Decoding an organ regeneration switch by dissecting cardiac regeneration enhancers.

Heart regeneration in regeneration-competent organisms can be accomplished through the remodeling of gene expression in response to cardiac injury. This dynamic transcriptional response relies on the activities of tissue regeneration enhancer elements (TREEs); however, the mechanisms underlying TREEs are poorly understood. We dissected a cardiac regeneration enhancer in zebrafish to elucidate the mechanisms governing spatiotemporal gene expression during heart regeneration. Cardiac lepb regeneration enhancer (cLEN) exhibits dynamic, regeneration-dependent activity in the heart. We found that multiple injury-activated regulatory elements are distributed throughout the enhancer region. This analysis also revealed that cardiac regeneration enhancers are not only activated by injury, but surprisingly, they are also actively repressed in the absence of injury. Our data identified a short (22 bp) DNA element containing a key repressive element. Comparative analysis across Danio species indicated that the repressive element is conserved in closely related species. The repression mechanism is not operational during embryogenesis and emerges when the heart begins to mature. Incorporating both activation and repression components into the mechanism of tissue regeneration constitutes a new paradigm that might be extrapolated to other regeneration scenarios.

Immune Cells in Cardiac Injury Repair and Remodeling.

PURPOSE OF REVIEW: Immune cells are emerging as central cellular components of the heart which communicate with cardiac resident cells during homeostasis, cardiac injury, and remodeling. These findings are contributing to the development and continuous expansion of the new field of cardio-immunology. We review the most recent literature on this topic and discuss ongoing and future efforts to advance this field forward. RECENT FINDINGS: Cell-fate mapping, strategy depleting, and reconstituting immune cells in pre-clinical models of cardiac disease, combined with the investigation of the human heart at the single cell level, are contributing immensely to our understanding of the complex intercellular communication between immune and non-immune cells in the heart. While the acute immune response is necessary to initiate inflammation and tissue repair post injury, it becomes detrimental when sustained over time and contributes to adverse cardiac remodeling and pathology. Understanding the specific functions of immune cells in the context of the cardiac environment will provide new opportunities for immunomodulation to induce or tune down inflammation as needed in heart disease.

Molecular mechanisms mediate roflumilast protective effect against isoprenaline-induced myocardial injury.

BACKGROUND: Myocardial necrosis is one of the most common cardiac and pathological diseases. Unfortunately, using the available medical treatment is not sufficient to rescue the myocardium. So that, we aimed in our model to study the possible cardioprotective effect of roflumilast (ROF) in an experimental model of induced myocardial injury using a toxic dose of isoprenaline (ISO) and detecting the role of vascular endothelial growth factor/endothelial nitric oxide synthase (VEGF/eNOS) and cyclic guanosine monophosphate/cyclic adenosine monophosphate/ sirtuin1 (cGMP/cAMP/SIRT1) signaling cascade. MATERIALS AND METHODS: Animals were divided into five groups; control, ISO given group (150 mg/kg) i.p. on the 4th and 5th day, 3 ROF co-administered groups in different doses (0.25, 0.5, 1 mg/kg/day) for 5 days. RESULTS: Our data revealed that ISO could induce cardiac toxicity as manifested by significant increases in troponin I, creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), malondialdehyde (MDA), tumor necrosis factor alpha (TNFα), and cleaved caspase-3 with toxic histopathological changes. Meanwhile, there were significant decreases in reduced glutathione (GSH), total antioxidant capacity (TAC), VEGF, eNOS, cGMP, cAMP and SIRT1. However, co-administration of ROF showed significant improvement and normalization of ISO induced cardiac damage. CONCLUSION: We concluded that ROF successfully reduced ISO induced myocardial injury and this could be attributed to modulation of PDE4, VEGF/eNOS and cGMP/cAMP/SIRT1 signaling pathways with antioxidant, anti-inflammatory, and anti-apoptotic properties.

