Increased Matrix Metalloproteinase-9 in Blood in Association with Activation of Interleukin-6 after Traumatic Brain Injury: Influence of Hypothermic Therapy

Use of hypothermia in the intensive care unit

Used for over 3600 years, hypothermia, or targeted temperature management (TTM), remains an ill defined medical therapy. Currently, the strongest evidence for TTM in adults are for out-of-hospital ventricular tachycardia/ventricular fibrillation cardiac arrest, intracerebral pressure control, and normothermia in the neurocritical care population. Even in these disease processes, a number of questions exist. Data on disease specific therapeutic markers, therapeutic depth and duration, and prognostication are limited. Despite ample experimental data, clinical evidence for stroke, refractory status epilepticus, hepatic encephalopathy, and intensive care unit is only at the safety and proof-of-concept stage. This review explores the deleterious nature of fever, the theoretical role of TTM in the critically ill, and summarizes the clinical evidence for TTM in adults.

MT5-MMP, ADAM-10, and N-cadherin act in concert to facilitate synapse reorganization after traumatic brain injury

Matrix metalloproteinases (MMPs) influence synaptic recovery following traumatic brain injury (TBI). Membrane type 5-matrix metalloproteinase (MT5-MMP) and a distintegrin and metalloproteinase-10 (ADAM-10) are membrane-bound MMPs that cleave N-cadherin, a protein critical to synapse stabilization. This study examined protein and mRNA expression of MT5-MMP, ADAM-10, and N-cadherin after TBI, contrasting adaptive and maladaptive synaptogenesis. The effect of MMP inhibition on MT5-MMP, ADAM-10, and N-cadherin was assessed during maladaptive plasticity and correlated with synaptic function. Rats were subjected to adaptive unilateral entorhinal cortical lesion (UEC) or maladaptive fluid percussion TBI+bilateral entorhinal cortical lesion (TBI+BEC). Hippocampal MT5-MMP and ADAM-10 protein was significantly elevated 2 and 7 days post-injury. At 15 days after UEC, each MMP returned to control level, while TBI+BEC ADAM-10 remained elevated. At 2 and 7 days, N-cadherin protein was below control. By the 15-day synapse stabilization phase, UEC N-cadherin rose above control, a shift not seen for TBI+BEC. At 7 days, increased TBI+BEC ADAM-10 transcript correlated with protein elevation. UEC ADAM-10 mRNA did not change, and no differences in MT5-MMP or N-cadherin mRNA were detected. Confocal imaging showed MT5-MMP, ADAM-10, and N-cadherin localization within reactive astrocytes. MMP inhibition attenuated ADAM-10 protein 15 days after TBI+BEC and increased N-cadherin. This inhibition partially restored long-term potentiation induction, but did not affect paired-pulse facilitation. Our results confirm time- and injury-dependent expression of MT5-MMP, ADAM-10, and N-cadherin during reactive synaptogenesis. Persistent ADAM-10 expression was correlated with attenuated N-cadherin level and reduced functional recovery. MMP inhibition shifted ADAM-10 and N-cadherin toward adaptive expression and improved synaptic function.

Therapeutic hypothermia for the management of intracranial hypertension in severe traumatic brain injury: a systematic review

BACKGROUND

Traumatic brain injury (TBI) is a major source of death and severe disability worldwide. Raised Intracranial pressure (ICP) is an important predictor of mortality in patients with severe TBI and aggressive treatment of elevated ICP has been shown to reduce mortality and improve outcome. The acute post-injury period in TBI is characterized by several pathophysiologic processes that start in the minutes to hours following injury. All of these processes are temperature-dependent; they are all aggravated by fever and inhibited by hypothermia.

METHODS

This study reviewed the current clinical evidence in support of the use of therapeutic hypothermia (TH) for the treatment of intracranial hypertension (ICH) in patients with severe TBI.

