Myocardiocyte senescence in ischemic heart disease and breathome changes

Abstract

Aging is an irreversible and continuous process characterized by metabolic alterations induced by epigenomic changes. Myocardiocytes, a type of cardiac cell, are among the cells affected by this process. These changes affect cardiometabolic homeostasis at both cellular and subcellular levels. Consequently, dysregulation occurs between the protective and aggressive systems of myocardiocytes, leading to an increased prevalence of the aggressive system. This imbalance weakens the protective system against harmful factors, such as ischemia. As a result, ischemic heart disease develops, and pathological cardiometabolic changes in myocardiocytes progress with each ischemia-reperfusion event. These cardiometabolic alterations serve as biomarkers (outcomes) of ischemic myocardiocytes released into the bloodstream. The detection of these biomarkers in exhaled breath, in the form of volatile organic compounds (VOCs), is feasible using various types of mass spectrometers, including the proton transfer reaction time of flight mass spectrometer. Exhaled VOCs can be utilized as biomarkers of the biological age of myocardiocytes by measuring the concentration of specific VOCs associated with cardiometabolic changes and ischemic myocardiocytes. This article explores the relationship between myocardiocyte aging and the development of ischemic heart disease, as well as the changes in exhaled VOCs.

Key Words: Ischemic heart disease; Breathome; Aging; Atherosclerosis; Metabolome; Lipidome; Myocardiocytes

Core Tip: This mini-review pioneers a novel integrative concept linking myocardiocyte aging, ischemic heart disease pathogenesis, and the emerging field of breathomics. We propose that the metabolic byproducts of senescent myocardiocytes, released into the bloodstream, are detectable as a unique volatile organic compound signature in exhaled breath. This “breathome” offers a potential non-invasive window to directly assess cardiac biological age and ischemic heart disease status, moving beyond traditional risk scores. The article critically explores this missing chain between cellular senescence and breath biomarkers, framing breath analysis as a future tool for diagnostics, risk stratification, and monitoring of anti-senescence therapies in cardiology.

INTRODUCTION

Ischemic heart disease (IHD) is the pathology of our era in the context of mortality and morbidity in the developed and developing countries. IHD is aging dependent, and further exhaled volatile organic compounds (VOCs) are IHD cardiometabolic changes dependent[1].

The development of IHD involves several factors, particularly the aging of myocardiocytes. Digesting the role of myocardiocytes aging in the appearance of IHD can reveal new diagnostic and therapeutic targets through the identification of aging biomarkers. These biomarkers are available in serum and exhaled breath in the form of exhaled VOCs. Various methods exist for detecting exhaled VOCs, including the use of a mass spectrometer known as proton transfer reaction time of flight.

The current methods used for diagnosis and prevention of IHD suffer from bias in the accuracy in determining the risk of development or death due to IHD. Such methods include SCORE2, SCORE2-OP, and the smart risk score, which is used to assess the risk of developing IHD or dying from it in the following years. In addition, stress ECG is one of the methods used to assess the status of IHD and the functional class. However, the diagnostic accuracy does not exceed 60%.

IHD is responsible for approximately 5%-7% of the geriatric population[2,3]. Therefore, a novel strategy must be developed to overcome the high incidence rate and the prevalence of the IHD in society. The strategy must re-evaluate the early detection methods, prevention methods, risk scoring methods, treatment protocols, the patients follow up during the treatment period, the prognosis, and the secondary prevention represented by the recurrence of the angina attack.

Therefore, using another method for an early and accurate assessment of the risk of IHD development is critical. The pathogenesis of IHD, considering the ageing process is the leading pathophysiological change in myocardiocytes in the pathogenesis of IHD. Consequently, examination of exhaled breath changes based on the presence of IHD or its absence.

IHD PATHOPHYSIOLOGY

It is well known that IHD develops due to the reduction in the response of the myocardiocytes’ protective system to damaging factors, including poor nutrition. However, the aging process affects not only the myocardiocytes, it goes beyond that to affect the blood vessels endothelial cells resulting into endothelial dysfunction. Furthermore, the risk of atherosclerotic plaque increases with the damaging the tunica intima of the coronary vessels. The coexistence of significant dyslipidemia improves the rapid formation of the atherosclerotic plaque and deterioration of the myocardiocytes protective system. Therefore, the pathophysiology of IHD is not obligatory due to the independent aging of myocardiocytes. Coronary artery aging can be simultaneously involved in the pathogenesis of IHD in combination with myocardiocytes aging.

