SIRT3 Regulates Clearance of Apoptotic Cardiomyocytes by Deacetylating Frataxin.

BACKGROUND: Efferocytosis is an activity of macrophages that is pivotal for the resolution of inflammation in hypertension. The precise mechanism by which macrophages coordinate efferocytosis and internalize apoptotic cardiomyocytes remains unknown. The aim of this study was to determine whether SIRT3 (sirtuin-3) is required for both apoptotic cardiomyocyte engulfment and anti-inflammatory responses during efferocytosis. METHODS: We generated myeloid SIRT3 knockout mice and FXN (frataxin) knock-in mice carrying an acetylation-defective lysine to arginine K189R mutation (FXNK189R). The mice were given Ang II (angiotensin II) infusion for 7 days. We analyzed cardiac macrophages' mitochondrial iron levels, efferocytosis activity, and phenotype both in vivo and in vitro. RESULTS: We showed that SIRT3 deficiency exacerbated Ang II-induced downregulation of the efferocytosis receptor MerTK (c-Mer tyrosine kinase) and proinflammatory cytokine production, accompanied by disrupted mitochondrial iron homeostasis in cardiac macrophages. Quantitative acetylome analysis revealed that SIRT3 deacetylated FXN at lysine 189. Ang II attenuated SIRT3 activity and enhanced the acetylation level of FXNK189. Acetylated FXN further reduced the synthesis of ISCs (iron-sulfur clusters), resulting in mitochondrial iron accumulation. Phagocytic internalization of apoptotic cardiomyocytes increased myoglobin content, and derived iron ions promoted mitochondrial iron overload and lipid peroxidation. An iron chelator deferoxamine improved the levels of MerTK and efferocytosis, thereby attenuating proinflammatory macrophage activation. FXNK189R mice showed improved macrophage efferocytosis, reduced cardiac inflammation, and suppressed cardiac fibrosis. CONCLUSIONS: The SIRT3-FXN axis has the potential to resolve cardiac inflammation by increasing macrophage efferocytosis and anti-inflammatory activities.

AIFM1, negatively regulated by miR-145-5p, aggravates hypoxia-induced cardiomyocyte injury.

BACKGROUND: Hypoxia-induced apoptosis is linked to the pathogenesis of myocardial infarction. The role of apoptosis-inducing factor mitochondria associated 1 (AIFM1) in cardiomyocyte injury remains unclear. This study was aimed at probing into the role and the underlying regulatory mechanism of AIFM1 in myocardial injury. METHODS: H9c2 cardiomyocytes and C57BL/6 mice were used for myocardial hypoxic/ischemic injury and myocardial infarction animal models. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to evaluate the expression levels of AIFM1 mRNA and miR-145-5p. Western blot was used for examining the expression levels of AIFM1, caspase-3, cleaved caspase-3, p-53, and γ-H2AX. Cell viability was examined by cell counting kit-8 (CCK-8) assay and BrdU assay. Interaction between AIFM1 and miR-145-5p was determined by bioinformatics analysis, qRT-PCR, Western blot, and dual-luciferase reporter assay. RESULTS: AIFM1 expression was markedly highly elevated, while miR-145-5p expression was significantly down-regulated in the myocardial infarction animal model and H9c2 cells under hypoxia. Augmentation of AIFM1 led to a dramatic decrease of cell viability, accompanied by an increase of the secretion of the inflammatory cytokines IL-1ß, TNF-α, IL-6, and the expression of cleaved caspase-3. Furthermore, AIFM1 was identified as a target of miR-145-5p. In addition, miR-145-5p/AIFM1 axis regulated the expression of p53. CONCLUSION: AIFM1 may exacerbate myocardial ischemic injury by promoting inflammation and the injury of cardiomyocytes, and its up-regulation may be partly due to the down-regulation of miR-145-5p.

A randomised trial on the therapeutic effectiveness of bronchoalveolar lavage under fiberoptic bronchoscopy in patients with severe lung infection living in the Tibetan plateau area.

