Age-Related Differential Structural and Transcriptomic Responses in the Hypertensive Heart

FIGURE 1. Blood pressure (BP) and left ventricular end-diastolic pressure (LVEDP) of young and aging sham and DOCA mice. (A) Systolic BP and (B) diastolic BP were higher in young and aging DOCA compared to sham mice. (C) Mean arterial pressure was only significantly higher in young DOCA compared to sham mice. (D) LVEDP was only significantly higher in aging DOCA compared to sham mice. Values are mean ± SEM. ∗q < 0.05, ∗∗q < 0.01, ∗∗∗q < 0.001 DOCA vs. sham control. Sample size: aging DOCA n = 8, all other groups n = 6.

FIGURE 2. Cardiac fibrosis of young and aging sham and DOCA mice. (A) Young and aging DOCA mice had higher perivascular and (B) interstitial fibrosis than sham mice. However, aging mice had more perivascular fibrosis than young mice. Values are mean ± SEM. ∗q < 0.05, ∗∗q < 0.01, ∗∗∗q < 0.001 DOCA vs. sham control. ###P < 0.001 young vs. aging DOCA. Scale bar: 50 μm. Sample size: aging DOCA n = 8, all other groups n = 6.

FIGURE 3. Cardiac transcriptome in young sham vs. DOCA mice. (A) Principal component analyses shows lack of sample group clustering on the first two dimensions for young sham vs. DOCA mice. (B) MA plot showing 899 differentially expressed genes (FDR < 0.05; Supplementary Table S3). Mechanisms differentially regulated between young sham and DOCA mice in the (C) GSEA analysis of Reactome Database and (D) Gsheat analysis of Molecular Signatures Database (MSigDB) (Supplementary Table S4). Sample size: n = 6 young sham vs. n = 4 young DOCA mice. CPM, counts per million; YD, young DOCA; YS, young sham.

FIGURE 4. Cardiac transcriptome in aging sham vs. DOCA mice. (A) Principal component analysis confirmed that aging sham and age-matched DOCA mice formed two distinctive groups. (B) MA plot showing 37 genes were differentially expressed between the two groups (FDR < 0.05; Supplementary Table S5). Mechanisms differentially regulated between aging sham and DOCA mice in the (C) GSEA analysis of Reactome Database and (D) Gsheat analysis of Molecular Signatures Database (MSigDB) (Supplementary Table S6). Sample size: n = 4 per group. CPM, counts per million; OD, aging DOCA; OS, aging sham.

FIGURE 5. Venn diagrams showing number of genes differentially expressed between (A) sham vs. DOCA mice according to age group (young vs. aging) and genes in common between the two groups; and (B) young and aging mice according to cardiovascular health (sham vs. DOCA). All genes in (A) and (B) are FDR < 0.05. (C) Rank–rank plot of all detected genes between young and aging DOCA mice showing they have similar patterns of gene expression.

FIGURE 6. Enrichment map highlighting major pathway up- (red) or down-regulated (blue) with aging. Showing reactome pathways (Supplementary Table S8) that had false discovery rate <0.05 in the gene-set enrichment analysis.

FIGURE 7. Two-dimensional pathway analysis showing differences between young and aging DOCA mice. Compared to young mice, aging DOCA mice had higher (A) collagen formation, (B) extracellular matrix organization, and (C) wound healing. (D) Both young and aging DOCA mice had activation of the respiratory electron transport chain. (E) Young DOCA mice had activation of oxidation and (F) potassium channels. On the other hand, aging DOCA had higher activation of TGF-beta (G) receptor and (H) targets, and (I) TNF-alpha genes. Sample size: n = 6 young DOCA vs. n = 4 aging DOCA mice.

FIGURE 8. Two-dimensional pathway analysis showing the activation of the immune system and inflammation in DOCA mice. (A) The immune system and (B) adaptive immune system were up-regulated in both ages. (C) The innate immune system, (D) cytokine, and (E) platelet signaling, among other inflammatory markers, were specifically up-regulated in aging DOCA mice only. Sample size: n = 6 young DOCA vs. n = 4 aging DOCA mice.

FIGURE 9. Two-dimensional pathway analysis of transcription factors, showing up-regulation of (A) Sin3A, (B) FOXM1, and (C) E2F4 targets. However, it caught our attention that very few were down-regulated in both ages with the DOCA phenotype. There were several transcription factors with increased expression in older hearts and lower expression in younger hearts, including (D) Nfkb, (E) Fosl2, (F) Zbtb7a, and (G) Stat3. (H) On the other hand there were few with increases in young hearts and decreases in older hearts, the best example being Srebp2. Sample size: n = 6 young DOCA vs. n = 4 aging DOCA mice.

FIGURE 10. Two-dimensional pathway analysis of microRNAs whose targets were down-regulated in both young and aging DOCA mice (full list at Supplementary Table S10). Showing some examples including (A) let-7B, (B) let-7c, (C) let-7e, and (D) miR-122.