Hypothermia downregulates inflammation but enhances IL-6 secretion by stimulated endothelial cells

Mild therapeutic hypothermia protects against inflammatory and proapoptotic processes in the rat model of cochlear implant trauma

OBJECTIVE

Mild therapeutic hypothermia (MTH) has been demonstrated to prevent residual hearing loss from surgical trauma associated with cochlear implant (CI) insertion. Here, we aimed to characterize the mechanisms of MTH-induced hearing preservation in CI in a well-established preclinical rodent model.

APPROACH

Rats were divided into four experimental conditions: MTH-treated and implanted cochleae, cochleae implanted under normothermic conditions, MTH only cochleae and un-operated cochleae (controls). Auditory brainstem responses (ABRs) were recorded at different time points (up to 84 days) to confirm long-term protection and safety of MTH locally applied to the cochlea for 20 min before and after implantation. Transcriptome sequencing profiling was performed on cochleae harvested 24 h post CI and MTH treatment to investigate the potential beneficial effects and underlying active gene expression pathways targeted by the temperature management.

RESULTS

MTH treatment preserved residual hearing up to 3 months following CI when compared to the normothermic CI group. In addition, MTH applied locally to the cochleae using our surgical approach was safe and did not affect hearing in the long-term. Results of RNA sequencing analysis highlight positive modulation of signaling pathways and gene expression associated with an activation of cellular inflammatory and immune responses against the mechanical damage caused by electrode insertion.

SIGNIFICANCE

These data suggest that multiple and possibly independent molecular pathways play a role in the protection of residual hearing provided by MTH against the trauma of cochlear implantation.

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.

Therapeutic hypothermia augments the restorative effects of PKC-β and Nox2 inhibition on an in vitro model of human blood-brain barrier

To investigate whether therapeutic hypothermia augments the restorative impact of protein kinase C-β (PKC-β) and Nox2 inhibition on an in vitro model of human blood-brain barrier (BBB). Cells cultured in normoglycaemic (5.5 mM) or hyperglycaemic (25 mM, 6 to 120 h) conditions were treated with therapeutic hypothermia (35 °C) in the absence or presence of a PKC-β inhibitor (LY333531, 0.05 μM) or a Nox2 inhibitor (gp91ds-tat, 50 μM). BBB was established by co-culture of human brain microvascular endothelial cells (HBMECs) with astrocytes (HAs) and pericytes. BBB integrity and function were assessed via transendothelial electrical resistance (TEER) and paracellular flux of sodium fluorescein (NaF, 376 Da). Nox activity (lucigenin assay), superoxide anion production (cytochrome-C reduction assay), cellular proliferative capacity (wound scratch assay) and actin cytoskeletal formation (rhodamine-phalloidin staining) were assessed both in HBMECs and HAs using the specific methodologies indicated in brackets. Therapeutic hypothermia augmented the protective effects of PKC-β or Nox2 inhibition on BBB integrity and function in experimental setting of hyperglycaemia, as evidenced by increases in TEER and concomitant decreases in paracellular flux of NaF. The combinatory approaches were more effective in repairing physical damage exerted on HBMEC and HA monolayers by wound scratch and in decreasing Nox activity and superoxide anion production compared to sole treatment regimen with either agent. Similarly, the combinatory approaches were more effective in suppressing actin stress fibre formation and maintaining normal cytoskeletal structure. Therapeutic hypothermia augments the cerebral barrier-restorative capacity of agents specifically targeting PKC-β or Nox2 pathways.

Effects of cryotherapy on the regeneration process and muscular mechanical properties after lacerative injury model

Cryotherapy is a therapeutic modality widely used for the treatment of muscle injuries to control pain and inflammatory processes. This study aimed to investigate the effects of cryotherapy on the inflammatory and oxidative stress parameters and mechanical properties of, and pain in, the skeletal muscles of rats with lacerative muscle injury. The rats were anesthetized with 4% isoflurane and subjected to gastrocnemius muscle laceration injury. After injury, all animals in the intervention groups received cryotherapy treatment for 20 minutes using plastic bags containing crushed ice. The protocol comprised three daily applications at 3-hour intervals on the day of injury, with reapplication 24 hours later. Seventy-two male Wistar rats were divided into three groups: sham, muscle injury (MI), and MI + cryotherapy (MI + cryo). Muscle mechanical properties were analyzed by mechanical tensile testing on day 7 after injury. The MI + cryo group showed reduced TNF-α, IFN-γ, and IL1β levels; elevated IL4, IL6, and IL10 levels; reduced oxidant production and carbonyl levels; and elevated sulfhydryl contents. Animals that underwent tissue cooling showed superoxide dismutase activity and glutathione levels close to those of the animals in the sham group. The MI and MI + cryo groups showed reduced values of the evaluated mechanical properties and lower mechanical thresholds compared to those of the animals from the sham group. Our results demonstrated that the proposed cryotherapy protocol reduced the inflammatory process and controlled oxidative stress but did not reverse the changes in the mechanical properties of muscle tissues or provide analgesic effects within the time frame analyzed.

Effects of Cryotherapy Applied at Different Temperatures on Inflammatory Pain During the Acute Phase of Arthritis in Rats

OBJECTIVE

The biological mechanisms of cryotherapy for managing acute pain remain unclear. Additionally, it is unknown whether the effectiveness of cryotherapy depends on the applied temperature. This study aimed to clarify the biological effects of cryotherapy and to examine the therapeutic effects of cryotherapy applied at different temperatures in rats.

METHODS

This was an experimental study using a rat knee joint arthritis model. Thirty-five Wistar rats were randomly divided into arthritis (AR), arthritis with 5°C cryotherapy (CR-5), arthritis with 10°C cryotherapy (CR-10), and sham-arthritis control (CON) groups. Arthritis was induced by injecting a mixture of kaolin/carrageenan into the right knee joint. Cryotherapy was applied for 7 days starting the day after injection by immersing the right knee joint in 5°C or 10°C water. Joint transverse diameter, pressure pain threshold, and pain-related behaviors were assessed for 7 days. The number of CD68-positive cells in the knee joint and the expression of calcitonin gene-related peptide in the spinal dorsal horn 8 days after injection were analyzed by immunohistochemical staining.

RESULTS

Improvements in transverse diameter, pressure pain threshold, and pain-related behaviors were observed in the CR-5 and CR-10 groups on the 3rd day compared with the AR group. The number of CD68-positive cells and the expression of calcitonin gene-related peptide in the CR-5 and CR-10 groups were significantly decreased compared with the AR group. There were no significant differences in all results between the CR-5 and CR-10 groups.

CONCLUSIONS

Cryotherapy can ameliorate inflammatory pain through reduction of synovium and central sensitization. Additionally, the effects of cryotherapy lower than 10°C are observed independent of applied temperature.

IMPACT

Cryotherapy may be beneficial as a physical therapy modality for pain and swelling management in the acute phase of inflammation. Translational human study is needed to determine the effective cryotherapy temperature for the inflammatory pain.

