Heart failure with preserved ejection fraction (HFpEF) exhibits an inflammatory‐metabolic phenotype in association with multiple factors. Among them, epicardial adipose tissue (EAT), a type of visceral adipose tissue surrounding the heart, has been gaining attention. EAT expansion is associated with the development of HFpEF, the increased risk for heart failure–related mortality in patients with HFpEF, independent of age, body mass index, diabetes, and sex. Thus, reducing EAT expansion has been proposed as a promising therapeutic strategy for treating HFpEF. Although specific treatment for EAT expansion is unavailable, modulating the inflammatory response and systemic energy metabolism are beneficial in improving clinical symptoms or prognosis in patients with HFpEF. To further enhance our capacity in effectively treating HFpEF, this review discusses the knowledge gaps between EAT expansion and the lack of a platform to reduce EAT expansion in HFpEF, including the choices of appropriate animal models, the conceptual mechanisms of glucose and lipid metabolism in EAT expansion toward potential strategies for selective EAT‐targeted therapeutic avenues.

The epidermal growth factor receptor (EGFR/ErbB1) is a critical regulator of cellular proliferation and differentiation. While its role in oncology is well-characterized, its contribution to glucose homeostasis has emerged as a significant area of metabolic research. This mini-review synthesizes current evidence regarding the seven EGFR ligands—EGF, TGFα, amphiregulin, HB-EGF, betacellulin, epiregulin, and epigen—in regulating beta cell mass, insulin secretion, hepatic gluconeogenesis, and peripheral insulin sensitivity. We critically evaluate the transition from mechanistic in vitro studies to preclinical rodent models, while acknowledging the current lack of human clinical validation. Furthermore, we discuss the metabolic paradox of EGFR tyrosine kinase inhibitors (TKIs) and the safety considerations regarding the mitogenic potential of these ligands. By highlighting emerging evidence and structural innovations such as chimeric ligands, this review provides a roadmap for future translational research in the EGFR/ErbB metabolic signaling axis.

While the cardioprotective role of heat shock proteins (HSPs) in cardiovascular diseases is well established, the isoform-specific functions of HSP70 members in ischemia-reperfusion (I/R) injury remain unclear. This study investigates the role of Hspa1b, a stress-inducible HSP70 isoform, in cardiac I/R injury and elucidates its underlying mechanisms. In vivo, male C57BL/6 J mice were subjected to myocardial I/R surgery. In vitro, H9C2 cardiomyocytes were transfected with siRNA targeting Hspa1b or p53 and subjected to a hypoxia/reoxygenation (H/R) model. Cellular injury was quantified via lactate dehydrogenase (LDH) release, while viability was assessed using the CCK-8 assay. Apoptotic (Bax, Bcl2, and cleaved Caspase3) and ferroptotic (GPX4, XCT/SLC7A11) markers were analyzed by Western blotting. We found that I/R injury in mouse hearts upregulated Hspa1b and p53 protein levels, accompanied by increased infarct size and elevated plasma CK-MB levels. Similarly, H/R treatment in H9C2 cells increased Hspa1b and p53, which coincided with increased apoptosis and ferroptosis. Knockdown of Hspa1b exacerbated H/R-induced cellular injury, as evidenced by further increases in LDH release and reductions in cell viability, and amplified the changes in apoptotic and ferroptotic markers. Crucially, co-silencing Hspa1b and p53 partially rescued these effects, restoring cell viability and suppressing death pathways. Hspa1b confers cardioprotection against H/R injury by suppressing p53-mediated apoptosis and ferroptosis. These findings identify Hspa1b as a key protective regulator that mitigates I/R injury through dual regulation of cell death pathways.

While genome-wide association studies have linked the human PLAC9 gene to body mass index, its physiological function remains largely unexplored. This study identifies PLAC9 as a novel adipokine that is enriched in the stromal vascular fraction of adipose tissue. Its circulating levels correlate with key metabolic dysregulation markers in humans and mice. We utilized gain- and loss- of function approaches in diet-induced obesity (DIO) and streptozotocin (STZ)-induced diabetic mouse models to demonstrate that PLAC9 is a critical regulator of systemic metabolism. Notably, knockdown of endogenous PLAC9 exacerbated metabolic impairments, while its overexpression significantly mitigated DIO-associated metabolic dysregulation. Additionally, recombinant PLAC9 protein administration alleviated hyperglycemia in insulin resistant and insulin deficient models. Mechanistically, PLAC9 potentiated calcium dependent insulin secretion in pancreatic beta cells, promoted glucose uptake in the liver and skeletal muscle, and upregulated hepatic Ghr and Igf1 levels to facilitate glucose homeostasis. Based on these hormone-like properties, we propose renaming the protein Placin. Collectively, these findings establish Placin as a promising therapeutic target, offering translational potential for the management of both type 2 and type 1 diabetes.

