Oxidation-reduction imaging of myoglobin reveals two-phase oxidation in the reperfused myocardium.

Myocardial infarction (MI) is a serious acute cardiovascular syndrome that causes myocardial injury due to blood flow obstruction to a specific myocardial area. Under ischemic-reperfusion settings, a burst of reactive oxygen species is generated, leading to redox imbalance that could be attributed to several molecules, including myoglobin. Myoglobin is dynamic and exhibits various oxidation-reduction states that have been an early subject of attention in the food industry, specifically for meat consumers. However, rarely if ever have the myoglobin optical properties been used to measure the severity of MI. In the current study, we develop a novel imaging pipeline that integrates tissue clearing, confocal and light sheet fluorescence microscopy, combined with imaging analysis, and processing tools to investigate and characterize the oxidation-reduction states of myoglobin in the ischemic area of the cleared myocardium post-MI. Using spectral imaging, we have characterized the endogenous fluorescence of the myocardium and demonstrated that it is partly composed by fluorescence of myoglobin. Under ischemia-reperfusion experimental settings, we report that the infarcted myocardium spectral signature is similar to that of oxidized myoglobin signal that peaks 3 h post-reperfusion and decreases with cardioprotection. The infarct size assessed by oxidation-reduction imaging at 3 h post-reperfusion was correlated to the one estimated with late gadolinium enhancement MRI at 24 h post-reperfusion. In conclusion, this original work suggests that the redox state of myoglobin can be used as a promising imaging biomarker for characterizing and estimating the size of the MI during early phases of reperfusion.

Colchicine in acute myocardial infarction: cardiovascular events at 1-year follow up.

OBJECTIVE: In the COVERT-MI randomised placebo-controlled trial, oral administration of high-dose colchicine at the time of reperfusion and for 5 days in acute ST-elevated myocardial infarction did not reduce infarct size but was associated with a significant increase in left ventricular thrombus (LVT) in comparison to placebo. We aimed to assess the 1-year clinical outcomes of the study population. METHODS: This study is a follow-up analysis of the COVERT-MI study on prespecified secondary clinical endpoints at 1 year. The primary endpoint of this study was a composite of major adverse cardiovascular events (MACEs), including all-cause death, acute coronary syndromes, heart failure events, ischaemic strokes, sustained ventricular arrhythmias and acute kidney injury at 1-year follow-up. The quality of life (QOL) and the drug therapy prescription were also assessed. RESULTS: At 1 year, 192 patients (101 patients in the colchicine group, 91 in the placebo group) were followed up. Seventy-six (39.6%) MACEs were reported in the study population. There was no significant difference regarding the number of MACEs between groups: 36 (35.6%) in the colchicine group and 40 (44.1%) in the placebo group (p=0.3). There were no differences in the occurrence of ischaemic strokes between the colchicine group and the control group (3 (3%) vs 2 (2.2%), respectively, p=0.99). There was a trend towards fewer heart failure events in the colchicine group compared with the placebo group (12 (11.9%) vs 18 (19.8%), p=0.20). There was no significant difference in QOL scores at 1 year (75.8±15.7 vs 72.7±16.2 respectively, p=0.18). CONCLUSIONS: There was no significant difference between the colchicine and placebo groups at 1 year regarding MACEs, especially concerning deaths or ischaemic strokes. No excess of ischaemic adverse events was observed despite the initial increase in LVT in the colchicine group. TRIAL REGISTRATION NUMBER: NCT0315681.

TRPV1 Channels Are New Players in the Reticulum-Mitochondria Ca2+ Coupling in a Rat Cardiomyoblast Cell Line.