Berberine Alleviates Doxorubicin-Induced Myocardial Injury and Fibrosis by Eliminating Oxidative Stress and Mitochondrial Damage via Promoting Nrf-2 Pathway Activation.

Doxorubicin (DOX)-related cardiotoxicity has been recognized as a serious complication of cancer chemotherapy. Effective targeted strategies for myocardial protection in addition to DOX treatment are urgently needed. The purpose of this paper was to determine the therapeutic effect of berberine (Ber) on DOX-triggered cardiomyopathy and explore the underlying mechanism. Our data showed that Ber markedly prevented cardiac diastolic dysfunction and fibrosis, reduced cardiac malondialdehyde (MDA) level and increased antioxidant superoxide dismutase (SOD) activity in DOX-treated rats. Moreover, Ber effectively rescued the DOX-induced production of reactive oxygen species (ROS) and MDA, mitochondrial morphological damage and membrane potential loss in neonatal rat cardiac myocytes and fibroblasts. This effect was mediated by increases in the nuclear accumulation of nuclear erythroid factor 2-related factor 2 (Nrf2) and levels of heme oxygenase-1 (HO-1) and mitochondrial transcription factor A (TFAM). We also found that Ber suppressed the differentiation of cardiac fibroblasts (CFs) into myofibroblasts, as indicated by decreased expression of α-smooth muscle actin (α-SMA), collagen I and collagen III in DOX-treated CFs. Pretreatment with Ber inhibited ROS and MDA production and increased SOD activity and the mitochondrial membrane potential in DOX-challenged CFs. Further investigation indicated that the Nrf2 inhibitor trigonelline reversed the protective effect of Ber on both cardiomyocytes and CFs after DOX stimulation. Taken together, these findings demonstrated that Ber effectively alleviated DOX-induced oxidative stress and mitochondrial damage by activating the Nrf2-mediated pathway, thereby leading to the prevention of myocardial injury and fibrosis. The current study suggests that Ber is a potential therapeutic agent for DOX-induced cardiotoxicity that exerts its effects by activating Nrf2.

Neuropilin 1 mediates epicardial activation and revascularization in the regenerating zebrafish heart.

Unlike adult mammals, zebrafish can regenerate their heart. A key mechanism for regeneration is the activation of the epicardium, leading to the establishment of a supporting scaffold for new cardiomyocytes, angiogenesis and cytokine secretion. Neuropilins are co-receptors that mediate signaling of kinase receptors for cytokines with crucial roles in zebrafish heart regeneration. We investigated the role of neuropilins in response to cardiac injury and heart regeneration. All four neuropilin isoforms (nrp1a, nrp1b, nrp2a and nrp2b) were upregulated by the activated epicardium and an nrp1a-knockout mutant showed a significant delay in heart regeneration and displayed persistent collagen deposition. The regenerating hearts of nrp1a mutants were less vascularized, and epicardial-derived cell migration and re-expression of the developmental gene wt1b was impaired. Moreover, cryoinjury-induced activation and migration of epicardial cells in heart explants were reduced in nrp1a mutants. These results identify a key role for Nrp1 in zebrafish heart regeneration, mediated through epicardial activation, migration and revascularization.

Rapid fall in circulating non-classical monocytes in ST elevation myocardial infarction patients correlates with cardiac injury.

Myocardial infarction leads to a rapid innate immune response that is ultimately required for repair of damaged heart tissue. We therefore examined circulating monocyte dynamics immediately after reperfusion of the culprit coronary vessel in STEMI patients to determine whether this correlated with level of cardiac injury. A mouse model of cardiac ischemia/reperfusion injury was subsequently used to establish the degree of monocyte margination to the coronary vasculature that could potentially contribute to the drop in circulating monocytes. We retrospectively analyzed blood samples from 51 STEMI patients to assess the number of non-classical (NC), classical, and intermediate monocytes immediately following primary percutaneous coronary intervention. Classical and intermediate monocytes showed minimal change. On the other hand, circulating numbers of NC monocytes fell by approximately 50% at 90 minutes post-reperfusion. This rapid decrease in NC monocytes was greatest in patients with the largest infarct size (P < .05) and correlated inversely with left ventricular function (r = 0.41, P = .04). The early fall in NC monocytes post-reperfusion was confirmed in a second prospective study of 13 STEMI patients. Furthermore, in a mouse cardiac ischemia model, there was significant monocyte adhesion to coronary vessel endothelium at 2 hours post-reperfusion pointing to a specific and rapid vessel margination response to cardiac injury. In conclusion, rapid depletion of NC monocytes from the circulation in STEMI patients following coronary artery reperfusion correlates with the level of acute cardiac injury and involves rapid margination to the coronary vasculature.

