Is hypertension in African-descent populations contributed to by an imbalance in the activities of the ACE2/Ang-(1-7)/Mas and the ACE/Ang II/AT₁ axes?

Abstract

Introduction: Low plasma renin activity hypertension is prevalent in Afro-Caribbean persons. Reduced angiotensin converting enzyme 2 activity from the counter angiotensin converting enzyme 2 /angiotensin-(1-7)/Mas receptor axis of the renin angiotensin aldosterone system has been reported in people with pre-hypertension, type 2 diabetes mellitus and chronic renal disease. This study investigates whether an imbalance in the regulatory mechanisms between the pressor arm of the renin angiotensin aldosterone system (angiotensin converting enzyme/angiotensin II/AT1 receptor) and the depressor axis (angiotensin converting enzyme 2/angiotensin-(1-7)/Mas receptor) predisposes persons of African descent to hypertension. Methods: In total, 30 normotensives and 30 recently diagnosed hypertensives aged 18–55 of Afro-Caribbean origin who are naïve to antihypertensive treatment will be recruited from public sector polyclinics in Barbados. Demographic and anthropometric data, clinical blood pressure readings, 24-hour urine collections and venous blood samples will be collected. Biological samples will be analysed for renin angiotensin aldosterone system peptide markers using radioimmunoassay. Conclusion: We describe the design, methods and rationale for the characterization of renin angiotensin aldosterone system mechanisms that may contribute to hypertension predisposition in persons of African descent. Our findings will characterize any imbalance in the counter axes of the renin angiotensin aldosterone system in hypertensive Afro-Caribbeans with a potential view of identifying novel approaches with the use of renin angiotensin aldosterone system and mineralocorticoid blockers to manage the condition.

Significant Unresolved Questions and Opportunities for Bioengineering in Understanding and Treating COVID-19 Disease Progression

“…Expression of ACE2 is at a lower level in the black population, which puts this group at higher risk of arterial hypertension and end organ damage. 47 However, the black population in the United States is being affected by the virus at higher rates. While there are confounding factors, such as socioeconomic status, it is thought decreased expression of ACE2 may limit initial infection rates by SARS-CoV-2.…”

Differences in RAAS/vitamin D linked to genetics and socioeconomic factors could explain the higher mortality rate in African Americans with COVID-19

“…However, some studies propose the idea that hypertension in Black people could develop from an imbalance between the RAAS (ACE/Ang II/AT1 receptor) pressor arm and the depressor axis [ACE2/Ang-(1-7)/Mas receptor], where ACE2 as protective RAAS axis would be reduced in hypertensive Black patients. 105 Moreover, another study reported that ACE2 expression was increased only in Asians but not in other ethnic populations. 106 Concerning genetic polymorphisms, African American people have an insertion/deletion polymorphism in the angiotensin I converting enzyme gene, which stimulates higher production of tissue angiotensin II and would predispose them to the development of hypertension and related diseases more frequently than White people.…”

Interplay of COVID-19 and cardiovascular diseases in Africa: an observational snapshot

“…It is worth noting that the regimen of ACE inhibitors commonly used in the African population are marred with contraindications which neither pharmacogenomics nor genetics seem to offer a solid explanation for [ 28 , 29 ]. In as much as ACE/ACE2 axes plays an important role in hypertensives of African descent, further research should be done to investigate potential involvement of other molecules in the RAAS complex [ 30 ]. Potential involvement of other hypertensive molecules that are not directly controlled by the ACE/ACE2 inflammatory pathways would potentially explain the disproportionate mortalities, despite high prevalence of hypertensives in African populations.…”