RESULTS

This study identified a total of 18 studies involving hypothermia for control of ICP; 13 were randomized controlled trials (RCT) and five were observational studies. TH (32-34°C) was effective in controlling ICH in all studies. In the 13 RCT, ICP in the TH group was always significantly lower than ICP in the normothermia group. In the five observational studies, ICP during TH was always significantly lower than prior to inducing TH.

CONCLUSIONS

Pending results from large multi-centre studies evaluating the effect of TH on ICH and outcome, TH should be included as a therapeutic option to control ICP in patients with severe TBI.

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.

Therapeutic hypothermia: benefits, mechanisms and potential clinical applications in neurological, cardiac and kidney injury

Therapeutic hypothermia involves the controlled reduction of core temperature to attenuate the secondary organ damage which occurs following a primary injury. Clinicians have been increasingly using therapeutic hypothermia to prevent or ameliorate various types of neurological injury and more recently for some forms of cardiac injury. In addition, some recent evidence suggests that therapeutic hypothermia may also provide benefit following acute kidney injury. In this review we will examine the potential mechanisms of action and current clinical evidence surrounding the use of therapeutic hypothermia. We will discuss the ideal methodological attributes of future studies using hypothermia to optimise outcomes following organ injury, in particular neurological injury. We will assess the importance of target hypothermic temperature, time to achieve target temperature, duration of cooling, and re-warming rate on outcomes following neurological injury to gain insights into important factors which may also influence the success of hypothermia in other organ injuries, such as the heart and the kidney. Finally, we will examine the potential of therapeutic hypothermia as a future kidney protective therapy.

Hypothermia, immune suppression and SDD: can we have our cake and eat it?

In vitro studies and clinical observations suggest that both accidental and controlled/therapeutic hypothermia have a strong immunosuppressive effect, and that hypothermia increases the risk of infections, especially wound infections and pneumonia. In the previous issue of Critical Care, Kamps and colleagues report that when hypothermia was used for prolonged periods in patients with severe traumatic brain injury in conjunction with selective decontamination of the digestive tract, the risks of infection were the same or lower in patients treated with therapeutic cooling. The risk of infection is widely regarded as the most important danger of therapeutic cooling. The findings of Kamps and colleagues need to be verified in prospective trials and in higher-resistance environments, but raise the possibility of cooling for prolonged periods with greatly reduced risk. We may be able to have our cake and eat it.

What blood temperature for an ex vivo extracorporeal circuit?

Ex vivo circuits are commonly used to evaluate biomaterials or devices used for extracorporeal blood purification. However, various aspects of the ex vivo circuit, apart from the circuit materials, may affect inflammation and coagulation. One such aspect is temperature. The aim of this study was to evaluate the influence of different blood temperature conditions on inflammation parameters in an ex vivo circuit. Blood was collected from 20 healthy volunteers and run through three different experimental conditions for 4 h: a miniaturized ex vivo extracorporeal circuit equipped with a blood warmer set to 37°C, the same circuit without the warmer (23°C), and a tube placed in an incubator at 37°C (no circuit). We measured the granulocyte macrophage colony-stimulating factor, the tumor necrosis factor, and the interleukin (IL)-1β, IL-6, IL-8, and IL-10 concentrations at baseline, 15, 60, 120, and 240 min. Human leukocyte antigen (HLA)-DR, CD11b, CD11a, CD62L, tumor necrosis factor alpha converting enzyme, annexin V expression, and NFkB DNA binding were measured in monocytes and polymorphonuclear neutrophils (PMNs) using flow cytometry at baseline, 120 min, and 240 min. While cytokine production over time was very slight at room temperature, levels increased by more than 100-fold in the two heated conditions. Differences in the expression of some surface markers were also observed between the room temperature circuit and the two heated conditions (CD11b PMN, P < 0.0001; HLA-DR Mono, P=0.0019; and CD11a PMN, P<0.0001). Evolution of annexin V expression was also different over time between the three groups (P=0.0178 for monocytes and P=0.0011 for PMNs). A trend for a greater NFkB DNA binding was observed in the heated conditions. Thus, for ex vivo studies using extracorporeal circuits, heating blood to maintain body temperature results in significant activation of inflammatory cells while hypothermia (room temperature) seems to suppress the leukocyte response. Both strategies may lead to erroneous conclusions, possibly masking some specific effects of the device being studied. Investigators in this field must be aware of the fact that blood temperature is a crucial confounding parameter and the type of "background noise" they will face depending on the strategy adopted.