The Ca2+ release in microdomains formed by intercompartmental contacts, such as mitochondria-associated endoplasmic reticulum membranes (MAMs), encodes a signal that contributes to Ca2+ homeostasis and cell fate control. However, the composition and function of MAMs remain to be fully defined. Here, we focused on the transient receptor potential vanilloid 1 (TRPV1), a Ca2+-permeable ion channel and a polymodal nociceptor. We found TRPV1 channels in the reticular membrane, including some at MAMs, in a rat cardiomyoblast cell line (SV40-transformed H9c2) by Western blotting, immunostaining, cell fractionation, and proximity ligation assay. We used chemical and genetic probes to perform Ca2+ imaging in four cellular compartments: the endoplasmic reticulum (ER), cytoplasm, mitochondrial matrix, and mitochondrial surface. Our results showed that the ER Ca2+ released through TRPV1 channels is detected at the mitochondrial outer membrane and transferred to the mitochondria. Finally, we observed that prolonged TRPV1 modulation for 30 min alters the intracellular Ca2+ equilibrium and influences the MAM structure or the hypoxia/reoxygenation-induced cell death. Thus, our study provides the first evidence that TRPV1 channels contribute to MAM Ca2+ exchanges.

Combined SPT and FCS methods reveal a mechanism of RNAP II oversampling in cell nuclei.

Gene expression orchestration is a key question in fundamental and applied research. Different models for transcription regulation were proposed, yet the dynamic regulation of RNA polymerase II (RNAP II) activity remains a matter of debate. To improve our knowledge of this topic, we investigated RNAP II motility in eukaryotic cells by combining single particle tracking (SPT) and fluorescence correlation spectroscopy (FCS) techniques, to take advantage of their different sensitivities in order to analyze together slow and fast molecular movements. Thanks to calibrated samples, we developed a benchmark for quantitative analysis of molecular dynamics, to eliminate the main potential instrumental biases. We applied this workflow to study the diffusion of RPB1, the catalytic subunit of RNAP II. By a cross-analysis of FCS and SPT, we could highlight different RPB1 motility states and identifyed a stationary state, a slow diffusion state, and two different modes of subdiffusion. Interestingly, our analysis also unveiled the oversampling by RPB1 of nuclear subdomains. Based on these data, we propose a novel model of spatio-temporal transcription regulation. Altogether, our results highlight the importance of combining microscopy approaches at different time scales to get a full insight into the real complexity of molecular kinetics in cells.

Specific inflammatory profile of acute ischemic stroke patients with left atrial enlargement.

Background: The inflammatory process underlying atrial myopathy may affect the inflammatory response activated in acute ischemic stroke (AIS). Objectives: We aimed to assess whether left atrial enlargement (LAE) as a marker of atrial myopathy is associated with a different profile of circulating inflammatory markers in AIS patients. Methods: HIBISCUS-STROKE is a cohort study including anterior circulation AIS patients treated with mechanical thrombectomy following MRI. Ten circulating inflammatory markers were measured at admission and 6, 24, and 48 h after admission. LAE was defined as a left atrial volume index (LAVi) ≥34 ml/m2. A multiple logistic regression model was performed to detect an independent association between the area under the curve (AUC) of these markers and LAE. Results: We included 143 patients. Of them, 85 (59.4%) had LAE. On univariable analysis, we found that patients with LAE had higher soluble form suppression of tumorigenicity 2 (sST2), soluble tumor necrosis factor receptor I (sTNFR1), and vascular cellular adhesion molecule-1 (VCAM-1) AUC, were older, mostly female, had a higher National Institutes of Health Stroke Scale (NIHSS) score and blood glucose level at admission, had more often hypertension, and a cardioembolic source of AIS, such as atrial fibrillation, while they were less frequently current smokers and had a lower rate of tandem occlusion than patients without LAE. On multivariable analysis, we found that among circulating inflammatory markers, only high VCAM-1 (OR: 9.13, 95% CI: 3.21-25.9) and sST2 (OR: 3.40, 95% CI: 1.68-6.86) AUC remained associated with LAE. Conclusions: High VCAM-1 and sST2 levels within the first 48 h are associated with LAE in AIS patients.

Heat Shock Protein 70 Is Involved in the Efficiency of Preconditioning with Cyclosporine A in Renal Ischemia Reperfusion Injury by Modulating Mitochondrial Functions.

