Novel surrogate markers for acute brain damage: cerebrospinal fluid levels corrrelate with severity of ischemic neurodegeneration in the rat

The role of spectrin breakdown products in patients with traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Spectrin Breakdown Products (SBDPs) accumulate in the brain after traumatic brain injury (TBI) and are expected to become a potentially promising biomarker of TBI.

OBJECTIVE

This systematic review and meta-analysis were undertaken to evaluate the role of SBDPs in the diagnosis and prognosis of TBI.

METHODS

We systematically searched the following databases up to 31 October 2022: Ovid MEDLINE, PubMed, EMBASE, Cochrane Library, and Web of Science Database, and studies were only included if they had sufficient data on SBDP concentrations in TBI patients. We calculated the standardized mean differences (SMDs) and 95% confidence intervals (CIs) for continuous outcomes and assessed the potential publication bias by using Egger's test and funnel plots. The statistical analysis was conducted by RevMan 5.4 and Stata 17.

RESULTS

Of 1429 identified studies, 10 studies involving 417 participants were included in our systematic review and meta-analysis. The results demonstrated that serum and cerebrospinal fluid (CSF) SBDP concentrations were significantly increased in TBI compared to controls (SBDP120: SMD = 1.42, 95% CI = 0.71 ~ 2.12, P < 0.00001; SBDP145: SMD = 1.32, 95% CI = 0.78 ~ 1.86, P < 0.00001; SBDP150: SMD = 1.39, 95% CI = 0.97 ~ 1.80, P < 0.00001), and CSF SBDPs were significantly associated with poor functional outcomes (PFO) (SBDP145: SMD = 1.75, 95% CI = 1.37 ~ 2.13, P < 0.00001; SBDP150: SMD = 1.14, 95% CI = 0.75 ~ 1.52, P < 0.00001). In addition, CSF and serum SBDP145 are valuable in diagnosing TBI (AUC = 0.89, 95% CI = 0.80 ~ 0.99, P < 0.00001), and CSF SBDP145 also has diagnostic value for PFO (AUC = 0.80, 95% CI = 0.76 ~ 0.84, P < 0.00001).

CONCLUSIONS

The limited evidence supports that the SBDPs can be employed as potential biomarkers for the diagnosis and prognosis of TBI.

Fluid biomarkers in stroke: From animal models to clinical care

Stroke is a leading cause of death and disability worldwide. Stroke prevention, early diagnosis, and efficient acute treatment are priorities to successfully impact stroke death and disability. Fluid biomarkers may improve stroke differential diagnostic, patient stratification for acute treatment, and post-stroke individualized rehabilitation. In the present work, we characterized the use of stroke animal models in fluid biomarker research through a systematic review of PubMed and Scopus databases, followed by a literature review on the translation to the human stroke care setting and future perspectives in the field. We found increasing numbers of publications but with limited translation to the clinic. Animal studies are very heterogeneous, do not account for several human features present in stroke, and, importantly, only a minority of such studies used human cohorts to validate biomarker findings. Clinical studies have found appealing candidates, both protein and circulating nucleic acids, to contribute to a more personalized stroke care pathway. Still, brain tissue complexity and the fact that different brain pathologies share lesion biomarkers make this task challenging due to biomarker low specificity. Moreover, the study design and lack of validation cohorts may have precluded a formal integration of biomarkers in different steps of stroke diagnosis and treatment. To overcome such issues, recent pivotal studies on biomarker dynamics in individual patients are providing added value to diagnosis and anticipating patients' early prognosis. Presently, the most consistent protein biomarkers for stroke diagnosis and short- and long-term prognosis are associated with tissue damage at neuronal (TAU), axonal (NFL), or astroglial (GFAP and S100β) levels. Most promising nucleic acids are microRNAs (miR), due to their stability in plasma and ease of access. Still, clinical validation and standardized quantitation place them a step behind compared protein as stroke biomarkers. Ultimately, the definition of clinically relevant biomarker panels and optimization of fast and sensitive biomarker measurements in the blood, together with their combination with clinical and neuroimaging data, will pave the way toward personalized stroke care.

Modeling links softening of myelin and spectrin scaffolds of axons after a concussion to increased vulnerability to repeated injuries

Damage to the microtubule lattice, which serves as a rigid cytoskeletal backbone for the axon, is a hallmark mechanical initiator of pathophysiology after concussion. Understanding the mechanical stress transfer from the brain tissue to the axonal cytoskeleton is essential to determine the microtubule lattice's vulnerability to mechanical injury. Here, we develop an ultrastructural model of the axon's cytoskeletal architecture to identify the components involved in the dynamic load transfer during injury. Corroborative in vivo studies were performed using a gyrencephalic swine model of concussion via single and repetitive head rotational acceleration. Computational analysis of the load transfer mechanism demonstrates that the myelin sheath and the actin/spectrin cortex play a significant role in effectively shielding the microtubules from tissue stress. We derive failure maps in the space spanned by tissue stress and stress rate to identify physiological conditions in which the microtubule lattice can rupture. We establish that a softer axonal cortex leads to a higher susceptibility of the microtubules to failure. Immunohistochemical examination of tissue from the swine model of single and repetitive concussion confirms the presence of postinjury spectrin degradation, with more extensive pathology observed following repetitive injury. Because the degradation of myelin and spectrin occurs over weeks following the first injury, we show that softening of the myelin layer and axonal cortex exposes the microtubules to higher stress during repeated incidences of traumatic brain injuries. Our predictions explain how mechanical injury predisposes axons to exacerbated responses to repeated injuries, as observed in vitro and in vivo.

The Inferior Colliculus in Alcoholism and Beyond

Post-mortem neuropathological and in vivo neuroimaging methods have demonstrated the vulnerability of the inferior colliculus to the sequelae of thiamine deficiency as occurs in Wernicke-Korsakoff Syndrome (WKS). A rich literature in animal models ranging from mice to monkeys-including our neuroimaging studies in rats-has shown involvement of the inferior colliculi in the neural response to thiamine depletion, frequently accomplished with pyrithiamine, an inhibitor of thiamine metabolism. In uncomplicated alcoholism (i.e., absent diagnosable neurological concomitants), the literature citing involvement of the inferior colliculus is scarce, has nearly all been accomplished in preclinical models, and is predominately discussed in the context of ethanol withdrawal. Our recent work using novel, voxel-based analysis of structural Magnetic Resonance Imaging (MRI) has demonstrated significant, persistent shrinkage of the inferior colliculus using acute and chronic ethanol exposure paradigms in two strains of rats. We speculate that these consistent findings should be considered from the perspective of the inferior colliculi having a relatively high CNS metabolic rate. As such, they are especially vulnerable to hypoxic injury and may be provide a common anatomical link among a variety of disparate insults. An argument will be made that the inferior colliculi have functions, possibly related to auditory gating, necessary for awareness of the external environment. Multimodal imaging including diffusion methods to provide more accurate in vivo visualization and quantification of the inferior colliculi may clarify the roles of brain stem nuclei such as the inferior colliculi in alcoholism and other neuropathologies marked by altered metabolism.

