BACKGROUND:Mortality from acute myocardial infarction (MI) has declined significantly in the past decade for nondiabetic patients. However, both morbidity and mobility of ischemic heart failure (IHF) persistently escalate in the diabetic population via incompletely understood mechanisms. Recent studies demonstrated that small extracellular vesicles (sEVs) released from nondiabetic and diabetic adipocytes (ADps) exert opposite effects on acute myocardial ischemia and reperfusion (MI/R) injury. However, whether and how ADp sEVs may protect against post-MI remodeling and IHF, and more important, whether and how diabetes may impair this protective effect, remain unknown. METHODS:sEVs were isolated from epididymal fat pads of nondiabetic animals and intramyocardially injected in nondiabetic or diabetic hearts subjected to MI (90 minutes of MI per 4 weeks of reperfusion). RESULTS:sEV treatment significantly attenuated post-MI cardiac remodeling and improved cardiac function in nondiabetic mice. However, the protection was not observed in diabetic hearts. In adult cardiomyocytes isolated from nondiabetic hearts, sEVs rapidly (15 minutes) activated cell salvage kinases (ERK [extracellular signal-regulated kinase], AMPK [AMP-activated protein kinase], and ACC [acetyl-CoA carboxylase]) and suppressed oxidative stress-induced cell death, suggesting sEV external surface molecules are responsible for the observed cytoprotection. The Exo-Flow (a technology detecting sEV external surface molecules) demonstrated that adiponectin (APN) is enriched on the sEV external surface. The sEVs from APN knockout mice or APN neutralization (NU) antibody pretreated sEVs failed to protect the heart against IHF. Moreover, the cardioprotective effects of sEVs were abolished in APN receptor-1 (AdipoR1)-deficient mice (the primary receptor for APN signaling in the heart) or in mice overexpressing GRK2 (G-protein-coupled receptor kinase 2, a kinase that phosphorylates and inactivates AdipoR1). Finally, diabetes significantly increased cardiac GRK2 expression and AdipoR1 phosphorylation, which prevented sEVs from exerting their beneficial effects. Restoring AdipoR1 function by knockin a mutated phosphorylation-resistant AdipoR1 (AdipoR1S205A) via AAV9 (adeno-associated virus 9)-mediated gene delivery rescued ADp sEV cardioprotection in diabetic mice. CONCLUSIONS:Our study reveals that APN is enriched on the ADp-derived external surface of sEVs and is biologically active, playing a critical role in ADp-cardiomyocyte communication. Diabetes disrupts this communication by enhancing GRK2-mediated AdipoR1 phosphorylation, impairing sEV signaling, and exacerbating IHF. These findings provide new insights into the pathophysiology and therapy of IHF in diabetes.

Background: Diabetes increases ischemic heart injury via incompletely understood mechanisms. We recently reported that diabetic adipocytes-derived small extracellular vesicles (sEV) exacerbate myocardial reperfusion (MI/R) injury by promoting cardiomyocyte apoptosis. Combining in vitro mechanistic investigation and in vivo proof-concept demonstration, we determined the underlying molecular mechanism responsible for diabetic sEV-induced cardiomyocyte apoptosis after MI/R. Methods and results: Adult mice were fed a high-fat diet (HFD) for 12 weeks. sEV were isolated from plasma or epididymal adipose tissue. HFD significantly increased the number and size of plasma- and adipocyte-derived sEV. Intramyocardial injection of an equal number of diabetic plasma sEV in nondiabetic hearts significantly increased cardiac apoptosis and exacerbated MI/R-induced cardiac dysfunction. Diabetic plasma sEV significantly activated cardiac caspase 9 but not caspase 8, suggesting that diabetic sEV induces cardiac apoptosis via the mitochondrial pathway. These pathologic alterations were phenotyped by intramyocardial injection of sEV isolated from diabetic adipocytes or HGHL-challenged 3T3L1 adipocytes. To obtain direct evidence that diabetic sEV promotes cardiomyocyte apoptotic cell death, isolated neonatal rat ventricular cardiomyocytes (NRVMs) were treated with sEV and subjected to simulated ischemia/reperfusion (SI/R). Treatment of cardiomyocytes with sEV from diabetic plasma, diabetic adipocytes, or HGHL-challenged 3T3L1 adipocytes significantly enhanced SI/R-induced apoptosis and reduced cell viability. These pathologic effects were replicated by a miR-130b-3p (a molecule increased dramatically in diabetic sEV) mimic and blocked by a miRb-130b-3p inhibitor. Molecular studies identified PGC-1α (i.e. PGC-1α1/-a) as the direct downstream target of miR-130b-3p, whose downregulation causes mitochondrial dysfunction and apoptosis. Finally, treatment with diabetic adipocyte-derived sEV or a miR-130b-3p mimic significantly enhanced mitochondrial reactive oxygen species (ROS) production in SI/R cardiomyocytes. Conversely, treatment with a miR-130b-3p inhibitor or overexpression of PGC-1α extremely attenuated diabetic sEV-induced ROS production. Conclusion: We obtained the first evidence that diabetic sEV promotes oxidative stress and mitochondrial-mediated cardiomyocyte apoptotic cell death, exacerbating MI/R injury. These pathological phenotypes were mediated by miR-130b-3p-induced suppression of PGC-1α expression and subsequent mitochondrial ROS production. Targeting miR-130b-3p mediated cardiomyocyte apoptosis may be a novel strategy for attenuating diabetic exacerbation of MI/R injury.

