RNF149 Destabilizes IFNGR1 in Macrophages to Favor Post-Infarction Cardiac Repair.

BACKGROUND: Macrophage-driven inflammation critically involves in cardiac injury and repair following myocardial infarction (MI). However, the intrinsic mechanisms that halt the immune response of macrophages, which is critical to preserve homeostasis and effective infarct repair, remain to be fully defined. Here, we aimed to determine the ubiquitination-mediated regulatory effects on averting exaggerated inflammatory responses in cardiac macrophages. METHODS: We used transcriptome analysis of mouse cardiac macrophages and bone marrow-derived macrophages to identify the E3 ubiquitin ligase RNF149 (RING finger protein 149) as a modulator of macrophage response to MI. Employing loss-of-function methodologies, bone marrow transplantation approaches, and adenovirus-mediated RNF149 overexpression in macrophages, we elucidated the functional role of RNF149 in MI. We explored the underlying mechanisms through flow cytometry, transcriptome analysis, immunoprecipitation/mass spectrometry analysis, and functional experiments. RNF149 expression was measured in the cardiac tissues of patients with acute MI and healthy controls. RESULTS: RNF149 was highly expressed in murine and human cardiac macrophages at the early phase of MI. Knockout of RNF149, transplantation of Rnf149-/- bone marrow, and bone marrow macrophage-specific RNF149-knockdown markedly exacerbated cardiac dysfunction in murine MI models. Conversely, overexpression of RNF149 in macrophages attenuated the ischemia-induced decline in cardiac contractile function. RNF149 deletion increased infiltration of proinflammatory monocytes/macrophages, accompanied by a hastened decline in reparative subsets, leading to aggravation of myocardial apoptosis and impairment of infarct healing. Our data revealed that RNF149 in infiltrated macrophages restricted inflammation by promoting ubiquitylation-dependent proteasomal degradation of IFNGR1 (interferon gamma receptor 1). Loss of IFNGR1 rescued deleterious effects of RNF149 deficiency on MI. We further demonstrated that STAT1 activation induced Rnf149 transcription, which, in turn, destabilized the IFNGR1 protein to counteract type-II IFN (interferon) signaling, creating a feedback control mechanism to fine-tune macrophage-driven inflammation. CONCLUSIONS: These findings highlight the significance of RNF149 as a molecular brake on macrophage response to MI and uncover a macrophage-intrinsic posttranslational mechanism essential for maintaining immune homeostasis and facilitating cardiac repair following MI.

Orphan Nuclear Receptor NR4A3 Promotes Vascular Calcification via Histone Lactylation.

BACKGROUND: Medial arterial calcification is a chronic systemic vascular disorder distinct from atherosclerosis and is commonly observed in patients with chronic kidney disease, diabetes, and aging individuals. We previously showed that NR4A3 (nuclear receptor subfamily 4 group A member 3), an orphan nuclear receptor, is a key regulator in apo (apolipoprotein) A-IV-induced atherosclerosis progression; however, its role in vascular calcification is poorly understood. METHODS: We generated NR4A3-/- mice and 2 different types of medial arterial calcification models to investigate the biological roles of NR4A3 in vascular calcification. RNA-seq was performed to determine the transcriptional profile of NR4A3-/- vascular smooth muscle cells under ß-glycerophosphate treatment. We integrated Cleavage Under Targets and Tagmentation analysis and RNA-seq data to further investigate the gene regulatory mechanisms of NR4A3 in arterial calcification and target genes regulated by histone lactylation. RESULTS: NR4A3 expression was upregulated in calcified aortic tissues from chronic kidney disease mice, 1,25(OH)2VitD3 overload-induced mice, and human calcified aorta. NR4A3 deficiency preserved the vascular smooth muscle cell contractile phenotype, inhibited osteoblast differentiation-related gene expression, and reduced calcium deposition in the vasculature. Further, NR4A3 deficiency lowered the glycolytic rate and lactate production during the calcification process and decreased histone lactylation. Mechanistic studies further showed that NR4A3 enhanced glycolysis activity by directly binding to the promoter regions of the 2 glycolysis genes ALDOA and PFKL and driving their transcriptional initiation. Furthermore, histone lactylation promoted medial calcification both in vivo and in vitro. NR4A3 deficiency inhibited the transcription activation and expression of Phospho1 (phosphatase orphan 1). Consistently, pharmacological inhibition of Phospho1 attenuated calcium deposition in NR4A3-overexpressed vascular smooth muscle cells, whereas overexpression of Phospho1 reversed the anticalcific effect of NR4A3 deficiency in vascular smooth muscle cells. CONCLUSIONS: Taken together, our findings reveal that NR4A3-mediated histone lactylation is a novel metabolome-epigenome signaling cascade mechanism that participates in the pathogenesis of medial arterial calcification.