Pitx2 promotes heart repair by activating the antioxidant response after cardiac injury.

Myocardial infarction results in compromised myocardial function and heart failure owing to insufficient cardiomyocyte self-renewal. Unlike many vertebrates, mammalian hearts have only a transient neonatal renewal capacity. Reactivating primitive reparative ability in the mature mammalian heart requires knowledge of the mechanisms that promote early heart repair. By testing an established Hippo-deficient heart regeneration mouse model for factors that promote renewal, here we show that the expression of Pitx2 is induced in injured, Hippo-deficient ventricles. Pitx2-deficient neonatal mouse hearts failed to repair after apex resection, whereas adult mouse cardiomyocytes with Pitx2 gain-of-function efficiently regenerated after myocardial infarction. Genomic analyses indicated that Pitx2 activated genes encoding electron transport chain components and reactive oxygen species scavengers. A subset of Pitx2 target genes was cooperatively regulated with the Hippo pathway effector Yap. Furthermore, Nrf2, a regulator of the antioxidant response, directly regulated the expression and subcellular localization of Pitx2. Pitx2 mutant myocardium had increased levels of reactive oxygen species, while antioxidant supplementation suppressed the Pitx2 loss-of-function phenotype. These findings reveal a genetic pathway activated by tissue damage that is essential for cardiac repair.

Role of Cardiac Fibroblasts in Cardiac Injury and Repair.

PURPOSE OF REVIEW: The pathological remodeling of cardiac tissue after injury or disease leads to scar formation. Our knowledge of the role of nonmyocytes, especially fibroblasts, in cardiac injury and repair continues to increase with technological advances in both experimental and clinical studies. Here, we aim to elaborate on cardiac fibroblasts by describing their origins, dynamic cellular states after injury, and heterogeneity in order to understand their role in cardiac injury and repair. RECENT FINDINGS: With the improvement in genetic lineage tracing technologies and the capability to profile gene expression at the single-cell level, we are beginning to learn that manipulating a specific population of fibroblasts could mitigate severe cardiac fibrosis and promote cardiac repair after injury. Cardiac fibroblasts play an indispensable role in tissue homeostasis and in repair after injury. Activated fibroblasts or myofibroblasts have time-dependent impacts on cardiac fibrosis. Multiple signaling pathways are involved in modulating fibroblast states, resulting in the alteration of fibrosis. Modulating a specific population of cardiac fibroblasts may provide new opportunities for identifying novel treatment options for cardiac fibrosis.

Zebrafish heart regenerates after chemoptogenetic cardiomyocyte depletion.

BACKGROUND: Zebrafish can regenerate adult cardiac tissue following injuries from ventricular apex amputation, cryoinjury, and cardiomyocyte genetic ablation. Here, we characterize cardiac regeneration from cardiomyocyte chemoptogenetic ablation caused by localized near-infrared excited photosensitizer-mediated reactive oxygen species (ROS) generation. RESULTS: Exposure of transgenic adult zebrafish, Tg(myl7:fapdl5-cerulean), to di-iodinated derivative of the cell- permeable Malachite Green ester fluorogen (MG-2I) and whole-body illumination with 660 nm light resulted in cytotoxic damage to about 30% of cardiac tissue. After chemoptogenetic cardiomyocyte ablation, heart function was compromised, and macrophage infiltration was detected, but epicardial and endocardial activation response was much muted when compared to ventricular amputation. The spared cardiomyocytes underwent proliferation and restored the heart structure and function in 45-60 days after ablation. CONCLUSIONS: This cardiomyocyte ablation system did not appear to activate the epicardium and endocardium as is noted in other cardiac injury models. This approach represents a useful model to study specifically cardiomyocyte injury, proliferation and regeneration in the absence of whole organ activation. Moreover, this system can be adapted to ablate distinct cell populations in any organ system to study their function in regeneration.