14-3-3ζ protein protects against brain ischemia/reperfusion injury and induces BDNF transcription after MCAO in rat

Brain ischemia is a leading cause of death and disability worldwide that occurs when blood supply of the brain is disrupted. Brain-derived neurotrophic factor (BDNF) is a protective factor in neurodegenerative conditions. Nevertheless, there are some problems when exogenous BDNF is to be used in the clinic. 14-3-3ζ is a pro-survival highly-expressed protein in the brain that protects neurons against death. This study evaluates 14-3-3ζ effects on BDNF transcription at early time point after ischemia and its possible protective effects against ischemia damage. Human 14-3-3ζ protein was purified after expression. Rats were assigned into four groups, including sham, ischemia, and two treatment groups. Stereotaxic cannula implantation was carried out in the right cerebral ventricle. After one week, rats underwent middle cerebral artery occlusion (MCAO) surgery and received 14-3-3ζ (produced in our laboratory or standard form as control) in the middle of ischemia time. At 6 h of reperfusion after ischemia, brain parts containing the hippocampus, the cortex, the piriform cortex-amygdala and the striatum were collected for real time PCR analysis. At 24 h of reperfusion after ischemia, neurological function evaluation and infarction volume measurement were performed. The present study showed that 14-3-3ζ could up-regulate BDNF mRNA at early time point after ischemia in the hippocampus, in the cortex and in the piriform cortex-amygdala and could also improve neurological outcome and reduce infarct volume. It seems that 14-3-3ζ could be a candidate factor for increasing endogenous BDNF in the brain and a potential therapeutic factor against brain ischemia.

Stress primes microglial polarization after global ischemia: Therapeutic potential of progesterone

Despite the fact that stress is associated with increased risk of stroke and worsened outcome, most preclinical studies have ignored this comorbid factor, especially in the context of testing neuroprotective treatments. Preclinical research suggests that stress primes microglia, resulting in an enhanced reactivity to a subsequent insult and potentially increasing vulnerability to stroke. Ischemia-induced activated microglia can be polarized into a harmful phenotype, M1, which produces pro-inflammatory cytokines, or a protective phenotype, M2, which releases anti-inflammatory cytokines and neurotrophic factors. Selective modulation of microglial polarization by inhibiting M1 or stimulating M2 may be a potential therapeutic strategy for treating cerebral ischemia. Our laboratory and others have shown progesterone to be neuroprotective against ischemic stroke in rodents, but it is not known whether it will be as effective under a comorbid condition of chronic stress. Here we evaluated the neuroprotective effect of progesterone on the inflammatory response in the hippocampus after exposure to stress followed by global ischemia. We focused on the effects of microglial M1/M2 polarization and pro- and anti-inflammatory mediators in stressed ischemic animals. Male Sprague-Dawley rats were exposed to 8 consecutive days of social defeat stress and then subjected to global ischemia or sham surgery. The rats received intraperitoneal injections of progesterone (8mg/kg) or vehicle at 2h post-ischemia followed by subcutaneous injections at 6h and once every 24h post-injury for 7days. The animals were killed at 7 and 14days post-ischemia, and brains were removed and processed to assess outcome measures using histological, immunohistochemical and molecular biology techniques. Pre-ischemic stress (1) exacerbated neuronal loss and neurodegeneration as well as microglial activation in the selectively vulnerable CA1 hippocampal region, (2) dysregulated microglial polarization, leading to upregulation of both M1 and M2 phenotype markers, (3) increased pro-inflammatory cytokine expression, and (4) reduced anti-inflammatory cytokine and neurotrophic factor expression in the ischemic hippocampus. Treatment with progesterone significantly attenuated stress-induced microglia priming by modulating polarized microglia and the inflammatory environment in the hippocampus, the area most vulnerable to ischemic injury. Our findings can be taken to suggest that progesterone holds potential as a candidate for clinical testing in ischemic stroke where high stress may be a contributing factor.

Prognostic utility of neuroinjury biomarkers in post out-of-hospital cardiac arrest (OHCA) patient management

Despite aggressive intervention, patients who survive an out-of-hospital cardiac arrest (OHCA) generally have very poor prognoses, with nationwide survival rates of approximately 10-20%. Approximately 90% of survivors will have moderate to severe neurological injury ranging from moderate cognitive impairment to brain death. Currently, few early prognostic indicators are considered reliable enough to support patients' families and clinicians' in their decisions regarding medical futility. Blood biomarkers of neurological injury after OHCA may be of prognostic value in these cases. When most bodily tissues are oxygen-deprived, cellular metabolism switches from aerobic to anaerobic respiration. Neurons are a notable exception, however, being dependent solely upon aerobic respiration. Thus, after several minutes without circulating oxygen, neurons sustain irreversible damage, and certain measurable biomarkers are released into the circulation. Prior studies have demonstrated value in blood biomarkers in prediction of survival and neurologic impairment after OHCA. We hypothesize that understanding peptide biomarker kinetics in the early return of spontaneous circulation (ROSC) period, especially in the setting of refractory cardiac arrest, may assist clinicians in determining prognosis earlier in acute resuscitation. Specifically, during and after immediate resuscitation and return of ROSC, clinicians and families face a series of important questions regarding patient prognosis, futility of care and allocation of scarce resources such as the early initiation of extracorporeal cardiopulmonary resuscitation (ECPR). The ability to provide early prognostic information in this setting is highly valuable. Currently available, as well as potential biomarkers that could be good candidates in prognostication of neurological outcomes after OHCA or in the setting of refractory cardiac arrest will be reviewed and discussed.