BACKGROUND:White adipose tissue (WAT) communicates with distal metabolic organs and regulates their functions by secreting adipokines. Subcutaneous WAT (sWAT) is thought to be metabolically protective but prone to dysfunction with aging and obesity. Chronic activation of p53 is commonly observed in dysfunctional WAT at different anatomical locations in metabolic diseases. However, the impact of MDM2 deletion and its associated p53 activation in sWAT on adipokine profile and systemic metabolism is unknown. METHODS AND RESULTS:To investigate the effects of selective MDM2 deletion and its associated p53 activation in sWAT, we administered two independent adipotropic adeno-associated virus (AAV) vectors expressing Cre recombinase into the sWAT of Mdm2flox/flox mice to locally delete MDM2, a well-established negative regulator that targets p53 for degradation. Deletion of MDM2 resulted in sustained p53 activation, leading to senescence, apoptosis, and fibrosis in sWAT, but not in other fat depots or metabolic organs. sWAT dysfunction resulting from MDM2 deletion and its associated p53 activation had no obvious impact on systemic glucose or lipid metabolism, but progressively triggered hepatic inflammation, damage, and fibrosis. Proteomic analysis revealed that MDM2 deletion shifted the sWAT adipokine profile toward a more pro-inflammatory and pro-fibrotic state. Among the MDM2 deletion-induced sWAT-derived factors, galectin-3 acted as a major contributor to hepatic stellate cell activation and fibrogenesis via STAT3 signaling. At the molecular level, p53 bound to the Lgals3 promoter and upregulated its mRNA expression, thereby increasing galectin-3 secretion primarily in mature adipocytes. CONCLUSION:Our findings reveal that sWAT dysfunction caused by MDM2 deletion and its associated p53 activation is sufficient to promote hepatic damage and fibrosis.

Ethnopharmacological relevance In traditional Chinese medicine (TCM) theory, both heart failure with preserved ejection fraction (HFpEF) and metabolic dysfunction-associated fatty liver disease (MAFLD) are commonly associated with the syndrome of “qi stagnation and blood stasis,” which manifests as cardiac dysfunction and hepatic metabolic disturbance, respectively. Taohong Siwu decoction (THSWD), a classic TCM formula documented in Yi Zong Jin Jian for promoting blood circulation and resolving stasis, is therefore a rational candidate to address this shared pathological basis. While THSWD’s separate benefits for heart and liver have been reported, its potential to treat the interconnected pathology of HFpEF-associated MAFLD remains unexplored. Aim of the study This study aimed to investigate THSWD's therapeutic potential against HFpEF-associated MAFLD and its molecular mechanisms. Materials and Methods A two-hit HFpEF model was established in female mice. Hepatic lipid accumulation was evaluated by measuring triglyceride content, along with Oil Red O and H&E staining. THSWD constituents were identified by UPLC-Q-ToF/MS, and molecular targets were predicted through network pharmacology integrated with RNA-seq of liver tissues, then validated by qPCR and Western blotting. An in vitro steatotic HepG2 model further evaluated the effects of THSWD on lipid accumulation. Results THSWD significantly reduced hepatic lipid accumulation in HFpEF mice. UPLC-Q-ToF/MS identified 51 compounds in THSWD. Network pharmacology suggested these compounds target multiple lipid metabolism genes, particularly via the AMPK pathway. RNA-seq confirmed downregulation of key lipogenic SREBP1-regulated lipogenic genes (Acaca, Fasn, Scd1), validated by qPCR and Western blotting. In steatotic HepG2 cells, THSWD reduced lipid accumulation via AMPK/SREBP1 signaling, as this effect was abolished by either AMPK selective inhibitor or AMPKα1/α2 siRNA knockdown. Furthermore, when SREBP1 knockdown was combined with THSWD treatment, no additive effect on lipid reduction was observed compared to THSWD alone, indicating that SREBP1 mediates the lipid-lowering action of THSWD as a key downstream effector. Conclusion This study provides the first evidence that THSWD alleviates HFpEF-associated MAFLD by suppressing lipid biosynthesis through AMPK/SREBP1 signaling, highlighting its potential as a therapeutic strategy for hepatic steatosis in HFpEF.