Effects of xenon gas on human airway epithelial cells during hyperoxia and hypothermia

BACKGROUND

Hypothermia with xenon gas has been used to reduce brain injury and disability rate after perinatal hypoxia-ischemia. We evaluated xenon gas therapy effects in an in vitro model with or without hypothermia on cultured human airway epithelial cells (Calu-3).

METHODS

Calu-3 monolayers were grown at an air-liquid interface and exposed to one of the following conditions: 1) 21% FiO2 at 37°C (control); 2) 45% FiO2 and 50% xenon at 37°C; 3) 21% FiO2 and 50% xenon at 32°C; 4) 45% FiO2 and 50% xenon at 32°C for 24 hours. Transepithelial resistance (TER) measurements were performed and apical surface fluids were collected and assayed for total protein, IL-6, and IL-8. Three monolayers were used for immunofluorescence localization of zonula occludens-1 (ZO-1). The data were analyzed by one-way ANOVA.

RESULTS

TER decreased at 24 hours in all treatment groups. Xenon with hyperoxia and hypothermia resulted in greatest decrease in TER compared with other groups. Immunofluorescence localization of ZO-1 (XY) showed reduced density of ZO-1 rings and incomplete ring-like staining in the 45% FiO2- 50% xenon group at 32°C compared with other groups. Secretion of total protein was not different among groups. Secretion of IL-6 in 21% FiO2 with xenon group at 32°C was less than that of the control group. The secretion of IL-8 in 45% FiO2 with xenon at 32°C was greater than that of other groups.

CONCLUSION

Hyperoxia and hypothermia result in detrimental epithelial cell function and inflammation over 24-hour exposure. Xenon gas did not affect cell function or reduce inflammation.

Akt1-mediated CPR cooling protection targets regulators of metabolism, inflammation and contractile function in mouse cardiac arrest

Therapeutic hypothermia initiated during cardiopulmonary resuscitation (CPR) in pre-clinical studies appears to be highly protective against sudden cardiac arrest injury. Given the challenges to implementing CPR cooling clinically, insights into its critical mechanisms of protection could guide development of new CPR drugs that mimic hypothermia effects without the need for physical cooling. Here, we used Akt1-deficient mice that lose CPR hypothermia protection to identify hypothermia targets. Adult female C57BL/6 mice (Akt1^+/+ and Akt1^+/-) underwent 8 min of KCl-induced asystolic arrest and were randomized to receive hypothermia (30 ± 0.5°C) or normothermia. Hypothermia was initiated during CPR and extended for 1 h after resuscitation. Neurologically scored survival was measured at 72 h. Other outcomes included mean arterial pressure and target measures in heart and brain related to contractile function, glucose utilization and inflammation. Compared to northothermia, hypothermia improved both 2h mean arterial pressure and 72h neurologically intact survival in Akt1^+/+ mice but not in Akt1^+/- mice. In Akt1^+/+ mice, hypothermia increased Akt and GSK3β phosphorylation, pyruvate dehydrogenase activation, and NAD⁺ and ATP production while decreasing IκBα degradation and NF-κB activity in both heart and brain at 30 min after CPR. It also increased phospholamban phosphorylation in heart tissue. Further, hypothermia reduced metabolic and inflammatory blood markers lactate and Pre-B cell Colony Enhancing Factor. Despite hypothermia treatment, all these effects were reversed in Akt1^+/- mice. Taken together, drugs that target Akt1 and its effectors may have the potential to mimic hypothermia-like protection to improve sudden cardiac arrest survival when administered during CPR.

Local ice cryotherapy decreases synovial interleukin 6, interleukin 1β, vascular endothelial growth factor, prostaglandin-E2, and nuclear factor kappa B p65 in human knee arthritis: a controlled study

Background

The aim of this study was to assess the anti-inflammatory effects of local cryotherapy in human non-septic knee arthritis.

Methods

In the phase I of the study, patients were randomized to receive either ice (30 min; N = 16) or cold CO₂ (2 min; N = 16) applied twice during 1 day at an 8-h interval on the arthritic knee. In phase II, 16 other ice-treated arthritic knees according to the same protocol were compared to the contralateral non-treated arthritic knees (N = 16). The synovial fluid was analyzed just before the first cold application, then 24 h later. IL-6, IL-1β, TNF-α, IL-17A, VEGF, NF-kB-p65 protein, and PG-E2 levels were measured in the synovial fluid and compared before/after the two cold applications.

Results

Forty-seven patients were included (17 gouts, 11 calcium pyrophosphate deposition diseases, 13 rheumatoid arthritides, 6 spondyloarthritides). Local ice cryotherapy significantly reduced the IL-6, IL-1β, VEGF, NF-kB-p65, and PG-E2 synovial levels, especially in the microcrystal-induced arthritis subgroup, while only phosphorylated NF-kB-p65 significantly decreased in rheumatoid arthritis and spondyloarthritis patients. Cold CO₂ only reduced the synovial VEGF levels. In the phase II of the study, the synovial PG-E2 was significantly reduced in ice-treated knees, while it significantly increased in the corresponding contralateral non-treated arthritic knees, with a significant inter-class effect size (mean difference − 1329 [− 2232; − 426] pg/mL; N = 12).

Conclusions

These results suggest that local ice cryotherapy reduces IL-6, IL-1β, and VEGF synovial protein levels, mainly in microcrystal-induced arthritis, and potentially through NF-kB and PG-E2-dependent mechanisms.

Trial registration

Clinicaltrials.gov, NCT03850392—registered February 20, 2019—retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1965-0) contains supplementary material, which is available to authorized users.

Effect of cooling on lung secretory phospholipase A2 activity in vitro, ex vivo, and in vivo

Hypothermia can modify surfactant composition and function. Secretory phospholipase A2 (sPLA2) hydrolyses surfactant phospholipids and is important in the pathobiology of several critical respiratory disorders. We hypothesize that sPLA2 activity might be influenced by the temperature partially explaining surfactant changes. This study aims to evaluate comprehensively the effect of hypothermia on sPLA2 activity. We measured sPLA2 activity at different temperatures, alone or combined with bile acids, in vitro (incubating human recombinant sPLA2-IIA and porcine sPLA2-IB), ex vivo (by cooling bronchoalveolar lavage samples from neonates with respiratory distress syndrome or no lung disease), and in vivo (using lavage samples obtained before and after 72 h of whole body cooling in neonates with hypoxic-ischemic encephalopathy). We also measured concentrations of various sPLA2 subtypes and natural sPLA2 inhibitors in in vivo cooled samples. Results were corrected for protein content and dilution. In vitro cooling did not show any effect of hypothermia on sPLA2. Ex vivo cooling did not alter total sPLA2 activity, and the addition of bile acids increased sPLA2 activity irrespective of the temperature and the type of sampled patient. In vivo hypothermia reduced median sPLA2 activity from 16.6 [15.2–106.7] IU/mg to 3.3 [2.7–8.5] IU/mg ( P = 0.026) and mean sPLA2-IIA from 1.1 (0.8) pg/μg to 0.6 (0.4) pg/μg ( P = 0.047), whereas dioleylphosphatidylglycerol increased from 8.3 (3.9)% to 12.8 (5.1)% ( P = 0.02). Whole body hypothermia decreases in vivo global sPLA2 activity in bronchoalveolar lavage fluids through the reduction of sPLA2-IIA and increment of dioleylphosphatidylglycerol. This effect is absent during in vitro or ex vivo hypothermia.

