Cerebrospinal fluid volume as an early radiological factor for clinical course prediction after aneurysmal subarachnoid hemorrhage. A pilot study.

BACKGROUND: The pathological mechanisms following aneurysmal subarachnoid hemorrhage (SAH) are poorly understood. Limited clinical evidence exists on the association between cerebrospinal fluid (CSF) volume and the risk of delayed cerebral ischemia (DCI) or cerebral vasospasm (CV). In this study, we raised the hypothesis that the amount of CSF or its ratio to hemorrhage blood volume, as determined from non-contrast Computed Tomography (NCCT) images taken on admission, could be a significant predictor for CV and DCI. METHODS: The pilot study included a retrospective analysis of NCCT scans of 49 SAH patients taken shortly after an aneurysm rupture (33 males, 16 females, mean age 56.4 ± 15 years). The SynthStrip and Slicer3D software tools were used to extract radiological factors - CSF, brain, and hemorrhage volumes from the NCCT images. The "pure" CSF volume (VCSF) was estimated in the range of [-15, 15] Hounsfield units (HU). RESULTS: VCSF was negatively associated with the risk of CV occurrence (p = 0.0049) and DCI (p = 0.0069), but was not associated with patients' outcomes. The hemorrhage volume (VSAH) was positively associated with an unfavorable outcome (p = 0.0032) but was not associated with CV/DCI. The ratio VSAH/VCSF was positively associated with, both, DCI (p = 0.031) and unfavorable outcome (p = 0.002). The CSF volume normalized by the brain volume showed the highest characteristics for DCI prediction (AUC = 0.791, sensitivity = 0.80, specificity = 0.812) and CV prediction (AUC = 0.769, sensitivity = 0.812, specificity = 0.70). CONCLUSION: It was demonstrated that "pure" CSF volume retrieved from the initial NCCT images of SAH patients (including CV, Non-CV, DCI, Non-DCI groups) is a more significant predictor of DCI and CV compared to other routinely used radiological biomarkers. VCSF could be used to predict clinical course as well as to personalize the management of SAH patients. Larger multicenter clinical trials should be performed to test the added value of the proposed methodology.

Evaluation of CSF 8-iso-prostaglandin F2α and erythrocyte anisocytosis as prognostic biomarkers for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

Delayed cerebral ischemia (DCI) is a serious, life-threatening, complication affecting patients who have survived the initial bleeding from a ruptured intracranial aneurysm. Due to the challenging diagnosis, potential DCI prognostic markers should be of value in clinical practice. According to recent reports isoprostanes and red blood cell distribution (RDW) showed to be promising in this respect. We conducted a prospective study of 27 aSAH patients and control group (n = 8). All patients from the study group were treated within the first day of the initial bleeding. We collected data regarding clinical status and results of biochemical, and radiological examinations. We measured cerebrospinal fluid (CSF) concentration of 8-iso-prostaglandin F2α (F2-IsoP) and RDW on days 1, 3, and 5. Both CSF F2-IsoP level and RDW-SD measured on day 1 were significant predictors of DCI. The receiver operating characteristics curve for DCI prediction based on the multivariate model yielded an area under the curve of 0.924 (95% CI 0.824-1.000, p < 0.001). In our study, the model based on the combination of RDW and the level of isoprostanes in CSF on the first day after the initial bleeding showed a prognostic value for DCI prediction. Further studies are required to validate this observation.

Mitochondrial dysfunction associated with autophagy and mitophagy in cerebrospinal fluid cells of patients with delayed cerebral ischemia following subarachnoid hemorrhage.