DYRK1B-STAT3 Drives Cardiac Hypertrophy and Heart Failure by Impairing Mitochondrial Bioenergetics.

BACKGROUND: Heart failure is a global public health issue that is associated with increasing morbidity and mortality. Previous studies have suggested that mitochondrial dysfunction plays critical roles in the progression of heart failure; however, the underlying mechanisms remain unclear. Because kinases have been reported to modulate mitochondrial function, we investigated the effects of DYRK1B (dual-specificity tyrosine-regulated kinase 1B) on mitochondrial bioenergetics, cardiac hypertrophy, and heart failure. METHODS: We engineered DYRK1B transgenic and knockout mice and used transverse aortic constriction to produce an in vivo model of cardiac hypertrophy. The effects of DYRK1B and its downstream mediators were subsequently elucidated using RNA-sequencing analysis and mitochondrial functional analysis. RESULTS: We found that DYRK1B expression was clearly upregulated in failing human myocardium and in hypertrophic murine hearts, as well. Cardiac-specific DYRK1B overexpression resulted in cardiac dysfunction accompanied by a decline in the left ventricular ejection fraction, fraction shortening, and increased cardiac fibrosis. In striking contrast to DYRK1B overexpression, the deletion of DYRK1B mitigated transverse aortic constriction-induced cardiac hypertrophy and heart failure. Mechanistically, DYRK1B was positively associated with impaired mitochondrial bioenergetics by directly binding with STAT3 to increase its phosphorylation and nuclear accumulation, ultimately contributing toward the downregulation of PGC-1α (peroxisome proliferator-activated receptor gamma coactivator-1α). Furthermore, the inhibition of DYRK1B or STAT3 activity using specific inhibitors was able to restore cardiac performance by rejuvenating mitochondrial bioenergetics. CONCLUSIONS: Taken together, the findings of this study provide new insights into the previously unrecognized role of DYRK1B in mitochondrial bioenergetics and the progression of cardiac hypertrophy and heart failure. Consequently, these findings may provide new therapeutic options for patients with heart failure.

[68Ga]Ga-DOTA-FAPI-04 PET/MR in patients with acute myocardial infarction: potential role of predicting left ventricular remodeling.

PURPOSE: To assess predictive value of 68Ga-labeled fibroblast activation protein inhibitor-04 ([68Ga]Ga-DOTA-FAPI-04) PET/MR for late left ventricular (LV) remodeling in patients with ST-segment elevated myocardial infarction (STEMI). METHODS: Twenty-six patients with STEMI were included in the study. [68Ga]Ga-DOTA-FAPI-04 PET/MR was performed at baseline and at average 12 months after STEMI. LV remodeling was defined as >10% increase in LV end-systolic volume (LVESV) from baseline to 12 months. RESULTS: The LV remodeling group demonstrated higher [68Ga]Ga-DOTA-FAPI-04 uptake volume (UV) at baseline than the non-LV remodeling group (p < 0.001). [68Ga]Ga-DOTA-FAPI-04 UV at baseline was a significant predictor (OR = 1.048, p = 0.011) for LV remodeling at 12 months after STEMI. Compared to clinical information, MR imaging and cardiac function parameters at baseline, [68Ga]Ga-DOTA-FAPI-04 UV demonstrated better predictive ability (AUC = 0.938, p < 0.001) for late LV remodeling, with sensitivity of 100.0% and specificity of 81.3%. CONCLUSIONS: [68Ga]Ga-DOTA-FAPI-04 PET/MR is an effective tool to non-invasively quantify myocardial fibroblasts activation, and baseline [68Ga]Ga-DOTA-FAPI-04 UV may have potential predictive value for late LV remodeling.