Doxorubicin (DOX)-induced cardiotoxicity (DIC) is known to be associated with reduction of cardiac protein kinase C epsilon (PKC-ε). PKC-ε promotes cell survival and protects hearts against various stresses. However, it is unclear whether or not the reduction in cardiac PKC-ε expression plays a causal role in DIC and in particular the potential underlying mechanism whereby PKC-ε may protect against DIC. C57BL/6 mice (8–10-week-old) were either treated with DOX administered intraperitoneally for a duration of 4 weeks to produce cardiotoxicity, or untreated in which mice received the same volume of saline. In vitro, neonatal rat ventricle cardiomyocytes were exposed to DOX for 24 h in the absence or presence of adenovirus overexpressing PKC-ε. Cardiomyocytes in a subgroup were treated with sirtuin-1 (SIRT1) selective inhibitor Ex527. Four weeks after DOX, cardiac contractile function was decreased concomitant with increased serum CK-MB and LDH levels as well as increases in Bax-to-Bcl-2 ratio and Cleaved Caspase 3 proteins expression, while PKC-ε and Sirt1 protein expressions were significantly decreased. In vitro, DOX reduced cardiomyocyte PKC-ε and SIRT1 protein expression, decreased cardiomyocyte viability, and increased LDH release with concomitant increases in oxidative stress and apoptosis. These changes were attenuated by overexpression of PKC-ε. IP study showed that PKC-ε could directly or indirectly bind SIRT1 in cardiomyocytes, and the protect effects of PKC-ε were further canceled by SIRT1 inhibition. In conclusion, activating SIRT1 may represent a major mechanism whereby PKC-ε protects the heart against DOX-induced cell apoptosis and oxidative stress. Graphical Abstract Dox induces cardiotoxicity via inhibiting PKC-epsilon/Sirt1 signaling which can be reversed by PKC-epsilon overexpression.

Stroke poses a significant public health challenge, especially in China, where geographical disparities in incidence rates suggest environmental, genetic, and lifestyle influences on stroke risk. Traditional diagnostic methods, while effective, have limitations that can hinder timely treatment. This study investigated the clinical significance and diagnostic utility of the biomarkers C-reactive protein (CRP), osteopontin (OPN), osteoprotegerin (OPG), and lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) in relation to atherosclerosis and stroke, aiming to enhance early diagnosis and treatment strategies. In this retrospective analysis of 156 patients with arterial stenosis leading to ischemic stroke, data on medical history, lifestyle, serum markers, and comorbidities were collected. Carotid artery stenosis was evaluated using Doppler ultrasound, and the plaque stability and stenosis degree were categorized for analysis. Biomarker levels were measured and analyzed using binary logistic regression and support vector machine optimization models to explore their correlation with stroke. Our findings indicate nuanced roles for CRP, OPN, OPG, and LOX1 in stroke risk, with CRP and OPG acting as protective factors against carotid artery occlusion, and OPN and LOX1 presenting as risk factors. This study underscores the complexity of atherosclerosis and highlights potential therapeutic targets. By elucidating the associations of these biomarkers with atherosclerosis leading to stroke, this study contributes to a better understanding of stroke etiology and opens avenues for the development of more effective diagnostic tools and treatment protocols. Further research, including longitudinal studies and clinical trials, is essential to confirm these findings and to explore their therapeutic implications.