Aged cells release biologically active agents and induce the aging process in surrounding cells[4]. Furthermore, due to the heterogeneity of aging phenotypes it is difficult to assess the aging process[5,6]. However, according to Lu et al[7], biological age can be measured using the remaining part of the epigenome in that particular cell.

Therefore, comprehending the potential role of aging in myocardiocytes ischemia is a challenging task and critical to understanding the changes in the exhaled breath analysis.

MYOCARDIOCYTES AGING IN THE PATHOPHYSIOLOGY OF IHD

Aging results in an increase in the level of the reactive oxygen species due to the downregulation of the activity of the cellular (myocardiocytes) antioxidant defense system. Furthermore, impaired coronary vascular status results in poor myocardiocytes nutrition.

A large cohort study of more than 10000 participants for more than 34 years demonstrated that signs on the external outlook of the individual such as frontoparietal baldness, are associated with increase the risk of IHD, as well as other cardiovascular diseases[8]. This supports the hypothesis that aging plays an essential role in the development of IHD.

Previous studies suggested that mitochondrial enzyme arginase-II (Arg-II) and cytosolic isoenzyme arginase-I involved in the myocardiocyte aging process[9,10]. However, current findings demonstrated that the mitochondrial enzyme Arg-II is not expressed in myocardiocytes[11]. Whereas, knockdown of the Arg-II-\- gene in animal models was associated with protective effects on the aged myocardiocytes[11]. Moreover, the effect of Arg-II on myocardiocytes, fibroblasts, and endothelial cells mediated by interleukin (IL)-1β from aging macrophages in non-cell-autonomous effect well as a cell-autonomous effect of Arg-II through mtROS in fibroblasts contributing to cardiac aging phenotype[11].

Aging leads to significant structural changes in cardiomyocytes, including increased cell size, altered inter-organ communication, and mitochondrial fragmentation. These changes impair cell function and contribute to the development of IHD[12,13].

Aging is associated with metabolic reprogramming in the heart, including reduced myocardial lipid catabolism, increased dependence on anaerobic glycolysis, and altered mitochondrial function. These metabolic changes contribute to cellular senescence and cardiac dysfunction[13].

Chronic low-grade inflammation, often called “inflammaging“, is a hallmark of aging and significantly affects cardiovascular health. This inflammation exacerbates the progression of atherosclerosis and IHD[12,14].

The presence of comorbidities such as diabetes, hypertension, and hyperlipidemia complicates the treatment of IHD. Single cardioprotective strategies often do not reach their full potential in patients with these conditions[15].

Moreover, autophagy plays a central role in the aging process that results in the pathogenesis of IHD. Were aged myocardiocytes characterized by altered autophagy, particularly down-regulated autophagy. Furthermore, previous studies have shown that aging is associated with bone marrow alterations that lead to the development of clinically dangerous particles called indeterminate potential[16-20]. Furthermore, aged myocardiocytes characterized by transcriptome and epigenome changes, upregulation of the genes responsible for aging changes on the cellular and subcellular levels. At the same time, down-regulation of the protective ones that are responsible for the youth of myocardiocytes.

It is well established that aging is associated with impaired mitochondrial function and increased production of pro-inflammatory cytokines IL-6 in the vasculature tree. IHD involves disrupted vascular endothelial cells and smooth vascular muscle cells. In this regard, the vasculature and the myeloid cells of the immune system[21] contribute to the pathogenesis of the IHD through the IL-6 signaling pathway (Table 1)[22-62].

Table 1 Myocardiocytes aging in the pathophysiology of ischemic heart disease: Cellular mechanisms, molecular pathways, and clinical implications.

