Cardioprotection induced by repetitive ischemia/reperfusion (I/R) is not confined to the ischemic region but may extend to distant myocardial territories, a phenomenon termed intracardiac remote ischemic preconditioning (icRIPC). The present study aimed to evaluate the delayed effects of icRIPC on infarct size (IS), left ventricular (LV) function (LVF), and myocardial gene and protein expression. icRIPC was induced in 13 pigs by 3 cycles of 10 min ischemia/10 min reperfusion of the left anterior descending coronary artery (LAD) (conditioning) territory, followed 24 h later by reperfused acute myocardial infarction (AMI) of the left circumflex artery (LCx) (infarcted) territory, induced by 90-min percutaneous balloon occlusion of the mid LCx followed by reperfusion (group icRIPC-AMI). Thirteen additional pigs underwent a sham icRIPC procedure followed by reperfused LCx AMI 24 h later and served as controls (group AMI). Five pigs from each group were euthanized at 3 days, and myocardial expression of nine selected genes was quantified by RT-qPCR in the distal LAD and LCx territories. Protein expression of the two significantly upregulated genes was assessed by Western blot. The remaining eight pigs in each group were followed for 1 month. At 3 days after reperfused AMI, superoxide dismutase-2 (SOD2) protein expression was increased in the infarcted LCx territory of the icRIPC-AMI group, whereas inducible nitric oxide synthase (iNOS/NOS2) protein expression was increased in the distal LAD territory. At 1 month, IS was lower in the icRIPC-AMI than in the AMI group (8.4±3.7
Malonate, an inhibitor of mitochondrial succinate dehydrogenase (SDH), protects against ischemia–reperfusion injury (IRI) when given at early reperfusion, making it a promising therapeutic agent for acute myocardial infarct (AMI) and stroke patients. Prior to clinical studies, it is essential to identify potential translational roadblocks. One such barrier is the metabolic signature of the heart. Here, we explored whether and how the metabolic signature of the heart drive cardiac IRI and modulate malonate protection. Langendorff-perfused mouse hearts were subjected to 30 min ischemia (I) followed by 90 min reperfusion (R), with or without 5mM disodium malonate administered during the first 5 min reperfusion. Cardiac IRI and malonate protection were examined under four metabolic conditions increasing in metabolic complexity: glucose-only (G), glucose + glutamine (GG), GG + fatty acid (F), F + insulin (Ins). Metabolomic profiling and survival kinases were evaluated at end-ischemia and at 7 min of reperfusion ± malonate. Additional experiments examined the effects of glucose, lactate, and low pH on malonate efficacy. IRI (
During heart failure (HF), gene and protein expression profiles undergo extensive compensatory and pathological remodeling. We previously observed that fast skeletal myosin binding protein-C (fMyBP-C) is upregulated in diseased mouse hearts. While fMyBP-C shares significant homology with its cardiac paralog, cardiac myosin binding protein-C (cMyBP-C), there are key differences that may affect cardiac function. However, the consequence of cardiac expression of fMyBP-C is unknown. Here, we aim to elucidate the impact of fMyBP-C expression on cardiac function and pathology. To determine the sufficiency of fMyBP-C to cause cardiac dysfunction, we generated cardiac-specific fMyBP-C over-expression mice. These mice were crossed into cMyBP-C null mice to assess the effect of fMyBP-C in the complete absence of cMyBP-C. Finally, fMyBP-C null mice underwent transverse aortic constriction (TAC) to define the requirement of fMyBP-C in HF. We confirmed the upregulation of fMyBP-C in several models of cardiac disease, including lineage tracing models. Low levels of fMyBP-C caused mild cardiac remodeling and sarcomere dysfunction. Exclusive expression of fMyBP-C in a HF model exacerbated cardiac pathology. Furthermore, reduction of fMyBP-C expression by shRNA in HF improved cardiac function. Following pressure overload, fMyBP-C null mice demonstrated greater resistance to cardiac decompensation. Mechanistically, our data suggest the differential regulation of the myosin super-relaxed state by cMyBP-C and fMyBP-C plays a contributing role. These findings suggest the elevated expression of fMyBP-C in diseased hearts is a pathological response. Targeted therapies to prevent upregulation of fMyBP-C may prove beneficial in the treatment of HF.
