Therapeutic Hypothermia Reduces the Inflammatory Response Following Ischemia/Reperfusion Injury in Rat Hearts

Mild Therapeutic Hypothermia Alleviated Myocardial Ischemia/Reperfusion Injury via Targeting SLC25A10 to Suppress Mitochondrial Apoptosis

Myocardial ischemia/reperfusion injury (MI/RI) is identified as a severe vascular emergency, and the treatment strategy of MI/RI still needs further improvement. The present study aimed to investigate the potential effects of mild therapeutic hypothermia (MTH) on MI/RI and underlying mechanisms. In ischemia/reperfusion (I/R) rats, MTH treatment significantly improved myocardial injury, attenuated myocardial infarction, and inhibited the mitochondrial apoptosis pathway. The results of proteomics identified SLC25A10 as the main target of MTH treatment. Consistently, SLC25A10 expressions in I/R rat myocardium and hypoxia and reoxygenation (H/R) cardiomyocytes were significantly suppressed, which was effectively reversed by MTH treatment. In H/R cardiomyocytes, MTH treatment significantly improved cell injury, mitochondrial dysfunction, and inhibited the mitochondrial apoptosis pathway, which were partially reversed by SLC25A10 deletion. These findings suggested that MTH treatment could protect against MI/RI by modulating SLC25A10 expression to suppress mitochondrial apoptosis pathway, providing new theoretical basis for clinical application of MTH treatment for MI/RI.

Transcriptional response to mild therapeutic hypothermia in noise-induced cochlear injury

Introduction

Prevention or treatment for acoustic injury has been met with many translational challenges, resulting in the absence of FDA-approved interventions. Localized hypothermia following noise exposure mitigates acute cochlear injury and may serve as a potential avenue for therapeutic approaches. However, the mechanisms by which hypothermia results in therapeutic improvements are poorly understood.

Methods

This study performs the transcriptomic analysis of cochleae from juvenile rats that experienced noise-induced hearing loss (NIHL) followed by hypothermia or control normothermia treatment.

Results

Differential gene expression results from RNA sequencing at 24 h post-exposure to noise suggest that NIHL alone results in increased inflammatory and immune defense responses, involving complement activation and cytokine-mediated signaling. Hypothermia treatment post-noise, in turn, may mitigate the acute inflammatory response.

Discussion

This study provides a framework for future research to optimize hypothermic intervention for ameliorating hearing loss and suggests additional pathways that could be targeted for NIHL therapeutic intervention.

Therapeutic Hypothermia Inhibits Hypoxia-Induced Cardiomyocyte Apoptosis Via the MiR-483-3p/Cdk9 Axis

Background Therapeutic hypothermia has a beneficial effect on cardiac function after acute myocardial infarction, but the exact mechanism is still unclear. Recent research has suggested that microRNAs participate in acute myocardial infarction to regulate cardiomyocyte survival. This study aimed to explore the ability of hypothermia-regulated microRNA-483-3p (miR-483-3p) to inhibit hypoxia-induced myocardial infarction. Methods and Results Primary cardiomyocytes were cultured under hypoxia at 32 °C to mimic therapeutic hypothermia, and the differentially expressed microRNAs were determined by RNA sequencing. Therapeutic hypothermia recovered hypoxia-induced increases in apoptosis, decreases in ATP levels, and decreases in miR-483-3p expression. Overexpression of miR-483-3p exhibited effects similar to those of therapeutic hypothermia on hypoxia in the treatment of cardiomyocytes to associate with maintaining the mitochondrial membrane potential, and cyclin-dependent kinase 9 (Cdk9) was identified as a target gene with downregulated expression by miR-483-3p. Knockdown of Cdk9 also promoted cardiac survival, ATP production, and mitochondrial membrane potential stability under hypoxia. In vivo, the expression of miR-483-3p and Cdk9 was tested in the cardiac tissue of the mice with acute myocardial infarction, and the expression of miR-483-3p decreased and Cdk9 increased in the region of myocardial infarction. However, miR-483-3p was overexpressed with lentivirus, which suppressed apoptosis, infarct size (miR-483-3p, 22.00±4.04% versus negative control, 28.57±5.44%, P<0.05), and Cdk9 expression to improve cardiac contractility. Conclusions MiR-483-3p antagonizes hypoxia, leading to cardiomyocyte injury by targeting Cdk9, which is a new mechanism of therapeutic hypothermia.