Decreased mitochondrial membrane potential in cerebrospinal fluid (CSF) was observed in patients with subarachnoid hemorrhage (SAH) accompanied by delayed cerebral ischemia (DCI). However, whether abnormal mechanisms of mitochondria are associated with the development of DCI has not been reported yet. Under cerebral ischemia, mitochondria can transfer into the extracellular space. Mitochondrial dysfunction can aggravate neurologic complications. The objective of this study was to evaluate whether mitochondrial dysfunction might be associated with autophagy and mitophagy in CSF cells to provide possible insight into DCI pathogenesis. CSF samples were collected from 56 SAH patients (DCI, n = 21; and non-DCI, n = 35). We analyzed CSF cells using autophagy and mitophagy markers (DAPK1, BNIP3L, BAX, PINK1, ULK1, and NDP52) via qRT-PCR and western blotting of proteins (BECN1, LC3, and p62). Confocal microscopy and immunogold staining were performed to demonstrate the differentially expression of markers within dysfunctional mitochondria. Significant induction of autophagic flux with accumulation of autophagic vacuoles, increased expression of BECN1, LC3-II, and p62 degradation were observed during DCI. Compared to non-DCI patients, DCI patients showed significantly increased mRNA expression levels (2-ΔCt) of DAPK1, BNIP3L, and PINK1, but not BAX, ULK1, or NDP52. Multivariable logistic regression analysis revealed that Hunt and Hess grade ≥ IV (p = 0.023), DAPK1 (p = 0.003), and BNIP3L (p = 0.039) were related to DCI. Increased mitochondrial dysfunction associated with autophagy and mitophagy could play an important role in DCI pathogenesis.

Inflammatory profile in a canine model of hypothermic circulatory arrest.

BACKGROUND: Hypothermic circulatory arrest (HCA) is a technique used for complex repair of the aorta, but it can be associated with neurologic morbidity. To better understand the molecular changes that underlie ischemic brain injury, we assessed gene expression and cytokine/chemokine polypeptide concentration in brain tissue and cerebrospinal fluid (CSF) of canines that underwent two hours of HCA. MATERIALS AND METHODS: Adult male canines were cannulated peripherally for cardiopulmonary bypass, cooled to 18°C, and arrested for two hours. Animals were euthanized two, eight, or 24 hours post-HCA (n = 8 per group), and their brains were compared to brains from eight normal canines, using gene expression microarray analysis, cytokine assay, and histopathology. RESULTS: Two to eight hours after HCA, pro-inflammatory cytokine mRNAs increased markedly, and gene expression was enriched within signaling pathways related to neuroinflammation or ischemic injury. Concentrations of pro-inflammatory cytokine polypeptides IL-6, IL-8, IL-1ß, and CCL2 were very low in normal canine brain, whereas anti-inflammatory IL-10 and TGF-ß1 were expressed at moderate levels. Pro-inflammatory cytokine concentrations rose robustly in cerebral tissue and CSF after HCA. IL-6 and IL-8 peaked at eight hours and declined at 24 hours, while IL-1ß and CCL2 remained elevated. Concentrations of anti-inflammatory IL-10 and TGF-ß1 were maintained after HCA, with a significant increase in TGF-ß1 at 24 hours. CONCLUSIONS: These cytokines represent potential diagnostic markers for ischemic neurologic injury that could be used to assess neurologic injury in patients undergoing HCA. The cellular mechanisms underlying this pro-inflammatory, ischemic-induced injury represent potential targets for neuroprotection in the future.

Interleukin 6 in cerebrospinal fluid is a biomarker for delayed cerebral ischemia (DCI) related infarctions after aneurysmal subarachnoid hemorrhage.

