Ghrelin ameliorates cardiac fibrosis after myocardial infarction by regulating the Nrf2/NADPH/ROS pathway

Single-cell sequencing reveals LRRc17-mediated modulation of cardiac fibroblast ferroptosis in regulating myocardial fibrosis after myocardial infarction

PURPOSE

Myocardial fibrosis after myocardial infarction (MI) is one of the main causes of death in patients, but there is no effective treatment for myocardial fibrosis at present. Hence, it is important to elucidate the pathogenesis of fibrosis after MI and find therapeutic targets for regulating ventricular remodeling after MI.

METHODS

Differentially expressed gene analysis, weighted Gene co-expression network analysis (WGCNA) and differential gene analysis in cardiac fibroblasts (CFs) were performed on the MI-related data (GSE153485 and GSE210159) from the GEO database to screen the hub genes related to ferroptosis in MI. After the establishment of MI model in vivo and in vitro, the myocardial CFs were observed by Masson staining, hematoxylin-eosin staining, CCK-8, and Transwell, and the changes of LRRc17 and ferroptosis-related proteins were detected by qRT-PCR and Western blotting. The expression of ROS was detected by fluorescence dye method.

RESULTS

Three DEGs were identified in MI related to ferroptosis, among which LRRc17 was selected for subsequent study. In both in vitro and in vivo models of MI, we found a sustained downregulation of LRRc17 expression and the expression of ferroptosis-related proteins GPX-4 and xCT, but increased ROS expression and enhanced migration and viability of CFs. After oe-LRRc17 treatment, the expression levels of GPX-4 and xCT were restored, while ROS levels were inhibited, and the migration and viability of CFs were inhibited. After treatment with ferroptosis inducer Erastin, there were down-regulated expressions of GPX-4 and xCT, increased expression of ROS, and enhanced migration and viability of CFs.

CONCLUSION

LRRc17 affects ventricular remodeling by mediating ferroptosis in CFs to regulate the degree of fibrosis after MI.

Fucoxanthin inhibits cardiac fibroblast transdifferentiation by alleviating oxidative stress through downregulation of BRD4

Myocardial fibrosis can lead to ischemic damage of the myocardium, which can be life-threatening in severe cases. Cardiac fibroblast (CF) transdifferentiation is an important process in myocardial fibrosis. Fucoxanthin (FX) plays a key role in ameliorating myocardial fibrosis; however, its mechanism of action is not fully understood. This study investigated the role of FX in the angiotensin II (Ang II)-induced transdifferentiation of CFs and its potential mechanisms of action. We found that FX inhibited Ang II-induced transdifferentiation of CFs. Simultaneously, FX downregulated bromodomain-containing protein 4 (BRD4) expression in CFs and increased nuclear expression of nuclear factorerythroid 2-related factor 2 (Nrf2). FX reverses AngII-induced inhibition of the Keap1/Nrf2/HO-1 pathway and elevates the level of reactive oxygen species (ROS). FX failed to reverse Ang II-induced changes in fibrosis-associated proteins and ROS levels after Nrf2 silencing. BRD4 silencing reversed the inhibitory effect of Ang II on the Keap1/Nrf2/HO-1 antioxidant signalling pathway. In conclusion, we demonstrated that FX inhibited Ang II-induced transdifferentiation of CFs and that this effect may be related to the activation of the Keap1/Nrf2/HO-1 pathway by reducing BRD4 expression and, ultimately, oxidative stress.

Post-myocardial infarction fibrosis: Pathophysiology, examination, and intervention

Cardiac fibrosis plays an indispensable role in cardiac tissue homeostasis and repair after myocardial infarction (MI). The cardiac fibroblast-to-myofibroblast differentiation and extracellular matrix collagen deposition are the hallmarks of cardiac fibrosis, which are modulated by multiple signaling pathways and various types of cells in time-dependent manners. Our understanding of the development of cardiac fibrosis after MI has evolved in basic and clinical researches, and the regulation of fibrotic remodeling may facilitate novel diagnostic and therapeutic strategies, and finally improve outcomes. Here, we aim to elaborate pathophysiology, examination and intervention of cardiac fibrosis after MI.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Nrf2 attenuates methamphetamine-induced myocardial injury by regulating oxidative stress and apoptosis in mice

OBJECTIVES

Methamphetamine (MA) abuse is a serious social problem worldwide. Cardiovascular complications were the second leading cause of death among MA abusers. We aimed to clarify the effects of MA on myocardial injury, oxidative stress, and apoptosis in myocardial cells and to explore the potential mechanism of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) in MA-induced oxidative stress and apoptosis.

METHODS

An acute cardiac toxicity model of MA was established by intraperitoneal injection of MA (2 mg/kg) for 5 days. Nrf2 activation (by sulforaphane (SFN) 1 h before MA injection) and Nrf2 gene knockout were performed to explore the regulatory effects of Nrf2 on cardiac toxicity.

