The association between serum adhesion molecules and outcome in acute spontaneous intracerebral hemorrhage

Introduction  

Serum concentrations of adhesion molecules may be connected to the pathogenesis of secondary brain injury after spontaneous intracerebral hemorrhage (ICH). This study posits the hypothesis that levels of adhesion molecules substantially increase after ICH and are decreased thereafter, and that they can predict treatment outcomes.     

Mild hypothermia alone or in combination with anesthetic post-conditioning reduces expression of inflammatory cytokines in the cerebral cortex of pigs after cardiopulmonary resuscitation

Introduction  

Hypothermia improves survival and neurological recovery after cardiac arrest. Pro-inflammatory cytokines have been implicated in focal cerebral ischemia/reperfusion injury. It is unknown whether cardiac arrest also triggers the release of cerebral inflammatory molecules, and whether therapeutic hypothermia alters this inflammatory response. This study sought to examine whether hypothermia or the combination of hypothermia with anesthetic post-conditioning with sevoflurane affect cerebral inflammatory response after cardiopulmonary resuscitation.     

Hyperoxemic reperfusion after prolonged cardiac arrest in a rat cardiopulmonary bypass resuscitation model

Background

The effect of hyperoxygenation at reperfusion, particularly in the setting of cardiac arrest, remains unclear. This issue was studied in a prolonged cardiac arrest model consisting of 25 min cardiac arrest in a rat resuscitated with cardiopulmonary bypass (CPB). The objective of this study was to determine the effect of hyperoxygenation following prolonged cardiac arrest resuscitation on mitochondrial and cardiac function.

Methods

Male Sprague-Dawley rats (400–450 g) were anesthetized with ketamine and xylazine and instrumented for closed chest cardiopulmonary bypass (CPB). Following a 25-min KCl-induced cardiac arrest, the animals were resuscitated by CPB with 100% oxygen. Three minutes after successful return of spontaneous circulation (ROSC), the animals received either normoxemic reperfusion (CPB with 40–50% oxygen) or hyperoxemic reperfusion (CPB with 100% oxygen) for 1 h. Post-resuscitation hemodynamics, cardiac function, mitochondrial function and immunostaining of 3-nitrotyrosine were compared between the two different treatment groups.

Results

At 1 h after ROSC, the hyperoxemic reperfusion group had a significant higher mean arterial pressure, less metabolic acidosis and better diastolic function than the normoxemic reperfusion group. Cardiac mitochondria from the hyperoxemic reperfusion group had a higher respiratory control ratio (RCR) and cardiac tissue showed less nitroxidative stress compared to the normoxemic reperfusion group.

Conclusions

One hour of hyperoxemic reperfusion after 25 min of cardiac arrest in an in vivo CPB model resulted in significant short-term improvement in myocardial and mitochondrial function compared with 1 h of normoxemic reperfusion. This myocardial response may differ from previously reported post-arrest hyperoxia mediated effects following shorter arrest times.     

Decreased soluble cell adhesion molecules after tirofiban infusion in patients with unstable angina pectoris

Aim  

The inflammatory response, initiated by neutrophil and monocyte adhesion to endothelial cells, is important in the pathogenesis of acute coronary syndromes. Platelets play an important role in inflammatory process by interacting with monocytes and neutrophils. In this study, we investigated the effect of tirofiban on the levels of cell adhesion molecules (soluble intercellular adhesion molecule-1, sICAM-1, and vascular cell adhesion molecule-1, sVCAM-1) in patients with unstable angina pectoris (AP).     

Cyclic arginine-glycine-aspartate attenuates acute lung injury in mice after intestinal ischemia/reperfusion

Introduction

Intestinal ischemia is a critical problem resulting in multiple organ failure and high mortality of 60 to 80%. Acute lung injury (ALI) is a common complication after intestinal ischemia/reperfusion (I/R) injuries and contributes to the high mortality rate. Moreover, activated neutrophil infiltration into the lungs is known to play a significant role in the progression of ALI. Integrin-mediated interaction is involved in neutrophil transmigration. Synthetic peptides containing an arginine-glycine-aspartate sequence compete with adhesive proteins and inhibit integrin-mediated interaction and signaling. Thus, we hypothesized that the administration of a cyclic arginine-glycine-aspartate peptide (cRGD) inhibited neutrophil infiltration and provided protection against ALI induced by intestinal I/R.