Intestinal function and white adipose tissue (WAT) function deteriorate with age, but whether and how their deterioration is intertwined remains unknown. Increased gut permeability, microbiota dysbiosis, and aberrant immune microenvironment are the hallmarks of intestinal dysfunctions in aging. Here, we show that subcutaneous WAT dysfunction triggered aging-like intestinal dysfunctions in mouse models. Removal of inguinal subcutaneous WAT (iWAT) increased intestinal permeability and inflammation and altered gut microbiota composition as well as susceptibility to pathogen infection in mouse models. These intestinal dysfunctions were accompanied by a reduction of immunoglobulin A-producing (IgA-producing) cells and IgA biosynthesis in the lamina propria of the small intestine. Retinoic acid (RA) is a key cargo within iWAT-derived extracellular vesicles (iWAT-EVs), which, at least in part, elicits IgA class-switching and production in the small intestine and maintains microbiota homeostasis. RA content in iWAT-EVs and intestinal IgA biosynthesis are reduced during aging in mice. Replenishment of "young" iWAT-EVs rejuvenates intestinal IgA production machinery and shifts microbiota composition of aged mice to a "youth" status, which alleviates leaky gut via RA. In conclusion, our findings suggest that iWAT-EVs with RA orchestrate IgA-mediated gut microbiota homeostasis by acting on intestinal B cells, thereby maintaining intestinal health during aging.

BackgroundStroke-associated pneumonia (SAP) often occurs after ischemic stroke. A deterioration in SAP manifests itself in a decreased partial pressure oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio, indicating gas exchange dysfunction. We aimed to investigate independent predictors and outcomes of SAP with low PaO2/FiO2 ratio among patients with acute large vessel occlusion (ALVO) undergoing endovascular therapy.MethodsWe retrospectively analyzed the prospective data of consecutive adult post-interventional patients with ALVO admitted to neuro-intensive care units in Wuhan No. 1 Hospital from December 2020 to December 2022. Patients developing SAP without coronavirus disease 2019 were included in this study and divided into two subgroups: PaO2/FiO2 ratio > 240 and ≤ 240. The primary outcome was favorable neuro-function at 90 days (modified Rankin Scale score of 0–2). Secondary outcomes included hospitalization days, occurrence of symptomatic intracerebral hemorrhage, and 90-day mortality. The independent risk factors and prognosis for SAP with PaO2/FiO2 ratio ≤ 240 were identified by logistic regression analyses.ResultsA total of 159 subjects developing SAP were included in this study: 53 with PaO2/FiO2 ratio > 240 and 106 with ratio ≤ 240. Compared to subjects with PaO2/FiO2 ratio > 240, those with PaO2/FiO2 ratio ≤ 240 had older ages, higher baseline National Institutes of Health Stroke Scales scores, larger proportions of baseline Glasgow Coma Scale (GCS) score of 3–8 and grade of kobuta water swallow test ≥ 3, higher white blood cell (WBC) counts (all p values <0.05). The independent predictors for SAP with PaO2/FiO2 ratio ≤ 240 included ages (adjusted odds ratio [OR], 1.043; 95% confidential interval [CI], 1.011–1.077; p = 0.009), baseline GCS scores of 3–8 (adjusted OR, 2.802; 95% CI, 1.214–6.465; p = 0.016), and ln-transformed WBC counts after SAP diagnosis (adjusted OR, 3.977; 95% CI, 1.226–12.896; p = 0.021). SAP with PaO2/FiO2 ratio ≤ 240 was robustly associated with longer hospitalization days (adjusted OR, 1.074; 95% CI, 1.01–1.143; p = 0.024).ConclusionSAP with PaO2/FiO2 ratio ≤ 240 is shown in significant relevance to the prolonged in-hospital stays among post-interventional patients. Older ages, baseline GCS scores of 3–8, and higher WBC counts after SAP diagnosis can independently predict the occurrence of SAP with a lower PaO2/FiO2 ratio. Further validation studies are needed.