Antiracism education (ARE) is critical in developing culturally competent physicians. At our institution, the Sidney Kimmel Medical College (SKMC) at Thomas Jefferson University in Philadelphia, United States, the Office of Diversity and Inclusion Initiatives and Educational Leadership created and examined a map of its ARE curriculum. Our efforts were meant to describe our local educational processes with regards to ARE; we did not intend to compare our curriculum and its outputs to national benchmarks. To this effect, diversity deans of other local Philadelphia -area medical schools were queried on their respective ARE maps and educational offerings. Potential changes to SKMC's ARE would be considered, but no other school that was queried had a formal ARE map in place. While all schools had a variety of lectures, modules, and electives, none appeared to have a systematic method to teach ARE. As a result, modifications to SKMC's ARE were made based on an intrinsic examination of its own ARE map. Changes that were made included modifying a pre -clerkship lecture on "Racism and Microaggressions" to a small group discussion session. Additionally, a clerkship -specific lecture on "Bias and Microaggressions" was changed from four 1 -hour lectures to 90 minutes of lecture followed by a 2 -hour small group session, to reduce content redundancy and promote more student reflection. For both of these changes, faculty participated in a newly developed faculty development session. To guide prospective work, a multidisciplinary task force was created to include formal student input in the process of examining ARE. Future directions to query institutions outside the Philadelphia region for their ARE offerings will also be considered.

Background: Type 2 diabetes mellitus (DM) significantly exacerbates ischemic heart failure (IHF) by incompletely understood mechanisms. We recently reported that DM switches adipocyte-derived exosome (Exo) from cardioprotective signaling activators in nondiabetes (ND) to vehicles carrying cytotoxic molecules from DM adipocyte to heart. However, it remains unclear how DM triggers this switch and whether blocking it can protect against DM exacerbation of IHF. Methods and Results: ND or DM (12 weeks of high-fat diet) mice were subjected to MI/R (90 minutes/4 weeks) and treated with Exo (isolated from ND epidydimal fat pads and intramyocardially injected immediately before reperfusion). Exo administration significantly attenuated IHF in ND but not in DM mice. In vitro mechanistic and in vivo concept-prove experiments were conducted to determine how Exo protects against IHF and how DM blocks this protection. In cardiomyocytes (CM) from ND mice, Exo rapidly activated multiple injury salvage kinases (ISKs, including ERK, AMPK, and ACC) and attenuated cell death, suggesting that Exo-surface molecules mediate Exo cardioprotection. Exo-Flow (a method specifically detects Exo surface molecules) experiments demonstrated that adipocyte-derived Exo carries high levels of adiponectin (APN) on their surface. APN antibody-neutralized Exo or APNKO mice-derived Exo neither activated ISKs nor attenuated IHF. Exo failed to activate ISKs and protect IHF in AdipoR1KO mice. These results demonstrated that the adipocyte Exo surface-localized APN and CM-expressed AdipoR1 are essential in protective communication between adipocyte and heart. GRK2, a kinase that phosphorylates AdipoR1 at S205 and blocks APN cardioprotection, was dramatically upregulated in DM hearts. GRK2 overexpression blocked Exo-induced ISKs activation and cellular protection in WT CM but not in AdipoR1 S205A knock-in CM. Finally, Exo administration in AAV9-mediated CM-specific AdipoR1 S205A knock-in mice significantly attenuated diabetic IHF, while it failed to protect in AdipoR1 S205E mice. Conclusions: This study sheds light on the mechanisms underlying DM exacerbation of IHF and highlights the potential of targeting the APN/AdipoR1/GRK2 axis to protect against this condition.