Sirtuin 3 deficiency aggravates angiotensin II-induced hypertensive cardiac injury by the impairment of lymphangiogenesis.

Lymphangiogenesis is possibly capable of attenuating hypertension-induced cardiac injury. Sirtuin 3 (SIRT3) is an effective mitochondrial deacetylase that has the potential to modulate this process; however, its role in hypertension-induced cardiac lymphangiogenesis to date has not been investigated. Our experiments were performed on 8-week-old wild-type (WT), SIRT3 knockout (SIRT3-KO) and SIRT3 overexpression (SIRT3-LV) mice infused with angiotensin II (Ang II) (1000 ng/kg per minute) or saline for 28 days. After Ang II infusion, SIRT3-KO mice developed a more severe cardiac remodelling, less lymphatic capillaries and lower expression of lymphatic marker when compared to wild-type mice. In comparison, SIRT3-LV restored lymphangiogenesis and attenuated cardiac injury. Furthermore, lymphatic endothelial cells (LECs) exposed to Ang II in vitro exhibited decreased migration and proliferation. Silencing SIRT3 induced functional decrease in LECs, while SIRT3 overexpression LECs facilitated. Moreover, SIRT3 may up-regulate lymphangiogenesis by affecting vascular endothelial growth factor receptor 3 (VEGFR3) and ERK pathway. These findings suggest that SIRT3 could promote lymphangiogenesis and attenuate hypertensive cardiac injury.

The role of adrenergic and muscarinic receptors in stress-induced cardiac injury.

Takotsubo syndrome (TS) is a rare but dangerous disease that can be fatal. The pathogenesis of TS is not well understood because there is no animal model of TS that fully mimics TS. It has now been documented that stress exposure (24 h) of rats induced the state which is similar TS in human: contracture damage of myofibrils, elevation of the serum creatine kinase MB level, increased 99mTc-pyrophosphate (99mTc-PYP) accumulation in the heart, QTc interval prolongation, and contractility dysfunction of the heart. Immobilization stress resulted in an increase in coronary blood flow. Emotional stress increased the serum catecholamine level. Blockade of ß1-adrenergic receptor (AR) prevented stress-induced cardiac injury (SICI). Blockade of ß2-AR aggravated stress-induced cardiac injury. Stimulation of ß2-AR increased cardiac tolerance to stress. Inhibition of ß3-AR, α1-AR had no effect on SICI. Blockade of peripheral muscarinic receptors or α2-AR aggravated SICI. Pretreatment with the selective ß1-AR antagonist atenolol attenuates stress-induced cardiac contractility dysfunction, but recovery of cardiac contractility is not complete. There is indirect evidence that circulating catecholamines play an important role in SICI. Consequently, the activation of ß1-AR plays a significant role in SICI. However, there are other receptors which are also involved in SICI and require further investigation.

Exacerbation of Coagulation and Cardiac Injury in Rats with Cisplatin-Induced Nephrotoxicity Following Intratracheal Instillation of Cerium Oxide Nanoparticles.

