Cardiomyocyte Necrosis Research Articles

Secretome of Stressed Peripheral Blood Mononuclear Cells Alters Transcriptome Signature in Heart, Liver, and Spleen after an Experimental Acute Myocardial Infarction: An In Silico Analysis.

Simple SummaryAcute myocardial infarction is characterized by impaired coronary blood flow, which leads to cardiac ischemia and, ultimately, compromised heart function. Damage and cellular responses are not limited to the non-perfused area, but rather affect the entire heart, as well as distal organs, such as the liver and spleen. We found that the therapeutic secretome of stressed white blood cells improved short-term and long-term cardiac performance in a porcine infarction model. In order to unravel the molecular events governing secretome-mediated tissue regeneration, we performed transcriptional analyses of the non-perfused, transition, and perfused heart, as well as the liver and spleen 24 h after myocardial infarction. We observed a highly tissue-specific effect of the secretome and, except for the transition zone, a uniform downregulation of pro-inflammatory factors and pathways. Simultaneously, the secretome strongly promoted the expression of genes that are essential for heart function in the non-perfused area. In the liver and spleen, different metabolic processes were induced. Together, our data suggest several plausible mechanisms by which the secretome improves heart function after cardiac ischemia. Deepening our understanding of the molecular processes identified here might uncover further pharmacologic strategies aiming at delimiting adverse cardiac remodeling and sequelae after myocardial infarction.Acute myocardial infarction (AMI) is a result of cardiac non-perfusion and leads to cardiomyocyte necrosis, inflammation, and compromised cardiac performance. Here, we showed that the secretome of γ-irradiated peripheral blood mononuclear cells (PBMCsec) improved heart function in a porcine AMI model and displayed beneficial long- and short-term effects. As an AMI is known to strongly affect gene regulation of the ischemia non-affected heart muscle and distal organs, we employed a transcriptomics approach to further study the immediate molecular events orchestrated using the PBMCsec in myocardium, liver, and spleen 24 h post ischemia. In the infarcted area, the PBMCsec mainly induced genes that were essential for cardiomyocyte function and simultaneously downregulated pro-inflammatory genes. Interestingly, genes associated with pro-inflammatory processes were activated in the transition zone, while being downregulated in the remote zone. In the liver, we observed a pronounced inhibition of immune responses using the PBMCsec, while genes involved in urea and tricarboxylic cycles were induced. The spleen displayed elevated lipid metabolism and reduced immunological processes. Together, our study suggested several types of pharmacodynamics by which the PBMCsec conferred immediate cardioprotection. Furthermore, our data supported the assumption that an AMI significantly affects distal organs, suggesting that a holistic treatment of an AMI, as achieved by PBMCsec, might be highly beneficial.

Effects of Different Doses of Doxorubicin on H9C2 Cells

Objective: To study the effect of different doses of doxorubicin on H9C2 cells and to provide a reference for the clinical study of doxorubicin. Methods: Doxorubicin (1, 2, 4, 6, 10 ug/ml) was co-cultured with H9C2 cells for 6, 12 and 24 hours. The morphological changes of cells were observed, and the cell inhibition rates of different time and drug concentration were calculated. Results: Doxorubicin could inhibit the activity of cardiomyocytes in a dose-dependent manner from 1 to 10 ug/ml. Conclusion: A certain dose of doxorubicin has a toxic effect on cardiomyocytes and can cause cardiomyocyte necrosis and apoptosis.

Fatal Toxoplasma gondii myocarditis in an urban pet dog.

A 70-day-old Boxer dog from a household in Montevideo, Uruguay, died after presenting neurologic, respiratory, and gastrointestinal signs for 6days. Autopsy findings included lymphadenomegaly, ascites and hepatomegaly. Histopathology revealed severe widespread lymphohistiocytic and plasmacytic myocarditis with cardiomyocyte necrosis, mineralization and numerous intrasarcoplasmic protozoa immunoreactive with anti-Toxoplasma gondii antisera on immunohistochemistry. The protozoa were ultrastructurally confirmed as T. gondii by transmission electron microscopy. Other lesions included diffuse centrilobular hepatocellular necrosis, multifocal lymphohistiocytic portal hepatitis and interstitial nephritis. Other causes of myocarditis, including Neospora caninum, Trypanosoma cruzi, Sarcocystis neurona, canine distemper virus, and canine parvovirus were ruled out by immunohistochemistry. Toxoplasma gondii infections in dogs are usually subclinical; however, clinical disease with fatal outcome can occur. To our knowledge, this is the first report of fatal toxoplasmosis in a dog in Uruguay. This case raises awareness for dogs as sentinels and possible sources of human toxoplasmosis in urban settings in Uruguay.