Diabetes worsen myocardial ischemic/reperfusion (MI/R) injury, but the underlying mechanism is still not fully understood. Epigenetics regulation is markedly involved in the process. Adiponectin (APN), a cardioprotective adipokine, is suppressed by diabetes, and dysregulated miRNAs are implicated in disease development. However, it is unclear whether hypoadiponectinemia alters cardiac miRNA profile, contributing to diabetic heart injury. Wild-type (WT) and APN knockout (APN-KO) mice were subjected to MI/R and cardiac microRNA profile were determined. Comparing those miRNAs that increased in APN-KO mice following MI/R, miR-449b was most significantly upregulated (3.98-fold over WT mice). Administering miR-449b mimic increased apoptosis, enlarged infarct size, and impaired cardiac function in WT mice. In contrast, anti-miR-449b decreased apoptosis, reduced infarct size, and improved cardiac function in APN-KO mice. In depth Bioinformatic analysis revealed oxidative stress as the top pathway regulated by miR449b. Venn analysis followed by luciferase assay identified Nrf-1 and Ucp3 as the two most important miR-449b targets. Administrating anti-miR-449b to APN-KO mice attenuated MI/R-stimulated superoxide overproduction. High glucose/high lipid in vitro treatment simulated ischemia/reperfusion upregulated miR-449b, leading to inhibition of Nrf-1 and Ucp3. These pathological effects were attenuated by anti-miR-449b or Nrf-1 overexpression. Clinically relevant cohorh study in high-fat diet (HFD)-induced diabetic mice followed with MI/R identified the copied pheonotype. Administration of anti-miR-449b or APN preserved cardiac Nrf-1 expression, reduced cardiac oxidative stress, decreased apoptosis and infarct size, and improved cardiac function. In conclusion, the study shows that hypoadiponectinemia upregulates miR-449b, suppressing Nrf-1/Ucp3 expression, which leads to oxidative stress and worsens MI/R injury. The APN/miR-449b/oxidative stress pathway could potentially be a therapeutic target for diabetic MI/R injury.

BACKGROUND: APN (adiponectin) and APPL1 (adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1) are potent vasculoprotective molecules, and their deficiency (eg, hypoadiponectinemia) contributes to diabetic vascular complications. However, the molecular mechanisms that govern their vasculoprotective genes as well as their alteration by diabetes remain unknown. METHODS: Diabetic medium-cultured rat aortic endothelial cells, mouse aortic endothelial cells from high-fat-diet animals, and diabetic human aortic endothelial cells were used for molecular/cellular investigations. The in vivo concept-prove demonstration was conducted using diabetic vascular injury and diabetic hindlimb ischemia models. RESULTS: In vivo animal experiments showed that APN replenishment caused APPL1 nuclear translocation, resulting in an interaction with HDAC (histone deacetylase) 2, which inhibited HDAC2 activity and increased H3Kac27 levels. Based on transcriptionome pathway-specific real-time polymerase chain reaction profiling and bioinformatics analysis, Angpt1 (angiopoietin 1), Ocln (occludin), and Cav1 (caveolin 1) were found to be the top 3 vasculoprotective genes suppressed by diabetes and rescued by APN in an APPL1-dependent manner. APN reverses diabetes-induced inhibition of Cav1 interaction with APPL1. APN-induced Cav1 expression was not affected by Angpt1 or Ocln deficiency, whereas APN-induced APPL1 nuclear translocation or upregulation of Angpt1/Ocln expression was abolished in the absence of Cav1 both in vivo and in vitro, suggesting Cav1 is upstream molecule of Angpt1/Ocln in response to APN administration. Chromatin immunoprecipitation–qPCR (quantitative polymerase chain reaction) demonstrated that APN caused significant enrichment of H3K27ac in Angpt1 and Ocln promoter region, an effect blocked by APPL1/Cav1 knockdown or HDAC2 overexpression. The protective effects of APN on the vascular system were attenuated by overexpression of HDAC2 and abolished by knocking out APPL1 or Cav1. The double knockdown of ANGPT1/OCLN blunted APN vascular protection both in vitro and in vivo. Furthermore, in diabetic human endothelial cells, HDAC2 activity is increased, H3 acetylation is decreased, and ANGPT1/OCLN expression is reduced, suggesting that the findings have important translational implications. CONCLUSIONS: Hypoadiponectinemia and dysregulation of APPL1-mediated epigenetic regulation are novel mechanisms leading to diabetes-induced suppression of vasculoprotective gene expression. Diabetes-induced pathological vascular remodeling may be prevented by interventions promoting APPL1 nuclear translocation and inhibiting HDAC2.