BACKGROUND/AIMS: Exposure to particulate air pollution is associated with increased cardiovascular morbidity and mortality. These effects are particularly aggravated in patients with pre-existing kidney diseases. Cerium oxide nanoparticles (CNPs), used as diesel fuel additives, are emitted in vehicle exhaust and affect humans when inhaled. However, thrombotic and cardiac injury resulting from pulmonary exposure to CNPs in experimental acute kidney injury (AKI) is not fully understood. The objective of the present study was to evaluate the thrombotic and cardiac injury effects of CNPs in a rat model of AKI. METHODS: AKI was induced in rats by a single intraperitoneal injection of cisplatin (CDDP, 6 mg/kg). Six days after injection, rats were intratracheally (i.t.) instilled with either CNPs (1 mg/kg) or saline (control), and various cardiovascular variables and markers of inflammation, oxidative stress and DNA injury were assessed by enzyme linked immunosorbent assay, colorimetric assay, single-cell gel electrophoresis assay and immunohistochemistry, the following day. RESULTS: Compared with individual CDDP or CNPs treatments, the combined CDDP + CNPs treatment elevated significantly the coagulation function, relative heart weight, and troponin I, lactate dehydrogenase, interleukin-6 (IL-6), tumor necrosis factor α (TNFα), and total nitric oxide levels in the plasma. In heart homogenates, the combination of CDDP and CNPs induced a significant increase in IL-6, TNFα, catalase, and glutathione. Furthermore, significantly more DNA damage was observed in this group than in the CDDP or CNPs groups. Immunohistochemical analysis of the heart revealed that expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) and glutathione peroxidase by cardiac myocytes and endothelial cells was increased in the CDDP + CNPs group more than in either CDDP or CNPs group. CONCLUSION: I.t. administration of CNPs in rats with AKI exacerbated systemic inflammation, oxidative stress, and coagulation events. It also aggravated cardiac inflammation, DNA damage, and Nrf2 expression.

Resolvin D1 and E1 promote resolution of inflammation in rat cardiac fibroblast in vitro.

Cardiac fibroblasts (CFs) have a key role in the inflammatory response after cardiac injury and are necessary for wound healing. Resolvins are potent agonists that control the duration and magnitude of inflammation. They decrease mediators of pro-inflammatory expression, reduce neutrophil migration to inflammation sites, promote the removal of microbes and apoptotic cells, and reduce exudate. However, whether resolvins can prevent pro-inflammatory-dependent effects in CFs is unknown. Thus, the present work was addressed to study whether resolvin D1 and E1 (RvD1 and RvE1) can prevent pro-inflammatory effects on CFs after lipopolysaccharide (LPS) challenge. For this, CFs were stimulated with LPS, in the presence or absence of RvD1 or RvE1, to analyze its effects on intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), monocyte adhesion and the cytokine levels of tumor necrosis factor alpha (TNF-α), interleukin-6(IL-6), interleukin-1beta (IL-1ß), monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10). Our results showed that CFs are expressing ALX/FPR2 and ChemR23, RvD1 and RvE1 receptors, respectively. RvD1 and RvE1 prevent the increase of ICAM-1 and VCAM-1 protein levels and the adhesion of spleen mononuclear cells to CFs induced by LPS. Finally, RvD1, but not RvE1, prevents the LPS-induced increase of IL-6, MCP-1, TNF-α, and IL-10. In conclusion, our findings provide evidence that in CFs, RvD1 and RvE1 might actively participate in the prevention of inflammatory response triggered by LPS.

Rutin treats myocardial damage caused by pirarubicin via regulating miR-22-5p-regulated RAP1/ERK signaling pathway.

Our experiments have previously demonstrated that rutin (RUT) can improve myocardial damage caused by pirarubicin (THP). However, the underlying molecular mechanisms remain uncertain. In this study, we developed an microRNA (miRNA) chip by replicating the rat model of THP-induced myocardial injury and identified miR-22-5p and the RAP1-member of RAS oncogene family/extracellular regulated protein kinases (RAP1/ERK) signaling pathway as an object of study. Also, in vivo experiments demonstrated that THP caused abnormal changes in the electrocardiogram, cardiac function, and histomorphology in rats (P < .01). THP also reduces the expression of miR-22-5p (P < .01) and increases the levels of RAP1/ERK signaling pathway-related proteins (P < .01, P < .05). RUT significantly improved THP-induced myocardial damage (P < .01), increased the expression of miR-22-5p (P < .01), and decreased the levels of RAP1/ERK signaling pathway-related proteins (P < .01, P < .05). In vitro studies confirmed that Rap1a is one of the target genes of miR-22-5p. miR-22-5p overexpression in cardiomyocytes can affect the RAP1/ERK pathway and reduce reactive oxygen species production and cardiomyocyte apoptosis caused by THP (P < .01), which is consistent with the effect of RUT. Our results indicate that RUT treats THP-induced myocardial damage, which may be achieved by upregulating miR-22-5p, causing changes in its target gene Rap1a and the RAP1/ERK pathway.