Lgr4 Governs a Pro-Inflammatory Program in Macrophages to Antagonize Post-Infarction Cardiac Repair.

RATIONALE: Macrophages are critically involved in wound healing following myocardial infarction (MI). Lgr4, a member of LGR (leucine-rich repeat-containing G protein-coupled receptor) family, is emerging as a regulator of macrophage-associated immune responses. However, the contribution of Lgr4 to macrophage phenotype and function in the context of MI remains unclear. OBJECTIVE: To determine the role of macrophage Lgr4 in MI and to dissect the underlying mechanisms. METHODS AND RESULTS: During early inflammatory phase of MI, infarct macrophages rather than neutrophils expressed high level of Lgr4. Macrophage-specific Lgr4 knockout mice had no baseline cardiovascular defects but manifested improved heart function, modestly reduced infarct size, decreased early mortality due to cardiac rupture, and ameliorated adverse remodeling after MI. Improved outcomes in macrophage-specific Lgr4 knockout mice subjected to MI were associated with mitigated ischemic injury and optimal infarct healing, as determined by reduction of cardiac apoptosis in the peri-infarct zone, attenuation of local myocardial inflammatory response, decrease of matrix metalloproteinase expression in the infarct, enhancement of angiogenesis, myofibroblast proliferation, and collagen I deposition in reparative granulation tissue as well as formation of collagen-rich scar. More importantly, macrophage-specific Lgr4 knockout infarcts had reduced numbers of infiltrating leukocytes and inflammatory macrophages but harbored abundant reparative macrophage subsets. Lgr4-null infarct macrophages exhibited a less inflammatory transcriptional signature. These findings were further supported by transcriptomic profiling data showing repression of multiple pathways and broad-spectrum genes associated with proinflammatory responses in macrophage-specific Lgr4 knockout infarcts. Notably, we discovered that Lgr4-mediated functional phenotype programing in infarct macrophages was at least partly attributed to regulation of AP (activator protein)-1 activity. We further demonstrated that the synergistic effects of Lgr4 on AP-1 activation in inflammatory macrophages occurred via enhancing CREB (cAMP response element-binding protein)-mediated c-Fos, Fosl1, and Fosb transactivation. CONCLUSIONS: Together, our data highlight the significance of Lgr4 in governing proinflammatory phenotype of infarct macrophages and postinfarction repair.

Roxadustat Does Not Affect Platelet Production, Activation, and Thrombosis Formation.

Objective: Roxadustat is a new medication for the treatment of renal anemia. EPO (erythropoietin)-the current treatment standard-has been reported to enhance platelet activation and production. However, to date, the effect of roxadustat on platelets is unclear. To address this deficiency, herein, we have evaluated the effect of roxadustat on platelet production and function. Approach and Results: We performed several mouse platelet functional assays in the presence/absence of in vitro and in vivo roxadustat treatment. Both healthy and 5/6 nephrectomized mice were utilized. The effect of roxadustat on platelet function of healthy volunteers and chronic kidney disease patients was also evaluated. For platelet production, megakaryocyte maturation and proplatelet formation were assayed in vitro. Peripheral platelet and bone marrow megakaryocyte counts were also determined. We found that roxadustat could not stimulate washed platelets directly, and platelet aggregation, spreading, clot retraction, and P-selectin/JON/A exposure were similar with or without in vitro or in vivo roxadustat treatment among both healthy and 5/6 nephrectomized mice. In vivo mouse thrombosis models were additionally performed, and no differences were detected between the vehicle and roxadustat treatment groups. EPO, which was considered a positive control in the present study, promoted platelet function and production as reported previously. Megakaryocyte maturation and proplatelet formation were also not significantly different between control mice and those treated with roxadustat. After receiving roxadustat for 14 days, no difference in the peripheral platelet count was observed in the mice. Conclusions: Administration of roxadustat has no significant impact on platelet production and function.

The validity, reliability and feasibility of four instruments for assessing the consciousness of stroke patients in a neurological intensive care unit compared.

