Changes in circulating inflammatory cells and the relationship to secondary brain injury in patients with craniocerebral injury

BACKGROUND：Recent studies have indicated that reactive encephalitis plays an important role in secondary tissue damage after craniocerebral injury. OBJECTIVE： To observe changes in white blood cells （WBC） and polymorphonuclear neutrophils （PMN） in peripheral blood, and to determine their role in secondary brain insult in patients with craniocerebral injury. DESIGN, TIME AND SETTING： A case-control study at the Department of Neurosurgery of the Affiliated Hospital North Sichuan University of Medical Sciences between August 2007 and May 2008. PARTICIPANTS： Sixty-three patients, admitted within 24 hours after craniocerebral injury and who received no surgery, were included in the study. The cohort consisted of 41 males and 22 females, aged 9–72 years, with an average age of 42 years. Ten healthy volunteers, selected from the Department of Neurosurgery, were designated as the control group. METHODS： WBC and PMN from the peripheral blood were measured 0, 24, 48, 72, and 168 hours after admission to hospital. The Glasgow coma scale, area of cerebral hemorrhage, and degree of brain edema were simultaneously determined. The Glasgow outcome scale was evaluated six months after injury. The relationship between changes in WBC and PMN were analyzed. Sixty-three patients were divided into 0, 24, 48, 72, and 168 hours groups, with admission time to hospital as the determining factor. As controls, WBC and PMN of peripheral blood were also detected in 10 healthy volunteers. MAIN OUTCOME MEASURES： The main outcome measures were WBC and PMN counts in the peripheral blood at 0, 24, 48, 72, and 168 hours after admission to hospital, the mutual relationship between GCS, WBC and PMN, and changes in brain hemorrhage volume and edema size. RESULTS： WBC peaked at 24 hours after injury, and PMN peaked at 48 hours after injury （P 〈 0.01）. These measures negatively correlated to the Glasgow coma scale （r = -0.657, -0.541, respectively, P 〈 0.05）. In patients with Glasgow coma sale 〈 8, WBC and PMN were significantly higher than in the patients with GCS ≥ 8 （P 〈 0.05）. Cerebral hemorrhage reached a peak at 24 hours after injury, and the degree of brain edema was maximal at 168 hours after injury. WBC and PMN counts were positively correlated to cerebral hemorrhage volume and brain edema size （P 〈 0.05）. CONCLUSION： WBC and PMN counts significantly increased after craniocerebral injury and exhibited a correlation with the GCS score, volume of hemorrhage and edema, and Glasgow outcome scale.

Changes in platelet parameters and secondary brain injury in acute craniocerebral trauma

Changes in platelet parameters are important in secondary brain injury in acute craniocerebral trauma We selected 163 patients with craniocerebral trauma who were admitted within 24 hours with nonoperative therapy. Platelet parameters of 40 healthy subjects served as controls. Platelet number was decreased, while mean platelet volume and platelet distribution width values were increased, at 1 and 3 days after injury. Platelet number was lower and mean platelet volume and platelet distribution width were larger in patients with traumatic cerebral infarction and those in Glasgow Coma Scale score 〈 8 group. Platelet number was negatively correlated to volume of cerebral edema, but positively correlated to Glasgow Outcome Scale score. These data indicate that changes in platelet parameters may be utilized to indicate the state of central nervous system injury and patient prognosis .

Neutrophil-derived interleukin-17A participates in neuroinflammation induced by traumatic brain injury

After brain injury, infiltration and abnormal activation of neutrophils damages brain tissue and worsens inflammation, but the mediators that connect activated neutrophils with neuroinflammation have not yet been fully clarified. To identify regulators of neutrophil-mediated neuroinflammation after traumatic brain injury, a mouse model of traumatic brain injury was established by controlled cortical impact. At 7 days post-injury(sub-acute phase), genome-wide transcriptomic data showed that interleukin 17 A-associated signaling pathways were markedly upregulated, suggesting that interleukin 17 A may be involved in neuroinflammation. Double immunofluorescence staining showed that interleukin 17 A was largely secreted by neutrophils rather than by glial cells and neurons. Furthermore, nuclear factor-kappaB and Stat3, both of which are important effectors in interleukin 17 A-mediated proinflammatory responses, were significantly activated. Collectively, our findings suggest that neutrophil-derived interleukin 17 A participates in neutrophil-mediated neuroinflammation during the subacute phase of traumatic brain injury. Therefore, interleukin 17 A may be a promising therapeutic target for traumatic brain injury.

