Right ventricular protein expression profile in end-stage heart failure

Serum a-1 antitrypsin as a novel biomarker in chronic heart failure

AIMS

Chronic heart failure (CHF) remains a major health issue worldwide. In the present study, we aimed to identify novel circulating biomarkers for CHF using serum proteomics technology and to validate the biomarker in three independent cohorts.

METHODS AND RESULTS

The isobaric tags for relative and absolute quantitation technology was utilized to identify the potential biomarkers of CHF. The validation was conducted in three independent cohort. Cohort A included 223 patients with ischaemic heart disease (IHD) and 321 patients with ischaemic heart failure (IHF) from the CORFCHD-PCI study. Cohort B recruited 817 patients with IHD and 1139 patients with IHF from the PRACTICE study. Cohort C enrolled 559 non-ischaemic heart disease patients with CHF (n = 316) or without CHF (n = 243). We found the expression of a-1 antitrypsin (AAT) was elevated significantly in patients with CHF compared with that in the patients with stable IHD using statistical and bioinformatics analyses. In a validation study, there was a significant difference between patients with stable IHD and patients with IHF in AAT concentration either in cohort A (1.35 ± 0.40 vs. 1.64 ± 0.56, P < 0.001) or in cohort B (1.37 ± 0.42 vs. 1.70 ± 0.48, P < 0.001). The area under the receiver operating characteristic curve was 0.70 [95% confidence interval (CI): 0.66 to 0.74, P < 0.001] in cohort A and 0.74 (95% CI: 0.72 to 0.76, P < 0.001) in cohort B. Furthermore, AAT was negative correlated with left ventricular ejection fraction (r = -0.261, P < 0.001). After adjusting for confounders using a multivariate logistic regression analysis, AAT remained an independent association with CHF in both cohort A (OR = 3.14, 95% CI: 1.667 to 5.90, P < 0.001) and cohort B (OR = 4.10, 95% CI: 2.97 to 5.65, P < 0.001). This association was also validated in cohort C (OR = 1.86, 95% CI: 1.02 to 3.38, P = 0.043).

CONCLUSIONS

The present study suggests that serum AAT is a reliable biomarker for CHF in a Chinese population.

Ythdf2 regulates cardiac remodeling through its mRNA target transcripts

m6A mRNA methylation controls cardiomyocyte function and increased overall m6A levels are a stereotyping finding in heart failure independent of the underlying etiology. However, it is largely unknown how the information is read by m6A reader proteins in heart failure. Here we show that the m6A reader protein Ythdf2 controls cardiac function and identified a novel mechanism how reader proteins control gene expression and cardiac function. Deletion of Ythdf2 in cardiomyocytes in vivo leads to mild cardiac hypertrophy, reduced heart function, and increased fibrosis during pressure overload as well as during aging. Similarly, in vitro the knockdown of Ythdf2 results in cardiomyocyte growth and remodeling. Mechanistically, we identified the eucaryotic elongation factor 2 as post-transcriptionally regulated by Ythdf2 using cell type specific Ribo-seq data. Our study expands our understanding on the regulatory functions of m6A methylation in cardiomyocytes and how cardiac function is controlled by the m6A reader protein Ythdf2.

Emerging role of T3-binding protein μ-crystallin (CRYM) in health and disease

Thyroid hormones are essential metabolic and developmental regulators that exert a huge variety of effects in different organs. Triiodothyronine (T3) and thyroxine (T4) are synthesized in the thyroid gland and constitute unique iodine-containing hormones that are constantly regulated by a homeostatic feedback mechanism. T3/T4 activity in cells is mainly determined by specific transporters, cytosolic binding proteins, deiodinases (DIOs), and nuclear receptors. Modulation of intracellular T3/T4 level contributes to the maintenance of this regulatory feedback. μ-Crystallin (CRYM) is an important intracellular high-affinity T3-binding protein that buffers the amount of T3 freely available in the cytosol, thereby controlling its action. In this review, we focus on the molecular and pathological properties of CRYM in thyroid hormone signaling, with emphasis on its critical role in malignancies.

