Metabolic and Biochemical Stressors in Diabetic Cardiomyopathy

FUNDC1: An Emerging Mitochondrial and MAMs Protein for Mitochondrial Quality Control in Heart Diseases

Heart diseases (HDs) are the leading cause of mortality worldwide, with mitochondrial dysfunction being a significant factor in their development. The recently discovered mitophagy receptor, FUNDC1, plays a critical role in regulating the homeostasis of the Mitochondrial Quality Control (MQC) system and contributing to HDs. The phosphorylation of specific regions of FUNDC1 and varying levels of its expression have been shown to have diverse effects on cardiac injury. This review presents a comprehensive consolidation and summary of the latest evidence regarding the role of FUNDC1 in the MQC system. The review elucidates the association of FUNDC1 with prevalent HDs, such as metabolic cardiomyopathy (MCM), cardiac remodeling/heart failure, and myocardial ischemia-reperfusion (IR) injury. The results indicate that the expression of FUNDC1 is elevated in MCM but reduced in instances of cardiac remodeling, heart failure, and myocardial IR injury, with divergent impacts on mitochondrial function among distinct HDs. Exercise has been identified as a powerful preventive and therapeutic approach for managing HDs. Additionally, it has been suggested that exercise-induced enhancement of cardiac function may be attributed to the AMPK/FUNDC1 pathway.

Cathelicidin-WA ameliorates diabetic cardiomyopathy by inhibiting the NLRP3 inflammasome

Cathelicidin-WA (CWA) is a novel cathelicidin peptide isolated from snakes that has been suggested to exert anti-inflammatory effects. The aim of our study was to investigate whether cathelicidin-WA (CWA) could protect the heart from diabetic cardiomyopathy (DCM). Streptozotocin (STZ) injection was used to establish a mouse model of DCM. CWA peptide (2 mg/kg or 8 mg/kg) was continuously administered to the mice from 10 weeks to 16 weeks after STZ injection. The mice in the DCM group exhibited cardiac dysfunction, while 8 mg/kg CWA ameliorated this cardiac dysfunction. Cardiac fibrosis, inflammation, and oxidative stress as well as cardiomyocyte apoptosis in the DCM mice were decreased by treatment with 8 mg/kg CWA. We isolated neonatal rat cardiomyocytes and stimulated the cells with high glucose to establish an in vitro model of myocyte cell injury. Consistently, CWA inhibited high glucose-induced cell death, inflammation and oxidative stress in the myocytes. Moreover, CWA reduced the formation of the NLR family pyrin domain-containing 3 (NRLP3) inflammasome by regulating thioredoxin-interacting protein expression and p65 activation. NLRP3 overexpression inhibited the beneficial effects of CWA on the heart during DCM and on high glucose-induced myocyte injury. In summary, CWA attenuates cardiac injury and preserves cardiac function during DCM by targeting the NLRP3 pathway.Abbreviations: AAV9: Adeno associated virus; AGE: Advanced Glycation End products; CWA: Cathelicidin-WA; DCM: diabetic cardiomyopathy; Gpx: glutathione peroxidase; HG: high glucose; IL: Interleukin; NLR: Family Pyrin Domain Containing 3 (NRLP3); TXNIP: Thioredoxin interacting protein; LVEF: left ventricular ejection fraction; MDA: Malondialdehyde; MnSOD: manganese superoxide dismutase; NADPH: Nicotinamide adenine dinucleotide phosphate; NAC: N-acetyl-cysteine; NRCMs: Neonatal rat cardiomyocytes; ROS: reactive oxygen species; STZ: Streptozotocin; TNFa: tumor necrosis factor a.