Neuron-microglia interaction induced bi-directional cytotoxicity associated with calpain activation

Activated microglia release pro-inflammatory factors and calpain into the extracellular milieu, damaging surrounding neurons. However, mechanistic links to progressive neurodegeneration in disease such as multiple sclerosis (MS) remain obscure. We hypothesize that persistent damaged/dying neurons may also release cytotoxic factors and calpain into the media, which then activate microglia again. Thus, inflammation, neuronal damage, and microglia activation, i.e., bi-directional interaction between neurons and microglia, may be involved in the progressive neurodegeneration. We tested this hypothesis using two in vitro models: (i) the effects of soluble factors from damaged primary cortical neurons upon primary rat neurons and microglia and (ii) soluble factors released from CD3/CD28 activated peripheral blood mononuclear cells of MS patients on primary human neurons and microglia. The first model indicated that neurons due to injury with pro-inflammatory agents (IFN-γ) release soluble neurotoxic factors, including COX-2, reactive oxygen species, and calpain, thus activating microglia, which in turn released neurotoxic factors as well. This repeated microglial activation leads to persistent inflammation and neurodegeneration. The released calpain from neurons and microglia was confirmed by the use of calpain inhibitor calpeptin or SNJ-1945 as well as μ- and m-calpain knock down using the small interfering RNA (siRNA) technology. Our second model using activated peripheral blood mononuclear cells, a source of pro-inflammatory Th1/Th17 cytokines and calpain released from auto-reactive T cells, corroborated similar results in human primary cell cultures and confirmed calpain to be involved in progressive MS. These insights into reciprocal paracrine regulation of cell injury and calpain activation in the progressive phase of MS, Parkinson's disease, and other neurodegenerative diseases suggest potentially beneficial preventive and therapeutic strategies, including calpain inhibition.

Interactions between Flow Oscillations and Biochemical Parameters in the Cerebrospinal Fluid

The equilibrium between the ventricular and lumbar cerebrospinal fluid (CSF) compartments may be disturbed (in terms of flow and biochemistry) in patients with chronic hydrocephalus (CH). Using flow magnetic resonance imaging (MRI) and CSF assays, we sought to determine whether changes in CSF were associated with biochemical alterations. Nine elderly patients with CH underwent phase-contrast MRI. An index of CSF dynamics (Idyn) was defined as the product of the lumbar and ventricular CSF flows. During surgery, samples of CSF were collected from the lumbar and ventricular compartments and assayed for chloride, glucose and total protein. The lumbar/ventricular (L/V) ratio was calculated for each analyte. The ratio between measured and expected levels (Ibioch) was calculated for each analyte and compared with Idyn. Idyn varied from 0 to 100.10(3)μl(2).s(2). In contrast to the L/V ratios for chloride and glucose, the L/V ratio for total protein varied markedly from one patient to another (mean ± standard deviation (SD): 2.63 ± 1.24). The Ibioch for total protein was strongly correlated with the corresponding Idyn (Spearman's R: 0.98; p < 5 × 10(-5)).We observed correlated alterations in CSF flow and biochemical parameters in patients with CH. Our findings also highlight the value of dynamic flow analysis in the interpretation of data on CSF biochemistry.

SNTF immunostaining reveals previously undetected axonal pathology in traumatic brain injury

Diffuse axonal injury (DAI) is a common feature of severe traumatic brain injury (TBI) and may also be a predominant pathology in mild TBI or "concussion". The rapid deformation of white matter at the instant of trauma can lead to mechanical failure and calcium-dependent proteolysis of the axonal cytoskeleton in association with axonal transport interruption. Recently, a proteolytic fragment of alpha-II spectrin, "SNTF", was detected in serum acutely following mild TBI in patients and was prognostic for poor clinical outcome. However, direct evidence that this fragment is a marker of DAI has yet to be demonstrated in either humans following TBI or in models of mild TBI. Here, we used immunohistochemistry (IHC) to examine for SNTF in brain tissue following both severe and mild TBI. Human severe TBI cases (survival <7d; n = 18) were compared to age-matched controls (n = 16) from the Glasgow TBI archive. We also examined brains from an established model of mild TBI at 6, 48 and 72 h post-injury versus shams. IHC specific for SNTF was compared to that of amyloid precursor protein (APP), the current standard for DAI diagnosis, and other known markers of axonal pathology including non-phosphorylated neurofilament-H (SMI-32), neurofilament-68 (NF-68) and compacted neurofilament-medium (RMO-14) using double and triple immunofluorescent labeling. Supporting its use as a biomarker of DAI, SNTF immunoreactive axons were observed at all time points following both human severe TBI and in the model of mild TBI. Interestingly, SNTF revealed a subpopulation of degenerating axons, undetected by the gold-standard marker of transport interruption, APP. While there was greater axonal co-localization between SNTF and APP after severe TBI in humans, a subset of SNTF positive axons displayed no APP accumulation. Notably, some co-localization was observed between SNTF and the less abundant neurofilament subtype markers. Other SNTF positive axons, however, did not co-localize with any other markers. Similarly, RMO-14 and NF-68 positive axonal pathology existed independent of SNTF and APP. These data demonstrate that multiple pathological axonal phenotypes exist post-TBI and provide insight into a more comprehensive approach to the neuropathological assessment of DAI.

Examining the Neural and Astroglial Protective Effects of Cellular Prion Protein Expression and Cell Death Protease Inhibition in Mouse Cerebrocortical Mixed Cultures

Overexpression of cellular prion protein, PrP(C), has cytoprotective effects against neuronal injuries. Inhibition of cell death-associated proteases such as necrosis-linked calpain and apoptosis-linked caspase are also neuroprotective. Here, we systematically studied how PrP(C) expression levels and cell death protease inhibition affect cytotoxic challenges to both neuronal and glial cells in mouse cerebrocortical mixed cultures (CCM). Primary CCM derived from three mouse lines expressing no (PrP(C) knockout mice (PrPKO)), normal (wild-type (wt)), or high (tga20) levels of PrP(C) were subjected to necrotic challenge (calcium ionophore A23187) and apoptotic challenge (staurosporine (STS)). CCM which originated from tga20 mice provided the most robust neuron-astroglia protective effects against necrotic and early apoptotic cell death (lactate dehydrogenase (LDH) release) at 6 h but subsequently lost its cytoprotective effects. In contrast, PrPKO-derived cultures displayed elevated A23187- and STS-induced cell death at 24 h. Calpain inhibitor SNJ-1945 protected against A23187 challenge at 6 h in CCM from all three mouse lines but protected only against A23187 and STS treatments by 24 h in the PrPKO line. In parallel, caspase inhibitor Z-D-DCB protected against pro-apoptotic STS challenge at 6 and 24 h. Furthermore, we also examined αII-spectrin breakdown products (primarily from neurons) and glial fibrillary acidic protein (GFAP) breakdown products (from astroglia) as cytoskeletal proteolytic biomarkers. Overall, it appeared that both neurons and astroglial cells were less vulnerable to proteolytic attack during A23187 and STS challenges in tga20-derived cultures but more vulnerable in PrPKO-derived cultures. In addition, calpain and caspase inhibitors provide further protection against respective protease attacks on these neuronal and glial cytoskeletal proteins in CCM regardless of mouse-line origin. Lastly, some synergistic cytoprotective effects between PrP(C) expression and addition of cell death-linked protease inhibitors were also observed.