RESULTS

The protein expressions of Nrf2 (p < .001) and heme oxygenase-1 (HO-1) were increased (p < .01), suggesting that MA activated the Nrf2/HO-1 pathway. In the MA group, cardiac injury score (p < .001) and cardiac troponin I (cTnI) protein expression increased (p < .01). Malondialdehyde (MDA) content increased (p < .001), superoxide dismutase (SOD) activity decreased (p < .05). Protein expressions of Caspase-3 (p < .001) and Bax (p < .001) increased, and Bcl-2 decreased (p < .001) as well. These changes were reversed by activation of Nrf2 but became more pronounced after Nrf2 knockout, suggested that the activation and knockout of Nrf2 attenuated and aggravated MA-induced myocardial injury, oxidative stress and apoptosis in myocardial cells, respectively.

CONCLUSIONS

MA administration induced myocardial injury, oxidative stress, and apoptosis in mice. Nrf2 attenuated MA-induced myocardial injury by regulating oxidative stress and apoptosis, thus playing a protective role.

Liquiritin Protects Against Cardiac Fibrosis After Myocardial Infarction by Inhibiting CCL5 Expression and the NF-κB Signaling Pathway

Purpose

Despite significant advances in interventional treatment, myocardial infarction (MI) and subsequent cardiac fibrosis remain major causes of high mortality worldwide. Liquiritin (LQ) is a flavonoid extract from licorice that possesses a variety of pharmacological properties. However, to our knowledge, the effects of LQ on myocardial fibrosis after MI have not been reported in detail. The aim of our research was to explore the potential role and mechanism of LQ in MI-induced myocardial damage.

Methods

The MI models were established by ligating the left anterior descending branch of the coronary artery. Next, rats were orally administered LQ once a day for 14 days. Biochemical assays, histopathological observations, ELISA, and Western blotting analyses were then conducted.

Results

LQ improved the heart appearance and ECG, decreased cardiac weight index and reduced levels of cardiac-specific markers such as CK, CK-MB, LDH, cTnI and BNP. Meanwhile, LQ reduced myocardial infarct size and improved hemodynamic parameters such as LVEDP, LVSP and ±dp/dt_max. Moreover, H&E staining showed that LQ attenuated the pathological damage caused by MI. Masson staining showed that LQ alleviated myocardial cell disorder and fibrosis while reducing collagen deposition. LQ also decreased the levels of oxidative stress and inflammation. Western blotting demonstrated that LQ significantly down-regulated the expressions of Collagen I, Collagen III, TGF-β1, MMP-9, α-SMA, CCL5, and p-NF-κB.

Conclusion

LQ protected against myocardial fibrosis following MI by improving cardiac function, and attenuating oxidative damage and inflammatory response, which may be associated with inhibition of CCL5 expression and the NF-κB pathway.

Molecular Mechanisms and Health Benefits of Ghrelin: A Narrative Review

Ghrelin, an endogenous brain-gut peptide, is secreted in large quantities, mainly from the stomach, in humans and rodents. It can perform the biological function of activating the growth hormone secretagogue receptor (GHSR). Since its discovery in 1999, ample research has focused on promoting its effects on the human appetite and pleasure-reward eating. Extensive, in-depth studies have shown that ghrelin is widely secreted and distributed in tissues. Its role in neurohumoral regulation, such as metabolic homeostasis, inflammation, cardiovascular regulation, anxiety and depression, and advanced cancer cachexia, has attracted increasing attention. However, the effects and regulatory mechanisms of ghrelin on obesity, gastrointestinal (GI) inflammation, cardiovascular disease, stress regulation, cachexia treatment, and the prognosis of advanced cancer have not been fully summarized. This review summarizes ghrelin's numerous effects in participating in a variety of biochemical pathways and the clinical significance of ghrelin in the regulation of the homeostasis of organisms. In addition, potential mechanisms are also introduced.

Flavonoid Extract from Propolis Provides Cardioprotection following Myocardial Infarction by Activating PPAR-γ

We have previously reported that flavonoid extract from propolis (FP) can improve cardiac function in rats following myocardial infarction (MI). However, the mechanisms responsible for the cardioprotective effects of FP have not been fully elucidated. In the current study, we explored whether FP can reduce inflammatory cytokines and attenuate sympathetic nerve system activity and antiendoplasmic reticulum (ER) stress and whether the cardioprotective effects are related to peroxisome proliferator-activated receptor gamma (PPAR-γ) activation. Sprague Dawley rats were randomly divided into six groups: Sham group received the surgical procedure but no artery was ligated; MI group received ligation of the left anterior descending (LAD) branch of the coronary artery; MI + FP group received FP (12.5 mg/kg/d, intragastrically) seven days prior to LAD ligation; FP group (Sham group + 12.5 mg/kg/d, intragastrically); MI + FP + GW9662 group received FP prior to LAD ligation with the addition of a specific PPAR-γ inhibitor (GW9662), 1 mg/kg/d, orally); and MI + GW9662 group received the PPAR-γ inhibitor and LAD ligation. The results demonstrated that the following inflammatory markers were significantly elevated following MI as compared with expression in sham animals: IL-1β, TNF-α, CRP; markers of sympathetic activation: plasma norepinephrine, epinephrine and GAP43, nerve growth factor, thyroid hormone; and ER stress response markers GRP78 and CHOP. Notably, the above changes were attenuated by FP, and GW9662 was able to alleviate the effect of FP. In conclusion, FP induces a cardioprotective effect following myocardial infarction by activating PPAR-γ, leading to less inflammation, cardiac sympathetic activity, and ER stress.