Abstract Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and SARS-CoV-2 variants, has become a global pandemic resulting in significant morbidity and mortality. Severe cases of COVID-19 are characterized by hypoxemia, hyperinflammation, cytokine storm in lung. Clinical studies have reported an association between COVID-19 and cardiovascular disease (CVD). Patients with CVD tend to develop severe symptoms and mortality if contracted COVID-19 with further elevations of cardiac injury biomarkers. Furthermore, COVID-19 itself can induce and promoted CVD development, including myocarditis, arrhythmia, acute coronary syndrome, cardiogenic shock, and venous thromboembolism. Although the direct etiology of SARS-CoV-2–induced cardiac injury remains unknown and underinvestigated, it is suspected that it is related to myocarditis, cytokine-mediated injury, microvascular injury, and stress-related cardiomyopathy. Despite vaccinations having provided the most effective approach to reducing mortality overall, an adapted treatment paradigm and regular monitoring of cardiac injury biomarkers is critical for improving outcomes in vulnerable populations at risk for severe COVID-19. In this review, we focus on the latest progress in clinic and research on the cardiovascular complications of COVID-19 and provide a perspective of treating cardiac complications deriving from COVID-19 in emergency medicine.

Background: Myocardial insulin resistance is a hallmark of diabetic cardiac injury. However, the underlying molecular mechanisms remain unclear. Recent studies demonstrate that the diabetic heart is resistant to other cardioprotective interventions, including adiponectin and preconditioning. The “universal” resistance to multiple therapeutic interventions suggests impairment of the requisite molecule(s) involved in broad prosurvival signaling cascades. Cav (Caveolin) is a scaffolding protein coordinating transmembrane signaling transduction. However, the role of Cav3 in diabetic impairment of cardiac protective signaling and diabetic ischemic heart failure is unknown. Methods: Wild-type and gene-manipulated mice were fed a normal diet or high-fat diet for 2 to 12 weeks and subjected to myocardial ischemia and reperfusion. Insulin cardioprotection was determined. Results: Compared with the normal diet group, the cardioprotective effect of insulin was significantly blunted as early as 4 weeks of high-fat diet feeding (prediabetes), a time point where expression levels of insulin-signaling molecules remained unchanged. However, Cav3/insulin receptor-β complex formation was significantly reduced. Among multiple posttranslational modifications altering protein/protein interaction, Cav3 (not insulin receptor-β) tyrosine nitration is prominent in the prediabetic heart. Treatment of cardiomyocytes with 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride reduced the signalsome complex and blocked insulin transmembrane signaling. Mass spectrometry identified Tyr 73 as the Cav3 nitration site. Phenylalanine substitution of Tyr 73 (Cav3 Y73F ) abolished 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride–induced Cav3 nitration, restored Cav3/insulin receptor-β complex, and rescued insulin transmembrane signaling. It is most important that adeno-associated virus 9–mediated cardiomyocyte-specific Cav3 Y73F reexpression blocked high-fat diet–induced Cav3 nitration, preserved Cav3 signalsome integrity, restored transmembrane signaling, and rescued insulin-protective action against ischemic heart failure. Last, diabetic nitrative modification of Cav3 at Tyr 73 also reduced Cav3/AdipoR1 complex formation and blocked adiponectin cardioprotective signaling. Conclusions: Nitration of Cav3 at Tyr 73 and resultant signal complex dissociation results in cardiac insulin/adiponectin resistance in the prediabetic heart, contributing to ischemic heart failure progression. Early interventions preserving Cav3-centered signalsome integrity is an effective novel strategy against diabetic exacerbation of ischemic heart failure.