Matrix metalloproteinases and neurotrauma: evolving roles in injury and reparative processes

Matrix metalloproteinases (MMPs) are involved in a wide range of proteolytic events in fetal development and normal tissue remodeling as well as wound healing and inflammation. In the CNS, they have been implicated in a variety of neurodegenerative diseases ranging from multiple sclerosis to Alzheimer disease and are integral to stroke-related cell damage. Although studies implicate increased activity of MMPs in pathogenesis in the CNS, there is also a growing literature to support their participation in events that support recovery processes. Here the authors provide a brief overview of MMPs and their regulation, address their complex roles following traumatic injuries to the adult and developing CNS, and consider their time- and context-dependent signatures that influence both injury and reparative processes.

Blood-brain barrier breakdown as a therapeutic target in traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death in young adults and children. The treatment of TBI in the acute phase has improved substantially; however, the prevention and management of long-term complications remain a challenge. Blood-brain barrier (BBB) breakdown has often been documented in patients with TBI, but the role of such vascular pathology in neurological dysfunction has only recently been explored. Animal studies have demonstrated that BBB breakdown is involved in the initiation of transcriptional changes in the neurovascular network that ultimately lead to delayed neuronal dysfunction and degeneration. Brain imaging data have confirmed the high incidence of BBB breakdown in patients with TBI and suggest that such pathology could be used as a biomarker in the clinic and in drug trials. Here, we review the neurological consequences of TBI, focusing on the long-term complications of such injuries. We present the clinical evidence for involvement of BBB breakdown in TBI and examine the primary and secondary mechanisms that underlie such pathology. We go on to consider the consequences of BBB injury, before analyzing potential mechanisms linking vascular pathology to neuronal dysfunction and degeneration, and exploring possible targets for treatment. Finally, we highlight areas for future basic research and clinical studies into TBI.

Progenitor cell therapy for traumatic brain injury: effect of serum osmolarity on cell viability and cytokine production

INTRODUCTION

The potential translation of mesenchymal stem cell (MSC) therapy into a multimodal protocol for traumatic brain injury requires evaluation of viability and cytokine production in a hyperosmolar environment. Optimization of MSC therapy requires delivery to the target area without significant loss of cellular function or viability. No model evaluating the potential efficacy of MSC therapy at varying osmolarities currently exists.

METHODS

Rat MSCs were characterized with flow cytometric immunophenotyping. MSCs (passage 3) were placed in culture with multipotent adult progenitor cell media at varying osmolarities (250, 270, 290, 310, 330, 350 and 370 mOsm) potentially found with hypertonic saline infusion. After culture for 24 h, cellular viability was measured using flow cytometry (n = 6). Next, brain tissue supernatant was harvested from both normal rat brains and injured brains 6 h after cortical injury. Subsequently, MSCs were placed in culture with multipotent adult progenitor cell media +/- 20% normal brain or injured brain supernatant (at the aforementioned osmolarities) and allowed to remain in culture for 24 h (n = 11). At this point, media supernatant cytokine levels were measured using a multiplex cytokine assay system.

RESULTS

MSCs showed no clinically significant difference in viability at 24 h. MSCs cultured with 20% injured brain supernatant showed an decrease in proinflammatory cytokine production (IL-1alpha and IL-1beta) with increasing osmolarity. No difference in anti-inflammatory cytokine production (IL-4 and IL-10) was observed.