Aging-related cellular change	Key molecular pathways	Clinical implications	Therapeutic targets/strategies	Ref.
Cellular senescence and senescence-associated secretory phenotype	NF-κB, CaMKII, cGAS-STING, TGF-β/transforming growth factor beta-activated kinase 1, p38, phosphatidyl-inositol-3-kinase/Akt/mTOR	Promotes inflammation, impairs repair, worsens outcomes	Senolytics, NF-κB/cGAS-STING inhibitors	Li et al[22], Glück et al[23], Dasgupta et al[24], Li et al[25], Sweeney et al[26], Yan et al[27]
Mitochondrial dysfunction and mPTP	Akt, glycogen synthase kinase-3beta, PKC isoforms, mPTP regulators (cyclophilin D, FoF1 adenosine triphosphate synthase), reactive oxygen species	Increased ischemic injury, reduced tolerance, cell death	Mitochondria-targeted antioxidants, mPTP inhibitors (e.g., cyclosporine A, melatonin)	Mendoza and Karch[28], Liu et al[29], Petrosillo et al[30], Zhu et al[31], Li et al[32]
Impaired autophagy and proteostasis	The mTOR, AMPK, autophagy-lysosome pathway	Accumulation of damaged proteins/organelles, worsened ischemic outcomes	Autophagy inducers (e.g., AMPK activators, H2S)	Leon and Gustafsson[33], Sithara and Drosatos[34], Chen et al[35]
Telomere shortening and apoptosis	The p16INK4a, p53, GDF11, IGF-1, telomerase	Reduced regenerative capacity, increased apoptosis, heart failure	Telomerase activators, IGF-1, GDF11	Torella et al[36], Chen et al[37], Adili et al[38]
Metabolic shifts and energy imbalance	Pyruvate dehydrogenase, protein acetylation, SIRT1, AMPK	Disrupted energy metabolism, increased ischemic susceptibility	SIRT1 activators, metabolic modulators	Sithara and Drosatos[34], Rajakumar et al[39]
Extracellular matrix remodeling and fibrosis	TGF-β, collagen synthesis, matrix metalloproteinases	Increased stiffness, impaired function, adverse remodeling	Anti-fibrotic agents, TGF-β inhibitors	Yan et al[27], Carbonin et al[40], Horn[41], Shih et al[42]
Stem cell senescence and regenerative decline	The p16INK4a, p53, Mybl2, vascular endothelial growth factor	Reduced efficacy of cell therapy, impaired repair	Stem cell rejuvenation (platelet-rich plasma, Mybl2 overexpression)	Torella et al[36], Cianflone et al[43], Khatiwala and Cai[44], Fan et al[45], Wang et al[46], Guo et al[47]
Chronic inflammation and immune infiltration	NF-κB, cGAS-STING, cytokines (IL-1α, IL-8)	Exacerbated injury, adverse remodeling	Anti-inflammatory agents, cGAS-STING inhibitors	Yan et al[27], Guo et al[47], Zhao et al[48], Fang et al[49], Xu et al[50], Wang et al[51]
Impaired cardioprotective signaling	Akt, PKCε, G protein-coupled receptor, circadian genes (Bmal1, Per2)	Loss of ischemic preconditioning, increased injury	PKC/Akt activators, circadian modulators	Honma et al[52], Przyklenk et al[53], Bartling et al[54], Bonney et al[55]
ER stress and mitochondrial crosstalk	ATF6, GRP-78, calpain 1, mitochondria-associated membranes, YAP/SERCA2a	Mitochondrial dysfunction, increased apoptosis	ER stress inhibitors (4-PBA, metformin), calpain inhibitors	Qin et al[56], Yuan et al[57], Chen et al[58], Chen et al[59]
Circadian rhythm disruption	Bmal1, Per2, RCAN1, HDAC3, Rev-erbα	Increased susceptibility, impaired repair	Chronotherapy, melatonin, and REV-ERB agonists	Bonney et al[55], Chen et al[60], Mia et al[61], Nuszkiewicz et al[62]

Akt: Protein kinase B; AMPK: AMP-activated protein kinase; ER: Endoplasmic reticulum; IGF-1: Insulin-like growth factor-1; IL: Interleukin; mTOR: Mammalian target of rapamycin; mPTP: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NF-κB: Nuclear factor kappa B; PKC: Protein kinase C; TGF-β: Transforming growth factor-beta.

BREATHOME IN IHD

Breathomics, also known as the study of the ‘breathome’ is a rapidly emerging field that involves analyzing the VOCs in exhaled breath to diagnose and monitor diseases.

Changes in exhaled VOCs in patients with IHD remain an undeveloped section of the science[63]. Therefore, current hypotheses suggest that changes in exhaled VOCs are due to lipid peroxidation of the ischemic myocardiocytes, dysbiosis of the gut microbiota dysbiosis, and changes in atherosclerotic plaques, separately or simultaneously in eight studies[63-70]. All these pathophysiological changes are associated with the release of metabolites byproducts.