Direct Splanchnic Perfusion Safely Avoids Deep Hypothermia

Deep hypothermia for the operative correction of congenital cardiac lesions protects hypoperfused organs, mostly because of its effect on lowering metabolic demand and oxygen requirement. Deleterious cerebral and extracranial side effects of deep hypothermia itself calls for a reexamination of the therapeutic value of hypothermia, and has led to the development of alternative perfusion strategies. Here we describe the potential advantages of milder hypothermia over deep hypothermia and our method of a practical and reproducible implementation of multisite perfusion under mild hypothermia (32°C).

Fas-ligand and interleukin-6 in the cerebrospinal fluid are early predictors of hypoxic-ischemic encephalopathy and long-term outcomes after birth asphyxia in term infants

BACKGROUND

Cerebral ischemia generates neuroinflammation that can induce neural cell death. This cohort study assessed whether Fas-ligand (FasL) and interleukin (IL)-6 levels in the cerebrospinal fluid (CSF) after hypoxic-ischemic encephalopathy (HIE) can serve as biomarkers of hypoxic brain injury in neonates.

METHODS

Term infants (> 37-week gestational age) who were admitted to the neonatal intensive care unit of Karolinska University Hospital in years 2002 to 2004 with perinatal asphyxia were enrolled prospectively. Control infants without brain pathology underwent lumbar puncture for suspected infection. FasL and IL-6 levels were measured in the CSF, by enzyme-linked immunosorbent assays. All patients underwent neurological assessment at 18 months. HIE was classified as mild, moderate, or severe (HIE I-III). Adverse neurological outcome at 18 months was defined as a mental developmental index < 85, deafness, blindness, cerebral palsy, or seizure disorder.

RESULTS

Of the 44 HIE patients, 14, 16, and 14 had HIE-I, HIE-II, and HIE-III, respectively. HIE-II and HIE-III patients had higher FasL and IL-6 levels than HIE-I patients and the 20 controls (all p < 0.0001). Patients with adverse outcomes had higher FasL and IL-6 levels than patients with normal outcomes and controls (both p < 0.0001). On receiver-operator curve analyses, FasL and IL-6 (alone and together) were highly predictive of HIE grade and outcome (areas under the curve range 0.86-0.94) and showed high sensitivity (66.7-100%). These biomarkers performed better than cord blood pH (areas under the curve: HIE grade = 0.80, adverse outcomes = 0.86).

CONCLUSION

CSF biomarkers FasL and IL-6 predicted severity of encephalopathy and long-term outcomes in post-asphyxiated infants better than a standard biomarker.

Impact of Hypothermia and Oxygen Deprivation on the Cytoskeleton in Organ Preservation Models

Ischemia reperfusion (IR) lesions are an unavoidable consequence of organ transplantation. Researching new therapeutics against these lesions requires the definition of early mechanisms. The cytoskeleton is composed of 3 types of filaments: microfilaments, intermediate filaments, and microtubules. We aimed to characterize the influence of preservation on their phenotype. In an in vitro model using primary human endothelial cells reproducing the conditions of organ preservation, two aspects were explored: (a) the impact of IR and cold ischemia time on each filament type, evaluating the roles of temperature, solution, and oxygen; and (b) the potential of cytoskeleton-mediated therapy to alleviate cell death. Results showed that intermediary filaments were unaffected, while microfilaments showed radical changes with disappearance of the structure replaced by a disorganized array of nodules; moreover, microtubules almost completely disappeared with time. Furthermore, temperature, and not oxygen deprivation or the solution, was the determining factor of the cytoskeleton's loss of integrity during preservation. Finally, pharmaceutical intervention could indeed preserve fiber structure but did not alter survival. Our work shows that improvement of preservation must include a more adapted temperature before considering oxygen, as it could profoundly improve cytoskeleton organization and thus cell fate. This highlights the importance of this structure for the development of new therapeutics and the definition of graft quality biomarkers.

Deep hypothermic circulatory arrest or tepid regional cerebral perfusion: impact on haemodynamics and myocardial integrity in a randomized experimental trial

OBJECTIVES

Organ protective management during aortic arch surgery comprises deep hypothermic (18°C) circulatory arrest (DHCA), or moderate hypothermia (28°C/ 'tepid') with regional cerebral perfusion (TRCP). The aim of this experimental study was to evaluate the effect of distinct organ protective management on hemodynamic performance and myocardial integrity.

METHODS

Ten male piglets were randomized to group DHCA (n = 5) or TRCP (n = 5) group and operated on cardiopulmonary bypass (CPB) with 60 min of aortic cross-clamping. Blood gas analysis was performed throughout the experiment. Haemodynamic assessment was performed using a thermodilution technique before and after CPB. Myocardial biopsies were taken 2 h after CPB and evaluated using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labelling assay and western blot analysis.

RESULTS

At reperfusion, levels of central venous saturation were significantly higher (P = 0.016) and levels of lactate significantly lower (P = 0.029) in the DHCA group. After CPB, thermodilution measurements revealed higher stroke volume and lower peripheral resistance in the TRCP group (P = 0.012 and 0.037). At the end of the experiment, no significant differences regarding laboratory and haemodynamic parameters were evident. All specimens showed enrichment of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labelling-positive cells exclusively at the left ventricular subendocardium with no difference between groups and equal concentrations of cyclo-oxygenase-2.

CONCLUSIONS

TRCP is associated with decreased peripheral resistance and higher stroke volume immediately after CPB. However, this beneficial effect is contrasted by signs of lower body hypoperfusion, which is expressed by lower central venous saturations and higher lactate levels. Distinct strategies of organ protection did not seem to affect apoptotic/necrotic and inflammatory changes in the left ventricular myocardium.

Local cryotherapy improves adjuvant-induced arthritis through down-regulation of IL-6 / IL-17 pathway but independently of TNFα

OBJECTIVES

Local cryotherapy is widely and empirically used in the adjuvant setting in rheumatoid arthritis treatment, however its own therapeutic and anti-inflammatory effects are poorly characterized. We aimed to evaluate the effects of local cryotherapy on local and systemic inflammation in Adjuvant-induced arthritis, a murine model of rheumatoid arthritis.

METHODS

The effects of mild hypothermia (30°C for 2 hours) on cytokine protein levels (Multiplex/ELISA) were evaluated in vitro in cultured rat adjuvant-induced arthritis patellae. In vivo, local cryotherapy was applied twice a day for 14 days in arthritic rats (ice: n = 10, cold gas: n = 9, non-treated: n = 10). At day 24 after the induction of arthritis, cytokine expression levels were measured in grinded hind paws (Q-RT-PCR) and in the plasma (Multiplex/ELISA).