Neuronal and glia-related biomarkers in cerebrospinal fluid of patients with acute ischemic stroke

BACKGROUND

Cerebral ischemia promotes morphological reactions of the neurons, astrocytes, oligodendrocytes, and microglia in experimental studies. Our aim was to examine the profile of CSF (cerebrospinal fluid) biomarkers and their relation to stroke severity and degree of white matter lesions (WML).

METHODS

A total of 20 patients (mean age 76 years) were included within 5–10 days after acute ischemic stroke (AIS) onset. Stroke severity was assessed using NIHSS (National Institute of Health stroke scale). The age-related white matter changes (ARWMC) scale was used to evaluate the extent of WML on CT-scans. The concentrations of specific CSF biomarkers were analyzed.

RESULTS

Patients with AIS had significantly higher levels of NFL (neurofilament, light), T-tau, myelin basic protein (MBP), YKL-40, and glial fibrillary acidic protein (GFAP) compared with controls; T-Tau, MBP, GFAP, and YKL-40 correlated with clinical stroke severity, whereas NFL correlated with severity of WML (tested by Mann–Whitney test).

CONCLUSIONS

Several CSF biomarkers increase in AIS, and they correlate to clinical stroke severity. However, only NFL was found to be a marker of degree of WML.

Evidence That the Blood Biomarker SNTF Predicts Brain Imaging Changes and Persistent Cognitive Dysfunction in Mild TBI Patients

Although mild traumatic brain injury (mTBI), or concussion, is not typically associated with abnormalities on computed tomography (CT), it nevertheless causes persistent cognitive dysfunction for many patients. Consequently, new prognostic methods for mTBI are needed to identify at risk cases, especially at an early and potentially treatable stage. Here, we quantified plasma levels of the neurodegeneration biomarker calpain-cleaved αII-spectrin N-terminal fragment (SNTF) from 38 participants with CT-negative mTBI, orthopedic injury (OI), and normal uninjured controls (UCs) (age range 12–30 years), and compared them with findings from diffusion tensor imaging (DTI) and long-term cognitive assessment. SNTF levels were at least twice the lower limit of detection in 7 of 17 mTBI cases and in 3 of 13 OI cases, but in none of the UCs. An elevation in plasma SNTF corresponded with significant differences in fractional anisotropy and the apparent diffusion coefficient in the corpus callosum and uncinate fasciculus measured by DTI. Furthermore, increased plasma SNTF on the day of injury correlated significantly with cognitive impairment that persisted for at least 3 months, both across all study participants and also among the mTBI cases by themselves. The elevation in plasma SNTF in the subset of OI cases, accompanied by corresponding white matter and cognitive abnormalities, raises the possibility of identifying undiagnosed cases of mTBI. These data suggest that the blood level of SNTF on the day of a CT-negative mTBI may identify a subset of patients at risk of white matter damage and persistent disability. SNTF could have prognostic and diagnostic utilities in the assessment and treatment of mTBI.

Therapy development for diffuse axonal injury

Diffuse axonal injury (DAI) remains a prominent feature of human traumatic brain injury (TBI) and a major player in its subsequent morbidity. The importance of this widespread axonal damage has been confirmed by multiple approaches including routine postmortem neuropathology as well as advanced imaging, which is now capable of detecting the signatures of traumatically induced axonal injury across a spectrum of traumatically brain-injured persons. Despite the increased interest in DAI and its overall implications for brain-injured patients, many questions remain about this component of TBI and its potential therapeutic targeting. To address these deficiencies and to identify future directions needed to fill critical gaps in our understanding of this component of TBI, the National Institute of Neurological Disorders and Stroke hosted a workshop in May 2011. This workshop sought to determine what is known regarding the pathogenesis of DAI in animal models of injury as well as in the human clinical setting. The workshop also addressed new tools to aid in the identification of this axonal injury while also identifying more rational therapeutic targets linked to DAI for continued preclinical investigation and, ultimately, clinical translation. This report encapsulates the oral and written components of this workshop addressing key features regarding the pathobiology of DAI, the biomechanics implicated in its initiating pathology, and those experimental animal modeling considerations that bear relevance to the biomechanical features of human TBI. Parallel considerations of alternate forms of DAI detection including, but not limited to, advanced neuroimaging, electrophysiological, biomarker, and neurobehavioral evaluations are included, together with recommendations for how these technologies can be better used and integrated for a more comprehensive appreciation of the pathobiology of DAI and its overall structural and functional implications. Lastly, the document closes with a thorough review of the targets linked to the pathogenesis of DAI, while also presenting a detailed report of those target-based therapies that have been used, to date, with a consideration of their overall implications for future preclinical discovery and subsequent translation to the clinic. Although all participants realize that various research gaps remained in our understanding and treatment of this complex component of TBI, this workshop refines these issues providing, for the first time, a comprehensive appreciation of what has been done and what critical needs remain unfulfilled.

Clinical Relevance of Biomarkers for Traumatic Brain Injury

Approximately 1.4 million people in the United States sustain a traumatic brain injury (TBI) each year, resulting in more than 235 000 hospitalizations and 50 000 deaths. An estimated 5.3 million Americans have current long-term disabilities as a result of TBI, which results in an estimated $60 billion in healthcare expenditures. Mild TBI (mTBI), which accounts for 80% to 90% of all cases, is the most prevalent form of brain injury in athletes. Many of these traumas still remain undetected, as they are difficult to diagnose. New biomarkers of TBI may allow more rapid diagnosis of TBI, improving early identification and treatment, and could help to predict clinical outcome. The field of TBI biomarkers is rapidly evolving. This chapter will discuss some of the most clinically relevant biomarkers for TBI that have been recently studied in human subjects.