BACKGROUND: Early rehabilitation is the foundation for recovery for those admitted to an intensive care unit. Appropriate assessment of consciousness is needed before any rehabilitative intervention begins. METHODS: This prospective study compared the validity, reliability and applicability of the sedation-agitation scale, the Richmond Agitation-Sedation Scale, the motor activity assessment scale and the Glasgow Coma Scale in a working neurological intensive care unit. Eighty-three stroke patients were assessed with the four scales by the same 3 raters acting independently: a senior physician, a senior therapist and a trainee. That generated 996 assessment records for comparison. RESULTS: Good agreement (r=0.98-0.99) was found among the sedation-agitation scale, the Richmond Agitation-Sedation Scale, the motor activity assessment scale scores, but the Glasgow Coma Scale ratings correlated less well (r=0.72-0.76) with the others. Consistent results were also found among the three raters. After stratification of the ratings by age, gender, level of consciousness and Acute Physiology and Chronic Health Evaluation score, the scales reported significant differences among the levels of consciousness and among those with different Acute Physiology and Chronic Health Evaluation results, but not with different age or gender strata. CONCLUSIONS: The four instruments tested are all reliable enough and feasible for use as a tool for consciousness screening in a neurological intensive care unit.

Dectin-1 Contributes to Myocardial Ischemia/Reperfusion Injury by Regulating Macrophage Polarization and Neutrophil Infiltration.

BACKGROUND: Macrophage-associated immune response plays an important role in myocardial ischemia/reperfusion (IR) injury. Dectin-1, expressed mainly on activated myeloid cells, is crucial for the regulation of immune homeostasis as a pattern recognition receptor. However, its effects and roles during the myocardial IR injury remain unknown. METHODS: Genetic ablation, antibody blockade, or Dectin-1 activation, along with the adoptive bone marrow transfer chimeric model, was used to determine the functional significance of Dectin-1 in myocardial IR injury. Immune cell filtration and inflammation were examined by flow cytometry, quantitative real-time polymerase chain reaction, and immunohistochemistry. Moreover, Dectin-1+ cells were analyzed by flow cytometry in the blood of patients with ST-segment-elevation myocardial infarction and stable patients with normal coronary artery (control). RESULTS: We demonstrated that Dectin-1 expression observed on the bone marrow-derived macrophages is increased in the heart during the early phase after IR injury. Dectin-1 deficiency and antibody-mediated Dectin-1 inhibition led to a considerable improvement in cardiac function, accompanied by a reduction in cardiomyocyte apoptosis, which was associated with a decrease in M1 macrophage polarization and Ly-6C+ monocyte and neutrophil infiltration. Activation of Dectin-1 with its agonist had the opposite effects. Furthermore, Dectin-1 contributed to neutrophil recruitment through the regulation of Cxcl1 and granulocyte colony-stimulating factor expression. In addition, Dectin-1-dependent interleukin-23/interleukin-1ß production was shown to be essential for interleukin-17A expression by γδT cells, leading to neutrophil recruitment and myocardial IR injury. Furthermore, we demonstrated that circulating Dectin-1+CD14++CD16- and Dectin-1+CD14++CD16+ monocyte levels were significantly higher in patients with ST-segment-elevation myocardial infarction than in controls and positively correlated with the severity of cardiac dysfunction. CONCLUSIONS: Our results reveal a crucial role of Dectin-1 in the process of mouse myocardial IR injury and provide a new, clinically significant therapeutic target.

Impact of Cardiovascular Disease on Clinical Characteristics and Outcomes of Coronavirus Disease 2019 (COVID-19).

BACKGROUND: To investigate the effect of cardiovascular disease (CVD) on the global pandemic, coronavirus disease 2019 (COVID-19), we analyzed the cases of laboratory-confirmed COVID-19 patients in Wuhan.Methods and Results:Data were extracted from the medical records. SARS-CoV-2 RNA was confirmed by RT-PCR. A total of 33 (53.2%) of 62 cases with CVD, who had higher prevalence of severe COVID-19 compared with non-CVD patients (P=0.027). The median age of all patients was 66.0 (53.3, 73.0) years old. Coronary artery disease (11.3%) and hypertension (38.7%) were the common coexisting CVDs in COVID-19 patients. High-sensitivity cardiac troponin I (hs-cTnI), creatinine, high-density lipoprotein-cholesterol, interleukin-6, C-reactive protein, prothrombin time, and D-dimer levels in the severe COVID-19 with CVD group were higher than in the non-severe COVID-19 with CVD group (P<0.05). For all patients, chest computed tomography (CT) showed ground-glass opacity (66.1%), local (21.0%), bilateral (77.4%), and interstitial abnormalities (4.8%). In COVID-19 patients with CVD, 27 (81.8%) were cured and discharged. 6 (18.2%) remained in hospital, including 2 (3.2%) patients requiring intubation and mechanical ventilation. The hs-cTnI levels in the remaining hospitalized patients were higher than in the discharged patients (P=0.047). CONCLUSIONS: CVDs play a vital role in the disease severity of COVID-19. COVID-19 could result in myocardial injury, which affects the prognosis of COVID-19.