68Ga FAPI PET/MRI in Cardiac Amyloidosis.

HomeRadiologyVol. 303, No. 1 PreviousNext Reviews and CommentaryFree AccessImages In Radiology68Ga FAPI PET/MRI in Cardiac AmyloidosisWei Guo, Haojun Chen Wei Guo, Haojun Chen Author AffiliationsFrom the Department of Nuclear Medicine and Minnan PET Center, Xiamen Cancer Center, First Affiliated Hospital of Xiamen University, Teaching Hospital of Fujian Medical University, 55 Zhenhai Road, Xiamen 361003, China.Address correspondence to H.C. (e-mail: [email protected]).Wei GuoHaojun Chen Published Online:Dec 21 2021https://doi.org/10.1148/radiol.211951MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In A 66-year-old woman presented with progressive dyspnea for 3 months. Cardiac MRI showed diffuse thickening of the left ventricle with global left ventricularle subendocardial delayed contrast material enhancement that was suggestive of cardiac amyloidosis (Figure, A). Serum free light-chain analysis showed an altered κ and λ ratio of 0.0036 (normal range, 0.26–1.65), with an increased proportion of λ light chains (2355 mg/L; normal range, 6–26 mg/L). Bone marrow biopsy results showed multiple myeloma. A research gallium 68 (68Ga)–conjugated fibroblast-activation protein inhibitor (FAPI) PET/CT examination was performed for staging of the multiple myeloma (ClinicalTrials.gov identifier: NCT04416165), which showed diffuse and inhomogeneous 68Ga FAPI uptake in the thickened left ventricle myocardium and tongue (Figure, B). Tongue biopsy results showed positive Congo red staining consistent with amyloid involvement. Thus, a diagnosis of cardiac and lingual amyloidosis secondary to multiple myeloma was made.Images in 66-year-old woman who presented with progressive dyspnea for 3 months. (A) Cardiac MRI scan in four-chamber view shows diffuse thickening of left ventricle with global subendocardial left ventricular late gadolinium enhancement (arrows), which is suggestive of cardiac amyloidosis. (B) Gallium 68 (68Ga)–conjugated fibroblast-activation protein inhibitor (FAPI) PET/CT scan, which is fused with previous cardiac MRI scans, shows intense 68Ga FAPI uptake (arrows) localized within thickened left ventricle myocardium.Download as PowerPointOpen in Image Viewer Multiple myeloma is the most common primary bone malignancy. The median age at diagnosis is 60–70 years. The incidence is higher in men than in women (7.1 per 100 000 vs 4.6 per 100 000, respectively). Light-chain amyloidosis occurs in 5%–10% of patients with multiple myeloma, and cardiac involvement is associated with worsened outcomes (1). Cardiac amyloidosis deposition leads to cardiomyocyte necrosis and interstitial fibrosis (2). 68Ga FAPI PET/MRI may be useful for imaging cardiac amyloidosis, as it shows both areas of fibrosis and inflammation.Disclosures of Conflicts of Interest: W.G. No relevant relationships. H.C. No relevant relationships.Supported by the National Natural Science Foundation of China (grant nos. 81801735 and 82071961).

Cardiac inflammation and microvascular procoagulant changes are decreased in second wave compared to first wave deceased COVID-19 patients

BackgroundCompelling evidence has shown cardiac involvement in COVID-19 patients. However, the overall majority of these studies use data obtained during the first wave of the pandemic, while recently differences have been reported in disease course and mortality between first- and second wave COVID-19 patients. The aim of this study was to analyze and compare cardiac pathology between first- and second wave COVID-19 patients. MethodsAutopsied hearts from first- (n = 15) and second wave (n = 10) COVID-19 patients and from 18 non-COVID-19 control patients were (immuno)histochemically analyzed. CD45+ leukocyte, CD68+ macrophage and CD3+ T lymphocyte infiltration, cardiomyocyte necrosis and microvascular thrombosis were quantified. In addition, the procoagulant factors Tissue Factor (TF), Factor VII (FVII), Factor XII (FXII), the anticoagulant protein Dipeptidyl Peptidase 4 (DPP4) and the advanced glycation end-product N(ε)-Carboxymethyllysine (CML), as markers of microvascular thrombogenicity and dysfunction, were quantified. ResultsCardiac inflammation was significantly decreased in second wave compared to first wave COVID-19 patients, predominantly related to a decrease in infiltrated lymphocytes and the occurrence of lymphocytic myocarditis. This was accompanied by significant decreases in cardiomyocyte injury and microvascular thrombosis. Moreover, microvascular deposits of FVII and CML were significantly lower in second wave compared to first wave COVID-19 patients. ConclusionsThese results show that in our cohort of fatal COVID-19 cases cardiac inflammation, cardiomyocyte injury and microvascular thrombogenicity were markedly decreased in second wave compared to first wave patients. This may reflect advances in COVID-19 treatment related to an increased use of steroids in the second COVID-19 wave.

