Preinjury alcohol exposure attenuates the neuroinflammatory response to traumatic brain injury

Alcohol intake before injury and functional and survival outcomes after traumatic brain injury: Pan-Asian trauma outcomes study (PATOS)

There are controversies about the effects of alcohol intake shortly before injury on prognosis of traumatic brain injury (TBI) patients. We investigated the association between alcohol intake and functional/survival outcomes in TBI patients, and whether this effect varied according to age and sex. This was a prospective international multicenter cohort study using the Pan-Asian trauma outcomes study registry in Asian-Pacific countries, conducted on adult patients with TBI who visited participating hospitals. The main exposure variable was alcohol intake before injury, and the main outcomes were poor functional recovery (modified Rankin Scale score, 4-6) and in-hospital mortality. Multivariable logistic regression analyses were conducted to estimate the effects of alcohol intake on study outcomes. Interaction analysis between alcohol intake and age/sex were also performed. Among the study population of 12,451, 3263 (26.2%) patients consumed alcohol before injury. In multivariable logistic regression analysis, alcohol intake was associated with lower odds for poor functional recovery [4.4% vs 6.6%, a odds ratio (95% confidence interval): 0.68 (0.56-0.83)] and in-hospital mortality (1.9% vs 3.1%, 0.64 [0.48-0.86]). The alcohol intake had interaction effects with sex for poor functional recovery: 0.59 (0.45-0.75) for male and 0.94 (0.60-1.49) for female (P for-interaction < .01), whereas there were no interaction between alcohol intake and age. In TBI patients, alcohol intake before injury was associated with lower odds of poor functional recovery and in-hospital mortality, and these effects were maintained in the male group in the interaction analyses.

Loss of Consciousness and Righting Reflex Following Traumatic Brain Injury: Predictors of Post-Injury Symptom Development (A Narrative Review)

Identifying predictors for individuals vulnerable to the adverse effects of traumatic brain injury (TBI) remains an ongoing research pursuit. This is especially important for patients with mild TBI (mTBI), whose condition is often overlooked. TBI severity in humans is determined by several criteria, including the duration of loss of consciousness (LOC): LOC < 30 min for mTBI and LOC > 30 min for moderate-to-severe TBI. However, in experimental TBI models, there is no standard guideline for assessing the severity of TBI. One commonly used metric is the loss of righting reflex (LRR), a rodent analogue of LOC. However, LRR is highly variable across studies and rodents, making strict numeric cutoffs difficult to define. Instead, LRR may best be used as predictor of symptom development and severity. This review summarizes the current knowledge on the associations between LOC and outcomes after mTBI in humans and between LRR and outcomes after experimental TBI in rodents. In clinical literature, LOC following mTBI is associated with various adverse outcome measures, such as cognitive and memory deficits; psychiatric disorders; physical symptoms; and brain abnormalities associated with the aforementioned impairments. In preclinical studies, longer LRR following TBI is associated with greater motor and sensorimotor impairments; cognitive and memory impairments; peripheral and neuropathology; and physiologic abnormalities. Because of the similarities in associations, LRR in experimental TBI models may serve as a useful proxy for LOC to contribute to the ongoing development of evidence-based personalized treatment strategies for patients sustaining head trauma. Analysis of highly symptomatic rodents may shed light on the biological underpinnings of symptom development after rodent TBI, which may translate to therapeutic targets for mTBI in humans.

Autopsy-Diagnosed Injury Deaths in Persons With Acute or Chronic Alcohol Use: A Review of 1000 Deaths With History of Alcohol Use

ABSTRACT

Acute and chronic alcohol use is associated with injury, and autopsies may be performed to ascertain injury deaths in persons with acute or chronic alcohol use. This study sought to determine how many decedents with a history of acute or chronic alcohol use had an internal physical injury diagnosed only at autopsy that caused or contributed to the death. The study reviewed medicolegal investigation and autopsy reports at the New York City Office of Chief Medical Examiner between January 1 and October 11, 2018, to identify 1000 consecutive persons with suspected acute or chronic alcohol use who were autopsied to ascertain whether internal physical injury caused or contributed to the death. Of 1000 persons with known or suspected acute or chronic alcohol use, 390 (39.0%) had an external injury. Although 115 (11.5%) had an internal injury at autopsy, only 29 (2.9%) had an injury that caused or contributed to the death. Only 1 decedent had an internal injury that caused the death with no associated external evidence of injury (0.1%). This study demonstrates the rarity of occult lethal injury diagnosed at autopsy in persons with acute or chronic alcohol use.

Aspirin Administration Mitigates Platelet Hyperaggregability After Splenectomy in a Murine Model

INTRODUCTION

Patients who undergo splenectomy (SPLN) have an estimated 10%-35% risk of venous thromboembolic events; however, the underlying mechanism and strategy for prevention have yet to be identified. The goals of this study were to 1) investigate platelet aggregation after SPLN, 2) examine if aspirin administration could mitigate this effect, and 3) determine if concomitant hemorrhage would affect post-SPLN platelet function and response to aspirin.

METHODS

Murine models of operative SPLN and submandibular bleed (SMB) were utilized. Mice were randomized to eight groups as follows: untouched, SPLN, sham (laparotomy only), SMB, SPLN + SMB, SPLN + aspirin (ASA), SMB + ASA, and SPLN + SMB + ASA. Aspirin (50 mg/kg) was administered on postoperative days (PODs) one and two via oral gavage. Mice were euthanized on POD 3, platelet counts were obtained, and blood samples were analyzed via rotational thromboelastometry and impedance aggregometry with adenosine diphosphate (ADP) and arachidonic acid (AA) as agonists.

RESULTS

By POD 3, SPLN mice displayed a significant thrombocytosis compared to untouched, SMB, and sham SPLN mice. Clotting time and clot formation time were significantly decreased in SPLN and SPLN + SMB cohorts compared to untouched and sham controls with elevated mean clot firmness. SPLN mice also displayed a significant increase in ADP- and AA-mediated platelet aggregability compared to untouched controls, SMB, and SPLN + SMB. ASA significantly decreased platelet aggregation via both ADP and AA signaling in SPLN and SPLN + SMB cohorts without affecting viscoelastic coagulation testing.

CONCLUSIONS

Platelet hyperaggregability after SPLN is mediated by both ADP and AA signaling. Early aspirin administration may prevent increased platelet aggregation exacerbated after polytrauma.

Role of statins in regulating molecular pathways following traumatic brain injury: A system pharmacology study

Traumatic brain injury (TBI) is a serious disorder with debilitating physical and psychological complications. Previous studies have indicated that genetic factors have a critical role in modulating the secondary phase of injury in TBI. Statins have interesting pleiotropic properties such as antiapoptotic, antioxidative, and anti-inflammatory effects, which make them a suitable class of drugs for repurposing in TBI. In this study, we aimed to explore how statins modulate proteins and pathways involved in TBI using system pharmacology. We first explored the target associations with statins in two databases to discover critical clustering groups, candidate hub and critical hub genes in the network of TBI, and the possible connections of statins with TBI-related genes. Our results showed 1763 genes associated with TBI. Subsequently, the analysis of centralities in the PPI network displayed 55 candidate hub genes and 15 hub genes. Besides, MCODE analysis based on threshold score:10 determined four modular clusters. Intersection analysis of genes related to TBI and statins demonstrated 204 shared proteins, which suggested that statins influence 31 candidate hub and 9 hub genes. Moreover, statins had the highest interaction with MCODE1. The biological processes of the 31 shared proteins are related to gene expression, inflammation, antioxidant activity, and cell proliferation. Biological enriched pathways showed Programmed Cell Death proteins, AGE-RAGE signaling pathway, C-type lectin receptor signalling pathway, and MAPK signaling pathway as top clusters. In conclusion, statins could target several critical post-TBI genes mainly involved in inflammation and apoptosis, supporting the previous research results as a potential therapeutic agent.