Methods

Ischemia in adult male C57BL/6 mice was induced by fastening the superior mesenteric artery with 4-0 suture. Forty-five minutes later, the vascular suture was released to allow reperfusion. cRGD (5 mg/kg body weight) or normal saline (vehicle) was administered by intraperitoneal injection 1 hour prior to ischemia. Blood, gut, and lung tissues were collected 4 hours after reperfusion for various measurements.

Results

Intestinal I/R caused severe widespread injury to the gut and lungs. Treatment with cRGD improved the integrity of microscopic structures in the gut and lungs, as judged by histological examination. Intestinal I/R induced the expression of β₁, β₂ and β₃ integrins, intercellular adhesion molecule-1, and fibronectin. cRGD significantly inhibited myeloperoxidase activity in the gut and lungs, as well as neutrophils and macrophages infiltrating the lungs. cRGD reduced the levels of TNF-α and IL-6 in serum, in addition to IL-6 and macrophage inflammatory protein-2 in the gut and lungs. Furthermore, the number of TUNEL-staining cells and levels of cleaved caspase-3 in the lungs were significantly lowered in the cRGD-treated mice in comparison with the vehicle mice.

Conclusions

Treatment with cRGD effectively protected ALI and gut injury, lowered neutrophil infiltration, suppressed inflammation, and inhibited lung apoptosis after intestinal I/R. Thus, there is potential for developing cRGD as a treatment for patients suffering from ALI caused by intestinal I/R.     

Olprinone attenuates the development of ischemia/reperfusion injury of the gut

Purpose  

Splanchnic artery occlusion (SAO) shock is a severe form of circulatory shock produced by ischemia and reperfusion of the splanchnic organs. The occlusion and reperfusion of the splanchnic arteries causes activation and adhesion of polymorphonuclear neutrophils (PMNs), release of proinflammatory substances and the formation of both species of oxygen and nitrogen derivatives free radicals. Olprinone is a specific phosphodiesterase-III inhibitor that has many properties; one of which is anti-inflammatory actions at therapeutic concentrations clinically used for heart failure. In this study, we wanted to evaluate the pharmacological action of olprinone (a PDEIII inhibitor) on SAO shock in mice.     

Prognostic value of minimal blood flow restoration in patients with acute myocardial infarction after reperfusion therapy

Purpose  

The prognostic impact of low-flow reperfusion after percutaneous coronary intervention (PCI) in patients with ST-segment elevation acute myocardial infarction (STEMI) is unknown. The aim of the study was to investigate the impact of low-flow reperfusion after PCI in patients with STEMI.     

Mild hypothermia in improving multiple organ dysfunction after cardiac arrest

BACKGROUND:

Resuscitation after cardiac arrest (CA) with a whole-body ischemia–reperfusion injury causes brain injury and multiple organ dysfunction (MODS). This study aimed to determine whether mild systemic hypothermia could decrease multiple organ dysfunctions after resuscitation from cardiac arrest.

METHODS:

The patients who had been resuscitated after cardiac arrest were reviewed. During the resuscitation they had been assigned to undergo therapeutic hypothermia (target temperature, 32°C to 34°C, measured in the rectum) over a period of 24 to 36 hours or to receive standard treatment with normothermia. Markers of different organ injury were evaluated for the first 72 hours after recovery of spontaneous circulation (ROSC).

RESULTS:

At 72 hours after ROSC, 23 patients in the hypothermia group for whom data were available had favorable neurologic, myocardial, hepatic and pulmonic outcomes as compared with 26 patients in the normothermia group. The values of renal function were not significantly different between the two groups. However, blood coagulation function was badly injured in the hypothermia group.

