A research team from the Medical University of Vienna has investigated structural changes in kidneys of patients with hypertension and type 2 diabetes. The results show that high blood pressure can lead to abnormalities in the podocytes, specialised cells in the renal filter, even without other pre-existing conditions such as diabetes. The results, published in the journal "Hypertension", underline the importance of early detection and consistent treatment of high blood pressure in order to prevent kidney damage.

To arrive at these results, the research team, led by Christopher Paschen and Rainer Oberbauer (Clinical Division of Nephrology and Dialysis, Department of Medicine III) and Heinz Regele (Clinical Department of Pathology), analysed kidney tissue from a total of 99 patients: who either suffered from high blood pressure (arterial hypertension) and type 2 diabetes or did not have either of the two conditions. The investigation was conducted on unaffected renal tissue samples from tumour nephrectomies (performed between 2013 and 2018), a surgical procedure in which a kidney is removed in whole or in part to treat a kidney tumour.

Using modern imaging and computer-assisted methods, the size and density of the podocytes and the volume of the renal corpuscles (glomeruli) were determined in the tissue samples. Podocytes are specialised cells of the renal corpuscles (glomeruli) that play a crucial role in the filtering function of the kidney. Their size and density are important indicators of the health of the kidney tissue. Artificial intelligence in the form of deep-learning-based image analysis was used for the analysis. With the help of a specially trained algorithm, digital tissue sections were automatically analysed to precisely capture the structure of podocytes and glomeruli.

Impaired kidney filtration
"The results show that patients with hypertension have a reduced density of podocytes compared to healthy controls and that their cell nuclei are enlarged compared to those of healthy controls," reports first author Christopher Paschen. These changes occurred independently of the additional diagnosis of type 2 diabetes and likely represent the first microscopically visible step towards impaired renal function. The study authors see this as an indication that high blood pressure can cause structural damage to the kidneys at an early stage and before clinical symptoms appear. "Early detection and treatment could help to slow the progression of kidney disease and prevent long-term damage," say the study leaders Rainer Oberbauer and Heinz Regele.

High blood pressure and type 2 diabetes are among the most common causes of chronic kidney disease. While the effects of diabetes on kidney function have been well researched, it was previously unclear to what extent high blood pressure causes direct structural changes even without additional diabetes. The current study provides new insights into this, which could be important for early detection and therapy planning.