Fast Maturation of Splenic Dendritic Cells Upon TBI Is Associated With FLT3/FLT3L Signaling

The consequences of systemic inflammation are a significant burden after traumatic brain injury (TBI), with almost all organs affected. This response consists of inflammation and concurrent immunosuppression after injury. One of the main immune regulatory organs, the spleen, is highly interactive with the brain. Along this brain–spleen axis, both nerve fibers as well as brain-derived circulating mediators have been shown to interact directly with splenic immune cells. One of the most significant comorbidities in TBI is acute ethanol intoxication (EI), with almost 40% of patients showing a positive blood alcohol level (BAL) upon injury. EI by itself has been shown to reduce proinflammatory mediators dose-dependently and enhance anti-inflammatory mediators in the spleen. However, how the splenic immune modulatory effect reacts to EI in TBI remains unclear. Therefore, we investigated early splenic immune responses after TBI with and without EI, using gene expression screening of cytokines and chemokines and fluorescence staining of thin spleen sections to investigate cellular mechanisms in immune cells. We found a strong FLT3/FLT3L induction 3 h after TBI, which was enhanced by EI. The FLT3L induction resulted in phosphorylation of FLT3 in CD11c+ dendritic cells, which enhanced protein synthesis, maturation process, and the immunity of dendritic cells, shown by pS6, peIF2A, MHC-II, LAMP1, and CD68 by immunostaining and TNF-α expression by in-situ hybridization. In conclusion, these data indicate that TBI induces a fast maturation and immunity of dendritic cells which is associated with FLT3/FLT3L signaling and which is enhanced by EI prior to TBI.

Differential effect of ethanol intoxication on peripheral markers of cerebral injury in murine blunt traumatic brain injury

Background

Blood-based biomarkers have proven to be a reliable measure of the severity and outcome of traumatic brain injury (TBI) in both murine models and patients. In particular, neuron-specific enolase (NSE), neurofilament light (NFL) and S100 beta (S100B) have been investigated in the clinical setting post-injury. Ethanol intoxication (EI) remains a significant comorbidity in TBI, with 30–40% of patients having a positive blood alcohol concentration post-TBI. The effect of ethanol on blood-based biomarkers for the prognosis and diagnosis of TBI remains unclear. In this study, we investigated the effect of EI on NSE, NFL and S100B and their correlation with blood–brain barrier integrity in a murine model of TBI.

Methods

We used ultra-sensitive single-molecule array technology and enzyme-linked immunosorbent assay methods to measure NFL, NSE, S100B and claudin-5 concentrations in plasma 3 hours post-TBI.

Results

We showed that NFL, NSE and S100B were increased at 3 hours post-TBI. Interestingly, ethanol blood concentrations showed an inverse correlation with NSE but not with NFL or S100B. Claudin-5 levels were increased post-injury but no difference was detected compared to ethanol pretreatment. The increase in claudin-5 post-TBI was correlated with NFL but not with NSE or S100B.

Conclusions

Ethanol induces an effect on biomarker release in the bloodstream that is different from TBI not influenced by alcohol. This could be the basis of investigations into humans.

Association between alcohol intoxication and mortality in severe traumatic brain injury in the emergency department: a retrospective cohort

BACKGROUND

Acute alcohol intoxication is very common in patients with severe traumatic brain injury (TBI). Whether there is an independent association between alcohol intoxication and mortality is debated. This study hypothesized that alcohol intoxication is independently associated with less mortality after severe TBI (sTBI).

METHODS

This retrospective observational cohort study included all patients with sTBI [head-Abbreviated Injury Score (AIS) ≥3, corresponding to serious head injury or worse] admitted from 1 January 2011 to 31 December 2016 in an academic level I trauma center. Patients were classified as with alcohol intoxication or without intoxication based on blood alcohol concentration or description of alcohol intoxication on admission. The primary endpoint was in-hospital mortality. Multivariable logistic regression analysis, including patient and injury characteristics, was used to assess independent association with alcohol intoxication.

RESULTS

Of the 2865 TBI patients, 715 (25%) suffered from alcohol intoxication. They were younger (mean age 46 vs. 68 years), more often male (80 vs. 57%) and had a lower median Glasgow Coma Scale upon arrival (14 vs. 15) compared to the no-intoxication group. There was no difference in injury severity by head AIS or Rotterdam CT. Alcohol intoxication had an unadjusted association with in-hospital mortality [unadjusted odds ratio (OR) 0.51; 95% confidence interval (CI), 0.38-0.68]; however, there was no independent association after adjusting for potentially confounding patient and injury characteristics (adjusted OR 0.72; 95% CI, 0.48-1.09).

CONCLUSION

In this retrospective study, there was no independent association between alcohol intoxication and higher in-hospital mortality in emergency patients with sTBI.

Effect of ethanol in carbon monoxide poisoning and delayed neurologic sequelae: A prospective observational study

Objectives

Carbon monoxide (CO) is one of the most common poisoning substances, which causes mortality and morbidity worldwide. Delayed neurologic sequelae (DNS) have been reported to occur from several days to months after exposure to CO. Thus, there is a need for prevention, recognition, and treatment of DNS. Patients with CO poisoning as a component of intentional suicide often also consume ethanol, but there is debate regarding its role in DNS. We explored whether ethanol has a neuroprotective effect in CO poisoning.

Methods

This prospective observational study included patients who visited the emergency department from August 2016 to August 2019 due to CO poisoning. After treatment of acute CO poisoning, patients were interviewed by telephone to ascertain whether DNS had occurred within 2 weeks, 1 month, and 3 months from the time of CO exposure.

Results

During the study period, 171 patients were enrolled. 28 patients (16.37%) developed DNS. The initial Glasgow Coma Scale (GCS) scores were 15 (10.5–15) for the non-DNS group and 10 (7–15) for the DNS group (p = 0.002). The ethanol levels were 11.01 ± 17.58 mg/dL and 1.49 ± 2.63 mg/dL for each group (p < 0.001). In multivariate logistic regression analysis, the GCS score had an odds ratio of 0.770 (p < 0.001) and the ethanol level had 0.882 (p < 0.030) for onset of DNS.

Conclusions

Higher ethanol level and higher initial GCS score were associated with lower incidence of DNS. Ethanol could have a neuroprotective effect on the occurrence of DNS in CO poisoning patients.

Combined Effects of Repetitive Mild Traumatic Brain Injury and Alcohol Drinking on the Neuroinflammatory Cytokine Response and Cognitive Behavioral Outcomes

The relationship between alcohol consumption and traumatic brain injury (TBI) often focuses on alcohol consumption increasing the likelihood of incurring a TBI, rather than alcohol use outcomes after TBI. However, patients without a history of an alcohol use disorder can also show increased problem drinking after single or multiple TBIs. Alcohol and mild TBI share diffuse deleterious neurological impacts and cognitive impairments; therefore, the purpose of these studies was to determine if an interaction on brain and behavior outcomes occurs when alcohol is consumed longitudinally after TBI. To examine the impact of mild repetitive TBI (rmTBI) on voluntary alcohol consumption, mice were subjected to four mild TBI or sham procedures over a 2 week period, then offered alcohol (20% v/v) for 2 weeks using the two-bottle choice, drinking in the dark protocol. Following the drinking period, mice were evaluated for neuroinflammatory cytokine response or tested for cognitive and behavioral deficits. Results indicate no difference in alcohol consumption or preference following rmTBI as compared to sham; however, increases in the neuroinflammatory cytokine response due to alcohol consumption and some mild cognitive behavioral deficits after rmTBI and alcohol consumption were observed. These data suggest that the cytokine response to alcohol drinking and rmTBI + alcohol drinking is not necessarily aggregate, but the combination does result in an exacerbation of cognitive behavioral outcomes.