BACKGROUND: People living in plateau areas are prone to upper respiratory tract infections and secondary lung infections. The current study aimed to explore the effects of bronchoalveolar lavage under fiberoptic bronchoscope for the treatment of patients with severe pulmonary infection living in plateau areas. METHODS: 148 patients with severe lung infection admitted to the intensive care unit of Shigatse People's Hospital (Shigatse, Tibet Autonomous Region, China) between July 2019 and January 2021 were enrolled. Patients were randomly assigned to the observational group or the control group. For all patients, basic clinical data including sex, age, body mass index (BMI), blood pressure, diabetes history, stroke history, presence or absence of chronic obstructive pulmonary disease, lung infection (gram-positive bacterial infection, gram-negative bacterial infection, fungal infection, acute lung abscess), surgical history, and postoperative inhalation injury. were collected. The control group received conventional treatment, and the observational group received bronchoalveolar lavage under fiberoptic bronchoscopy. Pearson's correlation was used to analyze the correlations between bronchoalveolar lavage under fiberoptic bronchoscopy and inflammatory factors levels. Logistic regression was used to investigate the correlation between bronchoalveolar lavage under fiberoptic bronchoscopy and the effectiveness of the treatment. RESULTS: Before treatment, no significant difference existed in the basic data of the observational group and the control group. After treatment, the parameters of respiratory mechanics and inflammatory factors in the 2 groups were significantly improved compared with those before treatment (P<0.05). At the same time, in the observational group, the clinical parameters were significantly higher than those of the control group, and the levels of inflammatory factors were significantly lower than those of the control group (all P<0.05). After full adjustment for age, sex, BMI, gram-negative infection, diabetes, and acute lung abscess, compared with the control group, the therapeutic effectiveness in the observational group was increased by 23% (OR =1.23, 95% CI: 1.09-1.51, P=0.007). CONCLUSIONS: For patients with severe lung infection who are resident in high altitude areas, compared with conventional treatments, bronchoalveolar lavage under fiberoptic bronchoscopy can significantly improve chest, lung, and total dynamic compliance, as well as reduce the levels of the inflammatory factors procalcitonin (PCT) and transforming growth factor-ß, thus increasing the effectiveness of the treatment.

Inverse estimation of finite-duration source release mass in river pollution accidents based on adjoint equation method.

Obtaining the pollutant release mass at a timely manner is crucial in emergency response for river pollution accidents. However, compared to the instantaneous source, release mass estimation of finite-duration source has been rarely studied. In addition, few studies involve the influence of partial observation data and observation data with different levels of noise on inversion results. Based on the adjoint equation method (AEM), this study developed a new release mass estimation model to make up the above deficiencies. In this model, one-dimensional physical transport advection-dispersion equation was used as governing equation to describe pollutant transport and the finite-duration sources and instantaneous sources were both considered. Two synthetic experiments and two field experiments were used to evaluate this model. In synthetic experiments, detailed analysis of the influence of observation errors and incomplete concentration data due to equipment failure was conducted. Results indicate that the effect of observation errors on the inverse estimation results was within the relative error of 12%; the incomplete concentration data could also be used to obtain inverse estimation results. The two field experiments gave confidence to the application of this model in release mass estimation in actual pollution accidents with a relative error within 10%. These findings will assist in the decision-making for dealing with actual river pollution accidents.

Inversion of multiple parameters for river pollution accidents using emergency monitoring data.