Circulating Galectin-3 in Patients with Cardiogenic Shock Complicating Acute Myocardial Infarction Treated with Mild Hypothermia: A Biomarker Sub-Study of the SHOCK-COOL Trial

Background: Galectin-3 (Gal-3) is considered a potential cardiovascular inflammatory marker that may provide additional risk stratification for patients with acute heart failure. It is unknown whether mild therapeutic hypothermia (MTH) impacts Gal-3 levels. Therefore, this biomarker study aimed to investigate the effect of MTH on Gal-3. Methods: In the randomized SHOCK-COOL trial, 40 patients with cardiogenic shock (CS) complicating acute myocardial infraction (AMI) were randomly assigned to the MTH (33 °C) or control group in a 1:1 ratio. Blood samples were collected on the day of admission/day 1, day 2, and day 3. Gal-3 level kinetics throughout these time points were compared between the MTH and control groups. Additionally, potential correlations between Gal-3 and clinical patient characteristics were assessed. Multiple imputations were performed to account for missing data. Results: In the control group, Gal-3 levels were significantly lower on day 3 than on day 1 (day 1 vs. day 3: 3.84 [IQR 2.04−13.3] vs. 1.79 [IQR 1.23−3.50] ng/mL; p = 0.049). Gal-3 levels were not significantly different on any day between the MTH and control groups (p for interaction = 0.242). Spearman’s rank correlation test showed no significant correlation between Gal-3 levels and sex, age, smoking, body mass index (BMI), and levels of creatine kinase-MB, creatine kinase, C-reactive protein, creatinine, and white blood cell counts (all p > 0.05). Patients with lower Gal-3 levels on the first day after admission demonstrated a higher risk of all-cause mortality at 30 days (hazard ratio, 2.67; 95% CI, 1.11−6.42; p = 0.029). In addition, Gal-3 levels on day 1 had a good predictive value for 30-day all-cause mortality with an area under the receiver operating characteristic curve of 0.696 (95% CI: 0.513−0.879), with an optimal cut-off point of less than 3651 pg/mL. Conclusions: MTH has no effect on Gal-3 levels in patients with CS complicating AMI compared to the control group. In addition, Gal-3 is a relatively stable biomarker, independent of age, sex, and BMI, and Gal-3 levels at admission might predict the risk of 30-day all-cause mortality.

Circulating Monocyte Chemoattractant Protein-1 in Patients with Cardiogenic Shock Complicating Acute Myocardial Infarction Treated with Mild Hypothermia: A Biomarker Substudy of SHOCK-COOL Trial

Background: There is evidence that monocyte chemoattractant protein-1 (MCP-1) levels reflect the intensity of the inflammatory response in patients with cardiogenic shock (CS) complicating acute myocardial infarction (AMI) and have a predictive value for clinical outcomes. However, little is known about the effect of mild therapeutic hypothermia (MTH) on the inflammatory response in patients with CS complicating AMI. Therefore, we conducted a biomarker study to investigate the effect of MTH on MCP-1 levels in patients with CS complicating AMI. Methods: In the randomized mild hypothermia in cardiogenic shock (SHOCK-COOL) trial, 40 patients with CS complicating AMI were enrolled and assigned to MTH (33 °C) for 24 h or normothermia at a 1:1 ratio. Blood samples were collected at predefined time points at the day of admission/day 1, day 2 and day 3. Differences in MCP-1 levels between and within the MTH and normothermia groups were assessed. Additionally, the association of MCP-1 levels with the risk of all-cause mortality at 30 days was analyzed. Missing data were accounted for by multiple imputation as sensitivity analyses. Results: There were differences in MCP-1 levels over time between patients in MTH and normothermia groups (P for interaction = 0.013). MCP-1 levels on day 3 were higher than on day 1 in the MTH group (day 1 vs day 3: 21.2 [interquartile range, 0.25–79.9] vs. 125.7 [interquartile range, 87.3–165.4] pg/mL; p = 0.006) and higher than in the normothermia group at day 3 (MTH 125.7 [interquartile range, 87.3–165.4] vs. normothermia 12.3 [interquartile range, 0–63.9] pg/mL; p = 0.011). Irrespective of therapy, patients with higher levels of MCP-1 at hospitalization tended to have a decreased risk of all-cause mortality at 30 days (HR, 2.61; 95% CI 0.997–6.83; p = 0.051). Conclusions: The cooling phase of MTH had no significant effect on MCP-1 levels in patients with CS complicating AMI compared to normothermic control, whereas MCP-1 levels significantly increased after rewarming. Trial registration: NCT01890317.

Genetic Polymorphisms, Gene-Gene Interactions and Neurologic Sequelae at Two Years Follow-Up in Newborns with Hypoxic-Ischemic Encephalopathy Treated with Hypothermia

Inflammation and oxidative stress after hypoxic-ischemic brain injury may be modified by genetic variability in addition to therapeutic hypothermia. The aim of our study was to evaluate the association between the polymorphisms in genes of antioxidant and inflammatory pathways in newborns treated with therapeutic hypothermia and the development of epilepsy or CP at two years follow-up. The DNA of 55 subjects was isolated from buccal swabs. Genotyping using competitive allele-specific PCR was performed for polymorphisms in antioxidant (SOD2 rs4880, CAT rs1001179, GPX1 rs1050450) and inflammatory (NLRP3 rs35829419, CARD8 rs2043211, IL1B rs1143623, IL1B rs16944, IL1B rs10716 76, TNF rs1800629) pathways. Polymorphic CARD8 rs2043211 T allele was less frequent in patients with epilepsy, but the association was not statistically significant. The interaction between CARD8 rs2043211 and IL1B rs16944 was associated with epilepsy after HIE: CARD8 rs2043211 was associated with lower epilepsy risk, but only in carriers of two normal IL1B rs16944 alleles (OR_adj = 0.03 95% CI = 0.00–0.55; p_adj = 0.019). Additionally, IL1B rs16944 was associated with higher epilepsy risk only in carriers of at least one polymorphic CARD8 rs2043211 (OR_adj = 13.33 95% CI = 1.07–166.37; p_adj = 0.044). Our results suggest that gene–gene interaction in inflammation pathways might contribute to the severity of brain injury in newborns with HIE treated with therapeutic hypothermia.