Ethanol Intoxication Alleviates the Inflammatory Response of Remote Organs to Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) may cause damage to distant organs. Acute ethanol intoxication (EI) induces complex local and systemic anti-inflammatory effects and influences the early outcomes of traumatized patients. Here, we evaluated its effects on the BI-induced expression of local inflammatory mediators in the trauma-remote organs the lungs and liver. Male mice were exposed to ethanol as a single oral dose (5g·kg^–1, 32%) before inducing a moderate blunt TBI. Sham groups underwent the same procedures without TBI. Ether 3 or 6h after the TBI, the lung and liver were collected. The gene expression of HMGB1, IL-6, MMP9, IL-1β, and TNF as well as the homogenate protein levels of receptor for advanced glycation end products (RAGE), IL-6, IL-1β, and IL-10 were analyzed. Liver samples were immunohistologically stained for HMGB1. EI decreased the gene expressions of the proinflammatory markers HMGB1, IL-6, and MMP9 in the liver upon TBI. In line with the reduced gene expression, the TBI-induced protein expression of IL-6 in liver tissue homogenates was significantly reduced by EI at 3h after TBI. While the histological HMGB1 expression was enhanced by TBI, the RAGE protein expression in the liver tissue homogenates was diminished after TBI. EI reduced the histological HMGB1 expression and enhanced the hepatic RAGE protein expression at 6h post TBI. With regard to the lungs, EI significantly reduced the gene expressions of HMGB1, IL-6, IL-1β, and TNF upon TBI, without significantly affecting the protein expression levels of inflammatory markers (RAGE, IL-6, IL-1β, and IL-10). At the early stage of TBI-induced inflammation, the gene expression of inflammatory mediators in both the lungs and liver is susceptible to ethanol-induced remote effects. Taken together, EI may alleviate the TBI-induced pro-inflammatory response in the trauma-distant organs, the lungs and liver, via the HMGB1-RAGE axis.

The Role of Acid Sphingomyelinase Inhibition in Repetitive Mild Traumatic Brain Injury

BACKGROUND

Chronic traumatic encephalopathy is a consequence of repetitive mild traumatic brain injury (rmTBI). These injuries can result in psychiatric disorders that are treated with amitriptyline. Amitriptyline improves neuronal regeneration in major depression via inhibition of acid sphingomyelinase. We hypothesized that acid sphingomyelinase inhibition would preserve neuronal regeneration and decrease depressive symptoms following rmTBI in a murine model.

METHODS

A murine model of rmTBI was established using a weight-drop method. Mice were subjected to mTBI every other day for 7 d. Mice received amitriptyline injection 2 h prior to each mTBI. After the final mTBI, mice underwent behavioral studies or biochemical analysis. Hippocampi were analyzed for markers of neurogenesis and phosphorylated tau aggregation.

RESULTS

Mice that underwent rmTBI showed increased hippocampal phosphorylated tau aggregation 1 mo following rmTBI as well as decreased neuronal regeneration by bromodeoxyuridine uptake and doublecortin immunohistochemistry. Mice with either genetic deficiency or pharmacologic inhibition of acid sphingomyelinase demonstrated improved neuronal regeneration and decreased phosphorylated tau aggregation compared to untreated rmTBI mice. Behavioral testing showed rmTBI mice spent significantly more time in the dark and waiting to initiate feeding compared to sham mice. These behaviors were partially prevented by the inhibition of acid sphingomyelinase.

CONCLUSIONS

We established a murine model of rmTBI that leads to tauopathy, depression, and impaired hippocampal neurogenesis. Inhibition of acid sphingomyelinase prevented the harmful neurologic and behavioral effects of rmTBI. These findings highlight an important opportunity to improve recovery or prevent neuropsychiatric decline in patients at risk for chronic traumatic encephalopathy.

Traumatic Brain Injury and Alcohol Drinking Alter Basolateral Amygdala Endocannabinoids in Female Rats

Traumatic brain injury (TBI) affects approximately 3 million Americans yearly and increases vulnerability to developing psychiatric comorbidities. Alcohol use disorder (AUD) is the most prevalent psychiatric diagnosis preceding injury and TBI may increase subsequent alcohol use. The basolateral amygdala (BLA) is a limbic structure commonly affected by TBI that is implicated in anxiety and AUD. Endocannabinoids (eCBs) regulate synaptic activity in the BLA, and BLA eCB modulation alters anxiety-like behavior and stress reactivity. Previous work from our laboratories showed that systemic eCB degradation inhibition ameliorates TBI-induced increases in anxiety-like behavior and motivation to respond for alcohol in male rats. Here, we used a lateral fluid percussion model to test moderate TBI effects on anxiety-like behavior, alcohol drinking, and eCB levels and cell signaling in BLA, as well as the effect of alcohol drinking on anxiety-like behavior and the BLA eCB system, in female rats. Our results show that TBI does not promote escalation of operant alcohol self-administration or increase anxiety-like behavior in female rats. In the BLA, TBI and alcohol drinking alter tissue amounts of 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide; AEA) 1 h post-injury, and 2-AG levels remain low 11 days post-injury. Eleven days after injury, BLA pyramidal neurons were hyperexcitable, but measures of synaptic transmission and eCB signaling were unchanged. These data show that TBI impacts BLA 2-AG tissue levels, that this effect is modified by alcohol drinking, and also that TBI increases BLA cell excitability.

Acid Sphingomyelinase Inhibition Mitigates Histopathological and Behavioral Changes in a Murine Model of Traumatic Brain Injury

Traumatic brain injury (TBI) can lead to the development of chronic traumatic encephalopathy as a result of neuronal phosphorylated tau (p-tau) protein aggregation and neuroinflammation. Acid sphingomyelinase (Asm) may also contribute to post-TBI neurodegenerative disorders. We hypothesized that Asm inhibition would ameliorate p-tau aggregation, neuroinflammation, and behavioral changes after TBI in a murine model. TBI was generated using a weight-drop method. Asm inhibition in wild-type mice was achieved with a single injection of amitriptyline 1 h after TBI. Genetic Asm ablation was achieved using Asm-deficient mice (Asm^-/-). Thirty days after TBI, mice underwent behavioral testing with the forced swim test for symptoms of depression or were euthanized for neurohistological analysis. Neuroinflammation was quantified using the microglial markers, ionized calcium-binding adaptor molecule 1 and transmembrane protein 119. Compared to sham mice, TBI mice demonstrated increased hippocampal p-tau. Mice that received amitriptyline after TBI demonstrated decreased p-tau compared to mice that received a saline control. Further, post-TBI Asm^-/- mice demonstrated lower levels of p-tau compared to wild-type mice. Though a decrease in neuroinflammation was observed at 1 month post-TBI, no change was demonstrated with mice treated with amitriptyline. Similarly, TBI mice were more likely to show depression compared to mice that received amitriptyline after TBI. Utilizing a weight-drop method to induce moderate TBI, we have shown that genetic deficiency or pharmacological inhibition of Asm prevented hippocampal p-tau aggregation 1 month after injury as well as decreased symptoms of depression. These findings highlight an opportunity to potentially reduce the long-term consequences of TBI.

Rapid alterations in neuroimmune gene expression after acute ethanol: Timecourse, sex differences and sensitivity to cranial surgery

Prior work has established that that an acute ethanol challenge mimicking high intensity alcohol consumption increased IL-6 and suppressed IL-1β and TNFα mRNA in intoxication, with the opposite pattern seen in withdrawal. These experiments utilized Sprague-Dawley rats to further extend these results across time course (from 45 min to 6 h after ethanol), sex, and central versus peripheral expression. Furthermore, these data show that cannulation surgery may selectively modify the central neuroimmune response to ethanol. These findings highlight a unique plasticity of IL-6 that is specific to central structures and responsive to alterations by environmental factors.

