Quetiapine protects the blood-brain barrier in traumatic brain injury

Sonic Hedgehog reduces inflammatory response, decreases blood-spinal cord barrier permeability, and improves locomotor function recovery in an acute spinal cord injury rat model

BACKGROUND

Sonic Hedgehog (Shh), extensively researched for its role in early neurogenesis and brain development, has recently been recognized for its neuroprotective potential following neuronal injuries. This study examines the immediate impact of early administered Shh on the local inflammatory response post-acute spinal cord injury in rats.

METHODS

Thirty-four female Wistar rats underwent either sham surgery (laminectomy; n = 10) or clip compression/contusion spinal cord injury (SCI) at the T9 level. This was followed by implantation of an osmotic pump and a subdural catheter for continuous intrathecal delivery of Shh (n = 12) or placebo (NaCl; n = 12). Locomotor function was assessed at 3- and 7-days post-injury (dpi) using the Basso, Beattie, and Bresnahan (BBB) score and the Gridwalk test. Animals were euthanized after 3 or 7 days for immunohistochemical analysis of the local inflammatory reaction and immune cell migration.

RESULTS

Shh-treated rats demonstrated significant hindlimb movement and coordination improvements at 7 days post-injury, compared to controls. This enhancement was accompanied by a significant reduction in both immune cell presence and blood plasma products within spinal cord lesions, suggesting Shh's dual role in modulating immune cell migration and maintaining the integrity of the blood-spinal cord barrier. Separately, these Shh-treated rats also showed an increase in M(IL-4) polarization of macrophages, further underlining the potential therapeutic impact of Shh in post-injury recovery. Notably, these effects were not evident at three days post-injury.

CONCLUSION

Shh application at 7 days post-injury showed immunomodulatory effects, possibly via enhanced blood-spinal cord barrier integrity, reduced immune cell migration, and increased anti-inflammatory immune cell differentiation. These mechanisms collectively contribute to enhanced locomotor recovery.

Impact of quetiapine on ion channels and contractile dynamics in rat ventricular myocyte

Antipsychotic drugs often lead to adverse effects, including those related to the cardiovascular system. Of these, quetiapine is known to cause significant changes in the QT interval although the underlying mechanism remains mysterious, prompting us to examine its effects on cardiac electrophysiological properties. Therefore, we investigated the effect of quetiapine on contraction, action potential (AP), and the associated membrane currents such as L-type Ca2+ and K+ using the whole-cell patch clamp method to examine its impacts on isolated rat ventricular myocytes. Our results showed that (1) quetiapine reduces cell contractility in a concentration-dependent manner and (2) leads to a significant prolongation in the duration of AP in isolated ventricular myocytes. This effect was both concentration and frequency-dependent; (3) quetiapine significantly decreased the Ca2+, transient outward K+, and steady-state K+ currents. However, only high concentration of quetiapine (100 μM) could significantly change the activation and reactivation kinetics of L-type Ca2+ channels. This study demonstrates that QT extension induced by quetiapine is mainly associated with the prolongation of AP. Moreover, quetiapine caused a significant decrease in contractile force and excitability of ventricular myocytes by suppressing Ca2+ and K+ currents.

Matrix Metalloproteinase-9 inhibitors as therapeutic drugs for traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality among young adults and the elderly. In the United States, TBI is responsible for around 30 percent of all injuries brought on by injuries in general. Vasogenic cerebral edema due to blood-brain barrier (BBB) dysfunction and the associated elevation of intracranial pressure (ICP) are some of the major causes of secondary injuries following traumatic brain injury. Matrix metalloproteinase-9 (MMP-9) is a therapeutic target for being an enzyme that degrades the proteins that make up a part of the microvascular basal lamina as well as inter-endothelial tight junctions of the blood-brain barrier. MMP-9-mediated BBB dysfunctions and the compromise of the BBB is a major pathway that leads the development of vasogenic cerebral edema, elevation of ICP, poor cerebral perfusion and brain herniation following traumatic brain injury. That makes MMP-9 an effective therapeutic target and endogenous or exogenous MMP-9 inhibitors as therapeutic drugs for preventing secondary brain damage after traumatic brain injury. Although our understanding of the mechanisms that underlie the primary and secondary stages of damage following a TBI has significantly improved in recent years, such information has not yet resulted in the successful development of novel pharmacological treatment options for traumatic brain injury. Recent pre-clinical and/or clinical studies have demonstrated that there are several compounds with specific or non-specific MMP-9 inhibitory properties either directly binding and inhibiting MMP-9 or by indirectly inhibiting MMP-9, with potential as therapeutic agents for traumatic brain injury. This article reviews the efficacy of several such medications and potential agents that include endogenous and exogeneous compounds that are at various levels of research and development. MMP-9-based therapeutic drug development has enormous potential in the pharmacological treatment of cerebral edema and/or neuronal injury resulting from traumatic brain injury.