CONCLUSION:

In the patients who have been successfully resuscitated after cardiac arrest, therapeutic mild hypothermia can alleviate dysfunction after resuscitation from cardiac arrest.KEY WORDS: Cardiac arrest, Ischemia reperfusion injury, Mild hypothermia, Multiple organ dysfunction     

N-Acetyl-l-Cysteine Attenuates Ischemia/Reperfusion Injury–Induced Allodynia and N-Methyl-d-Aspartate Receptor Activation in Rats

Background

Although reactive oxygen species (ROS) are believed to be involved in pathogenic mechanisms that underlie complex regional pain syndrome type I (CRPS-I), the role of ROS in the central mechanism of CRPS is not fully understood.

Objective

In this study we investigated whether ROS scavenger N-acetyl-l-cysteine (NAC) was capable of attenuating mechanical allodynia and whether pain was decreased through modulating N-methyl-d-aspartate (NMDA) receptor activation in a chronic postischemia pain (CPIP) animal model that mimics the symptoms of CRPS-I.

Methods

Thirty male Sprague-Dawley rats were randomly allocated to 5 different groups: (1) sham rats and CPIP rats treated with (2) vehicle; (3) NAC 30 mg/kg; (4) NAC 100 mg/kg; and (5) NAC 300 mg/kg intraperitoneally at 15 minutes before reperfusion. CPIP was generated after a 3-hour ischemia/reperfusion injury on the hind limb using a tight fitting O-ring. Then, mechanical paw-withdrawal thresholds to von Frey stimuli were assessed before ischemia (baseline), at 4 hours; 1, 3, and 5 days; and 1, 2, 3, and 4 weeks after reperfusion. Another set of 5 animal groups in the same categories was used to determine phosphorylated NMDA receptor 1 subunit (pNR1) immunoreactivity in the ipsilateral L4/6 spinal cord at 3 days after reperfusion.

Results

The sham group showed no significant difference in pain thresholds over 4 weeks. With NAC treatment, the pain thresholds measured after reperfusion increased significantly, and this increase lasted 4 weeks after reperfusion compared with the vehicle group (P < 0.01 on the ipsilateral side and P < 0.05 on the contralateral side). The relative density of pNR1 at 3 days after reperfusion in NAC-treated rats decreased significantly compared with that of the vehicle group (all, P < 0.001). The NAC dose was significantly correlated not only with paw-withdrawal threshold (ρ = 0.979; P < 0.001) but also with the relative density of pNR1 (ρ = –0.875; P < 0.001).

Conclusions

NAC, administered during the pre-reperfusion period, had a long-term antiallodynic effect through the attenuation of NMDA receptor phosphorylation, leading to central sensitization.     

Regional myocardial function after intracoronary bone marrow cell injection in reperfused anterior wall infarction - a cardiovascular magnetic resonance tagging study

Background

Nuclear magnetic resonance (NMR) imaging and spectroscopy have been applied to assess skeletal muscle oxidative metabolism. Therefore, in-vivo NMR may enable the characterization of ischemia-reperfusion injury. The goal of this study was to evaluate whether NMR could detect the effects of ischemic preconditioning (IPC) in healthy subjects.

Methods

Twenty-three participants were included in two randomized crossover protocols in which the effects of IPC were measured by NMR and muscle force assessments. Leg ischemia was administered for 20 minutes with or without a subsequent impaired reperfusion for 5 minutes (stenosis model). IPC was administered 4 or 48 hours prior to ischemia. Changes in ³¹phosphate NMR spectroscopy and blood oxygen level-dependent (BOLD) signals were recorded. 3-Tesla NMR data were compared to those obtained for isometric muscular strength.

Results

The phosphocreatine (PCr) signal decreased robustly during ischemia and recovered rapidly during reperfusion. In contrast to PCr, the recovery of muscular strength was slow. During post-ischemic stenosis, PCr increased only slightly. The BOLD signal intensity decreased during ischemia, ischemic exercise and post-ischemic stenosis but increased during hyperemic reperfusion. IPC 4 hours prior to ischemia significantly increased the maximal PCr reperfusion signal and mitigated the peak BOLD signal during reperfusion.