STAT6 mediates the effect of ethanol on neuroinflammatory response in TBI

Traumatic brain injury (TBI) and ethanol intoxication (EI) frequently coincide, particularly in young subjects. However, the mechanisms of their interaction remain poorly understood. Among other pathogenic pathways, TBI induces glial activation and neuroinflammation in the hippocampus, resulting in acute and chronic hippocampal dysfunction. In this regard, we investigated the role of EI affecting these responses unfolding after TBI. We used a blunt, weight-drop approach to model TBI in mice. Male mice were pre-administered with ethanol or vehicle to simulate EI. The neuroinflammatory response in the hippocampus was assessed by monitoring the expression levels of >20 cytokines, the phosphorylation status of transcription factors and the phenotype of microglia and astrocytes. We used AS1517499, a brain-permeable STAT6 inhibitor, to elucidate the role of this pathway in the EI/TBI interaction. We showed that TBI causes the elevation of IL-33, IL-1β, IL-38, TNF-α, IFN-α, IL-19 in the hippocampus at 3 h time point and concomitant EI results in the dose-dependent downregulation of IL-33, IL-1β, IL-38, TNF-α and IL-19 (but not of IFN-α) and in the selective upregulation of IL-13 and IL-12. EI is associated with the phosphorylation of STAT6 and the transcription of STAT6-controlled genes. Moreover, ethanol-induced STAT6 phosphorylation and transcriptional activation can be recapitulated in vitro by concomitant exposure of neurons to ethanol, depolarization and inflammatory stimuli (simulating the acute trauma). Acute STAT6 inhibition prevents the effects of EI on IL-33 and TNF-α, but not on IL-13 and negates acute EI beneficial effects on TBI-associated neurological impairment. Additionally, EI is associated with reduced microglial activation and astrogliosis as well as preserved synaptic density and baseline neuronal activity 7 days after TBI and all these effects are prevented by acute administration of the STAT6 inhibitor concomitant to EI. EI concomitant to TBI exerts significant immunomodulatory effects on cytokine induction and microglial activation, largely through the activation of STAT6 pathway, ultimately with beneficial outcomes.

When Two Wrongs Make a Right: The Effect of Acute and Chronic Binge Drinking on Traumatic Brain Injury Outcomes in Young Adult Female Rats

Alcohol is the most commonly abused drug by young adults across North America. Although alcohol consumption itself incurs a risk of neurological damage, it is also a significant risk factor for traumatic brain injury (TBI). TBI among young adults is described as a modern healthcare epidemic. The drastic changes occurring within their neurological networks put young adults at greater risk for developing long-term post-traumatic deficits. Contradictory findings have been indicated regarding the effects of alcohol consumption on TBI outcomes in adults, with some studies demonstrating detrimental effects, whereas others suggest neuroprotective abilities. However, little is known about the effects of alcohol consumption on TBI outcomes during the sensitive stage of early adulthood. Young adult female Sprague-Dawley rats were randomly assigned to one of six experimental conditions: Pre-injury alcohol+TBI; Pre-injury alcohol+Sham; Pre- and Post-injury alcohol+TBI; Pre- and Post-injury alcohol+Sham; No alcohol+TBI; No alcohol+Sham. Alcohol consumption groups received an amount of 10% v/v ethanol solution based on the animals' weight. Following the injury, the rats were subjected to a behavioral test battery to assess post-concussive symptomology. Overall, chronic binge drinking significantly improved TBI outcomes related to motor coordination and balance, whereas binge drinking in general significantly decreased anxiety-like behaviors. Additionally, in many cases, chronic binge drinking appears to return the TBI animal's behavioral outcomes to levels comparable to those of the no alcohol sham animals. Thus, the results suggest that alcohol may exhibit neuroprotective abilities in the context of early adulthood TBI.

Executive (dys)function after traumatic brain injury: special considerations for behavioral pharmacology

Executive function is an umbrella term that includes cognitive processes such as decision-making, impulse control, attention, behavioral flexibility, and working memory. Each of these processes depends largely upon monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in the frontal cortex, striatum, and hippocampus, among other brain areas. Traumatic brain injury (TBI) induces disruptions in monoaminergic signaling along several steps in the neurotransmission process - synthesis, distribution, and breakdown - and in turn, produces long-lasting deficits in several executive function domains. Understanding how TBI alters monoamingeric neurotransmission and executive function will advance basic knowledge of the underlying principles that govern executive function and potentially further treatment of cognitive deficits following such injury. In this review, we examine the influence of TBI on the following measures of executive function - impulsivity, behavioral flexibility, and working memory. We also describe monoaminergic-systems changes following TBI. Given that TBI patients experience alterations in monoaminergic signaling following injury, they may represent a unique population with regard to pharmacotherapy. We conclude this review by discussing some considerations for pharmacotherapy in the field of TBI.

Alcohol in Traumatic Brain Injury: Toxic or Therapeutic?

BACKGROUND

Alcohol (EtOH) poses a challenge in traumatic brain injuries (TBIs) given its metabolic and neurologic impact. Studies have had opposing results regarding mortality and complication rates in the intoxicated TBI patient. We hypothesized that trauma mechanism, brain injury severity, and blood alcohol concentration (BAC) would influence the impact of EtOH on mortality in TBI.

METHODS

We performed a single-institution retrospective review of consecutive adult trauma patients tested for EtOH and a diagnosis of TBI. The primary outcome was mortality, and secondary outcomes included infectious complications. The primary analysis included univariate and multivariate regression comparing mortality between intoxicated and sober patients, at different values of BAC, different brain injury severities, and among mechanisms of trauma.

RESULTS

Admission EtOH was assessed in 583 patients with TBI, with 256 testing positive for EtOH and 327 testing negative. Overall, EtOH was associated with lower mortality on univariate analysis (4.7% versus 8.9%, P = 0.05) but not on multivariate analysis (P = 0.21). There was no effect of EtOH on mortality when patients were stratified by brain injury severity or among penetrating trauma victims. However, EtOH was associated with lower overall infectious complications on univariate and multivariate regression. Finally, EtOH was predictive of mortality with an area under the receiver operator characteristic curve of 0.83.

CONCLUSIONS

We found that EtOH is not associated with mortality in the patient with TBI, suggesting no causative effect. However, EtOH showed some predictability of mortality based on a receiver operator characteristic analysis. Interestingly, EtOH was associated with lower infectious complications, suggesting an immunomodulatory effect of EtOH in TBI.

Assessment of Extracellular Cytokines in the Hippocampus of the Awake Behaving Rat Using Large-Molecule Microdialysis Combined with Multiplex Arrays After Acute and Chronic Ethanol Exposure

BACKGROUND

Studies have demonstrated persistent changes in central nervous system (CNS) cytokine gene expression following ethanol (EtOH) exposure. However, the low endogenous expression and short half-lives of cytokines in the CNS have made cytokine protein detection challenging. The goal of these studies was to establish parameters for use of large-molecule microdialysis and sensitive multiplexing technology for the simultaneous detection of brain cytokines, corticosterone (CORT), and EtOH concentrations in the awake behaving rat.

METHODS

Adult (P75+) male Sprague Dawley rats that were either naïve to EtOH (Experiment 1) or had a history of adolescent chronic intermittent EtOH (CIE; Experiment 2) were given an acute EtOH challenge during microdialysis. Experiment 1 examined brain EtOH concentrations, CORT and a panel of neuroimmune analytes, including cytokines associated with innate and adaptive immunity. The natural time course of changes in these cytokines was compared to the effects of an acute 1.5 or 3.0 g/kg intraperitoneal (i.p.) EtOH challenge. In Experiment 2, rats with a history of adolescent CIE or controls exposed to vehicle were challenged with 3.0 g/kg i.p. EtOH during microdialysis in adulthood, and a panel of cytokines was examined in parallel with brain EtOH concentrations and CORT.

RESULTS

The microdialysis procedure itself induced a cytokine-specific response that replicated across studies, specifically a sequential elevation of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-10. Surprisingly, acute EtOH did not significantly alter this course of cytokine fluctuations in the hippocampus. However, a history of adolescent CIE showed drastic effects on multiple neuroimmune analytes when rechallenged with EtOH as adults. Rats with a history of adolescent EtOH displayed a severely blunted neuroimmune response in adulthood, evinced by suppressed IL-1β, IL-10, and TNF-α.

CONCLUSIONS

Together, these findings provide a methodological framework for assessment of cytokine release patterns, their modulation by EtOH, and the long-lasting changes to neuroimmune reactivity evoked by a history of adolescent CIE.

