Progression Of Diabetic Cardiomyopathy Research Articles

Exercise alleviates cardiac remodelling in diabetic cardiomyopathy via the miR-486a-5p-Mst1 pathway.

Objective(s):Physical exercise has emerged as an effective therapy to mitigate cardiac remodelling in diabetic cardiomyopathy (DCM). The results of our previous studies revealed mammalian sterile 20-like kinase 1 (Mst1) is a key regulator of the progression of DCM. However, the precise molecular mechanism of physical exercise-induced cardiac protection and its association with Mst1 inhibition remain unclear. Materials and Methods:Wildtype and Mst1 transgenic mice were challenged with streptozotocin (STZ) to induce experimental diabetes and were divided into sedentary and exercise groups. The DCM phenotype was evaluated by echocardiography, Masson’s trichrome staining, TUNEL and immunoblotting analyses. The exercise-regulated miRNAs targeting Mst1 were predicted by bioinformatic analysis and later confirmed by RT-qPCR, immunoblotting, and dual-luciferase reporter assays. In addition, cultured neonatal mouse cardiomyocytes were subjected to simulate diabetes to elucidate the underlying mechanisms. Results:Compared to the sedentary diabetic control, physical exercise inhibited Mst1 and alleviated cardiac remodelling in mice with DCM, as evidenced by decreases in the left ventricular end-systolic internal dimension (LVESD) and left ventricular end-diastolic internal dimension (LVEDD), increases in the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), attenuation of collagen deposition, and the suppression of apoptosis. Bioinformatic analysis and apoptosis assessments revealed exercise exerted protective effects against DCM through miR-486a-5p release. Moreover, luciferase reporter assays confirmed miR-486a-5p directly suppressed the expression of Mst1, thereby inhibiting the apoptosis of cardiomyocytes subjected to high glucose treatment. Conclusion:Physical exercise inhibits cardiac remodelling in DCM, and the mechanism is associated with miR-486a-5p release-induced Mst1 inhibition.

Combination of Dendrobium Mixture and Metformin Curbs the Development and Progression of Diabetic Cardiomyopathy by Targeting the lncRNA NEAT1

OBJECTIVES:This study aimed to explore the efficacy of combination treatment with dendrobium mixture and metformin (Met) in diabetic cardiomyopathy (DCM) and its effects on NEAT1 and the Nrf2 signaling pathway.METHODS:H9c2 cells were maintained in medium supplemented with either low (5.5 mmol/L) or high (50 mmol/L) glucose. Male Sprague-Dawley rats were fed a high-glucose diet and administered a single, low dose of streptozotocin (35 mg/kg) via intraperitoneal injection to induce the development of DM. After induction of DM, the rats were treated with dendrobium mixture (10 g/kg) and Met (0.18 g/kg) daily for 4 weeks. Next, quantitative reverse transcription (qRT)-PCR and western blotting were performed to evaluate the expression levels of target genes and proteins. Flow cytometry was performed to assess apoptosis, and hematoxylin and eosin staining was performed to evaluate the morphological changes in rat cardiac tissue.RESULTS:In patients with diabetes mellitus (DM) and myocardial cells and heart tissues from rats with high glucose-induced DM, NEAT1 was downregulated, and the expression levels of Nrf2 were decreased (p<0.01, p<0.001). The combination of dendrobium mixture and Met upregulated the expression of NEAT1 which upregulated Nrf2 by targeting miR-23a-3p, resulting in reduced apoptosis and improved cardiac tissue morphology (p<0.01, p<0.001).CONCLUSION:Dendrobium mixture and Met upregulated the expression of NEAT1 in DCM, thereby inhibiting apoptosis of myocardial cells.

The MEK inhibitor U0126 ameliorates diabetic cardiomyopathy by restricting XBP1's phosphorylation dependent SUMOylation.

Background: Chronic diabetes accelerates vascular dysfunction often resulting in cardiomyopathy but underlying mechanisms remain unclear. Recent studies have shown that the deregulated unfolded protein response (UPR) dependent on highly conserved IRE1α-spliced X-box- binding protein (XBP1s) and the resulting endoplasmic reticulum stress (ER-Stress) plays a crucial role in the occurrence and development of diabetic cardiomyopathy (DCM). In the present study, we determined whether targeting MAPK/ERK pathway using MEK inhibitor U0126 could ameliorate DCM by regulating IRE1α-XBP1s pathway.Method: Three groups of 8-week-old C57/BL6J mice were studied: one group received saline injection as control (n=8) and two groups were made diabetic by streptozotocin (STZ) (n=10 each). 18 weeks after STZ injection and stable hyperglycemia, one group had saline treatment while the second group was treated with U0126 (1mg/kg/day), 8 weeks later, all groups were sacrificed. Cardiac function/histopathological changes were determined by echocardiogram examination, Millar catheter system, hematoxylin-eosin staining and western blot analysis. H9C2 cardiomyocytes were employed for in vitro studies.Results: Echocardiographic, hemodynamic and histological data showed overt myocardial hypertrophy and worsened cardiac function in diabetic mice. Chronic diabetic milieu enhanced SUMOylation and impaired nuclear translocation of XBP1s. Intriguingly, U0126 treatment significantly ameliorated progression of DCM, and this protective effect was achieved through enriching XBP1s' nuclear accumulation. Mechanistically, U0126 inhibited XBP1s' phosphorylation on S348 and SUMOylation on K276 promoting XBP1s' nuclear translocation. Collectively, these results identify that MEK inhibition restores XBP1s-dependent UPR and protects against diabetes-induced cardiac remodeling.Conclusion: The current study identifies previously unknown function of MEK/ERK pathway in regulation of ER-stress in DCM. U0126 could be a therapeutic target for the treatment of DCM.