Myocardial infarction (MI) remains a leading cause of mortality worldwide. Despite patients with MI benefit from timely reperfusion therapies, the rates of mortality and morbidity remain substantial, suggesting an enduring need for the development of new approaches. Molecular mechanisms underlying myocardial ischemic injury are associated with both cardiomyocytes and non-cardiomyocytes. Exosomes are nano-sized extracellular vesicles released by almost all eukaryotic cells. They facilitate the communication between various cells by transferring information via their cargo and altering different biological activities in recipient cells. Studies have created great prospects for therapeutic applications of exosomes in MI, as demonstrated through their beneficial effect on heart function and reducing ventricular remodeling in association with fibrosis, angiogenesis, apoptosis, and inflammation. Of note, myocardial ischemic injury is primarily due to restricted blood flow, reducing oxygen availability, and causing inefficient utilization of energy substrates. However, the impact of exosomes on cardiac energy metabolism has not been adequately investigated. Although exosomes have been engineered for targeted delivery to enhance clinical efficacy, challenges must be overcome to utilize them reliably in the clinic. In this review, we summarize the research progress of exosomes for MI with a focus on the known and unknown regarding the role of exosomes in energy metabolism in cardiomyocytes and non-cardiomyocytes; as well as potential research avenues of exosome-mitochondrial energy regulation as well as therapeutic challenges. We aim to help identify more efficient molecular targets that may promote the clinical application of exosomes.

Background:Prevention of diabetic heart myocardial ischemia-reperfusion (IR) injury (MIRI) is challenging. Propofol attenuates MIRI through its reactive oxygen species scavenging property at high doses, while its use at high doses causes hemodynamic instability. Salvianolic acid A (SAA) is a potent antioxidant that confers protection against MIRI. Both propofol and SAA affect metabolic profiles through regulating Adenosine 5'-monophosphate-activated protein kinase (AMPK). The aim of this study was to investigate the protective effects and underlying mechanisms of low doses of propofol combined with SAA against diabetic MIRI. Methods:Diabetes was induced in mice by a high-fat diet followed by streptozotocin injection, and MIRI was induced by coronary artery occlusion and reperfusion. Mice were treated with propofol at 46 mg/kg/h without or with SAA at 10 mg/kg/h during IR. Cardiac origin H9c2 cells were exposed to high glucose (HG) and palmitic acid (PAL) for 24 h in the absence or presence of cluster of differentiation 36 (CD36) overexpression or AMPK gene knockdown, followed by hypoxia/reoxygenation (HR) for 6 and 12 h. Results:Diabetes-exacerbated MIRI is evidenced as significant increases in post-ischemic infarction with reductions in phosphorylated (p)-AMPK and increases in CD36 and ferroptosis. Propofol moderately yet significantly attenuated all the abovementioned changes, while propofol plus SAA conferred superior protection against MIRI to that of propofol. In vitro, exposure of H9c2 cells under HG and PAL decreased cell viability and increased oxidative stress that was concomitant with increased levels of ferroptosis and a significant increase in CD36, while p-AMPK was significantly reduced. Co-administration of low concentrations of propofol and SAA at 12.5 μM in H9c2 cells significantly reduced oxidative stress, ferroptosis and CD36 expression, while increasing p-AMPK compared to the effects of propofol at 25 μM. Moreover, either CD36 overexpression or AMPK silence significantly exacerbated HR-induced cellular injuries and ferroptosis, and canceled propofol- and SAA-mediated protection. Notably, p-AMPK expression was downregulated after CD36 overexpression, while AMPK knockdown did not affect CD36 expression. Conclusions:Combinational usage of propofol and SAA confers superior cellular protective effects to the use of high-dose propofol alone, and it does so through inhibiting HR-induced CD36 overexpression to upregulate p-AMPK.

The incidence of diabetes and related mortality rate increase yearly in modern cities. Additionally, elevated glucose levels can result in an increase of reactive oxygen species (ROS), ferroptosis, and the disruption of protective pathways in the heart. These factors collectively heighten the vulnerability of diabetic individuals to myocardial ischemia. Reperfusion therapies have been effectively used in clinical practice. There are limitations to the current clinical methods used to treat myocardial ischemia-reperfusion injury. As a result, reducing post-treatment ischemia/reperfusion injury remains a challenge. Therefore, efforts are underway to provide more efficient therapy. Salvia miltiorrhiza Bunge (Danshen) has been used for centuries in ancient China to treat cardiovascular diseases (CVD) with rare side effects. Salvianolic acid is a water-soluble phenolic compound with potent antioxidant properties and has the greatest hydrophilic property in Danshen. It has recently been discovered that salvianolic acids A (SAA) and B (SAB) are capable of inhibiting apoptosis by targeting the JNK/Akt pathway and the NF-κB pathway, respectively. This review delves into the most recent discoveries regarding the therapeutic and cardioprotective benefits of salvianolic acid for individuals with diabetes. Salvianolic acid shows great potential in myocardial protection in diabetes mellitus. A thorough understanding of the protective mechanism of salvianolic acid could expand its potential uses in developing medicines for treating diabetes mellitus related myocardial ischemia-reperfusion.