Diabetes enhances myocardial ischemic/reperfusion (MI/R) injury via an incompletely understood mechanism. Adiponectin (APN) is a cardioprotective adipokine suppressed by diabetes. However, how hypoadiponectinemia exacerbates cardiac injury remains incompletely understood. Dysregulation of miRNAs plays a significant role in disease development. However, whether hypoadiponectinemia alters cardiac miRNA profile, contributing to diabetic heart injury, remains unclear. Methods and Results: Wild-type (WT) and APN knockout (APN-KO) mice were subjected to MI/R. A cardiac microRNA profile was determined. Among 23 miRNAs increased in APN-KO mice following MI/R, miR-449b was most significantly upregulated (3.98-fold over WT mice). Administrating miR-449b mimic increased apoptosis, enlarged infarct size, and impaired cardiac function in WT mice. In contrast, anti-miR-449b decreased apoptosis, reduced infarct size, and improved cardiac function in APN-KO mice. Bioinformatic analysis predicted 73 miR-449b targeting genes, and GO analysis revealed oxidative stress as the top pathway regulated by these genes. Venn analysis followed by luciferase assay identified Nrf-1 and Ucp3 as the two most important miR-449b targets. In vivo administration of anti-miR-449b in APN-KO mice attenuated MI/R-stimulated superoxide overproduction. In vitro experiments demonstrated that high glucose/high lipid and simulated ischemia/reperfusion upregulated miR-449b and inhibited Nrf-1 and Ucp3 expression. These pathological effects were attenuated by anti-miR-449b or Nrf-1 overexpression. In a final attempt to validate our finding in a clinically relevant model, high-fat diet (HFD)-induced diabetic mice were subjected to MI/R and treated with anti-miR-449b or APN. Diabetes significantly increased miR-449b expression and downregulated Nrf-1 and Ucp3 expression. Administration of anti-miR-449b or APN preserved cardiac Nrf-1 expression, reduced cardiac oxidative stress, decreased apoptosis and infarct size, and improved cardiac function. Conclusion: We demonstrated for the first time that hypoadiponectinemia upregulates miR-449b and suppresses Nrf-1/Ucp3 expression, promoting oxidative stress and exacerbating MI/R injury in this population. Dysregulated APN/miR-449b/oxidative stress pathway is a potential therapeutic target against diabetic MI/R injury.

Homologous recombination (HR) is a DNA repair mechanism of double-strand breaks and blocked replication forks, involving a process of homology search leading to the formation of synaptic intermediates that are regulated to ensure genome integrity. RAD51 recombinase plays a central role in this mechanism, supported by its RAD52 and BRCA2 partners. If the mediator function of BRCA2 to load RAD51 on RPA-ssDNA is well established, the role of RAD52 in HR is still far from understood. We used transmission electron microscopy combined with biochemistry to characterize the sequential participation of RPA, RAD52, and BRCA2 in the assembly of the RAD51 filament and its activity. Although our results confirm that RAD52 lacks a mediator activity, RAD52 can tightly bind to RPA-coated ssDNA, inhibit the mediator activity of BRCA2, and form shorter RAD51-RAD52 mixed filaments that are more efficient in the formation of synaptic complexes and D-loops, resulting in more frequent multi-invasions as well. We confirm the in situ interaction between RAD51 and RAD52 after double-strand break induction in vivo. This study provides new molecular insights into the formation and regulation of presynaptic and synaptic intermediates by BRCA2 and RAD52 during human HR.