Selective sphingosine-1-phosphate receptor 1 modulator attenuates blood-brain barrier disruption following traumatic brain injury by inhibiting vesicular transcytosis

BACKGROUND

Traumatic brain injury (TBI) provokes secondary pathological damage, such as damage to the blood-brain barrier (BBB), ischaemia and inflammation. Major facilitator superfamily domain-containing 2a (Mfsd2a) has been demonstrated to be critical in limiting the increase in BBB vesicle transcytosis following brain injury. Recent studies suggest that a novel and selective modulator of the sphingosine-1-phosphate receptor 1 (S1P1), CYM-5442, maintains the integrity of the BBB by restricting vesicle transcytosis during acute ischaemic stroke. In the current study, we investigated whether CYM-5442, evaluated in a short-term study, could protect the brains of mice with acute-stage TBI by reversing the increase in vesicle transport due to reduced Mfsd2a expression after TBI.

METHODS

We used the well-characterized model of TBI caused by controlled cortical impact. CYM-5442 (0.3, 1, 3 mg/kg) was intraperitoneally injected 30 min after surgery for 7 consecutive days. To investigate the effect of CYM-5442 on vesicle transcytosis, we downregulated and upregulated Mfsd2a expression using a specific AAV prior to evaluation of the TBI model. MRI scanning, cerebral blood flow, circulating blood counts, ELISA, TEM, WB, and immunostaining evaluations were performed after brain injury.

RESULTS

CYM-5442 significantly attenuated neurological deficits and reduced brain oedema in TBI mice. CYM-5442 transiently suppressed lymphocyte trafficking but did not induce persistent lymphocytopenia. After TBI, the levels of Mfsd2a were decreased significantly, while the levels of CAV-1 and albumin were increased. In addition, Mfsd2a deficiency caused inadequate sphingosine-1-phosphate (S1P) transport in the brain parenchyma, and the regulation of BBB permeability by Mfsd2a after TBI was shown to be related to changes in vesicle transcytosis. Downregulation of Mfsd2a in mice markedly increased the BBB permeability, neurological deficit scores, and brain water contents after TBI. Intervention with CYM-5442 after TBI protected the BBB by significantly reducing the vesicle transcytosis of cerebrovascular endothelial cells.

CONCLUSION

In addition to transiently suppressing lymphocytes, CYM-5442 alleviated the neurological deficits, cerebral edema and protective BBB permeability in TBI mice by reducing the vesicle transcytosis of cerebrovascular endothelial cells.

Blood-brain barrier dysfunction in bipolar disorder: Molecular mechanisms and clinical implications

Bipolar disorder (BD) is a severe psychiatric disorder affecting approximately 1-3% of the population and characterized by a chronic and recurrent course of debilitating symptoms. An increasing focus has been directed to discover and explain the function of Blood-Brain Barrier (BBB) integrity and its association with a number of psychiatric disorders; however, there has been limited research in the role of BBB integrity in BD. Multiple pathways may play crucial roles in modulating BBB integrity in BD, such as inflammation, insulin resistance, and alterations of neuronal plasticity. In turn, BBB impairment is hypothesized to have a significant clinical impact in BD patients. Based on the high prevalence of medical and psychiatric comorbidities in BD and a growing body of evidence linking inflammatory and neuroinflammatory mechanisms to the disorder, recent studies have suggested that BBB dysfunction may play a key role in BD's pathophysiology. In this comprehensive narrative review, we aim to discuss studies investigating biological markers of BBB in patients with BD, mechanisms that modulate BBB integrity, their clinical implications on patients, and key targets for future development of novel therapies.

Pre-existing psychiatric disorder is related to lower mortality from road traffic accident: A Japanese nationwide retrospective cohort study

BACKGROUND

Previous studies have reported inconsistent results on the mortality from trauma among psychiatric patients comparing to non-psychiatric population, which may be partly explained by the inclusion of both suicidal and accidental trauma. This study aimed to investigate the association of psychiatric diagnoses on admission with the outcomes of hospitalized patients for accidental trauma, namely road traffic injury.