A large number of patients are affected by classical heart failure (HF) symptomatology with preserved ejection fraction (HFpEF) and multiorgan syndrome. Due to high morbidity and mortality rate, hospitalization and mortality remain serious socioeconomic problems, while the lack of effective pharmacological or device treatment means that HFpEF presents a major unmet medical need.Evidence from clinical and basic studies demonstrates that systemic inflammation, increased oxidative stress, and impaired mitochondrial function are the common pathological mechanisms in HFpEF. Tetrahydrobiopterin (BH4), beyond being an endogenous co-factor for catalyzing the conversion of some essential biomolecules, has the capacity to prevent systemic inflammation, enhance antioxidant resistance, and modulate mitochondrial energy production. Therefore, BH4 has emerged in the last decade as a promising agent to prevent or reverse the progression of disorders such as cardiovascular disease.In this review, we cover the clinical progress and limitations of using downstream targets of nitric oxide (NO) through NO donors, soluble guanylate cyclase activators, phosphodiesterase inhibitors, and sodium-glucose co-transporter 2 inhibitors in treating cardiovascular diseases, including HFpEF. We discuss the use of BH4 in association with HFpEF, providing new evidence for its potential use as a pharmacological option for treating HFpEF.

Background: Ischemic postconditioning (IPostC) has been reported as a promising method for protecting against myocardial ischemia-reperfusion (MI/R) injury. Our previous study found that the infarct-limiting effect of IPostC is abolished in the heart of diabetes whose cardiac expression of DJ-1 (also called PARK7, Parkinsonism associated deglycase) is reduced. However, the role and in particular the underlying mechanism of DJ-1 in the loss of sensitivity to IPostC-induced cardioprotection in diabetic hearts remains unclear. Methods: Streptozotocin-induced type 1 diabetic rats were subjected to MI/R injury by occluding the left anterior descending artery (LAD) and followed by reperfusion. IPostC was induced by three cycles of 10s of reperfusion and ischemia at the onset of reperfusion. AAV9-CMV-DJ-1, AAV9-CMV-C106S-DJ-1 or AAV9-DJ-1 siRNA were injected via tail vein to either over-express or knock-down DJ-1 three weeks before inducing MI/R. Results: Diabetic rats subjected to MI/R exhibited larger infarct area, more severe oxidative injury concomitant with significantly reduced cardiac DJ-1 expression and increased PTEN expression as compared to non-diabetic rats. AAV9-mediated cardiac DJ-1 overexpression, but not the cardiac overexpression of DJ-1 mutant C106S, restored IPostC-induced cardioprotection and this effect was accompanied by increased cytoplasmic DJ-1 translocation toward nuclear and mitochondrial, reduced PTEN expression, and increased Nrf-2/HO-1 transcription. Our further study showed that AAV9-mediated targeted DJ-1 gene knockdown aggravated MI/R injury in diabetic hearts, and this exacerbation of MI/R injury was partially reversed by IPostC in the presence of PTEN inhibition or Nrf-2 activation. Conclusions: These findings suggest that DJ-1 preserves the cardioprotective effect of IPostC against MI/R injury in diabetic rats through nuclear and mitochondrial DJ-1 translocation and that inhibition of cardiac PTEN and activation of Nrf-2/HO-1 may represent the major downstream mechanisms whereby DJ-1 preserves the cardioprotective effect of IPostC in diabetes.