CONCLUSION

Progenitor cell therapy for traumatic brain injury may require survival and activity in a hyperosmolar environment. Culture of MSCs in such conditions shows no clinically significant effect on cell viability. In addition, MSC efficacy could potentially be enhanced via a decrease in proinflammatory cytokine production. Overall, a multimodal traumatic brain injury treatment protocol based upon MSC infusion and hypertonic saline therapy would not negatively affect progenitor cell efficacy and could be considered for multicenter clinical trials.

Elevation of matrix metalloproteinases 3 and 9 in cerebrospinal fluid and blood in patients with severe traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) causes an increase in matrix metalloproteinases (MMPs), which are associated with neuroinflammation, blood-brain barrier disruption, hemorrhage, and cell death. We hypothesized that patients with TBI have an increase in MMPs in ventricular cerebrospinal fluid (CSF) and plasma.

METHODS

Patients with TBI and a ventricular catheter were entered into the study. Samples of CSF and plasma were collected at the time of catheter placement and at 24 and 72 hours after admission. Seven TBI patients were entered into the study, with 6 having complete data for analysis. Only patients who had a known time of insult that fell within a 6-hour window from initial insult to ventriculostomy were accepted into the study. Control CSF came from ventricular fluid in patients undergoing shunt placement for normal pressure hydrocephalus. Both MMP-2 and MMP-9 were measured with gelatin zymography and MMP-3 with Western immunoblot.

RESULTS

We found a significant elevation in the levels of the latent form of MMP-9 (92-kD) in the CSF obtained at the time of arrival (P < 0.05). Elevated levels of MMP-2 were detected in plasma at 72 hours, but not in the CSF. Using albumin from both CSF and blood, we calculated the MMP-9 index, which was significantly increased in the CSF, indicating endogenous MMP production. Western immunoblot showed elevated levels of MMP-3 in CSF at all times measured, whereas MMP-3 was not detected in the CSF of normal pressure hydrocephalus.

CONCLUSION

We show that MMPs are increased in the CSF of TBI patients. Although the number of patients was small, the results were robust and clearly demonstrated increases in MMP-3 and MMP-9 in ventricular CSF in TBI patients compared with controls. Although these preliminary results will need to be replicated, we propose that MMPs may be important in blood-brain barrier opening and hemorrhage secondary to brain injury in patients.

Administration of S-nitrosoglutathione after traumatic brain injury protects the neurovascular unit and reduces secondary injury in a rat model of controlled cortical impact

Background

Traumatic brain injury (TBI) is a major cause of preventable death and serious morbidity in young adults. This complex pathological condition is characterized by significant blood brain barrier (BBB) leakage that stems from cerebral ischemia, inflammation, and redox imbalances in the traumatic penumbra of the injured brain. Once trauma has occurred, combating these exacerbations is the keystone of an effective TBI therapy. Following other brain injuries, nitric oxide modulators such as S-nitrosoglutathione (GSNO) maintain not only redox balance but also inhibit the mechanisms of secondary injury. Therefore, we tested whether GSNO shows efficacy in a rat model of experimental TBI.

Methods

TBI was induced by controlled cortical impact (CCI) in adult male rats. GSNO (50 μg/kg body weight) was administered at two hours after CCI. GSNO-treated injured animals (CCI+GSNO group) were compared with vehicle-treated injured animals (CCI+VEH group) in terms of tissue morphology, BBB leakage, edema, inflammation, cell death, and neurological deficit.

Results

Treatment of the TBI animals with GSNO reduced BBB disruption as evidenced by decreased Evan's blue extravasation across brain, infiltration/activation of macrophages (ED1 positive cells), and reduced expression of ICAM-1 and MMP-9. The GSNO treatment also restored CCI-mediated reduced expression of BBB integrity proteins ZO-1 and occludin. GSNO-mediated improvements in tissue histology shown by reduction of lesion size and decreased loss of both myelin (measured by LFB staining) and neurons (assayed by TUNEL) further support the efficacy of GSNO therapy. GSNO-mediated reduced expression of iNOS in macrophages as well as decreased neuronal cell death may be responsible for the histological improvement and reduced exacerbations. In addition to these biochemical and histological improvements, GSNO-treated injured animals recovered neurobehavioral functions as evaluated by the rotarod task and neurological score measurements.