Interleukin 6 (IL-6) is a prominent proinflammatory cytokine and has been discussed as a potential biomarker for delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage. In the present study we have analyzed the time course of serum and cerebrospinal fluid (CSF) IL-6 levels in 82 patients with severe aneurysmal subarachnoid hemorrhage (SAH) requiring external ventricular drains in correlation to angiographic vasospasm, delayed cerebral ischemia, secondary infarctions and other clinical parameters. We observed much higher daily mean IL-6 levels (but also large interindividual variations) in the CSF than the serum of the patients with a peak between days 4 and 14 including a maximum on day 5 after SAH. Individual CSF peak levels correlated significantly with DCI (mean day 4-14 peak, DCI: 26,291 ± 24,159 pg/ml vs. no DCI: 16,184 ± 13,163 pg/ml; P = 0.023). Importantly, CSF IL-6 levels differed significantly between cases with DCI and infarctions and patients with DCI and no infarction (mean day 4-14 peak, DCI with infarction: 37,209 ± 26,951 pg/ml vs. DCI, no infarction: 15,123 ± 11,239 pg/ml; P = 0.003), while findings in the latter patient group were similar to cases with no vasospasm (mean day 4-14 peak, DCI, no infarction: 15,123 ± 11,239 vs. no DCI: 15,840 ± 12,979; P = 0.873). Together, these data support a potential role for elevated CSF IL-6 levels as a biomarker for DCI with infarction rather than for DCI in general. This fits well with a growing body of evidence linking neuroinflammation to ischemia and infarction, but (together with the large interindividual variations observed) limits the diagnostic usefulness of CSF IL-6 levels in SAH patients.

Impact of brain volume and intracranial cerebrospinal fluid volume on the clinical outcome in endovascularly treated stroke patients.

PURPOSE: Previously, brain volume (BV) and intracranial cerebrospinal fluid volume (CSFV) have been investigated regarding clinical outcomes of subgroups of ischemic stroke patients. This study aimed to examine if the preexisting, preischemic BV and CSFV have an impact on good functional outcome and mortality in acute ischemic stroke (AIS) patients treated with mechanical thrombectomy (MT). METHODS: Preischemic BV, CSFV, and CSFV/Total intracranial volume (TICV)-ratio were calculated with a fully automated segmentation platform. Univariate and multivariate analyses were used to study associations. RESULTS: In this retrospective study 107 subsequent AIS patients of a prospective database were included. The segmentation results of the fully automated algorithm based on non-contrast computerized tomography scans (NCCT) correlated significantly with the segmentation results obtained from 3D T1 weighted magnetic resonance images (P < 0.001). In the univariate analysis a preexisting BV (P < 0.001), preexisting CSFV (P = 0.009), and the ratio CSFV/total intracranial volume (P < 0.001) each significantly correlated with good functional outcome and mortality. However, in the multivariate regression analysis, also correcting for patient age, none of these volumes remained to correlate with these outcome parameters. CONCLUSION: In summary, an association of BV, CSFV, and the CSFV/TICV-ratio with good functional outcome and mortality in AIS treated with MT could not be established. A fully automated segmentation algorithm based on NCCT was successfully developed in-house for calculating the volumes of interest.

Cerebrospinal Fluid Biomarkers to Differentiate Idiopathic Normal Pressure Hydrocephalus from Subcortical Ischemic Vascular Disease.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) remains a challenge to differentiate from subcortical ischemic vascular disease (SIVD). Despite major research efforts, the cerebrospinal fluid (CSF) biomarker profiles of the two diseases are still not known in detail. OBJECTIVE: To determine if novel CSF biomarkers, neurofilament light (NFL) reflecting axonal damage, the synaptic protein neurogranin (NG), and the astroglial marker chitinase-3-like protein 1 (YKL-40), and the core Alzheimer's disease (AD) biomarkers, amyloid-ß 42 (Aß42), total tau (t-tau), phosphorylated tau (p-tau), can differentiate iNPH from SIVD. Patients with AD and healthy controls (HC) were included for comparison purposes. METHODS: Patients with iNPH (n = 28), SIVD (n = 30), AD (n = 57), and HC (n = 33) were retrospectively included from the Danish Dementia Biobank. All patients with iNPH had effect of shunt surgery with a follow-up period of 4 to 69 months. CSF biomarkers were measured using immunoassays. RESULTS: Lower levels of NFL, NG, Aß42, and t-tau were found in patients with iNPH versus SIVD, while YKL-40 and p-tau were similar in the two diseases. NFL and Aß42 were the most reliable biomarkers to differentiate iNPH from SIVD with an area under the curve (AUC) on 0.82 and 0.80, respectively. Combining NFL with Aß42, t-tau, and p-tau resulted in an AUC of 0.90, which was equivalent to the diagnostic accuracy of all six biomarkers combined. CONCLUSION: An addition of NFL to the CSF panel of Aß42, t-tau, and p-tau may improve the differentiation of iNPH from SIVD.

