Epicardial fat, the visceral adipose tissue enveloping the myocardium, has garnered increasing attention as an active endocrine organ rather than a mere energy storage depot. It secretes a variety of bioactive molecules, including adipokines, cytokines, and metabolites that can influence underlying cardiac structures. The present study elucidates how epicardial fat influences the lymphatic system within the heart, disrupting its metabolic homeostasis and thereby contributing to the pathogenesis of atrial fibrillation.

The lymphatic system in the heart is critical for maintaining fluid balance, immune cell trafficking, and the clearance of metabolic waste products. Lymphatic vascular dysfunction can lead to edema, inflammation, and ultimately impair cardiac conduction systems, facilitating arrhythmogenesis. Despite mounting evidence implicating epicardial fat in cardiac diseases, the mechanisms linking it to lymphatic dysfunction have remained obscure until now.

An intensive biochemical analysis identified kynurenic acid as a pivotal mediator secreted by epicardial adipose tissue. Kynurenic acid arises from the kynurenine pathway, the principal route of tryptophan catabolism. It functions as an endogenous antagonist for excitatory amino acid receptors and participates in modulating oxidative stress and inflammation. This study uncovered that elevated kynurenic acid levels, emanating from epicardial fat, negatively impact lymphatic endothelial cell metabolism, disrupting energy homeostasis and lymphatic drainage capacity.

To investigate these phenomena, the researchers employed a multifaceted approach combining human cardiac tissue samples, animal models of atrial fibrillation, and in vitro cellular assays. Metabolomic profiling of epicardial fat samples from patients with atrial fibrillation revealed significantly higher kynurenic acid concentrations compared to controls. This aberrant metabolic signature correlated positively with markers denoting lymphatic dysfunction, such as lymphatic leakage and impaired lymphangiogenesis.

In preclinical models, administration of kynurenic acid recapitulated lymphatic metabolic disturbances characteristic of those observed in atrial fibrillation. Notably, kynurenic acid altered mitochondrial bioenergetics in lymphatic endothelial cells, reducing ATP production and increasing reactive oxygen species generation. These cellular derangements culminated in compromised lymphatic contractility and structural integrity, hallmark features of lymphatic vascular insult.

The mechanistic dissection further demonstrated that kynurenic acid acts via binding to the G protein-coupled receptor 35 (GPR35) expressed on lymphatic endothelial cells. Activation of GPR35 triggered downstream signaling cascades that impaired mitochondrial function and remodeled the cytoskeletal architecture, weakening endothelial barrier properties. Importantly, pharmacological inhibition of GPR35 rescued mitochondrial bioenergetics and restored lymphatic function in experimental models, highlighting its potential as a drug target.

In the context of atrial fibrillation, these lymphatic perturbations facilitate a pro-inflammatory microenvironment conducive to electrical remodeling of atrial myocytes. The study posits that the ensuing structural and electrical remodeling lowers the threshold for arrhythmic events. Correspondingly, human atrial tissue from patients exhibited elevated expression of inflammatory cytokines alongside kynurenic acid accumulation, linking epicardial fat metabolism with electrophysiological abnormalities.

These findings fundamentally shift the understanding of atrial fibrillation pathogenesis, framing epicardial fat not merely as a passive risk factor but as an active driver of lymphatic metabolic dysfunction through kynurenic acid signaling. This paradigm underscores the need to consider metabolic and immunologic crosstalk between cardiac adipose depots and lymphatic vasculature when developing antiarrhythmic therapies.

The therapeutic implications are far-reaching. Targeting the kynurenine pathway to modulate kynurenic acid production or antagonizing GPR35 signaling within the cardiac lymphatic endothelium could restore lymphatic metabolic balance and attenuate arrhythmogenic substrate formation. Future clinical trials may explore selective enzyme inhibitors or receptor antagonists to prevent or reverse atrial fibrillation progression.

Moreover, this work highlights the value of metabolomics and receptor biology in delineating complex cardiac disease mechanisms. By integrating molecular, cellular, and physiological data, the study provides a holistic model of epicardial fat-induced lymphatic dysfunction as a pathogenic axis in atrial fibrillation. This approach fosters precision medicine strategies tailored to patient-specific metabolic profiles.