Cyclosporine A (CsA) preconditioning is known to target mitochondrial permeability transition pore and protect renal function after ischemia reperfusion (IR). The upregulation of heat-shock protein 70 (Hsp70) expression after CsA injection is thought to be associated with renal protection. The aim of this study was to test the effect of Hsp70 expression on kidney and mitochondria functions after IR. Mice underwent a right unilateral nephrectomy and 30 min of left renal artery clamping, performed after CsA injection and/or administration of the Hsp70 inhibitor. Histological score, plasma creatinine, mitochondrial calcium retention capacity, and oxidative phosphorylation were assessed after 24 h of reperfusion. In parallel, we used a model of hypoxia reoxygenation on HK2 cells to modulate Hsp70 expression using an SiRNA or a plasmid. We assessed cell death after 18 h of hypoxia and 4 h of reoxygenation. CsA significantly improved renal function, histological score, and mitochondrial functions compared to the ischemic group but the inhibition of Hsp70 repealed the protection afforded by CsA injection. In vitro, Hsp70 inhibition by SiRNA increased cell death. Conversely, Hsp70 overexpression protected cells from the hypoxic condition, as well as the CsA injection. We did not find a synergic association between Hsp70 expression and CsA use. We demonstrated Hsp70 could modulate mitochondrial functions to protect kidneys from IR. This pathway may be targeted by drugs to provide new therapeutics to improve renal function after IR.

SERCA2 phosphorylation at serine 663 is a key regulator of Ca2+ homeostasis in heart diseases.

Despite advances in cardioprotection, new therapeutic strategies capable of preventing ischemia-reperfusion injury of patients are still needed. Here, we discover that sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA2) phosphorylation at serine 663 is a clinical and pathophysiological event of cardiac function. Indeed, the phosphorylation level of SERCA2 at serine 663 is increased in ischemic hearts of patients and mouse. Analyses on different human cell lines indicate that preventing serine 663 phosphorylation significantly increases SERCA2 activity and protects against cell death, by counteracting cytosolic and mitochondrial Ca2+ overload. By identifying the phosphorylation level of SERCA2 at serine 663 as an essential regulator of SERCA2 activity, Ca2+ homeostasis and infarct size, these data contribute to a more comprehensive understanding of the excitation/contraction coupling of cardiomyocytes and establish the pathophysiological role and the therapeutic potential of SERCA2 modulation in acute myocardial infarction, based on the hotspot phosphorylation level of SERCA2 at serine 663 residue.

High-sensitivity calcium biosensor on the mitochondrial surface reveals that IP3R channels participate in the reticular Ca2+ leak towards mitochondria.

Genetically encoded biosensors based on fluorescent proteins (FPs) are widely used to monitor dynamics and sub-cellular spatial distribution of calcium ion (Ca2+) fluxes and their role in intracellular signaling pathways. The development of different mutations in the Ca2+-sensitive elements of the cameleon probes has allowed sensitive range of Ca2+ measurements in almost all cellular compartments. Region of the endoplasmic reticulum (ER) tethered to mitochondria, named as the mitochondrial-associated membranes (MAMs), has received an extended attention since the last 5 years. Indeed, as MAMs are essential for calcium homeostasis and mitochondrial function, molecular tools have been developed to assess quantitatively Ca2+ levels in the MAMs. However, sensitivity of the first generation Ca2+ biosensors on the surface of the outer-mitochondrial membrane (OMM) do not allow to measure µM or sub-µM changes in Ca2+ concentration which prevents to measure the native activity (unstimulated exogenously) of endogenous channels. In this study, we assembled a new ratiometric highly sensitive Ca2+ biosensor expressed on the surface of the outer-mitochondrial membrane (OMM). It allows the detection of smaller differences than the previous biosensor in or at proximity of the MAMs. Noteworthy, we demonstrated that IP3-receptors have an endogenous activity which participate to the Ca2+ leak channel on the surface of the OMM during hypoxia or when SERCA activity is blocked.

A Multimodal Cardioprotection Strategy During Cardiac Surgery: The ProCCard Study.