Fatty acid-binding protein 3 contributes to ischemic heart injury by regulating cardiac myocyte apoptosis and MAPK pathways.

Fatty acid-binding protein 3 (FABP3), a low-molecular-weight protein, participates in lipid transportation, storage, signaling transduction, oxidation, and transcription regulation. Here, we investigated the expression and function of FABP3 in ischemic heart diseases and explored the mechanisms by which FABP3 affected remodeling after myocardial infarction (MI). We showed that ischemic or hypoxic conditions upregulated FABP3 expression in vivo and in vitro. Notably, overexpression of FABP3 induced more myocyte apoptosis in the infarction and border areas and aggravated cardiac dysfunction, with lower left ventricular ejection fraction. Meanwhile, overexpression of FABP3 drastically promoted death and apoptosis of neonatal rat ventricular cardiomyocytes under hypoxia. Furthermore, deficiency of FABP3 exerted protective effects against ischemic heart injuries by decreasing cardiac myocyte apoptosis and heart remodeling after MI. We found that overexpression of FABP3 upregulated the phosphorylation of MAPK signaling pathway and decreased phosphorylated Akt levels, which may account for the augmentation of apoptosis and remodeling after MI. To the best of our knowledge, this is the first study to demonstrate that deficiency of FABP3 would protect cardiac myocytes from apoptosis and alleviate cardiac remodeling after MI, suggesting FABP3 as a potential target to preserve cardiac function after MI. NEW & NOTEWORTHY It is an undisputable fact that myocyte apoptosis plays a crucial role in cardiac remodeling and the development of heart failure after myocardial infarction. Here, fatty acid-binding protein 3 deficiency improved myocardial structural remodeling and function by decreasing cell apoptosis and regulating MAPK signaling pathways. We suppose that fatty acid-binding protein 3 may be regarded as a potential intervention approach to preserve cardiomyocytes during myocardial infarction.

Dectin-2 Deficiency Modulates Th1 Differentiation and Improves Wound Healing After Myocardial Infarction.

RATIONALE: Macrophages are involved in wound healing after myocardial infarction (MI). The role of Dectin-2, a pattern recognition receptor mainly expressed on myeloid cells, in the infarct healing remains unknown. OBJECTIVE: The aim of this study is to determine whether Dectin-2 signaling is involved in the healing process and cardiac remodeling after MI and to elucidate the underlying molecular mechanisms. METHODS AND RESULTS: In a mouse model of permanent coronary ligation, Dectin-2, mainly expressed in macrophages, was shown to be increased in the early phase after MI. Dectin-2 knockout mice showed an improvement in the infarct healing and cardiac remodeling, compared with wild-type mice, which was demonstrated by significantly lower mortality because of cardiac rupture, increased wall thickness, and better cardiac function. Increased expression of α-smooth muscle actin and collagen I/III was observed, whereas the levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 were decreased in the hearts of Dectin-2 knockout mice after MI. Dectin-2 deficiency inhibited the rate of apoptotic and necrotic cell death. However, Dectin-2 did not affect immune cell infiltration and macrophage polarization, but it led to a stronger activation of the Th1/interferon-γ immune reaction, through the enhancement of interleukin-12 production in the heart. Interferon-γ was shown to downregulate transforming growth factor-ß-induced expression of α-smooth muscle actin and collagen I/III in isolated cardiac fibroblasts, leading to a decrease in migration and myofibroblast differentiation. Finally, Dectin-2 knockout improved myocardial ischemia-reperfusion injury and infarct healing. CONCLUSIONS: Dectin-2 leads to an increase in cardiac rupture, impairs wound healing, and aggravates cardiac remodeling after MI through the modulation of Th1 differentiation.