Increased cytochrome c in rat cerebrospinal fluid after cardiac arrest and its effects on hypoxic neuronal survival

Cerebrospinal fluid (CSF) proteins may be useful biomarkers of neuronal death and ultimate prognosis after hypoxic-ischemic brain injury. Cytochrome c has been identified in the CSF of children following traumatic brain injury. Cytochrome c is required for cellular respiration but it is also a central component of the intrinsic pathway of apoptosis. Thus, in addition to serving as a biomarker, cytochrome c release into CSF may have an effect upon survival of adjacent neurons. In this study, we use Western blot and ELISA to show that cytochrome c is elevated in CSF obtained from pediatric rats following resuscitation from cardiac arrest. Using biotinylated human cytochrome c in culture media we show that cytochrome c crosses the cell membrane and is incorporated into mitochondria of neurons exposed to anoxia. Lastly, we show that addition of human cytochrome c to primary neuronal culture exposed to anoxia improves survival. To our knowledge, this is the first study to show cytochrome c is elevated in CSF following hypoxic ischemic brain injury. Results from primary neuronal culture suggest that extracellular cytochrome c is able to cross the cell membrane of injured neurons, incorporate into mitochondria, and promote survival following anoxia.

Proteomic analysis of rat plasma following transient focal cerebral ischemia

AIM

This study aimed to identify plasma protein changes in a rat model of ischemic stroke using a proteomic approach.

MATERIALS & METHODS

Four male Sprague-Dawley rats (3-6 months old) were subjected to 90 min of left middle cerebral artery occlusion under anesthesia with 1.5% isoflurane in O(2)/air followed by 24-h reperfusion. Blood samples (~100 µl) were collected at baseline, at the end of 90-min middle cerebral artery occlusion and at 24-h postreperfusion. Brain injuries were assessed by MRI at 24-h postreperfusion. Quantitative comparison of global plasma protein expression was performed using 2D differential in-gel electrophoresis. Differentially expressed protein spots were identified using peptide sequencing tandem mass spectrometry.

RESULTS

These rats had clear brain infarction in the left hemisphere detected by MRI. Thirty-three protein spots of plasma samples were differentially expressed following focal cerebral ischemia/reperfusion. These protein spots belonged to eight proteins. Six of them (α2-macroglobulin, complement C3, inter-α- trypsin inhibitor heavy chain H3, serum albumin, haptoglobin and transthyretin), which are a class of acute-phase proteins, changed significantly.

CONCLUSION

This study describes the responses of young rats to focal cerebral ischemia and suggests that future studies should use aged animals to better mimic the clinical ischemic stroke setting.

Evidence that a panel of neurodegeneration biomarkers predicts vasospasm, infarction, and outcome in aneurysmal subarachnoid hemorrhage

Biomarkers for neurodegeneration could be early prognostic measures of brain damage and dysfunction in aneurysmal subarachnoid hemorrhage (aSAH) with clinical and medical applications. Recently, we developed a new panel of neurodegeneration biomarkers, and report here on their relationships with pathophysiological complications and outcomes following severe aSAH. Fourteen patients provided serial cerebrospinal fluid samples for up to 10 days and were evaluated by ultrasonography, angiography, magnetic resonance imaging, and clinical examination. Functional outcomes were assessed at hospital discharge and 6-9 months thereafter. Eight biomarkers for acute brain damage were quantified: calpain-derived α-spectrin N- and C-terminal fragments (CCSntf and CCSctf), hypophosphorylated neurofilament H,14-3-3 β and ζ, ubiquitin C-terminal hydrolase L1, neuron-specific enolase, and S100β. All 8 biomarkers rose up to 100-fold in a subset of patients. Better than any single biomarker, a set of 6 correlated significantly with cerebral vasospasm, brain infarction, and poor outcome. Furthermore, CSF levels of 14-3-3β, CCSntf, and NSE were early predictors of subsequent moderate-to-severe vasospasm. These data provide evidence that a panel of neurodegeneration biomarkers may predict lasting brain dysfunction and the pathophysiological processes that lead to it following aSAH. The panel may be valuable as surrogate endpoints for controlled clinical evaluation of treatment interventions and for guiding aSAH patient care.

Heat shock proteins as biomarkers for the rapid detection of brain and spinal cord ischemia: a review and comparison to other methods of detection in thoracic aneurysm repair

The heat shock proteins (HSPs) are members of highly conserved families of molecular chaperones that have multiple roles in vivo. We discuss the HSPs in general, and Hsp70 and Hsp27 in particular, and their rapid induction by severe stress in the context of tissue and organ expression in physiology and disease. We describe the current state of knowledge of the relationship and interactions between extra- and intracellular HSPs and describe mechanisms and significance of extracellular expression of HSPs. We focus on the role of the heat shock proteins as biomarkers of central nervous system (CNS) ischemia and other severe stressors and discuss recent and novel technologies for rapid measurement of proteins in vivo and ex vivo. The HSPs are compared to other proposed small molecule biomarkers for detection of CNS injury and to other methods of detecting brain and spinal cord ischemia in real time. While other biomarkers may be of use in prognosis and in design of appropriate therapies, none appears to be as rapid as the HSPs; therefore, no other measurement appears to be of use in the immediate detection of ongoing severe ischemia with the intention to immediately intervene to reduce the severity or risk of permanent damage.

Glutamate enhances the surface distribution and release of Munc18 in cerebral cortical neurons

OBJECTIVE

Munc18 is considered as an intracellular protein that plays an important role in exocytosis of neurotransmitters. Previous studies have demonstrated the presence of autoantibodies against Munc18 in a subgroup of Rasmussen's encephalitis patients. However, the machinery of Munc18 autoimmunity is still elusive. The present study was aimed to investigate Munc18 release from primary cultured neurons, Munc18 distribution on the outer plasma membrane of neurons, and the neurotoxicity of Munc18 antibody.

METHODS

The cerebral cortical neurons from embryonic day 17 Sprague-Dawley rats were prepared and cultured in neurobasal medium. The proteins in culture medium were precipitated with 10 % trichloroacetic acid, and analyzed by immunoblotting. The proteins on neuronal surface were biotinylated with EZ-Link-sulfo-NHS-LC-Biotin, and collected with avidin-conjugated agarose beads followed by immunoblotting analysis. For cell surface immunofluorescent staining, the living neurons were labeled with anti-Munc18 antibody at 4 degrees C. Neuronal injury was assessed by lactate dehydrogenase(LDH) release.

