately 1.5-3 minutes (some sources report approximately 2 minutes). It is rapidly inactivated by the enzyme Dipeptidyl Peptidase-4 (DPP-4), which is widely expressed, including on the surface of endothelial cells, and is quickly cleared by the kidneys[14,15].

Engineering GLP-1 Analogs

Pharmaceutical science overcame this limitation with two key strategies, exemplified by semaglutide: DPP-4 resistance through amino acid substitution at position 8 (alanine to α-aminoisobutyric acid), which sterically hinders the DPP-4 enzyme and prevents proteolytic cleavage; and extended half-life through attachment of a C18 fatty diacid side chain via a linker to lysine-26 (acylation), which allows the drug to reversibly bind to serum albumin[7]. This albumin-bound state acts as a circulating reservoir, protecting the drug from renal filtration and dramatically extending its half-life to approximately one week (about 165-184 hours)[6].

This feat of protein engineering, however, creates the pharmacological state responsible for side effects: a constant, high-level systemic exposure that activates GLP-1 receptors non-physiologically across the entire body, leading to persistent gastrointestinal distress and off-target effects in the central nervous system and other organs[16].

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GLP-1 Analogs[7]

Our team presents Fleur — an oral delivery system that uses engineered probiotic bacteria to express and secrete wild-type GLP-1 within the gastrointestinal tract, delivered via a yogurt-based drink. Fleur aims to combine the therapeutic benefits of GLP-1 with the natural advantages of probiotics to provide a safer, more affordable, and more accessible option for metabolic health management.

Limitations of Injectable GLP-1 Therapies

The contemporary market for metabolic disease management reveals critical accessibility barriers:

  • Cost barriers: Typical monthly treatment is expensive and inaccessible for many patients
  • Side effects: Nausea, diarrhea, abdominal pain, and rare but serious adverse events including pancreatitis, kidney injury, and gastroparesis
  • Administration challenges: Injectable delivery creates adherence barriers and storage requirements
  • Systemic exposure: Long half-life increases risk of adverse events throughout the body
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Price levels of obesity treatment per Month

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Side Effects of Some Current Weight Loss Treatments[24]

The GLP-1 Opportunity

GLP-1 (Glucagon-Like Peptide-1) is an incretin hormone that enhances insulin secretion, reduces glucagon, slows gastric emptying, and promotes satiety. It may also confer cardio- and neuro-protective effects. However, native GLP-1 has a very short half-life (approximately 1.5–3 minutes) due to rapid DPP-4 (dipeptidyl peptidase-4) degradation, limiting its therapeutic potential.

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GLP-1 Mechanisms[26]

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GLP-1 Effects[25]

Our Solution: Engineered Probiotic GLP-1 Expression

Biological Innovation

Fleur represents a paradigm shift in peptide therapeutic delivery through synthetic biology:

[1] Bacterial Engineering

Selected probiotic strains (Lactobacillus plantarum and L. acidophilus) engineered to express and secrete wild-type GLP-1 in the gut.

[2] Localized Delivery

Producing GLP-1 in the GI tract minimizes systemic exposure while maximizing efficacy.

[3] Sustained Release

Probiotic colonization supports prolonged, physiologic GLP-1 production. Microbiome augmentation and metabolite/protein production confers therapeutic effect when absorbed.

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Fleur Design[21]

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Pathway of GLP-1 Production[19]

Computational Optimization

To enhance GLP-1 stability and receptor binding, we employed computational design strategies:

  • Multiple Sequence Alignment (MSA): Evolutionary analysis to identify positions amenable to modification without disrupting structure or function
  • Shannon entropy analysis: Quantifies conservation to prioritize tolerant positions for potential modification
  • Structure-function optimization: Focusing on key residues (Leu, Ser, Gly, Ala) to enhance receptor binding while maintaining structural integrity
Entropy Analysis

Advantages of the Fleur System

Clinical Benefits

  • Oral delivery improves patient comfort and treatment adherence
  • Localized production may reduce systemic side effects
  • Synergistic interaction with the gut microbiome
  • Combines metabolic regulation with inherent possible probiotic benefits
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GLP-1 Clinical Benefits[16]

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GLP-1 Effects[13]

Economic Impact

  • Lower projected cost per unit with scalable biomanufacturing capabilities
  • Addresses both large and growing weight-loss and probiotic markets
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Obesity Treatment Cost[1]