Cardiac impact of high-frequency irreversible electroporation using an asymmetrical waveform on liver in vivo.

BACKGROUND: High-Frequency Irreversible Electroporation (H-FIRE) is a novel technology for non-thermal ablation. Different from Irreversible electroporation (IRE), H-FIRE delivers bipolar electrical pulses without muscle contraction and does not cause electrolysis. Currently, little is known regarding the cardiac safety during the administration of H-FIRE on liver. The aim of this study was to evaluate the changes of electrocardiogram (ECG) and biomarkers of cardiac damage during asymmetrical waveform of H-FIRE therapy in vivo. METHODS: The swines (n = 7) in IRE group, which used 100 pulses (2200 V, 100-100 µs configuration), were administrated with muscle relaxant under anesthesia. In the absence of muscle relaxant, 7 swines in H-FIRE group were performed with 2400 pulses (3000 V, 5-3-3-5 µs configuration). Midazolam (0.5 mg/kg) and xylazine hydrochloride (20 mg/kg) were given to induce sedation, followed by Isoflurane (2.5%, 100% oxygen, 3 L/min) to maintain sedation in all the swines. Limb lead ECG recordings were analyzed by two electrophysiologists to judge the arrhythmia. Cardiac and liver tissue was examined by pathology technique. RESULTS: The ablation zones were larger in H-FIRE than IRE. Both IRE and H-FIRE did not affect the autonomous cardiac rhythm. Even when the electrical signal of IRE and H-FIRE fell on ventricular vulnerable period. Moreover, cTnI in IRE group showed an increase in 4 h after ablation, and decreased to baseline 72 h after ablation. However, cTnI showed no significant change during the administration of H-FIRE. CONCLUSIONS: The study suggests an asymmetrical waveform for H-FIRE is a promising measure for liver ablation. The results were based on normal liver and the swines without potential cardiac diseases. With the limitations of these facts, asymmetrical waveform for H-FIRE of liver tissue seems relatively safe without major cardiac complications. The safety of asymmetrical waveform for H-FIRE needs to evaluate in future.

Over time relationship between platelet reactivity, myocardial injury and mortality in patients with SARS-CoV-2-associated respiratory failure.

The aim of this study (NCT04343053) is to investigate the relationship between platelet activation, myocardial injury, and mortality in patients affected by Coronavirus disease 2019 (COVID-19). Fifty-four patients with respiratory failure due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were enrolled as cases. Eleven patients with the same clinical presentation, but negative for SARS-CoV-2 infection, were included as controls. Blood samples were collected at three different time points (inclusion [T1], after 7 ± 2 days [T2] and 14 ± 2 days [T3]). Platelet aggregation by light transmittance aggregometry and the circulating levels of soluble CD40 ligand (sCD40L) and P-selectin were measured. Platelet biomarkers did not differ between cases and controls, except for sCD40L which was higher in COVID-19 patients (p = .003). In COVID-19 patients, P-selectin and sCD40L levels decreased from T1 to T3 and were higher in cases requiring admission to intensive care unit (p = .004 and p = .008, respectively). Patients with myocardial injury (37%), as well as those who died (30%), had higher values of all biomarkers of platelet activation (p < .05 for all). Myocardial injury was an independent predictor of mortality. In COVID-19 patients admitted to hospital for respiratory failure, heightened platelet activation is associated with severity of illness, myocardial injury, and mortality.ClinicalTrials.gov number: NCT04343053.

iASPP protects the heart from ischemia injury by inhibiting p53 expression and cardiomyocyte apoptosis.

