Admission C – reactive protein after acute ischemic stroke is associated with stroke severity and mortality: The 'Bergen stroke study'

Background

There is growing evidence that inflammation plays an important role in atherogenesis. Previous studies show that C-reactive protein (CRP), an inflammatory marker, is associated with stroke outcomes and future vascular events. It is not clear whether this is due a direct dose-response effect or rather an epiphenomenon. We studied the effect of CRP measured within 24 hours after stroke onset on functional outcome, mortality and future vascular events.

Methods

We prospectively studied 498 patients with ischemic stroke who were admitted within 24 hours after the onset of symptoms. CRP and NIH stroke scale (NIHSS) were measured at the time of admission. Short-term functional outcome was measured by modified Rankin scale (mRS) and Barthel ADL index (BI) 7 days after admission. Patients were followed for up to 2.5 years for long-term mortality and future vascular events data.

Results

The median CRP at admission was 3 mg/L. High CRP was associated with high NIHSS (p = 0.01) and high long-term mortality (p < 0.0001). After adjusting for confounding variables, high CRP remained to be associated with high NIHSS (p = 0.02) and high long-term mortality (p = 0.002). High CRP was associated with poor short-term functional outcomes (mRS > 3; BI < 95) (p = 0.01; p = 0.03). However, the association was not significant after adjusting for confounding variables including stroke severity (p = 0.98; p = 0.88). High CRP was not associated with future vascular events (p = 0.98).

Conclusion

Admission CRP is associated with stroke severity and long-term mortality when measured at least 24 hours after onset. There is a crude association between high CRP and short-term functional outcome which is likely secondary to stroke severity. CRP is an independent predictor of long-term mortality after ischemic stroke.     

Astrocytes and stroke: networking for survival?

Astrocytes are now known to be involved in the most integrated functions of the central nervous system. These functions are not only necessary for the normally working brain but are also critically involved in many pathological conditions, including stroke. Astrocytes may contribute to damage by propagating spreading depression or by sending proapoptotic signals to otherwise healthy tissue via gap junction channels. Astrocytes may also inhibit regeneration by participating in formation of the glial scar. On the other hand, astrocytes are important in neuronal antioxidant defense and secrete growth factors, which probably provide neuroprotection in the acute phase, as well as promoting neurogenesis and regeneration in the chronic phase after injury. A detailed understanding of the astrocytic response, as well as the timing and location of the changes, is necessary to develop effective treatment strategies for stroke patients.     

How much physical therapy for patients with stroke?

The use of physiotherapy, occupational therapy, and speech therapy for patients with stroke was investigated, and the three treatments were compared. Out of 135 patients with stroke surviving at two weeks, 107 received physiotherapy, but only 35 received occupational therapy and 19 speech therapy. Those who received most physiotherapy were the most severely disabled and had the worst prognosis, and, although almost no recovery occurred after six months, 30 patients continued with treatment beyond this time. Stiff and painful shoulders were present in 21 of the patients by two weeks and had developed in a further 37 by one year. Physiotherapy did not prevent this. The objectives of physiotherapy for patients with stroke need careful definition, with emphasis on treatment in the early months. Alternative treatment, possibly carried out by volunteers or more simply trained personnel, merits further consideration.     

ALDH2, a novel protector against stroke?