Scientific Validation

Prior studies demonstrate successful GLP-1 expression from engineered bacteria in multiple animal models, including rats, mice, and non-human primates, supporting both efficacy and safety[1-6]. Humanely conducted animal trials have shown:

  • Significant reduction in fasting blood glucose levels
  • Increased insulin production in diabetic models
  • Improved glucose tolerance
  • Stable genetic expression over 30 days of continuous cultivation
  • Maintained probiotic properties including acid resistance and bile salt tolerance
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GLP-1 Animal Trials[18]

Innovation and Impact

Fleur integrates synthetic biology, probiotic health, computational design, and consumer-friendly formulation into a unified platform — representing a first step toward accessible, orally delivered peptide therapeutics.

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Next-Generation Probiotics for Inflammatory Bowel Disease[28]

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Oral delivery of therapeutic proteins by engineered bacterial type zero secretion system[29]

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Engineering Probiotics as Living Medicine[30]

Looking Forward

Given the escalating global burden of obesity and metabolic disease, Fleur could expand access to effective care, particularly for underserved communities who face high costs and limited availability of injectable therapies.

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Global Burden of Obesity[1]

Beyond GLP-1, our engineered probiotic platform may enable delivery of other therapeutic proteins within the gut microbiome — opening a path toward safe, personalized, and cost-effective treatments for a range of diseases.