RESULTS

In vitro, punctual mild hypothermia down-regulated IL-6 protein expression. In vivo, ice showed a better efficacy profile on the arthritis score and joint swelling and was better tolerated, while cold gas induced a biphasic response profile with initial, transient arthritis worsening. Local cryotherapy also exerted local and systemic anti-inflammatory effects, both at the gene and the protein levels: IL-6, IL-17A and IL-1β gene expression levels were significantly down-regulated in hind paws. Both techniques decreased plasma IL-17A while ice decreased plasma IL-6 protein levels. By contrast, we observed no effect on local/systemic TNF-α pathway.

CONCLUSIONS

We demonstrated for the first time that sub-chronically applied local cryotherapy (ice and cold gas) is an effective and well-tolerated treatment in adjuvant-induced arthritis. Furthermore, we provided novel insights into the cytokine pathways involved in Local cryotherapy's local and systemic anti-inflammatory effects, which were mainly IL-6/IL-17A-driven and TNF-α independent in this model.

miR-146a, miR-146b, and miR-155 increase expression of IL-6 and IL-8 and support HSP10 in an In vitro sepsis model

microRNAs (miRNAs) play an essential role in inflammation processes including sepsis. This study aimed to identify miRNAs as candidates for therapies that are involved in the innate immune response and to assess their potential functions in the activation of the endothelium. We stimulated THP-1 monocytes with 10 ng/ml LPS for 4 h and used the supernatant for the stimulation of human umbilical vein endothelial cells (HUVEC) or human pulmonary microvascular endothelial cells (HPMEC) for 16 h. miRNA array analysis (of 1,891 miRNAs) identified a 1.5-fold upregulation of miR-146a, miR-146b, and miR-155 in stimulated endothelial cells. HUVEC were transfected with miRNA inhibitors for miR-146a, miR-146b, and miR-155 to investigate the function of these miRNAs in endothelial inflammatory pathways. Inhibition of miR-146a resulted in a diminished release of interleukin (IL)-6 and IL-8 by respective 68% and 55% (P<0.001). Inhibition of miR-146b reduced the expression of IL-6 by 49% (P<0.001). Inhibition of miR-155 reduced the expression of IL-6 and IL-8 by respective 31% (P<0.001) and 14%. The inhibition of miR-146a, miR-146b, and miR-155 reduced the release of HSP10 by 50%, 35%, and 69% (P<0.05), respectively, but did not influence the expression of HSP27 or TXA2. In conclusion, miR-146a, miR-146b, and miR-155 are exerting anti-inflammatory properties by down-regulating IL-6 and IL-8, and influencing the expression of HSP10 in the activated endothelium. We provide evidence for the central role of selected miRNAs in sepsis and their use in the development of small interfering RNA therapeutics to target immune cells and sepsis pathways.

Inflammatory cytokine response and reduced heart rate variability in newborns with hypoxic-ischemic encephalopathy

OBJECTIVE

To determine whether systemic inflammation-modulating cytokine expression is related to heart rate variability (HRV) in newborns with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

The data from 30 newborns with HIE were analyzed. Cytokine levels (IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, IL-1β, TNF-α, IFN-λ) were measured either at 24 h of cooling (n=5), 72 h of cooling (n=4) or at both timepoints (n=21). The following HRV metrics were quantified in the time domain: alpha_S, alpha_L, root mean square (RMS) at short time scales (RMS_S), RMS at long time scales (RMS_L), while low-frequency power (LF) and high-frequency power (HF) were quantified in the frequency domain. The relationships between HRV metrics and cytokines were evaluated using mixed-models.

RESULT

IL-6, IL-8, IL-10, and IL-13 levels were inversely related to selected HRV metrics.

CONCLUSION

Inflammation-modulating cytokines may be important mediators in the autonomic dysfunction observed in newborns with HIE.

Effect of mild hypothermia preconditioning against low temperature (4°C) induced rat liver cell injury in vitro

Bioartificial liver holds special position in the field of regenerative medicine, and cold environment at 4℃ is widely used for the short storage of both organ and liver cell for later application. However, the disadvantages of such cold storage could influence cell viability and lead to cell apoptosis in different degrees. In this study, we mainly explore the pre-protective effect of mild hypothermia against low temperature (4℃)-induced rat liver cell injury in vitro. Our results indicated that the precondition with mild hypothermia could increase cell viability, such as cell proliferation, LDH regulation and glycogen synthesis ability of liver cell. The precondition also decreased the ROS production and relieved cell apoptosis in liver cells. Compared with the model group, the mitochondrial membrane potential was restored in the mild hypothermia group, as well as the mitochondrial membrane permeability transition pore opening, indicating that the therapeutic mechanism was related to mitochondrial protection. Further analysis showed that PI3K-Akt-GSK3β signal pathway might be associated with the pre-protective effect of mild hypothermia. Thus, our study suggested that the precondition with mild hypothermia hold the protective effect for liver cell in cold environment, and further developed a novel strategy for the storage of liver seed cells, even bioartificial liver.

Brain-Eating Amoebae: Predilection Sites in the Brain and Disease Outcome

Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of granulomatous amoebic encephalitis (GAE), while Naegleria fowleri causes primary amoebic meningoencephalitis (PAM). PAM is an acute infection that lasts a few days, while GAE is a chronic to subacute infection that can last up to several months. Here, we present a literature review of 86 case reports from 1968 to 2016, in order to explore the affinity of these amoebae for particular sites of the brain, diagnostic modalities, treatment options, and disease outcomes in a comparative manner.

Neuroprotective hypothermia - Why keep your head cool during ischemia and reperfusion

BACKGROUND

Targeted temperature management (TTM) is the induced cooling of the entire body or specific organs to help prevent ischemia and reperfusion (I/R) injury, as may occur during major surgery, cardiac resuscitation, traumatic brain injury and stroke. Ischemia and reperfusion induce neuronal damage by mitochondrial dysfunction and oxidative injury, ER stress, neuronal excitotoxicity, and a neuroinflammatory response, which may lead to activation of apoptosis pathways.

SCOPE OF REVIEW

The aim of the current review is to discuss TTM targets that convey neuroprotection and to identify potential novel pharmacological intervention strategies for the prevention of cerebral ischemia and reperfusion injury.

MAJOR CONCLUSIONS

TTM precludes I/R injury by reducing glutamate release and oxidative stress and inhibiting release of pro-inflammatory factors and thereby counteracts mitochondrial induced apoptosis, neuronal excitotoxicity, and neuroinflammation. Moreover, TTM promotes regulation of the unfolded protein response and induces SUMOylation and the production of cold shock proteins. These advantageous effects of TTM seem to depend on the clinical setting, as well as type and extent of the injury. Therefore, future aims should be to refine hypothermia management in order to optimize TTM utilization and to search for pharmacological agents mimicking the cellular effects of TTM.

GENERAL SIGNIFICANCE

Bundling knowledge about TTM in the experimental, translational and clinical setting may result in better approaches for diminishing I/R damage. While application of TTM in the clinical setting has some disadvantages, targeting its putative protective pathways may be useful to prevent I/R injury and reduce neurological complications.