BACKGROUND:Disparities in salary and advancement of emergency medicine (EM) faculty by race and gender have been consistently demonstrated for over three decades. Prior studies have largely focused on individual-level solutions. To identify systems-based interventions, the Society for Academic Emergency Medicine (SAEM) formed the Research Equity Task Force in 2018 with members from multiple academies (the Academy of Academic Chairs in Emergency Medicine [AACEM], the Academy of Academic Administrators in Emergency Medicine [AAAEM], the Academy for Women in Academic Emergency Medicine [AWAEM], and the Academy for Diversity and Inclusion in Emergency Medicine [ADIEM]) and sought recommendations from EM departmental leaders.METHODS:The task force conducted interviews containing both open-ended narrative and closed-ended questions in multiple phases. Phase 1 included a convenience sample of chairs of EM departments across the United States, and phase 2 included vice-chairs and other faculty who lead promotion and advancement. The task force identified common themes from the interviews and then developed three-tiered sets of recommendations (minimal, target, and aspirational) based on participant responses. In phase 3, iterative feedback was collected and implemented on these recommendations from study participants and chairs participating in a national AACEM webinar.RESULTS:In findings from 53 interviews of chairs, vice-chairs, and faculty leaders from across the United States, we noted heterogeneity in the faculty development and promotion processes across institutions. Four main themes were identified from the interviews: the need for a directed, structured promotion process; provision of structured mentorship; clarity on requirements for promotion within tracks; and transparency in salary structure. Recommendations were developed to address gaps in structured mentorship and equitable promotion and compensation.CONCLUSIONS:These recommendations for AEM departments have the potential to increase structured mentorship programs, improve equity in promotion and advancement, and reduce disparities in the AEM workforce. These recommendations have been endorsed by SAEM, AACEM, AWAEM, ADIEM, and AAAEM.

BACKGROUND:Despite significantly reduced acute myocardial infarction (MI) mortality in recent years, ischemic heart failure continues to escalate. Therapeutic interventions effectively reversing pathological remodeling are an urgent unmet medical need. We recently demonstrated that AdipoR1 (APN [adiponectin] receptor 1) phosphorylation by GRK2 (G-protein-coupled receptor kinase 2) contributes to maladaptive remodeling in the ischemic heart. The current study clarified the underlying mechanisms leading to AdipoR1 phosphorylative desensitization and investigated whether blocking AdipoR1 phosphorylation may restore its protective signaling, reversing post-MI remodeling. METHODS:Specific sites and underlying molecular mechanisms responsible for AdipoR1 phosphorylative desensitization were investigated in vitro (neonatal and adult cardiomyocytes). The effects of AdipoR1 phosphorylation inhibition upon APN post-MI remodeling and heart failure progression were investigated in vivo. RESULTS:Among 4 previously identified sites sensitive to GRK2 phosphorylation, alanine substitution of Ser205 (AdipoR1S205A), but not other 3 sites, rescued GRK2-suppressed AdipoR1 functions, restoring APN-induced cell salvage kinase activation and reducing oxidative cell death. The molecular investigation followed by functional determination demonstrated that AdipoR1 phosphorylation promoted clathrin-dependent (not caveolae) endocytosis and lysosomal-mediated (not proteasome) degradation, reducing AdipoR1 protein level and suppressing AdipoR1-mediated cytoprotective action. GRK2-induced AdipoR1 endocytosis and degradation were blocked by AdipoR1S205A overexpression. Moreover, AdipoR1S205E (pseudophosphorylation) phenocopied GRK2 effects, promoted AdipoR1 endocytosis and degradation, and inhibited AdipoR1 biological function. Most importantly, AdipoR1 function was preserved during heart failure development in AdipoR1-KO (AdipoR1 knockout) mice reexpressing hAdipoR1S205A. APN administration in the failing heart reversed post-MI remodeling and improved cardiac function. However, reexpressing hAdipoR1WT in AdipoR1-KO mice failed to restore APN cardioprotection. CONCLUSIONS:Ser205 is responsible for AdipoR1 phosphorylative desensitization in the failing heart. Blockade of AdipoR1 phosphorylation followed by pharmacological APN administration is a novel therapy effective in reversing post-MI remodeling and mitigating heart failure progression.