MiRNA-34c-5p protects against cerebral ischemia/reperfusion injury: involvement of anti-apoptotic and anti-inflammatory activities

MicroRNAs (miRNAs) are known as important regulators of gene expression and play important roles in diverse biological activities. However, the involvement of miRNAs in cerebral ischemia remains elusive. In the present study, using the middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury model, we found that the expression levels of miR-34c-5p were significantly reduced in MCAO rats and OGD/RP cells. Overexpression of miR-34c-5p could improve the increased brain infarction, brain water content and neurological scores in MCAO rats, as well as the abnormal expression of inflammatory cytokines (TNF-α, IL-6, COX-2, iNOS, IL-10) in OGD/RP cells. Moreover, overexpression of miR-34c-5p was found to inhibit the activity of nuclear factor-kappa B (NF-κB) by regulating the expression of nuclear receptor coactivator 1 (NCOA1), and increase the apoptotic rate of cortical neurons by inhibiting the expression of Caspase-3 and Bax and upregulating the expression of Bcl-2. Taken together, our findings demonstrated that miR-34c-5p plays an important role in cerebral ischemia/reperfusion injury, which may be mediated through inflammatory and apoptotic signaling pathways.

Cryotherapy Produces Pain Relief in Young People with Primary Dysmenorrhea

Primary dysmenorrhea is characterized as painful menstruation without associated pelvic disease and has been considered common among young people of reproductive age. Cryotherapy is a technique aimed at analgesia and anti-inflammatory action. The objective of this study was to analyze the analgesic efficacy of cryotherapy in sedentary youth with primary dysmenorrhea. Methods were included sedentary, affected by primary dysmenorrhea. The analysis of pain intensity by visual analog scale (VAS) and the Brazilian Version of the Wisconsin Brief Pain Questionnaire were used for evaluation. The participants were randomly separated into a control group (CG, n = 10) and a cryotherapy group (CryoG, n = 10). The evaluations and treatment occurred during a menstrual cycle, with three interventions, in the initial 3 days of higher menstrual flow history report. CG showed a reduction in pain when comparing the 1st with the 4th day of assessment; CryoG showed a daily reduction in VAS; for the pain questionnaire, cryotherapy showed a reduction in interference with sleep dysmenorrhea; and for all other variables, although there was no significant difference, a large effect size was observed. Cryotherapy was effective in reducing pain in women with primary dysmenorrhea, with indication of clinical improvement in daily living activities.

Mild hypothermia in rat with acute myocardial ischaemia-reperfusion injury complicating severe sepsis

Myocardial ischemia-reperfusion injury (MIRI) with concurrent severe sepsis has led to substantial mortality. Mild hypothermia (MHT) has been proved to have a therapeutic effect in either MIRI or severe sepsis, which suggests it might be beneficial for MIRI complicating severe sepsis. In this study, Sprague-Dawley rats with MIRI complicating severe sepsis were allotted in either MHT (33 ± 0.5°C) group or normothermia (NT, 37 ± 0.5°C) group; as control, rats receiving sham surgery and normal saline were kept at NT. After 2h of temperature maintenance, blood and heart tissue were acquired for detections. Lactate dehydrogenase (LDH) and MB isoenzyme of creatine kinase (CK-MB) in blood, triphenyl tetrazolium chloride and Evans blue staining, hematoxylin and eosin staining for myocardium were employed to detect myocardial damage. Tumor necrosis factor (TNF)-α and caspase-3 was performed by immunohistochemistry to exam myocardial inflammation and apoptosis. Detection of NADPH oxidase (NOX) 2 was for myocardial oxidative stress. In MHT group, systolic blood pressure was improved significantly compared with NT group. Myocardial infarct size, morphological change, LDH and CK-MB levels were attenuated compared to NT group. Moreover, less expressions of TNF-α, caspase-3 and NOX2 in MHT group were presented compared with NT group. MHT showed cardioprotection by improving cardiac dysfunction, reducing myocardial infarct size and attenuating myocardial injury, inflammation, apoptosis and oxidative stress.