Mettl3-mediated m6A modification of Fgf16 restricts cardiomyocyte proliferation during heart regeneration

Cardiovascular disease is the leading cause of death worldwide due to the inability of adult heart to regenerate after injury. N6-methyladenosine (m6A) methylation catalyzed by the enzyme methyltransferase-like 3 (Mettl3) plays an important role in various physiological and pathological bioprocesses. However, the role of m6A in heart regeneration remains largely unclear. To study m6A function in heart regeneration, we modulated Mettl3 expression in vitro and in vivo. Knockdown of Mettl3 significantly increased the proliferation of cardiomyocytes and accelerated heart regeneration following heart injury in neonatal and adult mice. However, Mettl3 overexpression decreased cardiomyocyte proliferation and suppressed heart regeneration in postnatal mice. Conjoint analysis of methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq identified Fgf16 as a downstream target of Mettl3-mediated m6A modification during postnatal heart regeneration. RIP-qPCR and luciferase reporter assays revealed that Mettl3 negatively regulates Fgf16 mRNA expression in an m6A-Ythdf2-dependent manner. The silencing of Fgf16 suppressed the proliferation of cardiomyocytes. However, the overexpression of ΔFgf16, in which the m6A consensus sequence was mutated, significantly increased cardiomyocyte proliferation and accelerated heart regeneration in postnatal mice compared with wild-type Fgf16. Our data demonstrate that Mettl3 post-transcriptionally reduces Fgf16 mRNA levels through an m6A-Ythdf2-dependen pathway, thereby controlling cardiomyocyte proliferation and heart regeneration.

Lower troponin expression in the right ventricle of rats explains interventricular differences in E-C coupling

Despite distinctive functional and anatomic differences, a precise understanding of the cardiac interventricular differences in excitation–contraction (E–C) coupling mechanisms is still lacking. Here, we directly compared rat right and left cardiomyocytes (RVCM and LVCM). Whole-cell patch clamp, the IonOptix system, and fura-2 fluorimetry were used to measure electrical properties (action potential and ionic currents), single-cell contractility, and cytosolic Ca²⁺ ([Ca²⁺]_i), respectively. Myofilament proteins were analyzed by immunoblotting. RVCM showed significantly shorter action potential duration (APD) and higher density of transient outward K⁺ current (I_to). However, the triggered [Ca²⁺]_i change (Ca²⁺ transient) was not different, while the decay rate of the Ca²⁺ transient was slower in RVCM. Although the relaxation speed was also slower, the sarcomere shortening amplitude (ΔSL) was smaller in RVCM. SERCA activity was ∼60% lower in RVCM, which is partly responsible for the slower decay of the Ca²⁺ transient. Immunoblot analysis revealed lower expression of the cardiac troponin complex (cTn) in RVCM, implying a smaller Ca²⁺ buffering capacity (κ_S), which was proved by in situ analysis. The introduction of these new levels of cTn, I_to, and SERCA into a mathematical model of rat LVCM reproduced the similar Ca²⁺ transient, slower Ca²⁺ decay, shorter APD, and smaller ΔSL of RVCM. Taken together, these data show reduced expression of cTn proteins in the RVCM, which provides an explanation for the interventricular difference in the E–C coupling kinetics.

Loss of m6A methyltransferase METTL3 promotes heart regeneration and repair after myocardial injury

AIMS

N6-Methyladenosine (m6A), one of the important epigenitic modifications, is very commom in messenger RNAs (mRNAs) of eukaryotes, and has been involved in various diseases. However, the role of m6A modification in heart regeneration after injury remains unclear. The study was conducted to investigate whether targeting methyltransferase-like 3 (METTL3) could replenish the loss of cardiomyocytes (CMs) and improve cardiac function after myocardial infarction (MI).

METHODS AND RESULTS

METTL3 knockout mouse line was generated. A series of functional experiments were carried out and the molecular mechanism was further explored. We identified that METTL3, a methyltransferase of m6A methylation, is upregulated in mouse hearts after birth, which is the opposite of the changes in CMs proliferation. Furthermore, both METTL3 heterozygous knockout mice and administration of METTL3 shRNA adenovirus in mice exhibited CMs cell cycle re-entered, infract size decreased and cardiac function improved after MI. Mechanically, the silencing of METTL3 promoted CMs proliferation by reducing primary miR-143 (pri-miR-143) m6A modificaiton, thereby inhibiting the pri-miR-143 into mature miR-143-3p. Moreover, we found that miR-143-3p has targeting effects on Yap and Ctnnd1 so as to regulate CMs proliferation.

CONCLUSION

METTL3 deficiency contributes to heart regeneration after MI via METTL3-pri-miR-143-(miR-143)-Yap/Ctnnd1 axis. This study provides new insights into the significance of RNA m6A modification in heart regeneration.