COVID-19, the Pandemic of the Century and Its Impact on Cardiovascular Diseases.

COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection likely ranks among the deadliest diseases in human history. As with other coronaviruses, SARS-CoV-2 infection damages not only the lungs but also the heart and many other organs that express angiotensin-converting enzyme 2 (ACE2), a receptor for SARS-CoV-2. COVID-19 has upended lives worldwide. Dietary behaviors have been altered such that they favor metabolic and cardiovascular complications, while patients have avoided hospital visits because of limited resources and the fear of infection, thereby increasing out-hospital mortality due to delayed diagnosis and treatment. Clinical observations show that sex, age, and race all influence the risk for SARS-CoV-2 infection, as do hypertension, obesity, and pre-existing cardiovascular conditions. Many hospitalized COVID-19 patients suffer cardiac injury, acute coronary syndromes, or cardiac arrhythmia. SARS-CoV-2 infection may lead to cardiomyocyte apoptosis and necrosis, endothelial cell damage and dysfunction, oxidative stress and reactive oxygen species production, vasoconstriction, fibrotic and thrombotic protein expression, vascular permeability and microvascular dysfunction, heart inflammatory cell accumulation and activation, and a cytokine storm. Current data indicate that COVID-19 patients with cardiovascular diseases should not discontinue many existing cardiovascular therapies such as ACE inhibitors, angiotensin receptor blockers, steroids, aspirin, statins, and PCSK9 inhibitors. This review aims to furnish a framework relating to COVID-19 and cardiovascular pathophysiology.

Cellular pathophysiology of Friedreich's ataxia cardiomyopathy

Friedreich's ataxia (FRDA) is a hereditary neuromuscular disorder. Cardiomyopathy is the leading cause of premature death in FRDA. FRDA cardiomyopathy is a complex and progressive disease with no cure or treatment to slow its progression. At the cellular level, cardiomyocyte hypertrophy, apoptosis and fibrosis contribute to the cardiac pathology. However, the heart is composed of multiple cell types and several clinical studies have reported the involvement of cardiac non-myocytes such as vascular cells, autonomic neurons, and inflammatory cells in the pathogenesis of FRDA cardiomyopathy. In fact, several of the cardiac pathologies associated with FRDA including cardiomyocyte necrosis, fibrosis, and arrhythmia, could be contributed to by a diseased vasculature and autonomic dysfunction. Here, we review available evidence regarding the current understanding of cellular mechanisms for, and the involvement of, cardiac non-myocytes in the pathogenesis of FRDA cardiomyopathy.

Magnetic Resonance Texture Analysis in Myocardial Infarction.

Texture analysis (TA) is a newly arisen field that can detect the invisible MRI signal changes among image pixels. Myocardial infarction (MI) is cardiomyocyte necrosis caused by myocardial ischemia and hypoxia, becoming the primary cause of death and disability worldwide. In recent years, various TA studies have been performed in patients with MI and show a good clinical application prospect. This review briefly presents the main pathogenesis and pathophysiology of MI, introduces the overview and workflow of TA, and summarizes multiple magnetic resonance TA (MRTA) clinical applications in MI. We also discuss the facing challenges currently for clinical utilization and propose the prospect.

Pathomorphological changes in the organs of chickens infected spontaneously by the species Salmonella pullorum on private farms in Chernivtsi region

