Glucose regulates the intrinsic inflammatory response of the heart to surgically induced hypothermic ischemic arrest and reperfusion

The role and regulatory mechanism of HIF-1α in myocardial injury in rats undergoing cardiopulmonary bypass

BACKGROUND

Hypoxia-inducible factor-1alpha (HIF-1α) is a transcription factor implicated in physiological and pathological responses to hypoxia. The present study aims to investigate the effect and mechanism of HIF-1α on cardiopulmonary bypass (CPB)-related myocardial injury, thereby conferring a theoretical basis for the clinical treatment of myocardial injury in CPB.

METHODS

An experimental model of CPB was established in rats by surgery. Adenovirus-packaged overexpression vectors and antiagomiRNA were used to overexpress HIF-1α and NR4A1 or inhibit miR-124-3p expression in rat myocardial tissues, respectively. qRT-PCR and Western blot detected HIF-1α, miR-124-3p, and NR4A1 expression in myocardial tissues. The rat cardiac function was monitored through an echocardiogram. The rat plasma at different stages of CPB was collected, followed by the detection of IL-6, cTnT, CK-MB, and IL-1β. TUNEL staining measured apoptosis in myocardial tissues. ChIP assay analysed the enrichment of HIF-1α on the miR-124-3p promoter. The binding relationships between HIF-1α and miR-124-3p promoter sequence and between miR-124-3p and NR4A1 3'UTR sequence were confirmed by dual-luciferase reporter assay.

RESULTS

HIF-1α expression had no significant change after CPB modelling. Overexpression of HIF-1α improved the cardiac function of CPB rats, decreased plasma IL-6, cTnT, CK-MB, and IL-1β levels, and reduced TUNEL-positive myocardial cells. HIF-1α was enriched on the miR-124-3p promoter and promoted miR-124-3p expression. miR-124-3p bound to NR4A1 3'UTR sequence and targeted NR4A1 expression. Inhibition of miR-124-3p or overexpression of NR4A1 partially reversed the ameliorative effect of HIF-1α overexpression on myocardial injury in CPB rats.

CONCLUSION

Overexpression of HIF-1α can improve myocardial injury in CPB rats via the miR-124-3p/NR4A1 axis.

Effects of sevoflurane anesthesia and abdominal surgery on the systemic metabolome: a prospective observational study

Background

Metabolic status can be impacted by general anesthesia and surgery. However, the exact effects of general anesthesia and surgery on systemic metabolome remain unclear, which might contribute to postoperative outcomes.

Methods

Five hundred patients who underwent abdominal surgery were included. General anesthesia was mainly maintained with sevoflurane. The end-tidal sevoflurane concentration (ET_sevo) was adjusted to maintain BIS (Bispectral index) value between 40 and 60. The mean ET_sevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery was calculated for each patient. The patients were further divided into low ET_sevo group (mean − SD) and high ET_sevo group (mean + SD) to investigate the possible metabolic changes relevant to the amount of sevoflurane exposure.

Results

The mean ET_sevo of the 500 patients was 1.60% ± 0.34%. Patients with low ET_sevo (n = 55) and high ET_sevo (n = 59) were selected for metabolomic analysis (1.06% ± 0.13% vs. 2.17% ± 0.16%, P < 0.001). Sevoflurane and abdominal surgery disturbed the tricarboxylic acid cycle as identified by increased citrate and cis-aconitate levels and impacted glycometabolism as identified by increased sucrose and D-glucose levels in these 114 patients. Glutamate metabolism was also impacted by sevoflurane and abdominal surgery in all the patients. In the patients with high ET_sevo, levels of L-glutamine, pyroglutamic acid, sphinganine and L-selenocysteine after sevoflurane anesthesia and abdominal surgery were significantly higher than those of the patients with low ET_sevo, suggesting that these metabolic changes might be relevant to the amount of sevoflurane exposure.

Conclusions

Sevoflurane anesthesia and abdominal surgery can impact principal metabolic pathways in clinical patients including tricarboxylic acid cycle, glycometabolism and glutamate metabolism. This study may provide a resource data for future studies about metabolism relevant to general anaesthesia and surgeries.

Trial registration

www.chictr.org.cn. identifier: ChiCTR1800014327.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01301-0.

Cardiac Transcriptome Analysis Reveals Nr4a1 Mediated Glucose Metabolism Dysregulation in Response to High-Fat Diet

Obesity is associated with an increased risk of developing cardiovascular disease (CVD), with limited alterations in cardiac genomic characteristics known. Cardiac transcriptome analysis was conducted to profile gene signatures in high-fat diet (HFD)-induced obese mice. A total of 184 differentially expressed genes (DEGs) were identified between groups. Based on the gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs, the critical role of closely interlocked glucose metabolism was determined in HFD-induced cardiac remodeling DEGs, including Nr4a1, Fgf21, Slc2a3, Pck1, Gck, Hmgcs2, and Bpgm. Subsequently, the expression levels of these DEGs were evaluated in both the myocardium and palmitic acid (PA)-stimulated H9c2 cardiomyocytes using qPCR. Nr4a1 was highlighted according to its overexpression resulting from the HFD. Additionally, inhibition of Nr4a1 by siRNA reversed the PA-induced altered expression of glucose metabolism-related DEGs and hexokinase 2 (HK2), the rate-limiting enzyme in glycolysis, thus indicating that Nr4a1 could modulate glucose metabolism homeostasis by regulating the expression of key enzymes in glycolysis, which may subsequently influence cardiac function in obesity. Overall, we provide a comprehensive understanding of the myocardium transcript molecular framework influenced by HFD and propose Nr4a1 as a key glucose metabolism target in obesity-induced CVD.