Conclusions

Ischemic preconditioning positively influenced muscle metabolism during reperfusion; this resulted in an increase in PCr production and higher oxygen consumption, thereby mitigating the peak BOLD signal. In addition, an impairment of energy replenishment during the low-flow reperfusion was detected in this model. Thus, functional NMR is capable of characterizing changes in reperfusion and in therapeutic interventions in vivo.

Trial Registration

ClinicalTrials.gov: NCT00883467     

Circulating adhesion molecules in the critically ill: A comparison between trauma and sepsis patients

Objective  

The time course of circulating adhesion molecules was monitored in traumatized and sepsis patients.     

Changes in the sublingual microcirculation and endothelial adhesion molecules during the course of severe meningococcal disease treated in the paediatric intensive care unit

Purpose

The sublingual microcirculation can be visualised in real time using sidestream dark-field (SDF) imaging. Endothelial activation mediated through adhesion molecules may alter flow patterns in the microcirculation. We studied sublingual microcirculatory disturbances in children with meningococcal disease (MCD) and simultaneously measured plasma levels of adhesion molecules.

Method

Twenty children admitted to the paediatric intensive care unit (PICU) with MCD were studied. Forty healthy children were controls. The sublingual microcirculation was assessed at admission and at timed intervals until extubation. The microvascular flow index (MFI), capillary density (CD), proportion of perfused vessels (PPV) and perfused vessel density (PVD) were measured using SDF imaging. Plasma intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin and P-selectin were measured at admission and at timed intervals during the course of PICU treatment.

Results

Significant reductions in MFI, CD, PPV and PVD were found in children with MCD compared with controls (p?p?Conclusions Microcirculatory dysfunction is present in children with severe MCD with improvement alongside clinical recovery. Microcirculatory dysfunction correlated with markers of endothelial activation. Sublingual SDF imaging is feasible in children ventilated on PICU for severe sepsis and may prove useful in studies assessing illness severity and therapy.     

Heme arginate improves reperfusion patterns after ischemia: a randomized, placebo-controlled trial in healthy male subjects

Background

Heme arginate can induce heme oxygenase-1 to protect tissue against ischemia-reperfusion injury. Blood oxygen level dependent (BOLD) functional magnetic resonance imaging measures changes in tissue oxygenation with a high spatial and temporal resolution. BOLD imaging was applied to test the effect of heme arginate on experimental ischemia reperfusion injury in the calf muscles.

Methods

A two period, controlled, observer blinded, crossover trial was performed in 12 healthy male subjects. Heme arginate (1 mg/kg body weight) or placebo were infused 24 h prior to a 20 min leg ischemia induced by a thigh cuff. 3 Tesla BOLD-imaging of the calf was performed and signal time courses from soleus, gastrocnemius and tibialis anterior muscle were available from 11 participants for technical reasons.

Results

Peak reactive hyperemia signal of the musculature was significantly increased and occurred earlier after heme arginate compared to placebo (106.2±0.6% at 175±16s vs. 104.5±0.6% at 221±19s; p = 0.025 for peak reperfusion and p = 0.012 for time to peak).

Conclusions

A single high dose of heme arginate improves reperfusion patterns during ischemia reperfusion injury in humans. BOLD sensitive, functional MRI is applicable for the assessment of experimental ischemia reperfusion injury in skeletal muscle.

Trial registration

ClinicalTrials: {"type":"clinical-trial","attrs":{"text":"NCT01461512","term_id":"NCT01461512"}}NCT01461512EudraCT: 2008-006967-35     

Post-conditioning with gradually increased reperfusion provides better cardioprotection in rats

BACKGROUND:

Rapid and complete reperfusion has been widely adopted in the treatment of patients with acute myocardial infarction (AMI), but this process sometimes can cause severe reperfusion injury. This study aimed to investigate different patterns of post-conditioning in acute myocardial ischemia-reperfusion injury, and to detect the role of mitogen activated protein kinase (MAPK) during the injury.