METHODS

Detailed information of patients aged 15 years or older who were hospitalized for road traffic injury between 2004 and 2017 was extracted from the Japan Trauma Data Bank. The primary outcome was to compare in-hospital mortality between patients with and without a psychiatric disorder. We also conducted a subgroup analysis among patients with and without a serious head injury.

RESULTS

Altogether, 85,069 patients were included. Of these, 3,895 patients (4.6%) had a psychiatric diagnosis. The in-hospital mortality rate was significantly lower among patients with a psychiatric diagnosis than those without (5.4% vs. 8.3%; adjusted odds ratio [OR] 0.57, 95% confidence interval [CI] 0.47-0.70, p<0.001). In a subgroup analysis of patients with a serious head injury, in-hospital mortality was significantly lower in patients with a psychiatric diagnosis than in those without (10.5% vs. 17.3%; adjusted OR 0.48, 95% CI 0.37-0.62, p<0.001); in-hospital mortality of patients without a serious head injury showed no differences between patients with or without a psychiatric diagnosis (2.8% vs. 3.5%; adjusted OR 0.84, 95% CI 0.61-1.16, p=0.295).

CONCLUSIONS

In-hospital mortality from road traffic injury was significantly lower among patients with a psychiatric diagnosis than those without, which was primarily evident in a subgroup of patients with a serious head injury. While further replication is necessary, results might be indicative of the neuroprotective effect of psychotropic medications.

Ulinastatin alleviates traumatic brain injury by reducing endothelin-1

Background

Brain edema is one of the major causes of fatality and disability associated with injury and neurosurgical procedures. The goal of this study was to evaluate the effect of ulinastatin (UTI), a protease inhibitor, on astrocytes in a rat model of traumatic brain injury (TBI).

Methodology

A rat model of TBI was established. Animals were randomly divided into 2 groups – one group was treated with normal saline and the second group was treated with UTI (50,000 U/kg). The brain water content and permeability of the blood–brain barrier were assessed in the two groups along with a sham group (no TBI). Expression of the glial fibrillary acidic protein, endthelin-1 (ET-1), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) were measured by immunohistochemistry and western blot. Effect of UTI on ERK and PI3K/AKT signaling pathways was measured by western blot.

Results

UTI significantly decreased the brain water content and extravasation of the Evans blue dye. This attenuation was associated with decreased activation of the astrocytes and ET-1. UTI treatment decreased ERK and Akt activation and inhibited the expression of pro-inflammatory VEGF and MMP-9.

Conclusion

UTI can alleviate brain edema resulting from TBI by inhibiting astrocyte activation and ET-1 production.

The neuroprotective effect of quetiapine in critically ill traumatic brain injury patients

INTRODUCTION

Quetiapine is an atypical antipsychotic commonly used in critical care. Cellular and animal models demonstrated its novel anti-inflammatory properties in traumatic brain injury (TBI). Our study aimed to assess the effect of quetiapine on outcomes in critically ill TBI patients. We hypothesize that quetiapine improves neurological outcomes.

METHODS

The Multiparameter Intelligent Monitoring in Intensive Care database was queried, and all adult (age, ≥18 years) isolated TBI patients (extracranial Abbreviated Injury Scale, < 2) admitted to the intensive care unit for a period of >48 hours. Patients were stratified into quetiapine (+) and no-quetiapine (-) groups. Propensity score matching was performed (1:2 ratio). Outcome measures were intensive care unit length of stay, discharge Glasgow Coma Scale (GCS), and mortality. A subanalysis was performed for patients who underwent intracranial pressure (ICP) monitoring to ascertain the effect of quetiapine dose on ICP, and cerebral perfusion pressure (CPP). Survival curves and regression analyses were performed.