Abstract ID 97790Poster Board 070Background: Myocardial infarction as a result of ischemic heart disease is the primary cause of death in patients with type 2 diabetes mellitus (T2DM). Reperfusion therapy restores blood flow, but paradoxically exacerbates myocardial injury, known as ischemia/reperfusion injury (I/RI). Ferroptosis is an important type of cardiomyocyte death caused by infarction-reperfusion, especially in the later phase of reperfusion.Research has shown that abnormal expression of the Angiopoietin-like protein 4(ANGPTL4) is associated with various pathological conditions, such as myocardial ischemia and diabetic cardiomyopathy. The role of ANGPTL4 in diabetic myocardial IRI and its potential interaction with myocardial cell ferroptosis in this pathology is unknown.Methods: Male C57BL/6 mice were fed with a high-fat diet (HFD) for 6 weeks and received intraperitoneal injection of low dose streptozotocin to induce T2DM. In vivo diabetic myocardial I/R model was induced by occluding the left anterior descending (LAD) artery for 30 mins, followed by 2h reperfusion. Sham operations were performed by passing a silk thread under the LAD without occlusion. Infarct size was determined by using Evans blue/TTC staining, and cardiac function was determined by echocardiography. In vitro, The cardiac origin HL-1 cells were exposed to high glucose (HG) and palmitic acid (PAL) for 24 hours, followed by H/R (6 hours hypoxia followed by 12 hours reoxygenation) in the absence or presence of ANGPTL4 gene knockdown or AMPK gene overexpression.Results: The result showed that ANGPTL4 increased significantly in the diabetic mouse myocardium after I/RI and in H/R-stimulated HL-1 cells, but cardiac levels of p-AMPK and p-AKT reduced as compared to non-diabetic control that was accompanied with reduced GPX4 protein expression and increased oxidative stress and ferroptosis. Knockdown of ANGPTL4 in HL-1 cells with ANGPTL4 siRNA significantly enhanced GPX4 protein expression, reduced ferroptosis as evidenced by reduced production of reactive substances, ferrous ion content and lipid peroxidation and attenuated H/R-induced cell injury that was concomitant enhanced protein levels of p-AMPK and p-AKT. Activation of Akt is known to protect against myocardial I/RI via inhibition of cell apoptosis, and activation of AMPK may be related to the inhibition of cell ferroptosis. Of note, overexpression of AMPK in HL-1 cells cultured under diabetic conditions with high glucose and palmitate reversed H/R induced reductions in p-Akt and GPX4, and significantly reduced post-hypoxic ferroptosis and cardiomyocyte injuries without significant impact on the increased post-hypoxic ANGPTL4 protein expression.Conclusion: Findings of the current study are indicative that excessive enhancement of ANGPTL4 after myocardial I/RI in diabetic conditions may exacerbate post-ischemic myocardial injury via impairing P-AMPK/P-AKT signaling and that AMPK works downstream of ANGPTL4.Funding: This study was supported by National Natural Science Foundation of China (NSFC, 81970427,82270306), and The Hong Kong Polytechnic University Translational Research Grant HK from Faculty of Health and Social Sciences (P0048507).

High-intensity interval training (HIIT) has been found to be more effective in relieving heart failure (HF) symptoms, than moderate-intensity continuous aerobic training (MICT). Additionally, higher meteorin-like protein (Metrnl) levels are seen after HIIT versus MICT. We investigated whether Metrnl contributed to post-HF cardiac functional improvements, and the signaling pathways involved. 50 HF patients underwent MICT, and another 50, HIIT, which was followed by cardiac function and serum Metrnl measurements. Metrnl was also measured in both blood and skeletal muscle samples of mice with transverse aortic constriction-induced HF after undergoing HIIT. Afterward, shRNA-containing adenovectors were injected into mice, yielding five groups: control, HF, HF + HIIT + scrambled shRNA, HF + HIIT + shMetrnl, and HF + Metrnl (HF + exogenous Metrnl). Mass spectrometry identified specific signaling pathways associated with increased Metrnl, which was confirmed with biochemical analyses. Glucose metabolism and mitochondrial functioning were evaluated in cardiomyocytes from the five groups. Both HF patients and mice had higher circulating Metrnl levels post-HIIT. Metrnl activated AMPK in cardiomyocytes, subsequently increasing histone deacetylase 4 (HDAC4) phosphorylation, leading to its cytosolic sequestration and inactivation via binding with chaperone protein 14-3-3. HDAC4 inactivation removed its repression on glucose transporter type 4, which, along with increased mitochondrial complex I-V expression, yielded improved aerobic glucose respiration and alleviation of mitochondrial dysfunction. All these changes ultimately result in improved post-HF cardiac functioning. HIIT increased skeletal muscle Metrnl production, which then operated on HF hearts to alleviate their functional defects, via increasing aerobic glucose metabolism through AMPK-HDAC4 signaling.