Dexmedetomidine postconditioning suppresses myocardial ischemia/reperfusion injury by activating the SIRT1/mTOR axis

Myocardial ischemia/reperfusion (MI/R) triggers a complicated chain of inflammatory reactions. Dexmedetomidine (Dex) has been reported to be important in myocardial disorders. We evaluated the role of Dex in MI/R injury via the silent information regulator factor 2-related enzyme 1 (SIRT1)/mammalian target of rapamycin (mTOR) signaling pathway. First, Dex was immediately injected into rat models of MI/R injury during reperfusion. After Evans Blue-triphenyl tetrazolium chloride (TTC) and Hematoxylin-Eosin (H-E) staining, MI/R injury was observed. The extracted serum and myocardial tissues were used to detect oxidative stress and the inflammatory response. Western blot analysis was performed to evaluate MI/R autophagy and the levels of proteins associated with the SIRT1/mTOR axis. The effects of the combination of Dex and SIRT1 inhibitor EX527 on MI/R injury and autophagy were evaluated. Finally, the mechanism of Dex was tested, and autophagy levels and the levels of proteins associated with the SIRT1/mTOR signaling pathway were assessed in MI/R rats. The results of the present study suggested that Dex relieved MI/R injury, reduced cardiomyocyte apoptosis, oxidative stress and inflammatory reactions, up-regulated the SIRT1/mTOR axis and decreased overautophagy in MI/R rats. SIRT1 inhibitor EX527 attenuated the protective effects of Dex. Our study demonstrated that Dex alleviated MI/R injury by activating the SIRT1/mTOR axis. This investigation may offer new insight into the treatment of MI/R injury.

microRNA-130a-5p suppresses myocardial ischemia reperfusion injury by downregulating the HMGB2/NF-κB axis

BACKGROUND

Myocardial ischemia reperfusion injury (MIRI) is defined as tissue injury in the pathological process of progressive aggravation in ischemic myocardium after the occurrence of acute coronary artery occlusion. Research has documented the involvement of microRNAs (miRs) in MIRI. However, there is obscure information about the role of miR-130a-5p in MIRI. Herein, this study aims to investigate the effect of miR-130a-5p on MIRI.

METHODS

MIRI mouse models were established. Then, the cardiac function and hemodynamics were detected using ultrasonography and multiconductive physiological recorder. Functional assays in miR-130a-5p were adopted to test the degrees of oxidative stress, mitochondrial functions, inflammation and apoptosis. Hematoxylin and eosin (HE) staining was performed to validate the myocardial injury in mice. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was employed to assess the expression patterns of miR-130a-5p, high mobility group box (HMGB)2 and NF-κB. Then, dual-luciferase reporter gene assay was performed to elucidate the targeting relation between miR-130a-5p and HMGB2.

RESULTS

Disrupted structural arrangement in MIRI mouse models was evident from HE staining. RT-qPCR revealed that overexpressed miR-130a-5p alleviated MIRI, MIRI-induced oxidative stress and mitochondrial disorder in the mice. Next, the targeting relation between miR-130a-5p and HMGB2 was ascertained. Overexpressed HMGB2 annulled the protective effects of miR-130a-5p in MIRI mice. Additionally, miR-130a-5p targets HMGB2 to downregulate the nuclear factor kappa-B (NF-κB) axis, mitigating the inflammatory injury induced by MIRI.

CONCLUSION

Our study demonstrated that miR-130a-5p suppresses MIRI by down-regulating the HMGB2/NF-κB axis. This investigation may provide novel insights for development of MIRI treatments.

Comparison of the Protective Effect of Different Mild Therapeutic Hypothermia Temperatures on Intestinal Injury After Cardiopulmonary Resuscitation in Rats

BACKGROUND

Therapeutic temperature management (TTM) is the standard treatment protocol for unconscious post-resuscitation patients. However, there is still controversy about the ideal targeted temperature of mild hypothermia therapy. Additionally, studies about protective therapy for post-resuscitation intestinal injury are very limited. Therefore, this study was performed to explore: whether mild hypothermia therapy can exert a protective effect on post-resuscitation intestinal injury; the protective effect of different targeted temperatures on post-resuscitation intestinal injury and the ideal targeted temperature; the potential protective mechanism of mild hypothermia therapy for post-resuscitation intestinal injury.

METHODS

Ventricular fibrillation was electrically induced and untreated for 6 min while defibrillation was attempted after 8 min of cardiopulmonary resuscitation in 15 rats. After successful resuscitation, animals were randomized into three groups: control; TTM-35; TTM-33. In animals of the control group, temperature was maintained at 37 ± 0.2°C for 6 h. In animals of the two TTM groups, temperature was maintained at 33 ± 0.2°C or 35 ± 0.2°C for 6 h, respectively. During mild hypothermia therapy, intestinal microcirculation was measured at 60, 240, and 360 min after resuscitation. Animals were euthanized 6.5 h after resuscitation. The morphological changes in the intestinal tissue, systemic and local inflammatory factors, and intestinal injury markers were measured and analyzed. The tight junction proteins in the intestinal epithelium, cell-cell contact protein E-cadherin expression, myosin light chain (MLC) and myosin light chain kinase levels, and the NF-κB p65 signaling pathway were analyzed by western blotting.

RESULTS

Compared with results in the control group, mild hypothermia therapy (TTM-33 and TTM-35 groups) significantly improved post-resuscitation intestinal microcirculation and pathological scores, decreased systemic and local intestinal tissue inflammatory factor levels, inhibited the NF-κB signaling pathway and downstream MLC phosphorylation, and significantly decreased MLC phosphorylation-associated loss of intestinal tight junction proteins and E-cadherin (P < 0.05). A 33°C target temperature could exert more protective effects than 35°C on post-resuscitation intestinal injury, such as improving intestinal microcirculation, decreasing intestinal ischemia factor iFABP, and plasma endotoxin levels, inhibiting the NF-κB signaling pathway and downstream MLC phosphorylation, and suppressing the loss of intestinal tight junctions and E-cadherin (P < 0.05).