High blood sugar levels but not diabetes mellitus significantly enhance oxaliplatin chemoresistance in patients with stage III colorectal cancer receiving adjuvant FOLFOX6 chemotherapy

Background:

The high prevalence of type 2 diabetes mellitus (DM) among patients with colorectal cancer (CRC) is becoming a serious public health concern worldwide. FOLFOX4 chemotherapy is one of the most widely used adjuvant therapies in patients with stage III colon cancer after surgical resection. However, chemotherapy resistance is associated with a poor prognosis. The prognostic impact of high blood sugar levels on oxaliplatin resistance in CRC patients is an unexplored topic.

Methods:

In total, 157 patients with stage III CRC were classified according to their fasting blood sugar level (⩾126 or <126 mg/dl). Clinicopathological features and oxaliplatin chemoresistance/survival outcome of the two groups were compared. In vitro cell proliferation assay was performed through d-(+)-glucose administration.

Results:

Multivariate analysis results revealed that high blood sugar level was a significantly independent prognostic factor of disease-free survival and overall survival (both p < 0.05), but not DM history. After metformin administration, enhanced proliferation of CRC cells (HT-29, HCT-116, SW480, and SW620) with d-(+)-glucose administration could be reversed and oxaliplatin chemosensitivity considerably increased (p < 0.05). Furthermore, phosphorylation of two glycolysis-related target proteins, SMAD3 and MYC, notably increased under high glucose concentration.

Conclusions:

Hyperglycemia can affect clinical outcomes in stage III CRC patients receiving adjuvant chemotherapy, and the mechanism underlying oxaliplatin resistance is possibly associated with increased phosphorylation of SMAD3 and MYC and upregulation of EHMT2 expression.

Nuclear receptor subfamily 4 group A member 2 inhibits activation of ERK signaling and cell growth in response to β-adrenergic stimulation in adult rat cardiomyocytes

Sustained elevation of sympathetic activity is an important contributor to pathological cardiac hypertrophy, ventricular arrhythmias, and left ventricular contractile dysfunction in chronic heart failure. The orphan nuclear receptor NR4A2 is an immediate early-response gene activated in the heart under β-adrenergic stimulation. The goal of this study was to identify the transcriptional remodeling events induced by increased NR4A2 expression in cardiomyocytes and their impact on the physiological response of those cells to sustained β-adrenergic stimulation. Treatment of adult rat ventricular myocytes with isoproterenol induced a rapid (<4 h) increase in NR4A2 levels that was accompanied by a transient (<24 h) increase in nuclear localization of the transcription factor. Adenovirus-mediated overexpression of NR4A2 to similar levels modulated the expression of genes linked to adrenoceptor signaling, calcium signaling, cell growth and proliferation and counteracted the increase in protein synthesis rate and cell surface area mediated by chronic isoproterenol stimulation. Consistent with those findings, NR4A2 overexpression also blocked the phosphorylative activation of growth-related kinases ERK1/2, Akt, and p70 S6 kinase. Prominent among the transcriptional changes induced by NR4A2 was the upregulation of the dual-specificity phosphatases DUSP2 and DUSP14, two known inhibitors of ERK1/2. Pretreatment of NR4A2-overexpressing cardiomyocytes with the DUSP inhibitor BCI [(E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one] prevented the inhibition of ERK1/2 following isoproterenol stimulation. In conclusion, our results suggest that NR4A2 acts as a novel negative feedback regulator of the β-adrenergic receptor-mediated growth response in cardiomyocytes and this at least partly through DUSP-mediated inhibition of ERK1/2 signaling.

Guidelines for experimental models of myocardial ischemia and infarction

Myocardial infarction is a prevalent major cardiovascular event that arises from myocardial ischemia with or without reperfusion, and basic and translational research is needed to better understand its underlying mechanisms and consequences for cardiac structure and function. Ischemia underlies a broad range of clinical scenarios ranging from angina to hibernation to permanent occlusion, and while reperfusion is mandatory for salvage from ischemic injury, reperfusion also inflicts injury on its own. In this consensus statement, we present recommendations for animal models of myocardial ischemia and infarction. With increasing awareness of the need for rigor and reproducibility in designing and performing scientific research to ensure validation of results, the goal of this review is to provide best practice information regarding myocardial ischemia-reperfusion and infarction models.

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