In a recent paper published in Cell Research, an association between expression of mitochondrial aldehyde dehydrogenase (ALDH2), a mitochondrial chaperon expressed in the brain, and the prevalence of stroke is revealed. This finding indicates that ALDH2 may serve as a potential endogenous neuroprotective target and a promising therapeutic strategy for the management of stroke.Stroke is one of the leading causes of death and a major reason of adult chronic disability as well as age-related cognitive decline and dementia¹. Ischemic stroke represents > 80% of all stroke incidences with the remaining 20% due to primary hemorrhage. Proper management of the conventional risk factors for stroke, such as high blood pressure, elevated blood cholesterol, cigarette smoking, carotid stenosis, diabetes mellitus and heart failure, may reduce the incidence of stroke only to a certain degree, suggesting the existence of undiscovered or undefined risk factors^1,2. The unidentified risk factors for stroke, in conjunction with unsatisfactory control of known risk factors (e.g., high cholesterol and hypertension), may explain the intimate clinical challenge or failure for stroke management. To this end, identification of novel risk factors may hold promises in the development of strategies for prevention and treatment of stroke. Ample evidence has implicated the importance of genetic predisposition in the onset and progression of stroke². More recently, genome-wide association study (GWAS) approach has transformed the genetics of many complex chronic diseases and is just beginning to impact the field of stroke³. Genetic variants predisposing to ischemic stroke have been revealed by GWAS, such as two loci associated with atrial fibrillation (PITX2 and ZFHX3) linked to cardioembolic stroke and a locus on chromosome 9p21 tied to large-vessel stroke^1,4,5. Nonetheless, the precise contribution of genetics to the etiology of stroke, in particular various stroke subtypes, remains somewhat elusive. Gene candidates that have been identified to be associated with stoke warrant further validation in a large independent data set to consolidate their causative role in the pathogenesis of stroke.In a recent paper published in Cell Research, Guo and colleagues performed an unbiased proteomic examination and unveiled a unique role of deficiency in mitochondrial aldehyde dehydrogenase (ALDH2), the so-called “facial flash gene” responsible for detoxification of toxic aldehydes such as 4-hydroxy-2-nonenal (4-HNE), in the pathogenesis of stroke⁶. In their study, overexpression or activation of ALDH2 conferred neuroprotection through clearance of 4-HNE whereas ALDH2 knockdown mitigated the neuroprotective property of PKCɛ. The PKCɛ-ALDH2 pathway was shown to mediate neuroprotection offered by moderate ethanol intake. Serum 4-HNE levels were inversely correlated with lifespan and elevated plasma 4-HNE levels were observed for at least 6 months following stroke onset. Perhaps the most intriguing evidence is that much higher initial plasma 4-HNE levels were associated with development of stroke in an 8-year follow-up study. These findings favor a likely role of ALDH2 in the prevalence of stroke or stroke-prone subjects, and furthermore, its therapeutic potential as a target in the management of stroke (Figure 1).Open in a separate windowFigure 1Schematic diagram depicting the possible interplay between ischemic stroke and elevated serum 4-HNE levels. Serum 4-HNE levels positively correlates with stroke injury and remains elevated after stroke. Deficiency and activation of ALDH2 significantly accentuates and attenuates stroke-associated cerebral ischemia injury, respectively.ALDH2 is a human gene found on chromosome 12. All Caucasians are homozygous for ALDH2 while approximately 50% of Asians are heterozygous and possess only one normal copy of the ALDH2 gene and one mutant copy encoding an inactive mitochondrial isozyme⁷. A recent meta-analysis of GWAS identified a tight association between ALDH2 genetic mutation and elevated blood pressure, a known risk factor for stroke, in Asian decedents⁸. This is supported by the recent observation favoring a crucial role for ALDH2 in the regulation of cardiovascular homeostasis in diabetes, alcoholism, endoplasmic reticulum stress, arrhythmias and ischemia-reperfusion injury^9,10,11. Stroke is known to interrupt mitochondrial function and promote mitochondrial swelling and depolarization, leading to ultimate neuronal cell death¹². ALDH2 exerts a major role in aldehyde detoxification in mitochondria, and attenuates or ablates neuronal mitochondrial damage. Reactive aldehydes, including MDA, 4-HNE and 1-palmitoyl-2-oxovaleroyl phosphatidyl choline (POVPC), all of which are potential substrates for ALDH2, are elevated in ischemic stroke injury^1,12. Higher levels of 4-HNE and MDA were found in the serum of stroke-prone hypertensive rats compared with normotensive WKY rats⁶. Interestingly, only 4-HNE, but not MDA, was elevated in stroke-prone hypertensive rats compared with hypertensive rats, suggesting a role of 4-HNE as a possible biomarker for stroke.Given that approximately 40% of the East Asian population carries an ALDH2*2 mutant allele with dramatic reduction in ALDH2 enzymatic activity, the current observation suggest that ALDH2 mutation serves as a risk factor for stroke⁶. Unlike its reported role in the heart, little information is available for ALDH2 in the brain and cerebrovascular function. Like all animal studies, caution needs to be taken to translate experimental findings to a clinical setting. It is noteworthy that the animal outcome studies were performed at a relatively short period after stroke. A longer time window should be essential to the ultimate assessment of stroke injury. Further studies are needed to uncover the precise mechanism behind the regulation of ALDH2 in stroke.     