OBJECTIVE: The ProCCard study tested whether combining several cardioprotective interventions would reduce the myocardial and other biological and clinical damage in patients undergoing cardiac surgery. DESIGN: Prospective, randomized, controlled trial. SETTING: Multicenter tertiary care hospitals. PARTICIPANTS: 210 patients scheduled to undergo aortic valve surgery. INTERVENTIONS: A control group (standard of care) was compared to a treated group combining five perioperative cardioprotective techniques: anesthesia with sevoflurane, remote ischemic preconditioning, close intraoperative blood glucose control, moderate respiratory acidosis (pH 7.30) just before aortic unclamping (concept of the "pH paradox"), and gentle reperfusion just after aortic unclamping. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the postoperative 72-h area under the curve (AUC) for high-sensitivity cardiac troponin I (hsTnI). Secondary endpoints were biological markers and clinical events occurring during the 30 postoperative days and the prespecified subgroup analyses. The linear relationship between the 72-h AUC for hsTnI and aortic clamping time, significant in both groups (p < 0.0001), was not modified by the treatment (p = 0.57). The rate of adverse events at 30 days was identical. A non-significant reduction of the 72-h AUC for hsTnI (-24%, p = 0.15) was observed when sevoflurane was administered during cardiopulmonary bypass (46% of patients in the treated group). The incidence of postoperative renal failure was not reduced (p = 0.104). CONCLUSION: This multimodal cardioprotection has not demonstrated any biological or clinical benefit during cardiac surgery. The cardio- and reno-protective effects of sevoflurane and remote ischemic preconditioning therefore remain to be demonstrated in this context.

Isolated Mitochondria State after Myocardial Ischemia-Reperfusion Injury and Cardioprotection: Analysis by Flow Cytometry.

RATIONALE: Mitochondria are key organelles involved in cell survival and death during the acute phenomena of myocardial ischemia-reperfusion (i.e., myocardial infarction). To investigate the functions of isolated mitochondria such as calcium retention capacity, oxidative phosphorylation, and reactive oxygen species (ROS) production, already established methods are based on extramitochondrial measurements of the whole mitochondria population. OBJECTIVE: The aim of this study was to develop a reliable and well-characterized method for multiparametric analysis of isolated single mitochondrion by flow cytometry (FC) in the context of myocardial infarction. The advantage of FC is the possibility to give a simultaneous analysis of morphological parameters (side and forward scatters: SSC and FSC) for each mitochondrion, combined with intramitochondrial measurements of several biological markers, such as ROS production or membrane potential (Δφm), using specific fluorescent probes. METHODS AND RESULTS: For this study, a rat model of ischemia-reperfusion and a protective approach of post-conditioning using low reperfusion pressure was used. Thanks to the use of specific probes (NAO, MTR, TMRM, DilC1, and DHR123) combined with flow cytometry, we propose a method: (i) to identify mitochondrial populations of interest based on quality criteria (NAO/TMRM double staining); (ii) to monitor their morphological criteria, especially during swelling due to calcium overload; and (iii) to compare mitochondrial functions (membrane potential and ROS production) in different experimental groups. Applied to mitochondria from ischemic hearts, these measurements revealed that individual mitochondria are altered and that cardioprotection by low-pressure reperfusion reduces damage, as expected. CONCLUSIONS: Our results highlight FC as a reliable and sensitive method to investigate changes in mitochondrial functions and morphology in pathological conditions that disrupts their activity such as the case in ischemia-reperfusion. This methodological approach can be extended to other pathologies involving mitochondrial dysfunctions. Moreover, FC offers the possibility to work with very small amounts of isolated mitochondria, a factor that may limit the use of classical methods.

Postconditioning by Delayed Administration of Ciclosporin A: Implication for Donation after Circulatory Death (DCD).