Aging is associated with bio-physiopathomorphological changes, including the modification of the left ventricle function and anatomy as well as the atriums dilatation[71-74]. Furthermore, a heart aged characterized by epicardial torsion and endocardial circumferential shortening and relationship to epicardial subepicardial and subendocardial fiber orientations epicardial[75,76]. Furthermore, senescent heart characterized by aortic valve calcification, fat accumulation around the heart, epicardial fat accumulation, impaired Ca²⁺ cycling/handling (diastolic dysfunction), and cardiac autonomic dysfunction (central integration, impaired baroreceptor output and decreased sinoatrial response)[77-80]. Genetic modifications represented by the shortening of the telomer, DNA damage, mutations, and epigenetic modifications. Cellular changes in myocardiocytes expressed by myocardiocytes hypertrophy, fibroblast over activity (fibrosis), cardiac amyloidosis, and mitochondrion dysfunction[81-84]. Therefore, the breathomics changes in IHD represent several pathophysiological changes related to the aging process of myocardiocytes and the vascular tree.

However, the current understanding of breathomics changes in IHD remains largely inferential and is based on indirect evidence from systemic metabolic alterations[65]. A critical challenge lies in establishing direct causal links between specific exhaled VOCs and defined aging pathways within cardiomyocytes. For instance, while aldehydes such as hexanal and heptanal may indicate lipid peroxidation, their origin could equally reflect hepatic metabolism, gut microbiota activity, generalized systemic oxidative stress rather than exclusive cardiac senescence. Future studies employing isotope tracing, cardiac-specific knockout models, and simultaneous multi-omics profiling of cardiac tissue and exhaled breath are essential to deconvolute the cardiac contribution to the breath volatilome and validate its specificity as a biomarker of myocardial aging (Figure 1).

Figure 1 The potential origin of the volatile organic compounds in the exhaled breath of aged myocardiocytes. PTR-TOF-MS: Proton transfer reaction time-of-flight mass spectrometry; VOCs: Volatile organic compounds.

THE MISSING CHAIN BETWEEN THE BREATHOME BEHAVIOR IN IHD PATIENTS AND MYOCARDIOCYTES AGING

Aging has been confirmed to be part of the crime of IHD development[81]. However, the relation between aging and IHD and changes in the exhaled VOCs has not been explored.

Myocardiocytes are highly specialized cells stuck in the G1, G2 phase of cell life. Therefore, there is no chance for proliferation at a level to fit the losses. Simultaneously, the protective defense system of the myocardiocytes can effectively remove intracytoplasmic metabolic toxic byproducts such as oxidative stress metabolites. Furthermore, aged myocardiocytes play an important role in damaging healthy surrounding myocardiocytes (bystander effect) through the release of the pro-oxidant phenotype and the secretion of a wide range of pro-inflammatory cytokines, chemokines, matrix metalloproteinases and growth factors, termed the secretory phenotype that can promote senescence in surrounding cells[4].

SENOLYTICS EFFECT ON BREATHOME BEHAVIOR

There have been several biological agents to slow or reduce the aging process in the cells. Several antisenescent drugs have been checked for their efficacy for clinical and subclinical use during different pathologies such as kinase inhibitors, Bcl2 family protein inhibitors, naturally occurring polyphenols, heat shock protein inhibitors, BET family protein inhibitors, P53 stabilizers, repurposed anti-cancer drugs, cardiac steroids, peroxisome proliferator-activated receptor alpha agonists and antibiotics[85].

To date, there are no specific cardiac senolytics that can slow or reduce the aging process of the myocardiocytes[85].

Myocardiocytes aging and the development of IHD present significant challenges, including structural and metabolic changes, chronic inflammation, and the presence of comorbidities. However, future potential lies in anti-senescence therapies, metabolic interventions, multi-target strategies, and regenerative medicine. Breathomics, despite its current challenges, hold promise as a non-invasive diagnostic tool for cardiovascular diseases. Continued research and technological advancements are essential to overcoming these challenges and harness the full potential of these emerging fields.

