Long-term intake of phenolic compounds attenuates age-related cardiac remodeling

Abstract

With the onset of advanced age, cardiac-associated pathologies have increased in prevalence. The hallmarks of cardiac aging include cardiomyocyte senescence, fibroblast proliferation, inflammation, and hypertrophy. The imbalance between levels of reactive oxygen species (ROS) and antioxidant enzymes is greatly enhanced in aging cells, promoting cardiac remodeling. In this work, we studied the long-term impact of phenolic compounds (PC) on age-associated cardiac remodeling. Three-month-old Wistar rats were treated for 14 months till middle-age with either 2.5, 5, 10, or 20 mg kg^-1 day^-1 of PC. PC treatment showed a dose-dependent preservation of cardiac ejection fraction and fractional shortening as well as decreased hypertrophy reflected by left ventricular chamber diameter and posterior wall thickness as compared to untreated middle-aged control animals. Analyses of proteins from cardiac tissue showed that PC attenuated several hypertrophic pathways including calcineurin/nuclear factor of activated T cells (NFATc3), calcium/calmodulin-dependent kinase II (CAMKII), extracellular regulated kinase 1/2 (ERK1/2), and glycogen synthase kinase 3ß (GSK 3ß). PC-treated groups exhibited reduced plasma inflammatory and fibrotic markers and revealed as well ameliorated extracellular matrix remodeling and interstitial inflammation by a downregulated p38 pathway. Myocardia from PC-treated middle-aged rats presented less fibrosis with suppression of profibrotic transforming growth factor-ß1 (TGF-ß1) Smad pathway. Additionally, reduction of apoptosis and oxidative damage in the PC-treated groups was reflected by elevated antioxidant enzymes and reduced RNA/DNA damage markers. Our findings pinpoint that a daily consumption of phenolic compounds could preserve the heart from the detrimental effects of aging storm.

Keywords: aging; cardiac remodeling; fibrosis; hypertrophy; oxidative stress; phenolic compounds.

Figure 1

Dose‐dependent recovery by phenolic compounds of age‐related hypertrophy observed by echocardiography. Left ventricular chamber and cardiac performance were over 14 months with or without PC or DMSO. Results are expressed as mean ± SEM. (a) LVIDd, (b) LVPWd, (c) IVSTd, (d) EF, and (e) FS. For SHAM‐DMSO rats: n = 6/group, and treated rats with PC: n = 8/group. #p < 0.05, time effect within each group (Month 14 vs. Month 1). *p < 0.05, effect of treatment after 14 months vs. SHAM and DMSO). PC 2.5 = phenolic compounds at 2.5 mg kg⁻¹ day⁻¹; PC 5 = phenolic compounds at 5 mg kg⁻¹ day⁻¹; PC 10 = phenolic compounds at 10 mg kg⁻¹ day⁻¹; PC 20 = phenolic compounds at 20 mg kg⁻¹ day⁻¹

Figure 2

Modulation of age‐induced cardiac remodeling by phenolic compound consumption. Representative western blot (left) and histograms analyses (right) for NFAT (a), calcineurin (b), ERK1/2 (c), CAMKII (d), and GSK 3ß (e) in rat cardiac tissue, normalized to GAPDH (in arbitrary units, a.u.). Values represent mean ± SEM (n = 3 for each protein and condition). *p < 0.05 and **p < 0.01 vs. young, #p < 0.05 and ##p < 0.01 vs. SHAM and DMSO. PC x = phenolic compounds at x mg kg⁻¹ day⁻¹

Figure 3

Dose‐dependent reduction of age‐related cardiac inflammation by phenolic compounds. (a) Representative microphotographs of left ventricular sections of the heart stained with hematoxylin‐eosin showing young, SHAM, DMSO, PC 2.5, PC 5, PC 10, and PC 20 groups. (b) Histograms showing cardiomyocytes width (μm) and semiquantitative scores of inflammation (n = 6–8 per group). (c) CRP and IL‐6 plasma concentrations in all groups (n = 6–8 per group). (d) Representative western blot analyses for p38 in rat cardiac tissue, normalized to GAPDH (in arbitrary units, a.u.) (n = 3 for each protein and condition). *p < 0.05 vs. young, #p < 0.05 and ##p < 0.01 vs. SHAM and DMSO. Results are mean ± SEM. PC x = phenolic compounds at x mg kg⁻¹ day⁻¹

Figure 4

Dose‐dependent regression of fibrosis related to advanced age by phenolic compound consumption. Quantification of interstitial fibrosis by Masson's trichrome staining of the left ventricle from SHAM, DMSO, and PC‐treated rats. (a) Collagen accumulation is shown in blue color. The control rat hearts (SHAM and DMSO) show increased interstitial fibrosis compared to the PC rat hearts. (b) Histogram showing percentage of fibrotic area (n = 6–8 per group). (c) TGF‐ß plasma concentrations in all groups (n = 6–8 per group). (d) Representative western blot (left) and histograms analyses (right) for Smad2 and Smad3 (n = 3 for each protein and condition) in rat cardiac tissue, normalized to GAPDH (in arbitrary units, a.u.). *p < 0.05 vs. young and #p < 0.05 vs. SHAM and DMSO. Results are mean ± SEM. PC x = phenolic compounds at x mg kg⁻¹ day⁻¹

Figure 5

Dose‐dependent inhibition of apoptosis and DNA/RNA oxidative damage in PC‐treated rat cardiac tissues. Representative images of TUNEL (a) and 8‐OHdG immunohistochemistry (b) in hearts obtained from young, SHAM, DMSO, PC 2.5, PC 5, PC 10, and PC 20 groups. Dark brown stains in (a) represent apoptotic nuclei. (c) Quantification of percentage of TUNEL‐positive areas. (d) % of 8‐OHDG‐positive cells. n = 6–8 per group. Values are mean ± SEM. *p < 0.05 and #p < 0.05 represent the comparison between all groups. PC x = phenolic compounds at x mg/kg/day

Figure 6

Dose‐dependent restoration by phenolic compounds of reduced activity of (SOD) 1 and 2 in SHAM, DMSO, and PC2.5. Western blot detection of SOD1 and SOD2 from cardiac tissue of control and PC‐treated rats, normalized to GAPDH (in arbitrary units, a.u.) (n = 3 for each protein and condition). *p < 0.05 vs. young and #p < 0.05 vs. SHAM and DMSO