BACKGROUND:Patients with acute myocardial infarction suffer systemic metabolic dysfunction via incompletely understood mechanisms. Adipocytes play critical role in metabolic homeostasis. The impact of acute myocardial infarction upon adipocyte function is unclear. Small extracellular vesicles (sEVs) critically contribute to organ-organ communication. Whether and how small extracellular vesicle mediate post-MI cardiomyocyte/adipocyte communication remain unknown.METHODS:Plasma sEVs were isolated from sham control (Pla-sEVSham) or 3 hours after myocardial ischemia/reperfusion (Pla-sEVMI/R) and incubated with adipocytes for 24 hours. Compared with Pla-sEVSham, Pla-sEVMI/R significantly altered expression of genes known to be important in adipocyte function, including a well-known metabolic regulatory/cardioprotective adipokine, APN (adiponectin). Pla-sEVMI/R activated 2 (PERK-CHOP and ATF6 [transcription factor 6]-EDEM [ER degradation enhancing alpha-mannosidase like protein 1] pathways) of the 3 endoplasmic reticulum (ER) stress pathways in adipocytes. These pathological alterations were also observed in adipocytes treated with sEVs isolated from adult cardiomyocytes subjected to in vivo myocardial ischemia/reperfusion (MI/R) (Myo-sEVMI/R). Bioinformatic/RT-qPCR analysis demonstrates that the members of miR-23-27-24 cluster are significantly increased in Pla-sEVMI/R, Myo-sEVMI/R, and adipose tissue of MI/R animals. Administration of cardiomyocyte-specific miR-23-27-24 sponges abolished adipocyte miR-23-27-24 elevation in MI/R animals, supporting the cardiomyocyte origin of adipocyte miR-23-27-24 cluster. In similar fashion to Myo-sEVMI/R, a miR-27a mimic activated PERK-CHOP and ATF6-EDEM-mediated ER stress. Conversely, a miR-27a inhibitor significantly attenuated Myo-sEVMI/R-induced ER stress and restored APN production.RESULTS:An unbiased approach identified EDEM3 (ER degradation enhancing alpha-mannosidase like protein 3) as a novel downstream target of miR-27a. Adipocyte EDEM3 deficiency phenocopied multiple pathological alterations caused by Myo-sEVMI/R, whereas EDEM3 overexpression attenuated Myo-sEVMI/R-resulted ER stress. Finally, administration of GW4869 or cardiomyocyte-specific miR-23-27-24 cluster sponges attenuated adipocyte ER stress, improved adipocyte endocrine function, and restored plasma APN levels in MI/R animals.CONCLUSIONS:We demonstrate for the first time that MI/R causes significant adipocyte ER stress and endocrine dysfunction by releasing miR-23-27-24 cluster-enriched small extracellular vesicle. Targeting small extracellular vesicle-mediated cardiomyocyte-adipocyte pathological communication may be of therapeutic potential to prevent metabolic dysfunction after MI/R.

Introduction: Myocardial insulin resistant is a hallmark of diabetic cardiac injury. However, underlying molecular mechanisms remain unclear. Recent studies show that diabetic heart is resistant to other cardioprotective interventions, including adiponectin and pre-conditioning. The “universal” resistance to multiple therapeutic interventions suggests impairment of the requisite molecule(s) involved in broad pro-survival signaling cascades. Caveolin (Cav) is a scaffolding protein coordinating transmembrane signaling transduction. However, role of Cav3 in diabetic impairment of cardiac protective signaling and diabetic ischemic heart failure (HF) is unknown. Methods and Results: Mice were fed normal diet (ND) or high-fat-diet (HFD) and subjected to myocardial ischemia and reperfusion. The cardioprotective effect of insulin was significantly blunted as early as 4 weeks of HFD feeding (pre-diabetes), when insulin signals remain unchanged. However, Cav3/IRβ complex formation, requisite for insulin transmembrane signaling, was significantly reduced. Among multiple post-translational modifications altering proteins interaction, Cav3 (not IRβ or AdipoR1) tyrosine nitration is prominent in the pre-diabetic heart. SIN-1 treatment reduced the signalsome formation and blocked insulin transmembrane signaling. Mass spectrometry identified Tyr 73 is the Cav3 nitration site. Phenylalanine substitution of Tyr 73 (Cav3 Y73F ) abolished SIN-1 induced Cav3 nitration, restored Cav3/IRβ complex, and rescued insulin transmembrane signaling. AAV9-mediated cardiac Cav3 Y73F re-expression blocked HFD-induced Cav3 nitration, preserved Cav3 signalsome integrity, and rescued insulin protective action against ischemic HF. Finally, diabetic nitrative modification of Cav3 at Tyr 73 also reduced Cav3/AdipoR1 complex formation and blocked adiponectin cardioprotective signaling. Conclusion: Nitration of Cav3 at Tyr 73 and resultant signal complex dissociation is responsible for cardiac insulin/adiponectin resistance in the pre-diabetic heart, contributing to ischemic HF progression. Early interventions preserving Cav3-centered signalsome integrity is an effective novel strategy against diabetic exacerbation of ischemic HF.