RESULTS

Munc18 was detected in culture medium by immunoblotting analysis. After treatment with 50 micromol/L glutamate for 1 h, Munc18 content in medium was increased. Meanwhile, beta-actin and syntaxin1 were not detected in culture medium, and LDH release was not significantly increased. Moreover, glutamate enhanced Munc18 distribution on outer plasma membrane. Living neuron staining also demonstrated the localization of Munc18 on neuronal surface after glutamate treatment, especially at contacting regions between neurons. Glutamate-induced increase of surface Munc18 distribution was suppressed by NMDA receptor antagonist MK801, but not by AMPA receptor antagonist NBQX. Moreover, compared with c-Fos antibody, Munc18 antibody could induce neuronal injury, when culture medium contained the components of serum.

CONCLUSION

A portion of Munc18 can be released from neurons or distributed on neuronal surface, which can be enhanced by glutamate treatment via activation of NMDA receptors. Besides, Munc18 antibody-induced neuronal injury depends on the serum components.

Ubiquitin C-terminal hydrolase-L1 as a biomarker for ischemic and traumatic brain injury in rats

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), also called neuronal-specific protein gene product 9.5, is a highly abundant protein in the neuronal cell body and has been identified as a possible biomarker on the basis of a recent proteomic study. In this study, we examined whether UCH-L1 was significantly elevated in cerebrospinal fluid (CSF) following controlled cortical impact (CCI) and middle cerebral artery occlusion (MCAO; model of ischemic stroke) in rats. Quantitative immunoblots of rat CSF revealed a dramatic elevation of UCH-L1 protein 48 h after severe CCI and as early as 6 h after mild (30 min) and severe (2 h) MCAO. A sandwich enzyme-linked immunosorbent assay constructed to measure UCH-L1 sensitively and quantitatively showed that CSF UCH-L1 levels were significantly elevated as early as 2 h and up to 48 h after CCI. Similarly, UCH-L1 levels were also significantly elevated in CSF from 6 to 72 h after 30 min of MCAO and from 6 to 120 h after 2 h of MCAO. These data are comparable to the profile of the calpain-produced alphaII-spectrin breakdown product of 145 kDa biomarker. Importantly, serum UCH-L1 biomarker levels were also significantly elevated after CCI. Similarly, serum UCH-L1 levels in the 2-h MCAO group were significantly higher than those in the 30-min group. Taken together, these data from two rat models of acute brain injury strongly suggest that UCH-L1 is a candidate brain injury biomarker detectable in biofluid compartments (CSF and serum).

Proteomic and phosphoproteomic analyses of the soluble fraction following acute spinal cord contusion in rats

Traumatic spinal cord injury (SCI) causes marked neuropathological changes in the spinal cord, resulting in limited functional recovery. Currently, there are no effective treatments, and the mechanisms underlying these neuropathological changes are not completely understood. In this study, two-dimensional gel electrophoresis coupled with mass spectrometry was used to investigate injury-related changes in the abundance (SYPRO Ruby stain) and phosphorylation (Pro-Q Diamond stain) of proteins from the soluble fraction of the lesion epicenter at 24 h following SCI. Over 1500 SYPRO Ruby-stained spots and 100 Pro-Q Diamond-stained spots were examined. We identified 26 unique proteins within 38 gel spots that differentially changed in abundance, phosphorylation, or both in response to SCI. Protein redundancies among the gel spots were likely due to differences in proteolysis, post-translational modifications, and the existence of isoforms. The proteins affected were blood-related proteins, heat-shock proteins, glycolytic enzymes, antioxidants, and proteins that function in cell structure, cell signaling, DNA damage, and protein degradation. These protein changes post injury may suggest additional avenues of investigation into the underlying molecular mechanisms responsible for the pathophysiological consequences of SCI.

Reactive microgliosis: extracellular micro-calpain and microglia-mediated dopaminergic neurotoxicity

Microglia, the innate immune cells in the brain, can become chronically activated in response to dopaminergic neuron death, fuelling a self-renewing cycle of microglial activation followed by further neuron damage (reactive microgliosis), which is implicated in the progressive nature of Parkinson's disease. Here, we use an in vitro approach to separate neuron injury factors from the cellular actors of reactive microgliosis and discover molecular signals responsible for chronic and toxic microglial activation. Upon injury with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium, N27 cells (dopaminergic neuron cell line) released soluble neuron injury factors that activated microglia and were selectively toxic to dopaminergic neurons in mixed mesencephalic neuron-glia cultures through nicotinamide adenine dinucleotide phosphate oxidase. mu-Calpain was identified as a key signal released from damaged neurons, causing selective dopaminergic neuron death through activation of microglial nicotinamide adenine dinucleotide phosphate oxidase and superoxide production. These findings suggest that dopaminergic neurons may be inherently susceptible to the pro-inflammatory effects of neuron damage, i.e. reactive microgliosis, providing much needed insight into the chronic nature of Parkinson's disease.

A panel of neuron-enriched proteins as markers for traumatic brain injury in humans

Surrogate markers have enormous potential for contributing to the diagnosis, prognosis, and therapeutic evaluation of acute brain damage, but extensive prior study of individual candidates has not yielded a biomarker in widespread clinical practice. We hypothesize that a panel of neuron-enriched proteins measurable in cerebrospinal fluid (CSF) and blood should vastly improve clinical evaluation and therapeutic management of acute brain injuries. Previously, we developed such a panel based initially on the study of protein release from degenerating cultured neurons, and subsequently on rodent models of traumatic brain injury (TBI) and ischemia, consisting of 14-3-3beta, 14-3-3zeta, three distinct phosphoforms of neurofilament H, ubiquitin hydrolase L1, neuron-specific enolase, alpha-spectrin, and three calpain- and caspase-derived fragments of alpha-spectrin. In the present study, this panel of 11 proteins was evaluated as CSF and serum biomarkers for severe TBI in humans. By quantitative Western blotting and sandwich immunoassays, the CSF protein levels were near or below the limit of detection in pre-surgical and most normal pressure hydrocephalus (NPH) controls, but following TBI nine of the 11 were routinely elevated in CSF. Whereas different markers peaked coordinately, the time to peak varied across TBI cases from 24-96 h post-injury. In serum, TBI increased all four members of the marker panel for which sandwich immunoassays are currently available: a calpain-derived NH(2)-terminal alpha-spectrin fragment and the three neurofilament H phosphoforms. Our results identify neuron-enriched proteins that may serve as a panel of CSF and blood surrogate markers for the minimally invasive detection, management, mechanistic, and therapeutic evaluation of human TBI.