Heart transplantation is facing a shortage of grafts. Donation after Circulatory Death (DCD) would constitute a new potential of available organs. In the present work, we aimed to evaluate whether Postconditioning (ischemic or with ciclosporin-A (CsA)) could reduce ischemia-reperfusion injury in a cardiac arrest model when applied at the start of reperfusion or after a delay. An isolated rat heart model was used as a model of DCD. Hearts were submitted to a cardiac arrest of 40 min of global warm ischemia (37 °C) followed by 3 h of 4 °C-cold preservation, then 60 min reperfusion. Hearts were randomly allocated into the following groups: control, ischemic postconditioning (POST, consisting of two episodes each of 30 s ischemia and 30 s reperfusion at the onset of reperfusion), and CsA group (CsA was perfused at 250 nM for 10 min at reperfusion). In respective subgroups, POST and CsA were applied after a delay of 3, 10, and 20 min. Necrosis was lower in CsA and POST versus controls (p < 0.01) whereas heart functions were improved (p < 0.01). However, while the POST lost its efficacy if delayed beyond 3 min of reperfusion, CsA treatment surprisingly showed a reduction of necrosis even if applied after a delay of 3 and 10 min of reperfusion (p < 0.01). This cardioprotection by delayed CsA application correlated with better functional recovery and higher mitochondrial respiratory index. Furthermore, calcium overload necessary to induce mitochondrial permeability transition pore (MPTP) opening was similar in all cardioprotection groups, suggesting a crucial role of MPTP in this delayed protection of DCD hearts.

Association of Blood Biomarkers of Inflammation With Penumbra Consumption After Mechanical Thrombectomy in Patients With Acute Ischemic Stroke.

BACKGROUND AND OBJECTIVES: The objective of this study was to assess the relationship between blood biomarkers of inflammation and lesion growth within the penumbra in acute ischemic stroke (AIS) patients treated with mechanical thrombectomy (MT). METHODS: The HIBISCUS-STROKE cohort enrolled patients admitted in the Lyon Stroke Center for an anterior circulation AIS treated with MT after brain MRI assessment. Lesion growth within the penumbra was assessed on day 6 MRI using a voxel-based nonlinear coregistration method and dichotomized into low and high according to the median value. C-reactive protein, interleukin (IL)-6, IL-8, IL-10, monocyte chemoattractant protein-1, soluble tumor necrosis factor receptor I, soluble form suppression of tumorigenicity 2 (sST2), soluble P-selectin, vascular cellular adhesion molecule-1, and matrix metalloproteinase-9 were measured in sera at 4 time points within the first 48 hours. Reperfusion was considered as successful if Thrombolysis in Cerebral Infarction score was 2b/2c/3. A multiple logistic regression model was performed to detect any association between area under the curve (AUC) of these biomarkers within the first 48 hours and a high lesion growth within the penumbra. RESULTS: Ninety patients were included. The median lesion growth within the penumbra was 2.3 (0.7-6.2) mL. On multivariable analysis, a high sST2 AUC (OR 3.77, 95% CI 1.36-10.46), a high baseline DWI volume (OR 3.65, 95% CI 1.32-10.12), and a lack of successful reperfusion (OR 0.19, 95% CI 0.04-0.92) were associated with a high lesion growth within the penumbra. When restricting analyses to patients with successful reperfusion (n = 76), a high sST2 AUC (OR 5.03, 95% CI 1.64-15.40), a high baseline DWI volume (OR 3.74, 95% CI 1.22-11.53), and a high penumbra volume (OR 3.25, 95% CI 1.10-9.57) remained associated with a high lesion growth within the penumbra. DISCUSSION: High sST2 levels within the first 48 hours are associated with a high lesion growth within the penumbra.

Mild Therapeutic Hypothermia Protects from Acute and Chronic Renal Ischemia-Reperfusion Injury in Mice by Mitigated Mitochondrial Dysfunction and Modulation of Local and Systemic Inflammation.

Renal ischemia-reperfusion (IR) injury can lead to acute kidney injury, increasing the risk of developing chronic kidney disease. We hypothesized that mild therapeutic hypothermia (mTH), 34 °C, applied during ischemia could protect the function and structure of kidneys against IR injuries in mice. In vivo bilateral renal IR led to an increase in plasma urea and acute tubular necrosis at 24 h prevented by mTH. One month after unilateral IR, kidney atrophy and fibrosis were reduced by mTH. Evaluation of mitochondrial function showed that mTH protected against IR-mediated mitochondrial dysfunction at 24 h, by preserving CRC and OX-PHOS. mTH completely abrogated the IR increase of plasmatic IL-6 and IL-10 at 24 h. Acute tissue inflammation was decreased by mTH (IL-6 and IL1-ß) in as little as 2 h. Concomitantly, mTH increased TNF-α expression at 24 h. One month after IR, mTH increased TNF-α mRNA expression, and it decreased TGF-ß mRNA expression. We showed that mTH alleviates renal dysfunction and damage through a preservation of mitochondrial function and a modulated systemic and local inflammatory response at the acute phase (2-24 h). The protective effect of mTH is maintained in the long term (1 month), as it diminished renal atrophy and fibrosis, and mitigated chronic renal inflammation.