CONCLUSIONS

Mild hypothermia therapy can improve post-resuscitation intestinal injury, and a targeted temperature of 33°C may confer more benefit for mitigation of intestinal injury as compared with a targeted temperature of 35°C.

CARD8 and IL1B Polymorphisms Influence MRI Brain Patterns in Newborns with Hypoxic-Ischemic Encephalopathy Treated with Hypothermia

Inflammation and oxidative stress are recognized as important contributors of brain injury in newborns due to a perinatal hypoxic-ischemic (HI) insult. Genetic variability in these pathways could influence the response to HI and the outcome of brain injury. The aim of our study was to evaluate the impact of common single-nucleotide polymorphisms in the genes involved in inflammation and response to oxidative stress on brain injury in newborns after perinatal HI insult based on the severity and pattern of magnetic resonance imaging (MRI) findings. The DNA of 44 subjects was isolated from buccal swabs. Genotyping was performed for NLRP3 rs35829419, CARD8 rs2043211, IL1B rs16944, IL1B rs1143623, IL1B rs1071676, TNF rs1800629, CAT rs1001179, SOD2 rs4880, and GPX1 rs1050450. Polymorphism in CARD8 was found to be protective against HI brain injury detected by MRI overall findings. Polymorphisms in IL1B were associated with posterior limb of internal capsule, basal ganglia, and white matter brain patterns determined by MRI. Our results suggest a possible association between genetic variability in inflammation- and antioxidant-related pathways and the severity of brain injury after HI insult in newborns.

The Effects of Targeted Temperature Management on Oxygen-Glucose Deprivation/Reperfusion-Induced Injury and DAMP Release in Murine Primary Cardiomyocytes

Introduction. Ischemia/Reperfusion (I/R) is a primary cause of myocardial injury after acute myocardial infarction resulting in the release of damage-associated molecular patterns (DAMPs), which can induce a sterile inflammatory response in the myocardial penumbra. Targeted temperature management (TTM) after I/R has been established for neuroprotection, but the cardioprotective effect remains to be elucidated. Therefore, we investigated the effect of TTM on cell viability, immune response, and DAMP release during oxygen-glucose deprivation/reperfusion (OGD/R) in murine primary cardiomyocytes. Methods. Primary cardiomyocytes from P1-3 mice were exposed to 2, 4, or 6 hours OGD (0.2% oxygen in medium without glucose and serum) followed by 6, 12, or 24 hours simulated reperfusion (21% oxygen in complete medium). TTM at 33.5°C was initiated intra-OGD, and a control group was maintained at 37°C normoxia. Necrosis was assessed by lactate dehydrogenase (LDH) release and apoptosis by caspase-3 activation. OGD-induced DAMP secretions were assessed by Western blotting. Inducible nitric oxide synthase (iNOS), cytokines, and antiapoptotic RBM3 and CIRBP gene expressions were measured by quantitative polymerase chain reaction. Results. Increasing duration of OGD resulted in a transition from apoptotic programmed cell death to necrosis, as observed by decreasing caspase-3 cleavage and increasing LDH release. DAMP release and iNOS expression correlated with increasing necrosis and were effectively attenuated by TTM initiated during OGD. Moreover, TTM induced expression of antiapoptotic RBM3 and CIRBP. Conclusion. TTM protects the myocardium by attenuating cardiomyocyte necrosis induced by OGD and caspase-3 activation, possibly via induction of antiapoptotic RBM3 and CIRBP expressions, during reperfusion. OGD induces increased Hsp70 and CIRBP releases, but HMGB-1 is the dominant mediator of inflammation secreted by cardiomyocytes after prolonged exposure. TTM has the potential to attenuate DAMP release.

Ischemia/reperfusion injured intestinal epithelial cells cause cortical neuron death by releasing exosomal microRNAs associated with apoptosis, necroptosis, and pyroptosis

