Trained Immunity in Cardiovascular Health: Mechanisms, Clinical Implications, and Future Directions

Abstract

Trained immunity, the enhanced innate immune response following a primary stimulus, has emerged as a pivotal concept in understanding inflammation-driven cardiovascular diseases (CVDs). Distinct from classical immunological memory of adaptive immunity, trained immunity involves epigenetic and metabolic reprogramming of innate immune cells, rendering them more responsive to subsequent challenges. This article reviews current evidence on the role of trained immunity in cardiovascular health, elucidating its mechanisms, epidemiological relevance, clinical features, diagnostic approaches, management strategies, recent advances, and guideline-based recommendations. The review highlights the translational potential of targeting trained immunity in CVD prevention and therapy, while critically discussing existing knowledge gaps and future research priorities for clinicians and researchers.

Introduction

Cardiovascular diseases remain the leading cause of morbidity and mortality globally, contributing to an estimated 17.9 million deaths annually. The multifactorial nature of CVDs encompasses genetic, environmental, metabolic, and immunological components. In recent years, the concept of trained immunity a form of innate immune memory involving monocytes, macrophages, and natural killer cells has gained attention for its role in perpetuating chronic inflammation associated with atherosclerosis and other cardiovascular pathologies. Unlike adaptive immunity, trained immunity is characterized by long-term functional reprogramming of innate cells through epigenetic modifications and metabolic rewiring. This review synthesizes recent scientific and clinical findings on trained immunity in cardiovascular health, offering mechanistic insights and discussing clinical implications for contemporary practice.

Epidemiology / Disease Burden

The global burden of cardiovascular diseases is heavily influenced by low-grade chronic inflammation, with atherosclerosis serving as a prime example. Epidemiological studies have demonstrated that heightened inflammatory markers, such as high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6), are associated with increased risk of myocardial infarction, stroke, and heart failure. The prevalence of CVDs is higher in populations with chronic infectious and metabolic conditions, which are now recognized to induce trained immunity. The persistent inflammatory state resulting from trained immunity may explain the residual cardiovascular risk observed even after optimal control of traditional risk factors. Thus, understanding the epidemiological footprint of trained immunity provides valuable context for CVD prevention strategies.

Pathophysiology

Trained immunity is initiated when innate immune cells encounter specific stimuli such as β-glucans, oxidized low-density lipoprotein (oxLDL), or Bacillus Calmette–Guérin (BCG) vaccine leading to durable epigenetic changes, including histone modification and DNA methylation. These changes enhance the transcriptional response upon subsequent exposures. In the vasculature, trained monocytes and macrophages exhibit amplified pro-inflammatory cytokine production, increased foam cell formation, and heightened endothelial activation, contributing to the initiation and progression of atherosclerotic plaques. Metabolic reprogramming, particularly a shift toward glycolysis and altered cholesterol metabolism, further augments the inflammatory phenotype. Animal models and human studies have confirmed that trained immunity accelerates atherogenesis and plaque instability, underscoring its pathogenic significance in CVDs.

Risk Factors

Several clinical and environmental factors potentiate trained immunity and thereby increase cardiovascular risk. Chronic infections (e.g., cytomegalovirus, periodontal pathogens), metabolic syndromes (obesity, diabetes mellitus), hypercholesterolemia, and exposure to air pollutants and dietary factors (e.g., Western diet rich in saturated fats) have all been implicated in inducing or sustaining trained immunity. Genetic predispositions such as polymorphisms in NOD2 or TLRs may further alter the susceptibility of innate cells to reprogramming. These risk factors not only promote a pro-inflammatory milieu but also impair the resolution of inflammation, thereby sustaining the cycle of vascular injury and repair characteristic of atherothrombosis.

Clinical Features

The clinical manifestations of trained immunity in cardiovascular health are largely indirect, manifesting as accelerated atherosclerosis, increased incidence of acute coronary syndromes, recurrent myocardial infarction, and chronic heart failure. Patients often exhibit persistent elevation of inflammatory biomarkers despite standard therapy. Subclinical disease may present as endothelial dysfunction or increased arterial stiffness, detectable through imaging and functional assays. Importantly, trained immunity contributes to non-resolving inflammation in patients with established CVD, correlating with a higher risk of adverse cardiovascular events and poorer prognosis.

Diagnosis

Currently, no single diagnostic test specifically identifies trained immunity in clinical practice. However, surrogate markers such as persistent elevation of hsCRP, IL-6, or tumor necrosis factor-alpha (TNF-α) in the absence of acute infection or overt autoimmune disease are suggestive. Advanced techniques, including transcriptomic and epigenomic profiling of monocytes, are being explored in research settings. Functional assays that evaluate cytokine responses to ex vivo restimulation of monocytes or macrophages are emerging as potential diagnostic adjuncts. Imaging modalities, such as PET-CT using tracers for vascular inflammation, may indirectly reflect the burden of trained immunity-driven pathology.

Treatment & Management

Management strategies for mitigating the impact of trained immunity in cardiovascular health are evolving. Conventional approaches include aggressive control of modifiable risk factors lipids, blood pressure, glycemic status, and lifestyle modification. Statins not only lower cholesterol but also exert anti-inflammatory effects, partially attenuating trained immunity. Novel agents, such as interleukin-1β inhibitors (e.g., canakinumab) and colchicine, have shown benefit in reducing cardiovascular events in patients with persistent inflammation. Immunomodulatory diets (Mediterranean diet, increased omega-3 fatty acid intake) and weight reduction also provide adjunctive benefits by dampening innate immune activation. However, targeted therapies that specifically reverse trained immunity are still under investigation.

Recent Advances / Emerging Therapies

Recent advances include the development of small molecule inhibitors targeting epigenetic enzymes (e.g., bromodomain and extra-terminal domain inhibitors) to reverse the trained phenotype in monocytes. Preclinical studies suggest that modulation of the mevalonate pathway and metabolic checkpoints (e.g., mTOR inhibitors) can attenuate trained immunity and reduce atherogenesis. Therapeutic vaccines designed to induce tolerance rather than training are being explored. Furthermore, the application of single-cell multi-omics is unraveling the heterogeneity of trained immune responses, paving the way for precision medicine approaches. Ongoing clinical trials are evaluating the efficacy of these innovative therapies in reducing cardiovascular events in high-risk populations.

Guideline Recommendations

While major cardiovascular guidelines (ACC/AHA, ESC) emphasize the importance of inflammation in CVD pathogenesis, specific recommendations targeting trained immunity are not yet established. However, recent consensus encourages the use of anti-inflammatory therapies (e.g., statins, canakinumab, colchicine) in patients with elevated inflammatory biomarkers and residual risk. Lifestyle interventions, such as dietary modification and smoking cessation, remain cornerstone recommendations. Guidelines also advocate for the integration of emerging biomarkers and novel risk stratification tools as evidence matures. Multidisciplinary care involving cardiology, immunology, and primary care is recommended for optimal implementation of these strategies.

Conclusion

Trained immunity represents a paradigm shift in our understanding of cardiovascular disease pathogenesis, offering novel mechanistic insights and therapeutic opportunities. The interplay between innate immune memory and vascular inflammation underscores the need for innovative diagnostic and management approaches. While current evidence supports the clinical relevance of trained immunity, further studies are needed to translate these findings into practice-changing interventions. A deeper mechanistic understanding and the development of targeted therapies promise to reduce the global burden of CVDs driven by chronic inflammation and innate immune dysregulation.