Commercial poultry production growth and the increase in the number of small farms specializing in raising broiler chickens, laying hens, quails, and other poultry contribute to the spread of infectious diseases. Non-compliance with the principles of biosafety during incubation and breeding results in mass deaths of poultry and, consequently, significant economic losses for farmers. Salmonellosis is one of the most dangerous anthropozoonotic diseases of poultry, which is most often registered in private farms. Age analysis of the poultry salmonellosis in the EU countries indicates the infection of adult laying hens most often, young poultry to a lesser extent, and chickens aged up to 10 days less frequently. Although the program for the prevention and elimination of poultry salmonellosis has been approved at the legislative level in Ukraine, monitoring studies are not carefully conducted. This is especially true for private homesteads and small farms, which greatly complicates the epizootiological situation in some regions of the country. The article describes the pathological and histological changes in the liver, heart, lungs, kidneys, and spleen. The changes were detected in chickens aged 10 and 14 days infected with microorganisms of the species Salmonella pullorum. Eggs for incubation were obtained from different family flocks, and incubation was performed in a single incubator. The initial clinical signs of the disease appeared in chickens aged 7 days and included diarrhea, increased water consumption, lameness, mass concentration of chickens near heat sources, nervous phenomena in the form of circle walking, and partial blindness in some cases. The pathological autopsy revealed hepatomegaly with sharp change in the organ colour, diapedetic hemorrhage under Glisson’s capsule, and diffuse miliary necrosis. Greyish-white nodular lesions of the lungs and heart, dystrophic changes in the kidneys, and deposition of uric acid salts in the ureters were also characteristic features. Diffuse coagulation necrosis, massive perivascular infiltration by heterophilic lymphocytes and stasis were observed in the liver. Changes in the heart were characterized by significant infiltration by mononuclear cells and heterophiles, which led to atrophy, necrosis, and replacement of cardiomyocytes by connective tissue cellular elements. Delymphatization and necrosis of the lymph nodes were pronounced in the spleen.

Development of injectable graphene oxide/laponite/gelatin hydrogel containing Wharton's jelly mesenchymal stem cells for treatment of oxidative stress-damaged cardiomyocytes

In the initial stage of myocardial infarction (MI), cardiomyocyte necrosis activates aninflammatory response and increases the reactive oxygen species (ROS) content. Graphene oxide (GO) possesses potential antioxidant properties and can provide the adequate mechanical support for cell growth. The clinical studies showed that direct injection of Wharton's jelly mesenchymal stem cells (WJ-MSCs) into infarcted areas of myocardium can reduce apoptosis and fibrosis. Gelatin is a natural polymer and can promote cell attachment. Nanoclay laponite with shear-thinning properties can be injected and gelled in-situ without chemical triggers. In the study, injectable GO/laponite/gelatin (GO-LG) hydrogel was developed and characterized. The results of cell viability showed that the optimal concentration of GO flasks (200 to 300 nm) to treat cells was 100 μg/ml. Addition of nanosized GO to the laponite/gelatin (LG) hydrogel could increase the mechanical strength and have both hemocompatibility and cytocompatibility. The release of GO from LG hydrogel could inhibit the H2O2-induced oxidative stress. The GO-LG hydrogel containing WJ-MSCs could decrease inflammation and apoptosis level and increase the cell viability of cardiomyocytes under oxidative stress. We believe that utilizing this newly developed GO-LG hydrogel containing WJ-MSCs may have potential applications in the future for treatment of MI.

Protective effect of TAK242 blocking Toll-like receptor 4 pathway on septic myocardial injury and cardiac dysfunction