To date, there is no good evidence that intestine epithelial cells (IEC) affected by ischemia/reperfusion (I/R) injury are able to cause cortical neuron injury directly. Additionally, it remains unclear whether the neuronal damage caused by I/R injured IEC can be affected by therapeutic hypothermia (TH, 32 °C). To address these questions, we performed an oxygen–glucose deprivation (OGD) affected IEC-6-primary cortical neuron coculture system under normothermia (37 °C) or TH (32 °C) conditions. It was found that OGD caused hyperpermeability in IEC-6 cell monolayers. OGD-preconditioned IEC-6 cells caused cortical neuronal death (e.g., decreased cell viability), synaptotoxicity, and neuronal apoptosis (evidenced by increased caspase-3 expression and the number of TUNEL-positive cells), necroptosis (evidenced by increased receptor-interacting serine/threonine-protein kinase-1 [RIPK1], RIPK3 and mixed lineage kinase domain-like pseudokinase [MLKL] expression), and pyroptosis (evidenced by an increase in caspase-1, gasdermin D [GSDMD], IL-1β, IL-18, the apoptosis-associated speck-like protein containing a caspase recruitment domain [ASC], and nucleotide oligomerization domain [NOD]-like receptor [NLRP]-1 expression). TH did not affect the intestinal epithelial hyperpermeability but did attenuate OGD-induced neuronal death and synaptotoxicity. We also performed quantitative real-time PCR to quantify the genes encoding 84 exosomal microRNAs in the medium of the control-IEC-6, the control-neuron, the OGD-IEC-6 at 37 °C, the OGD-IEC-6 at 32 °C, the neuron cocultured with OGD-IEC-6 at 37 °C, and the neurons cocultured with OGD-IEC-6 at 32 °C. We found that the control IEC-6 cell s or cortical neurons are able to secrete a basal level of exosomal miRNAs in their medium. OGD significantly up-regulated the basal level of each parameter for IEC-6 cells. As compared to those of the OGD-IEC-6 cells or the control neurons, the OGD-IEC-6 cocultured neurons had significantly higher levels of 19 exosomal miRNAs related to apoptosis, necroptosis, and/or pyroptosis events. Our results identify that I/R injured intestinal epithelium cells can induce cortical neuron death via releasing paracrine mediators such as exosomal miRNAs associated with apoptosis, necroptosis, and/or pyroptosis, which can be counteracted by TH.

Therapeutic Hypothermia in STEMI

In this review article we tried to find an answer to the question, should local coronary hypothermia be a part of the early reperfusion strategy in patients with STEMI to prevent reperfusion injury, no-reflow phenomenon, and to reduce the infarct size and mortality. Hypothermia can save cardiomyocytes if achieved in a timely fashion before reperfusion. Intracoronary hypothermia can be adjunct to PCI by lessening ischemia/reperfusion injury on cardiomyocytes and reduction in infarct size. Reperfusion induced Calcium overload, generation of ROS and subsequent activation of Mitochondrial permeability transition pore (MPT) are major contributors to reperfusion injury. Hypothermia reduces calcium loading of the cell and maintains cellular energy and tissue level glucose which can scavenger ROS. Hypothermia reduces MPT activation and thus reduces infarct size. Systemic cooling trials failed to reduce infarct size, perhaps because the target temperature was not reached fast enough, and it was associated with systemic side effects. The need for rapid induction of hypothermia to <35 °C with the ethical concern of delaying reperfusion while cooling the patient and the inconsistency of endovascular cooling results lead to a belief that endovascular cooling may exceed the acceptable level of invasiveness in the context of other novels cardioprotective, regenerative and reperfusion therapies. Clinical trials showed the safety and feasibility of novel intracoronary hypothermia with rapid induction and maintenance of hypothermia using routine PCI equipment ahead of reperfusion. Two phases of cooling were applied without significant delay in the door to balloon time. Cooling of the coronary artery leads to cooling of its dependant myocardium without affecting adjacent myocardium. Heat transfer occurred by heat conduction during the occlusion phase and heat convention during the reperfusion phase. Fine-tuning of saline temperature and infusion rate helped to improve the protocol. The best duration of hypothermia before and after reperfusion is not known and needs further investigation. A balance between the undoubted cardioprotective effects of hypothermia with iatrogenic prolongation of ischemia time needs to be established. A reduction in infarct size was observed but needs to be validated with large randomized trials. Furthermore, it might be possible to augment the cardioprotective effects of intracoronary hypothermia by combination with other cardioprotective approaches such as antioxidant drugs and afterload reducing agents.

Minimal Invasive Pericardial Perfusion Model in Swine: A Translational Model for Cardiac Remodeling After Ischemia/Reperfusion Injury

Rationale

Adverse remodeling leads to heart failure after myocardial infarction (MI), with important impact on morbidity and mortality. New therapeutic approaches are needed to further improve and broaden heart failure therapy. We established a minimally invasive, reproducible pericardial irrigation model in swine, as a translational model to study the impact of temperature on adverse cardiac remodeling and its molecular mechanisms after MI.

Objective

Chronic heart failure remains a leading cause of death in western industrialized countries, with a tremendous economic impact on the health care system. Previously, many studies have investigated mechanisms to reduce infarct size after ischemia/reperfusion injury, including therapeutic hypothermia. Nonetheless, the molecular mechanisms of adverse remodeling after MI remain poorly understood. By deciphering the latter, new therapeutic strategies can be developed to not only reduce rehospitalization of heart failure patients but also reduce or prevent adverse remodeling in the first place.

Methods and Results

After 90 min of MI, a 12Fr dual lumen dialysis catheter was place into the pericardium via minimal invasive, sub-xiphoidal percutaneous puncture. We performed pericardial irrigation with cold or warm saline for 60 min in 25 female farm pigs after ischemia and reperfusion. After one week of survival the heart was harvested for further studies. After cold pericardial irrigation we observed a significant decrease of systemic body temperature measured with a rectal probe in the cold group, reflecting that the heart was chilled throughout its entire thickness. The temperature remained stable in the control group during the procedure. We did not see any difference in arrhythmia or hemodynamic stability between both groups.

Conclusion

We established a minimally invasive, reproducible and translational model of pericardial irrigation in swine. This method enables the investigation of mechanisms involved in myocardial adverse remodeling after ischemia/reperfusion injury in the future.