Long-Term Effects of Induced Hypothermia on Local and Systemic Inflammation - Results from a Porcine Long-Term Trauma Model

Background

Hypothermia has been discussed as playing a role in improving the early phase of systemic inflammation. However, information on the impact of hypothermia on the local inflammatory response is sparse. We therefore investigated the kinetics of local and systemic inflammation in the late posttraumatic phase after induction of hypothermia in an established porcine long-term model of combined trauma.

Materials & Methods

Male pigs (35 ± 5kg) were mechanically ventilated and monitored over the study period of 48 h. Combined trauma included tibia fracture, lung contusion, liver laceration and pressure-controlled hemorrhagic shock (MAP < 30 ± 5 mmHg for 90 min). After resuscitation, hypothermia (33°C) was induced for a period of 12 h (HT-T group) with subsequent re-warming over a period of 10 h. The NT-T group was kept normothermic. Systemic and local (fracture hematoma) cytokine levels (IL-6, -8, -10) and alarmins (HMGB1, HSP70) were measured via ELISA.

Results

Severe signs of shock as well as systemic and local increases of pro-inflammatory mediators were observed in both trauma groups. In general the local increase of pro- and anti-inflammatory mediator levels was significantly higher and prolonged compared to systemic concentrations. Induction of hypothermia resulted in a significantly prolonged elevation of both systemic and local HMGB1 levels at 48 h compared to the NT-T group. Correspondingly, local IL-6 levels demonstrated a significantly prolonged increase in the HT-T group at 48 h.

Conclusion

A prolonged inflammatory response might reduce the well-described protective effects on organ and immune function observed in the early phase after hypothermia induction. Furthermore, local immune response also seems to be affected. Future studies should aim to investigate the use of therapeutic hypothermia at different degrees and duration of application.

Association of brain injury and neonatal cytokine response during therapeutic hypothermia in newborns with hypoxic-ischemic encephalopathy

BACKGROUND

Cytokines have been proposed as mediators of neonatal brain injury via neuroinflammatory pathways triggered by hypoxia-ischemia. Limited data are available on cytokine profiles in larger cohorts of newborns with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH).

METHODS

Serum cytokines interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, tumor necrosis factor-α, and interferon-γ were measured in newborns with HIE at 24 and 72 h of TH. Differences between infants with favorable (survivors with mild/no magnetic resonance imaging (MRI) injury) vs. adverse outcome (death or moderate/severe MRI injury) were compared using mixed models to adjust for covariates.

RESULTS

Data from 36 term newborns with HIE (favorable outcome: n = 20, adverse outcome: n = 16) were evaluated. Cytokines IL-1β, IL-2, IL-6, IL-8, IL-10, and IL-13 were elevated in the adverse relative to favorable outcome group at 24 h. IL-6 remained significantly elevated in the adverse outcome group at 72 h. IL-6 and IL-10 remained significantly associated with outcome group after controlling for covariates.

CONCLUSION

Inflammatory cytokines are elevated in HIE newborns with brain injury by MRI. In particular, IL-6 and IL-10 were associated with adverse outcomes after controlling for baseline characteristics and severity of presentation. These data suggest that cytokine response may identify infants in need of additional neuroprotective interventions.

Glibenclamide enhances the effects of delayed hypothermia after experimental stroke in rats

In order to evaluate whether glibenclamide can extend the therapeutic window during which induced hypothermia can protect against stroke, we subjected adult male Sprague-Dawley rats to middle cerebral artery occlusion (MCAO). We first verified the protective effects of hypothermia induced at 0, 2, 4 or 6h after MCAO onset, and then we assessed the effects of the combination of glibenclamide and hypothermia at 6, 8 or 10h after MCAO onset. At 24h after MCAO, we assessed brain edema, infarct volume, modified neurological severity score, Evans Blue leakage and expression of Sulfonylurea receptor 1 (SUR1) protein and pro-inflammatory factors. No protective effects were observed when hypothermia was induced too long after MCAO. At 6h after MCAO onset, hypothermia alone failed to decrease cerebral edema and infarct volume, but the combination of glibenclamide and hypothermia decreased both. The combination also improved neurological outcome, ameliorated blood-brain barrier damage and decreased levels of COX-2, TNF-α and IL-1β. These results suggest that glibenclamide enhances and extends the therapeutic effects of delayed hypothermia against ischemia stroke, potentially by ameliorating blood-brain barrier damage and declining levels of pro-inflammatory factors.

Influence of hypothermia and subsequent rewarming upon leukocyte-endothelial interactions and expression of Junctional-Adhesion-Molecules A and B

Patients with risks of ischemic injury, e.g. during circulatory arrest in cardiac surgery, or after resuscitation are subjected to therapeutic hypothermia. For aortic surgery, the body is traditionally cooled down to 18 °C and then rewarmed to body temperature. The role of hypothermia and the subsequent rewarming process on leukocyte-endothelial interactions and expression of junctional-adhesion-molecules is not clarified yet. Thus, we investigated in an in-vitro model the influence of temperature modulation during activation and transendothelial migration of leukocytes through human endothelial cells. Additionally, we investigated the expression of JAMs in the rewarming phase. Exposure to low temperatures alone during transmigration scarcely affects leukocyte extravasation, whereas hypothermia during treatment and transendothelial migration improves leukocyte-endothelial interactions. Rewarming causes a significant up-regulation of transmigration with falling temperatures. JAM-A is significantly modulated during rewarming. Our data suggest that transendothelial migration of leukocytes is not only modulated by cell-activation itself. Activation temperatures and the rewarming process are essential. Continued hypothermia significantly inhibits transendothelial migration, whereas the rewarming process enhances transmigration strongly. The expression of JAMs, especially JAM-A, is strongly modulated during the rewarming process. Endothelial protection prior to warm reperfusion and mild hypothermic conditions reducing the difference between hypothermia and rewarming temperatures should be considered.

Adenosine 5'-monophosphate-induced hypothermia inhibits the activation of ERK1/2, JNK, p38 and NF-κB in endotoxemic rats

Many studies have shown that LPS mainly activates four signal transduction pathways to induce inflammation, namely the p38, ERK1/2, JNK and IKK/NF-κB pathways. Studies have demonstrated that 5'-AMP-induced hypothermia (AIH) exhibits high anti-inflammatory capabilities. In this study, we explore that how AIH inhibits the inflammatory response. Wistar rats were divided into five groups: a control group, an LPS group, a 5'-AMP pre-treatment group, a 5'-AMP post-treatment group and a 5'-AMP group. For each group, plasma and lung were collected from the rats at 6h and 12h after LPS injection. ELISA assays were used to detect plasma levels of CD14, CRP and MCP-1. Inflammatory pathway activation and TLR4 expression were assayed separately by Western blot analysis and immunohistochemistry. Our results showed that rats treated with AIH either before or after an LPS-challenge had a significant decrease in plasma levels of CD14, CRP and TLR4 compared with rats that received LPS only. Western blot analysis showed that AIH inhibited the activation of extracellular signal-regulated kinases (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) and NF-κB in inflammatory rats. Our study concluded that AIH attenuated LPS-induced inflammation mainly by inhibiting activation on the ERK1/2, p38, JNK and NF-κB signaling pathways.