Circulating Extracellular Vesicles and Their miR "Barcode" Differentiate Alcohol Drinkers With Liver Injury and Those Without Liver Injury in Severe Trauma Patients

Short Summary: Extracellular vesicles (EVs), released during tissue/cell injury, contain a “barcode” indicating specific microRNAs (miRs) that can uncover their origin. We examined whether systemic EVs possessing hepatic miR-signatures would indicate ongoing liver injury and clinical complications in trauma patients (TP). We grouped the patients of alcoholic drinkers into “alcohol-drinkers with liver injury (LI)” (EtOH with LI) or “alcohol-drinkers without LI” (EtOH w/o LI) and we compared these groups to “non-drinkers” (no EtOH). When we examined patient blood from the EtOH with LI group we found the total number of EVs to be increased, along with an increase in miR-122 and let7f—two EV-associated miRNAs—and several inflammation-associating cytokines, such as interleukin (IL)-6 and IL-33. In contrast, all of the aforementioned readouts were found to be decreased in the EtOH w/o LI group. These novel data demonstrate that hepatocyte damage in alcohol-intoxicated trauma patients presenting with liver injury can be reflected by an increase in circulating serum EVs, their specific miR-“barcode” and the concomitant increase of systemic inflammatory markers IL-6 and IL-33. Anti-inflammatory effect of alcohol-drinking in EtOH w/o LI can be presented by a reduced number of hepato-derived EVs, no upregulation of IL-6 and IL-33, and a miR “barcode” different from patients presenting with liver injury.

Background: Alcohol abuse is associated with (neuro)protective effects related to (head) injuries, and with negative effects regarding infection rates and survival in severely injured trauma patients (TP). Extracellular vesicles (EVs), which are released during tissue and/or cell injury, can contain a “barcode” including specific microRNAs (miRs) that uncover their origin. We examined whether EVs with a hepatic miR signature can be systemically measured, and whether they can indicate ongoing liver injury in alcohol-intoxicated TP and foretell clinical complications.

Patients/Methods: We enrolled 35 TP and measured blood EVs, IL-6, TNF-alpha, IL-1beta, IL-10 and IL-33, alcohol (ethanol, EtOH) concentration (BAC), GLDH, GGT, AST, ALT, leukocytes, platelets, and bilirubin. Within circulating EVs we measured the expression levels of miR-122, let7f, miR21, miR29a, miR-155, and miR-146a. Patients of alcohol-drinkers were grouped into “alcohol drinkers with liver injury (LI)” (EtOH with LI) or “alcohol drinkers without LI” (EtOH w/o LI) and compared to “non-drinkers” (no EtOH). We assessed systemic injury characteristics and the outcome of hospitalization with regard to sepsis, septic shock, pneumonia, or mortality.

Results: EtOH with LI patients had significantly increased rates of pneumonia vs. the EtOH w/o LI group. EVs, IL-6, and IL-33 levels were significantly increased in EtOH with LI vs. EtOH w/o LI group (p < 0.05). EV number correlated positively with ALT and IL-6 (p < 0.0001). Two miRs, miR-122 and let7f, were increased only in the blood EVs from the EtOH with LI group (p < 0.05). Five miRs, miR-122, let7f, miR-21, miR-29a, and miR-146a, were reduced in the blood EVs from the EtOH w/o LI group, vs. no EtOH (p < 0.05). Notably miR-122 correlated significantly with increased bilirubin levels in the EtOH with LI group (p < 0.05).

Conclusions: Liver injury in alcohol-intoxicated TP is reflected by increased EV numbers, their specific miR barcode, and the correlated increase of systemic inflammatory markers IL-6 and IL-33. Interestingly, severely injured TP without liver injury were found to have a reduced number of liver-derived EVs, no observed inflammatory infiltration and reduced specific miR “barcode.”

Variable saline resuscitation in a murine model of combined traumatic brain injury and haemorrhage

BACKGROUND

Resuscitation strategies for combined traumatic brain injury (TBI) with haemorrhage in austere environments are not fully established. Our aim was to establish the effects of various saline concentrations in a murine model of combined TBI and haemorrhage, and identify an effective resuscitative strategy for the far-forward environment.

METHODS

Male C57BL/6 mice underwent closed head injury and subjected to controlled haemorrhage to a systolic blood pressure of 25 mmHg via femoral artery cannulation for 60 min. Mice were resuscitated with a fixed volume bolus or variable volumes of fluid to achieve a systolic blood pressure goal of 80 mmHg with 0.9% saline, 3% saline, 0.1-mL bolus of 23.4% saline, or a 0.1-mL bolus of 23.4% saline followed by 0.9% saline (23.4+).

RESULTS

23.4% saline and 23.4+ resulted in higher mortality at 6 h compared to 0.9% saline. Use of 3% saline required less volume to achieve targeted resuscitation, did not affect survival, and did not exacerbate post-traumatic inflammation. While 23.4+ resuscitation utilized lower volume, it resulted in hypernatremia, azotemia, and elevated systemic pro-inflammatory cytokines. All groups except 3% saline demonstrated progression of neuron damage, with cerebral oedema highest with 0.9% saline.

CONCLUSIONS

3% saline demonstrated favourable balance of survival, blood pressure restoration, minimization of inflammation, and prevention of ongoing neurologic injury without contributing to significant physiologic derangements. 23.4% saline administration may not be appropriate in the setting of concomitant hypotension.

The Neuroprotective Effect of Ethanol Intoxication in Traumatic Brain Injury Is Associated with the Suppression of ErbB Signaling in Parvalbumin-Positive Interneurons

Ethanol intoxication (EI) is a frequent comorbidity of traumatic brain injury (TBI), but the impact of EI on TBI pathogenic cascades and prognosis is unclear. Although clinical evidence suggests that EI may have neuroprotective effects, experimental support is, to date, inconclusive. We aimed at elucidating the impact of EI on TBI-associated neurological deficits, signaling pathways, and pathogenic cascades in order to identify new modifiers of TBI pathophysiology. We have shown that ethanol administration (5 g/kg) before trauma enhances behavioral recovery in a weight-drop TBI model. Neuronal survival in the injured somatosensory cortex was also enhanced by EI. We have used phospho-receptor tyrosine kinase (RTK) arrays to screen the impact of ethanol on TBI-induced activation of RTK in somatosensory cortex, identifying ErbB2/ErbB3 among the RTKs activated by TBI and suppressed by ethanol. Phosphorylation of ErbB2/3/4 RTKs were upregulated in vGlut2⁺ excitatory synapses in the injured cortex, including excitatory synapses located on parvalbumin (PV)-positive interneurons. Administration of selective ErbB inhibitors was able to recapitulate, to a significant extent, the neuroprotective effects of ethanol both in sensorimotor performance and structural integrity. Further, suppression of PV interneurons in somatosensory cortex before TBI, by engineered receptors with orthogonal pharmacology, could mimic the beneficial effects of ErbB inhibitors. Thus, we have shown that EI interferes with TBI-induced pathogenic cascades at multiple levels, with one prominent pathway, involving ErbB-dependent modulation of PV interneurons.