The study also raises intriguing questions about systemic metabolic alterations in atrial fibrillation and the possible roles of kynurenic acid beyond the heart. Given kynurenic acid’s immunomodulatory properties, its impact on systemic inflammation and other cardiovascular comorbidities merits further scrutiny. Understanding how epicardial fat-derived metabolites interact with distant organs could reveal novel links between metabolic syndrome and arrhythmia.

Furthermore, the discovery of GPR35 as a mediator introduces a new player in cardiac lymphatic biology. Previously underappreciated in cardiovascular contexts, GPR35 may serve broader functions in endothelial metabolism and immune cell recruitment. Demystifying its ligands and downstream effectors will expand insights into vascular health and disease.

Technological advances enabling high-resolution imaging and metabolic flux analysis were instrumental in this research. Employing cutting-edge live-cell mitochondrial assays and sophisticated in vivo models allowed the precise quantification of lymphatic metabolic impairment induced by kynurenic acid. These methodologies set a precedent for future investigations dissecting cardiac microenvironment interactions.

In summary, Takahashi, Abe, Yoshida, and colleagues have unveiled a novel metabolic interplay between epicardial adipose tissue and cardiac lymphatic function mediated by kynurenic acid. This biochemical pathway emerges as a crucial factor in the etiology of atrial fibrillation, providing a promising target for innovative therapeutic strategies. Through cellular bioenergetic disruption and receptor-mediated signaling cascades, kynurenic acid orchestrates lymphatic dysfunction that fosters arrhythmogenic conditions, fundamentally redefining how adipose tissue influences cardiac electrophysiology.

The convergence of adipose-derived metabolites, lymphatic vasculature, and electrical remodeling spotlighted in this work underscores the complexity of atrial fibrillation beyond traditional electrophysiological paradigms. As this research advances, it holds transformative potential to refine diagnosis, risk stratification, and treatment of arrhythmias, translating molecular insights into clinical breakthroughs. The elucidation of epicardial fat’s role in modulating cardiac lymphatic metabolism heralds a new frontier in cardiovascular science.

Subject of Research: Metabolic and molecular mechanisms by which epicardial fat influences cardiac lymphatic function in atrial fibrillation.

Article Title: Kynurenic acid mediates epicardial fat-induced lymphatic metabolic dysfunction in atrial fibrillation.

Article References: Takahashi, M., Abe, I., Yoshida, N. et al. Kynurenic acid mediates epicardial fat-induced lymphatic metabolic dysfunction in atrial fibrillation. Nat Commun (2026). https://doi.org/10.1038/s41467-026-72974-9

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Non-coding RNAs, encompassing microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and transfer RNA-derived fragments (tRFs), are increasingly recognized for their roles in regulating diverse biological pathways. Unlike the traditional focus on protein-coding genes, ncRNAs orchestrate gene expression at transcriptional and post-transcriptional levels, influencing cell fate decisions, immune responses, and tissue remodeling. Recent research indicates that these molecules could offer unprecedented insights into NEC’s underlying molecular cascades, given their involvement in key inflammatory, apoptotic, angiogenic, and immune pathways.

The inflammatory milieu in NEC is notably complex, with excessive immune cell infiltration driving tissue destruction. MicroRNAs, for example, have been identified as critical regulators of inflammatory cytokines and signaling networks within NEC-affected intestines. Specific miRNAs may modulate toll-like receptor pathways and downstream effectors such as NF-κB, shaping the intensity and duration of inflammatory responses. By altering the expression of these miRNAs, it might be possible to dampen harmful inflammation while preserving essential host defenses, thus providing a new therapeutic axis to mitigate intestinal injury.

Long non-coding RNAs, a less studied class, exhibit versatile interaction capacities with DNA, RNA, and proteins, contributing to chromatin remodeling and transcriptional regulation. In NEC, lncRNAs appear to influence angiogenic responses necessary for intestinal repair by modulating vascular endothelial growth factors (VEGFs) and their receptors. Impaired angiogenesis exacerbates tissue ischemia, contributing to necrotic lesions; thus, lncRNA-mediated control of vascular processes may be essential to restoring gut integrity.

Adding another layer of complexity are the recently discovered tRNA-derived fragments, small ncRNAs generated through specific cleavage of tRNAs. These fragments have been implicated in modulating cellular stress responses and apoptosis, processes intimately linked with the pathophysiology of NEC. By regulating stress granule formation and mitochondrial function, tRFs may influence how preterm gut epithelial cells respond to hypoxic and inflammatory insults.

