Therapeutic mild hypothermia improves early outcomes in rats subjected to severe sepsis

Association between the severity of hypothermia and in-hospital mortality in patients with infectious diseases: The J-Point registry

Aim

Hypothermia is associated with poor prognosis in patients with sepsis. However, no studies have explored the correlation between the severity of hypothermia and prognosis.

Methods

Using data from the Japanese accidental hypothermia network registry (J-Point registry), we examined adult patients aged ≥18 years with infectious diseases whose initial body temperature was ≤35°C from April 1, 2011 to March 31, 2016, in 12 centers. Patients were divided into three groups according to their body temperature: Tertile 1 (T1) (32.0-35.0°C), Tertile 2 (T2) (28.0-31.9°C), and Tertile 3 (T3) (<28.0°C). In-hospital mortality was employed as a metric to assess outcomes. We conducted a multivariate logistic regression analysis to investigate the relationship between the three categories and the occurrence of in-hospital mortality.

Results

A total of 572 patients were registered, and 170 eligible patients were identified. Of these patients, 55 were in T1 (32.0-35.0°C), 76 in T2 (28.0-31.9°C), and 39 in T3 (<28.0°C) groups. The overall in-hospital mortality rate in accidental hypothermia (AH) patients with infectious diseases was 34.1%. The in-hospital mortality rates in the T1, T2, and T3 groups were 34.5%, 36.8%, and 28.2%, respectively. The multivariable analysis demonstrated no significant differences regarding in-hospital mortality among the three groups (T2 vs. T1, adjusted odds ratio [OR]: 1.29; 95% confidence interval [CI]: 0.58-2.89 and T3 vs. T1, adjusted OR: 0.83; 95% CI: 0.30-2.31).

Conclusion

In this multicenter retrospective observational study, hypothermia severity was not associated with in-hospital mortality in AH patients with infectious diseases.

Mild Hypothermia Alleviates CLP-induced Multiple Organ Dysfunction by Mitigating Pyroptosis Through the TLR4/NF-κB/NLRP3 Signaling Pathway

BACKGROUND

Multiple organ failure secondary to severe sepsis leads to increased morbidity and mortality and is often accompanied by inflammation and immune system dysfunction. Mild hypothermia has been shown to have anti-inflammatory properties, but whether it can exert a protective effect in cases of multiple organ failure remains unclear. Thus, in this study, we investigated the protective effect of mild hypothermia on septic multiple organ failure and the underlying mechanism for this effect.

METHOD

Sepsis was induced through the cecal ligation and puncture (CLP) method. Rats were then housed at normal (36-38°C) or mild hypothermic (32-34°C) temperature for 10 h.

RESULTS

CLP-induced effects on inflammatory cytokines and biochemical markers in serum were reversed by mild hypothermia. The pathological injury score and the expressions of pyroptosis markers, including TLR4, MyD88 and NF-κB signaling molecules, showed a similar trend. Moreover, 3 d survival of CLP rats was improved by mild hypothermia.

CONCLUSIONS

Mild hypothermia alleviated CLP-induced organ failure and the downstream effects on pyroptosis, probably through the TLR4/NF-κB/NLRP3 signaling pathway.

Low technology, mild controlled hypothermia for necrotizing enterocolitis treatment: an initiative to improve healthcare to preterm neonates

Necrotizing enterocolitis (NEC) treatment remains unchanged for years. Data suggest that mild controlled hypothermia could potentially improve NEC outcomes. Our units presented unfavourable outcomes on NEC. The aim was to assess our experience with low technology, mild controlled hypothermia on NEC outcomes, and improve preterm infants' healthcare. This was a single-center quality improvement study with retrospective cohort design at the neonatal intensive care unit in the university hospital. Forty-three preterm infants with NEC (Modified Bell's Stage II/III) were included: 19 in the control group (2015-2018) and 24 in the hypothermia group (2018-2020). The control group received standard treatment (fasting, abdominal decompression, and broad-spectrum antibiotics). The hypothermia group underwent cooling to 35.5 °C for 48 h after NEC diagnosis, along with conventional treatment. The primary outcomes are intestinal perforation, need for surgery, duration of parenteral nutrition, death, and extensive resection of the small intestine. There was no statistical difference in the NEC score. The hypothermia group required less surgery (aRR 0.40; 95% CI 0.19-0.85), presented less bowel perforation (aRR 0.39; 95% CI 0.18; 0.83), had a shorter duration of parenteral nutrition (aHR 5.28; 95% CI 1.88-14.89), did not need extensive intestinal resection, (0 vs 15.7%), and did not experience any deaths (0 vs 31.6%).Conclusions: In our experience, low technology, mild controlled hypothermia was feasible, not related to adverse effects, and effective treatment for NEC Modified Bell's Stage II/III. It avoided surgery, bowel perforation, and extensive intestinal resection; reduced mortality; and shortened parenteral nutrition duration. What is Known: • New approaches have been proposed to avoid enterocolitis incidence; however, the treatment of enterocolitis stage 2 has been the same for decades, and unfavourable outcomes remain despite conventional management. • Studies suggest that hypothermia can be an alternative to enterocolitis treatment. What is New: • Mild controlled hypothermia can be an additional practice to treat enterocolitis stage 2, is feasible, and is not related to adverse effects to preterm infants. • It can decrease surgery needs, duration of parenteral nutrition, and death and avoids extensive intestinal resection in preterm infants.