Neuroprotective effect of acute ethanol intoxication in TBI is associated to the hierarchical modulation of early transcriptional responses

Ethanol intoxication is a risk factor for traumatic brain injury (TBI) but clinical evidence suggests that it may actually improve the prognosis of intoxicated TBI patients. We have employed a closed, weight-drop TBI model of different severity (2cm or 3cm falling height), preceded (-30min) or followed (+20min) by ethanol administration (5g/Kg). This protocol allows us to study the interaction of binge ethanol intoxication in TBI, monitoring behavioral changes, histological responses and the transcriptional regulation of a series of activity-regulated genes (immediate early genes, IEGs). We demonstrate that ethanol pretreatment before moderate TBI (2cm) significantly reduces neurological impairment and accelerates recovery. In addition, better preservation of neuronal numbers and cFos+cells was observed 7days after TBI. At transcriptional level, ethanol reduced the upregulation of a subset of IEGs encoding for transcription factors such as Atf3, c-Fos, FosB, Egr1, Egr3 and Npas4 but did not affect the upregulation of others (e.g. Gadd45b and Gadd45c). While a subset of IEGs encoding for effector proteins (such as Bdnf, InhbA and Dusp5) were downregulated by ethanol, others (such as Il-6) were unaffected. Notably, the majority of genes were sensitive to ethanol only when administered before TBI and not afterwards (the exceptions being c-Fos, Egr1 and Dusp5). Furthermore, while severe TBI (3cm) induced a qualitatively similar (but quantitatively larger) transcriptional response to moderate TBI, it was no longer sensitive to ethanol pretreatment. Thus, we have shown that a subset of the TBI-induced transcriptional responses were sensitive to ethanol intoxication at the instance of trauma (ultimately resulting in beneficial outcomes) and that the effect of ethanol was restricted to a certain time window (pre TBI treatment) and to TBI severity (moderate). This information could be critical for the translational value of ethanol in TBI and for the design of clinical studies aimed at disentangling the role of ethanol intoxication in TBI.

Neuroprotective effect of ethanol in acute carbon monoxide intoxication: A retrospective study

In acute carbon monoxide (CO) intoxication, treatment of neurologic injury and prevention of neurological sequelae are primary concerns. Ethanol is the one of the frequent substances which is co-ingested in intentional CO poisoning. Neuroprotective effect of ethanol was highlighted and demonstrated in isolated brain injury recently. We assessed the neuroprotective effect of ethanol in acute CO intoxication using magnetic resonance imaging (MRI).We retrospectively reviewed medical records for patients who visited an emergency medical center of a university-affiliated hospital during a period of 73 months, from March 2009 to April 2015. Enrolled patients were divided into 2 groups, patients with or without abnormal brain lesion in brain MRI. Multivariate logistic regression analysis was performed to assess the factors associated with brain injury in MRI.A total of 109 patients with acute CO intoxication were evaluated of which 66 (60.55%) tested positive in brain MRI. MRI lesion-positive patients were more likely to have electrocardiogram change, elevation of serum troponin I and s100 protein level and lower serum ethanol level. Serum ethanol positivity was an independent factor for prevalence of brain injury in MRI in acute CO poisoning.This study revealed that ethanol which is co-ingested in acute CO intoxication may work the neuroprotective effect and could consequence more favorable neurological outcome in acute CO intoxication.

Acute ethanol administration results in a protective cytokine and neuroinflammatory profile in traumatic brain injury

Ethanol intoxication is a common comorbidity in traumatic brain injury. To date, the effect of ethanol on TBI pathogenic cascades and resulting outcomes remains debated. A closed blunt weight-drop murine TBI model has been implemented to investigate behavioral (by sensorimotor and neurological tests), and neuro-immunological (by tissue cytokine arrays and immuno-histology) effects of ethanol intoxication on TBI. The effect of the occurrence of traumatic intracerebral hemorrhage was also studied. The results indicate that ethanol pretreatment results in a faster and better recovery after TBI with reduced infiltration of leukocytes and reduced microglia activation. These outcomes correspond to reduced parenchymal levels of GM-CSF, IL-6 and IL-3 and to the transient upregulation of IL-13 and VEGF, indicating an early shift in the cytokine profile towards reduced inflammation. A significant difference in the cytokine profile was still observed 24h post injury in the ethanol pretreated mice, as shown by the delayed peak in IL-6 and by the suppression of GM-CSF, IFN-γ, and IL-3. Seven days post-injury, ethanol-pretreated mice displayed a significant decrease both in CD45+ cells infiltration and in microglial activation. On the other hand, in the case of traumatic intracerebral hemorrhage, the cytokine profile was dominated by KC, CCL5, M-CSF and several interleukins and ethanol pretreatment did not produce any modification. We can thus conclude that ethanol intoxication suppresses the acute neuro-inflammatory response to TBI, an effect which is correlated with a faster and complete neurological recovery, whereas, the presence of traumatic intracerebral hemorrhage overrides the effects of ethanol.

Emergency department blood alcohol level associates with injury factors and six-month outcome after uncomplicated mild traumatic brain injury

The relationship between blood alcohol level (BAL) and mild traumatic brain injury (mTBI) remains in need of improved characterization. Adult patients suffering mTBI without intracranial pathology on computed tomography (CT) from the prospective Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot study with emergency department (ED) Glasgow Coma Scale (GCS) 13-15 and recorded blood alcohol level (BAL) were extracted. BAL≥80-mg/dl was set as proxy for excessive use. Multivariable regression was performed for patients with six-month Glasgow Outcome Scale-Extended (GOSE; functional recovery) and Wechsler Adult Intelligence Scale Processing Speed Index Composite Score (WAIS-PSI; nonverbal processing speed), using BAL≥80-mg/dl and <80-mg/dl cohorts, adjusting for demographic/injury factors. Overall, 107 patients were aged 42.7±16.8-years, 67.3%-male, and 80.4%-Caucasian; 65.4% had BAL=0-mg/dl, 4.6% BAL<80-mg/dl, and 30.0% BAL≥80-mg/dl (range 100-440-mg/dl). BAL differed across loss of consciousness (LOC; none: median 0-mg/dl [interquartile range (IQR) 0-0], <30-min: 0-mg/dl [0-43], ≥30-min: 224-mg/dl [50-269], unknown: 108-mg/dl [0-232]; p=0.002). GCS<15 associated with higher BAL (19-mg/dl [0-204] vs. 0-mg/dl [0-20]; p=0.013). On univariate analysis, BAL≥80-mg/dl associated with less-than-full functional recovery (GOSE≤7; 38.1% vs. 11.5%; p=0.025) and lower WAIS-PSI (92.4±12.7, 30th-percentile vs. 105.1±11.7, 63rd-percentile; p<0.001). On multivariable regression BAL≥80-mg/dl demonstrated an odds ratio of 8.05 (95% CI [1.35-47.92]; p=0.022) for GOSE≤7 and an adjusted mean decrease of 8.88-points (95% CI [0.67-17.09]; p=0.035) on WAIS-PSI. Day-of-injury BAL>80-mg/dl after uncomplicated mTBI was associated with decreased GCS score and prolongation of reported LOC. BAL may be a biomarker for impaired return to baseline function and decreased nonverbal processing speed at six-months postinjury. Future confirmatory studies are needed.

Mortality-Associated Characteristics of Patients with Traumatic Brain Injury at the University Teaching Hospital of Kigali, Rwanda

OBJECTIVE

Traumatic brain injury (TBI) is a leading cause of death and disability. Patients with TBI in low and middle-income countries have worse outcomes than patients in high-income countries. We evaluated important clinical indicators associated with mortality for patients with TBI at University Teaching Hospital of Kigali, Kigali, Rwanda.

METHODS

A prospective consecutive sampling of patients with TBI presenting to University Teaching Hospital of Kigali Accident and Emergency Department was screened for inclusion criteria: reported head trauma, alteration in consciousness, headache, and visible head trauma. Exclusion criteria were age <10 years, >48 hours after injury, and repeat visit. Data were assessed for association with death using logistic regression. Significant variables were included in a multivariate logistic regression model and refined via backward elimination.

RESULTS

Between October 7, 2013, and April 6, 2014, 684 patients were enrolled; 14 (2%) were excluded because of incomplete data. Of patients, 81% were male with mean age of 31 years (range, 10-89 years; SD 11.8). Most patients (80%) had mild TBI (Glasgow Coma Scale [GCS] score 13-15); 10% had moderate (GCS score 9-12) and 10% had severe (GCS score 3-8) TBI. Multivariate logistic regression determined that GCS score <13, hypoxia, bradycardia, tachycardia, and age >50 years were significantly associated with death.

CONCLUSIONS

GCS score <13, hypoxia, bradycardia, tachycardia, and age >50 years were associated with mortality. These findings inform future research that may guide clinicians in prioritizing care for patients at highest risk of mortality.