Conclusion

GSNO is a promising candidate to be evaluated in humans after brain trauma because it not only protects the traumatic penumbra from secondary injury and improves overall tissue structure but also maintains the integrity of BBB and reduces neurologic deficits following CCI in a rat model of experimental TBI.

Mechanisms of action, physiological effects, and complications of hypothermia

BACKGROUND

Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood.

OBJECTIVE

To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (<or=30 degrees C), moderate hypothermia does not induce arrhythmias; indeed, the evidence suggests that arrhythmias can be prevented and/or more easily treated under hypothermic conditions.

CONCLUSIONS

Therapeutic hypothermia is a highly promising treatment, but the potential side effects need to be properly managed particularly if prolonged treatment periods are required. Understanding the underlying mechanisms, awareness of physiological changes associated with cooling, and prevention of potential side effects are all key factors for its effective clinical usage.

Dymanics of matrix-metalloproteinase 9 after brain trauma--results of a pilot study

BACKGROUND

Secondary brain injury contributes to poor outcome for patients sustaining brain trauma. Matrix metalloproteinase-9 (MMP-9) is a potential marker, as well as effector of secondary brain injury. This enzyme degrades components of extracellular matrix, and thus it can contribute to blood-brain barrier disruption.

METHODS

We studied dynamics of MMP-9 in jugular venous blood of 15 patients sustaining either an isolated head injury or a head injury as a part of major trauma, and requiring intensive care (Glasgow Coma Scale <8 at the time of admission). Blood samples were taken at the 1st, 3rd and 5th day, levels of MMP-9 in plasma were assessed using ELISA. Outcome quality was assessed at the time of discharge from our hospital.

FINDINGS

Our results show an increase of MMP-9 levels on the 1st day after the brain trauma, followed by a drop on the 3rd day and a rise on day 5. This biphasic time-course was observed in all patients, but no statistically significant differences between each group (major trauma vs. isolated brain trauma, good outcome vs. poor outcome) were found.

CONCLUSIONS

Initially increased MMP-9 levels in the 1st posttraumatic day is probably related to transient blood-brain barrier dysruption. The decrease of MMP-9 levels observed on the 3rd day can be explained by restoration of blood-brain barrier integrity and its reduced permeability. The second rise of MMP-9 levels observed in the 5th day probably indicates a developing secondary brain injury during which MMP-9 is produced in the brain as a part of an inflammatory response.

RESULTS

of our study suggest that MMP-9 could play an important role in pathogenesis of secondary brain injury.

Quantitative analyses of matrix metalloproteinase activity after traumatic brain injury in adult rats

Recent laboratory evidence implicates matrix metalloproteinases (MMPs) as playing a pivotal role in ischemic and traumatic brain injuries (TBI). Here, quantitative real-time PCR analyses revealed that brains from TBI rats displayed significantly elevated MMP-9 expression at 24 h post-TBI, which remained upregulated at least until 48 h after injury. Immunohistochemical analyses similarly revealed significantly increased MMP-9 immunoreactivity at 24 and 48 h post-TBI. These results demonstrate that alterations in MMPs (i.e., MMP-9) commenced immediately after TBI, suggesting that treatment strategies designed to maintain MMP integrity should be initiated in the acute phase of injury.

Therapeutic hypothermia and controlled normothermia in the intensive care unit: practical considerations, side effects, and cooling methods

BACKGROUND

Hypothermia is being used with increasing frequency to prevent or mitigate various types of neurologic injury. In addition, symptomatic fever control is becoming an increasingly accepted goal of therapy in patients with neurocritical illness. However, effectively controlling fever and inducing hypothermia poses special challenges to the intensive care unit team and others involved in the care of critically ill patients.