Be cool to be far: Exploiting hibernation for space exploration

In mammals, torpor/hibernation is a state that is characterized by an active reduction in metabolic rate followed by a progressive decrease in body temperature. Torpor was successfully mimicked in non-hibernators by inhibiting the activity of neurons within the brainstem region of the Raphe Pallidus, or by activating the adenosine A1 receptors in the brain. This state, called synthetic torpor, may be exploited for many medical applications, and for space exploration, providing many benefits for biological adaptation to the space environment, among which an enhanced protection from cosmic rays. As regards the use of synthetic torpor in space, to fully evaluate the degree of physiological advantage provided by this state, it is strongly advisable to move from Earth-based experiments to 'in the field' tests, possibly on board the International Space Station.

Sepsis-Induced Myocardial Dysfunction (SIMD): the Pathophysiological Mechanisms and Therapeutic Strategies Targeting Mitochondria

Sepsis is a lethal syndrome with multiple organ failure caused by an inappropriate host response to infection. Cardiac dysfunction is one of the important complications of sepsis, termed sepsis-induced myocardial dysfunction (SIMD), which is characterized by systolic and diastolic dysfunction of both sides of the heart. Mechanisms that contribute to SIMD include an excessive inflammatory response, altered circulatory, microvascular status, nitric oxide (NO) synthesis impairment, endothelial dysfunction, disorders of calcium regulation, cardiac autophagy anomaly, autonomic nervous system dysregulation, metabolic reprogramming, and mitochondrial dysfunction. The role of mitochondrial dysfunction, which is characterized by structural abnormalities, increased oxidative stress, abnormal opening of the mitochondrial permeability transition pore (mPTP), mitochondrial uncoupling, and disordered quality control systems, has been gaining increasing attention as a central player in the pathophysiology of SIMD. The disruption of homeostasis within the organism induced by mitochondrial dysfunction may also be an important aspect of SIMD development. In addition, an emerging therapy strategy targeting mitochondria, namely, metabolic resuscitation, seems promising. The current review briefly introduces the mechanism of SIMD, highlights how mitochondrial dysfunction contributes to SIMD, and discusses the role of metabolic resuscitation in the treatment of SIMD.

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.

Therapeutic Hypothermia Mitigates the Sepsis-Increased Permeability in EA. hy926 Cells by Preserving Rap1 Expression

To determine the effect and potential mechanisms of therapeutic hypothermia (TH) on the permeability of septic cells. Human EA. hy926 cells were transfected with, or without, control or ras-proximate-1 (Rap1)-specific siRNA and treated with 2 μg/mL of lipopolysaccharide (LPS). The cells were cultured in normal temperature (NT) or a temporary TH for 10 hours. The cellular permeability of each group of cells was determined by transwell permeability assay. The relative levels of Rap1, RhoA (a small GTP enzyme of the Rho family), VE-cadherin expression, and myosin light chain (MLC) phosphorylation were quantified by Western blot and immunofluorescent assays. Compared with the control group, LPS stimulation increased cellular permeability in EA. hy926 cells under an NT condition, but significantly mitigated by TH. The effect of TH decreased after Rap1 silencing. Furthermore, LPS upregulated RhoA expression and MLC phosphorylation, but reduced Rap1 and VE-cadherin expression, which were also enhanced by Rap1 silencing, but significantly mitigated by TH. Immunofluorescent analyses indicated that LPS significantly increased phosphorylated MLC, but decreased VE-cadherin expression, which were further deteriorated by Rap1 silencing, but significantly mitigated by TH in EA. hy926 cells. TH significantly mitigated the sepsis-increased permeability of EA. hy926 cells by enhancing the Rap1 expression to attenuate the RhoA/MLC signaling.