Inhibition of endoplasmic reticulum stress alleviates secondary injury after traumatic brain injury

Apoptosis after traumatic brain injury has been shown to be a major factor influencing prognosis and outcome. Endoplasmic reticulum stress may be involved in mitochondrial mediated neuronal apoptosis. Therefore, endoplasmic reticulum stress has become an important mechanism of secondary injury after traumatic brain injury. In this study, a rat model of traumatic brain injury was established by lateral fluid percussion injury. Fluorescence assays were used to measure reactive oxygen species content in the cerebral cortex. Western blot assays were used to determine expression of endoplasmic reticulum stress-related proteins. Hematoxylin-eosin staining was used to detect pathological changes in the cerebral cortex. Transmission electron microscopy was used to measure ultrastructural changes in the endoplasmic reticulum and mitochondria. Our results showed activation of the endoplasmic reticulum stress-related unfolded protein response. Meanwhile, both the endoplasmic reticulum stress response and mitochondrial apoptotic pathway were activated at different stages post-traumatic brain injury. Furthermore, pretreatment with the endoplasmic reticulum stress inhibitor, salubrinal（1 mg/kg）, by intraperitoneal injection 30 minutes before injury significantly inhibited the endoplasmic reticulum stress response and reduced apoptosis. Moreover, salubrinal promoted recovery of mitochondrial function and inhibited activation of the mitochondrial apoptotic pathway post-traumatic brain injury. These results suggest that endoplasmic reticulum stress might be a key factor for secondary brain injury post-traumatic brain injury.

Acrolein Aggravates Secondary Brain Injury After Intracerebral Hemorrhage Through Drp1-Mediated Mitochondrial Oxidative Damage in Mice

Clinical advances in the treatment of intracranial hemorrhage(ICH)are restricted by the incomplete understanding of the molecular mechanisms contributing to secondary brain injury.Acrolein is a highly active unsaturated aldehyde which has been implicated in many nervous system diseases.Our results indicated a significant increase in the level of acrolein after ICH in mouse brain.In primary neurons,acrolein induced an increase in mitochondrial fragmentation,loss of mitochondrial membrane potential,generation of reactive oxidative species,and release of mitochondrial cytochrome c.Mechanistically,acrolein facilitated the translocation of dynaminrelated protein 1(Drpl)from the cytoplasm onto the mitochondrial membrane and led to excessive mitochondrial fission.Further studies found that treatment with hydralazine(an acrolein scavenger)significantly reversed Drpl translocation and the morphological damage of mitochondria after ICH.In parallel,the neural apoptosis,brain edema,and neurological functional deficits induced by ICH were also remarkably alleviated.In conclusion,our results identify acrolein as an important contributor to the secondary brain injury following ICH.Meanwhile,we uncovered a novel mechanism by which Drpl-mediated mitochondrial oxidative damage is involved in acroleininduced brain injury.

Dynamic changes in growth factor levels over a 7-day period predict the functional outcomes of traumatic brain injury

Traumatic brain injury（TBI） can result in poor functional outcomes and death, and overall outcomes are varied. Growth factors, such as angiopoietin-1（Ang-1）, vascular endothelial growth factor（VEGF）, and granulocyte-colony stimulating factor（G-CSF）, play important roles in the neurological functions. This study investigated the relationship between serum growth factor levels and long-term outcomes after TBI. Blood samples from 55 patients were collected at 1, 3 and 7 days after TBI. Blood samples from 39 healthy controls were collected as a control group. Serum Ang-1, G-CSF, and VEGF levels were measured using ELISA. Patients were monitored for 3 months using the Glasgow Outcome Scale-Extended（GOSE）. Patients having a GOSE score of 〉 5 at 3 months were categorized as a good outcome, and patients with a GOSE score of 1-5 were categorized as a bad outcome. Our data demonstrated that TBI patients showed significantly increased growth factor levels within 7 days compared with healthy controls. Serum levels of Ang-1 at 1 and 7 days and G-CSF levels at 7 days were significantly higher in patients with good outcomes than in patients with poor outcomes. VEGF levels at 7 days were remarkably higher in patients with poor outcomes than in patients with good outcomes. Receiver operating characteristic analysis showed that the best cut-off points of serum growth factor levels at 7 days to predict functional outcome were 1,333 pg/mL for VEGF, 447.2 pg/mL for G-CSF, and 90.6 ng/mL for Ang-1. These data suggest that patients with elevated levels of serum Ang-1, G-CSF, and decreased VEGF levels had a better prognosis in the acute phase of TBI（within 7 days）. This study was registered with the Chinese Clinical Trial Registry（registration number： ChiCTR1800018251） on September 7, 2018.

Mitophagy in intracerebral hemorrhage:a new target for therapeutic intervention

Intracerebral hemorrhage is a life-threatening condition with a high fatality rate and severe sequelae.However,there is currently no treatment available for intracerebral hemorrhage,unlike for other stroke subtypes.Recent studies have indicated that mitochondrial dysfunction and mitophagy likely relate to the pathophysiology of intracerebral hemorrhage.Mitophagy,or selective autophagy of mitochondria,is an essential pathway to preserve mitochondrial homeostasis by clearing up damaged mitochondria.Mitophagy markedly contributes to the reduction of secondary brain injury caused by mitochondrial dysfunction after intracerebral hemorrhage.This review provides an overview of the mitochondrial dysfunction that occurs after intracerebral hemorrhage and the underlying mechanisms regarding how mitophagy regulates it,and discusses the new direction of therapeutic strategies targeting mitophagy for intracerebral hemorrhage,aiming to determine the close connection between mitophagy and intracerebral hemorrhage and identify new therapies to modulate mitophagy after intracerebral hemorrhage.In conclusion,although only a small number of drugs modulating mitophagy in intracerebral hemorrhage have been found thus far,most of which are in the preclinical stage and require further investigation,mitophagy is still a very valid and promising therapeutic target for intracerebral hemorrhage in the long run.