Therapeutic Hypothermia Protects Against Heat Stroke-Induced Arterial Hypotension via Promoting Left Ventricular Performance in Rats

We aimed to ascertain whether therapeutic hypothermia (TH) acts as cardioprotective management for heat stroke (HS). Adult male rats under general anesthesia were exposed to whole-body heating (43°C for 70 min) to induce HS. Rats with HS displayed hyperthermia (core body temperature 42°C vs. 36°C); hypotension (30 mmHg vs. 90 mmHg mean arterial blood pressure); suppressed left ventricular (LV) performance (stroke volume 52 μl/min vs. 125 μl/min), ejection fraction (0.29% vs. 0.69%), relaxation factor (72 ms vs. 12 ms), and arterial elastance (0.31 mmHg/ μl vs. 10 mmHg/ μl); increased myocardial injury markers (e.g., creatine kinase-MB: 86 U/L vs. 24 U/L, cardiac troponin I: 3.08 ng/ml vs. 0.57 ng/ml); increased myocardial oxidative stress markers (e.g., malondialdehyde: 6.52 nmol/mg vs. 1.06 nmol/mg, thiobarbituric acid-reactive substances: 29 nmol/g vs. 2 nmol/g); decreased myocardial antioxidants (e.g., superoxide dismutase: 6 unit/mg vs. 17 unit/mg, reduced glutathione: 0.64 nmol/mg vs. 2.53 nmol/mg); increased myocardial proinflammatory cytokines (e.g., tumor necrosis factor-α 3200 pg/ml vs. 1000 pg/ml, interleukin-6: 668 pg/ml vs. 102 pg/ml); and increased cardiac damage scores (2.2 vs. 0.3). TH therapy significantly reversed the following conditions: HS-induced hyperthermia (37.5°C core body temperature), hypotension (71 mmHg), suppressed LV performance (stroke volume: 97 μl/min, ejection fraction: 0.65%, relaxation factor: 39 ms, and arterial elastance: 0.99 mmHg/μl), increased myocardial injury markers (e.g., creatine kinase-MB: 37 U/L, cardiac troponin I: 1.06 ng/ml), increased myocardial oxidative stress markers (e.g., malondialdehyde: 2.68 nmol/mg, thiobarbituric acid-reactive substances: 12.3 nmol/g), decreased myocardial antioxidants (e.g., superoxide dismutase: 13.3 unit/mg, reduced glutathione: 2.71 mmol/mg), increased myocardial proinflammatory cytokines (e.g., tumor necrosis factor-α 1500 pg/ml, interleukin-6: 108 ng/ml); and increased cardiac damage scores (0.9). We thus conclude that TH protects against HS-induced arterial hypotension by promoting LV performance in rats. These results add to the literature regarding the use of TH as cardioprotective management for HS.

RBM3 and CIRP expressions in targeted temperature management treated cardiac arrest patients-A prospective single center study

BACKGROUND

Management of cardiac arrest patients includes active body temperature control and strict prevention of fever to avoid further neurological damage. Cold-shock proteins RNA-binding motif 3 (RBM3) and cold inducible RNA-binding protein (CIRP) expressions are induced in vitro in response to hypothermia and play a key role in hypothermia-induced neuroprotection.

OBJECTIVE

To measure gene expressions of RBM3, CIRP, and inflammatory biomarkers in whole blood samples from targeted temperature management (TTM)-treated post-cardiac arrest patients for the potential application as clinical biomarkers for the efficacy of TTM treatment.

METHODS

A prospective single center trial with the inclusion of 22 cardiac arrest patients who were treated with TTM (33°C for 24 hours) after ROSC was performed. RBM3, CIRP, interleukin 6 (IL-6), monocyte chemotactic protein 1 (MCP-1), and inducible nitric oxide synthase (iNOS) mRNA expressions were quantified by RT-qPCR. Serum RBM3 protein concentration was quantified using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

RBM3 mRNA expression was significantly induced in post-cardiac arrest patients in response to TTM. RBM3 mRNA was increased 2.2-fold compared to before TTM. A similar expression kinetic of 1.4-fold increase was observed for CIRP mRNA, but did not reached significancy. Serum RBM3 protein was not increased in response to TTM. IL-6 and MCP-1 expression peaked after ROSC and then significantly decreased. iNOS expression was significantly increased 24h after return of spontaneous circulation (ROSC) and TTM.

CONCLUSIONS

RBM3 is temperature regulated in patients treated with TTM after CA and ROSC. RBM3 is a possible biomarker candidate to ensure the efficacy of TTM treatment in post-cardiac arrest patients and its pharmacological induction could be a potential future intervention strategy that warrants further research.