Nandrolone combined with strenuous resistance training impairs myocardial proteome profile of rats

We aimed to investigate the effects of high doses of nandrolone decanoate and resistance training (RT) on the proteomic profile of the left ventricle (LV) of rats, using a label-free quantitative approach. Male rats were randomized into four groups: untrained vehicle (UTV), trained vehicle (TV), untrained nandrolone (UTN), and trained nandrolone (TN). Rats were familiarized with the exercise training protocol (jump exercise) for one week. Jump-exercise was performed five days a week for 6 weeks, with 30 s of inter-set rest intervals. Nandrolone was administrated for 6 weeks (5 mg/kg, twice a week, via intramuscular). Systolic and diastolic arterial pressure and heart rate were measured 48 h post-training. LV was isolated and collagen content was measured. The expression of cardiac proteins was analyzed by ultra-efficiency liquid chromatography with mass spectrometry high / low collision energy (UPLC/MSE). Nandrolone and RT led to cardiac hypertrophy, even though high doses of nandrolone counteracted the RT-induced arterial pressures lowering. Nandrolone also affected the proteome profile negatively in LV of rats, including critical proteins related to biological processes (metabolism, oxidative stress, inflammation), structural function and membrane transporters. Our findings show physiological relevance since high doses of nandrolone induced detrimental effects on the proteome profile of heart tissue and hemodynamic parameters of rats. Furthermore, as nandrolone abuse has become increasingly common among recreational athletes and casual fitness enthusiasts, we consider that our findings have clinical relevance as well.

Interventricular Differences of Signaling Pathways-Mediated Regulation of Cardiomyocyte Function in Response to High Oxidative Stress in the Post-Ischemic Failing Rat Heart

Standard heart failure (HF) therapies have failed to improve cardiac function or survival in HF patients with right ventricular (RV) dysfunction suggesting a divergence in the molecular mechanisms of RV vs. left ventricular (LV) failure. Here we aimed to investigate interventricular differences in sarcomeric regulation and function in experimental myocardial infarction (MI)-induced HF with reduced LV ejection fraction (HFrEF). MI was induced by LAD ligation in Sprague-Dawley male rats. Sham-operated animals served as controls. Eight weeks after intervention, post-ischemic HFrEF and Sham animals were euthanized. Heart tissue samples were deep-frozen stored (n = 3-5 heart/group) for ELISA, kinase activity assays, passive stiffness and Ca²⁺-sensitivity measurements on isolated cardiomyocytes, phospho-specific Western blot, and PAGE of contractile proteins, as well as for collagen gene expressions. Markers of oxidative stress and inflammation showed interventricular differences in post-ischemic rats: TGF-β1, lipid peroxidation, and 3-nitrotyrosine levels were higher in the LV than RV, while hydrogen peroxide, VCAM-1, TNFα, and TGF-β1 were increased in both ventricles. In addition, nitric oxide (NO) level was significantly decreased, while FN-1 level was significantly increased only in the LV, but both were unchanged in RV. CaMKII activity showed an 81.6% increase in the LV, in contrast to a 38.6% decrease in the RV of HFrEF rats. Cardiomyocyte passive stiffness was higher in the HFrEF compared to the Sham group as evident from significantly steeper F_passive vs. sarcomere length relationships. In vitro treatment with CaMKIIδ, however, restored cardiomyocyte passive stiffness only in the HFrEF RV, but had no effect in the HFrEF LV. PKG activity was lower in both ventricles in the HFrEF compared to the Sham group. In vitro PKG administration decreased HFrEF cardiomyocyte passive stiffness; however, the effect was more pronounced in the HFrEF LV than HFrEF RV. In line with this, we observed distinct changes of titin site-specific phosphorylation in the RV vs. LV of post-ischemic rats, which may explain divergent cardiomyocyte stiffness modulation observed. Finally, Ca²⁺-sensitivity of RV cardiomyocytes was unchanged, while LV cardiomyocytes showed increased Ca²⁺-sensitivity in the HFrEF group. This could be explained by decreased Ser-282 phosphorylation of cMyBP-C by 44.5% in the RV, but without any alteration in the LV, while Ser-23/24 phosphorylation of cTnI was decreased in both ventricles in the HFrEF vs. the Sham group. Our data pointed to distinct signaling pathways-mediated phosphorylations of sarcomeric proteins for the RV and LV of the post-ischemic failing rat heart. These results implicate divergent responses for oxidative stress and open a new avenue in targeting the RV independently of the LV.