OBJECTIVE

To discuss practical aspects and pitfalls of therapeutic temperature management in critically ill patients, and to review the currently available cooling methods.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

Cooling can be divided into three distinct phases: induction, maintenance, and rewarming. Each has its own risks and management problems. A number of cooling devices that have reached the market in recent years enable reliable maintenance and slow and controlled rewarming. In the induction phase, rapid cooling rates can be achieved by combining cold fluid infusion (1500-3000 mL 4 degrees C saline or Ringer's lactate) with an invasive or surface cooling device. Rapid induction decreases the risks and consequences of short-term side effects, such as shivering and metabolic disorders. Cardiovascular effects include bradycardia and a rise in blood pressure. Hypothermia's effect on myocardial contractility is variable (depending on heart rate and filling pressure); in most patients myocardial contractility will increase, although mild diastolic dysfunction can develop in some patients. A risk of clinically significant arrhythmias occurs only if core temperature decreases below 30 degrees C. The most important long-term side effects of hypothermia are infections (usually of the respiratory tract or wounds) and bedsores.

CONCLUSIONS

Temperature management and hypothermia induction are gaining importance in critical care medicine. Intensive care unit physicians, critical care nurses, and others (emergency physicians, neurologists, and cardiologists) should be familiar with the physiologic effects, current indications, techniques, complications and practical issues of temperature management, and induced hypothermia. In experienced hands the technique is safe and highly effective.

Multiplex assessment of serum biomarker concentrations in well-appearing children with inflicted traumatic brain injury

Proper diagnosis of mild inflicted traumatic brain injury (ITBI) is difficult; children often present without a history of trauma and with nonspecific symptoms, such as vomiting. Previous studies suggest that biomarkers may be able to screen for brain injury in this population, but these studies focused on only a few biomarkers. We hypothesized that using multiplex bead technology we would be able to identify multiple differences in the serum biomarker profile between in children with ITBI and those without brain injury. We compared the concentrations of 44 serum biomarkers in 16 infants with mild ITBI and 20 infants without brain injury. There were significant group differences in the concentrations of nine of the 44 markers. Vascular cellular adhesion molecule (VCAM) (p < 0.00) and IL-6 (IL-6) (p < 0.00) had the most significant group differences; IL-6 was higher after ITBI, whereas VCAM was lower. Using VCAM and IL-6 in classification algorithms, we could discriminate the groups with a sensitivity and specificity of 87% and 90%, respectively. The results suggest significant changes in the serum biomarker profile after mild ITBI. Future research is needed to determine whether these biomarkers can screen for brain injury in infants with nonspecific symptoms.

Moderate and severe traumatic brain injury induce early overexpression of systemic and brain gelatinases

OBJECTIVE

Recent experimental evidence suggests that matrix metalloproteinases (MMPs) are implicated in the pathophysiology of traumatic brain injury (TBI) by increasing blood-brain barrier permeability and exacerbating posttraumatic edema. We examined the acute profile of MMP-2 and MMP-9 in the plasma of patients with moderate or severe TBI and in the brain extracellular fluid (ECF).

DESIGN

Prospective observational study.

SETTING

Neurotraumatology intensive care unit of a tertiary university hospital.

PATIENTS

Twenty patients with moderate or severe TBI were included and three groups were used as controls: 20 patients with a mild head injury and normal CT scan, 15 moderate polytrauma patients without TBI, and 20 healthy volunteers.

INTERVENTIONS

Plasma samples were collected within the first 12[Symbol: see text]h and at 24[Symbol: see text]h post-injury. Simultaneous brain microdialysate and plasma samples were obtained in four moderate-severe TBI patients at additional timepoints: 48, 72, and 96[Symbol: see text]h post-TBI.

MEASUREMENTS AND MAIN RESULTS

Gelatinases (MMP-2 and MMP-9) were measured by gelatin zymography. A significant increase in plasma gelatinases was observed at baseline when compared with healthy volunteers in the study group. This early increase was followed by a significant decrease at 24[Symbol: see text]h post-injury. Brain microdialysis samples presented a similar time profile as plasma samples for both gelatinases.