Sex-Specific Effects of Daily Tadalafil on Contraction Kinetics of the Diabetic Heart. The RECOGITO Randomized, Double-Blind, Placebo-Controlled Trial

Background: Cardiovascular disease is the leading cause of morbidity and mortality in type 2 diabetes (T2DM) patients. Cyclic GMP-phosphodiesterase type 5 (PDE5) inhibition was shown to counteract maladaptive cardiac changes triggered by diabetes in some studies. Our aim was to assess sex differences in cardiac remodeling after PDE5 inhibition in patients with diabetic cardiomyopathy (DCM). Methods: We performed a 20-week, double-blind, randomized, placebo-controlled trial. Men and women (45–80 years) with controlled T2DM and echocardiographic (ECG) signs of cardiac remodeling were randomly assigned (1:1) to placebo or tadalafil 20 mg once daily. The primary outcome was analyzing the sex-difference in cardiac torsion change, from baseline to 20 weeks. Secondary outcomes included changes in cardiovascular, metabolic, immune and renal function. Efficacy analyses included all patients who received at least one dose of treatment. Findings: Between May 2014 and July 2018, we screened 220 diabetic subjects; 122 met the inclusion criteria and were randomized to tadalafil (n=61) or placebo (n=61). At 20 weeks, the sex-by-treatment interaction documented an improvement in cardiac torsion [-3·40°(-5·96;-0·84, p =0·011)], paralleled by a consensual increase in fiber shortening, in men but not women. Biomarkers of cardiovascular remodeling , titin and hsa-miR-199-5p, improved accordingly. In both sexes, tadalafil reduced TGF-beta and improved albuminuria, renal artery’s resistive index, Klotho , and symmetric-di-methyl-arginine markers . Five months of 20 mg daily tadalafil in patients with DCM was proven safe. The most common adverse reactions were myalgia (9[14·5%]), gastric reflux (6[9·7%]), headache (4[6·4%]) and flushing (2[3·8%]); one SAE occurred in the placebo arm. Interpretation: Continuous PDE5 inhibition could represent a new treatment strategy to target cardiac and renal complications of T2DM, with a different tissue-specific response in men and women. Klotho and hsa-miR-199-5p appear as novel players linking renal disease to DCM progression. Trial Registration: NCT01803828. Funding Statement: Italian Ministry of University and Research, SIR RBSI141LY2. Declaration of Interests: Prof. Isidori reports personal fees from Takeda; non-financial support from Takeda and Ipsen; and grants from Shire and Pfizer outside the submitted work; Prof. Pozzilli reports research contracts and consulting from Eli Lilly, Sanofi, Merck, Merck Sharpt Dohme, Astra Zeneca, Medtronic, Abbott; Dr. Defeudis reports grants from Ibsa, personal fees from Abbott, grants from Novo Nordisk, grants from Kyowa Kirin , personal fees from Roche, outside the submitted work; Prof. Badagliacca reports personal fees from Bayer, personal fees from MSD, personal fees from Dompe, personal fees from GSK, personal fees from Ferrer, personal fees from United Therapeutics, personal fees from Galenica, personal fees from Janssen, outside the submitted work; all others have nothing to disclose. Ethics Approval Statement: The study was performed in the Policlinico Umberto I in Rome (Italy) and approved by the local ethical review board (3083/14), published on public registries (NCT01803828, EUDRACT 2014-000077-39), and conducted under the Declaration of Helsinki and good clinical practice.

Diabetic Cardiomiopathy Progression is Triggered by miR122-5p and Involves Extracellular Matrix: A 5-Year Prospective Study