METHODS:

Rats were randomly divided into five groups: sham group, reperfusion injury (R/ I) group, gradually decreased reperfusion group (GDR group, 30/10-25/15-15/25-10/30 seconds of reperfusion/ischemia), equal reperfusion group (ER group, 20/20 seconds reperfusion/ischemia, 4 cycles), and gradually increased reperfusion group (GIR group, 10/30-15/25-25/15-30/10 seconds of reperfusion/ischemia). Acute myocardial infarction and ischemic post-conditioning models were established in the rats. Six hours after reperfusion, 3 rats from each group were sacrificed and myocardial tissues were taken to measure the expressions of phosphorylation of extracellular signal-regulated protein kinase (P-ERK), phosphorylated c-Jun N-terminal kinase (P-JNK), mitogen-activated protein kinase p38 (p38 MAPK), tumor necrosis factor-α (TNF-α), caspases-8 in the myocardial tissue, and cytochrome c in the cytosol using Western blot. Hemodynamics was measured at 24 hours after reperfusion, the blood was drawn for the determination of cardiac enzymes, and the heart tissue was collected for the measurement of apoptosis using TUNEL. One-way analysis of variance and the Q test were employed to determine differences in individual variables between the 5 groups.

RESULTS:

Three post-conditioning patterns were found to provide cardioprotection (P<0.05) compared with R/I without postconditioning. GIR provided the best cardioprotection effect, followed by ER and then GDR. Apoptotic index and serum marker levels were reduced more significantly in GIR than in ER (P<0.05). The enhanced cardioprotection provided by GIR was accompanied with significantly increased levels of P-ERK 1/2 (1.82±0.22 vs. 1.54±0.32, P<0.05), and lower levels of p-JNK, p38 MAPK, TNF-α, caspase-8, caspase-9 and cytochrome in the cytoplasm (P<0.05), compared with ER. The infarct size was smaller in the GIR group than in the ER group, but this difference was not significant (16.30%±5.22% vs. 20.57%±6.32%, P<0.05). All the measured variables were improved more significantly in the GIR group than in the GDR group (P<0.05).

CONCLUSION:

Gradually increased reperfusion in post-conditioning could attenuate reperfusion injury more significantly than routine method, thereby the MAPK pathway plays an important role in this process.KEY WORDS: Ischemia-reperfusion injury, Postconditioning, Apoptosis     

Increased plasma methylglyoxal level, inflammation, and vascular endothelial dysfunction in diabetic nephropathy

Objectives

To investigate the association of plasma levels of methylglyoxal (MG) and markers of inflammation/endothelial dysfunction with diabetic nephropathy (DN).

Design and methods

Plasma levels of MG, cytokines, and adhesion molecules were measured in type 2 diabetic patients (T2DM), T2DM patients with DN, and the controls.

Results

Plasma MG levels in DN were significantly higher than those in T2DM and the controls (312 ± 135 vs. 212 ± 73 and 312 ± 135 vs. 147 ± 78 nmol/L, respectively, P < 0.001). The plasma levels of MG were positively correlated with the fasting glucose, HbA1c, and urinary albumin/creatinine ratio (r = 0.754, P < 0.05). Plasma levels of IL-6, TNF-α, and adhesion molecules were markedly increased in DN compared to T2DM patients and the controls.

Conclusions

Increased plasma levels of MG, cytokines, and adhesion molecules are associated with DN. These markers may be useful in predicting the development of DN.     

Akt or phosphoinositide-3-kinase inhibition reverses cardio-protection in Toll-like receptor 2 deficient mice

Aim

Absence or inhibition of Toll-like receptor 2 (TLR2) signalling during murine myocardial ischaemia/reperfusion (MI/R) decreases myocardial necrosis and inflammation, thereby ameliorating cardiac dysfunction and improving survival. In the present study, we provide evidence for the involvement of the phosphoinositide-3-kinase/Akt pathway in TLR2-dependent reperfusion injury.