Hypothermia induced by adenosine 5'-monophosphate attenuates injury in an L-arginine-induced acute pancreatitis rat model

BACKGROUND AND AIM

This study sought to investigate the effects of hypothermia induced by adenosine 5'-monophosphate (5'-AMP) on L-arginine (L-Arg)-induced acute pancreatitis in rats.

METHODS

The rats were divided into four groups: the control group, the acute pancreatitis group, the 5'-AMP pretreatment group, and the 5'-AMP posttreatment group. Rats in all groups, except for the control group, received two injections of 2.5 g/kg body weight (intraperitoneally) L-Arg, with an interval of 1 h between the injections. Subsequently, the rats were observed to assess whether hypothermia induced by 5'-AMP could effectively inhibit inflammation associated with L-Arg-induced acute pancreatitis in rats.

RESULTS

Hypothermia induced by 5'-AMP produced protective effects in our acute pancreatitis model. These effects exhibited the following manifestations: (i) a significant reduction in rat mortality rates; (ii) a significant decrease in the occurrence of pancreatic edema; (iii) significant reductions in serum amylase (P < 0.001), interleukin-6 (P < 0.001), interleukin-1β (P < 0.001) and tumor necrosis factor-α (P < 0.001); (iv) the significant inhibition of nuclear factor-κB (NF-κB) activation in rats that were pre- and posttreated with 5'-AMP compared with rats that were only injected with L-Arg; and (v) significant decreases in the occurrence of pancreatic interstitial edema, inflammatory cell infiltration, hemorrhage, and acinar cell necrosis.

CONCLUSIONS

Hypothermia induced by 5'-AMP could inhibit the acute inflammatory reaction and NF-κB activation associated with acute pancreatitis.

Hypothermia protects against fulminant hepatitis in mice by reducing reactive oxygen species production

OBJECTIVE

Mild hypothermia (32-33°C) shows protective effects in patients with brain damage and cardiac arrest. Although cold-inducible RNA-binding protein (CIRP) contributes to the protective effects of hypothermia through extracellular signal-regulated kinase activation in fibroblasts, the effects of hypothermia in the liver remain unclear.

METHODS

We analysed the effects of cold temperature on fulminant hepatitis, a potentially fatal disease, using the D-galactosamine (GalN)/lipopolysaccharide (LPS) and concanavalin (con) A-induced hepatitis models in mice. After GalN/LPS administration and anaesthesia, mice in the hypothermia group were kept at 25°C and those in control group were kept at 35°C. After concanavalin A (con A) administration, the mice in the hypothermia group were placed in a chamber with an ambient temperature of 6°C for 1.5 h.

RESULTS

Hypothermia attenuated liver injury and prolonged survival. Activation of c-Jun N-terminal kinase and Akt, which are involved in reactive oxygen species (ROS) accumulation, was suppressed by low temperature. Hypothermia significantly decreased oxidized protein levels, and treatment with N-acetyl-L-cysteine, an antioxidant, attenuated GalN/LPS-induced liver injury. In con A-induced hepatitis, CIRP expression was upregulated and Bid expression was downregulated, resulting in decreased apoptosis of hepatocytes in the hypothermia group.

CONCLUSIONS

These data suggest that hypothermia directly protects hepatocytes from cell death via reduction of ROS production in fulminant hepatitis.

Five-day whole-body cryostimulation, blood inflammatory markers, and performance in high-ranking professional tennis players

CONTEXT

Tournament season can provoke overreaching syndrome in professional tennis players, which may lead to deteriorated performance. Thus, appropriate recovery methods are crucial for athletes in order to sustain high-level performance and avoid injuries. We hypothesized that whole-body cryostimulation could be applied to support the recovery process.

OBJECTIVE

To assess the effects of 5 days of whole-body cryostimulation combined with moderate-intensity training on immunologic, hormonal, and hematologic responses; resting metabolic rate; and tennis performance in a posttournament season.

DESIGN

Controlled laboratory study.

SETTING

National Olympic Sport Centre.

PATIENTS OR OTHER PARTICIPANTS

Twelve high-ranking professional tennis players.

INTERVENTION(S)

Participants followed a moderate-intensity training program. A subgroup was treated with the 5-day whole-body cryostimulation (-120°C) applied twice a day. The control subgroup participated in the training only. Main Outcome Measure(s): Pretreatment and posttreatment blood samples were collected and analyzed for tumor necrosis factor α, interleukin 6, testosterone, cortisol, and creatine kinase. Resting metabolic rate and performance of a tennis drill were also assessed.

RESULTS

Proinflammatory cytokine (tumor necrosis factor α) decreased and pleiotropic cytokine (interleukin 6) and cortisol increased in the group exposed to cryostimulation. In the same group, greater stroke effectiveness during the tennis drill and faster recovery were observed. Neither the training program nor cryostimulation affected resting metabolic rate.

CONCLUSIONS

Professional tennis players experienced an intensified inflammatory response after the completed tournament season, which may lead to overreaching. Applying whole-body cryostimulation in conjunction with moderate-intensity training was more effective for the recovery process than the training itself. The 5-day exposure to cryostimulation twice a day ameliorated the cytokine profile, resulting in a decrease in tumor necrosis factor α and an increase in interleukin 6.

Hypothermia induced by adenosine 5'-monophosphate attenuates early stage injury in an acute gouty arthritis rat model

To investigate whether the hypothermia induced by Adenosine 5'-Monophosphate (5'-AMP) could attenuate early stage injury in a rat acute gouty arthritis model. Ankle joint injection with monosodium urate monohydrate crystals (MSU crystals) in hypothermia rat model which was induced by 5'-AMP and then observe whether hypothermia induced by 5'-AMP could be effectively inhibit the inflammation on acute gouty arthritis in rats. AMP-induced hypothermia has protective effects on our acute gouty arthritis, which was demonstrated by the following criteria: (1) a significant reduction in the ankle swelling (p < 0.001); (2) a significant decrease in the occurrence of leukocyte infiltration and mild hemorrhage; (3) a significant reduction in the presence of serum Interleukin-1β (IL-1β, p < 0.001) and metalloproteinase-9 (MMP-9, p < 0.001); and (4) a significant inhibition in the Nuclear Factor -κappaB (NF-κB) activity (p < 0.001). AMP-induced hypothermia could inhibit acute inflammation reaction and protect the synovial tissue against acute injury in a rat acute gouty arthritis model.

Year in review 2011: Critical Care--Neurocritical care

Contributions from the neurosciences to Critical Care in 2011 covered an array of topics. We learned about potential biomarkers for, and the effect of cerebral oxygen metabolism on, delirium, in addition to treatment of the latter. A group of investigators studied surface cooling in healthy awake volunteers, and incidence of infection associated with therapeutic hypothermia. The effects of statin and erythropoietin on stroke were revisited, and the role of adhesion molecule in the inflammatory reaction accompanying intracerebral hemorrhage was scrutinized. Biomarkers in subarachnoid hemorrhage and their relationship to vasospasm and outcome, and effect of daylight on outcome in this patient population, as well as a new meta-analysis of statin therapy were among the research in subarachnoid hemorrhage. Moreover, 2011 witnessed the publication of a multidisciplinary consensus conference's recommendations on the critical care management of subarachnoid hemorrhage. Results of studies regarding the diagnosis and vascular complications of meningitis were reported. Traumatic brain injury received its share of articles addressing therapy with hypertonic saline and surgical decompression, the development of coagulopathy, and biomarkers to help with prognostication. Finally, research on the treatment of Guillain-Barre syndrome in children, prediction of long-term need of ventilatory support, and pathophysiology of critical illness polyneuropathy and myopathy were reported.