CONCLUSIONS

High levels of gelatinases were found in plasma and brain ECF in the early phase of TBI, indicating that both local and systemic trauma-induced upregulation of gelatinases in the acute phase might play an important role in the pathophysiology of TBI and could be a future therapeutic target.

Brain contusions induce a strong local overexpression of MMP-9. Results of a pilot study

BACKGROUND

Brain contusions are inflammatory evolutive lesions that induce intracranial pressure increase and edema, contributing to neurological outcome. Matrix metalloproteinases (MMPs) 2 and 9 can degrade the majority of the extracellular matrix components, and are implicated in blood-brain barrier disruption and edema formation. The aim of this study was to investigate MMP-2 and MMP-9 profiles in human brain contusions using zymography.

METHODS

A prospective study was conducted in 20 traumatic brain injury patients where contusion brain tissue was resected. Brain tissues from lobectomies were used as controls. Brain homogenates were analysed by gelatin zymography and in situ zimography was performed to confirm results, on one control and one brain contusion tissue sample.

FINDINGS

MMP-2 and MMP-9 levels were higher in brain contusions when compared to controls. MMP-9 was high during the first 24 hours and at 48 to 96 hours, whereas MMP-2 was slightly high at 24 to 96 hours. In situ zymography confirmed gelatin zymography results. A relation between outcome and MMP-9 levels was found; MMP-9 levels were higher in patients with worst outcome.

CONCLUSIONS

Our results indicate strong time-dependent gelatinase expression primarily from MMP-9, suggesting that the inflammatory response induced by focal lesions should be considered as a new therapeutic target.

Pro-inflammatory cytokine, matrix metalloproteinases and TIMP-1 are involved in wound healing after mastectomy in invasive breast cancer patients

BACKGROUND

Mastectomy provides a good model to study the wound healing process after surgery. The involved factors include selectins, pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), matrix metalloproteinases (MMPs), and their natural inhibitors (TIMPs). In the present study, we observed the kinetic changes of these factors in the process of wound healing after a mastectomy, and analyzed the relationship between these factors and the clinical outcomes.

MATERIALS AND METHODS

Twenty-nine patients, who received a modified radical mastectomy, were recruited to this study. The wound was inspected daily for the presence of flap necrosis, infection and seroma. Drain fluid was collected on days 1, 2 and 5. IL-6, P-selectin, MMP-2, 3, 9 and TIMP-1 were screened by ELISA kits for their impacts on wound healing after mastectomy.

RESULTS

IL-6 demonstrated the highest level on Day 1 after operation and was negatively correlated with MMP-2, which in turn showed a consistently negative correlation with MMP-9 for days 1, 2 and 5. Incidences of seroma formation and skin flap necrosis were 27.6% and 20.7%, respectively. Seroma formation was associated with low MMP-2 levels on Day 5. While skin flap necrosis seemed to correlate with high MMP-2 levels and low levels of MMP-9 and TIMP-1.

CONCLUSION

IL-6, P-selectin, MMP-2, MMP-3, MMP-9 and TIMP-1 are important in the process of wound healing after mastectomy. A low MMP-2 level correlates with the formation of seroma, while MMP-2, MMP-9 and TIMP-1 are associated with skin flap necrosis.

Effects of therapeutic mild hypothermia on patients with severe traumatic brain injury after craniotomy

PURPOSE

We investigated the effects of therapeutic mild hypothermia on patients with severe traumatic brain injury after craniotomy (TBI).

METHODS

Eighty patients with severe TBI after unilateral craniotomy were randomized into a therapeutic hypothermia group with the brain temperature maintained at 33 degrees C to 35 degrees C for 4 days, and a normothermia control group in the intensive care unit. Vital signs, intracranial pressure, serum superoxide dismutase level, Glasgow Outcome Scale scores, and complications were prospectively analyzed.