Central Nervous System Fungal Infection-Related Stroke: A Descriptive Study of Mold and Yeast-Associated Ischemic Stroke.

OBJECTIVE: Central nervous system (CNS) ischemic events caused by fungal infections are rare, and clinical characteristics of these ischemic events are largely unknown. The objective of this manuscript is to highlight characteristics of fungal-related strokes and describe possible mechanistic differences between CNS mold and yeast infection-related strokes. METHODS: We report a single-center retrospective case series of all adult patients who presented with concurrent CNS fungal infection and stroke between 2010 and 2018. Patients believed to have a stroke etiology due to cardioembolic, atheroembolic, or strokes nontemporally associated with a CNS fungal infection and those with incomplete stroke workups were excluded from analysis. RESULTS: Fourteen patients were identified with ischemic stroke and concurrent CNS fungal infection without other known ischemic stroke etiology. Eight patients had a CNS yeast infection, and 6 had a CNS mold infection. All patients presented with recurrent or progressive stroke symptoms. Six patients were immune-compromised. Four patients admitted to intravenous drug use. All yeast infections were identified by cerebrospinal fluid culture or immunologic studies while all but one of the mold infections required identification by tissue biopsy. Leptomeningeal enhancement was only associated with CNS yeast infections, while basal ganglia stroke was only associated with CNS mold infections. CONCLUSION: Ischemic stroke secondary to CNS fungal infections should be considered in patients with recurrent or progressive cryptogenic stroke, regardless of immune status and cerebrospinal fluid profile. CNS yeast and mold infections have slightly different stroke and laboratory characteristics and should have a distinct diagnostic method. Depending on clinical suspicion, a thorough diagnostic approach including spinal fluid analysis and biopsy should be considered.

Lactate and Lactate Dehydrogenase in Cistern as Biomarkers of Early Brain Injury and Delayed Cerebral Ischemia of Subarachnoid Hemorrhage.

OBJECTIVE: The pathophysiology of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) has not been fully evaluated. The aim of this study was to evaluate the dynamics of lactate and lactate dehydrogenase (LDH) in carotid cisternal cerebrospinal fluid (CSF), and to discuss their effectiveness as markers of early brain injury (EBI) and DCI following aSAH. PATIENTS AND METHODS: Among 91 consecutive aSAH patients treated between January 2012 and March 2019 at National Hospital Organization Beppu Medical Center, 19 patients (20.9%) were eligible for this retrospective study. Concentrations of lactate and LDH in carotid cisternal CSF within 14 days after onset of aSAH were evaluated. RESULTS: Six of the 19 patients (31.6%) had a history of DCI. Both lactate and LDH levels in carotid cisternal CSF were significantly higher in the DCI group than in the non-DCI group on postbleeding day (PBD) 1-2, 3-4, and 5-6. Interestingly, neither lactate nor LDH levels in blood differed significantly between DCI and non-DCI groups on PBD 1-2. CONCLUSIONS: Lactate and LDH concentrations in carotid cisternal CSF may vividly reflect the EBI and may thus represent predictive biomarkers of DCI following aSAH.

Change in CSF Dynamics Responsible for ICP Elevation After Ischemic Stroke in Rats: a New Mechanism for Unexplained END?