The role of TXNL1 in disease: treatment strategies for cancer and diseases with oxidative stress

Thioredoxin-like protein-1 (TXNL1; also known as thioredoxin-related 32 kDa protein, TRP32) is a thioredoxin involved in the regulation of oxidative stress, which protects cells from damage through redox balance. Studies have shown that TXNL1 has a variety of functions, including cell signal transduction, cell cycle regulation, protein synthesis, modification and degradation, vesicle transport, transcriptional regulation, cell apoptosis, virus replication and oxidative stress regulation, etc., and plays an important role in the occurrence and development of human diseases. Therefore, TXNL1 has a strong correlation with the treatment of cancer and oxidative stress diseases. In this paper, the basic structure, function and potential application value of TXNL1 in diseases are reviewed, so as to open up new targets for the treatment of cancer and oxidative stress-related diseases.

Analysis of DCM associated protein alterations of human right and left ventricles

Dilated cardiomyopathy (DCM) is characterized by ventricular chamber enlargement and impaired myocardial function. Endomyocardial biopsies (EMB) enable immunohistochemical and molecular characterization of this disease. However, knowledge about specific molecular patterns and their relation to cardiac function in both ventricles is rare. Therefore, we performed a mass spectrometric analysis of 28 paired EMBs of left (LV) and right ventricles (RV) of patients with DCM or suspected myocarditis allowing quantitative profiling of 743 proteins. We analysed associations between protein abundance of LV and RV as well as the echocardiographic parameters LVEF, TAPSE, LVEDDI, and RVEDDI by linear regression models. Overall, more LV than RV proteins were associated with LV parameters or with RVEDDI. Most LV and RV proteins increasing in level with impairing of LVEF were annotated to structural components of cardiac tissue. Additionally, a high proportion of LV proteins with metabolic functions decreased in level with decreasing LVEF. Results were validated with LV heart sections of a genetic murine heart failure model. The study shows, that remodelling and systolic dysfunction in DCM is mirrored by distinct alterations in protein composition of both ventricles. Loss of LV systolic function is reflected predominantly by alterations in proteins assigned to metabolic functions in the LV whereas structural remodelling was more obvious in the RV. Alterations related to intermediate filaments were seen in both ventricles and highlight such proteins as early indicators of LV loss of function. SIGNIFICANCE: The present study report protein sets in the RV and the LV being associated with ventricular function and remodelling in DCM. Protein abundances in the LV and the RV emphasize and expand current knowledge on pathophysiological changes in heart failure and DCM. While RV and LV EMBs do not differ concerning diagnostic assessment of inflammatory status and virus persistence, additional information reflecting disease severity associated protein alterations can be gained by EMB protein profiling. RV and LV protein data provided complementary information. The protein pattern of the LV reflects metabolic changes and an impaired energy production, which is associated with the degree of LV systolic dysfunction and remodelling and may yield important information about the disease status in DCM. On the other hand, at this disease stage of DCM with still preserved RV function, RV alterations in structural proteins may reflect myocardial compensatory protective mechanisms for maintenance of structure and cellular function. The study highlight particular proteins being of interest as heart failure biomarkers in both ventricles which seem to reflect the severity of the disease. Further comparative studies between different HF aetiologies have to evaluate those proteins as markers specific for DCM.

Role of m6A RNA methylation in cardiovascular disease (Review)

N⁶-methyladenosine (m⁶A) is the most prevalent and abundant type of internal post-transcriptional RNA modification in eukaryotic cells. Multiple types of RNA, including mRNAs, rRNAs, tRNAs, long non-coding RNAs and microRNAs, are involved in m⁶A methylation. The biological function of m⁶A modification is dynamically and reversibly mediated by methyltransferases (writers), demethylases (erasers) and m⁶A binding proteins (readers). The methyltransferase complex is responsible for the catalyzation of m⁶A modification and is typically made up of methyltransferase-like (METTL)3, METTL14 and Wilms tumor 1-associated protein. Erasers remove methylation by fat mass and obesity-associated protein and ALKB homolog 5. Readers play a role through the recognition of m⁶A-modified targeted RNA. The YT521-B homology domain family, heterogeneous nuclear ribonucleoprotein and insulin-like growth factor 2 mRNA-binding protein serve as m⁶A readers. The m⁶A methylation on transcripts plays a pivotal role in the regulation of downstream molecular events and biological functions, such as RNA splicing, transport, stability and translatability at the post-transcriptional level. The dysregulation of m⁶A modification is associated with cancer, drug resistance, virus replication and the pluripotency of embryonic stem cells. Recently, a number of studies have identified aberrant m⁶A methylation in cardiovascular diseases (CVDs), including cardiac hypertrophy, heart failure, arterial aneurysm, vascular calcification and pulmonary hypertension. The aim of the present review article was to summarize the recent research progress on the role of m⁶A modification in CVD and give a brief perspective on its prospective applications in CVD.