Currently, there remains a great need to elucidate the molecular mechanism of acute myocardial infarction in order to facilitate the development of novel therapy. Inhibitor of apoptosis-stimulating protein of p53 (iASPP) is a member of the ASPP family proteins and an evolutionarily preserved inhibitor of p53 that is involved in many cellular processes, including apoptosis of cancer cells. The purpose of this study was to investigate the possible role of iASPP in acute myocardial infarction. The protein level of iASPP was markedly reduced in the ischemic hearts in vivo and hydrogen peroxide-exposed cardiomyocytes in vitro. Overexpression of iASPP reduced the infarct size and cardiomyocyte apoptosis of mice subjected to 24 h of coronary artery ligation. Echocardiography showed that cardiac function was improved as indicated by the increase in ejection fraction and fractional shortening. In contrast, knockdown of iASPP exacerbated cardiac injury as manifested by impaired cardiac function, increased infarct size, and apoptosis rate. Mechanistically, overexpression of iASPP inhibited, while knockdown of iASPP increased the expressions of p53 and Bax, the key regulators of apoptosis. Taken together, our results suggested that iASPP is an important regulator of cardiomyocyte apoptosis, which represents a potential target in the therapy of myocardial infarction.

Longitudinal correlation of biomarkers of cardiac injury, inflammation, and coagulation to outcome in hospitalized COVID-19 patients.

BACKGROUND: Cardiac injury, as measured by troponin elevation, has been reported among hospitalized coronavirus disease 2019 (COVID-19) patients and portends a poor prognosis. However, how the dynamics of troponin elevation interplay with inflammation and coagulation biomarkers over time is unknown. We assessed longitudinal follow-up of cardiac injury, inflammation and coagulation markers in relation to disease severity and outcome. METHODS: We retrospectively assessed 2068 patients with laboratory-confirmed COVID-19 between January 29 and April 1, 2020 at Tongji Hospital in Wuhan, China. We defined cardiac injury as an increase in high sensitivity cardiac troponin-I (hs-cTnI) above the 99th of the upper reference limit. We explored the dynamics of elevation in hs-cTnI and the relationship with inflammation (interleukin [IL]-6, IL-8, IL-10, IL-2 receptor, tumor necrosis factor-α, C-reactive protein) and coagulation (d-dimer, fibrinogen, international normalized ratio) markers in non-critically ill versus critically ill patients longitudinally and further correlated these markers to survivors and non-survivors. RESULTS: Median age was 63 years (first to third quartile 51-70 years), 51.4% of whom were women. When compared to non-critically ill patients (N = 1592, 77.0%), critically ill (defined as requiring mechanical ventilation, in shock or multiorgan failure) patients (N = 476, 23.0%), had more frequent cardiac injury on admission (30.3% vs. 2.3%, p < 0.001), with increased mortality during hospitalization (38.4% vs. 0%, p < 0.001). Among critically ill patients, non-survivors (N = 183) had a continuous increase in hs-cTnI levels during hospitalization, while survivors (N = 293) showed a decrease in hs-cTnI level between day 4 and 7 after admission. Specifically, cardiac injury is an independent marker of mortality among critically ill patients at admission, day 4-7 and 8-14. Consistent positive correlations between hs-cTnI and interleukin (IL)-6 on admission (r = 0.59), day 4-7 (r = 0.66) and day 8-14 (r = 0.61; all p < 0.001) and d-dimer (at the same timepoints r = 0.54; 0.65; 0.61, all p < 0.001) were observed. A similar behavior was observed between hs-cTnI and most of other biomarkers of inflammation and coagulation. CONCLUSIONS: Cardiac injury commonly occurs in critically ill COVID-19 patients, with increased levels of hs-cTnI beyond day 3 since admission portending a poor prognosis. A consistent positive correlation of hs-cTnI with IL-6 and d-dimer at several timepoints along hospitalization could suggest nonspecific cytokine-mediated cardiotoxicity.

