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. 2021 Nov 11;164:13–16. doi: 10.1016/j.yjmcc.2021.11.003

Fig. 2.

Fig. 2

Sex- and age-differences in ACE2 levels in mouse and human hearts.

A. Representative immunoblot of mouse hearts for ACE2 protein levels (n = 6 biological replicates/group). Three gels were compiled for quantification (Supplementary Fig. S4). Data are represented as the mean ± SEM and were analyzed by two-way ANOVA with Tukey post hoc test; *p < 0.05; **p < 0.01, ***p < 0.001. For all experiments, young animals (n = 12) were obtained from four litters and each litter was collected over two days. Adult and aged animals (n = 12 /group) were obtained from five and three litters respectively, and each litter was collected over two days. B. Immunofluorescence of ACE2 (green) and pericyte marker NG2 (red). Wheat Germ Agglutinin (WGA) (blue) was used to delineate the cell membrane. Qualitative images were captured from n = 2 biological replicates and n = 16 (8 images/animal) technical replicates for each age group. C. Representative immunoblot for ACE2 in human hearts (n = 6, biological replicates/group). Two gels were compiled for quantification (Supplementary Fig. S4). Quantification represents the combined result from two western blots. Data are represented as the mean ± SEM and were analyzed by two-way ANOVA with Tukey post hoc test. * indicates differences from young males, and # indicates differences between aged males and aged females; *p < 0.05; **p < 0.01, ***p < 0.001 where the number of symbols indicates the level of significance. D. Immunofluorescence of ACE2 (green) and NG2 (red). WGA (blue) was used to delineate the cell membrane. Qualitative images were captured from n = 2 biological replicates and n = 16 (8 images/donor) technical replicates for each age group. E. ACE2 protein levels and activity are positively correlated, but not mRNA expression. * indicates differences from young males, and # indicates differences between aged males and aged females. *p < 0.05; **p < 0.01, ***p < 0.001 where the number of symbols indicates the level of significance. F. Schematic figure showing the multi-organ impact of sex and aging on ACE2 levels as a potential contributor to the increased male susceptibility to severe COVID-19. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)