ObjectivesThe purpose of this study was to follow the long-term progression of diabetic cardiomyopathy by combining cardiac magnetic resonance (CMR) and molecular analysis. BackgroundThe evolution of diabetic cardiomyopathy to heart failure affects patients’morbidity and mortality. CMR is the gold standard to assess cardiac remodeling, but there is a lack of markers linked to the mechanism of diabetic cardiomyopathy progression. MethodsFive-year longitudinal study on patients with type 2 diabetes mellitus (T2DM) enrolled in the CECSID (Cardiovascular Effects of Chronic Sildenafil in Men With Type 2 Diabetes) trial compared with nondiabetic age-matched controls. CMR with tagging together with metabolic and molecular assessments were performed at baseline and 5-year follow-up. ResultsA total of 79 men (age 64 ± 8 years) enrolled, comprising 59 men with T2DM compared with 20 nondiabetic age-matched controls. Longitudinal CMR with tagging showed an increase in ventricular mass (ΔLVMi = 13.47 ± 29.66 g/m2; p = 0.014) and a borderline increase in end-diastolic volume (ΔEDVi = 5.16 ± 14.71 ml/m2; p = 0.056) in men with T2DM. Cardiac strain worsened (Δσ = 1.52 ± 3.85%; p = 0.033) whereas torsion was unchanged (Δθ = 0.24 ± 4.04°; p = 0.737), revealing a loss of the adaptive equilibrium between strain and torsion. Contraction dynamics showed a decrease in the systolic time-to-peak (ΔTtP = −35.18 ± 28.81 ms; p < 0.001) and diastolic early recoil-rate (ΔRR = −20.01 ± 19.07 s-1; p < 0.001). The ejection fraction and metabolic parameters were unchanged. Circulating miR microarray revealed an up-regulation of miR122-5p. Network analysis predicted the matrix metalloproteinases (MMPs) MMP-16 and MMP-2 and their regulator (tissue inhibitors of metalloproteinases) as targets. In db/db mice we demonstrated that miR122-5p expression is associated with diabetic cardiomyopathy, that in the diabetic heart is overexpressed, and that, in vitro, it regulates MMP-2. Finally, we demonstrated that miR122-5p overexpression affects the extracellular matrix through MMP-2 modulation. ConclusionsWithin 5 years of diabetic cardiomyopathy onset, increasing cardiac hypertrophy is associated with progressive impairment in strain, depletion of the compensatory role of torsion, and changes in viscoelastic contraction dynamics. These changes are independent of glycemic control and paralleled by the up-regulation of specific microRNAs targeting the extracellular matrix. (Cardiovascular Effects of Chronic Sildenafil in Men With Type 2 Diabetes [CECSID]; NCT00692237)

Abstract 13045: Chronic Beta3-Adrenergic Receptor Antagonist Therapy Rescues Diabetic Cardiomyopathy in a Mouse Model With Type 2 Diabetes: Insights into Cellular Mechanism

Background: Diabetic cardiomyopathy (DCM) leads to progressive decline in cardiac function, increasing the risk for heart failure. There are no known effective prevention approaches or therapeutic strategies. Recent evidence in diabetes mellitus (DM) human and animal hearts suggests that the up-regulation of β 3 -adrenergic receptor (AR)-mediated inhibitory pathway may be responsible for the progression of DCM. However, its precise role is still being debated. We hypothesize that β 3 -AR antagonists (β 3 -ANT) may rescue the detrimental effects of β 3 -AR activation, improve cardiomyocyte function, and preserve normal β-AR regulation, leading to the regression of DCM. Methods: We compared LV myocyte function, [Ca 2+ ] i transient ([Ca 2+ ] iT ) at baseline and responses to β-AR simulation with isoproterenol (ISO,10 -8 M) in 3 groups wild-type female mice over 14 weeks (W):1) Type 2 DM ( T2 ) (n=9), 14 W fed high-fat diet (HFD), but after HFD for 4 W receiving streptozotocin (STZ, 40 mg/kg/day, i.p. 5 days); 2) T2/β 3 -ANT (n=7), T2 mice at 10 W received L-748,337, a selective β 3 -ANT (10 -7 M/kg/day, mini-pump) for 4 W; and 3) Vehicle controls (C) (n=9). Results: Versus C, T2DM was induced in mice received HFD and low dose STZ with significantly elevated blood glucose levels (T2: 388, T2/β 3 -ANT: 369 vs C: 128 mg/dl). In T2, LV myocyte basal function and [Ca 2+ ] iT regulation were impaired measured as significantly decreased myocyte contractility (dL/dt max ) (76.8 vs 135.2 μm/s), relengthening (dR/dt max ) (62.1 vs 113.8 μ m/s) and [Ca 2+ ] iT (0.16 vs 0.21). Furthermore, versus C, in T2 myocytes, ISO-induced increases in dL/dt max (T2: 40% vs C: 58%), dR/dt max (35% vs 54%) and [Ca 2+ ] iT (19% vs 30%) were significantly reduced. By contrary, versus T2, T2/β 3 -ANT myocytes showed normal basal cell contraction (127.8 μm/s), relaxation (109.4 μm/s) and [Ca 2+ ] iT (0.21) with preserved ISO-stimulated positive inotropic effect. Versus C, in T2/β 3 -ANT, ISO caused similar increases in dL/dt max (57%), dR/dt max (52%) and [Ca 2+ ] iT (30%). Conclusion: Chronic β 3 -ANT leads to the preservation of LV myocyte function, [Ca 2+ ] iT , and β-AR responsiveness in a mouse model of type 2 diabetes. Thus, antagonizing β 3 -AR might provide a new therapeutic strategy for DM-related decline in myocardial function.