Reassessment of mitochondrial cyclophilin D as a target for improving cardiac arrest outcomes in the era of therapeutic hypothermia.

Uncertainty exists regarding whether cyclophilin D (CypD), a mitochondrial matrix protein that plays a key role in ischemia-reperfusion injury, can be a pharmacological target for improving outcomes after cardiac arrest (CA), especially when therapeutic hypothermia is used. Using CypD knockout mice (CypD-/-), we investigated the effects of loss of CypD on short-term and medium-term outcomes after CA. CypD-/- mice or their wild-type (WT) littermates underwent either 5 minute CA followed by resuscitation with and/or without hypothermia at 33°C-34°C (targeted temperature reached within minutes after resuscitation), or a sham procedure. Brain and cardiac injury were assessed using echocardiography, neurological scores, MRI and biomarkers. Seven day survival was compared using Kaplan-Meier estimates. The rate of restoration of spontaneous circulation was significantly higher in CypD-/- mice (with shorter cardiac massage duration) than in WT mice (P < 0.05). Loss of CypD significantly attenuated CA-induced release of troponin and S100ß protein, and limited myocardial dysfunction at 150 minutes after CA. Loss of CypD combined with hypothermia led to the best neurological and MRI scores at 24 hours and highest survival rates at 7 days compared to other groups (P < 0.05). In animals successfully resuscitated, loss of CypD had no benefits on day 7 survival while hypothermia was highly protective. Pharmacological inhibition of CypD with cyclosporine A combined with hypothermia provided similar day 7 survival than loss of CypD combined with hypothermia. CypD is a viable target to improve success of cardiopulmonary resuscitation but its inhibition is unlikely to improve long-term outcomes, unless therapeutic hypothermia is associated.

Impact of Age on Systemic Inflammatory Profile of Patients With ST-Segment-Elevation Myocardial Infarction and Acute Ischemic Stroke.

BACKGROUND: Aging is associated with a chronic low-grade inflammatory state. This condition may affect the acute inflammatory response involved in ST-segment-elevation myocardial infarction (STEMI) or acute ischemic stroke (AIS). We sought to compare the profile of a set of circulating inflammatory markers between young and older patients admitted for STEMI or AIS. METHODS: HIBISCUS-STEMI (Cohort of Patients to Identify Biological and Imaging Markers of Cardiovascular Outcomes in ST Elevation Myocardial Infarction) and HIBISCUS-STROKE (Cohort of Patients to Identify Biological and Imaging Markers of Cardiovascular Outcomes in Stroke) are 2 cohort studies that enrolled patients with STEMI treated with primary percutaneous coronary intervention in the cardiac intensive care unit of Lyon and patients with AIS treated with mechanical thrombectomy in the Lyon Stroke Center, respectively from 2016 to 2019. Patients were classified as older if they were ≥65 years and as young if they were <65 years. In both cohorts, CRP (C-reactive protein), IL (interleukin)-6, IL-8, IL-10, MCP (monocyte chemoattractant protein), sTNF-RI (soluble tumor necrosis factor receptor I), sST2 (soluble form suppression of tumorigenicity 2), and VCAM-1 (vascular cellular adhesion molecule-1) were measured on serum collected at 5 time points using enzyme-linked immunosorbent assay. A multiple logistic regression model was performed to detect an association between area under the curve of circulating inflammatory markers within the first 48 hours and older age. RESULTS: A total of 260 patients with STEMI and 164 patients with AIS were included. Of them, there were 76 (29%) and 105 (64%) older patients with STEMI and AIS, respectively. Following multivariable analysis, a high area under the curve of IL-6 and sTNF-RI, a low lymphocyte count, and a high neutrophil-lymphocyte ratio at 24 hours were associated with older age in patients with STEMI and AIS. CONCLUSIONS: Older patients had higher IL-6 and sTFN-RI levels within the first 48 hours associated with a lower lymphocyte count and a higher neutrophil-lymphocyte ratio at 24 hours in both cohorts.