Methods

Adult male wild-type (WT) and TLR2^−/− mice were subjected to myocardial ischaemia (30 min) and reperfusion (4 h). Animals were treated with phosphoinositide-3-kinase inhibitor wortmannin, Akt inhibitor V (triciribine), or vehicle 1 h prior to MI/R. Protein expression levels of Akt1 and phosphoinositide-3-kinase and their respective phosphorylated forms were determined by Western blot analysis. Myocardial necrosis was quantified after staining with the tetrazolium method and by troponin T plasma levels.

Results

TLR2^−/− mice displayed significantly increased Akt and phospho-Akt levels compared to WT mice, whilst no significant difference in phosphoinositide-3-kinase expression and phosphorylation could be observed. TLR2^−/− mice also showed a blunted myocardial necrosis, the extent of which inversely correlated with Akt expression and degree of phosphorylation. Pharmacological inhibition of both, phosphoinositide-3-kinase or Akt, reversed the cardioprotection observed in TLR2^−/− mice, whilst no effect could be observed in WT mice.

Conclusion

Akt is an important mediator of cardioprotection in TLR2^−/− animals during MI/R. The effect is, however, likely mediated by its genomic overexpression in the heart of TLR2^−/− animals whilst Akt activation by phosphoinositide-3-kinase is unaltered.     

Compared effects of inhibition and exogenous administration of hydrogen sulphide in ischaemia-reperfusion injury

Introduction

Haemorrhagic shock is associated with an inflammatory response consecutive to ischaemia-reperfusion (I/R) that leads to cardiovascular failure and organ injury. The role of and the timing of administration of hydrogen sulphide (H₂S) remain uncertain. Vascular effects of H₂S are mainly mediated through K⁺_ATP-channel activation. Herein, we compared the effects of D,L-propargylglycine (PAG), an inhibitor of H₂S production, as well as sodium hydrosulphide (NaHS), an H₂S donor, on haemodynamics, vascular reactivity and cellular pathways in a rat model of I/R. We also compared the haemodynamic effects of NaHS administered before and 10 minutes after reperfusion.

Methods

Mechanically ventilated and instrumented rats were bled during 60 minutes in order to maintain mean arterial pressure at 40 ± 2 mmHg. Ten minutes prior to retransfusion, rats randomly received either an intravenous bolus of NaHS (0.2 mg/kg) or vehicle (0.9% NaCl) or PAG (50 mg/kg). PNU, a pore-forming receptor inhibitor of K⁺_ATP channels, was used to assess the role of K⁺_ATP channels.

Results

Shock and I/R induced a decrease in mean arterial pressure, lactic acidosis and ex vivo vascular hyporeactivity, which were attenuated by NaHS administered before reperfusion and PNU but not by PAG and NaHS administered 10 minutes after reperfusion. NaHS also prevented aortic inducible nitric oxide synthase expression and nitric oxide production while increasing Akt and endothelial nitric oxide synthase phosphorylation. NaHS reduced JNK activity and p-P38/P38 activation, suggesting a decrease in endothelial cell activation without variation in ERK phosphorylation. PNU + NaHS increased mean arterial pressure when compared with NaHS or PNU alone, suggesting a dual effect of NaHS on vascular reactivity.

Conclusion

NaHS when given before reperfusion protects against the effects of haemorrhage-induced I/R by acting primarily through a decrease in both proinflammatory cytokines and inducible nitric oxide synthase expression and an upregulation of the Akt/endothelial nitric oxide synthase pathway.Keywords: hydrogen sulphide, inflammation mediators, therapeutic use, shock, hemorrhagic/drug therapy, haemodynamics/drug effects     

Upregulated expression of S100A8 in mice brain after focal cerebral ischemia reperfusion

BACKGROUND:

Recent studies have showed that S100A8 has been implicated in the pathobiology of inflammatory disorders, and that cerebral ischemia reperfusion (I/R) rapidly activates inflammation responses via Toll-like receptor 4 (TLR4). This study aimed to explore the expression of S100A8 and the relationship between S100A8 and TLR4 in focal cerebral ischemia reperfusion injury.