CURRENT CHALLENGES AND FUTURE POTENTIALS: MYOCARDIOCYTES AGING-IHD-BREATHOME

The primary challenge in this area is understanding the complex mechanisms of myocardiocytes aging and how it contributes to IHD. Aging myocardiocytes undergo various changes, including alterations in gene expression, accumulation of damaged proteins and organelles, and reduced regenerative capacity. These changes can lead to impaired heart function and increased susceptibility to IHD. However, the exact mechanisms are still not fully understood, which hinders the development of effective treatments.

Despite these challenges, breathomics has significant potential for the future. It offers a noninvasive, rapid, and potentially cost-effective method for disease diagnosis and monitoring. It could be particularly useful for diseases that currently require invasive tests for diagnosis or monitoring. Furthermore, with advances in analytical techniques and data analysis methods, the accuracy and utility of breathomics are likely to improve in the future.

The translation of breathomics into clinical practice faces several formidable challenges. First, there is a lack of standardized protocols for breath sample collection, storage, and analysis, leading to significant inter-study variability. Second, exhaled VOC profiles are highly susceptible to confounding by diet, medication, environmental exposures, and circadian rhythms, complicating data interpretation[63]. Third, as noted, the specificity of VOCs for cardiac aging vs concurrent systemic processes (e.g., hepatic steatosis, renal dysfunction, or intestinal dysbiosis) remains unproven[63]. Finally, extensive multi-center validation studies with longitudinal design are imperative to confirm the clinical utility, accuracy, and prognostic value of exhaled VOC signatures in IHD[63].

DISCUSSION

It is well known that IHD develops due to the reduction in the response of the myocardiocytes protective system to damaging factors, including poor nutrition[86]. However, the aging process affects not only the myocardiocytes, but it also goes beyond that to affect the blood vessels endothelial cells resulting in endothelial dysfunction. Furthermore, the risk of atherosclerotic plaque increases with the damaging the tunica intima of the coronary vessels. The coexistence of significant dyslipidemia improves the rapid formation of the atherosclerotic plaque and deterioration of the myocardiocytes protective system.

Therefore, the pathophysiology of IHD is not obligatory due to the independent myocardiocytes aging. Coronary artery aging can be simultaneously involved in the pathogenesis of IHD pathogenesis with myocardiocytes aging.

According to recent findings, the use of lens age can be a biomarker of IHD[87]. A recent cohort retrospective study demonstrated that elevated modified Healthy Aging Index is associated with increase the risk of IHD in 36%; adjusted hazard ratio = 1.36 (95%CI: 1.33-1.39)[88]. Interestingly, findings suggested that the existence of IHD accelerates neurocytes aging process[89].

It is important to note that the hypothesis connecting breath VOC changes directly to cardiomyocyte senescence in IHD, while physiologically plausible, remains a proof-of-concept requiring empirical validation. The complex, systemic nature of VOC production necessitates careful discrimination of cardiac-specific signals from background metabolic noise.

CONCLUSIONS

Each living object is subject to an aging process. Aging is a characteristic of life, and each cell will face the end of death. However, some cells experience a slow aging process that prolongs their life. Unfortunately, myocardiocytes are highly sensitive cells and are dramatically affected by aging process and external damaging factors such as ischemia. The aging process exposes myocardiocytes to damage due to the low degree of ischemia. These changes can be expressed in the exhaled breath in the form of exhaled VOCs. However, the exact exhaled VOCs are not established and have yet to be investigated. An ongoing clinical trial is conducted to assess exact exhaled VOCs in patients with IHD (NCT06181799).

In summary, this review proposes a novel integrative framework linking cardiomyocyte senescence, IHD pathophysiology, and breathomics – positioning exhaled VOCs as a potential non-invasive window into cardiac biological age. While this conceptual model is supported by converging lines of indirect evidence, it also highlights a significant ‘black box’ between molecular aging mechanisms and detectable breath biomarkers. Therefore, this manuscript serves less as a definitive account and more as a translational roadmap and a call for interdisciplinary collaboration. Future research must prioritize: (1) Mechanistic studies to trace VOC origins to specific cardiac aging pathways; (2) Development of standardized breath analytical platforms; (3) Rigorous clinical validation in diverse cohorts; and (4) Integration of breathomics with other digital and molecular biomarkers. Through such efforts, the vision of breath-based monitoring of cardiac aging and IHD risk may transition from compelling hypothesis to clinical reality.