The stroke trial - can we predict clinical outcome of patients with ischemic stroke by measuring soluble cell adhesion molecules (CAM)?

BACKGROUND: Several studies have found that an increased concentration of haemostatic or inflammation markers was associated with worse prognosis in vascular disease. The inflammatory components in ischemic stroke are of current interest, and there is some experimental evidence that they may be linked. HYPOTHESIS: The study was performed to determine the association between the neurological clinical outcome and levels of cell adhesion molecules in the first four days of hospitalization in patients with acute ischemic event. METHODS: This prospective, pilot, case-controlled study examined the association between the clinical outcome and inflammatory markers within the first few days of hospitalization. The neurological evaluation was performed using the NIH score on admission and four days later, and levels of cell adhesion molecules were measured by ELISA methods on admission and four days later. RESULTS: Twenty three patients with an acute cerebral event (mean age 71 +/- 15 y, 12 women and 11 men) were examined neurologically on admission and four days later. Among 19 patients who improved, there was a significant decrease in the NIH neurological scale, from 3.8 +/- 3.2 to 1.3 +/- 1.8 (p = 0.01), which was accompanied by a significant decrease in the cell adhesion molecules that were measured (E-selectin, ICAM-1 and VCAM-1). Of the four patients who did not improve, their mean clinical NIH score was 10 +/- 4.6 and worsened or remained unchanged after four days of follow-up. In this group, we could not demonstrate a significant change in levels of cell adhesion molecules between days one and four. CONCLUSIONS: Patients who improved clinically within the first four days of hospitalization demonstrated a remarkable inhibition of all three cell adhesion molecules that were measured (E-selectin, ICAM-1, and VCAM-1). Patients who did not improve had more severe cerebral infarcts, a higher NIH score on admission (10 +/- 4.6), and no change was observed in levels of cell adhesion molecules during the follow-up period. Measuring cell adhesion molecule levels may predict objectively the clinical outcome in hospitalized patients with acute ischemic stroke.     

Lysyl oxidase polymorphisms and ischemic stroke—a case control study

Ischemic stroke is a common neurological disease and causes severe disability and death worldwide. Lysyl oxidase (LOX) plays a crucial role in the maintenance of extracellular matrix stability and may participate in vascular remodeling in the development of ischemic stroke. The objective of this study is to identify polymorphisms in LOX genes and investigate the association between LOX polymorphisms and the susceptibility to ischemic stroke in the Chinese population. Genomic DNA sequencing analysis was performed on all 7 exons and all exon/intron splice sites of lysyl oxidase and 850?bp upstream, including the predicted promoter region in 25 control subjects. The identified polymorphisms were then detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 702 ischemic stroke cases and 733 age-matched controls. Data were analyzed using the Chi-square test. Two polymorphisms in the LOX gene, 473G/A (rs1800449) and rs2278226, were observed in the Chinese population. Frequencies of LOX 473AA genotype and A allele were significantly higher in ischemic stroke patients than in controls (odds ration (OR)?=?1.76, 95?% confidence interval (CI) 1.16-2.67, P?=?0.007; and OR?=?1.33, 95?% CI 1.10-1.60, P?=?0.003). Also, the prevalence of AC haplotype was significantly increased in ischemic stroke cases (OR?=?1.32, 95?% CI 1.10-1.60, P?=?0.004). Our data suggest that the G473A polymorphism of LOX gene could be a new risk factor for ischemic stroke.     

Do nasogastric tubes worsen dysphagia in patients with acute stroke?

Background  

Early feeding via a nasogastric tube (NGT) is recommended as safe way of supplying nutrition in patients with acute dysphagic stroke. However, preliminary evidence suggests that NGTs themselves may interfere with swallowing physiology. In the present study we therefore investigated the impact of NGTs on swallowing function in acute stroke patients.     