Myocardial ischemia/reperfusion (I/R) injury constitutes a major clinical challenge in ischemic heart disease, and ferroptosis has been recognized as a core driver of cardiomyocyte death during reperfusion. However, the upstream regulatory network governing myocardial ferroptosis remains incompletely defined. The mitogen-activated protein kinase 14 (p38α, MAPK14) is a stress-activated kinase critically involved in cardiac pathophysiology, yet its role in I/R-induced ferroptosis remains unclear. Here, we report that p38α deficiency attenuates ferroptosis and protects against myocardial I/R injury by stabilizing c-Myc. Phosphorylated p38α (p-p38α) was significantly elevated in mouse hearts after I/R and in cardiomyocytes following oxygen–glucose deprivation/reperfusion (OGD/R). Cardiomyocyte-specific p38α knockout markedly reduced ferroptosis, myocardial infarct size, and cardiac dysfunction. Mechanistically, p-p38α interacts with c-Myc under I/R stress via key residues Arg291, Arg300, and Lys304 of c-Myc and promotes the recruitment of the E3 ubiquitin ligase STUB1, thereby enhancing ubiquitination at Lys51 (K51) of c-Myc and its proteasomal degradation. Loss of p38α stabilizes c-Myc protein and reverses this process. Furthermore, c-Myc acts as a transcriptional repressor of NCOA4, a core mediator of ferroptosis. I/R-induced downregulation of c-Myc relieves NCOA4 suppression, triggering iron overload, lipid peroxidation, and ferroptosis. Overexpression of c-Myc or inhibition of STUB1 or NCOA4 abolished the pro-ferroptotic effect of I/R. Pretreatment with the p38α inhibitor VX-745 recapitulated the cardioprotective effects by restoring the p38α/c-Myc/NCOA4 axis in vivo. Collectively, our findings identify the p38α/c-Myc/NCOA4 signaling axis as a regulatory cascade governing myocardial I/R-induced ferroptosis. These findings nominate the p38α/c-Myc/NCOA4 axis as a potential therapeutic target in myocardial I/R injury.
In contrast to humans, zebrafish hearts after cryoinjury undergo transient fibrotic scarring that subsequently resolves and renews with functional cardiomyocytes. To understand the molecular mechanisms underlying cardiac scarring and fibrotic resolution in zebrafish, we investigated cardiac transcriptomic responses in zebrafish at 14 days post-cryoinjury. Principal component analyses revealed distinct transcriptome clusters corresponding to healthy and injured hearts, highlighting significant changes during cardiac regeneration. Gene set enrichment analyses indicated that extracellular matrix organization and inflammatory response pathways were activated in cryoinjured hearts, while mitochondrial organization and oxidative phosphorylation pathways were downregulated. Notably, miR-145-5p was downregulated and col5a1 upregulated in the cryoinjured hearts, contrasting with the expression patterns of miR-145-5p and COL5α1 in the left ventricles of ischemic cardiomyopathy patients. Prediction of miRNA-mRNA interaction and a dual luciferase assay identified COL5A1 as a target of miR-145-5p. Inhibition of miR-145-5p in human cardiac fibroblasts increased COL5A1 and α-SMA, decreased COL1A, and stimulated fibroblast differentiation, proliferation, and migration. Conversely, overexpression of miR-145-5p led to the opposite effects. Downregulation of COL5A1 suppressed fibroblast proliferation and migration, which could be rescued by inhibition of miR-145-5p. Moreover, downregulation of col5a1 attenuated cardiac fibrotic scar resolution in zebrafish. Interestingly, downregulation of COL5A1 or inhibition of miR-145-5p diminished the expression of integrin subunits ITGβ3 and ITGβ5. Furthermore, inhibition of miR-145-5p potentiated the suppression of TGF-β/SMAD signalling and the enhancement of fibroblast proliferation mediated by inhibiting integrin αvβ3 and αvβ5 with cilengitide. Collectively, miR-145-5p modulates collagen production and fibroblast behaviour partially via targeting COL5A1 and through integrin-mediated pathways.