FTO-Dependent N6-Methyladenosine Regulates Cardiac Function During Remodeling and Repair

BACKGROUND

Despite its functional importance in various fundamental bioprocesses, studies of N⁶-methyladenosine (m6A) in the heart are lacking. Here, we show that the FTO (fat mass and obesity-associated protein), an m6A demethylase, plays a critical role in cardiac contractile function during homeostasis, remodeling, and regeneration.

METHODS

We used clinical human samples, preclinical pig and mouse models, and primary cardiomyocyte cell cultures to study the functional role of m6A and FTO in the heart and in cardiomyocytes. We modulated expression of FTO by using adeno-associated virus serotype 9 (in vivo), adenovirus (both in vivo and in vitro), and small interfering RNAs (in vitro) to study its function in regulating cardiomyocyte m6A, calcium dynamics and contractility, and cardiac function postischemia. We performed methylated (m6A) RNA immunoprecipitation sequencing to map transcriptome-wide m6A, and methylated (m6A) RNA immunoprecipitation quantitative polymerase chain reaction assays to map and validate m6A in individual transcripts, in healthy and failing hearts, and in myocytes.

RESULTS

We discovered that FTO has decreased expression in failing mammalian hearts and hypoxic cardiomyocytes, thereby increasing m6A in RNA and decreasing cardiomyocyte contractile function. Improving expression of FTO in failing mouse hearts attenuated the ischemia-induced increase in m6A and decrease in cardiac contractile function. This is performed by the demethylation activity of FTO, which selectively demethylates cardiac contractile transcripts, thus preventing their degradation and improving their protein expression under ischemia. In addition, we demonstrate that FTO overexpression in mouse models of myocardial infarction decreased fibrosis and enhanced angiogenesis.

CONCLUSIONS

Collectively, our study demonstrates the functional importance of the FTO-dependent cardiac m6A methylome in cardiac contraction during heart failure and provides a novel mechanistic insight into the therapeutic mechanisms of FTO.

Phosphodiesterase-5 Is Elevated in Failing Single Ventricle Myocardium and Affects Cardiomyocyte Remodeling In Vitro

Background Single ventricle (SV) congenital heart disease is fatal without intervention, and eventual heart failure is a major cause of morbidity and mortality. Although there are no proven medical therapies for the treatment or prevention of heart failure in the SV heart disease population, phosphodiesterase-5 inhibitors (PDE5i), such as sildenafil, are increasingly used. Although the pulmonary vasculature is the primary target of PDE5i therapy in patients with SV heart disease, the effects of PDE5i on the SV heart disease myocardium remain largely unknown. We sought to determine PDE5 expression and activity in the single right ventricle of SV heart disease patients relative to nonfailing controls and to determine whether PDE5 impacts cardiomyocyte remodeling using a novel serum-based in vitro model. Methods and Results PDE5 expression (n=9 nonfailing; n=7 SV heart disease), activity (n=8 nonfailing; n=9 SV heart disease), and localization (n=3 SV heart disease) were determined in explanted human right ventricle myocardium. PDE5 is expressed in SV heart disease cardiomyocytes, and PDE5 protein expression and activity are increased in SV heart disease right ventricle compared with nonfailing right ventricle. Isolated neonatal rat ventricular myocytes were treated for 72 hours with nonfailing or SV heart disease patient serum±sildenafil. Reverse transcription quantitative polymerase chain reaction (n=5 nonfailing; n=12 SV heart disease) and RNA sequencing (n=3 nonfailing; n=3 SV heart disease) were performed on serum-treated neonatal rat ventricular myocytes and demonstrated that treatment with SV heart disease sera results in pathological gene expression changes that are attenuated with PDE5i. Conclusions PDE5 is increased in failing SV heart disease myocardium, and pathological gene expression changes in SV heart disease serum-treated neonatal rat ventricular myocytes are abrogated by PDE5i. These results suggest that PDE5 represents an intriguing myocardial therapeutic target in this population.