Serum cytokines in a clinical trial of hypothermia for neonatal hypoxic-ischemic encephalopathy

Inflammatory cytokines may mediate hypoxic-ischemic (HI) injury and offer insights into the severity of injury and the timing of recovery. In our randomized, multicenter trial of hypothermia, we analyzed the temporal relationship of serum cytokine levels in neonates with hypoxic-ischemic encephalopathy (HIE) with neurodevelopmental outcome at 12 months. Serum cytokines were measured every 12 hours for 4 days in 28 hypothermic (H) and 22 normothermic (N) neonates with HIE. Monocyte chemotactic protein-1 (MCP-1) and interleukins (IL)-6, IL-8, and IL-10 were significantly higher in the H group. Elevated IL-6 and MCP-1 within 9 hours after birth and low macrophage inflammatory protein 1a (MIP-1a) at 60 to 70 hours of age were associated with death or severely abnormal neurodevelopment at 12 months of age. However, IL-6, IL-8, and MCP-1 showed a biphasic pattern in the H group, with early and delayed peaks. In H neonates with better outcomes, uniform down modulation of IL-6, IL-8, and IL-10 from their peak levels at 24 hours to their nadir at 36 hours was observed. Modulation of serum cytokines after HI injury may be another mechanism of improved outcomes in neonates treated with induced hypothermia.

Hypothermia induced by adenosine 5'-monophosphate attenuates acute lung injury induced by LPS in rats

We have built a rat's model to investigate whether the hypothermia induced by adenosine 5′-monophosphate (5′-AMP) (AIH) could attenuate acute lung injury induced by LPS in rats. We detected the inflammatory cytokine levels in the plasma and bronchoalveolar lavage fluid samples, and we analyzed the pathological changes in the lungs. We have found that AIH can effectively inhibit acute inflammatory reactions and protect the lung from acute injury induced by LPS in rats.

Molecular and cellular pathways as a target of therapeutic hypothermia: pharmacological aspect

Induced therapeutic hypothermia is the one of the most effective tools against brain injury and inflammation. Even though its beneficial effects are well known, there are a lot of pitfalls to overcome, since the potential adverse effects of systemic hypothermia are still troublesome. Without the knowledge of the precise mechanisms of hypothermia, it will be difficult to tackle the application of hypothermia in clinical fields. Better understanding of the characteristics and modes of hypothermic actions may further extend the usage of hypothermia by developing novel drugs based on the hypothermic mechanisms or by combining hypothermia with other therapeutic modalities such as neuroprotective drugs. In this review, we describe the potential therapeutic targets for the development of new drugs, with a focus on signal pathways, gene expression, and structural changes of cells. Theapeutic hypothermia has been shown to attenuate neuroinflammation by reducing the production of reactive oxygen species and proinflammatory mediators in the central nervous system. Along with the mechanism-based drug targets, applications of therapeutic hypothermia in combination with drug treatment will also be discussed in this review.

Role of induced hypothermia in thoracoabdominal aortic aneurysm surgery

For more than 50 years, hypothermia has been used in aortic surgery as a tool for neuroprotection. Hypothermia has been introduced into thoracoabdominal aortic aneurysm (TAAA) surgery by many cardiovascular centers to protect the body's organs, including the spinal cord. Numerous publications have shown that hypothermia can prevent immediate and delayed motor dysfunction after aortic cross-clamping. Here, we reviewed the historical application of hypothermia in aortic surgery, role of hypothermia in preclinical studies, cellular and molecular mechanisms by which hypothermia confers neuroprotection, and the role of systemic and regional hypothermia in clinical protocols to reduce and/or eliminate the devastating consequences of ischemic spinal cord injury after TAAA repair.

Implication for long-term hypothermia on degradation of interleukin-8 mRNA in endothelial cells stimulated with lipopolysaccharides

This experimental study investigated the effects of long-term hypothermia on the production of interleukin (IL)-8 protein and its mRNA expression in endothelial cells stimulated by lipopolysaccharides (LPS). Human umbilical vein endothelial cells were separated into a non-cooling group (N group: 37°C) and a cooling group (C group: 30°C). These groups were incubated with LPS (1 μg/mL) for 0, 2, 6, 24, 48, 72, and 96 hours. Production of the IL-8 protein secreted into the supernatant and mRNA expression in the cells were measured using enzyme-linked immunoabsorbent assay (ELISA) and real-time reverse transcription polymerase chain reaction (RT-PCR) analysis. To evaluate mRNA stability, both groups were incubated with actinomycin D at 6 hours after incubation with LPS for 24 hours. The degradation ratio was calculated by comparing the total expression of mRNA at 6 hours versus 0 hours. The protein levels in the C group were significantly lower than the N group between 6 and 96 hours. The mRNA expression in the C group was also significantly lower than in the N group up to 48 hours, but at 72 hours it was significantly higher than N group. IL-8 mRNA was less degraded in the C group compared to the N group. Under long-term hypothermia, IL-8 protein production was suppressed, while IL-8 mRNA was stabilized after LPS treatment. The potential of IL-8 to produce an inflammatory response in endothelial cells may persist even during long-term hypothermia.

Establishment of a coculture model for studying inflammation after pediatric cardiopulmonary bypass: from bench to bedside

Cardiopulmonary bypass (CPB) has been known to induce an inflammatory response that is influenced by various factors. Hypothermia is supposed to reduce inflammation after CPB. We developed an in vitro coculture model for CPB and compared the effects of hypothermia on the inflammatory response in the coculture model with results from a clinical prospective randomized trial. The coculture model consisted of endothelial cells and monocytes. Cells were stimulated with tumor necrosis factor (TNF)-α and exposed to deep hypothermia (20°C) or normothermia (37°C). In the clinical trial, 20 patients undergoing CPB for ventricular septum defect receive either normothermic (37°C) or mild hypothermic (32°C) CPB. We observed a significant interleukin (IL)-6 and IL-8 release in the coculture model 2 and 24 h after the experimental start. In the clinical trial, cytokines were significantly increased directly after weaning from CPB and remained elevated until 24 h. IL-8 and IL-6 secretions were similar in the hypothermic and normothermic group of the coculture model and the patients after 24 h. These results demonstrate that the inflammatory reaction observed in our coculture model is comparable with the cytokine increase in the blood of children undergoing CPB. Our coculture model could be useful for studies on the mechanisms of CPB-induced inflammation.