To investigate the role of Toll-like receptor 4 (TLR4) pathway on myocardial injury and cardiac dysfunction in septic rats. According to the random number table, 18 male Sprague-Dawley (SD) rats were divided into control group, lipopolysaccharide (LPS) group and TLR4 specific inhibitor TAK242 pretreatment group (TAK242+LPS group) with 6 rats in each group. The rat model of septic cardiac dysfunction was induced by intraperitoneal injection of LPS 15 mg/kg, and the control group was given the same amount of normal saline. The TAK242+LPS group was intraperitoneally given injection of TAK242 [it was injected intraperitoneally at a dose of 3 mg/kg and dissolved in 10% dimethyl sulfoxide (DMSO) and 90% corn oil according to the concentration of 0.2 g/L] 3 hours before LPS stimulation. The control group and LPS group were given the same amount of 10% DMSO and 90% corn oil. The cardiac function of rats in each group was examined by Doppler echocardiography 14 hours after injection of LPS. The blood of abdominal aorta was taken and the level of serum troponin (cTn) was measured by enzyme linked immunosorbent assay (ELISA). Myocardial tissue was harvested for hematoxylin-eosin (HE) staining, and the morphological changes of myocardial tissue were observed under light microscope. The mRNA expressions of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in myocardial tissue were detected by real-time fluorescence quantitative polymerase chain reaction (qPCR). The protein expression of TLR4 in myocardial tissue was observed by immunohistochemical method. Western blotting was used to detect the levels of TLR4, nuclear factor-κB p65 (NF-κB p65) and its phosphorylation (p-NF-κB p65) in myocardial tissue. (1) The cardiac function and myocardial injury: Doppler echocardiography showed that the levels of left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) in the LPS group were significantly higher than those in the control group, while left ventricular ejection fraction (LVEF) and left ventricular shortened fraction (LVFS) were significantly lower than those in the control group. The degeneration, necrosis and inflammatory cell infiltration of cardiomyocytes were found with light microscope in the LPS group, and the levels of serum cTn were significantly higher than those in the control group, indicating that LPS-induced sepsis could cause cardiac dysfunction and myocardial injury. TAK242 blocking TLR4 pathway had a protective effect on cardiac function and myocardium during sepsis. LVEDV and LVESV in the TAK242+LPS group were significantly lower than those in the LPS group [LVEDV (μL): 71.25±21.16 vs. 118.01±11.89, LVESV (μL): 9.57±5.75 vs. 32.70±9.22, both P < 0.01]. LVEF and LVFS were significantly higher than those in the LPS group [LVEF: 0.868±0.075 vs. 0.722±0.095, LVFS: (59.88±8.46)% vs. (42.37±8.71)%, both P < 0.05]. Myocardial tissue injury was significantly reduced, and the serum cTn level was significantly lower than that in the LPS group (μg/L: 107.85±21.38 vs. 152.25±27.46, P < 0.05). (2) Inflammatory parameters: the results of qPCR, Western blotting and immunohistochemistry showed that the mRNA expressions of IL-6 and TNF-α, the expression of TLR4 protein and the p-NF-κB p65/NF-κB p65 ratio in the LPS group were significantly higher than those in the control group, indicating that LPS-induced sepsis could activate the inflammatory response mediated by TLR4/NF-κB pathway in the heart. However, blocking the TLR4 pathway by TAK242 could inhibit the TLR4/NF-κB pathway and reduce the myocardial inflammation in septic rats. The mRNA expressions of IL-6 and TNF-α, the expression of TLR4 protein and the p-NF-κB p65/NF-κB p65 ratio in the TAK242+LPS group were significantly lower than those in the LPS group [IL-6 mRNA (2-ΔΔCT): 10.44±3.30 vs. 107.50±29.48, TNF-α mRNA (2-ΔΔCT): 2.38±0.68 vs. 3.77±0.56, TLR4 protein (TLR4/GAPDH): 0.39±0.01 vs. 0.58±0.04, p-NF-κB p65/NF-κB p65 ratio: 1.21±0.11 vs. 2.10±0.18, all P < 0.05]. TAK242 can protect LPS-induced cardiac dysfunction and myocardial injury by blocking the TLR4 mediated inflammatory response.

Современный взгляд на патофизиологические аспекты развития хронической сердечной недостаточности на фоне ишемической болезни сердца

В руководстве Европейского общества кардиологов по сердечной недостаточности 2016 года был введен термин «сердечная недостаточность с промежуточной фракцией выброса» для обозначения пациентов с сердечной недостаточностью и незначительно сниженной фракцией выброса 40–49 %. Сегодня установлено, что около 20 % пациентов с сердечной недостаточностью попадают в эту категорию. Доказано, что ишемическая болезнь сердца является одним из ведущих факторов формирования и прогрессирования диастолического нарушения левого желудочка. Более чем у 90 % пациентов с ишемической болезнью сердца разной степени проявляется диастолическая дисфункция, в основе которой могут лежать нарушения активной релаксации и фибротические процессы в миокарде, которые возникают вследствие прогрессирующего атеросклеротического кардиосклероза или перенесенного острого инфаркта миокарда. В связи с этим актуальным является анализ последних данных о механизмах формирования миокардиального фиброза ишемического генеза и его роли в патогенезе сердечной недостаточности. Было доказано, что хроническое гипоксически-ишемическое повреждение миокарда сопровождается некрозом кардиомиоцитов, на месте которых развивается репаративный фиброз, при этом появившиеся коллагеновые волокна заполняют место кардиомиоцитов. В пограничной зоне между рубцом, который сформирован за счет репаративного фиброза, и зоной гибернированного миокарда, в меньшей степени в интактном миокарде, развивается реактивный фиброз (периваскулярный и интерстициальный). Его образование косвенно обусловлено перегрузкой давлением и перерастяжением волокон кардиомиоцитов. Миофибробласты экспрессируют сократительные белки, подобные актину гладких мышц, обеспечивающих механическое натяжение в ремоделированном матриксе, тем самым уменьшая зону рубца. В любом случае развитие фиброза во внеклеточном матриксе является неотъемлемой частью ремоделирования миокарда и требует продолжения исследований, направленных на решение проблемы участия всех механизмов в патогенезе хронической сердечной недостаточности на фоне ишемической болезни сердца в зависимости от ее типа.