Interleukin-34 Levels Were Associated with Prognosis in Patients with Acute Myocardial Infarction.

Inflammatory factors have specific value in acute myocardial infarction (AMI). Our previous studies have identified the prognostic value of interleukin (IL)-34 during chronic heart failure. However, the potential impact of IL-34 on AMI remains unknown.Serum IL-34 was measured in 287 AMI patients, and they were followed up for the composite endpoint, including cardiovascular death, heart failure hospitalization, recurrent nonfatal myocardial infarction (MI), and nonfatal stroke.IL-34 levels were significantly associated with the presence of heart failure at baseline and its aggravation after a year. During the five-year follow-up, there was a significant increase in the risk of the composite endpoint (hazard ratio [HR] 1.38 [95% confidence intervals (CI) 1.12-1.70], P < 0.01) and cardiovascular death (HR 1.48 [95%CI 1.03-2.27], P = 0.03) after full adjustment as IL-34 levels increased.Higher IL-34 levels in the acute phase were associated with an increased risk of heart failure after MI and poor prognosis.

Tubular epithelial C1orf54 mediates protection and recovery from acute kidney injury.

Acute kidney injury (AKI) incidence among hospitalized patients is increasing steadily. Despite progress in prevention strategies and support measures, AKI remains correlated with high mortality, particularly among ICU patients, and no effective AKI therapy exists. Here, we investigated the function in kidney ischaemia-reperfusion injury (IRI) of C1orf54, a newly identified protein encoded by an open reading frame on chromosome 1. C1orf54 expression was high in kidney and low in heart, liver, spleen, lung and skeletal muscle in healthy mice, and in the kidney, C1orf54 was expressed in tubular epithelial cells (TECs), but not in glomeruli. C1orf54 expression was markedly decreased on Day 1 after kidney IRI and then gradually recovered to baseline levels by Day 7. Notably, relative to wild-type mice, C1orf54-knockout mice exhibited impaired TEC proliferation and delayed recovery after kidney IRI, which led to deteriorated renal function and increased mortality. Conversely, adenovirus-mediated C1orf54 overexpression promoted TEC proliferation and ameliorated kidney pathology, which resulted in accelerated renal repair and improved renal function. Mechanistically, C1orf54 was found to promote TEC proliferation through PI3K/AKT signalling. Thus, C1orf54 holds considerable potential as a therapeutic target in kidney IRI.

Renal recruitment of B lymphocytes exacerbates tubulointerstitial fibrosis by promoting monocyte mobilization and infiltration after unilateral ureteral obstruction.

Renal fibrosis is a significant threat to public health globally. Diverse primary aetiologies eventually result in chronic kidney disease (CKD) and immune cells influence this process. The roles of monocytes/macrophages, T cells, and mast cells have been carefully examined, whilst only a few studies have focused on the effect of B cells. We investigated B-cell function in tubulointerstitial fibrosis induced by unilateral ureteral obstruction (UUO), using genetic B-cell-deficient µMT mice or CD20 antibody-mediated B-cell-depleted mice. Obstructed kidneys of µMT and anti-CD20-treated mice showed lower levels of monocyte/macrophage infiltration and collagen deposition compared to wild-type mice. Mechanistically, anti-CD20 attenuated UUO-induced alterations of renal tumour necrosis factor-α (TNF-α), vascular cell adhesion molecule 1 (VCAM-1) pro-inflammatory genes, and CC chemokine ligand-2 (CCL2) essential for monocyte recruitment; B cells were one of the main sources of CCL2 in post-UUO kidneys. Neutralization of CCL2 reduced monocyte/macrophage influx and fibrotic changes in obstructed kidneys. Therefore, early-stage accumulation of B cells in the kidney accelerated monocyte/macrophage mobilization and infiltration, aggravating the fibrosis resulting from acutely induced kidney nephropathy. © 2016 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Naoxintong attenuates Ischaemia/reperfusion Injury through inhibiting NLRP3 inflammasome activation.