It has been proposed that intracranial pressure (ICP) elevation and collateral failure are responsible for unexplained early neurological deterioration (END) in stroke. The study's aims were to investigate whether cerebral spinal fluid (CSF) dynamics, rather than edema, are responsible for elevation of ICP after ischemic stroke. Permanent middle cerebral artery occlusion (pMCAO) was induced with an intraluminal filament. At 24 h after stroke, baseline ICP was measured and CSF dynamics were probed via a steady-state infusion method. Diffusion-weighted imaging (DWI) and T2-weighted magnetic resonance imaging were performed to define cerebral ischemic damage and the volume of brain swelling. We found that the pMCAO group exhibited a significant increase in CSF outflow resistance (2.27 ± 0.15 mmHg µL-1 min) compared with the sham group (0.93 ± 0.06 mmHg µL-1 min, p = 0.002). There was no correlation between mean ICP at 24 h post-pMCAO and edema (r2 = - 0.03, p = 0.5) or infarct volumes (r2 = 0.09, p = 0.5). However, for the first time, we found a significant correlation between the baseline ICP at 24 h post-stroke and the value of CSF outflow resistance. Results show that CSF outflow resistance, rather than edema, was the mechanism responsible for ICP elevation following ischemic stroke. This challenges current concepts and suggests the possibility that intracranial hypertension may be occurring undetected in a much wider range of stroke patients than is currently considered to be the case. In addition, this further supports the hypothesis that unexplained early neurological deterioration is the result of elevated ICP, leading to reduced collateral flow and cerebral perfusion.

Would Colloidal Gold Nanocarriers Present An Effective Diagnosis Or Treatment For Ischemic Stroke?

INTRODUCTION: This study was conducted to evaluate OX26-PEG-coated gold nanoparticles (GNPs) (OX26@GNPs) as a novel targeted nanoparticulate system on cell survival after ischemic stroke. MATERIALS AND METHODS: Dynamic light scattering (DLS), zeta sizer, and transmission electron microscopy (TEM) were performed to characterize the OX26@GNPs. The effect of OX26@GNPs on infarct volume, neuronal loss, and necroptosis was evaluated 24 h after reperfusion using 2, 3,5-Triphenyltetrazolium chloride (TTC) staining, Nissl staining and Western blot assay, respectively. RESULTS: Conjugation of OX26-PEG to the surface of the 25 nm colloidal gold particles increased their size to 32±2 nm, while a zeta potential change of -40.4 to 3.40 mV remarkably increased the stability of the nanoparticles. Most importantly, OX26@GNPs significantly increased the infarcted brain tissue, while bare GNPs and PEGylated GNPs had no effect on the infarct volume. However, our results indicated an extension of necroptotic cell death, followed by cell membrane damage. CONCLUSION: Collectively, our results showed that the presently formulated OX26@GNPs are not suitable nanocarriers nor contrast agents under oxidative stress for the diagnosis and treatment of ischemic stroke. Moreover, our findings suggest that the cytotoxicity of GNPs in the brain is significantly associated with their surface charge.

Cerebrospinal Fluid Concentrations of Nimodipine Correlate With Long-term Outcome in Aneurysmal Subarachnoid Hemorrhage: Pilot Study.

OBJECTIVES: The aim was to evaluate plasma and cerebrospinal fluid (CSF) nimodipine concentrations in patients with aneurysmal subarachnoid hemorrhage and their correlation with clinical outcome. METHODS: Nimodipine infusion was started at 1 mg/h and increased up to 2 mg/h and continued up to 21 days in surviving patients. Arterial and CSF samples were collected at least after 24 hours of stable nimodipine dosing. Delayed cerebral ischemia and vasospasm were documented by new neurological deficits and neuroimaging. The clinical outcome was assessed at 9 months by the modified Rankin scale. RESULTS: Twenty-three patients were enrolled. Nimodipine dose was 13 to 38 µg/kg per hour. Nimodipine arterial and CSF concentrations were 24.9 to 71.8 ng/mL and 37 to 530 pg/mL, respectively. Dose did not correlate with arterial or CSF concentrations. Arterial concentrations did not correlate with corresponding CSF concentrations. Doses and arterial concentrations did not correlate with the clinical outcome and were not associated with the occurrence of delayed cerebral ischemia. However, patients with no significant disability after 9 months of hemorrhage showed significantly higher CSF nimodipine concentrations (P = 0.015) and CSF-to-plasma ratios (P = 0.011) compared with patients who showed some degree of disability or who died. CONCLUSIONS: Cerebrospinal fluid nimodipine concentrations measured during hospital drug infusion showed a correlation with long-term clinical outcome in patients with aneurysmal subarachnoid hemorrhage. These very preliminary data suggest that CSF concentrations monitoring may have some value in managing these patients.

