Urinary extracellular vesicles reveal treatment responses in diabetic kidney disease

Diabetic kidney disease is one of the most common complications of diabetes and a leading cause of kidney failure. One of the earliest signs of kidney damage is albuminuria, the presence of excess albumin protein in the urine. While doctors can measure albuminuria to monitor disease progression, researchers are searching for additional biomarkers that provide a more detailed picture of what is happening inside the kidneys and how patients respond to treatment.

Researchers from the Erasmus MC University Medical Center Rotterdam, the Netherlands, investigated whether urinary extracellular vesicles (uEVs) could provide these insights. Extracellular vesicles are tiny membrane-bound particles released by cells that carry proteins, RNA, and other molecules reflecting the condition of their cells of origin. Because they are naturally released into urine, uEVs offer a noninvasive way to study kidney health.

The researchers analyzed urine samples from 20 people with diabetes and albuminuria who participated in a crossover clinical trial. Each participant received four commonly used kidney-protective therapies, telmisartan, empagliflozin, linagliptin, and baricitinib, with each treatment administered during separate four-week periods.

Using liquid chromatography tandem mass spectrometry, the team identified 2,441 proteins contained within urinary extracellular vesicles. Of these, 355 proteins were significantly associated with albuminuria, indicating that extracellular vesicles carry a rich molecular signature of kidney injury.

Each treatment produced its own unique pattern of protein changes. Empagliflozin produced the largest number of altered extracellular vesicle proteins, while the other three drugs also generated distinct proteomic signatures. Interestingly, there was very little overlap between the proteins affected by each medication, suggesting that these therapies influence different biological pathways despite all helping protect kidney function.

The researchers also compared their extracellular vesicle proteomics results with previously published single-cell and single-nucleus transcriptomic datasets from kidney tissue. Many of the protein changes observed in urinary extracellular vesicles matched corresponding changes in gene expression within kidney cells. Proteins that responded to sodium-glucose cotransporter 2 inhibitors showed especially strong agreement with the transcriptomic data.

Several groups of proteins were consistently associated with albuminuria, including proteins from podocytes, the specialized kidney cells responsible for filtering blood, as well as complement proteins involved in immune responses, lysosomal proteins, transport proteins, and extracellular vesicle markers such as Rab GTPases and tetraspanins.

These findings suggest that urinary extracellular vesicles capture detailed molecular information about kidney injury while also reflecting how different therapies alter disease biology. Because urine collection is simple and noninvasive, extracellular vesicle proteomics could eventually help physicians monitor disease progression, evaluate treatment effectiveness, and identify the therapies most likely to benefit individual patients.

Although larger clinical studies are still needed, this research highlights the growing potential of urinary extracellular vesicles as a valuable source of biomarkers for diabetic kidney disease and precision medicine.