After myocardial infarction (MI), the heart undergoes a reparative process that includes an initial acute inflammatory phase followed by a subsequent reparative phase. The transition between these phases is crucial for cardiac recovery, but the key factors remain unclear. Meteorin-like (Metrnl) promotes anti-inflammatory/reparative macrophage polarization in the myocardium, yet its role in the acute phase post-MI is unknown. We observed that macrophages infiltrating the ischemic myocardium produced elevated levels of Metrnl in both the heart and circulation 4 days post-MI. The absence of Metrnl in Metrnl⁻/⁻ mice altered myocardial healing and remodeling, with an increased presence of macrophages with a more pro-inflammatory phenotype. Conversely, cardiac Metrnl overexpression restored myocardial repair and promoted a shift toward a more anti-inflammatory/reparative macrophage phenotype. Mechanistically, Metrnl regulated macrophage-dependent production of Oncostatin M (Osm), a key cytokine in the early inflammatory phase post-MI that induces cardiomyocyte production of Reg3β. Reg3β, in turn, limits pro-inflammatory macrophage activation and polarization while modulating their trafficking, ultimately influencing the duration and intensity of the pro-inflammatory phase post-MI. Thus, Metrnl plays a crucial role in cardiac repair by modulating the acute phase following myocardial infarction through its regulation of macrophage populations.
Sympathetic overactivity and gut microbiota dysbiosis drive chronic heart failure (CHF) progression. This study explored the associations of mesenteric denervation (MDN) with cardioprotection and potential involvement of the nerve–microbiota–heart axis in MI-induced CHF mice. C57BL/6 mice were randomized into control, CHF, and CHF_MDN groups. CHF was induced by LAD ligation, and MDN was performed via phenol ablation of the superior mesenteric artery. MDN was associated with suppressed mesenteric sympathetic activity, improved left ventricular ejection fraction, and reduced myocardial fibrosis and serum BNP. MDN correlated with restoration of colonic tight junction protein expression, reduced myocardial NLRP3 inflammasome activation, and decreased systemic inflammation (LPS, TNF-α, IL-6). 16S rRNA sequencing showed MDN reshaped gut microbiota (decreased F/B ratio, increased facultative anaerobes). Untargeted metabolomics identified 30 differential metabolites in CHF_MDN mice; MDN reduced pro-inflammatory metabolites (hippuric acid, deoxycholic acid) and increased metabolites linked to energy metabolic reprogramming (2-hydroxybutyric acid, ketoleucine, acetylglycine). Integrated analysis revealed that Campylobacterota and Halobacterota (altered by MDN) correlated with sarcosine and linoleic acid. MDN improves cardiac function in MI-induced CHF, alongside inhibition of mesenteric sympathetic activity, restoration of intestinal barrier function, reduction of inflammation, and modulation of gut microbiota and metabolic profiles. These findings suggest the nerve–microbiota–heart axis as a potential therapeutic target.
The only way to salvage myocardium from infarction is timely reperfusion of the occluded coronary artery. Timely reperfusion reduces infarct size and mortality. The history of reperfusion therapy from the first clinical use of intravenous streptokinase in patients with acute myocardial infarction by Sherry et al. in the late 1950s, over seminal experimental dog studies by Ross Jr. et al., demonstrating infarct size reduction by timely reperfusion in the early 1970s, to a more systematic use of initially streptokinase and a later tissue plasminogen activator in clinical trials (GISSI, TIMI), the addition of platelet inhibition (ISIS) and ultimately mechanical recanalization by percutaneous coronary intervention with stenting, is reviewed in detail. Cardioprotection beyond timely reperfusion was first demonstrated in the seminal experimental dog studies of ischemic conditioning by Murry, Reimer, and Jennings in the 1980s and initiated a tsunami of experimental studies in various experimental models to identify the underlying signal transduction, but has not yet been established in clinical practice. Clinical trials on various forms of ischemic conditioning, potentially cardioprotective drugs and transcutaneous vagal nerve stimulation, are still underway.
Compared to classic myocardial infarction (cMI), myocardial infarction with non-obstructive coronary arteries (MINOCA) is characterized by symptoms consistent with acute coronary syndrome, but without demonstrable coronary obstruction. Therefore, its diagnosis remains challenging and often relies on cardiac magnetic resonance imaging (MRI), which is usually performed only days after the index event, leading to delayed diagnosis and initiation of therapy. Coronary microembolization (CME) has been described as one of the major pathologies underlying MINOCA. However, the molecular mechanisms of CME remain poorly understood, resulting in a lack of rapid diagnostic tools and specific therapy approaches. In this review, we describe the molecular underpinnings of CME-derived MINOCA: an inflammatory environment inducing significant cellular damage that is conserved between cMI and MINOCA. While we note that some of these inflammatory and cellular death pathways are shared with cMI, we dissect mechanistic distinctions in CME-derived MINOCA such as dysregulated immune responses and higher miRNA activity. Most importantly, as molecular treatments for MI are currently in late-stage clinical trials, we can thus differentiate which therapeutics may work better for MINOCA. Thus, these findings can be used as a roadmap for diagnostic biomarkers and targeted therapeutic approaches for MINOCA.