A Metabonomics Investigation into the Therapeutic Effects of BuChang NaoXinTong Capsules on Reversing the Amino Acid-Protein Interaction Network of Cerebral Ischemia.

BACKGROUND: Amino acids (AAs) in cerebrospinal fluid (CSF) play a pivotal role in cerebral ischemia (CI). BuChang NaoXinTong Capsules (BNC) are widely prescribed in Chinese medicine for the treatment of cerebrovascular and cardiovascular diseases. METHODS: In order to investigate the therapeutic effects and pharmacological mechanisms of BNC on reversing CI from a system level, an amino acid-protein interaction imbalanced network of CI containing metabolites of AAs, key regulatory enzymes, and proteins was constructed for the first time. Furthermore, a novel method for detecting the ten AAs in CSF was developed by UPLC-QQQ-MS in an effort to validate the imbalanced networks and the therapeutic effects of BNC via analysis of metabolites. RESULTS: Based on a middle cerebral artery occlusion (MCAO) rat model, the dynamic levels of amino acids in CSF 3, 6, 12, and 24 h after MCAO were analyzed. Up to 24 h, the accumulated nine AA biomarkers were found to significantly change in the MCAO group compared to the sham group and exhibited an obvious tendency for returning to baseline values after BNC treatment. In addition, based on the imbalanced network of CI, four key enzymes that regulate the generation of BNC-mediated AA biomarkers were selected and validated using an enzyme-linked immunosorbent assay and western blotting. Finally, aromatic-L-amino-acid decarboxylase (AADC) was found to be one of the putative targets for BNC-mediated protection against CI. CONCLUSION: This study provides new strategies to explore the mechanism of cerebral ischemia and help discover the potential mechanism of BNC.

Efecto de la isquemia cerebral permanente sobre la fascia dentada del hipocampo en gerbils / Effect of the permanent cerebral ischemia on the dentate fascia of the gerbils hypocampus

Se realizó un estudio prospectivo y experimental, a partir de la inducción de un trauma isquémico cerebral permanente, mediante sección de la carótida derecha, en 24 gerbils de Mongolia, procedentes del Centro Nacional para la Producción de Animales de Laboratorio, con vistas a identificar los posibles cambios en las poblaciones de neuronas de la fascia dentada del hipocampo durante la isquemia. Los resultados revelaron que la isquemia cerebral permanente produce destrucción progresiva y total de las neuronas en la fascia dentada durante las primeras 72 horas del proceso isquémico y muestra 3 momentos durante su evolución con características específicas para cada uno, así como cambios en las proporciones entre las neuronas en proceso de muerte celular, las aparentemente sanas y aquellas con diferentes cantidades de nucléolos en la zona dañada por el proceso isquémico.

A prospective and experimental study was carried out, from the induction of a permanent cerebral ischemic trauma, by means of a cut to the right carotid vein, in 24 gerbils from Mongolia, obtained from the National Center for Laboratory Animals Production, with the aim of identifying the possible changes in the neurons populations of the hypocampus dentate fascia during ischemia. The results revealed that the permanent cerebral ischemia produces progressive and total destruction of the neurons in the dentate fascia during the first 72 hours of the ischemic process and it shows 3 moments during its course, each of them with specific characteristics, as well as changes in the proportions among the neurons during cellular death, those apparently healthy and those with different quantities of nucleolous in the area damaged by the ischemic process.