Effects of platelet rich plasma on experimentally induced diabetic heart injury

Diabetic heart is one of the common complications of diabetes mellitus. Platelet-rich plasma (PRP) is an autologous product rich in growth factors that can enhance tissue regeneration. This work was conducted to study the PRP ability to improve diabetes-inducing cardiac changes. Also, it sheds more light on the possible mechanisms through which PRP induces its effects. Rats were divided into; control, PRP, diabetic, and PRP-diabetic groups. Cardiac specimens were obtained and processed for biochemical, histological, and immunohistochemical study. The diabetic group exhibited a significant increase in cardiac oxidative stress, inflammation, and cardiac injury markers if compared with the control group. Additionally, the cardiac tissue showed variable morphological changes in the form of focal distortion and loss of cardiac myocytes. Distorted mitochondria and heterochromatic nuclei were observed in the cardiac muscle fibers. The mean number of charcoal-stained macrophages, and mean area fraction for collagen fibers, mean number of PCNA-immune positive cardiac muscle were significantly decrease in PRP- diabetic group. Collectively, the results showed that PRP treatment ameliorated most of all these previous changes. CONCLUSION: PRP ameliorated the diabetic cardiac injury via inhibition of oxidative stress and inflammation. It was confirmed by biochemical, histological, and immunohistochemical study. It could be concluded that PRP could be used as a potential therapy for diabetic heart.

Re-evaluating the causes and consequences of non-resolving inflammation in chronic cardiovascular disease

Cardiac injuries, like heart attacks, drive the secondary pathology with advanced heart failure. In this process, non-resolving inflammation is a prime component of accelerated cardiovascular disease and subsequent fatal events associated with imbalanced diet, physical inactivity, disrupted circadian rhythms, neuro-hormonal stress, and poly- or co-medication. Laboratory rodents have established that splenic leukocyte-directed resolution mechanisms are essential for cardiac repair after injury. Here, we discuss the impact of three lifestyle-related factors that are prime causes of derailed cardiac healing, putative non-resolving inflammation-resolution mechanisms in cardiovascular diseases, and progressive heart failure after cardiac injury. The presented review resurfaces the lifestyle-related risks and future research directions required to understand the molecular and cellular mechanisms between the causes of cardiovascular disease and their related consequences of non-resolving inflammation.

The Peroxisome Proliferator-Activated Receptor-Gamma Coactivator-1α-Heme Oxygenase 1 Axis, a Powerful Antioxidative Pathway with Potential to Attenuate Diabetic Cardiomyopathy

Significance: From studies of diabetic animal models, the downregulation of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α)-heme oxygenase 1 (HO-1) axis appears to be a crucial event in the development of obesity and diabetic cardiomyopathy (DCM). In this review, we discuss the role of metabolic and biochemical stressors in the rodent and human pathophysiology of DCM. A crucial contributor for many cardiac pathologies is excessive production of reactive oxygen species (ROS) pathologies, which lead to extensive cellular damage by impairing mitochondrial function and directly oxidizing DNA, proteins, and lipid membranes. We discuss the role of ROS production and inflammatory pathways with multiple contributing and confounding factors leading to DCM. Recent Advances: The relevant biochemical pathways that are critical to a therapeutic approach to treat DCM, specifically caloric restriction and its relation to the PGC-1α-HO-1 axis in the attenuation of DCM, are elucidated. Critical Issues: The increased prevalence of diabetes mellitus type 2, a major contributor to unique cardiomyopathy characterized by cardiomyocyte hypertrophy with no effective clinical treatment. This review highlights the role of mitochondrial dysfunction in the development of DCM and potential oxidative targets to attenuate oxidative stress and attenuate DCM. Future Directions: Targeting the PGC-1α-HO-1 axis is a promising approach to ameliorate DCM through improvement in mitochondrial function and antioxidant defenses. A pharmacological inducer to activate PGC-1α and HO-1 described in this review may be a promising therapeutic approach in the clinical setting.

Reactive Carbonyl Species: Diabetic Complication in the Heart and Lungs

Abnormal chemical reactions in hyperglycemia alter normal metabolic processes in diabetes, which is a key process in the production of reactive carbonyls species (RCS). Increasing the concentration of RCS may result in carbonyl/oxidative stress in both the diabetic heart and lung. Ryanodine receptors (RyRs) not only play a key role in heart contraction, including rhythmic contraction and relaxation of the heart, but they are also important for controlling the airway smooth muscle. RCS modifies RyRs, resulting in RyRs dysfunction, which is involved in important mechanisms in diabetic complications. Very little is known about the mechanistic relationship between the heart and lung in diabetes. This review highlights new findings on the pathophysiological mechanisms and discusses potential approaches to treatment for these complications.