Cooling Uncouples Differentially ROS Production from Respiration and Ca2+ Homeostasis Dynamic in Brain and Heart Mitochondria.

Hypothermia provides an effective neuro and cardio-protection in clinical settings implying ischemia/reperfusion injury (I/R). At the onset of reperfusion, succinate-induced reactive oxygen species (ROS) production, impaired oxidative phosphorylation (OXPHOS), and decreased Ca2+ retention capacity (CRC) concur to mitochondrial damages. We explored the effects of temperature from 6 to 37 °C on OXPHOS, ROS production, and CRC, using isolated mitochondria from mouse brain and heart. Oxygen consumption and ROS production was gradually inhibited when cooling from 37 to 6 °C in brain mitochondria (BM) and heart mitochondria (HM). The decrease in ROS production was gradual in BM but steeper between 31 and 20 °C in HM. In respiring mitochondria, the gradual activation of complex II, in addition of complex I, dramatically enhanced ROS production at all temperatures without modifying respiration, likely because of ubiquinone over-reduction. Finally, CRC values were linearly increased by cooling in both BM and HM. In BM, the Ca2+ uptake rate by the mitochondrial calcium uniporter (MCU) decreased by 2.7-fold between 25 and 37 °C, but decreased by 5.7-fold between 25 and 37 °C in HM. In conclusion, mild cold (25-37 °C) exerts differential inhibitory effects by preventing ROS production, by reverse electron transfer (RET) in BM, and by reducing MCU-mediated Ca2+ uptake rate in BM and HM.

Molar Sodium Lactate Attenuates the Severity of Postcardiac Arrest Syndrome: A Preclinical Study.

OBJECTIVES: To determine whether continuous IV infusion of molar sodium lactate would limit cardiac arrest-induced neurologic injury and cardiovascular failure. DESIGN: Randomized blinded study (animal model). SETTING: University animal research facility. SUBJECTS: Twenty-four adult male "New Zealand White" rabbits. INTERVENTIONS: Anesthetized rabbits underwent 12.5 minutes of asphyxial cardiac arrest and were randomized to receive either normal saline (control group, n = 12) or molar sodium lactate (molar sodium lactate group, n = 12) at a rate of 5 mL/kg/hr during the whole 120-minute reperfusion period. MEASUREMENTS AND MAIN RESULTS: Pupillary reactivity (primary outcome), levels of S100ß protein, in vitro brain mitochondria functions, cardiovascular function, and fluid balance were assessed. Molar sodium lactate reduced brain injury, with a higher proportion of animals exhibiting pupillary reactivity to light (83% vs 25% in the CTRL group, p = 0.01) and lower S100ß protein levels (189 ± 42 vs 412 ± 63 pg/mL, p < 0.01) at the end of the protocol. Molar sodium lactate significantly prevented cardiac arrest-induced decrease in oxidative phosphorylation and mitochondrial calcium-retention capacity compared with controls. At 120 minutes of reperfusion, survival did not significantly differ between the groups (10/12, 83% in the molar sodium lactate group vs nine of 12, 75% in the control group; p > 0.99), but hemodynamics were significantly improved in the molar sodium lactate group compared with the control group (higher mean arterial pressure [49 ± 2 vs 29 ± 3 mm Hg; p < 0.05], higher cardiac output [108 ± 4 vs 58 ± 9 mL/min; p < 0.05], higher left ventricle surface shortening fraction [38% ± 3% vs 19% ± 3%; p < 0.05], and lower left ventricular end-diastolic pressure [3 ± 1 vs 8 ± 2 mm Hg; p < 0.01]). While fluid intake was similar in both groups, fluid balance was higher in control animals (11 ± 1 mL/kg) than that in molar sodium lactate-treated rabbits (1 ± 3 mL/kg; p < 0.01) due to lower diuresis. CONCLUSIONS: Molar sodium lactate was effective in limiting the severity of the postcardiac arrest syndrome. This preclinical study opens up new perspectives for the treatment of cardiac arrest.

