Fig. 6: IL7 treatment stimulates ACE2 expression in human endothelial cells.

a Network plot showing the DEGs related to SASP based on the bulk RNA-seq analysis of monkey lung, heart, and aorta. The color of connecting lines indicates the log₂FC. Genes with P < 0.06 are shown. b Network plot showing the DEGs related to cytokine storm based on the bulk RNA-seq analysis of monkey lung, heart, and aorta. The color of connecting lines indicates the log₂FC. Genes with P < 0.06 are shown. c Violin plots showing the transcript levels of IL7 in monkey lung, heart, and aorta from bulk RNA-seq analysis. d Bar plots showing the proportions of IL7⁺ cells across different cell types in monkey lung, heart, and aorta. e Pie plots showing the total IL7⁺ cell proportions between young and old groups in monkey lung, heart, and aorta. f Bar plots showing the IL7⁺ cell proportions between young and old groups across different cell types in monkey lung, heart, and aorta. g RT-qPCR showing the upregulation of ACE2 expression after a 6-h treatment with IL7 (10 ng/mL), IL1β (10 ng/mL) and IL6 (25 ng/mL) in HAECs (passage 1). The data are shown as means ± SEM, n = 4 experimental repeats, and the experiment was independently repeated three times with similar results. **P < 0.01, ***P < 0.001. h RT-qPCR showing the upregulation of ACE2 expression after treatment with IL7 (10 ng/mL) at different time points in HAECs (passage 2). The data are shown as means ± SEM, n = 4 experimental repeats, and the experiment was independently repeated three times with similar results. ***P < 0.001. i RT-qPCR detection of ACE2 expression in HAECs (passage 4) after treatment with IL7 in the presence or absence of vitamin C. Quantitative data are shown as means ± SEM. n = 4. ***P < 0.001. j Western blot analysis of ACE2 expression in HAECs after treatment with IL7 (10 ng/mL) and vitamin C (280 μM). GAPDH was used as a loading control. Quantitative data are shown as means ± SEM. n = 3 experimental repeats. *P < 0.05; **P < 0.01. k Schematic illustration of the functional decay and increased susceptibility to SARS-CoV-2 with age revealed by a transcriptomic atlas of aged primate cardiopulmonary system. SASP secretion increases (such as IL7) with age, thus promoting an inflammatory environment and inducing ACE2 expression, which may result in increased susceptibility to SARS-CoV-2.