Background The impairment of the inner blood–retinal barrier (iBRB) increases the pathological development of diabetic retinopathy (DR), a severe complication in diabetic patients. Identifying approaches to preserving iBRB integrity and function is a significant challenge in DR. C1q/tumor necrosis factor-related protein-3 (CTRP3) is a newly discovered adipokine and a vital biomarker, predicting DR severity. We sought to determine whether and how CTRP3 affects the pathological development of non-proliferative diabetic retinopathy (NPDR). Methods To clarify the pathophysiologic progress of the blood–retinal barrier in NPDR and explore its potential mechanism, a mouse Type 2 diabetic model of diabetic retinopathy was used. The capillary leakage was assessed by confocal microscope with fluorescent-labeled protein in vivo. Furthermore, the effect of CTRP3 on the inner blood–retinal barrier (iBRB) and its molecular mechanism was clarified. Results The results demonstrated that CTRP3 protects iBRB integrity and resists the vascular permeability induced by DR. Mechanistically, the administration of CTRP3 activates the AMPK signaling pathway and enhances the expression of Occludin and Claudin-5 (tight junction protein) in vivo and in vitro. Meanwhile, CTRP3 improves the injury of human retinal endothelial cells (HRMECs) induced by high glucose/high lipids (HG/HL), and its protective effects are AMPK-dependent. Conclusions In summary, we report, for the first time, that CTRP3 prevents diabetes-induced retinal vascular permeability via stabilizing the tight junctions of the iBRB and through the AMPK-dependent Occludin/Claudin-5 signaling pathway, thus critically affecting the development of NPDR.

There is a paradox of nicotine and diabetes in patients with cardiomyopathy. Although great progress has been made in understanding the pathogenesis, it is urgent to clarify the in‐depth mechanism and identify new therapeutic targets for preventing diabetic cardiomyopathy (DCM) in smoker.

Background: Despite significant reduction in acute MI death, ischemic heart failure (IHF) and resultant death continually escalate with incompletely understood mechanism. We recently reported that adipocyte-derived exosomes (ADp-Exo) protect heart from acute MI/R injury. However, it remains unknown whether and how cardiomyocytes (CM) response to ADp-Exo is altered during the chronic phase of MI, negatively impacting IHF development. Methods and Results: Intramyocardial injection of ADp-Exo (isolated from epididymal fat pad) immediately after MI (90 min MI/4 weeks reperfusion) significantly attenuated post-MI remodeling. However, the protective effects were completely lost when ADp-Exo were administered 1 week after MI. To identify the molecular mechanisms responsible for ADp-Exo cardioprotection and its alteration during chronic MI, a series of in vitro experiments were performed. Adiponectin (APN), a potent cardioprotective adipokine, was detected on the surface of ADp-Exo (Exo-flow kit). Treatment of CM with ADp-Exo activated multiple cell salvage kinases (e.g., ACC, ERK and AMPK). These effects were lost in APN neutralization antibody pre-incubated ADp-Exo or ADp-Exo from APNKO mice, suggesting Exo surface APN may mediate ADp-Exo cardioprotection. Moreover, ADp-Exo cell salvage kinase activation effect was absent in CM from AdipoR1KO mice or GRK2 transfected CM, suggesting GRK2-induced AdipoR1 phosphorylation at Ser 205 (as we demonstrated in Circulation, 2015 and Circ Res, 2022) is likely responsible for incapability of ADp-Exo protection during post-MI remodeling. To obtain direct evidence supporting this novel hypothesis, AdipoR1 S205A or AdipoR1 S205E (pseudo-phosphorylation) mice were generated. ADp-Exo cardioprotection was restored in AdipoR1 S205A mice, even when they were administered 1 week after MI. In contrast, ADp-Exo cardioprotection was lost in AdipoR1 S205E mice, even when they were administered immediately after MI. Conclusions: We demonstrate for the first time that, APN located on the surface of ADp-Exo acts as the critical executor of ADp-CM communication, mediating ADp-Exo cardioprotection. GRK2-induced CM AdipoR1 phosphorylation blocks ADp-Exo protective action, contributing to IHF progression.