Hemotransfusion and mechanical ventilation time are associated with intra-hospital mortality in patients with traumatic brain injury admitted to intensive care unit

OBJECTIVE

To identify the factors associated with the intra-hospital mortality in patients with traumatic brain injury (TBI) admitted to intensive care unit (ICU).

METHODS

The sample included patients with TBI admitted to the ICU consecutively in a period of one year. It was defined as variables the epidemiological characteristics, factors associated with trauma and variables arising from clinical management in the ICU.

RESULTS

The sample included 87 TBI patients with a mean age of 28.93 ± 12.72 years, predominantly male (88.5%). The intra-hospital mortality rate was of 33.33%. The initial univariate analysis showed a significant correlation of intra-hospital death and the following variables: the reported use of alcohol (p = 0.016), hemotransfusion during hospitalization (p = 0.036), and mechanical ventilation time (p = 0.002).

CONCLUSION

After multivariate analysis, the factors associated with intra-hospital mortality in TBI patients admitted to the intensive care unit were the administration of hemocomponents and mechanical ventilation time.

Traumatic brain injury and alcohol/substance abuse: A Bayesian meta-analysis comparing the outcomes of people with and without a history of abuse

Alcohol and substance (drugs and/or alcohol) abuse are major risk factors for traumatic brain injury (TBI); however, it remains unclear whether outcomes differ for those with and without a history of preinjury abuse. A meta-analysis was performed to examine this issue. The PubMed, Embase, and PsycINFO databases were searched for research that compared the neuroradiological, cognitive, or psychological outcomes of adults with and without a documented history of alcohol and/or substance abuse who sustained nonpenetrating TBIs. Data from 22 studies were analyzed using a random-effects model: Hedges's g effect sizes measured the mean difference in outcomes of individuals with/without a history of preinjury abuse, and Bayes factors assessed the probability that the outcomes differed. Patients with a history of alcohol and/or substance abuse had poorer neuroradiological outcomes, including reduced hippocampal (g = -0.82) and gray matter volumes (g = -0.46 to -0.82), and enlarged cerebral ventricles (g = -0.73 to -0.80). There were limited differences in cognitive outcomes: Executive functioning (g = -0.51) and memory (g = -0.39 to -0.43) were moderately affected, but attention and reasoning were not. The findings for fine motor ability, construction, perception, general cognition, and language were inconclusive. Postinjury substance and alcohol use (g = -0.97 to -1.07) and emotional functioning (g = -0.29 to -0.44) were worse in those with a history of alcohol and/or substance abuse (psychological outcomes). This study highlighted the type and extent of post-TBI differences between persons with and without a history of alcohol or substance abuse, many of which may hamper recovery. However, variation in the criteria for premorbid abuse, limited information regarding the history of abuse, and an absence of preinjury baseline data prevented an assessment of whether the differences predated the TBI, occurred as a result of ongoing alcohol/substance abuse, or reflected the cumulative impact of alcohol/substance abuse and TBI.

Impact of day-of-injury alcohol consumption on outcomes after traumatic brain injury: A meta-analysis

Although a known risk factor for traumatic brain injury (TBI), alcohol has been found to both promote and protect against secondary brain damage. However, it is presently unclear whether the cognitive, psychological and medical/functional outcomes of adults who have consumed alcohol prior to sustaining a TBI differ from those who have not. This meta-analysis examined the outcomes of groups that differed in terms of their day-of-injury (DOI) blood alcohol levels (BALs) by comparing positive with zero BAL (BAL⁺/BAL^-) and high with low BAL (BAL^high/BAL^low) samples. The PubMed, PsycINFO, EMBASE, and Scopus databases were searched from inception until the end of March 2015. Hedge's g effects (continuous data) and odds ratios (categorical data) were calculated for 27 studies that compared either the outcomes of BAL⁺ and BAL^- groups or BAL^high and BAL^low groups. BAL⁺ was associated with significantly poorer cognitive outcomes (overall and on general tests) and higher levels of disability, and BAL^high was associated with shorter stays in intensive care. More generally, however, most effect sizes were small to low-moderate in size, non-significant and inconsistent in their direction. Although DOI alcohol consumption increases the risk of sustaining a TBI, it is not consistently associated with better or worse outcomes, other than subtle cognitive deficits; the source of which remains to be determined.

Effects of positive blood alcohol concentration on outcome and systemic interleukin-6 in major trauma patients

BACKGROUND

The influence of alcohol on the outcome after major trauma remains controversial. In several recent studies, alcohol has been associated with neuroprotective effects in head injuries, while others reported negative or no effects on survival and/or the in-hospital stay in major trauma patients (TP). The purpose of this study was to examine the relationship of alcohol with injury characteristics and outcome as well as to analyze possible anti-inflammatory properties in major TP.

PATIENTS/METHODS

184 severely injured TP with an Injury Severity Score (ISS) ≥16 were successively enrolled. All patients had measured blood alcohol concentration (BAC). Patients were grouped according to their positive BAC (>0.5‰, BAC) vs. <0.5‰ alcohol (no BAC) upon arrival at the emergency department (ED). Injury characteristics, physiologic parameters and outcome with respect to organ or multiple organ failure (MOF), SIRS, sepsis, pneumonia, ARDS or mortality were assessed. Systemic levels of interleukin (IL)-6 at ED were determined.

RESULTS

Forty-nine TP had positive BAC without chronic alcohol abuse history and 135 patients had BAC levels below 0.5‰. Overall injury severity and age were comparable in both groups. No BAC TP received significantly higher numbers of packed red blood cells and fresh frozen plasma (transfused within the initial 24h or in total) compared to BAC TP. Organ failure, MOF, SIRS, sepsis, pneumonia, ARDS and the in-hospital mortality were not different between both groups. Trauma patients with positive BAC had significantly decreased leukocyte numbers and systemic IL-6 levels compared to no BAC group. There was a significant positive correlation between leukocyte counts and IL-6 as well as BAC and leukocytes. BAC levels did not correlate with IL-6.

CONCLUSIONS

Positive BAC is associated with reduced leukocyte numbers and lowered systemic IL-6 levels at admittance indicating immune-suppressive effects of alcohol in major trauma patients.

Neuroprotection for traumatic brain injury

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Despite extensive preclinical research supporting the effectiveness of neuroprotective therapies for brain trauma, there have been no successful randomized controlled clinical trials to date. TBI results in delayed secondary tissue injury due to neurochemical, metabolic and cellular changes; modulating such effects has provided the basis for neuroprotective interventions. To establish more effective neuroprotective treatments for TBI it is essential to better understand the complex cellular and molecular events that contribute to secondary injury. Here we critically review relevant research related to causes and modulation of delayed tissue damage, with particular emphasis on cell death mechanisms and post-traumatic neuroinflammation. We discuss the concept of utilizing multipotential drugs that target multiple secondary injury pathways, rather than more specific "laser"-targeted strategies that have uniformly failed in clinical trials. Moreover, we assess data supporting use of neuroprotective drugs that are currently being evaluated in human clinical trials for TBI, as well as promising emerging experimental multipotential drug treatment strategies. Finally, we describe key challenges and provide suggestions to improve the likelihood of successful clinical translation.

Alcohol's Burden on Immunity Following Burn, Hemorrhagic Shock, or Traumatic Brain Injury

Alcohol consumption contributes to increased incidence and severity of traumatic injury. Compared with patients who do not consume alcohol, alcohol-consuming patients have higher rates of long-term morbidity and mortality during recovery from injury. This can be attributed in part to an impaired immune response in individuals who consume alcohol. Acute and chronic alcohol use can affect both the innate and adaptive immune defense responses within multiple organ systems; the combination of alcohol use and injury results in increased susceptibility to bacterial and viral pathogens. This review examines the major deleterious effects of alcohol on immunity following tissue damage or traumatic injury, with a focus on alcohol's influence on the ability of the immune and major organ systems to fight disease and to repair damaged tissues following injury.