This study presented a new inversion algorithm on the basis of least squares method for river point pollution sources. A series of numerical experiments was conducted to verify the accuracy of the proposed inversion algorithm. The general solution of the one-dimensional (1D) pollutant transport equation is the governing equation of this method. Pollutant concentrations at various hypothetical monitoring points should be observed at two moments to obtain the point pollution source parameters, namely, velocity, longitudinal dispersion coefficient, emission moment of the pollution source, emission location, and emission intensity. Monitoring error was considered a random noise in the numerical experiments. The inversion result error was 3.69% when the monitoring error was 5%. Although the monitoring error reached 20%, the maximum error of inversion parameters was 8.58%. In addition, the effects of river flow velocity, contaminant decay rates, monitoring point setting, and time intervals between two sampling groups were analyzed in hypothetic cases. PRACTITIONER POINTS: Present a new inversion algorithm for river point pollution sources. Multiple parameters can be obtained by inversion. The unknown river velocity does not affect the result of parameter inversion. Different levels of pollutant concentration monitoring errors are considered.

Correlation between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet.

BACKGROUND: Echo-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis. MATERIAL AND METHODS: ET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta. RESULTS: The rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all P<0.05 vs. controls). In addition, these impairments were greater in the T2 group than in the T1 group (all P<0.05). Finally, MRR% correlated with the distensibility coefficient (r=0.396, P=0.012), arterial compliance (r=0.317, P=0.047), stiffness parameter b (r=-0.406, P=0.009) and one-point pulse wave ß (r=-0.434, P=0.005). CONCLUSIONS: These results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.

Gene microarray analyses for potential biomarkers of single and recurrent venous thromboembolism.

Venous thromboembolism is a major cause of morbidity and mortality with a high recurrence rate. The present study aimed to explore the molecular mechanisms and potential biomarkers of single venous thromboembolism (SVTE) and recurrent venous thromboembolism (RVTE). The microarray dataset GSE19151 was downloaded from Gene Expression Omnibus, which contained data from whole blood samples from 63 healthy controls, 32 SVTE and 38 RVTE patients. Differentially expressed genes (DEGs) in the SVTE and RVTE groups compared with those in the controls were identified using the t­test, followed by clustering analysis of DEGs and samples. Functional and pathway enrichment analyses were performed for DEGs in patients with RVTE and SVTE, as well as specific DEGs in patients with RVTE. The identified 42 DEGs in RVTE were mainly enriched in biological processes of cellular protein metabolism, gene expression and translational elongation as well as in pathways associated with ribosomes, Parkinson's disease and oxidative phosphorylation. In SVTE, 20 DEGs were identified, which were mainly involved in biological processes of biopolymer biosynthesis, translational elongation and cellular protein metabolism as well as pathways associated with ribosomes and cardiac muscle contraction. In RVTE, 22 specific DEGs were mainly involved in translational elongation, negative regulation of the force of heart contraction by chemical signals, cell proliferation, ribosomal pathways and protein export. The identified DEGs of SVTE, including COX7C and UQCRQ, may be potential biomarkers for SVTE, and the specific DEGs of RVTE, including ADRBK1, NDUFA5 and ATP5O, may be potential biomarkers for RVTE.

Xuebijing Ameliorates Sepsis-Induced Lung Injury by Downregulating HMGB1 and RAGE Expressions in Mice.

Xuebijing (XBJ) injection, a traditional Chinese medicine, has been reported as a promising approach in the treatment of sepsis in China. However, its actual molecular mechanisms in sepsis-induced lung injury are yet unknown. Therefore, this study aimed to investigate the beneficial effects of XBJ on inflammation and the underlying mechanisms in a model of caecal ligation and puncture-(CLP-) induced lung injury. The mice were divided into CLP group, CLP+XBJ group (XBJ, 4 mL/kg per 12 hours), and sham group. The molecular and histological examinations were performed on the lung, serum, and bronchoalveolar lavage (BAL) fluid samples of mice at the points of 6, 24, and 48 hours after CLP. The results show that XBJ reduces morphological destruction and neutrophil infiltration in the alveolar space and lung wet/dry weight ratio, which improves mortality of CLP-induced lung injury. Meanwhile, XBJ treatment downregulates high mobility group box protein 1 (HMGB1) and the receptor for advanced glycation end products (RAGE) expression, as well as neutrophil counts, production of IL-1ß, IL-6, and TNF-α in the BAL fluids. In conclusion, these results indicate that XBJ may reduce the mortality through inhibiting proinflammatory cytokines secretion mediated by HMGB1/RAGE axis.