A particularly exciting avenue in NEC research involves the profiling of ncRNA signatures within affected tissues and systemic circulation. Distinct patterns of miRNAs, lncRNAs, and tRFs have been correlated with histopathological severity, suggesting their utility as biomarkers that can predict disease onset or progression. Plasma-derived exosomal ncRNAs, which are stable and readily accessible, offer a non-invasive window into intestinal health. Their detection could revolutionize early diagnosis, allowing clinicians to intervene before irreversible damage ensues.

Moreover, human milk has emerged as a natural reservoir of protective exosomal microRNAs. These miRNAs, delivered to the neonate through breastfeeding, may confer resilience against NEC by modulating host immune responses and enhancing epithelial barrier function. Understanding the specific miRNA profiles present in human milk could pave the way for therapeutic supplementation strategies, especially in infants unable to receive maternal milk.

Intriguingly, the interplay between ncRNAs and the gut microbiome is gaining recognition as a critical determinant of NEC susceptibility. Microbial metabolites and ncRNA expression patterns appear to influence one another bidirectionally, shaping immune tolerance and inflammatory responses in the immature intestine. This crosstalk opens the possibility of manipulating microbiome-ncRNA interactions to create a protective environment against NEC development.

Despite these promising insights, significant challenges remain. The heterogeneity of NEC pathophysiology complicates the identification of consistent ncRNA biomarkers applicable across diverse patient populations. Additionally, functional characterization of numerous lncRNAs and tRFs in intestinal development and injury responses is still in its infancy. These gaps necessitate larger-scale studies employing high-throughput sequencing technologies capable of capturing the full spectrum of ncRNA expression and their intricate regulatory networks.

Advances in single-cell sequencing and spatial transcriptomics offer powerful tools to delineate the cellular origins and targets of ncRNAs within the NEC-affected intestine. Mapping these molecules in situ will enhance understanding of their precise roles across different cell types, including enterocytes, immune cells, and endothelial populations, giving rise to more targeted and effective interventions.

The integration of multi-omics approaches combining ncRNA profiling with epigenomics, proteomics, and metabolomics will provide a holistic view of NEC pathogenesis, integrating molecular signals into coherent biological pathways. Such integrative analyses have the potential to identify master regulatory nodes amenable to therapeutic modulation, driving the field toward biomarker-guided precision medicine.

Current therapeutic strategies targeting ncRNAs are still experimental but hold immense promise. Synthetic miRNA mimics or inhibitors (antagomirs) could be designed to restore balances in deleterious signaling pathways, while delivery systems such as engineered exosomes could provide targeted transport to the inflamed gut mucosa, minimizing off-target effects. The safety and efficacy of such approaches in the fragile preterm infant population remain critical challenges to overcome.

In conclusion, non-coding RNAs represent an exciting and rapidly evolving domain within NEC research. Their multifaceted roles in orchestrating inflammation, cell death, repair, and immune modulation position them as both biomarkers for early detection and targets for innovative therapies. Ongoing research promises to transform NEC from a devastating neonatal condition into a disease that can be predicted, prevented, and precisely treated, improving outcomes for the most vulnerable infants.

As scientific understanding continues to advance, collaborations across neonatology, molecular biology, microbiology, and bioinformatics will be paramount. The translation of ncRNA discoveries into clinical practice requires rigorous validation in large, multi-center cohorts and carefully designed trials that address the unique challenges of preterm infants. Achieving this goal could redefine neonatal care, ushering in an era where molecular diagnostics and targeted treatments drastically reduce NEC’s toll on infants and families worldwide.

The future of NEC management lies in harnessing the power of the smallest molecular actors: non-coding RNAs. By illuminating their regulatory codes and leveraging their therapeutic potential, we stand at the precipice of a new paradigm—one where early biomarkers and novel interventions can save lives and prevent lifelong complications caused by this devastating disease.

Subject of Research:
The role of non-coding RNAs as biomarkers and therapeutic targets in the pathogenesis and management of necrotizing enterocolitis in preterm infants.

Article Title:
Emerging role of non-coding RNAs as biomarkers and therapeutic targets in preterm infants with necrotizing enterocolitis.

Article References:
Garg, P.M., Malhotra, A. Emerging role of non-coding RNAs as biomarkers and therapeutic targets in preterm infants with necrotizing enterocolitis. Pediatr Res (2026). https://doi.org/10.1038/s41390-026-04992-8

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DOI:
https://doi.org/10.1038/s41390-026-04992-8