Up-regulation of Nrf2/HO-1 and inhibition of TGF-β1/Smad2/3 signaling axis by daphnetin alleviates transverse aortic constriction-induced cardiac remodeling in mice

Oxidative damage and accumulation of extracellular matrix (ECM) components play a crucial role in the adverse outcome of cardiac hypertrophy. Evidence suggests that nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) can modulate oxidative damage and adverse myocardial remodeling. Daphnetin (Daph) is a coumarin obtained from the plant genus Daphne species that exerts anti-oxidative and anti-inflammatory properties. Herein, we investigated the roles of Daph in transverse aortic constriction (TAC)-induced cardiac hypertrophy and fibrosis in mice. TAC-induced alterations in cardiac hypertrophy markers, histopathological changes, and cardiac function were markedly ameliorated by oral administration of Daph in mice. We found that Daph significantly reduced the reactive oxygen species (ROS) generation, increased the nuclear translocation of Nrf2, and consequently, reinstated the protein levels of NAD(P)H quinone dehydrogenase1 (NQO1), heme oxygenase-1 (HO-1), and other antioxidants in the heart. Besides, Daph significantly inhibited the TAC-induced accumulation of ECM components, including α-smooth muscle actin (α-SMA), collagen I, collagen III, and fibronectin, and interfered with the TGF-β1/Smad2/3 signaling axis. Further studies revealed that TAC-induced terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive nuclei and the protein levels of Bax/Bcl2 ratio and cleaved caspase 3 were substantially decreased by Daph treatment. We further characterized the effect of Daph on angiotensin II (Ang-II)-stimulated H9c2 cardiomyoblast cells and observed that Daph markedly decreased the Ang-II induced increase in cell size, production of ROS, and proteins associated with apoptosis and fibrosis. Mechanistically, Daph alone treatment enhanced the protein levels of Nrf2, NQO1, and HO-1 in H9c2 cells. The inhibition of this axis by Si-Nrf2 transfection abolished the protective effect of Daph in H9c2 cells. Taken together, Daph effectively counteracted the TAC-induced cardiac hypertrophy and fibrosis by improving the Nrf2/HO-1 axis and inhibiting the TGF-β1/Smad2/3 signaling axis.

Mechanism of Action of Flavonoids of Oxytropis falcata on the Alleviation of Myocardial Ischemia–Reperfusion Injury

Oxytropis falcata Bunge is a plant used in traditional Tibetan medicine, with reported anti-inflammatory and antioxidants effects and alleviation of myocardial ischemia reperfusion injury (MIRI). However, the underlying mechanism against MIRI and the phytochemical composition of O. falcata are vague. One fraction named OFF1 with anti-MIRI activity was obtained from O. falcata, and the chemical constituents were identified by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS). The potential targets and signaling pathways involved in the action of O. falcata against MIRI were predicted by network pharmacology analysis, and its molecular mechanism on MIRI was determined by in vitro assays. The results revealed that flavonoids are the dominant constituents of OFF1. A total of 92 flavonoids reported in O. falcata targeted 213 potential MIRI-associated factors, including tumor necrosis factor (TNF), prostaglandin-endoperoxide synthase 2 (PTGS2), and the NF-κB signaling pathway. The in vitro assay on H9c2 cardiomyocytes subjected to hypoxia/reoxygenation injury confirmed that the flavonoids in OFF1 reduced myocardial marker levels, apoptotic rate, and the inflammatory response triggered by oxidative stress. Moreover, OFF1 attenuated MIRI by downregulating the ROS-mediated JNK/p38MAPK/NF-κB pathway. Collectively, these findings provide novel insights into the molecular mechanism of O. falcata in alleviating MIRI, being a potential therapeutic candidate.

"Sibling" battle or harmony: crosstalk between nesfatin-1 and ghrelin

Ghrelin was first identified as an endogenous ligand of the growth hormone secretagogue receptor (GHSR) in 1999, with the function of stimulating the release of growth hormone (GH), while nesfatin-1 was identified in 2006. Both peptides are secreted by the same kind of endocrine cells, X/A-like cells in the stomach. Compared with ghrelin, nesfatin-1 exerts opposite effects on energy metabolism, glucose metabolism, gastrointestinal functions and regulation of blood pressure, but exerts similar effects on anti-inflammation and neuroprotection. Up to now, nesfatin-1 remains as an orphan ligand because its receptor has not been identified. Several studies have shown the effects of nesfatin-1 are dependent on the receptor of ghrelin. We herein compare the effects of nesfatin-1 and ghrelin in several aspects and explore the possibility of their interactions.