Qishen Yiqi Drop Pill, a novel compound Chinese traditional medicine protects against high glucose-induced injury in cardiomyocytes

OBJECTIVE

Qishen Yiqi Drop Pill (QSYQ) has been recognized as a potential protective agent for various cardiovascular diseases. However, the effect of QSYQ in cardiac complications associated with diabetes is not clear currently. In this study, we investigate whether QSYQ could exert cardiac protective effects against high glucose-induced injuries in cardiac H9c2 cells.

METHODS

H9c2 cells were exposed to 24 hours of high glucose in presence or absence of QSYQ and LY294002. Cell cytotoxicity, apoptosis, reactive oxygen species (ROS) generation, mitochondrial membrane potential and mitochondrial permeability transition pore (mPTP) opening were determined. Levels of bax, bcl-2, p53, cleaved caspase-3, PI3K and Akt were evaluated by Western blot.

RESULTS

Our data indicated that QSYQ significantly increased the cell viability and decreased cytotoxicity. By analysing the apoptotic rate as well as the expression levels of cytoapoptosis-related factors including cleaved caspase-3, bax, bcl-2, and p53, we found that QSYQ could remarkably suppress apoptosis of cardiomyoblasts caused by high glucose. In addition, it also showed that QSYQ reduced the generation of ROS. We further found that QSYQ treatment could inhibit the loss of mitochondrial membrane potential and mPTP opening. Moreover, Western blot analysis showed enhanced phosphorylation of PI3K/Akt. The specific inhibitor of PI3K, LY294002 not only inhibited QSYQ induced PI3K/Akt signalling pathway activation, but alleviated its protective effects.

CONCLUSIONS

In summary, these findings demonstrated that QSYQ effectively protected H9c2 cells against the series injuries due to high glucose at least partially by activating the PI3K/Akt signalling pathway.

Exogenous Pancreatic Kallikrein Improves Diabetic Cardiomyopathy in Streptozotocin-Induced Diabetes

Aims: To evaluate the protective effects of exogenous pancreatic kallikrein (PKK) treatment on diabetic cardiomyopathy (DCM) and explore the underlying mechanisms. Methods and Results: Streptozotocin (STZ)-induced diabetic rats, a type 1 diabetic model, were treated with either PKK or saline for 12 weeks. Non-diabetic rats were used as controls. PKK administration attenuated the mitochondria swelling, Z line misalignments, myofibrosis and interstitial collagen accumulation in diabetic myocardial tissue. The oxidative stress imbalance including increased nitrotyrosine, decreased anti-oxidative components such as nuclear receptor nuclear factor like 2 (Nrf2), glutathione peroxidase 1(GPx-1), catalase (CAT) and superoxide dismutase (SOD), were recovered in the heart of PKK-treated diabetic rats. In diabetic rats, protein expression of TGF-β1 and accumulation of collagen I in the heart tissues was decreased after PKK administration. Markers for inflammation were decreased in diabetic rats by PKK treatment. Compared to diabetic rats, PKK reversed the degradation of IκB-α, an inhibitive element of heterotrimer nuclear factor kappa B (NF-κB). The endothelial nitric oxide synthase (eNOS) protein and myocardial nitrate/nitrite were impaired in the heart of diabetic rats, which, however, were restored after PKK treatment. The sarcoplasmic reticulum Ca²⁺-ATPase 2 (SERCA2) and phospholamban (PLN) were mishandled in diabetic rats, while were rectified in PKK-treated diabetic rats. The plasma NT-proBNP level was increased in diabetic rats while was reduced with PKK treatment. Conclusion: PKK protects against DCM via reducing fibrosis, inflammation, and oxidative stress, promoting nitric oxide production, as well as restoring the function of the calcium channel.

Paradigm shift - Metabolic transformation of docosahexaenoic and eicosapentaenoic acids to bioactives exemplify the promise of fatty acid drug discovery