Off-pump coronary artery bypass grafting (OPCABG) is associated with increased platelet aggregation and a higher incidence of postoperative atrial fibrillation (POAF). Remote ischemic preconditioning (RIPC) has been reported as a promising intervention to mitigate these adverse outcomes. Consecutive patients with cytochrome P450 family 2 subfamily C member 19 (CYP2C19) loss-of-function (LOF) genotype who underwent isolated OPCABG were randomly assigned to receive intermittent ischemia–reperfusion applied to the arm (RIPC group) or not intervention (control group). RIPC was performed after induction of anesthesia using three cycles of 5-min inflation separated by 5-min deflation. The primary outcome was the cumulative incidence of POAF within the first postoperative week, assessed by the intention-to-treat analysis. Secondary outcomes included POAF burden, biochemical indicators, and clinical trajectory. Among the 220 patients available for the primary endpoint analysis, POAF occurred in 27 of 109 patients (24.8
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold significant promise for cardiac regeneration therapies. However, the efficacy of such treatments depends on the ability of transplanted cells to migrate and integrate into the damaged myocardium, a process that remains poorly understood. In this study, we investigated the migratory behaviour of hiPSC-CMs using homogenised rat MI tissue to simulate myocardial infarction (MI) in vitro. Transwell migration assays demonstrated a concentration-dependent chemotactic response, with hiPSC-CM migration increasing up to threefold towards MI tissue homogenate. Wound-healing assays further confirmed enhanced migration under MI-mimetic conditions. Bulk RNA sequencing revealed activation of the TGF-β signalling pathway as a key regulator of this response. Inhibition of TGF-β signalling, both pharmacologically and through antibody neutralisation, significantly reduced hiPSC-CM migration. These findings uncover a previously underappreciated chemotactic capability of hiPSC-CMs and identify TGF-β signalling as a central mediator, offering new mechanistic insights and potential therapeutic targets to improve the integration and efficacy of hiPSC-CM-based cardiac regeneration strategies.
Barth Syndrome (BTHS) is an inherited mitochondrial cardiomyopathy caused by variants in the gene encoding TAFAZZIN (Taz), a transacylase catalyzing the synthesis of the essential mitochondrial phospholipid cardiolipin (CL). Although defects in Taz deteriorate mitochondrial respiration, Ca2+-uptake, and redox regulation in cardiac myocytes, we previously observed an unexpected lack of oxidative cardiac damage, despite the development of cardiomyopathy in a BTHS mouse model with Taz-knockdown (KD). Furthermore, we revealed that the integrated stress response (ISR) governs metabolic rewiring in Taz-KD hearts to compensate for deficient mitochondrial FAO and to support GSH production. Here, we interrogated whether adaptive mechanisms in peroxisomes, which are closely associated with mitochondria and harbor antioxidative enzymes, can also compensate for the mitochondrial defects. We identified alterations in the peroxisomal biogenesis factors PEX14 and PEX19, indicating changes in the peroxisomal proteome in Taz-KD vs. WT hearts. While the enzymes of peroxisomal FAO were unchanged, levels of Lon Protease 2 (LONP2) and catalase were elevated in Taz-KD hearts. Inhibition or siRNA-mediated knockdown of catalase increased reactive oxygen species (ROS) and blunted the protection of mouse embryonic fibroblasts (MEF) with Taz-knockout (KO), but not in WT, from ROS-induced activation of the apoptotic caspase 3. Furthermore, we observed that the increase in plasmalogen synthesis in cardiac Taz-KD peroxisomes contributes to the activation of the ISR, since siRNA-mediated knockdown of the key enzyme GNPAT blunted the ISR and thereby increased cellular ROS in Taz-KO, but not WT MEFs. In conclusion, peroxisomes facilitate a counterregulatory response to dysfunctional mitochondria by activating a catalase-driven ROS defense and maintaining ISR-mediated metabolic alterations, both of which compensate for mitochondrial dysfunction and oxidative stress. Therefore, the so far poorly investigated mitochondrial-peroxisome crosstalk may represent a novel therapeutic target in an orphan disease with a poor prognosis.