METHODS:

C3H/HeJ mice (n=30) and C3H/HeN mice (n=30) were divided randomly into a C3H/HeJ model group (n=18), a C3H/HeJ control group (n=12), a C3H/HeN model group (n=18), and a C3H/HeN control group (n=12). Middle cerebral artery I/R model in mice was produced using a thread embolism method. The brains of the mice were collected after ischemia for 1 hour and reperfusion for 12 hours. Stroke outcome was evaluated by determination of infarct volume and assessment of neurological impairment scores. Brain injury after cerebral I/R was observed by an optical microscope after TTC and HE dyeing. The immunofluorescence technique and real time PCR were used to test the expression level of S100A8 in brain damage.

RESULTS:

Compared with C3H/HeN mice, TLR4-deficient mice (C3H/HeJ) had lower infarct volumes and better outcomes in neurological tests. The levels of S100A8 increased sharply in the brains of mice after I/R injury. In addition, mice that lacked TLR4 (C3H/HeJ) had lower expression of I/R-induced S100A8 than C3H/HeN mice in the model group, indicating that a close relationship might exist between the levels of S100A8 and TLR4.

CONCLUSION:

S100A8 interaction with TLR4 might be involved in brain damage and in inflammation triggered by I/R injury.KEY WORDS: S100A8, Toll-like receptor 4, Cerebral ischemia reperfusion, Inflammation     

Early coronary revascularization improves 24 h survival and neurological function after ischemic cardiac arrest. A randomized animal study

Background

Survival after out-of-hospital cardiac arrest (OHCA) remains poor. Acute coronary obstruction is a major cause of OHCA. We hypothesize that early coronary reperfusion will improve 24 h-survival and neurological outcomes.

Methods

Total occlusion of the mid LAD was induced by balloon inflation in 27 pigs. After 5 min, VF was induced and left untreated for 8 min. If return of spontaneous circulation (ROSC) was achieved within 15 min (21/27 animals) of cardiopulmonary resuscitation (CPR), animals were randomized to a total of either 45 min (group A) or 4 h (group B) of LAD occlusion. Animals without ROSC after 15 min of CPR were classified as refractory VF (group C). In those pigs, CPR was continued up to 45 min of total LAD occlusion at which point reperfusion was achieved. CPR was continued until ROSC or another 10 min of CPR had been performed. Primary endpoints for groups A and B were 24-h survival and cerebral performance category (CPC). Primary endpoint for group C was ROSC before or after reperfusion.

Results

Early compared to late reperfusion improved survival (10/11 versus 4/10, p = 0.02), mean CPC (1.4 ± 0.7 versus 2.5 ± 0.6, p = 0.017), LVEF (43 ± 13 versus 32 ± 9%, p = 0.01), troponin I (37 ± 28 versus 99 ± 12, p = 0.005) and CK-MB (11 ± 4 versus 20.1 ± 5, p = 0.031) at 24-h after ROSC. ROSC was achieved in 4/6 animals only after reperfusion in group C.

Conclusions

Early reperfusion after ischemic cardiac arrest improved 24 h survival rate and neurological function. In animals with refractory VF, reperfusion was necessary to achieve ROSC.     

T cell–derived interleukin (IL)-21 promotes brain injury following stroke in mice