Abstract 13035: Beta3-Adrenergic-Receptor-Deficient Mice Protected From Diabetic Cardiomyopathy in Type 2 Diabetic Murine Model: Beneficial Effects on Cardiomyocyte Contractile Function, [Ca 2+ ] i Regulation and Beta-Adrenergic Modulation

Background: Diabetic cardiomyopathy (DCM) is the main cause of increased mortality in Diabetes mellitus (DM). There are no effective therapeutic strategies. Recently, we found that DM is associated with the upregulation of β 3 adrenergic receptor (AR) mediated cardiac inhibitory pathway. This suggests cardiac β 3 -AR activation may contribute to DCM progression and be a therapeutic target. We hypothesize that upregulation of β 3 -AR is maladaptive, and DM-caused progressive decline in cardiac function and β-adrenergic reserve will be prevented in β 3 -AR knockout (β 3 KO) mice. Methods: Studies were conducted in female mice of 2 Vehicle controls groups (n=8/group) of wild-type (CWT) and Cβ 3 KO, and 2 Type 2 DM (T2) of T2WT (n=8) and T2β 3 KO (n=6).T2 was induced by fed high-fat diet (HFD) for 14 weeks (W), but after HFD for 4 W receiving streptozotocin (STZ, 40 mg/kg/day, i.p. for 5 days). We compared LV myocyte contractile and [Ca 2+ ] iT responses to β-AR subtype stimulation by random exposure of myocytes to the superfusion of isoproterenol (ISO,10 -8 M) or a selective β 1 -, or β 3 -agonist, Norepinephrine (NE, 10 -7 M), and BRL-37,344 (BRL, 10 -8 M), respectively. Results: Mice received HFD plus STZ developed T2DM with elevated mean blood glucose from 128 mg/dl of control to 388 mg/dl and 382 mg/dl in T2WT and T2β 3 KO, respectively. However only T2WT mice developed DCM followed by significant decreases in myocyte contraction (dL/dt max , T2WT: 74.8 vs CWT:140.1 μm/s), relaxation (dR/dt max , 58.0 vs 117.9 μm/s) and [Ca 2+ ] iT (0.16 vs 0.22). ISO-stimulated increases in dL/dt max (37% vs 58%), dR/dt max (30% vs 53%), and [Ca 2+ ] iT (19% vs 30%) were attenuated accompanied by a diminished NE-caused increase in dL/dt max (28% vs 41%), but enhanced BRL-induced decrease in dL/dt max (29% vs 15%). By contrary, T2β 3 KO showed normal basal dL/dt max (137.6 μm/s), dR/dt max (111.4 μm/s) and [Ca 2+ ] iT (0.22). Importantly, T2β 3 KO myocytes showed preserved ISO-stimulated increases in dL/dt max (60%), dR/dt max (51%) and [Ca 2+ ] iT (32%) and restored normal dL/dt max responses to NE (41%). Conclusions: β 3 KO prevents T2DM-caused contrast changes in β 1 - and β 3 -AR-stimulated cardiac inotropic actions and leading to the preservation of normal myocyte function, [Ca 2+ ] iT , and β-AR responsiveness in DCM.

Diabetic Cardiomyopathy: Clinical and Metabolic Approach.

Having in mind that diabetes mellitus (DM) and obesity are some of the greatest health challenges of the modern era, diabetic cardiomyopathy (DCM) is becoming more and more recognized in clinical practice. Main Text: Initially, DM is asymptomatic, but it may progress to diastolic and then systolic left ventricular dysfunction, which results in congestive heart failure. A basic feature of this DM complication is the absence of hemodynamically significant stenosis of the coronary blood vessels. Clinical manifestations are the result of several metabolic disorders that are present during DM progression. The complexity of metabolic processes, along with numerous regulatory mechanisms, has been the subject of research that aims at discovering new diagnostic (e.g. myocardial strain with echocardiography and cardiac magnetic resonance) and treatment options. Adequate glycaemic control is not sufficient to prevent or reduce the progression of DCM. Contemporary hypoglycemic medications, such as sodium-glucose transport protein 2 inhibitors, significantly reduce the frequency of cardiovascular complications in patients with DM. Several studies have shown that, unlike the above-stated medications, thiazolidinediones and dipeptidyl peptidase-4 inhibitors are associated with deterioration of heart failure. Imaging procedures, especially myocardial strain with echocardiography and cardiac magnetic resonance, are useful to identify the early signs of DCM. Research and studies regarding new treatment options are still "in progress".

NORAD regulates proliferation and apoptosis in cardiomyocytes under high-glucose treatment through miRNA-150-5p/ZEB1 axis.

The purpose of this study was to uncover the potential role of non-coding RNA activated by DNA damage (lncRNA NORAD) in the disease progression of diabetic cardiomyopathy (DCM) and the underlying mechanism. Cell viability, 5-Ethynyl-2'-deoxyuridine (EdU)-positive ratio and apoptotic rate in human cardiomyocyte cell line AC16 undergoing treatment of normal-level (NG) or high-level glucose (HG) were assessed at first. NORAD level in HG-induced AC16 cells at different time points was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Subsequently, cell viability, EdU-positive ratio, and apoptotic rate in HG-induced AC16 cells overexpressing NORAD were evaluated. Next, subcellular distribution of NORAD was examined, and Dual-Luciferase reporter gene assay was performed to clarify the interaction among NORAD, miRNA-150-5p, and ZEB1. At last, rescue experiments were conducted to clarify the role of NORAD/miRNA-150-5p/ZEB1 axis in influencing the proliferation and apoptosis in HG-induced AC16 cells. Results revealed that HG treatment suppressed the proliferative ability and stimulated apoptosis in AC16 cells. Besides, NORAD was time-dependently downregulated in HG-induced AC16 cells, and it was mainly distributed in cytoplasm. In addition, the overexpression of NORAD enhanced proliferative ability, attenuated apoptosis, and increased Bcl-2/Bax ratio in HG-induced AC16 cells. Finally, NORAD/miRNA-150-5p/ZEB1 axis was verified to protect the malignant progression of DCM. NORAD is upregulated under high-level glucose treatment. Overexpression of NORAD protects DCM development via miRNA-150-5p/ZEB1 axis.