Calcium-activated calpain-2 is a mediator of beta cell dysfunction and apoptosis in type 2 diabetes

The islet in type 2 diabetes (T2DM) and the brain in neurodegenerative diseases share progressive cell dysfunction, increased apoptosis, and accumulation of locally expressed amyloidogenic proteins (islet amyloid polypeptide (IAPP) in T2DM). Excessive activation of the Ca(2+)-sensitive protease calpain-2 has been implicated as a mediator of oligomer-induced cell death and dysfunction in neurodegenerative diseases. To establish if human IAPP toxicity is mediated by a comparable mechanism, we overexpressed human IAPP in rat insulinoma cells and freshly isolated human islets. Pancreas was also obtained at autopsy from humans with T2DM and nondiabetic controls. We report that overexpression of human IAPP leads to the formation of toxic oligomers and increases beta cell apoptosis mediated by increased cytosolic Ca(2+) and hyperactivation of calpain-2. Cleavage of alpha-spectrin, a marker of calpain hyperactivation, is increased in beta cells in T2DM. We conclude that overactivation of Ca(2+)-calpain pathways contributes to beta cell dysfunction and apoptosis in T2DM.

Alpha II-spectrin breakdown products serve as novel markers of brain injury severity in a canine model of hypothermic circulatory arrest

BACKGROUND

The development of specific biomarkers to aid in the diagnosis and prognosis of neuronal injury is of paramount importance in cardiac surgery. Alpha II-spectrin is a structural protein abundant in neurons of the central nervous system and cleaved into signature fragments by proteases involved in necrotic and apoptotic cell death. We measured cerebrospinal fluid alpha II-spectrin breakdown products (alphaII-SBDPs) in a canine model of hypothermic circulatory arrest (HCA) and cardiopulmonary bypass.

METHODS

Canine subjects were exposed to either 1 hour of HCA (n = 8; mean lowest tympanic temperature 18.0 +/- 1.2 degrees C) or standard cardiopulmonary bypass (n = 7). Cerebrospinal fluid samples were collected before treatment and 8 and 24 hours after treatment. Using polyacrylamide gel electrophoresis and immunoblotting, SBDPs were isolated and compared between groups using computer-assisted densitometric scanning. Necrotic versus apoptotic cell death was indexed by measuring calpain and caspase-3 cleaved alphaII-SBDPs (SBDP 145+150 and SBDP 120, respectively).

RESULTS

Animals undergoing HCA demonstrated mild patterns of histologic cellular injury and clinically detectable neurologic dysfunction. Calpain-produced alphaII-SBDPs (150 kDa+145 kDa bands-necrosis) 8 hours after HCA were significantly increased (p = 0.02) as compared with levels before HCA, and remained elevated at 24 hours after HCA. In contrast, caspase-3 alphaII-SBDP (120 kDa band-apoptosis) was not significantly increased. Animals receiving cardiopulmonary bypass did not demonstrate clinical or histologic evidence of injury, with no increases in necrotic or apoptotic cellular markers.

CONCLUSIONS

We report the use of alphaII-SBDPs as markers of neurologic injury after cardiac surgery. Our analysis demonstrates that calpain- and caspase-produced alphaII-SBDPs may be an important and novel marker of neurologic injury after HCA.

Detection of protein biomarkers using high-throughput immunoblotting following focal ischemic or penetrating ballistic-like brain injuries in rats

PRIMARY OBJECTIVE

Recent efforts have been aimed at developing a panel of protein biomarkers for the diagnosis/prognosis of the neurological damage associated with acute brain injury.

METHODS AND PROCEDURES

This study utilized high-throughput immunoblotting (HTPI) technology to compare changes between two animal models of acute brain injury: penetrating ballistic-like brain injury (PBBI) which mimics the injury created by a gunshot wound and transient middle cerebral artery occlusion (MCAo) which is a model of stroke. Brain and blood were collected at 24-hours post-injury.

MAIN OUTCOMES AND RESULTS

This study identified the changes in 18 proteins following PBBI and 17 proteins following MCAo out of a total of 998 screened proteins. Distinct differences were observed between the two models: five proteins were up- or down-regulated in both models, 23 proteins changed in only one model and one protein was differentially expressed. Western blots were used to verify HTPI results for selected proteins with measurable changes observed in both blood and brain for the proteins STAT3, Tau, PKA RII beta, 14-3-3 epsilon and p43/EMAPII.

CONCLUSIONS

These results suggest distinct post-injury protein profiles between brain injury types (traumatic vs. ischemic) that will facilitate strategies aimed at the differential diagnosis and prognosis of acute brain injury.

Molecular markers of radiation-related normal tissue toxicity

Over the past five decades, those interested in markers of radiation effect have focused primarily on tumor response. More recently, however, the view has broadened to include irradiated normal tissues-markers that predict unusual risk of side-effects, prognosticate during the prodromal and therapeutic phases, diagnose a particular toxicity as radiation-related, and, in the case of bioterror, allow for tissue-specific biodosimetry. Currently, there are few clinically useful radiation-related biomarkers. Notably, levels of some hormones such as thyroid-stimulating hormone (TSH) have been used successfully as markers of dysfunction, indicative of the need for replacement therapy, and for prevention of cancers. The most promising macromolecular markers are cytokines: TGFbeta, IL-1, IL-6, and TNFalpha being lead molecules in this class as both markers and targets for therapy. Genomics and proteomics are still in nascent stages and are actively being studied and developed.

Calpain-mediated signaling mechanisms in neuronal injury and neurodegeneration

Calpain is a ubiquitous calcium-sensitive protease that is essential for normal physiologic neuronal function. However, alterations in calcium homeostasis lead to persistent, pathologic activation of calpain in a number of neurodegenerative diseases. Pathologic activation of calpain results in the cleavage of a number of neuronal substrates that negatively affect neuronal structure and function, leading to inhibition of essential neuronal survival mechanisms. In this review, we examine the mechanistic underpinnings of calcium dysregulation resulting in calpain activation in the acute neurodegenerative diseases such as cerebral ischemia and in the chronic neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, prion-related encephalopathy, and amylotrophic lateral sclerosis. The premise of this paper is that analysis of the signaling and transcriptional consequences of calpain-mediated cleavage of its various substrates for any neurodegenerative disease can be extrapolated to all of the neurodegenerative diseases vulnerable to calcium dysregulation.