Calcific aortic valve stenosis is the most common valvular heart disease requiring treatment. Although both tricuspid (AVS) and bicuspid (bAVS) aortic valve stenoses become calcified and functionally impaired in advanced stages, the pathophysiology of these conditions remains unclear. We investigated this using a multitechnology approach on explanted AVS, bAVS, and aortic regurgitation (AR) control valves. Because of technical limitations in processing heavily calcified aortic valve tissue, we established Kawamoto’s film method for human aortic valve tissue, enabling the production of well-preserved cryosections and high-quality immunostainings. Both bulk RNA-seq analysis and immunostainings revealed that angiogenesis, inflammation, and calcification are key features distinguishing bAVS from AVS. In fact, we found that angiogenic genes and CD31+ cells, as well as inflammatory genes and CD45+ cells, are significantly elevated in bAVS. The most striking difference between bAVS and AVS was the prominent expression of specific genes involved in tissue calcification, such as matrix metallopeptidase 12 (MMP12), dentin matrix acidic phosphoprotein 1 (DMP1), and proteoglycan 4 (PRG4), along with approximately 1.7-fold increased calcification as shown by micro-CT and von Kossa staining analysis in bAVS. These findings were corroborated in a retrospective analysis of 1108 AVS and bAVS patients who underwent transcatheter aortic valve implantation (TAVI). The bAVS patients exhibited significantly stronger aortic valve calcifications (1.6-fold) but a significantly lower vascular calcification burden. These data further suggest that AVS and bAVS are distinct disease entities, with bAVS exhibiting increased local inflammation, angiogenesis, and calcification, findings that may guide future therapeutic strategies.
Clinical trial experience supports the use of myosin inhibitors in hypertrophic cardiomyopathy (HCM), while early proof-of-concept studies suggest potential benefit in selected patients with heart failure with preserved ejection fraction (HFpEF). However, concerns about systolic dysfunction arising from their negative inotropic effects may limit broader application. In a series of in vivo and in vitro experiments in healthy animal preparations, we investigated how aficamten, a next-generation cardiac myosin inhibitor, interacts with key determinants of myocardial contractile function. Echocardiographic examinations in sedated Wistar rats revealed that bolus administration of aficamten (2 mg·kg−1 i.v.) did not reduce cardiac output (CO) at pacing frequencies of 300 and 400 bpm, despite marked increases in end-diastolic (ED) and end-systolic left ventricular (LV) volumes and the associated decrease in LV ejection fraction (EF). In field-stimulated intact cardiomyocytes from Mongrel dogs, increasing aficamten concentrations (0.1–1 µM) decreased contraction amplitude and diastolic duration. These effects occurred across pacing frequencies (0.25–1.25 Hz) and in the absence of aficamten-specific changes in intracellular Ca2+ transients. In permeabilized LV cardiomyocytes from dog and rat hearts, aficamten decreased active force production (Fmax) and its Ca2+ sensitivity under isometric conditions in a similar manner. Importantly, the sarcomere length dependence of Fmax was preserved, while the length-dependent increase in Ca2+ sensitivity was attenuated at higher (0.1–0.2 µM) aficamten concentrations in both species. Our findings in healthy myocardium characterize aficamten as a myosin inhibitor that increases diastolic chamber volumes through reduced contractility, with diastolic function indices (i.e. E/e', IVRT) reflecting the expected hemodynamic consequences of increased preload rather than direct impairment of myofibrillar relaxation. This enhanced preload recruits preserved sarcomere length-dependent force generation to compensate for negative inotropy, thereby maintaining stroke volume and cardiac output.