Nox2-deficient Tregs improve heart transplant outcomes via their increased graft recruitment and enhanced potency.

Nox2 is a ROS-generating enzyme, deficiency of which increases suppression by Tregs in vitro and in an in vivo model of cardiac remodeling. As Tregs have emerged as a candidate therapy in autoimmunity and transplantation, we hypothesized that Nox2 deficiency in Tregs in recipient mice may improve outcomes in a heart transplant model. We generated a potentially novel B6129 mouse model with Treg-targeted Nox2 deletion (Nox2fl/flFoxP3Cre+ mice) and transplanted with hearts from CB6F1 donors. As compared with those of littermate controls, Nox2fl/flFoxP3Cre+ mice had lower plasma levels of alloantibodies and troponin-I, reduced levels of IFN-γ in heart allograft homogenates, and diminished cardiomyocyte necrosis and allograft fibrosis. Single-cell analyses of allografts revealed higher absolute numbers of Tregs and lower CD8+ T cell infiltration in Nox2-deficient recipients compared with Nox2-replete mice. Mechanistically, in addition to a greater suppression of CD8+CD25– T effector cell proliferation and IFN-γ production, Nox2-deficient Tregs expressed higher levels of CCR4 and CCR8, driving cell migration to allografts; this was associated with increased expression of miR-214-3p. These data indicate that Nox2 deletion in Tregs enhances their suppressive ability and migration to heart allografts. Therefore, Nox2 inhibition in Tregs may be a useful approach to improve their therapeutic efficacy.

Catecholamine Surges Cause Cardiomyocyte Necroptosis via a RIPK1-RIPK3-Dependent Pathway in Mice.

Background: Catecholamine surges and resultant excessive β-adrenergic stimulation occur in a broad spectrum of diseases. Excessive β-adrenergic stimulation causes cardiomyocyte necrosis, but the underlying mechanism remains obscure. Necroptosis, a major form of regulated necrosis mediated by RIPK3-centered pathways, is implicated in heart failure; however, it remains unknown whether excessive β-adrenergic stimulation-induced cardiac injury involves necroptosis. Hence, we conducted the present study to address these critical gaps.Methods and Results: Two consecutive daily injections of isoproterenol (ISO; 85 mg/kg, s.c.) or saline were administered to adult mixed-sex mice. At 24 h after the second ISO injection, cardiac area with Evans blue dye (EBD) uptake and myocardial protein levels of CD45, RIPK1, Ser166-phosphorylated RIPK1, RIPK3, and Ser345-phosphorylated MLKL (p-MLKL) were significantly greater, while Ser321-phosphorylated RIPK1 was significantly lower, in the ISO-treated than in saline-treated wild-type (WT) mice. The ISO-induced increase of EBD uptake was markedly less in RIPK3−/− mice compared with WT mice (p = 0.016). Pretreatment with the RIPK1-selective inhibitor necrostatin-1 diminished ISO-induced increases in RIPK3 and p-MLKL in WT mice and significantly attenuated ISO-induced increases of EBD uptake in WT but not RIPK3−/− mice.Conclusions: A large proportion of cardiomyocyte necrosis induced by excessive β-adrenergic stimulation belongs to necroptosis and is mediated by a RIPK1–RIPK3-dependent pathway, identifying RIPK1 and RIPK3 as potential therapeutic targets for catecholamine surges.

Abstract MP201: PKA Regulatory Subunit 1α As A Novel Necrosis Suppressor In Myocardial Ischemia/Reperfusion