Melatonin attenuates diabetic cardiomyopathy and reduces myocardial vulnerability to ischemia-reperfusion injury by improving mitochondrial quality control: Role of SIRT6.

Targeting mitochondrial quality control with melatonin has been found promising for attenuating diabetic cardiomyopathy (DCM), although the underlying mechanisms remain largely undefined. Activation of SIRT6 and melatonin membrane receptors exerts cardioprotective effects while little is known about their roles during DCM. Using high-fat diet-streptozotocin-induced diabetic rat model, we found that prolonged diabetes significantly decreased nocturnal circulatory melatonin and heart melatonin levels, reduced the expressions of cardiac melatonin membrane receptors, and decreased myocardial SIRT6 and AMPK-PGC-1α-AKT signaling. 16weeks of melatonin treatment inhibited the progression of DCM and the following myocardial ischemia-reperfusion (MI/R) injury by reducing mitochondrial fission, enhancing mitochondrial biogenesis and mitophagy via re-activating SIRT6 and AMPK-PGC-1α-AKT signaling. After the induction of diabetes, adeno-associated virus carrying SIRT6-specific small hairpin RNA or luzindole was delivered to the animals. We showed that SIRT6 knockdown or antagonizing melatonin receptors abolished the protective effects of melatonin against mitochondrial dysfunction as evidenced by aggravated mitochondrial fission and reduced mitochondrial biogenesis and mitophagy. Additionally, SIRT6 shRNA or luzindole inhibited melatonin-induced AMPK-PGC-1α-AKT activation as well as its cardioprotective actions. Collectively, we demonstrated that long-term melatonin treatment attenuated the progression of DCM and reduced myocardial vulnerability to MI/R injury through preserving mitochondrial quality control. Melatonin membrane receptor-mediated SIRT6-AMPK-PGC-1α-AKT axis played a key role in this process. Targeting SIRT6 with melatonin treatment may be a promising strategy for attenuating DCM and reducing myocardial vulnerability to ischemia-reperfusion injury in diabetic patients.

Autophagy Inhibition Enables Nrf2 to Exaggerate the Progression of Diabetic Cardiomyopathy in Mice.

Nuclear factor-erythroid factor 2-related factor 2 (Nrf2) may either ameliorate or worsen diabetic cardiomyopathy. However, the underlying mechanisms are poorly understood. Herein we report a novel mechanism of Nrf2-mediated myocardial damage in type 1 diabetes (T1D). Global Nrf2 knockout (Nrf2KO) hardly affected the onset of cardiac dysfunction induced by T1D but slowed down its progression in mice independent of sex. In addition, Nrf2KO inhibited cardiac pathological remodeling, apoptosis, and oxidative stress associated with both onset and advancement of cardiac dysfunction in T1D. Such Nrf2-mediated progression of diabetic cardiomyopathy was confirmed by a cardiomyocyte-restricted (CR) Nrf2 transgenic approach in mice. Moreover, cardiac autophagy inhibition via CR knockout of autophagy-related 5 gene (CR-Atg5KO) led to early onset and accelerated development of cardiomyopathy in T1D, and CR-Atg5KO-induced adverse phenotypes were rescued by additional Nrf2KO. Mechanistically, chronic T1D leads to glucolipotoxicity inhibiting autolysosome efflux, which in turn intensifies Nrf2-driven transcription to fuel lipid peroxidation while inactivating Nrf2-mediated antioxidant defense and impairing Nrf2-coordinated iron metabolism, thereby leading to ferroptosis in cardiomyocytes. These results demonstrate that diabetes over time causes autophagy deficiency, which turns off Nrf2-mediated defense while switching on an Nrf2-operated pathological program toward ferroptosis in cardiomyocytes, thereby worsening the progression of diabetic cardiomyopathy.

Isoliquiritigenin attenuates diabetic cardiomyopathy via inhibition of hyperglycemia-induced inflammatory response and oxidative stress