Combined proteomic and metabolomic analyses of cerebrospinal fluid from mice with ischemic stroke reveals the effects of a Buyang Huanwu decoction in neurodegenerative disease.

Ischemic stroke is one of the most common causes of death worldwide and is a major cause of acquired disability in adults. However, there is still a need for an effective drug for its treatment. Buyang Huanwu decoction (BHD), a traditional Chinese medicine (TCM) prescription, has long been used clinically to aid neurological recovery after stroke. To establish potential clinical indicators of BHD efficacy in stroke treatment and prognosis, we conducted a combined proteomic and metabolomic analysis of cerebrospinal fluid (CSF) samples in a mouse stroke model. CSF samples were obtained from male mice with acute ischemic stroke induced by middle cerebral ischemic/reperfusion (CI/R) injury, some of which were then treated with BHD. Label-free quantitative proteomics was conducted using nano-LC-MS/MS on an LTQ Orbitrap mass and metabolomic analysis was performed using nanoprobe NMR and UHPLC-QTOF-MS. The results showed that several proteins and metabolites were present at significantly different concentrations in the CSF samples from mice with CI/R alone and those treated with BHD. These belonged to pathways related to energy demand, inflammatory signaling, cytoskeletal regulation, Wnt signaling, and neuroprotection against neurodegenerative diseases. In conclusion, our in silico data suggest that BHD treatment is not only protective but can also ameliorate defects in pathways affected by neurological disorders. These data shed light on the mechanism whereby BHD may be effective in the treatment and prevention of stroke-related neurodegenerative disease.

Immunophenotyping of cerebrospinal fluid cells in ischaemic stroke.

BACKGROUND AND PURPOSE: Post-ischaemic immune cell invasion into the brain is well characterized in animal stroke models and contributes to neuronal damage. Therefore, it represents a promising therapeutic target. Cerebrospinal fluid (CSF) is easily accessible and may reflect cellular events within the parenchyma. However, comprehensive studies on CSF immune cells in patients with stroke are lacking. METHODS: In a retrospective cohort study, we performed extensive immune-cell profiling in CSF and peripheral blood of patients with acute ischaemic stroke and healthy controls. In patients with stroke, infarct size was quantified on follow-up imaging. RESULTS: Overall, 90 patients with ischaemic stroke and 22 controls were included in our study. After stroke, the total protein was increased (537.3 vs. 353.2 mg/L, P = 0.008) and the mean total white cell count was slightly but non-significantly elevated (1.76 vs. 0.50 cells/µL, P = 0.059). Proportions of CSF lymphocytes, monocytes and granulocytes and their respective subsets did not differ between patients with stroke and controls. In addition, there were no associations between proportions of major leukocyte subsets in CSF and the time from symptom onset to CSF sampling, infarct size or infarct localization. CONCLUSIONS: Ischaemic stroke induces only a very slight increase of CSF immune cells without changes in the composition of immune cell subsets, thus indicating that parenchymal inflammation is not sufficiently reflected in the CSF. Our findings suggest that CSF is not a major invasion route for immune cells and that CSF cell analyses are not suitable as biomarkers to guide future immune therapies for stroke.

Neurofilament changes in serum and cerebrospinal fluid after acute ischemic stroke.