Hypoxia-inducible factor 1 contributes to N-acetylcysteine’s protection in stroke

Stroke is a leading cause of adult morbidity and mortality with very limited treatment options. Evidence from preclinical models of ischemic stroke has demonstrated that the antioxidant N-acetylcysteine (NAC) effectively protects the brain from ischemic injury. Here, we evaluated a new pathway through which NAC exerted its neuroprotection in a transient cerebral ischemia animal model. Our results demonstrated that pretreatment with NAC increased protein levels of hypoxia-inducible factor-1α (HIF-1α), the regulatable subunit of HIF-1, and its target proteins erythropoietin (EPO) and glucose transporter (GLUT)-3, in the ipsilateral hemispheres of rodents subjected to 90 min middle cerebral artery occlusion (MCAO) and 24 h reperfusion. Interestingly, after NAC pretreatment and stroke, the contralateral hemisphere also demonstrated increased levels of HIF-1α, EPO, and GLUT-3, but to a lesser extent. Suppressing HIF-1 activity with two widely used pharmacological inhibitors, YC-1 and 2ME2, and specific knockout of neuronal HIF-1α abolished NAC’s neuroprotective effects. The results also showed that YC-1 and 2ME2 massively enlarged infarcts, indicating that their toxic effect was larger than just abolishing NAC's neuroprotective effects. Furthermore, we determined the mechanism of NAC-mediated HIF-1α induction. We observed that NAC pretreatment upregulated heat-shock protein 90 (Hsp90) expression and increased the interaction of Hsp90 with HIF-1α in ischemic brains. The enhanced association of Hsp90 with HIF-1α increased HIF-1α stability. Moreover, Hsp90 inhibition attenuated NAC-induced HIF-1α protein accumulation and diminished NAC-induced neuroprotection in the MCAO model. These results strongly indicate that HIF-1 plays an important role in NAC-mediated neuroprotection and provide a new molecular mechanism involved in the antioxidant’s neuroprotection in ischemic stroke.     

Bimanual training in stroke: How do coupling and symmetry-breaking matter?

Background  

The dramatic consequences of stroke on patient autonomy in daily living activities urged the need for new reliable therapeutic strategies. Recently, bimanual training has emerged as a promising tool to improve the functional recovery of upper-limbs in stroke patients. However, who could benefit from bimanual therapy and how it could be used as a part of a more complete rehabilitation protocol remain largely unknown. A possible reason explaining this situation is that coupling and symmetry-breaking mechanisms, two fundamental principles governing bimanual behaviour, have been largely under-explored in both research and rehabilitation in stroke.     

Plasma interleukin-1β concentration is associated with stroke in sickle cell disease

The pathogenesis of sickle cell disease (HbSS), which has numerous complications including stroke, involves inflammation resulting in alteration of plasma inflammatory protein concentration. We investigated HbSS children with abnormal cerebral blood flow detected by trans-cranial Doppler ultrasound (TCD) who participated in the multi-center stroke prevention (STOP) study, to determine if plasma inflammatory protein concentration is associated with the outcome of stroke. Thirty-nine plasma samples from HbSS participants with elevated TCD who had no stroke, HbSS-NS (n = 13) or had stroke, HbSS-S (n = 13), HbSS steady-state controls (n = 7) and controls with normal hemoglobin, HbAA (n = 6), were analyzed simultaneously for 27 circulating inflammatory proteins. Logistic regression and receiver operating characteristics curve analysis of stroke on plasma inflammatory mediator concentration, adjusted for age and gender, demonstrated that interleukin-1β (IL-1β) was protective against stroke development (HbSS-NS = 19, 17–23, HbSS-S = 17, 16–19 pg/mL, median and 25th–75th percentile; odds ratio = 0.59, C.I. = 0.36–0.96) and was a good predictor of stroke (area under curve = 0.852). This result demonstrates a strong association of systemic inflammation with stroke development in HbSS via moderately increased plasma IL-1β concentration, which is furthermore associated with a decreased likelihood of stroke in HbSS.     