T lymphocytes are key contributors to the acute phase of cerebral ischemia reperfusion injury, but the relevant T cell–derived mediators of tissue injury remain unknown. Using a mouse model of transient focal brain ischemia, we report that IL-21 is highly up-regulated in the injured mouse brain after cerebral ischemia. IL-21–deficient mice have smaller infarcts, improved neurological function, and reduced lymphocyte accumulation in the brain within 24 h of reperfusion. Intracellular cytokine staining and adoptive transfer experiments revealed that brain-infiltrating CD4⁺ T cells are the predominant IL-21 source. Mice treated with decoy IL-21 receptor Fc fusion protein are protected from reperfusion injury. In postmortem human brain tissue, IL-21 localized to perivascular CD4⁺ T cells in the area surrounding acute stroke lesions, suggesting that IL-21–mediated brain injury may be relevant to human stroke.Stroke is one of the leading causes of death and disability worldwide. Clinical and preclinical experimental studies highlight the importance of inflammation in both acute and delayed neuronal tissue damage after ischemic stroke; however, the mechanisms and cells involved in this neuroinflammation are not fully understood. There is currently no available treatment targeting the acute immune response that develops in the brain after transient focal ischemia. Therefore, we sought to identify novel T cell–derived cytokines that contribute to acute cerebral reperfusion using the mouse model of transient middle cerebral artery occlusion (tMCAO).During the reperfusion of infarcted brain tissue, leukocytes accumulate in the injured brain where, in addition to clearing cell debris, they promote secondary tissue injury (Yilmaz and Granger, 2010). Within the acute phase of ischemic reperfusion (I/R) injury there are multiple waves of cell infiltration of macrophages, neutrophils, and lymphocytes (Gelderblom et al., 2009). Brain-infiltrating T cells have also been widely reported in stroke and animal models of stroke and are thought to have acute detrimental and delayed protective effects (Magnus et al., 2012). Conventionally, the protective role of T cells has been attributed to the accumulation of regulatory T cells within the CNS in later stages of reperfusion injury. These T cells produce a variety of cytokines including TGFβ and IL-10, which are both antiinflammatory and neuroprotective. (Liesz et al., 2009; Stubbe et al., 2013). In addition to having an established role in delayed neuroprotection, Kleinschnitz et al. (2013) have recently shown that CD4⁺ CD25⁺ regulatory T cells also promote acute ischemic injury through interaction with the cerebral vasculature. The acute detrimental effects can be further divided into early (24 h) and late (72 h) phases, with IL-17 production by nonconventional γδ T cells (less common T cell subset associated with mucosal tissues) possibly accounting for the latter by promoting neutrophil accumulation (Gelderblom et al., 2012).The mechanisms of the early detrimental effects of T cells after cerebral ischemia are least understood. Several laboratories have reported reduced neurological deficit and infarct volumes at 24–48 h reperfusion in T cell–deficient mice after tMCAO (Yilmaz and Granger, 2010). After tMCAO, recombination activating gene 1–deficient (RAG1 KO) mice, which lack T and B lymphocytes, have significantly smaller brain injury compared with controls; whereas, adoptive transfer of WT CD4⁺ helper T cells or CD8⁺ cytotoxic T cells increases stroke infarct volumes within 24 h after ischemia in these mice (Kleinschnitz et al., 2010). Additionally, TCR-transgenic mice and mice lacking co-stimulatory TCR signaling molecules were fully susceptible to acute I/R injury, indicating that T cell involvement at early time points is antigen-independent (Kleinschnitz et al., 2010). These data demonstrate that conventional CD4⁺ or CD8⁺ αβ T cells exacerbate acute injury after cerebral ischemia independently of TCR ligation, and this effect seems to be concomitant with an early increase in T cell infiltration into the postischemic brain, which many have reported to be between 3 and 48 h (Yilmaz et al., 2006; Gelderblom et al., 2009).Recent findings suggest that, in the postischemic brain, within hours of reperfusion T cells accumulate in postcapillary segments of periinfarct inflamed cerebral microvasculature characterized by high endothelial expression of chemokines and adhesion molecules. These postcapillary venules have been postulated to allow accumulating immune cells to activate each other and promote platelet adhesion in a process termed thrombo-inflammation (Nieswandt et al., 2011). Much research has been devoted to identifying T cell factors that promote thrombo-inflammation (Barone et al., 1997; Hedtjärn et al., 2002; Yilmaz et al., 2006; Shichita et al., 2009; Gelderblom et al., 2012); however, to our knowledge no study has yet identified the T cell–derived factors responsible for the early increase in infarct volumes at 24 h reperfusion. Here, we present data that identify IL-21 as a key CD4⁺ T cell–derived inflammatory factor that contributes to increased early ischemic tissue injury.