Inflammation and oxidative stress play essential roles in the occurrence and progression of diabetic cardiomyopathy (DCM). Isoliquiritigenin (ISL), a natural chalcone, exhibits strong anti-inflammatory and antioxidant activities. In this study, we aimed to investigate the protective effects of ISL on DCM using high glucose (HG)-challenged cultured cardiomyocytes and streptozotocin (STZ)-induced diabetic mice. Embryonic rat heart-derived H9c2 cells challenged with a high concentration of glucose were used to evaluate the anti-inflammatory and antioxidant effects of ISL. STZ-induced diabetic mice were used to study the effects of ISL in DCM in vivo. Furthermore, cardiac fibrosis, hypertrophy, and apoptosis were explored both in vitro and in vivo. ISL effectively inhibited HG-induced hypertrophy, fibrosis, and apoptosis probably by alleviating the inflammatory response and oxidative stress in H9c2 cells. Results from in vivo experiments showed that ISL exhibited anti-inflammatory and antioxidant stress activities that were characterized by the attenuation of cardiac hypertrophy, fibrosis, and apoptosis, which resulted in the maintenance of cardiac function. The protective effects of ISL against inflammation and oxidative stress were mediated by the inhibition of mitogen-activated protein kinases (MAPKs) and induction of nuclear factor-erythroid 2 related factor 2 (Nrf2) signaling pathway, respectively. Our results provided compelling evidence that ISL, by virtue of neutralizing excessive inflammatory response and oxidative stress, could be a promising agent in the treatment of DCM. Targeting the MAPKs and Nrf2 signaling pathway might be an effective therapeutic strategy for the prevention and treatment of DCM.

Mitochondrial Dysfunction in Diabetic Cardiomyopathy: The Possible Therapeutic Roles of Phenolic Acids.

As the powerhouse of the cells, mitochondria play a very important role in ensuring that cells continue to function. Mitochondrial dysfunction is one of the main factors contributing to the development of cardiomyopathy in diabetes mellitus. In early development of diabetic cardiomyopathy (DCM), patients present with myocardial fibrosis, dysfunctional remodeling and diastolic dysfunction, which later develop into systolic dysfunction and eventually heart failure. Cardiac mitochondrial dysfunction has been implicated in the development and progression of DCM. Thus, it is important to develop novel therapeutics in order to prevent the progression of DCM, especially by targeting mitochondrial dysfunction. To date, a number of studies have reported the potential of phenolic acids in exerting the cardioprotective effect by combating mitochondrial dysfunction, implicating its potential to be adopted in DCM therapies. Therefore, the aim of this review is to provide a concise overview of mitochondrial dysfunction in the development of DCM and the potential role of phenolic acids in combating cardiac mitochondrial dysfunction. Such information can be used for future development of phenolic acids as means of treating DCM by alleviating the cardiac mitochondrial dysfunction.

Acupuncture Reduces Hypertrophy and Cardiac Fibrosis, and Improves Heart Function in Mice with Diabetic Cardiomyopathy.

To assess the effects of electro-acupuncture (EA) on glycemic control, myocardial inflammation, and the progression of diabetic cardiomyopathy in mice with type 2 diabetes. Db/Db mice received EA at PC6+ST36 (DM-Acu), non-acupoint simulation (DM-Sham), or no treatment (DM). EA was applied for 30min per day, 5days a week for 4weeks. Heart function was assessed by echocardiography. Myocardium was assessed by RT-PCR, immunoblotting, and histology. Serum TNF-α, IL-1α, IL-1β, IL-6, and IL-8 were measured. DM-Acu, but not DM-Sham, reduced fasting blood glucose without affecting body weight. DM decreased systolic function. DM-Acu, but not DM-Sham, attenuated the decrease in systolic function. Heart weight was significantly smaller in the DM-Acu than in the DM and DM-Sham groups. Percent fibrosis and apoptosis were reduced in the DM-Acu, but not the DM-Sham, group. Serum levels of IL-1α, IL-1β, IL-6, IL-8, ICAM-1, MCP-1, and TNF-α were significantly lower in the DM-Acu than in the DM or DM-Sham groups. Protein levels of P-Akt and P-AMPK and mRNA levels of phosphoinositide-3-kinase regulatory subunit 6 (PIK3r6) were significantly higher in the DM-Acu group. Myocardial mRNA and protein levels of insulin-like growth factor 1 receptor (IGF1R) were significantly lower in the DM and DM-Sham groups compared with the DM-Acu group. EA reduced serum glucose; prevented DM-induced hypertrophy and deterioration of systolic function, inflammation, and fibrosis; and restored IGF1R, P-Akt, and P-AMPK levels in mice with type 2 diabetes mellitus.

Application of untargeted lipidomics based on UHPLC-high resolution tandem MS analysis to profile the lipid metabolic disturbances in the heart of diabetic cardiomyopathy mice

Diabetic cardiomyopathy (DCM) is a distinct form of heart disease caused by diabetes. Lipid accumulation has been reported to present in the hearts of DCM animals, however characterization of disordered lipids, and their roles in the etiology and progress of DCM remain largely undefined. In present study, an untargeted lipidomics based on ultra-high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometers was established for global detection of lipids in the hearts of DCM mice. DCM mice showed significant cardiac dysfunction with decreased left ventricular fractional shortening (FS) and ratio of peak early filling velocity to atrial filling velocity (MV E/A). Histological lesion, fibrosis, hypertrophy, and lipid accumulation were also observed in the heart of DCM mice. By lipidomics analysis, a total of 244 lipids were identified, of which 89 lipids were significantly changed. The disordered metabolic profile of lipids in DCM mice heart were characterized by the accumulation of triacylglycerol, glycerophospholipid, cholesterol-sulfate, ceramide and sphingomyelin, as well as by the loss of glycerophospholipid. The lipid alterations in the heart were correlated with the development of cardiac dysfunction, lipotoxicity, inflammation and insulin resistance. Correlations between lipid metabolism disorders and DCM progress should be further explored.