RESULTS

A matched cohort of (quetiapine, 116 vs. no-quetiapine, 232) patients was obtained. Mean ± SD age was 65 ± 21 years, median head Abbreviated Injury Scale was 3 (3-4), and median GCS was 10 (9-16). The median quetiapine dose given was 50 (25-125) mg. Patients who received quetiapine had lower mortality (17.2% vs. 27.6%; p = 0.03) and a higher median GCS at discharge (12 [11-14] vs. 11 [10-13]; p < 0.04) but no difference in intensive care unit length of stay (4.1 days vs. 4.7 days; p = 0.75) or discharge to skilled nursing facility (34.5% vs. 31.9%; p = 0.63). On subanalysis of patients who received quetiapine, 40% had ICP monitoring. Higher doses of quetiapine were independently associated with progressively lower ICP (β = -0.022 mm Hg/mg of quetiapine; p = 0.01) and higher CPP (β = 0.031 mm Hg/mg quetiapine; p = 0.01).

CONCLUSION

Quetiapine may decrease mortality and improve neurological outcomes in critically ill TBI patients. It has a dose-dependent effect to decrease ICP and increase CPP. Quetiapine may be a potential therapeutic modality in critically ill TBI patients, but further studies are required to explore these mechanisms.

LEVEL OF EVIDENCE

Systematic Review, level III.

The brain-gut axis: A prime therapeutic target in traumatic brain injury

Traumatic brain injury (TBI) is a significant cause of morbidity and mortality in trauma patients. The primary focus of treating TBI is to prevent additional injury to the damaged brain tissue, known as secondary brain injury. This treatment can include treating the body's inflammatory response. Despite promise in animal models, anti-inflammatory therapy has failed to improve outcomes in human patients, suggesting a more targeted and precise approach may be needed. There is a bidirectional axis between the intestine and the brain that contributes to this inflammation in acute and chronic injury. The mechanisms for this interaction are not completely understood, but there is evidence that neural, inflammatory, endocrine, and microbiome signals all participate in this process. Therapies that target the intestine as a source of inflammation have potential to lessen secondary brain injury and improve outcomes in TBI patients, but to develop these treatments we need to better understand the mechanisms behind this intestinal inflammatory response.

Unmetabolized quetiapine exerts an in vitro effect on innate immune cells by modulating inflammatory response and neutrophil extracellular trap formation

Quetiapine is an antipsychotic drug that is used to treat psychiatric and neurological disorders. Despite its efficiency and low-toxicity, quetiapine administration has been associated with undesirable side effects such as the development of low-grade inflammatory disorders and neutropenia states. As the liver rapidly metabolizes quetiapine to metabolites, the non-metabolized part of this molecule might play a role in immune alterations. In an in vitro study, this hypothesis was tested by exposing activated and inactivated RAW-264.7 macrophages and human neutrophils to unmetabolized quetiapine (u-QUE). Based on our findings, u-QUE was not cytotoxic to these cells. u-QUE differentially modulates macrophages according to their activation states. In inactivated macrophages, u-QUE induced a proinflammatory state as observed by an increase in cellular proliferation; increased levels of oxidative molecules (nitric oxide and superoxide), protein levels, and gene overexpression of proinflammatory cytokines (IL-1β, IL-6, and TNF-α); and decreased levels of IL-10, an anti-inflammatory cytokine. Conversely, on phytohemagglutinin (PHA)-activated macrophages, u-QUE exerted an anti-inflammatory effect. u-QUE induced neutrophil extracellular trap (NET) formation and increased the sensitivity of the neutrophils previously activated by exposure to dead yeast cells for NET formation. These results confirm the effect of quetiapine on macrophage and neutrophil function, which may be associated with the side effects of this psychopharmaceutical agent.

Repairing blood-CNS barriers: Future therapeutic approaches for neuropsychiatric disorders

Central nervous system (CNS) drug development faces significant difficulties that translate into high rates of failure and lack of innovation. The pathophysiology of neurological and psychiatric disorders often results in the breakdown of blood-CNS barriers, disturbing the CNS microenvironment and worsening disease progression. Therefore, restoring the integrity of blood-CNS barriers may have a beneficial influence in several CNS disorders and improve treatment outcomes. In this review, pathways that may be modulated to protect blood-CNS barriers from neuroinflammatory and oxidative insults are featured. First, the participation of the brain endothelium and glial cells in disruption processes is discussed. Then, the relevance of regulatory systems is analysed, specifically the hypothalamic-pituitary axis, the renin-angiotensin system, sleep and circadian rhythms, and glutamate neurotransmission. Lastly, compounds of endogenous and exogenous origin that are known to mediate the repair of blood-CNS barriers are presented. We believe that enhancing the protection of blood-CNS barriers is a promising therapeutic strategy to pursue in the future.