Facts and fiction: the impact of hypothermia on molecular mechanisms following major challenge

Numerous multiple trauma and surgical patients suffer from accidental hypothermia. While induced hypothermia is commonly used in elective cardiac surgery due to its protective effects, accidental hypothermia is associated with increased posttraumatic complications and even mortality in severely injured patients. This paper focuses on protective molecular mechanisms of hypothermia on apoptosis and the posttraumatic immune response. Although information regarding severe trauma is limited, there is evidence that induced hypothermia may have beneficial effects on the posttraumatic immune response as well as apoptosis in animal studies and certain clinical situations. However, more profound knowledge of mechanisms is necessary before randomized clinical trials in trauma patients can be initiated.

Hypothermia does not increase the risk of infection: a case control study

Introduction

Hypothermia may improve outcome in patients after traumatic brain injury, especially when hypothermia is maintained for more than 48 hours. In the acute phase, patients with severe brain injury are more vulnerable to infections. Prolonged hypothermic treatment may further enhance the risk of infection. Selective decontamination of the digestive tract (SDD) reduces the risk of respiratory tract infections. The aim of this study was to investigate the incidence of infections in patients treated with hypothermia and normothermia while receiving SDD.

Methods

In this retrospective case control study 35 patients treated with prolonged hypothermia (cases) were identified and 169 patients with severe brain injury were included (controls). Propensity score matching was performed to correct for differences in baseline characteristics and clinical parameters. Primary outcome was the incidence of infection. The secondary endpoints were the micro-organisms found in the surveillance cultures and infection. In addition, a number of clinical characteristics were assessed.

Results

The demographic and clinical data indicated that the cases and controls were well matched. The overall risk of infection during ICU stay was 20% in the hypothermia groups versus 34.4% in the normothermia group (P = 0.388). Pneumonia was diagnosed in 11.4% of patients in both groups (P = 1.000). The incidence of meningitis, wound infection, bacteremia, and urinary tract infection was low and comparable between the groups. SDD surveillance cultures indicated a higher colonization with gram-negative bacteria in the rectal samples of the hypothermia patients.

Conclusions

Hypothermia does not increase the risk of infection in patients treated with SDD.

Hypothermia-induced neurite outgrowth is mediated by tumor necrosis factor-alpha

Systemic or brain-selective hypothermia is a well-established method for neuroprotection after brain trauma. There is increasing evidence that hypothermia exerts beneficial effects on the brain and may also support regenerative responses after brain damage. Here, we have investigated whether hypothermia influences neurite outgrowth in vitro via modulation of the post-injury cytokine milieu. Organotypic brain slices were incubated: deep hypothermia (2 h at 17 degrees C), rewarming (2 h up to 37 degrees C), normothermia (20 h at 37 degrees C). Neurite density and cytokine release (IL 1beta, IL-6, IL-10, and TNF-alpha) were investigated after 24 h. For functional analysis mice deficient in NT-3/NT-4 and TNF-alpha as well as the TNF-alpha inhibitor etanercept were used. Hypothermia led to a significant increase of neurite outgrowth, which was independent of neurotrophin signaling. In contrast to other cytokines investigated, TNF-alpha secretion by organotypic brain slices was significantly increased after deep hypothermia. Moreover, hypothermia-induced neurite extension was abolished after administration of the TNF-alpha inhibitor and in TNF-alpha knockout mice. We demonstrate that TNF-alpha is responsible for inducing neurite outgrowth in the context of deep hypothermia and rewarming. These data suggest that hypothermia not only exerts protective effects in the CNS but may also support neurite outgrowth as a potential mechanism of regeneration.

Macrophage migration inhibitory factor increases leukocyte-endothelial interactions in human endothelial cells via promotion of expression of adhesion molecules

Macrophage migration inhibitory factor (MIF) has been shown to promote leukocyte-endothelial cell interactions, although whether this occurs via an effect on endothelial cell function remains unclear. Therefore, the aims of this study were to examine the ability of MIF expressed by endothelial cells to promote leukocyte adhesion and to investigate the effect of exogenous MIF on leukocyte-endothelial interactions. Using small interfering RNA to inhibit HUVEC MIF production, we found that MIF deficiency reduced the ability of TNF-stimulated HUVECs to support leukocyte rolling and adhesion under flow conditions. These reductions were associated with decreased expression of E-selectin, ICAM-1, VCAM-1, IL-8, and MCP-1. Inhibition of p38 MAPK had a similar effect on adhesion molecule expression, and p38 MAPK activation was reduced in MIF-deficient HUVECs, suggesting that MIF mediated these effects via promotion of p38 MAPK activation. In experiments examining the effect of exogenous MIF, application of MIF to resting HUVECs failed to induce leukocyte rolling and adhesion, whereas addition of MIF to TNF-treated HUVECs increased these interactions. This increase was independent of alterations in TNF-induced expression of E-selectin, VCAM-1, and ICAM-1. However, combined treatment with MIF and TNF induced de novo expression of P-selectin, which contributed to leukocyte rolling. In summary, these experiments reveal that endothelial cell-expressed MIF and exogenous MIF promote endothelial adhesive function via different pathways. Endogenous MIF promotes leukocyte recruitment via effects on endothelial expression of several adhesion molecules and chemokines, whereas exogenous MIF facilitates leukocyte recruitment induced by TNF by promoting endothelial P-selectin expression.

Specific p38 inhibition in stimulated endothelial cells: a possible new anti-inflammatory strategy after hypothermia and rewarming

To protect immature organ systems during corrective cardiac surgery, patients are cooled to a minimal temperature of 17 degrees C during cardiopulmonary bypass (CPB). However hypothermic CPB triggers the whole body inflammatory response and results in unwanted prolonged inflammation. The present study was designed to clarify the hypothermia and rewarming induced mechanisms and examine interventional pharmacological strategies that could prevent prolonged inflammation. Stimulated primary human umbilical vein endothelial cells (HUVECs) were exposed to a dynamic temperature protocol analogous to clinical settings. Furthermore endothelial cells were pretreated with methylprednisolone and/or tacrolimus as well as with MAPK inhibitors (SB203580, U0126 and SP600125). Cell viability, expression of IL-6 and ERK 1/2, p38 and SAPK/JNK were investigated. Stimulated endothelial cells secreted significantly higher IL-6 protein 2h after rewarming in comparison to normothermic control cells. Moreover, dynamic temperature changes lead to increased MAPK phosphorylation. Only the combined pre-treatment with MP and TAC served to inhibit the IL-6 secretion. As intracellular signalling pathway we could demonstrate that SB203580 as specific p38 inhibitor most effectively down regulated the unwanted IL-6 release after cooling and rewarming. Therefore inhibition of p38 or components of the p38 pathway could be a promising and selective antiinflammatory therapeutic target after hypothermic CPB.

Hypothermic organ preservation by static storage methods: Current status and a view to the future

The donor organ shortage is the largest problem in transplantation today and is one where organ preservation technology has an important role to play. Static storage of solid organs, especially of the kidney, continues to be the most common method employed for storage and transport of organs from deceased donors. However, the increase in organs obtained from expanded criteria donors and donors with cardiac death provide new challenges in crafting effective preservation methods for the future. This article reviews the current status of static hypothermic storage methods and discusses potential avenues for future exploitation of this technology as the available organ pool is expanded into the more marginal donor categories.