Abstract 220: Emerging Roles of Altered NAD Metabolism in Diabetic Cardiomyopathy

Diabetes is linked to altered NAD metabolism whose causal roles in cardiac dysfunction are poorly understood. Synthesis, consumption and redox balance of NAD dictate NAD metabolism and its homeostasis, and we here explored their roles in diabetic cardiomyopathy. 16 week of Type 1 diabetes (T1D) to C57BL6N mice was associated with lowered cardiac NAD/NADH, mild systolic and more severe diastolic dysfunction. We next used mouse models with altered NAD metabolism to determine how NAD redox balance impacts diabetic cardiomyopathy. Using cardiac-specific Ndufs4-KO mice (cKO) as a model of latent decrease in cardiac NAD/NADH, we observed accelerated systolic and diastolic dysfunction (lowered fractional shortening, E’/A’ ratio, and increased e/E’ ratio) in male cKO mice stressed with chronic T1D. Cardiac hypertrophy (heart weight/tibia length), insulin depletion and hyperglycemia levels were similar in these mice. Serum metabolomic analyses (~240 metabolites) also showed unchanged aqueous and lipid metabolite levels, suggesting that the diabetic stresses on these hearts were similar. The accelerated dysfunction of T1D cKO hearts was also observed in another female cohort. Importantly, elevation of cardiac NAD levels to attenuate NAD redox imbalance mitigated the accelerated dysfunction of T1D cKO hearts. In another cohort, control and cKO mice were stressed by 16-week high fat diet feeding. Accelerated systolic and diastolic dysfunction, and increased hypertrophy were observed in T2D cKO mice with similar glycemic levels to control mice. The data suggested that NAD redox imbalance is a positive regulator of cardiac dysfunction induced by T1D or T2D. However, NAD-dependent pathogenic mechanism induced by T1D or T2D (e.g. hypertrophy) can be different, and is under further investigation. Tissue fibrosis and mRNA levels of pro-fibrotic genes, including Adamts proteinases, integrins, laminins, matrix metalloproteinases and collagens were unchanged in T1D cKO hearts. Therefore, the accelerated dysfunction of T1D cKO hearts is due to cardiomyocyte dysfunction. We examined how NAD metabolism, other than the redox balance, may alter cardiomyocyte function. Levels of metabolite and mRNA regulating NAD synthesis and consumption pathways were measured. Of 32 transcripts assayed, Nmrk2 levels were uniquely up-regulated in T1D cKO hearts, and lowered by elevation of cardiac NAD levels. NMRK product levels were concomitantly decreased in T1D cKO hearts. NAD-dependent global acetylation and inhibitory superoxide dismutase 2 acetylation were increased in T1D cKO hearts. Protein oxidation levels were concomitantly raised. Hyperacetylation in proteins like CaM kinase was associated with increased phosphorylation in troponin I, not in MyBPC or PLN in T1D cKO hearts. These data support the emerging, multifaceted roles of altered NAD metabolism in the progression of diabetic cardiomyopathy.

The Mitochondria: A Target of Polyphenols in the Treatment of Diabetic Cardiomyopathy.

Diabetic cardiomyopathy (DCM) is a constellation of symptoms consisting of ventricular dysfunction and cardiomyocyte disarray in the presence of diabetes. The exact cause of this type of cardiomyopathy is still unknown; however, several processes involving the mitochondria, such as lipid and glucose metabolism, reactive oxygen species (ROS) production, apoptosis, autophagy and mitochondrial biogenesis have been implicated. In addition, polyphenols have been shown to improve the progression of diabetes. In this review, we discuss some of the mechanisms by which polyphenols, particularly resveratrol, play a role in slowing the progression of DCM. The most important intermediates by which polyphenols exert their protective effect include Bcl-2, UCP2, SIRT-1, AMPK and JNK1. Bcl-2 acts to attenuate apoptosis, UCP2 decreases oxidative stress, SIRT-1 increases mitochondrial biogenesis and decreases oxidative stress, AMPK increases autophagy, and JNK1 decreases apoptosis and increases autophagy. Our dissection of these molecular players aims to provide potential therapeutic targets for the treatment of DCM.

89-OR: FGFR1/MAPKs/AP-1 Signaling Mediates Cardiomyopathy in Streptozotocin-Induced Type 1 Diabetes