Investigation of myocardial protection during pediatric CPB: Practical experience in 100 Chinese hospitals

Many measures have been proposed for myocardial protection in pediatric congenital heart surgeries, but little data is available for China. This study investigates myocardial protection strategies in pediatric cardiopulmonary bypass (CPB) throughout China. Online questionnaires were delivered to 100 hospitals in 27 provinces. The number of yearly on-pump pediatric cardiovascular surgeries in these hospitals varied greatly. About 91.0% of respondents believe that each surgery should have at least two perfusionists, while only 64.0% of hospitals actually met this requirement. For pediatric patients, crystalloid cardioplegia was more prevalent than blood-based cardioplegia. Histidine-tryptophan-ketoglutarate solution and St. Thomas crystalloid solution were dominant among crystalloid cardioplegia. Del Nido cardioplegia and St. Thomas blood-based cardioplegia ranked the top two in the popularity of blood-based cardioplegia. Dosages varied among different kinds of cardioplegia. In the choice of different cardioplegia, perfusionists mainly focused on myocardial protective effect and cost. Hypothermia of cardioplegia solution was maintained by ice buckets in 3/4 of the hospitals in this survey. In conclusion, the essence of myocardial protection management during pediatric CPB was cardiac arrest induced by cardioplegia under systemic hypothermia. However, there is no uniform standard for the type of cardioplegia, or dosages. Therefore, well-designed multicenter randomized controlled trials are warranted to provide tangible evidence for myocardial protection of cardioplegia in pediatric CPB.

Protective effects of mild hypothermia against hepatic injury in rats with acute liver failure

INTRODUCTION AND OBJECTIVES

Acute liver failure (ALF) is a severe disease which is associated with a high mortality rate. As mild hypothermia has been shown to have protective effects on the brain, this study aimed to determine whether it also provides protection to the liver in rats with ALF and to explore its underlying mechanism.

MATERIALS AND METHODS

In total, 72 rats were divided into 3 groups: control group (CG, treated with normal saline), normothermia group (NG, treated with d-galactosamine and lipopolysaccharide; d-GalN/LPS), and mild hypothermia group (MHG, treated with d-GalN/LPS and kept in a state of mild hypothermia, defined as an anal temperature of 32-35°C). The rats were examined at 4, 8, and 12h after treatment.

RESULTS

Mild hypothermia treatment significantly reduced serum alanine transaminase and aspartate transaminase levels and improved the liver condition of rats with d-GalN/LPS-induced ALF at 12h. Serum tumor necrosis factor-alpha levels were significantly lower in the MHG than in the NG at 4h, but no significant differences were observed in the interleukin-10 levels between the NG and MHG at any time. The serum and hepatic levels of high mobility group box 1 were significantly lower in the MHG than in the NG at 8 and 12h. The protein expression levels of cytochrome C and cleaved-caspase 3 in hepatic tissues were significantly lower in the MHG than in the NG at 8h.

CONCLUSION

Mild hypothermia improved the liver conditions of rats with ALF via its anti-inflammatory and anti-apoptotic effects.

Metabolic Resuscitation Strategies to Prevent Organ Dysfunction in Sepsis

Significance: Sepsis is the main cause of death among patients admitted to the intensive care unit. As current treatment is limited to antimicrobial therapy and supportive care, mortality remains high, which warrants efforts to find novel therapies. Recent Advances: Mitochondrial dysfunction is emerging as a key process in the induction of organ dysfunction during sepsis, and metabolic resuscitation might reveal to be a novel cornerstone in the treatment of sepsis. Critical Issues: Here, we review novel strategies to maintain organ function in sepsis by precluding mitochondrial dysfunction by lowering energetic demand to allow preservation of adenosine triphosphate-levels, while reducing free radical generation. As the most common strategy to suppress metabolism, that is, cooling, does not reveal unequivocal beneficial effects and may even increase mortality, caloric restriction or modulation of energy-sensing pathways (i.e., sirtuins and AMP-activated protein kinase) may offer safe alternatives. Similar effects may be offered when mimicking hibernation by hydrogen sulfide (H₂S). In addition H₂S may also confer beneficial effects through upregulation of antioxidant mechanisms, similar to the other gasotransmitters nitric oxide and carbon monoxide, which display antioxidant and anti-inflammatory effects in sepsis. In addition, oxidative stress may be averted by systemic or mitochondria-targeted antioxidants, of which a wide range are able to lower inflammation, as well as reduce organ dysfunction and mortality from sepsis. Future Directions: Mitochondrial dysfunction plays a key role in the pathophysiology of sepsis. As a consequence, metabolic resuscitation might reveal to be a novel cornerstone in the treatment of sepsis.