TRPV1 activation mitigates hypoxic injury in mouse cardiomyocytes by inducing autophagy through the AMPK signaling pathway.

Autophagy is a highly conserved self-protection mechanism that plays a crucial role in cardiovascular diseases. Cardiomyocyte hypoxic injury promotes oxidative stress and pathological alterations in the heart, although the interplay between these effects remains elusive. The transient receptor potential vanilloid 1 (TRPV1) ion channel is a nonselective cation channel that is activated in response to a variety of exogenous and endogenous physical and chemical stimuli. Here, we investigated the effects and mechanisms of action of TRPV1 on autophagy in hypoxic cardiomyocytes. In this study, primary cardiomyocytes isolated from C57 mice were subjected to hypoxic stress, and their expression of TRPV1 and adenosine 5'-monophosphate-activated protein kinase (AMPK) was regulated. The autophagy flux was assessed by Western blotting and immunofluorescence staining, and the cell viability was determined through Cell counting kit-8 assay and Lactate dehydrogenase assays. In addition, the calcium influx after the upregulation of TRPV1 expression in cardiomyocytes was examined. The results showed that the number of autophagosomes in cardiomyocytes was higher under hypoxic stress and that the blockade of autophagy flux aggravated hypoxic damage to cardiomyocytes. Moreover, the expression of TRPV1 was induced under hypoxic stress, and its upregulation by capsaicin improved the autophagy flux and protected cardiomyocytes from hypoxic damage, whereas the silencing of TRPV1 significantly attenuated autophagy. Our observations also revealed that AMPK signaling was activated and involved in TRPV1-induced autophagy in cardiomyocytes under hypoxic stress. Overall, this study demonstrates that TRPV1 activation mitigates hypoxic injury in cardiomyocytes by improving autophagy flux through the AMPK signaling pathway and highlights TRPV1 as a novel therapeutic target for the treatment of hypoxic cardiac disease.

LncRNA H19 ameliorates myocardial infarction-induced myocardial injury and maladaptive cardiac remodelling by regulating KDM3A.

Myocardial infarction (MI) remains the leading cause of morbidity and mortality worldwide, and novel therapeutic targets still need to be investigated to alleviate myocardial injury and the ensuing maladaptive cardiac remodelling. Accumulating studies have indicated that lncRNA H19 might exert a crucial regulatory effect on cardiovascular disease. In this study, we aimed to explore the biological function and molecular mechanism of H19 in MI. To investigate the biological functions of H19, miRNA-22-3p and KDM3A, gain- and loss-of-function experiments were performed. In addition, bioinformatics analysis, dual-luciferase reporter assays, RNA immunoprecipitation (RIP) assays, RNA pull-down assays, quantitative RT-PCR and Western blot analyses as well as rescue experiments were conducted to reveal an underlying competitive endogenous RNA (ceRNA) mechanism. We found that H19 was significantly down-regulated after MI. Functionally, enforced H19 expression dramatically reduced infarct size, improved cardiac performance and alleviated cardiac fibrosis by mitigating myocardial apoptosis and decreasing inflammation. However, H19 knockdown resulted in the opposite effects. Bioinformatics analysis and dual-luciferase assays revealed that, mechanistically, miR-22-3p was a direct target of H19, which was also confirmed by RIP and RNA pull-down assays in primary cardiomyocytes. In addition, bioinformatics analysis and dual-luciferase reporter assays also demonstrated that miRNA-22-3p directly targeted the KDM3A gene. Moreover, subsequent rescue experiments further verified that H19 regulated the expression of KDM3A to ameliorate MI-induced myocardial injury in a miR-22-3p-dependent manner. The present study revealed the critical role of the lncRNAH19/miR-22-3p/KDM3A pathway in MI. These findings suggest that H19 may act as a potential biomarker and therapeutic target for MI.