Serum Soluble Tumor Necrosis Factor Receptors 1 and 2 Are Early Prognosis Markers After ST-Segment Elevation Myocardial Infarction.

Background: As inflammation following ST-segment elevation myocardial infarction (STEMI) is both beneficial and deleterious, there is a need to find new biomarkers of STEMI severity. Objective: We hypothesized that the circulating concentration of the soluble tumor necrosis factor α receptors 1 and 2 (sTNFR1 and sTNFR2) might predict clinical outcomes in STEMI patients. Methods: We enrolled into a prospective cohort 251 consecutive STEMI patients referred to our hospital for percutaneous coronary intervention revascularization. Blood samples were collected at five time points: admission and 4, 24, 48 h, and 1 month after admission to assess sTNFR1 and sTNFR2 serum concentrations. Patients underwent cardiac magnetic resonance imaging at 1 month. Results: sTNFR1 concentration increased at 24 h with a median of 580.5 pg/ml [95% confidence interval (CI): 534.4-645.6]. sTNFR2 increased at 48 h with a median of 2,244.0 pg/ml [95% CI: 2090.0-2,399.0]. Both sTNFR1 and sTNFR2 peak levels were correlated with infarct size and left ventricular end-diastolic volume and inversely correlated with left ventricular ejection fraction. Patients with sTNFR1 or sTNFR2 concentration above the median value were more likely to experience an adverse clinical event within 24 months after STEMI [hazards ratio (HR): 8.8, 95% CI: 4.2-18.6, p < 0.0001 for sTNFR1; HR: 6.1, 95% CI: 2.5 -10.5, p = 0.0003 for sTNFR2]. Soluble TNFR1 was an independent predictor of major adverse cardiovascular events and was more powerful than troponin I (p = 0.04 as compared to the troponin AUC). Conclusion: The circulating sTNFR1 and sTNFR2 are inflammatory markers of morphological and functional injury after STEMI. sTNFR1 appears as an early independent predictor of clinical outcomes in STEMI patients.

Effect of Colchicine on Myocardial Injury in Acute Myocardial Infarction.

BACKGROUND: Inflammation is a key factor of myocardial damage in reperfused ST-segment-elevation myocardial infarction. We hypothesized that colchicine, a potent anti-inflammatory agent, may reduce infarct size (IS) and left ventricular (LV) remodeling at the acute phase of ST-segment-elevation myocardial infarction. METHODS: In this double-blind multicenter trial, we randomly assigned patients admitted for a first episode of ST-segment-elevation myocardial infarction referred for primary percutaneous coronary intervention to receive oral colchicine (2-mg loading dose followed by 0.5 mg twice a day) or matching placebo from admission to day 5. The primary efficacy outcome was IS determined by cardiac magnetic resonance imaging at 5 days. The relative LV end-diastolic volume change at 3 months and IS at 3 months assessed by cardiac magnetic resonance imaging were among the secondary outcomes. RESULTS: We enrolled 192 patients, 101 in the colchicine group and 91 in the control group. At 5 days, the gadolinium enhancement-defined IS did not differ between the colchicine and placebo groups with a mean of 26 interquartile range (IQR) [16-44] versus 28.4 IQR [14-40] g of LV mass, respectively (P=0.87). At 3 months follow-up, there was no significant difference in LV remodeling between the colchicine and placebo groups with a +2.4% (IQR, -8.3% to 11.1%) versus -1.1% (IQR, -8.0% to 9.9%) change in LV end-diastolic volume (P=0.49). Infarct size at 3 months was also not significantly different between the colchicine and placebo groups (17 IQR [10-28] versus 18 IQR [10-27] g of LV mass, respectively; P=0.92). The incidence of gastrointestinal adverse events during the treatment period was greater with colchicine than with placebo (34% versus 11%, respectively; P=0.0002). CONCLUSIONS: In this randomized, placebo-controlled trial, oral administration of high-dose colchicine at the time of reperfusion and for 5 days did not reduce IS assessed by cardiac magnetic resonance imaging. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03156816.