Knockdown of NADPH oxidase 4 reduces mitochondrial oxidative stress and neuronal pyroptosis following intracerebral hemorrhage

Intracerebral hemorrhage is often accompanied by oxidative stress induced by reactive oxygen species,which causes abnormal mitochondrial function and secondary reactive oxygen species generation.This creates a vicious cycle leading to reactive oxygen species accumulation,resulting in progression of the pathological process.Therefore,breaking the cycle to inhibit reactive oxygen species accumulation is critical for reducing neuronal death after intracerebral hemorrhage.Our previous study found that increased expression of nicotinamide adenine dinucleotide phosphate oxidase 4(NADPH oxidase 4,NOX4)led to neuronal apoptosis and damage to the blood-brain barrier after intracerebral hemorrhage.The purpose of this study was to investigate the role of NOX4 in the circle involving the neuronal tolerance to oxidative stress,mitochondrial reactive oxygen species and modes of neuronal death other than apoptosis after intracerebral hemorrhage.We found that NOX4 knockdown by adeno-associated virus(AAV-NOX4)in rats enhanced neuronal tolerance to oxidative stress,enabling them to better resist the oxidative stress caused by intracerebral hemorrhage.Knockdown of NOX4 also reduced the production of reactive oxygen species in the mitochondria,relieved mitochondrial damage,prevented secondary reactive oxygen species accumulation,reduced neuronal pyroptosis and contributed to relieving secondary brain injury after intracerebral hemorrhage in rats.Finally,we used a mitochondria-targeted superoxide dismutase mimetic to explore the relationship between reactive oxygen species and NOX4.The mitochondria-targeted superoxide dismutase mimetic inhibited the expression of NOX4 and neuronal pyroptosis,which is similar to the effect of AAV-NOX4.This indicates that NOX4 is likely to be an important target for inhibiting mitochondrial reactive oxygen species production,and NOX4 inhibitors can be used to alleviate oxidative stress response induced by intracerebral hemorrhage.

Oxidized low-density lipoprotein receptor 1:a novel potential therapeutic target for intracerebral hemorrhage

Oxidized low-density lipoprotein receptor 1(OLR1)is upregulated in neurons and participates in hypertension-induced neuronal apoptosis.OLR1 deletion exerts protective effects on cerebral damage induced by hypertensive-induced stroke.Therefore,OLR1 is likely involved in the progress of intracerebral hemorrhage.In this study,we examined the potential role of OLR1 in intracerebral hemorrhage using a rat model.OLR1 small interfering RNA(10μL;50 pmol/μL)was injected into the right basal ganglia to knock down OLR1.Twenty-four hours later,0.5 U collagenase type VII was injected to induce intracerebral hemorrhage.We found that knockdown of OLR1 attenuated neurological behavior impairment in rats with intracerebral hemorrhage and reduced hematoma,neuron loss,inflammatory reaction,and oxidative stress in rat brain tissue.We also found that silencing of OLR1 suppressed ferroptosis induced by intracerebral hemorrhage and the p38 signaling pathway.Therefore,silencing OLR1 exhibits protective effects against secondary injury of intracerebral hemorrhage.These findings suggest that OLR1 may be a novel potential therapeutic target for intracerebral hemorrhage.

Myeloperoxidase: a new target for the treatment of stroke?

Myeloperoxidase is an important inflammatory factor in the myeloid system,primarily expressed in neutrophils and microglia.Myeloperoxidase and its active products participate in the occurrence and development of hemorrhagic and ischemic stroke,including damage to the blood-brain barrier and brain.As a specific inflammatory marker,myeloperoxidase can be used in the evaluation of vascular disease occurrence and development in stroke,and a large amount of experimental and clinical data has indicated that the inhibition or lack of myeloperoxidase has positive impacts on stroke prognosis.Many studies have also shown that there is a correlation between the overexpression of myeloperoxidase and the risk of stroke.The occurrence of stroke not only refers to the first occurrence but also includes recurrence.Therefore,myeloperoxidase is significant for the clinical evaluation and prognosis of stroke.This paper reviews the potential role played by myeloperoxidase in the development of vascular injury and secondary brain injury after stroke and explores the effects of inhibiting myeloperoxidase on stroke prognosis.This paper also analyzes the significance of myeloperoxidase etiology in the occurrence and development of stroke and discusses whether myeloperoxidase can be used as a target for the treatment and prediction of stroke.