Diabetic cardiomyopathy is a complex entity associated with multiple contributing mechanisms and consequent manifestations in the clinic. Emerging evidence implicates that increased activity of fibroblast growth factor receptor 1 (FGFR1) is required during induced cardiac damage and remodeling. However, little is known about the roles of FGFR1 on diabetic cardiomyopathy (DCM). We hypothesized that the high-concentration glucose (HG)/diabetes induced cardiac pathophysiological and malfunctional alterations are linked to the activation of FGFR1. We tested this hypothesis by challenging cultured cardiomyocytes with high-concentration glucose and myocardium of streptozotocin (STZ)-induced type 1 diabetic mice (T1D). This study indicated that FGFR1 phosphorylation was increased in myocardium of streptozotocin (STZ)-induced type 1 diabetic mice (T1D) and cultured cardiomyocytes to high-concentration glucose. The inactivation of FGFR1 by selective inhibitors AZD4547, neutralized the increased FGFR1 phosphorylation and significantly reduced myocardial structural and functional deficits in type 1 diabetic mice. In vitro, overexpression of FGFR1 by lentivirus-transfection aggravated HG-induced fibrosis and hypertrophy in cardiomyocytes. Blocking FGFR1 by AZD4547 or CRISPER-Cas9 knockout, HG-induced fibrosis and hypertrophy in cardiomyocytes were significantly decreased. Then, GSEA analysis of RNA-sequencing implied that collagen5a1(Col5a1) and periostin (Postn) were associated with fibrosis and myosin heavy chain 4/7/8/9 (Myh4/7/8/9) were associated with hypertrophy. Analysis by PASTAA database and confirmatory tests by inhibiting FGFR1 or MAPKs indicated that MAPKs/AP-1 plays a crucial role in FGkFR1-mediated cardiomyocyte injuries challenged by HG. These results reveal an unrecognized FGFR1/MAPKs/AP-1 signaling axis involved in the development and progression of DCM and suggest that AZD4547 might be a potential agent for treating DCM. Disclosure X. Chen: None. Y. Wang: None. F. Shen: None. Funding National Natural Science Foundation of China (81700335)

Bauhinia variegata leaf extract: An effective management option for diabetic cardiomyopathy

Hyperglycemia, hyperlipidemia, and oxidative stress are an important pathological conditions in diabetes which are linked with the progression of diabetic cardiomyopathy. Cardiomyopathy is considered as one of the major cause of mortality in diabetic patients. The present study focuses on the effect of Bauhinia variegata Linn leaves in the management of diabetic cardiomyopathy. Alcoholic extract of Bauhinia variegata Linn leaves (AlcE) was prepared and standardized using liquid chromatography-mass spectroscopy (LC-MS) analysis. Male Sprague Dawley rats received a single intraperitoneal injection of streptozotocin (55 mg/kg) for induction of diabetes. After 6 weeks of diabetes induction, animals were treated with AlcE at the dose of 250, 500 and 1000 mg/kg by oral route for next 28 days. Diabetic control animals showed a significant increased level of blood glucose (P<0.001) when compared with normal control. Treatment with AlcE at dose 500 and 1000 mg/kg significantly reduced the elevated blood glucose (521.0 ± 8.40 and 459.3 ± 49.42, respectively) after 28 days of treatment (p<0.05 and p<0.001). Diabetic control group also showed significant increased level of cardiac marker enzyme-like aspartate transaminase (299.7 ± 17.0), lactate dehydrogenase (1235±40.39), creatinine kinase- MB (1081±42.49) in plasma. Treatment with AlcE at dose 1000 mg/kg significantly reduced the elevated level of aspartate transaminase (194.4 ± 12.27), lactate dehydrogenase (872.3 ± 28.58) and creatinine kinase- MB (735.5 ± 38.35) (p<0.001, p<0.001 and p<0.001, respectively). Elevated lipid markers like total cholesterol and triglyceride were found to be significantly attenuated after AlcE treatment at dose 1000 mg/kg (p<0.001 and p<0.05, respectively). AlcE treatment also significantly prevented the loss of antioxidant enzymes like superoxide dismutase, catalase and glutathione and reduced formation of lipid malondialdehyde in cardiac tissue (p<0.01, p<0.00, p<0.001 and P<0.001). Restoration of altered electrocardiogram pattern and hemodynamic parameters were also observed after AlcE treatment. Histopathological findings indicated that AlcE treatment prevented cardiac tissue from necrotic damage and collagen deposition.Form the results, it can be concluded that Bauhinia variegata extract is having significant effect in the management of diabetic cardiomyopathy.

Sex Differences in Progression of Diabetic Cardiomyopathy in OVE26 Type 1 Diabetic Mice.

OVE26 mice are a widely used transgenic model of early-onset type 1 diabetes. These mice overexpress calmodulin in their pancreatic β cells, develop severe diabetes within the first weeks of life, and progress to severe diabetic complications including diabetic nephropathy and diabetic cardiomyopathy (DCM). To date, diabetic nephropathy in OVE26 mice has been well explored, leaving the progression of DCM and the gender impact in this type 1 diabetes model still unrevealed. In our study, male and female OVE26 mice and age-matched nondiabetic FVB mice were examined at 4, 12, 24, and 36 weeks for their cardiac function, body weight, blood glucose, and heart weight/tibia length ratio. Further, histopathological examination and Western blot analysis for the key markers demonstrate that DCM appears at 24 weeks OVE26 mice, initiating with cardiac senescence, followed by fibrosis and then cardiac dysfunction. Mitochondrial respiration function analysis showed no indication of dysfunction in OVE26 mice at 24 weeks of age in both genders. In addition, no significant difference for the pathogenic progression was observed between OVE26 and FVB mice in both males and females. In conclusion, this study suggests cardiac senescence and fibrosis, which may be amended by sex differences, play key roles in the progression of DCM in OVE26 mice. The comprehensive characterization of diabetic cardiomyopathy progression and the sex difference impact in OVE26 mice provides a basis for future study on DCM using OVE26 mice.