Role of quetiapine in protection of neurodegeneration after traumatic brain injury

OBJECTIVE

Schizophrenia is a chronic psychotic disorder in which patients experience positive and negative symptoms for over six months. Schizophrenia is associated with early mortality, with 40% of this excess mortality due to suicide. This is a case of patient with schizophrenia who was treated with quetiapine after suffering a traumatic brain injury and recovered enough to be discharged to a rehabilitation unit. This case illustrates the neuroprotective effects of quetiapine in treating neurologic deficits in a patient who recently suffered a traumatic brain injury.

METHOD

This is a case report of a patient with schizophrenia treated in the hospital setting. He was placed on quetiapine after suffering a traumatic brain injury due to a suicide attempt in which he shot himself with a nail gun.

RESULTS

The patient initially presented with neurologic deficits suggestive of traumatic brain injury (inattention, memory loss, muscle weakness) and psychosis from schizophrenia. He was treated with quetiapine and recovered enough to be discharged to a rehabilitation unit.

CONCLUSION

Quetiapine, a second-generation antipsychotic, has been shown to significantly decrease blood–brain barrier hyperpermeability by preserving tight junction integrity in small animal models. This anti-inflammatory effect may also help to preserve neurogenesis in patients with traumatic brain injury, as shown in this case. This case may help elucidate the nature of quetiapine’s neuroprotective effects in patients who have suffered traumatic brain injury and also highlights the need to further investigate other atypical antipsychotics and their potential neuroprotective role in treating traumatic brain injury.

Astrocyte-derived fatty acid-binding protein 7 protects blood-brain barrier integrity through a caveolin-1/MMP signaling pathway following traumatic brain injury

The astrocyte-endothelial cell interaction is crucial for normal brain homeostasis and blood-brain barrier (BBB) disruption in pathological conditions. However, the mechanism by which astrocytes control BBB integrity, especially after traumatic brain injury (TBI), remains unclear. Here, we present evidence that astrocyte-derived fatty acid-binding protein 7 (FABP7), a differentiation- and migration-associated molecule, may function as a modulator of BBB permeability in a rat weight-drop model of TBI. Immunohistochemical analysis revealed that TBI induced increased expression of FABP7 in astrocytes, accompanied by caveolin-1 (Cav-1) upregulation in endothelial cells. Administration of recombinant FABP7 significantly ameliorated TBI-induced neurological deficits, brain edema, and BBB permeability, concomitant with upregulation of endothelial Cav-1 and tight junction protein expression, while FABP7 knockdown resulted in the opposite effects. Furthermore, pretreatment with daidzein, a specific inhibitor of Cav-1, reversed the inhibitory effects of recombinant FABP7 on matrix metalloproteinase (MMP)-2/9 expression and abolished its BBB protection after TBI. Altogether, these findings suggest that astrocyte-derived FABP7 upregulation may represent an endogenous protective response to BBB disruption partly mediated through a Cav-1/MMP signaling pathway following TBI.

Sphingosine-1-phosphate protects against brain microvascular endothelial junctional protein disorganization and barrier dysfunction caused by alcohol

OBJECTIVE

S1P has known endothelial barrier-protective properties, but whether this extends to the BBB is unclear. We hypothesized that alcohol-induced disruption of brain microvascular endothelial barrier function and junctional protein organization can be ameliorated by S1P treatment.

METHODS

Cultured primary HBMEC monolayers were used to characterize endothelial-specific mechanisms of BBB regulation. TER and apparent permeability coefficients for albumin, dextran-4 kDa, and sodium fluorescein were used as indices of barrier function. Junctional localization of Claudin-5, VE-cadherin, and β-catenin was determined by immunofluorescence confocal microscopy. S1P was applied following treatment with alcohol.

RESULTS

Alcohol significantly impaired HBMEC TER. Application of S1P after alcohol treatment resulted in a hastened recovery to the baseline HBMEC TER. Alcohol-treated HBMEC had a significantly higher mean permeability than control that was reversed by S1P. Alcohol caused the formation of gaps between cells. Treatment with S1P (after alcohol) increased junctional localization of VE-Cadherin, Claudin-5, and β-catenin.

CONCLUSIONS

Alcohol impairs the barrier function and junctional organization of HBMEC monolayers. S1P enhanced barrier function and restored junctions in the presence of alcohol, and thus may be useful for restoring BBB function during alcohol intoxication.