Myocardial hypothermia increases autophagic flux, mitochondrial mass and myocardial function after ischemia-reperfusion injury

Animal studies have demonstrated beneficial effects of therapeutic hypothermia on myocardial function, yet exact mechanisms remain unclear. Impaired autophagy leads to heart failure and mitophagy is important for mitigating ischemia/reperfusion injury. This study aims to investigate whether the beneficial effects of therapeutic hypothermia are due to preserved autophagy and mitophagy. Under general anesthesia, the left anterior descending coronary artery of 19 female farm pigs was occluded for 90 minutes with consecutive reperfusion. 30 minutes after reperfusion, we performed pericardial irrigation with warm or cold saline for 60 minutes. Myocardial tissue analysis was performed one and four weeks after infarction. Therapeutic hypothermia induced a significant increase in autophagic flux, mitophagy, mitochondrial mass and function in the myocardium after infarction. Cell stress, apoptosis, inflammation as well as fibrosis were reduced, with significant preservation of systolic and diastolic function four weeks post infarction. We found similar biochemical changes in human samples undergoing open chest surgery under hypothermic conditions when compared to the warm. These results suggest that autophagic flux and mitophagy are important mechanisms implicated in cardiomyocyte recovery after myocardial infarction under hypothermic conditions. New therapeutic strategies targeting these pathways directly could lead to improvements in prevention of heart failure.

Protection against cardiac ischemia-reperfusion injury by hypothermia and by inhibition of succinate accumulation and oxidation is additive

Hypothermia induced at the onset of ischemia is a potent experimental cardioprotective strategy for myocardial infarction. The aim of our study was to determine whether the beneficial effects of hypothermia may be due to decreasing mitochondria-mediated mechanisms of damage that contribute to the pathophysiology of ischemia/reperfusion injury. New Zealand male rabbits were submitted to 30 min of myocardial ischemia with hypothermia (32 °C) induced by total liquid ventilation (TLV). Hypothermia was applied during ischemia alone (TLV group), during ischemia and reperfusion (TLV-IR group) and normothermia (Control group). In all the cases, ischemia was performed by surgical ligation of the left anterior descending coronary artery and was followed by 3 h of reperfusion before assessment of infarct size. In a parallel study, male C57BL6/J mice underwent 30 min myocardial ischemia followed by reperfusion under either normothermia (37 °C) or conventionally induced hypothermia (32 °C). In both the models, the levels of the citric acid cycle intermediate succinate, mitochondrial complex I activity were assessed at various times. The benefit of hypothermia during ischemia on infarct size was compared to inhibition of succinate accumulation and oxidation by the complex II inhibitor malonate, applied as the pro-drug dimethyl malonate under either normothermic or hypothermic conditions. Hypothermia during ischemia was cardioprotective, even when followed by normothermic reperfusion. Hypothermia during ischemia only, or during both, ischemia and reperfusion, significantly reduced infarct size (2.8 ± 0.6%, 24.2 ± 3.0% and 49.6 ± 2.6% of the area at risk, for TLV-IR, TLV and Control groups, respectively). The significant reduction of infarct size by hypothermia was neither associated with a decrease in ischemic myocardial succinate accumulation, nor with a change in its rate of oxidation at reperfusion. Similarly, dimethyl malonate infusion and hypothermia during ischemia additively reduced infarct size (4.8 ± 2.2% of risk zone) as compared to either strategy alone. Hypothermic cardioprotection is neither dependent on the inhibition of succinate accumulation during ischemia, nor of its rapid oxidation at reperfusion. The additive effect of hypothermia and dimethyl malonate on infarct size shows that they are protective by distinct mechanisms and also suggests that combining these different therapeutic approaches could further protect against ischemia/reperfusion injury during acute myocardial infarction.

Therapeutic Hypothermia for Asphyxial Out-of-Hospital Cardiac Arrest Due to Drowning: A Systematic Review of Case Series and Case Reports

The objective of this review was to summarize published evidence of the effectiveness of therapeutic hypothermia in patients with drowning-associated asphyxial out-of-hospital cardiac arrest (OHCA) and to explore any preliminary favorable factors in the management of therapeutic hypothermia to improve survival and neurological outcome. Drowning may result in asphyxial OHCA or hypothermic OHCA, but the former does not provide any potential neuroprotective effect as the latter may do. Electronic literature searches of Ovid Medline, Embase, Cochrane Library, and Scopus were performed for all years from inception to July 2016. Primary studies in the form of case reports, letters to the editor, and others with higher quality are included, but guidelines, reviews, editorials, textbook chapters, conference abstracts, and nonhuman studies are excluded. Non-English articles are excluded. Relevant studies are then deemed eligible if the drowning OHCA patient's initial temperature was above 28°C, which implies asphyxial cardiac arrest, and intentional therapeutic hypothermia was instituted. Because of the narrow scope of interest and strict definition of the condition, limited studies addressed it, and no randomized controlled trials (RCT) could be selected. Thirteen studies covering 35 patients are included. No quantitative synthesis, assessment of study quality, or assessment of bias was performed. It is conjectured that extended therapeutic hypothermia of 48-72 hours might help prevent reperfusion injury during the intermediate phase of postcardiac arrest care to benefit patients of drowning-associated asphyxial OHCA, but this finding only serves as preliminary observation for future research. No conclusive recommendation could be made regarding the duration of and the time of onset of therapeutic hypothermia. Future research should put effort on RCT, particularly the effect of extended duration of 48-72 hours. Important parameters should be reported in detail. Asphyxial and hypothermic OHCA should be differentiated.