The Role of Serum Erythropoietin (EPO) and Vascular Endothelial Growth Factor (VEGF) in Pulse Wave Velocity (PWV) Among Hypertensive Patients: A Cross-Sectional Study

Abstract

Background and objective While hypertension (HTN) is a major health-related threat globally, it is often an under-reported clinical condition as most of the stage I hypertensive patients do not present with any symptoms. The relationship between endogenous oxygen-sensing protein [erythropoietin (EPO) and vascular endothelial growth factor (VEGF)] levels and vascular stress in hypertensive patients is not fully understood as the mechanistic pathway by which these oxygen-sensing proteins alter the vascular physiology and cause hypertension is still a matter of debate. In light of this, we explored the role of these two proteins in the development of vascular stress including increased pulse wave velocity (PWV). We aimed to examine the correlation between oxygen-sensing proteins and vascular stress markers including PWV in hypertensive patients. Materials and methods We conducted a cross-sectional study involving age-matched participants classified into three groups (group 1: normotensive persons, n=36; group 2: stage I hypertensive patients, n=36; and group 3, stage II hypertensive patients, n=36). Adiposity-related parameters such as waist circumference (WC), hip circumference (HC), BMI, and waist-hip ratio (WHR) were measured. BP was recorded manually in resting posture by using a sphygmomanometer. PWV, which predicts the progression of BP and the development of HTN, was recorded using a periscope, which works based on the oscillometric method. Vascular stress-induced oxidative stress parameters [serum malondialdehyde (MDA) and serum nitric oxide (NO)] were also estimated by using a UV spectrophotometer. Quantitative estimations of oxygen-sensing proteins (serum EPO and serum VEGF) were done by using the ELISA kit method. The results were expressed as mean ± standard deviation (SD). The correlation between the variables was done using Spearman’s correlation. A p-value <0.05 was considered statistically significant. Results Adiposity indices and vascular stiffness parameters were found to be significantly (p <0.05) increased in group 2 and group 3 compared to group 1. The levels of serum MDA were found to be significantly (p<0.05) increased in group 2 and group 3 than group 1, whereas the levels of serum NO were significantly (p<0.05) decreased in group 3 and group 2 than group 1. A significant (p<0.05) positive correlation was observed between the PWV and EPO (r=0.492) while a significant (p<0.05) negative correlation was observed between PWV and VEGF (r=-0.406) among the study population. Conclusion The results are indicative of the influence of vascular stress in stage I and II hypertensive patients. Furthermore, the relationship between oxygen-sensing proteins and vascular stress in hypertensive patients has also been established.