Senescent endothelial cells (ECs), characterized by a reduced angiogenic and regenerative potential, are key players in the pathophysiology of cardiovascular diseases. Therefore, targeting these cells has been suggested as an effective therapeutic strategy to increase health. Here, we are the first to report that non-genetic overexpression of the Yamanaka factors induces partial functional rejuvenation and attenuation of senescence-associated features in endothelial cells. Methods to characterize the effects of the transient reprogramming included quantification of gene expression as well as measurements of cellular functions in vitro. Further, in vivo experiments were performed in a hind-limb ischemia model. The application of the pharmacological cocktail to replicative senescent ECs resulted in a robust but timely restricted activation of Oct3/4, Sox2, Klf4, and c-Myc (p < 0.0 and p < 0.01). This was associated with a significant reduction of senescence markers such as p16ink4a and p14arf (p < 0.01). Additionally, qPCR-based telomere length measurements were stabilized, and functional properties of senescent ECs, such as proliferation, migration, sprouting, and tube formation, were improved (p < 0.05). Continuous cultivation of the treated cells over the long term indicated that expression of p16ink4a and p14arf remained significantly low, while cell migration remained enhanced. In vivo, a significantly improved blood flow was observed at 7 and 14 days after hind-limb ischemia in 21 months old C57BL/6 mice (p < 0.001). In conclusion, we revealed that a partial attenuation of endothelial cell senescence-associated features can be induced by a short pharmacological overexpression of the Yamanaka factors. While the compounds used are individually approved for other indications, their combined use in this context highlights a conceptual translational potential, whereas the clinical applicability of this approach remains to be evaluated.
The coronary microvascular plexus responds to cardiac ischemia through angiogenic neovascularization in the ischemic and border zones to sustain the demand for oxygen and nutrients. Although new blood vessels form, the process of endothelial maturation and extent to which the post-injured microvascular plexus resembles the pre-injured state is unclear. Developmental processes suggest that neovascular endothelial cells must specify toward arterial or venous fates to generate a continuum of heterogenous identities across the microvascular plexus. Therefore, we investigated whether coronary endothelial cells undergo similar arterial-venous specification after ischemia and return to a pre-injured maturation state. Cardiac single-cell RNA sequencing datasets from a murine myocardial infarction model isolated over time post-injury were analyzed for endothelial cell fate dynamics through gene expression and cell trajectory. We found that murine coronary endothelial cells undergo arterial-venous specification at later time points following ischemia-induced angiogenesis. However, post-injured endothelial cells express a reduction of genes associated with arterial-venous identity and blood vessel development with early dysregulation of signaling pathways required for arterial-venous specification. These transcriptional changes are associated with disrupted heterogeneity of the post-injured microvascular plexus and a shift toward venous fate. Endothelial cells in cardiac tissue of ischemic cardiomyopathy patients also mirror the disrupted gene patterns, signaling pathways, and venous-shifted heterogeneity. Using primary human coronary microvascular endothelial cells, we identified that arterial identity is promoted by TGF signaling and inhibited by WNT signaling. Finally, spatial sequencing datasets from human ischemic cardiomyopathy of different injured cardiac zones identified that the venous-shifted maturation state is enriched in the border zone and associates with POSTN expression. These results suggest that the post-injured coronary microvascular plexus is driven to a venous-shifted fate in the border zone, revealing disrupted arterial-venous heterogeneity as a potential hallmark of ischemic heart failure.
Neuroimmune communication is essential for regulating inflammation and maintaining cardiovascular homeostasis, but the role of sensory pathways in this process is poorly understood. Arterial baroreceptors are typically defined as mechanoreceptors essential for arterial pressure homeostasis and have been associated with modulation of the immune response. However, their role in sensing systemic inflammation remains unknown. Here, we establish the molecular profile of the rat aortic depressor nerve (ADN) as an immune-competent tissue and investigate its response to lipopolysaccharide (LPS)-induced endotoxemia. Using analysis of gene expression, total protein quantification, and immunofluorescence assay, we demonstrate that the ADN, from male Sprague–Dawley rats (7–8 weeks old), constitutively expresses key components for innate immune signalling, including Toll-like receptor 4 (TLR4), MyD88, and phosphorylated NF-κB, indicating a state of constant immunological vigilance. LPS administration induced an inflammatory response within the ADN, upregulating gene expression of NF-κB, interleukin-6, and type I interleukin 1 receptor, and it also increased the ADN electrical activity. Notably, the increase in nerve firing occurred while the animals were experiencing systemic hypotension and also during the diastolic phase, indicating that this response is not from the mechanosensory reflex. Furthermore, we characterized the progression of this immune response in the nodose ganglion and aortic arch, identifying a coordinated neuroimmune sensory axis. These findings reposition arterial baroreceptors from purely mechanoreceptors to integrative immunosensors that actively detect and respond to systemic inflammation. This novel neuroimmune circuit represents a critical link between inflammation and cardiovascular system, offering a novel therapeutic target for treating cardiovascular and inflammatory conditions.