BACKGROUND: Neurofilament light (NFL) is a well-validated biomarker for neuronal injury and neurodegeneration. Increased cerebrospinal fluid (CSF) levels have been shown after stroke, as well as in patients with a broad range of neurodegenerative and neuroinflammatory diseases. Neurofilament heavy (NFH) belongs to the same family of structural proteins but it is less extensively studied. The potential of phosphorylated NFH (pNFH) as a stroke biomarker and for the prediction of clinical outcome is unknown. In this study, we aimed to examine the temporal pattern of NFL and pNFH concentrations in serum and CSF after acute ischemic stroke. MATERIALS AND METHODS: A quantitative Enzyme-Linked ImmunoSorbent Assay (ELISA) for pNFH was developed and tested on CSF and serum samples. NFL and pNFH were analysed in serum and CSF of acute ischemic stroke patients, who were followed over time (Day 0-1, Day 2-3, Day 7-9, three weeks, and 3-5 months after stroke). RESULTS: NFL and pNFH concentrations in serum and CSF increased after stroke, peaked during the 3rd week, and then decreased back to almost baseline levels at 3-5 months. CSF-NFL and serum-NFL correlated to the outcome measured by Barthel Index after 3-5 months, whilst no such association was seen for pNFH. DISCUSSION: These findings suggest that NFL and pNFH in both CSF and serum reflect the temporal pattern of the post ischemic axonal injury and that this process does not seem to progress after 3-5 months. CONCLUSION: NFL and pNFH in CSF and serum are promising biomarkers for axonal injury following stroke. Further studies in larger populations are needed to fully understand the progression of the neuronal damage after acute ischemic stroke and to evaluate if these biomarkers can provide additive information and how they relate to outcome.

Preconditioning in the Rhesus Macaque Induces a Proteomic Signature Following Cerebral Ischemia that Is Associated with Neuroprotection.

Each year, thousands of patients are at risk of cerebral ischemic injury, due to iatrogenic responses to surgical procedures. Prophylactic treatment of these patients as standard care could minimize potential neurological complications. We have shown that protection of brain tissue, in a non-human primate model of cerebral ischemic injury, is possible through pharmacological preconditioning using the immune activator D192935. We postulate that preconditioning with D192935 results in neuroprotective reprogramming that is evident in the brain following experimentally induced cerebral ischemia. We performed quantitative proteomic analysis of cerebral spinal fluid (CSF) collected post-stroke from our previously published efficacy study to determine whether CSF protein profiles correlated with induced protection. Four groups of animals were examined: naïve animals (no treatment or stroke); animals treated with vehicle prior to stroke; D192935 treated and stroked animals, further delineated into two groups, ones that were protected (small infarcts) and those that were not protected (large infarcts). We found that distinct protein clusters defined the protected and non-protected animal groups, with a 16-member cluster of proteins induced exclusively in D192935 protected animals. Seventy percent of the proteins induced in the protected animals have functions that would enhance neuroprotection and tissue repair, including several members associated with M2 macrophages, a macrophage phenotype shown to contribute to neuroprotection and repair during ischemic injury. These studies highlight the translational importance of CSF biomarkers in defining mechanism and monitoring responses to treatment in development of stroke therapeutics.

Cell-Free Oxyhemoglobin in Cerebrospinal Fluid After Aneurysmal Subarachnoid Hemorrhage: Biomarker and Potential Therapeutic Target.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is often complicated by the occurrence of delayed ischemic neurologic deficits (DIND), which impairs the clinical outcome of patients. The release of oxyhemoglobin (oxyHb) from lysing erythrocytes into cerebrospinal fluid (CSF) may critically contribute to the development of DIND. METHODS: Ventricular CSF of 18 high-grade (Fisher 3 and 4) aSAH patients was sampled daily from external ventricular drains between days 0 and 14 after bleeding. CSF was spectrophotometrically analyzed with precise quantification of cell-free oxyHb levels. RESULTS: OxyHb levels in CSF showed a delayed peak reaching the highest levels in the high-risk period for developing of DIND between days 3 and 14 after aneurysm rupture. Patients with DIND had a significantly higher cumulative oxyHb exposure within the first week after bleeding. CONCLUSIONS: OxyHb levels in CSF may be useful as a biomarker to predict DIND in aSAH patients. The contribution of oxyHb in CSF to the pathogenesis of DIND should be further investigated as a potential therapeutic target.