Angiotensin-converting enzyme 2 in human plasma and lung tissue

• Published in: Blood pressure Vol. 32; no. 1; pp. 6 - 15
• Main Authors: Xie, Jing, Huang, Qi-Fang, Zhang, Zhihan, Dong, Yihan, Xu, Haimin, Cao, Yanan, Sheng, Chang-Sheng, Li, Yan, Wang, Chaofu, Wang, Xuefeng, Wang, Ji-Guang
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 31.12.2023
• Subjects: ACE2; Angiotensin I; Angiotensin-Converting Enzyme 2 - metabolism; Angiotensin-Converting Enzyme 2 - pharmacology; Antihypertensive Agents - pharmacology; China; COVID-19; Female; Humans; Hypertension; Lung; Male; Peptidyl-Dipeptidase A - metabolism; Peptidyl-Dipeptidase A - pharmacology; plasma; Renin-Angiotensin System; SARS-CoV-2 - metabolism; tissue; China; lung; ACE2; tissue; plasma; hypertension
• ISSN: 0803-7051; 1651-1999; 1651-1999
• DOI: 10.1080/08037051.2022.2154745

We investigated plasma angiotensin-converting enzyme 2 (ACE2) concentration in a population sample and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue in patients who underwent lung surgery. The study participants were recruited from a residential area in the suburb of Shanghai for the plasma ACE2 concentration study (n = 503) and the lung tissue samples were randomly selected from the storage in Ruijin Hospital (80 men and 78 age-matched women). In analyses adjusted for covariables, men had a significantly higher plasma ACE2 concentration (1.21 vs. 0.98 ng/mL, p = 0.027) and the mean intensity of ACE2 in the lung tissue (55.1 vs. 53.9 a.u., p = 0.037) than women. With age increasing, plasma ACE2 concentration decreased (p = 0.001), while the mean intensity of ACE2 in the lung tissue tended to increase (p = 0.087). Plasma ACE2 concentration was higher in hypertension than normotension, especially treated hypertension (1.23 vs. 0.98 ng/mL, p = 0.029 vs. normotension), with no significant difference between users of RAS inhibitors and other classes of antihypertensive drugs (p = 0.64). There was no significance of the mean intensity of ACE2 in the lung tissue between patients taking and those not taking RAS inhibitors (p = 0.14). Neither plasma ACE2 concentration nor the mean intensity of ACE2 in the lung tissue differed between normoglycemia and diabetes (p ≥ 0.20). ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics of patients. Plain language summary  What is the context?  * The primary physiological function of ACE2 is the degradation of angiotensin I and II to angiotensin 1-9 and 1-7, respectively.  * ACE2 was found to behave as a mediator of the severe acute respiratory syndrome coronavirus (SARS) infection.  * There is little research on ACE2 in humans, especially in the lung tissue.  * In the present report, we investigated plasma ACE2 concentration and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue respectively in two study populations.  What is new?  * Our study investigated both circulating and tissue ACE2 in human subjects. The main findings were:  * In men as well as women, plasma ACE2 concentration was higher in younger than older participants, whereas the mean intensity of ACE2 in the lung tissue increase with age increasing.  * Compared with normotension, hypertensive patients had higher plasma ACE2 concentration but similar mean intensity of ACE2 in the lung tissue.  * Neither plasma ACE2 concentration nor lung tissue ACE2 expression significantly differed between users of RAS inhibitors and other classes of antihypertensive drugs.  What is the impact?  * ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics, such as sex, age, and treated and untreated hypertension.  * A major implication is that plasma ACE2 concentration might not be an appropriate surrogate for the ACE2 expression in the lung tissue, and hence not a good predictor of SARS-COV-2 infection or fatality.