Angiotensin converting enzyme 2 level and its significance in COVID‐19 and other diseases patients

Background Angiotensin‐converting enzyme 2 (ACE2) expressions and its modulation are of great interest as being a key receptor for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2) and the protective arm of the rennin‐angiotensin axis, maintaining cardiovascular homeostasis. However, ACE2 expressions and their modulation in the healthy and disease background are yet to be explored. Method We performed a meta‐analysis, extracting the data for ACE2 expression in human subjects with various diseases, including SARS‐CoV2 infection without or with co‐morbidity. The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines were followed. Out of 203 studies, 39 met the inclusion criteria with SARS‐CoV2 patients without co‐morbidity, SARS‐CoV2 patients with co‐morbidity, cardiovascular (CVD) patients, diabetes patients, kidney disorders patients, pulmonary disease patients, and other viral infections patients. Results Angiotensin‐converting enzyme 2 expression was significantly increased in all diseases. There was an elevated level of ACE2, especially membrane‐bound ACE2, in COVID‐19 patients compared to healthy controls. A statistically significant increase in ACE2 expression was observed in CVD patients and patients with other viral diseases compared to healthy subjects. Moreover, subgroup analysis of ACE2 expression as soluble and membrane‐bound ACE2 revealed a remarkable increase in membrane‐bound ACE2 in CVD patients, patients with viral infection compared to soluble ACE2 and pooled standard mean difference (SMD) with the random‐effects model was 0.37 and 2.23 respectively. Conclusion It was observed that utilizing the ACE2 by SARS‐CoV2 for its entry and its consequence leads to several complications. So there is a need to investigate the underlying mechanism along with novel therapeutic strategies. Our review and meta‐analysis substantially add novel knowledge to our understanding of ACE2 expression pattern, its dynamic as soluble and membrane‐bound form. An elevated level of ACE2 in patients with all diseases was observed. Moreover, membrane‐bound ACE2 was remarkably high in patients with SARS‐CoV2 infected patients having co‐morbidities, cardiovascular diseases, and other viral diseases compared to healthy population.