Identification of Novel Hemostatic Biomarkers of Adverse Clinical Events in Patients Implanted With a Continuous-Flow Left Ventricular Assist Device

Heart failure affects over 5 million people in the United States. Its rising prevalence and the limited supply of donor hearts is increasing the use of mechanical cardiac support with the implantation of continuous-flow ventricular assist devices (CF-VAD). Patients with CF-VAD implants are at risk of complications, specifically adverse hemostatic events such as nonsurgical bleeding and thrombosis. Development of a pump thrombus requires clinical intervention and/or surgical replacement significantly increasing the risk of patient morbidity and mortality. Identification of biomarkers for these events could improve current risk assessment models, subsequent treatment, and quality of life prognoses for VAD-implanted patients. The standard means for identifying thrombus in VAD patients is currently limited to monitoring levels of lactate dehydrogenase (>2× upper limit of normal), which is incapable of predicting a future event, but describes the risk of a present thrombus. Surface-enhanced laser desorption ionization time-of-flight mass spectrometry is a technique used to identify biomarkers. In this study, 3 groups of unique peaks were identified in plasma from patients with left ventricular assist devices: 8.1-kDa, 11.7-kDa, and a 15.2-/16.1-kDa pair. Unique correlations were found for each peak, respectively, with microparticles (MPs) and MP procoagulant activity, C-reactive protein, and MP-tissue factor. Furthermore, the use of 8.1-kDa peaks may be able to differentiate thrombotic events from other hemostatic events.

Defining the molecular signatures of human right heart failure

AIMS

Right ventricular failure (RVF) varies significantly from the more common left ventricular failure (LVF). This study was undertaken to determine potential molecular pathways that are important in human right ventricular (RV) function and may mediate RVF.

MATERIALS AND METHODS

We analyzed mRNA of human non-failing LV and RV samples and RVF samples from patients with pulmonary arterial hypertension (PAH), and post-LVAD implantation. We then performed transcript analysis to determine differential expression of genes in the human heart samples. Immunoblot quantification was performed followed by analysis of non-failing and failing phenotypes.

KEY FINDINGS

Inflammatory pathways were more commonly dysregulated in RV tissue (both non-failing and failing phenotypes). In non-failing human RV tissue we found important differences in expression of FIGF, TRAPPAC, and CTGF suggesting that regulation of normal RV and LV function are not the same. In failing RV tissue, FBN2, CTGF, SMOC2, and TRAPP6AC were differentially expressed, and are potential targets for further study.

SIGNIFICANCE

This work provides some of the first analyses of the molecular heterogeneity between human RV and LV tissue, as well as key differences in human disease (RVF secondary to pulmonary hypertension and LVAD mediated RVF). Our transcriptional data indicated that inflammatory pathways may be more important in RV tissue, and changes in FIGF and CTGF supported this hypothesis. In PAH RV failure samples, upregulation of FBN2 and CTGF further reinforced the potential significance that altered remodeling and inflammation play in normal RV function and failure.

Spermine and spermidine reversed age-related cardiac deterioration in rats

Aging is the most important risk factor for cardiovascular disease (CVD). Slowing or reversing the physiological impact of heart aging may reduce morbidity and mortality associated with age-related CVD. The polyamines, spermine (SP) and spermidine (SPD) are essential for cell growth, differentiation and apoptosis, and levels of both decline with age. To explore the effects of these polyamines on heart aging, we administered SP or SPD intraperitoneally to 22- to 24-month-old rats for 6 weeks. Both treatments reversed and inhibited age-related myocardial morphology alterations, myocardial fibrosis, and cell apoptosis. Using combined proteomics and metabolomics analyses, we identified proteins and metabolites up- or downregulated by SP and SPD in aging rat hearts. SP upregulated 51 proteins and 28 metabolites while downregulating 80 proteins and 29 metabolites. SPD upregulated 44 proteins and 24 metabolites and downregulated 84 proteins and 176 metabolites. These molecules were mainly associated with immune responses, blood coagulation, lipid metabolism, and glutathione metabolism pathways. Our study provides novel molecular information on the cardioprotective effects of polyamines in the aging heart, and supports the notion that SP and SPD are potential clinical therapeutics targeting heart disease.