RESULTS

The mean intracranial pressure values of the therapeutic hypothermia group at 24, 48, and 72 hours after injury were much lower than those of the control group (23.49 +/- 2.38, 24.68 +/- 1.71, and 22.51 +/- 2.44 vs 25.87 +/- 2.18, 25.90 +/- 1.86, and 24.57 +/- 3.95 mm Hg; P = .000, .000, and .003, respectively). The mean serum superoxide dismutase levels of the therapeutic hypothermia group at days 3 and 7 were much higher than those of the control group at the same time point (533.0 +/- 103.4 and 600.5 +/- 82.9 vs 458.7 +/- 68.1 and 497.0 +/- 57.3 mug/L, respectively; P = .000). The percentage of favorable neurologic outcome 1 year after injury was 70.0% and 47.5%, respectively (P = .041). Complications, including pulmonary infections (57.5% in the therapeutic hypothermia group vs 32.5% in the control group; P = .025) were managed without severe sequelae.

CONCLUSIONS

Therapeutic mild hypothermia provides a promising way in the intensive care unit for patients with severe TBI after craniotomy.

Relationships between free radical levels during carotid endarterectomy and markers of arteriosclerotic disease

BACKGROUND

Free radical production is elevated in jugular venous blood emerging from the brain in conjunction with carotid endarterectomy. This study explores the relationships between markers for lesion progression in arteriosclerosis, production of radicals and clinical characteristics.

METHODS

The radical production during carotid endarterectomy was studied in 13 patients with an ex vivo spin trap method using OXANOH as a spin trap. MCP-1, ICAM-1, MMP-9 and oxLDL were determined in venous blood samples before, during and after clamping of the carotid artery. Principal component analysis (PCA) as well as partial least square regression analysis (PLS) was applied to interpret the data.

RESULTS

PCA and PLS analysis revealed that high values of MMP-9 and low values of ICAM-1 were associated with high radical production whereas MCP-1 and oxLDL were not correlated to radical production. MMP-9 was elevated at diabetes, high haemoglobin, high leucocyte counts and thrombocyte counts as well as at contralateral stenosis, whereas ICAM-1 showed reversed relationships to these clinical variables. MCP-1 increased during surgery.

CONCLUSIONS

The main finding in our study is that MMP-9 in plasma is asscociated with radical production during carotid endarterectomy, suggesting that this enzyme might be involved in the pathogenesis of brain damage in conjunction with ischaemia-reperfusion.

Influence of therapeutic hypothermia on matrix metalloproteinase activity after traumatic brain injury in rats

Recent evidence suggests that matrix metalloproteinases (MMPs) contribute to acute edema and lesion formation following ischemic and traumatic brain injuries (TBI). Experimental and clinical studies have also reported the beneficial effects of posttraumatic hypothermia on histopathological and behavioral outcome. The purpose of this study was to determine whether therapeutic hypothermia would affect the activity of MMPs after TBI. Male Sprague-Dawley rats were traumatized by moderate parasagittal fluid-percussion (F-P) brain injury. Seven groups (n=5/group) of animals were investigated: sham-operated, TBI with normothermia (37 degrees C), and TBI with hypothermia (33 degrees C). Normothermia animals were killed at 4, 24, 72 h and 5 days, and hypothermia animals at 24 or 72 h. Brain temperature was reduced to target temperature 30 mins after trauma and maintained for 4 h. Ipsilateral and contralateral cortical, hippocampal, and thalamic regions were analyzed by gelatin and in situ zymography. In traumatized normothermic animals, TBI significantly (P<0.005) increased MMP-9 levels in ipsilateral (right) cortical and hippocampal regions, compared with contralateral or sham animals, beginning at 4 h and persisting to 5 days. At 1, 3, and 5 days after TBI, significant increases in MMP-2 levels were observed. In contrast to these findings observed with normothermia, posttraumatic hypothermia significantly reduced MMP-9 levels. Hypothermic treatment, however, did not affect the delayed activation of MMP-2. Clarifying the mechanisms underlying the beneficial effects of posttraumatic hypothermia is an active area of research. Posttraumatic hypothermia may attenuate the deleterious consequences of brain trauma by reducing MMP activation acutely.