In murine coxsackievirus B3 myocarditis, the most widely used experimental model of viral myocarditis, functional alterations such as reduced cardiac output are frequently interpreted as surrogates of myocardial injury and inflammation, despite concurrent systemic illness. The relative contribution of systemic disease processes to these functional changes remains poorly defined. We therefore aimed to disentangle myocardial and systemic drivers of cardiac dysfunction using a microRNA-guided viral detargeting approach. We engineered a cardiomyocyte-detargeted virus by inserting target sequences for the muscle-enriched microRNA-1 into the viral genome, selectively suppressing viral replication in cardiac muscle while largely preserving systemic infection. This enabled direct comparison between conventional myocarditis and cardiac-attenuated infection in mice, using serial echocardiography as the primary non-invasive functional readout of cardiac performance. Day 3 post infection was analyzed as the acute phase and day 7 as a later stage associated with peak myocardial inflammation. Cardiac viral titers were profoundly reduced by detargeting (approximately 3-log at day 3 and 6-7-log at day 7), accompanied by absence of troponin T release, inflammatory cell infiltration, and histological myocarditis. Despite this, cardiac output was reduced at day 3 and remained impaired at day 7 in both groups. This reduction was associated with decreased left ventricular end-diastolic volume, while ejection fraction remained preserved. At day 3, additional reductions in cardiac output and global longitudinal strain were observed in control-virus-infected mice. At day 7, cardiac output remained comparably reduced despite marked differences in myocardial injury. These findings demonstrate that systemic infection substantially contributes to impaired cardiac function and that echocardiographic readouts reflect a composite phenotype. Functional alterations should therefore be interpreted in the context of systemic effects and integrated with cross-organ analyses to enable accurate interpretation in preclinical myocarditis models.
Renal denervation (RDN) has emerged as a potential therapeutic strategy to modulate autonomic imbalance and attenuate inflammation in cardiovascular disease. However, the mechanisms underlying its cardioprotective effects remain incompletely understood. In this study, we evaluated the functional and molecular effects of RDN in a rabbit model of experimental autoimmune myocarditis (EAM). A total of twenty-four male New Zealand white rabbits were randomly assigned to four groups: control, EAM, EAM with RDN for 4 weeks (EAM-RDN4W), and EAM with RDN for 6 weeks (EAM-RDN6W). Echocardiographic assessment demonstrated that EAM induced marked systolic dysfunction, as reflected by a reduction in left ventricular ejection fraction (LVEF) (approximately 65
Effective treatments for heart failure with preserved ejection fraction (HFpEF) are limited. Empagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, provides cardiovascular benefits for patients with HFpEF. SGLT2 expression is virtually absent in cardiomyocytes, hence the exact protective mechanism of empagliflozin is unclear. We aimed to study the effect of in vivo empagliflozin treatment on excitation–contraction coupling (ECC), electrophysiology, and gene transcription in a translational two-hit HFpEF mouse model that combines the obese-diabetic leptin receptor-deficient db/db mice with chronic aldosterone infusion (db/db + Aldo). We performed morphometry, echocardiography, cardiomyocyte electrophysiology, intracellular Ca2+ imaging, and whole-heart RNA-sequencing in empagliflozin-treated db/db + Aldo and vehicle control mice. In db/db + Aldo mice, empagliflozin (in vivo, 4 weeks) reduced the elevated plasma blood glucose (13 ± 5 mmol/L versus 23 ± 8 mmol/L) and BNP levels, prevented pulmonary congestion, and ameliorated diastolic dysfunction. However, empagliflozin did not reduce cardiac hypertrophy and obesity. In healthy control mice, empagliflozin had no functional effect. Chronic in vivo empagliflozin treatment in db/db + Aldo also normalized the changes in cardiomyocyte electrophysiology and Ca2+ handling properties measured in the absence of empagliflozin in the perfusion solution during cell experiments, indicating a true phenotypic rescue. Differentially expressed gene clusters were identified characteristic of the db/db genotype, aldosterone, and empagliflozin treatments. Interestingly, empagliflozin did not just reverse the HFpEF-altered gene expression but shifted it further away from control to a new expression profile. We conclude that chronic in vivo empagliflozin treatment restores cardiomyocyte electrophysiological and ECC properties, ameliorates diastolic function in cardiometabolic HFpEF, and induces complex gene expression changes.