Naoxintong (NXT) is a Chinese Materia Medica standardized product extracted from 16 various kinds of Chinese traditional herbal medicines including Salvia miltiorrhiza, Angelica sinensis, Astragali Radix. Naoxintong is clinically effective in treating ischaemia heart disease. Nucleotide-binding oligomerization domain-Like Receptor with a Pyrin domain 3 (NLRP3) inflammasome has been critically involved in myocardial ischaemia/reperfusion (I/R) injury. Here, we have been suggested that NXT might attenuate myocardial I/R injury via suppression of NLRP3 inflammasome activation. Male C57BL6 mice were subjected to myocardial I/R injury via 45 min. coronary ligation and release for the indicated times. Naoxintong (0.7 g/kg/day) and PBS were orally administrated for 2 weeks before surgery. Cardiac function assessed by echocardiography was significantly improved in the NXT group compared to PBS group at day 2 after myocardial I/R. NLRP3 inflammasome activation is crucially involved in the initial inflammatory response after myocardial I/R injury, leading to cleaved caspase-1, mature interleukin (IL)-1ß production, accompanying by macrophage and neutrophil infiltration. The cardioprotective effect of NXT was associated with a diminished NLRP3 inflammasome activation, decreased pro-inflammatory macrophage (M1 macrophages) and neutrophil infiltration after myocardial I/R injury. In addition, serum levels of IL-1ß, indicators of NLRP3 inflammasome activation, were also significantly suppressed in the NXT treated group after I/R injury. Naoxintong exerts cardioprotive effects at least partly by suppression of NLRP3 inflammasome activation in this I/R injury model.

Adventitial CXCL1/G-CSF expression in response to acute aortic dissection triggers local neutrophil recruitment and activation leading to aortic rupture.

RATIONALE: In-hospital outcomes are generally acceptable in patients with type B dissection; however, some patients present with undesirable complications, such as aortic expansion and rupture. Excessive inflammation is an independent predictor of adverse clinical outcomes. OBJECTIVE: We have investigated the underlying mechanisms of catastrophic complications after acute aortic dissection (AAD) in mice. METHODS AND RESULTS: When angiotensin II was administered in lysyl oxidase inhibitor-preconditioned mice, AAD emerged within 24 hours. The dissection was initiated at the proximal site of the descending thoracic aorta and propagated distally into an abdominal site. Dissection of the aorta caused dilatation, and ≈70% of the mice died of aortic rupture. AAD triggered CXCL1 and granulocyte-colony stimulating factor expression in the tunica adventitia of the dissected aorta, leading to elevation of circulating CXCL1/granulocyte-colony stimulating factor levels. Bone marrow CXCL12 was reduced. These chemokine changes facilitated neutrophil egress from bone marrow and infiltration into the aortic adventitia. Interference of CXCL1 function using an anti-CXCR2 antibody reduced neutrophil accumulation and limited aortic rupture post AAD. The tunica adventitia of the expanded dissected aorta demonstrated high levels of interleukin-6 (IL-6) expression. Neutrophils were the major sources of IL-6, and CXCR2 neutralization significantly reduced local and systemic levels of IL-6. Furthermore, disruption of IL-6 effectively suppressed dilatation and rupture of the dissected aorta without any influence on the incidence of AAD and neutrophil mobilization. CONCLUSIONS: Adventitial CXCL1/granulocyte-colony stimulating factor expression in response to AAD triggers local neutrophil recruitment and activation. This leads to adventitial inflammation via IL-6 and results in aortic expansion and rupture.

Cardiac Sirt1 mediates the cardioprotective effect of caloric restriction by suppressing local complement system activation after ischemia-reperfusion.

