Serum concentration of renin-angiotensin system components in association with ACE I/D polymorphism among hypertensive subjects in response to ACE inhibitor therapy

Background: Renin-angiotensin system (RAS) is a complex network of enzymes and peptides with the essential role in blood pressure control. The relationships between RAS components, RAS-related genetic polymorphisms and therapy response in essential hypertension (EH) were widely explored but the results were inconclusive.

Aim: The aim of this study was to explore the functional role of ACE insertion/deletion (I/D) polymorphism on the systemic quantity of angiotensin-converting enzyme (ACE), its homolog - ACE2, chymase and angiotensin II in EH patients with respect to achieved therapeutic blood pressure control.

Results: Genotyping of ACE I/D polymorphism was performed among 140 patients with EH from Bulgaria. The serological analyses reveal the significant elevation of the serum quantity of all investigated enzymes in EH than normotensive controls. In addition, serum ACE2 (183.57 pg/ml; vs. 151.78 pg/ml; p = 0.02) and chymase (68.5 pg/ml; vs. 23.66 pg/ml; p = 0.034) were significantly higher in patients with uncontrolled EH than controlled EH in response to ACE-inhibitory therapy. Also, ACE I/D polymorphism showed a significant impact on the serum ACE and chymase levels. ACE quantity was the highest among carriers of DD-genotype, followed by ID and II-genotype. Contrary, chymase was in the highest quantity in II-genotype compared to ID-genotype (p = 0.025) and DD-genotype (p = 0.044).

Conclusions: Our results suggest that insufficient blood pressure control by ACE-inhibitory therapy could be associated with elevation of serum ACE2 and chymase levels. Also, it appears that ACE I/D polymorphism may influence the circulating quantity of chymase in addition to ACE.