Reperfusion therapy, the standard treatment for acute myocardial infarction, can trigger necrotic death of cardiomyocytes and provoke ischemia/reperfusion (I/R) injury. However, signaling pathways that regulate cardiomyocyte necrosis remain largely unknown. Our recent genome-wide RNAi screen has identified a potential necrosis suppressor gene PRKAR1A , which encodes PKA regulatory subunit 1α (R1α). R1α is primarily known for regulating PKA activity based on cAMP level, by restraining PKA catalytic subunits in the absence of cAMP. Here, we showed that disruption of R1α augmented cardiomyocyte necrosis in vitro and in vivo , resulting in exaggerated myocardial I/R injury and contractile dysfunction. Mechanistically, R1α loss repressed the Nrf2 antioxidant transcription factor and aggravated oxidative stress following I/R. Degradation of the endogenous Nrf2 inhibitor Keap1 through p62-dependent selective autophagy was blocked by R1α depletion. Phosphorylation of p62 at Ser349 by mammalian target of rapamycin complex 1 (mTORC1), a critical step in p62-Keap1 interaction, was induced by I/R, but diminished by R1α loss. Activation of PKA by forskolin or isoproterenol almost completely abolished hydrogen peroxide-induced p62 phosphorylation. In conclusion, R1α loss induces unrestrained PKA activation and impairs the mTORC1-p62-Keap1-Nrf2 antioxidant defense system, leading to aggravated oxidative stress, necrosis and myocardial I/R injury. Our findings uncover a novel role of PKA in oxidative stress and necrosis. Therefore, PKA signaling may be exploited to develop new cardioprotective therapies.

Intravenous Injection of Coronavirus Disease 2019 (COVID-19) mRNA Vaccine Can Induce Acute Myopericarditis in Mouse Model.

BackgroundPost-vaccination myopericarditis is reported after immunization with coronavirus disease 2019 (COVID-19) messenger RNA (mRNA) vaccines. The effect of inadvertent intravenous injection of this vaccine on the heart is unknown.MethodsWe compared the clinical manifestations, histopathological changes, tissue mRNA expression, and serum levels of cytokine/chemokine and troponin in Balb/c mice at different time points after intravenous (IV) or intramuscular (IM) vaccine injection with normal saline (NS) control.ResultsAlthough significant weight loss and higher serum cytokine/chemokine levels were found in IM group at 1–2 days post-injection (dpi), only IV group developed histopathological changes of myopericarditis as evidenced by cardiomyocyte degeneration, apoptosis, and necrosis with adjacent inflammatory cell infiltration and calcific deposits on visceral pericardium, although evidence of coronary artery or other cardiac pathologies was absent. Serum troponin level was significantly higher in IV group. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike antigen expression by immunostaining was occasionally found in infiltrating immune cells of the heart or injection site, in cardiomyocytes and intracardiac vascular endothelial cells, but not skeletal myocytes. The histological changes of myopericarditis after the first IV-priming dose persisted for 2 weeks and were markedly aggravated by a second IM- or IV-booster dose. Cardiac tissue mRNA expression of interleukin (IL)-1β, interferon (IFN)-β, IL-6, and tumor necrosis factor (TNF)-α increased significantly from 1 dpi to 2 dpi in the IV group but not the IM group, compatible with presence of myopericarditis in the IV group. Ballooning degeneration of hepatocytes was consistently found in the IV group. All other organs appeared normal.ConclusionsThis study provided in vivo evidence that inadvertent intravenous injection of COVID-19 mRNA vaccines may induce myopericarditis. Brief withdrawal of syringe plunger to exclude blood aspiration may be one possible way to reduce such risk.

Disorders in blood circulation as a probable cause of death in dogs infected with Babesia canis

IntroductionThe purpose of the study was to investigate post-mortem changes in dogs infected with Babesia canis and to establish the probable cause of death of the affected animals.Material and MethodsCadavers of six dogs that did not survive babesiosis were collected. Necropsies were performed and samples of various organs were collected for histological examination.ResultsNecropsies and histological examinations revealed congestion and oedemata in various organs. Most of the dogs had ascites, hydrothorax or hydropericardium, pulmonary oedema, pulmonary, renal, hepatic, and cerebral congestion, and necrosis of cardiomyocytes.ConclusionThese results suggested disorders in blood circulation as the most probable cause of death. However, the pulmonary inflammatory response and cerebral babesiosis observed in some of these dogs could also be considered possible causes of death. This study also showed a possible role for renal congestion in the development of renal hypoxia and azotaemia in canine babesiosis.

Discovery of β-Carboline Derivatives as a Highly Potent Cardioprotectant against Myocardial Ischemia-Reperfusion Injury.