Caloric restriction (CR) confers cardioprotection against ischemia-reperfusion (I/R) injury. We previously found the essential roles of endothelial nitric oxide synthase in the development of CR-induced cardioprotection and Sirt1 activation during CR (Shinmura K, Tamaki K, Ito K, Yan X, Yamamoto T, Katsumata Y, Matsuhashi T, Sano M, Fukuda K, Suematsu M, Ishii I. Indispensable role of endothelial nitric oxide synthase in caloric restriction-induced cardioprotection against ischemia-reperfusion injury.Am J Physiol Heart Circ Physiol 308: H894-H903, 2015). However, the exact mechanism by which Sirt1 in cardiomyocytes mediates the cardioprotective effect of CR remains undetermined. We subjected cardiomyocyte-specific Sirt1 knockout (CM-Sirt1(-/-)) mice and the corresponding control mice to either 3-mo ad libitum feeding or CR (-40%). Isolated perfused hearts were subjected to 25-min global ischemia, followed by 60-min reperfusion. The recovery of left ventricle function after I/R was improved, and total lactate dehydrogenase release into the perfusate during reperfusion was attenuated in the control mice treated with CR, but a similar cardioprotective effect of CR was not observed in the CM-Sirt1(-/-)mice. The expression levels of cardiac complement component 3 (C3) at baseline and the accumulation of C3 and its fragments in the ischemia-reperfused myocardium were attenuated by CR in the control mice, but not in the CM-Sirt1(-/-)mice. Resveratrol treatment also attenuated the expression levels of C3 protein in cultured neonatal rat ventricular cardiomyocytes. Moreover, the degree of myocardial I/R injury in conventional C3 knockout (C3(-/-)) mice treated with CR was similar to that in the ad libitum-fed C3(-/-)mice, although the expression levels of Sirt1 were enhanced by CR. These results demonstrate that cardiac Sirt1 plays an essential role in CR-induced cardioprotection against I/R injury by suppressing cardiac C3 expression. This is the first report suggesting that cardiac Sirt1 regulates the local complement system during CR.

Lung natural killer cells play a major counter-regulatory role in pulmonary vascular hyperpermeability after myocardial infarction.

RATIONALE: Natural killer (NK) cells are lymphocytes of the innate immune system that play specialized and niche-specific roles in distinct organs. OBJECTIVE: We investigated the possible function of NK cells in the pathogenesis of congestive heart failure after myocardial infarction. METHODS AND RESULTS: Depletion of NK cells from mice had little effect on cytokine expression (tumor necrosis factor-α, interleukin [IL]-6, and IL-1ß), neutrophil and macrophage infiltration into infarcted myocardium, or left ventricular remodeling after myocardial infarction. However, these mice exhibited severe respiratory distress associated with protein-rich, high-permeability alveolar edema accompanied by neutrophil infiltration. In addition, there were 20-fold more NK cells in the mouse lungs than in heart, and these cells were accumulated around the vasculature. CD107a-positive and interferon-γ-positive cell populations were unchanged, whereas IL-10-positive populations increased. Adoptive transfer of NK cells from wild-type mice, but not from IL-10 knockout mice, into the NK cell-depleted mice rescued the respiratory phenotype. IL-1ß-mediated dextran leakage from a lung endothelial cell monolayer was also blocked by coculture with NK cells from wild-type mice but not from IL-10 knockout mice. CONCLUSIONS: This study is the first to identify a critical role for lung NK cells in protecting lung from the development of cardiogenic pulmonary edema after myocardial infarction.

Activation of pyruvate dehydrogenase by dichloroacetate has the potential to induce epigenetic remodeling in the heart.

Dichloroacetate (DCA) promotes pyruvate entry into the Krebs cycle by inhibiting pyruvate dehydrogenase (PDH) kinase and thereby maintaining PDH in the active dephosphorylated state. DCA has recently gained attention as a potential metabolic-targeting therapy for heart failure but the molecular basis of the therapeutic effect of DCA in the heart remains a mystery. Once-daily oral administration of DCA alleviates pressure overload-induced left ventricular remodeling. We examined changes in the metabolic fate of pyruvate carbon (derived from glucose) entering the Krebs cycle by metabolic interventions of DCA. (13)C6-glucose pathway tracing analysis revealed that instead of being completely oxidized in the mitochondria for ATP production, DCA-mediated PDH dephosphorylation results in an increased acetyl-CoA pool both in control and pressure-overloaded hearts. DCA induces hyperacetylation of histone H3K9 and H4 in a dose-dependent manner in parallel to the dephosphorylation of PDH in cultured cardiomyocytes. DCA administration increases histone H3K9 acetylation in in vivo mouse heart. Interestingly, DCA-dependent histone acetylation was associated with an up-regulation of 2.3% of genes (545 out of 23,474 examined). Gene ontology analysis revealed that these genes are highly enriched in transcription-related categories. This evidence suggests that sustained activation of PDH by DCA results in an overproduction of acetyl-CoA, which exceeds oxidation in the Krebs cycle and results in histone acetylation. We propose that DCA-mediated PDH activation has the potential to induce epigenetic remodeling in the heart, which, at least in part, forms the molecular basis for the therapeutic effect of DCA in the heart.