Study on the Clinical Significance of ACE2 and Its Age-Related Expression

Abstract

Background ACE2 plays a particular role in the changes in multiple organ functions. However, whether ACE2 expression differs at different ages and whether it plays a role in infection-related organ dysfunction remains unclear. Methods Female and male C57BL/6 mice in four different age groups were included in this study. Immunohistochemical and Western blot analyses were performed to evaluate ACE2 expression characteristics in lung tissues. At the same time, we detected the changes of ACE2 in human blood of different ages and evaluated its clinical significance in sepsis-associated organ dysfunction (SAOD). Results This study indicated that ACE2 is expressed differently in mouse lung tissues at four different ages (P < 0.05). The peak expression distribution of ACE2 in lung tissues was in the newborn and middle-aged cohorts (P < 0.05). Infants younger than one year had a significantly higher concentration of ACE2 in serum and enhanced susceptibility compared with other ages (P < 0.05). Serum APTT, D-dimer, LDH, and PCT, as well as ACE2 in sepsis and SAOD groups, were statistically significant (P < 0.05) and were related to an increased risk of SAOD. There was a positive correlation between ACE2 and D-dimer (P < 0.05). Conclusion The levels of ACE2 expression varied in different age groups. It tends to be higher in infants and young children. This result suggests that young children are more susceptible to infection. Moreover, a cutoff value for the ACE2 level >1551.15 pg/mL and D-dimer >984.5 U/L should be considered a warning sign of infection-associated organ dysfunction and guide the clinician in evaluating the patient’s multiple organ function.

Beyond Acute COVID-19: Investigating the Incidence of Subacute Thyroiditis in Long COVID-19 in Korea

“…This finding could be explained by age-related changes in the immune system, resulting in a decreased immune response to infections in the elderly population. In contrast, a more robust immune response to infections is preserved in younger patients and it leads to increase the risk of SAT following COVID-19 [ 31 ]. Another plausible mechanism for the higher incidence of SAT in young age could be attributed to the higher expression of ACE2 [ 32 ].…”

COVID-19 in Older Individuals Requiring Hospitalization

“…On the other hand, SARS-CoV-2 infection may lead to a decrease in the ACE2 protein levels, which may increase the expression of pro-inflammatory mediators, leading to increased severity and higher mortality of COVID-19 [ 22 , 23 , 24 , 25 ]. This is of particular importance in older patients, as ACE2 levels decline with age, making them more vulnerable to the immunologic consequences associated with the ACE2 level reduction induced by SARS-CoV-2 [ 26 ]. Moreover, anatomical changes in the lungs and the potential for atrophy of the respiratory muscles can be associated with changes in respiratory function, making older individuals more vulnerable to complications of COVID-19 due to a reduction in the respiratory reserve and decreased defense barriers.…”

Advances in Modelling COVID-19 in Animals

“…ACE2 receptor expression has been described to both increase (Baker et al, 2021;Wark et al, 2021) and decrease (Chen et al, 2020;J. ;Gu et al, 2021;Xudong et al, 2006;Yoon et al, 2016) with age in humans and rodents. However, Berni Canani et al (2021) observed no significant differences in ACE2 expression between children <10 years old and adults 20-80 years old, detected this same trend when comparing expression across multiple tissues in adults above or below 49 years of age.…”