Assessment of ACE1 variants and ACE1/ACE2 expression in COVID-19 patients

Abstract

Contribution of the renin-angiotensinogen system in the risk of COVID-19 and related complications have been assessed by several groups. However, the results are not consistent. We examined levels of ACE1 and ACE2 in the circulation of two groups of COVID-19 patients (ICU-admitted and general ward-admitted patients) compared with healthy controls. We also genotyped two polymorphisms in ACE1 gene (the ACE1-I/D polymorphism rs1799752 and rs4359) to appraise their association with expression levels of ACE1 and ACE2. Expression level of ACE1 was significantly higher in ICU patients compared with non-ICU patients (P value = 0.02). However, its expression was not significantly different between total COVID-19 patients and total controls (P value = 0.34). ACE2 expression was not different ether between two groups of COVID-19 patients (P value = 0.12) or between total COVID-19 patients and total controls (P value = 0.79). While distribution of rs1799752 and rs4359 alleles was similar between study groups, genotype frequencies of rs1799752 were differently distributed among total COVID-19 patients and controls (P value = 0.00001). Moreover, genotypes of the other polymorphism tended to be distinctively distributed among these two groups (P value = 0.06). In the total population of patients and controls, different ACE1 mRNA levels were observed among carriers of different rs1799752 genotypes; of note, ID genotype carriers showed a higher expression of ACE1 compared with II genotype carriers (P = 0.01). ACE1 polymorphisms might affect risk of COVID-19 and expression of ACE transcripts.

Keywords: ACE1; ACE2; COVID-19; Expression.

Graphical abstract

Fig. 1

Distributions of alleles (a, c) and genotypes (b, d) of rs4359 and rs1799752 among normal controls (NC), COVID-19 patients, non-ICU and ICU-admitted cases. There was significant difference between genotypes distribution of rs1799752 among COVID-19 patients compared to matched controls.

Fig. 2

Relative expressions of ACE1 and ACE2 in COVID-19 patients (n = 91) compared with healthy controls (n = 91). There was no significant difference in expression of ACE1 or ACE2 between COVID-19 patients and healthy controls. However, a moderate increase in ACE1 expression was observed in ICU-admitted COVID-19 patients compared to other group of COVID-19 patients. – delta Ct values in the figures were plotted as box and whisker plots (showing the median [line], interquartile range [box], and minimum and maximum values).

Fig. 3

Association between ACE1 rs1799752 polymorphism and COVID-19 infection as well as ACE1 mRNA levels by rs1799752 genotypes. (a) The results of association tests under five different inheritance models are shown. The Odds Ratios (plus Confidence Intervals) are reported on the X axis in a linear scale. Data on the right of Y axis indicates causative effects toward the risk and the data on the left indicates protective effects. The ACE1 rs1799752 polymorphism was associated with a high risk of COVID-19 in dominant and co-dominant models. In the dominant model, the presence of at least one mutated (−) allele was tested against the homozygous wildtype genotype (wt/wt). The ACE1 rs1799752 polymorphism showed a significant protective effect against COVID-19 risk in over-dominant model. (b) In the total population of patients and controls, different ACE1 mRNA levels were observed among carriers of different rs1799752 genotypes; of note, ID genotype carriers showed a higher expression of ACE1 compared with II genotype carriers (P = 0.01). The level of Odds Ratios was showed as FDR adjusted q-values. MAF: minor allele frequency.

Fig. 4

ACE2 expression was significantly higher in ID genotype carriers than the II genotype carriers in total population.

Fig. 5

Association between ACE1 rs4359 gene polymorphism and COVID-19 risk as well as ACE1 mRNA levels by rs4359 genotypes. (a) The results of association tests under five different inheritance models are shown. The Odds Ratios (plus Confidence Intervals) are reported on the X axis in a linear scale. Data on the right of Y axis indicates causative effects toward the risk and the data on the left indicates protective effects. The ACE1 rs4359 polymorphism was associated with a higher risk of COVID-19 in dominant and co-dominant models. The ACE1 rs4359 polymorphism showed a significant protective effect against the risk for COVID-19 in over-dominant model. (b) There was no significant difference in the ACE1 expression level between rs4359 genotypes in the total population of patients and controls. Odds Ratios are shown as FDR adjusted q-values. MAF: minor allele frequency.

Fig. 6

ACE2 expression in carriers of different rs4359 genotypes in total population.

Fig. 7

Correlation between ACE1 and ACE2 expression levels. There was a strong positive correlation between ACE1 and ACE2 expression in COVID-19 patients (a), healthy controls (b), and total population (c).

Fig. 8

Correlation of ACE2 expression levels with age, RBC, HB, HCT, NEUT and ESR of COVID-19 patients. – delta CTs of ACE2 and log 2 of age and blood cells parameters were used for correlation tests.