Timely myocardial reperfusion salvages ischemic myocardium from infarction, whereas reperfusion itself induces cardiomyocyte death, which is called myocardial ischemia/reperfusion (MI/R) injury. Herein, β-carboline derivative 17c was designed and synthesized with obvious myocardial protective activity for the first time. Pretreatment of 17c effectively protected the cardiomyocyte H9c2 cells from H2O2-induced lactate dehydrogenase leakage and restored the endogenous antioxidants, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Besides, 17c effectively protected the mitochondria through decreasing the reactive oxygen species overproduction and enhancing the mitochondrial membrane potential. As a result, 17c significantly reduced the necrosis of cardiomyocytes in H2O2-induced oxidative stress, which was more potent than polydatin. In MI/R injury rats, 17c pretreatment obviously increased the levels of SOD and GSH-Px and inhibited the apoptosis of cardiomyocytes. Through this way, the size of myocardial infarction was significantly reduced after MI/R injury in vivo, better than that of polydatin, suggesting that 17c is a promising cardioprotectant for the prevention of MI/R injury.

Loss of PKA regulatory subunit 1α aggravates cardiomyocyte necrosis and myocardial ischemia/reperfusion injury

Reperfusion therapy, the standard treatment for acute myocardial infarction, can trigger necrotic death of cardiomyocytes and provoke ischemia/reperfusion (I/R) injury. However, signaling pathways that regulate cardiomyocyte necrosis remain largely unknown. Our recent genome-wide RNAi screen has identified a potential necrosis suppressor gene PRKAR1A, which encodes PKA regulatory subunit 1α (R1α). R1α is primarily known for regulating PKA activity by sequestering PKA catalytic subunits in the absence of cAMP. Here, we showed that depletion of R1α augmented cardiomyocyte necrosis in vitro and in vivo, resulting in exaggerated myocardial I/R injury and contractile dysfunction. Mechanistically, R1α loss downregulated the Nrf2 antioxidant transcription factor and aggravated oxidative stress following I/R. Degradation of the endogenous Nrf2 inhibitor Keap1 through p62-dependent selective autophagy was blocked by R1α depletion. Phosphorylation of p62 at Ser349 by mammalian target of rapamycin complex 1 (mTORC1), a critical step in p62-Keap1 interaction, was induced by I/R, but diminished by R1α loss. Activation of PKA by forskolin or isoproterenol almost completely abolished hydrogen-peroxide-induced p62 phosphorylation. In conclusion, R1α loss induces unrestrained PKA activation and impairs the mTORC1-p62-Keap1-Nrf2 antioxidant defense system, leading to aggravated oxidative stress, necrosis, and myocardial I/R injury. Our findings uncover a novel role of PKA in oxidative stress and necrosis, which may be exploited to develop new cardioprotective therapies.

GSDMD-Mediated Cardiomyocyte Pyroptosis Promotes Myocardial I/R Injury

Rationale: Pyroptosis is a morphologically and mechanistically distinct form of cell death and is characterized by gasdermin D (GSDMD) or gasdermin E (GSDME)-mediated necrosis with excessive inflammatory factor release. Cardiomyocyte necrosis and inflammation play key roles in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury. However, whether cardiomyocytes undergo pyroptosis and the underlying mechanism in myocardial I/R injury remain unclear. Objective: We aimed to investigate the role of pyroptosis in myocardial I/R injury. Methods and Results: In vivo and in vitro experiments were used to investigate pyroptosis of cardiomyocyte and the associated mechanisms during I/R injury. Wild-type (WT), Myh6-Cre and cardiomyocyte-specific GSDMD-deficient (GSDMD-CKO) male mice were subjected to I/R. Human peripheral blood samples were collected from STEMI (acute ST-segment-elevation myocardial infarction) patients or control patients at 0, 1 and 24 h after PCI (percutaneous coronary intervention) in our department. The serum levels of GSDMD were measured by ELISA. H/R (hypoxia/reoxygenation) induced cardiomyocyte pyroptosis and the release of mature IL-18 but not IL-1β, which mechanistically resulted from GSDMD cleavage by caspase-11 in cardiomyocytes. Furthermore, GSDMD gene deletion blocked H/R-induced cardiomyocyte pyroptosis and IL-18 release. GSDMD and its pyroptosis-inducing N-terminal fragment (GSDMD-N) were upregulated in myocardial tissues after I/R injury. Immunofluorescence analysis showed that GSDMD was mainly localized in cardiomyocytes. GSDMD deficiency in cardiomyocytes significantly reduced the I/R-induced myocardial infarct size. Moreover, increased GSDMD serum levels were detected in patients exhibiting I/R injury 1 h after PCI for STEMI. Conclusions: Our results show that GSDMD-mediated cardiomyocyte pyroptosis is a key event during myocardial I/R injury and that the caspase-11/GSDMD pathway may be essential to this process. Additionally, GSDMD inhibition significantly reduces cardiomyocyte pyroptosis and I/R-induced myocardial injury.