Prevalence and consequences of positive blood alcohol levels among patients injured at work

Aims:

The aim of this study was to characterize positive blood alcohol among patients injured at work, and to compare the severity of injury and outcome of blood alcohol concentration (BAC) positive and negative patients.

Settings and Design:

A retrospective cohort study was performed at a Level 1 academic trauma center. Patients injured at work between 01/01/07 and 01/01/12 and admitted with positive (BAC+) vs negative (BAC−) blood alcohol were compared using bivariate analysis.

Results:

Out of 823, 319 subjects were tested for BAC (38.8%), of whom 37 were BAC+ (mean 0.151 g/dL, range 0.015-0.371 g/dL). Age (41 years), sex (97.2% men), race, intensive care unit (ICU) and hospital length of stay (LOS), and mortality were similar between groups. Nearly half of BAC+ cases were farming injuries (18, 48.6%): Eight involved livestock, five involved all-terrain vehicles (ATVs), three involved heavy equipment, one fell, and one had a firearm injury. Eight (21.6%) were construction site injuries involving falls from a roof or scaffolding, five (13.5%) were semi-truck collisions, four (10.8%) involved falls from a vehicle in various settings, and two (5.4%) were crush injuries at an oilfield. BAC+ subjects were less likely to be injured in construction sites and oilfields, including vehicle-related falls (2.3 vs 33.9%, P < 0.0001). Over half of BAC+ (n = 20, 54%) subjects were alcohol dependent; three (8.1%) also tested positive for cocaine on admission. No BAC+ subjects were admitted to rehabilitation compared to 33 (11.7%) of BAC− subjects. Workers’ compensation covered a significantly smaller proportion of BAC+ patients (16.2 vs 61.0%, P < 0.0001).

Conclusions:

Alcohol use in the workplace is more prevalent than commonly suspected, especially in farming and other less regulated industries. BAC+ is associated with less insurance coverage, which probably affects resources available for post-discharge rehabilitation and hospital reimbursement.

Microglial AGE-albumin is critical in promoting alcohol-induced neurodegeneration in rats and humans

Alcohol is a neurotoxic agent, since long-term heavy ingestion of alcohol can cause various neural diseases including fetal alcohol syndrome, cerebellar degeneracy and alcoholic dementia. However, the molecular mechanisms of alcohol-induced neurotoxicity are still poorly understood despite numerous studies. Thus, we hypothesized that activated microglial cells with elevated AGE-albumin levels play an important role in promoting alcohol-induced neurodegeneration. Our results revealed that microglial activation and neuronal damage were found in the hippocampus and entorhinal cortex following alcohol treatment in a rat model. Increased AGE-albumin synthesis and secretion were also observed in activated microglial cells after alcohol exposure. The expressed levels of receptor for AGE (RAGE)-positive neurons and RAGE-dependent neuronal death were markedly elevated by AGE-albumin through the mitogen activated protein kinase pathway. Treatment with soluble RAGE or AGE inhibitors significantly diminished neuronal damage in the animal model. Furthermore, the levels of activated microglial cells, AGE-albumin and neuronal loss were significantly elevated in human brains from alcoholic indivisuals compared to normal controls. Taken together, our data suggest that increased AGE-albumin from activated microglial cells induces neuronal death, and that efficient regulation of its synthesis and secretion is a therapeutic target for preventing alcohol-induced neurodegeneration.

Effect of alcohol in traumatic brain injury: is it really protective?

BACKGROUND

Studies have proposed a neuroprotective role for alcohol (ETOH) in traumatic brain injury (TBI). We hypothesized that ETOH intoxication is associated with mortality in patients with severe TBI.

METHODS

Version 7.2 of the National Trauma Data Bank (2007-2010) was queried for all patients with isolated blunt severe TBI (Head Abbreviated Injury Score ≥4) and blood ETOH levels recorded on admission. Primary outcome measure was mortality. Multivariate logistic regression analysis was performed to assess factors predicting mortality and in-hospital complications.

RESULTS

A total of 23,983 patients with severe TBI were evaluated of which 22.8% (n = 5461) patients tested positive for ETOH intoxication. ETOH-positive patients were more likely to have in-hospital complications (P = 0.001) and have a higher mortality rate (P = 0.01). ETOH intoxication was an independent predictor for mortality (odds ratio: 1.2, 95% confidence interval: 1.1-2.1, P = 0.01) and development of in-hospital complications (odds ratio: 1.3, 95% confidence interval: 1.1-2.8, P = 0.009) in patients with isolated severe TBI.

CONCLUSIONS

ETOH intoxication is an independent predictor for mortality in patients with severe TBI patients and is associated with higher complication rates. Our results from the National Trauma Data Standards differ from those previously reported. The proposed neuroprotective role of ETOH needs further clarification.

Effects of time of hospital admission on outcomes after severe traumatic brain injury in Austria

BACKGROUND

The goal of this study was to compare outcomes of patients with severe traumatic brain injury (TBI) who had been admitted either during workdays from 7 a.m. to 7 p.m. ("regular service") or during any other time ("on-call service").

MATERIAL AND METHODS

Between March 2002 and April 2012, 17 Austrian centers enrolled TBI patients into two observational studies that focused on effects of guideline compliance (n = 400) and on prehospital and early hospital management (n = 777), respectively. Data on trauma severity, clinical status, treatment, and outcomes were collected prospectively. All patients with severe TBI (Glasgow Coma Scale score < 9) were selected for this analysis. Secondary transfers and patients with unsurvivable injuries were excluded. The International Mission for Prognosis and Analysis of Clinical Trials in TBI core model was used to estimate probabilities of hospital death and unfavorable long-term outcome (Glasgow Outcome Scale score < 4). Based on time of arrival, patients were assigned to groups "regular service" or "on-call service."

RESULTS

Data from 852 patients were analyzed (413 "regular," 439 "on-call service"). "On-call" patients were younger (45 vs. 51 years, P < 0.001) and had a higher rate of alcohol intoxication (41 vs. 11 %, P < 0.001). Trauma severity was comparable; the probabilities of death and unfavorable outcome were identical. There were no differences regarding computed tomography findings or treatment. Hospital mortality (24 vs. 28 %, P = 0.191) and rate of patients with unfavorable outcome at 6 months (43 vs. 48 %, P = 0.143) were comparable.

CONCLUSIONS

In Austria, the time of hospital admission has no influence on outcomes after severe TBI.

Acute alcohol intoxication prolongs neuroinflammation without exacerbating neurobehavioral dysfunction following mild traumatic brain injury

Traumatic brain injury (TBI) represents a leading cause of death and disability among young persons with ∼1.7 million reported cases in the United States annually. Although acute alcohol intoxication (AAI) is frequently present at the time of TBI, conflicting animal and clinical reports have failed to establish whether AAI significantly impacts short-term outcomes after TBI. The objective of this study was to determine whether AAI at the time of TBI aggravates neurobehavioral outcomes and neuroinflammatory sequelae post-TBI. Adult male Sprague-Dawley rats were surgically instrumented with gastric and vascular catheters before a left lateral craniotomy. After recovery, rats received either a primed constant intragastric alcohol infusion (2.5 g/kg+0.3 g/kg/h for 15 h) or isocaloric/isovolumic dextrose infusion followed by a lateral fluid percussion TBI (∼1.4 J, ∼30 ms). TBI induced apnea and a delay in righting reflex. AAI at the time of injury increased the TBI induced delay in righting reflex without altering apnea duration. Neurological and behavioral dysfunction was observed at 6 h and 24 h post-TBI, and this was not exacerbated by AAI. TBI induced a transient upregulation of cortical interleukin (IL)-6 and monocyte chemotactic protein (MCP)-1 mRNA expression at 6 h, which was resolved at 24 h. AAI did not modulate the inflammatory response at 6 h but prevented resolution of inflammation (IL-1, IL-6, tumor necrosis factor-α, and MCP-1 expression) at 24 h post-TBI. AAI at the time of TBI did not delay the recovery of neurological and neurobehavioral function but prevented the resolution of neuroinflammation post-TBI.