Fatty acid drug discovery (FADD) is defined as the identification of novel, specialized bioactive mediators that are derived from fatty acids and have precise pharmacological/therapeutic potential. A number of reports indicate that dietary intake of omega-3 fatty acids and limited intake of omega-6 promotes overall health benefits. In 1929, Burr and Burr indicated the significant role of essential fatty acids for survival and functional health of many organs. In reference to specific dietary benefits of differential omega-3 fatty acids, docosahexaenoic and eicosapentaenoic acids (DHA and EPA) are transformed to monohydroxy, dihydroxy, trihydroxy, and other complex mediators during infection, injury, and exercise to resolve inflammation. The presented FADD approach describes the metabolic transformation of DHA and EPA in response to injury, infection, and exercise to govern uncontrolled inflammation. Metabolic transformation of DHA and EPA into a number of pro-resolving molecules exemplifies a novel, inexpensive approach compared to traditional, expensive drug discovery. DHA and EPA have been recommended for prevention of cardiovascular disease since 1970. Therefore, the FADD approach is relevant to cardiovascular disease and resolution of inflammation in many injury models. Future research demands identification of novel action targets, receptors for biomolecules, mechanism(s), and drug-interactions with resolvins in order to maintain homeostasis.

Diabetic Cardiomyopathy: Impact of Biological Sex on Disease Development and Molecular Signatures

Diabetic cardiomyopathy refers to a unique set of heart-specific pathological variables induced by hyperglycemia and insulin resistance. Given that cardiovascular disease (CVD) is the leading cause of death in the world, and type 2 diabetes incidence continues to rise, understanding the complex interplay between these two morbidities and developing novel therapeutic strategies is vital. Two hallmark characteristics specific to diabetic cardiomyopathy are diastolic dysfunction and cardiac structural mal-adaptations, arising from cardiac cellular responses to the complex toxicity induced by hyperglycemia with or without hyperinsulinemia. While type 2 diabetes is more prevalent in men compared to women, cardiovascular risk is higher in diabetic women than in diabetic men, suggesting that diabetic women take a steeper path to cardiomyopathy and heart failure. Accumulating evidence from randomized clinical trials indicate that although pre-menopausal women have lower risk of CVDs, compared to age-matched men, this advantage is lost in diabetic pre-menopausal women, which suggests estrogen availability does not protect from increased cardiovascular risk. Notably, few human studies have assessed molecular and cellular mechanisms regarding similarities and differences in the progression of diabetic cardiomyopathy in men versus women. Additionally, most pre-clinical rodent studies fail to include female animals, leaving a void in available data to truly understand the impact of biological sex differences in diabetes-induced dysfunction of cardiovascular cells. Elegant reviews in the past have discussed in detail the roles of estrogen-mediated signaling in cardiovascular protection, sex differences associated with telomerase activity in the heart, and cardiac responses to exercise. In this review, we focus on the emerging cellular and molecular markers that define sex differences in diabetic cardiomyopathy based on the recent clinical and pre-clinical evidence. We also discuss miR-208a, MED13, and AT2R, which may provide new therapeutic targets with hopes to develop novel treatment paradigms to treat diabetic cardiomyopathy uniquely between men and women.

Inhibition of miR-186-5p contributes to high glucose-induced injury in AC16 cardiomyocytes

A growing body of evidence has demonstrated that microRNAs (miRs) have pivotal roles in the pathophysiological development mechanisms of diabetic cardiomyopathy (DCM). Previous studies have demonstrated that miR-186-5p was significantly decreased in DCM. In addition, it has recently been reported that an imbalance of miR-186 is associated with a variety of physiological and pathological processes. Therefore, the present study was designed to investigate the role of miR-186-5p in high glucose (HG)-induced cytotoxicity and apoptosis in AC16 cardiomyocytes. Reverse transcription-polymerase chain reaction was used to demonstrate the significant decrease in the level of miR-186-5p in HG-treated AC16 cells (P<0.05). Subsequently, it was clarified that pre-transfection with miR-186-5p mimic significantly ameliorated the effects of high glucose, which induced a significant decrease in the viability of AC16 cells (P<0.05) and increases in apoptosis, as evidenced by the appearance of apoptotic nucleus and the significant upregulation of apoptosis rate in AC16 cells (P<0.05). In addition, the significantly increased expression of caspase-3 induced by HG (P<0.01) was also reversed by miR-186-5p mimic (P<0.01). Conversely, transfection with miR-186-5p inhibitor significantly reduced the viability of AC16 cells (P<0.05) and promoted apoptosis (P<0.05) as well as the expression of caspase-3 in AC16 cells (P<0.01), indicating the beneficial role of miR-186-5p in the physiological process of HG-induced damage. In conclusion, these results suggest that the distribution of miR-186-5p contributes to HG-induced cytotoxicity and apoptosis in AC16 cardiomyocytes.