Biomarker evidence for mild central nervous system injury after surgically-induced circulation arrest

Previously, we identified 14-3-3 beta and zeta isoforms and proteolytic fragments of alpha-spectrin as proteins released from degenerating neurons that also rise markedly in cerebrospinal fluid (CSF) following experimental brain injury or ischemia in rodents, but these proteins have not been studied before as potential biomarkers for ischemic central nervous system injury in humans. Here we describe longitudinal analysis of these proteins along with the neuron-enriched hypophosphorylated neurofilament H (pNFH) and the deubiquitinating enzyme UCH-L1 in lumbar CSF samples from 19 surgical cases of aortic aneurysm repair, 7 involving cardiopulmonary bypass with deep hypothermic circulatory arrest (DHCA). CSF levels of the proteins were near the lower limit of detection by Western blot or enzyme-linked fluorescence immunoassay at the onset of surgical procedures, but increased substantially in a subset of cases, typically within 12-24 h. All cases involving DHCA were characterized by >3-fold elevations in CSF levels of the two 14-3-3 isoforms, UCH-L1, and pNFH. Six of 7 also exhibited marked increases in alpha-spectrin fragments generated by calpain, a protease known to trigger necrotic neurodegeneration. Among cases involving aortic cross-clamping but not DHCA, the proteins rose in CSF preferentially in the subset experiencing acute neurological complications. Our results suggest the neuron-enriched 14-3-3beta, 14-3-3zeta, pNFH, UCH-L1, and calpain-cleaved alpha-spectrin may serve as a panel of biomarkers with clinical potential for the detection and management of ischemic central nervous system injury, including for mild damage associated with surgically-induced circulation arrest.

Clinical significance of alphaII-spectrin breakdown products in cerebrospinal fluid after severe traumatic brain injury

Following traumatic brain injury (TBI), the cytoskeletal protein alpha-II-spectrin is proteolyzed by calpain and caspase-3 to signature breakdown products. To determine whether alpha -II-spectrin proteolysis is a potentially reliable biomarker for TBI in humans, the present study (1) examined levels of spectrin breakdown products (SBDPs) in cerebrospinal fluid (CSF) from adults with severe TBI and (2) examined the relationship between these levels, severity of injury, and clinical outcome. This prospective case control study enrolled 41 patients with severe TBI, defined by a Glasgow Coma Scale (GCS) score of < or =8, who underwent intraventricular intracranial pressure monitoring. Patients without TBI requiring CSF drainage for other medical reasons served as controls. Ventricular CSF was sampled from each patient at 6, 12, 24, 48, 72, 96, and 120 h following TBI and analyzed for SBDPs. Outcome was assessed using the Glasgow Outcome Score (GOS) 6 months after injury. Calpain and caspase-3 mediated SBDP levels in CSF were significantly increased in TBI patients at several time points after injury, compared to control subjects. The time course of calpain mediated SBDP150 and SBDP145 differed from that of caspase-3 mediated SBDP120 during the post-injury period examined. Mean SBDP densitometry values measured early after injury correlated with severity of injury, computed tomography (CT) scan findings, and outcome at 6 months post-injury. Taken together, these results support that alpha -II-spectrin breakdown products are potentially useful biomarker of severe TBI in humans. Our data further suggests that both necrotic/oncotic and apoptotic cell death mechanisms are activated in humans following severe TBI, but with a different time course after injury.

Activities of endogenous antioxidant enzymes in the cerebrospinal fluid and the hippocampus after transient forebrain ischemia in rat

The activity of SOD and CAT was measured in controls and 5 h after 5, 10 and 15 min of ischemia, as well as 1 or 2 days after 10 min of ischemia in the hippocampus and in the CSF. A significant increase in total SOD activity 5 h after ischemia was caused mainly by increased CuZn-SOD activity. The highest values were measured 5 h after 5 min ischemia (by 160%) and smallest if 15 min (by 40%) of ischemia was used. In comparison to the hippocampus, the activity of SOD in CSF increased equally after all intervals of ischemia. Activities of total SOD and CuZn-SOD after 10 min of ischemia in the hippocampus were significantly increased only after 5 and 24 h of reperfusion but in CSF they were increased after all examined intervals of reperfusion. The activity of CAT was significantly increased in the hippocampus after 5 (by 260%), 10 and 15 min (by 100%) of ischemia. CAT activity in CSF was increased equally after all intervals of ischemia (by 200%). Ischemic attack causes a rapid response in hippocampal tissue as well as in the CSF, represented by an increase in the activity of endogenous antioxidant enzymes SOD and CAT.

Vascular adhesion protein-1 plays an important role in postischemic inflammation and neuropathology in diabetic, estrogen-treated ovariectomized female rats subjected to transient forebrain ischemia

Endothelial vascular adhesion protein-1 (VAP-1) facilitates leukocyte adhesion and infiltration. This relates partly to the function of VAP-1 as a semicarbazide-sensitive amine oxidase (SSAO). We examined the effects of VAP-1/SSAO inhibition [via LJP-1207 (N'-(2-phenyl-allyl)-hydrazine hydrochloride)] on pial venular leukocyte adhesion and infiltration (at 2-10 h of reperfusion) and neuropathology (at 72 h of reperfusion) after transient forebrain ischemia (TFI). A model associated with increased postischemic inflammation was used-i.e., diabetic ovariectomized (OVX) female rats given chronic estrogen replacement therapy (ERT). We compared rats treated, either at the onset or at 6 h of reperfusion, with saline or LJP-1207. Additional rats, rendered neutropenic 24 h before TFI, were studied. In saline-treated controls, intravascular accumulation of adherent leukocytes gradually increased, reaching 15 to 20% of the venular area, at which point neutrophil infiltration commenced (at approximately 6 h). In the rats given LJP-1207 at the onset of reperfusion, limited neutrophil adhesion ( approximately 5% maximum) and no infiltration were observed. These results generally paralleled those in neutropenic rats. In rats treated at 6 h of reperfusion, the pattern of neutrophil adhesion was similar to that of the saline-treated group up to 6 h, but further infiltration was essentially prevented. Neurologic outcomes and histopathology were similar to one another in the LJP-1207-treated and neutropenic groups and significantly improved over those in saline-treated controls. Thus, VAP-1-mediated post-TFI leukocyte adhesion/infiltration in diabetic OVX females given chronic ERT contributes substantially to neuropathology. One implication is that specifically preventing leukocyte infiltration provides a substantial measure of neuroprotection. This could explain the finding of LJP-1207 having at least a 6-h therapeutic window in this model.