Mechanisms of improved aortic stiffness by arotinolol in spontaneously hypertensive rats.

OBJECTIVES: This study investigates the effects on aortic stiffness and vasodilation by arotinolol and the underlying mechanisms in spontaneously hypertensive rats (SHR). METHODS: The vasodilations of rat aortas, renal and mesenteric arteries were evaluated by isometric force recording. Nitric oxide (NO) was measured in human aortic endothelial cells (HAECs) by fluorescent probes. Sixteen-week old SHRs were treated with metoprolol (200 mg·kg-1·d⁻¹), arotinolol (30 mg·kg-1·d⁻¹) for 8 weeks. Central arterial pressure (CAP) and pulse wave velocity (PWV) were evaluated via catheter pressure transducers. Collagen was assessed by immunohistochemistry and biochemistry assay, while endothelial nitric oxide synthase (eNOS) and eNOS phosphorylation (p-eNOS) of HAECs or aortas were analyzed by western blotting. RESULTS: Arotinolol relaxed vascular rings and the relaxations were attenuated by Nω-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and the absence of endothelium. Furthermore, arotinolol-induced relaxations were attenuated by 4-aminopyridine (4-AP, Kv channels blocker). Arotinolol produced more nitric oxide compared to metoprolol and increased the expression of p-eNOS in HAECs. These results indicated that arotinolol-induced vasodilation involves endothelium-derived NO and Kv channels. The treatement with arotinolol in 8 weeks, but not metoprolol, markedly decreased CAP and PWV. Biochemistry assay and immunohistochemistry showed that aortic collagen depositions in the arotinolol groups were reduced compared with SHRs with metoprolol. Moreover, eNOS phosphorylation was significantly increased in aortinolol-treated SHR compared with SHRs with metoprolol. CONCLUSIONS: Arotinolol improves arterial stiffness in SHR, which involved in increasing NO and decreasing collagen contents in large arteries.

N-acetylcysteine-pretreated human embryonic mesenchymal stem cell administration protects against bleomycin-induced lung injury.

INTRODUCTION: The transplantation of mesenchymal stem cells (MSCs) has been reported to be a promising approach in the treatment of acute lung injury. However, the poor efficacy of transplanted MSCs is one of the serious handicaps in the progress of MSC-based therapy. Therefore, the purpose of this study was to investigate whether the pretreatment of human embryonic MSCs (hMSCs) with an antioxidant, namely N-acetylcysteine (NAC), can improve the efficacy of hMSC transplantation in lung injury. METHODS: In vitro, the antioxidant capacity of NAC-pretreated hMSCs was assessed using intracellular reactive oxygen species (ROS) and glutathione assays and cell adhesion and spreading assays. In vivo, the therapeutic potential of NAC-pretreated hMSCs was assessed in a bleomycin-induced model of lung injury in nude mice. RESULTS: The pretreatment of hMSCs with NAC improved antioxidant capacity to defend against redox imbalances through the elimination of cellular ROS, increasing cellular glutathione levels, and the enhancement of cell adhesion and spreading when exposed to oxidative stresses in vitro. In addition, the administration of NAC-pretreated hMSCs to nude mice with bleomycin-induced lung injury decreased the pathological grade of lung inflammation and fibrosis, hydroxyproline content and numbers of neutrophils and inflammatory cytokines in bronchoalveolar lavage fluid and apoptotic cells, while enhancing the retention and proliferation of hMSCs in injured lung tissue and improving the survival rate of mice compared with results from untreated hMSCs. CONCLUSIONS: The pretreatment of hMSCs with NAC could be a promising therapeutic approach to improving cell transplantation and, therefore, the treatment of lung injury.