Fleur concept illustration

References

  1. World Health Organization. (2024). Obesity and overweight. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
  2. International Diabetes Federation. (2025). IDF Diabetes Atlas (11th ed.). https://diabetesatlas.org/
  3. Centers for Disease Control and Prevention. (2024). Type 2 diabetes. https://www.cdc.gov/diabetes/about/about-type-2-diabetes.html
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  5. DeFronzo, R. A., Ferrannini, E., Groop, L., Henry, R. R., Herman, W. H., Holst, J. J., Hu, F. B., Kahn, C. R., Raz, I., Shulman, G. I., Simonson, D. C., Testa, M. A., & Weiss, R. (2015). Type 2 diabetes mellitus. Nature Reviews Disease Primers, 1(1), 15019. https://doi.org/10.1038/nrdp.2015.19
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  8. Hotamisligil, G. S. (2017). Inflammation, metaflammation and immunometabolic disorders. Nature, 542(7640), 177-185. https://doi.org/10.1038/nature21363
  9. Samuel, V. T., & Shulman, G. I. (2016). The pathogenesis of insulin resistance: Integrating signaling pathways and substrate flux. The Journal of Clinical Investigation, 126(1), 12-22. https://doi.org/10.1172/JCI77812
  10. Ozcan, U., Cao, Q., Yilmaz, E., Lee, A. H., Iwakoshi, N. N., Ozdelen, E., Tuncman, G., Görgün, C., Glimcher, L. H., & Hotamisligil, G. S. (2004). Endoplasmic reticulum stress links obesity, insulin action, and type 2 diabetes. Science, 306(5695), 457-461. https://doi.org/10.1126/science.1103160
  11. Weir, G. C., & Bonner-Weir, S. (2004). Five stages of evolving beta-cell dysfunction during progression to diabetes. Diabetes, 53(suppl_3), S16-S21. https://doi.org/10.2337/diabetes.53.suppl_3.S16
  12. Drucker, D. J. (2006). The biology of incretin hormones. Cell Metabolism, 3(3), 153-165. https://doi.org/10.1016/j.cmet.2006.01.004
  13. Holst, J. J. (2007). The physiology of glucagon-like peptide 1. Physiological Reviews, 87(4), 1409-1439. https://doi.org/10.1152/physrev.00034.2006
  14. Deacon, C. F. (2004). Therapeutic strategies based on glucagon-like peptide 1. Diabetes, 53(9), 2181-2189. https://doi.org/10.2337/diabetes.53.9.2181
  15. Mentlein, R. (2009). Mechanisms underlying the rapid degradation and elimination of the incretin hormones GLP-1 and GIP. Best Practice & Research Clinical Endocrinology & Metabolism, 23(4), 443-452. https://doi.org/10.1016/j.beem.2009.03.005
  16. Nauck, M. A., Quast, D. R., Wefers, J., & Meier, J. J. (2021). GLP-1 receptor agonists in the treatment of type 2 diabetes–state-of-the-art. Molecular Metabolism, 46, 101102. https://doi.org/10.1016/j.molmet.2020.101102
  17. Duan F, Curtis KL, March JC. Secretion of insulinotropic proteins by commensal bacteria: rewiring the gut to treat diabetes. Appl Environ Microbiol. 2008 Dec;74(23):7437-8. doi: 10.1128/AEM.01019-08. Epub 2008 Oct 3. PMID: 18836005; PMCID: PMC2592943.
  18. Hu, H., Luo, J., Liu, Y., Li, H., Jin, R., Li, S., Wei, J., Wei, H., & Chen, T. (2023). Improvement effect of a next-generation probiotic L. plantarum-pMG36e-GLP-1 on type 2 diabetes mellitus via the gut-pancreas-liver axis. Food & Function, 14, 3179–3195. https://doi.org/10.1039/d3fo00044c
  19. Wang, L., Chen, T., Wang, H., Wu, X., Cao, Q., Wen, K., Deng, K.-Y., & Xin, H. (2021). Engineered bacteria of MG1363-pMG36e-GLP-1 attenuated obesity-induced by high fat diet in mice. Frontiers in Cellular and Infection Microbiology, 11, Article 595575. https://doi.org/10.3389/fcimb.2021.595575
  20. Luo, J., Zhang, H., Lu, J., Ma, C., & Chen, T. (2021). Antidiabetic effect of an engineered bacterium Lactobacillus plantarum-pMG36e-GLP-1 in monkey model. Synthetic and Systems Biotechnology, 6, 272–282. https://doi.org/10.1016/j.synbio.2021.09.009
  21. Duan, F. F., Liu, J. H., & March, J. C. (2015). Engineered commensal bacteria reprogram intestinal cells into glucose-responsive insulin-secreting cells for the treatment of diabetes. Diabetes, 64(5), 1794–1803. https://doi.org/10.2337/db14-0635
  22. Pechenov, S., Revell, J., Will, S., Naylor, J., Tyagi, P., Patel, C., Liang, L., Tseng, L., Huang, Y., Rosenbaum, A. I., Balic, K., Konkar, A., Grimsby, J., & Subramony, J. A. (2021). Development of an orally delivered GLP-1 receptor agonist through peptide engineering and drug delivery to treat chronic disease. Scientific Reports, 11, Article 22521. https://doi.org/10.1038/s41598-021-01750-0
  23. Lu, X., Xie, Q., Pan, X. et al. (2024). Type 2 diabetes mellitus in adults: pathogenesis, prevention and therapy. Signal Transduction and Targeted Therapy, 9, 262. https://doi.org/10.1038/s41392-024-01951-9
  24. Frías, J. P., Auerbach, P., Bajaj, H. S., et al. (2021). Efficacy and safety of once‑weekly semaglutide 2.0 mg versus 1.0 mg in patients with type 2 diabetes (SUSTAIN FORTE): a double‑blind, randomised, phase 3B trial. Lancet Diabetes Endocrinol. 9(9):563‑574. https://doi.org/10.1016/S2213-8587(21)00211-4
  25. Mayendraraj, A., Rosenkilde, M. M., Gasbjerg, L. S. (2022). GLP‑1 and GIP receptor signaling in beta cells – A review of receptor interactions and co‑stimulation. Peptides 151:170749. https://doi.org/10.1016/j.peptides.2022.170749
  26. PDB101: GLP‑1 Receptor. RCSB PDB Educational Resources. https://pdb101.rcsb.org/global-health/diabetes-mellitus/drugs/incretins/target/glp-1-receptor
  27. Pesce, M., Seguella, L., Del Re, A., Lu, J., Palenca, I., Corpetti, C., Rurgo, S., Sanseverino, W., Sarnelli, G., & Esposito, G. (2022). Next‑Generation Probiotics for Inflammatory Bowel Disease. International Journal of Molecular Sciences, 23(10), 5466. https://doi.org/10.3390/ijms23105466
  28. Gong, X., Liu, S., Xia, B. et al. (2025). Oral delivery of therapeutic proteins by engineered bacterial type zero secretion system. Nature Communications 16, 1862. https://doi.org/10.1038/s41467-025-57153-6
  29. PLOS Blogs. (2017, Jan 11). Engineering Probiotics as Living Medicine. https://theplosblog.plos.org/2017/01/engineering-probiotics-as-living-medicine/