Hybrid molecules of scutellarein and tertramethylpyrazine’s active metabolites for ischemic stroke

A series of hybrid molecules of scutellarein and tertramethylpyrazine’s active metabolites have been synthesized. Compared to the original compound, these prepared compounds exhibited higher water solubility, more appropriate logP and better stability. Importantly, compounds 11b, 11d and 11e showed improved neuroprotective activity against the H₂O₂-induced cell death in PC12 cells, and better antithrombosis activity. The optimized compound 11b was further evaluated by cerebral ischemia/ reperfusion in the middle cerebral artery occlusion (MCAO) model, the results showed that the compound could significantly reduce the infarct area and decrease the neuronal cell damage in CA1 pyramidal neurons. Overall, we demonstrated that the twin drug strategy could be applied in the development of agents for the treatment of ischemic stroke.     

Naloxone or TRH fails to improve neurologic deficits in gerbil models of “stroke”

The effects of naloxone or thyrotropin releasing hormone (TRH) upon neurologic outcome were evaluated in gerbil models of cerebral ischemia. Following temporary bilateral carotid occlusion, hypotension was transiently reversed by these endorphin antagonists. However, neither drug altered time to awaken, time to death, or the severity of neurologic signs (ptosis, movement, retracted paws, circling, righting reflexes, seizures, or opisthotonus) when evaluated by a blinded rater. Hot plate escape and roto-rod performance were also unaltered by naloxone or TRH; TRH, but not naloxone, increased respiratory rates. Thus, the transient improvement of cardiorespiratory function produced by these drugs is unrelated to the morbidity and mortality associated with temporary cerebral ischemia in the gerbil. Additional studies evaluating the effects of naloxone or TRH upon neurologic outcome following permanent unilateral carotid occlusion also failed to show any therapeutic effects of these drugs. Both morphine and TRH exacerbated the effects of ischemia. Of gerbils which developed neurologic impairment, the deficit was usually ipsilateral to the occluded carotid. Collectively, these results indicate that neither naloxone nor TRH prevents ischemic deficits in the gerbil. Further studies with different cerebral ischemia models in other species are required to clarify the possible therapeutic effects of these drugs in experimental stroke.     

Lipid peroxidation dysregulation in ischemic stroke: Plasma 4-HNE as a potential biomarker?

4-hydroxynonenal (4-HNE) is a major aldehyde produced during the lipid peroxidation of ω-6 polyunsaturated fatty acids. Recently, 4-HNE has been reported to contribute to the pathogenesis of neuronal diseases such as Alzheimer's disease. However, the role of 4-HNE in ischemic stroke is unclear yet. In this study, we found that plasma 4-HNE concentrations were higher in the genetic stroke-prone rats (stroke-prone spontaneously hypertensive rats) and experimental stroke rats with middle cerebral artery occlusion (MCAO). Moreover, administration of 4-HNE via intravenous injection before MCAO surgery not only enlarged cerebral ischemia-induced infarct area, but also increased oxidative stress in brain tissue, which was evidenced by the enhanced ROS/MPA levels, and the reduced GSH/GSSG ratio and MnSOD levels. Overexpression of aldehyde dehydrogenasesbcl-2 (ALDH2), an enzyme catalyses 4-HNE, rescued neuronal survival against 4-HNE treatment in PC12 cells. The plasma 4-HNE concentrations in patients with ischemic stroke were higher than those in control subjects. In a small sample population (N=60), the plasma 4-HNE concentration was positively correlated with the plasma homocysteine concentration, a risk factor for ischemic stroke. Taken together, our study suggests that the plasma 4-HNE level is a potential biomarker for ischemic stroke.     

Traditional Chinese medicine, a solution for reducing dual stroke risk factors at once?

Based on genome wide association studies (GWAS), the activities of phosphodiesterase 4D (PDE4D) and 5-Lipoxygenase activating protein (ALOX5AP) were suggested as two of the major factors involved in ischemic stroke risks. Uncontrolled PDE4D activities often lead to cAMP-induced stroke and cardiovascular diseases. Overexpression of ALOX5AP, on the other hand, had been shown to play a major role in inflammation pathway that could induce the development of atherosclerosis and stroke. To eliminate the risk factors that lead to stroke, we reported the identification and analysis of dual-targeting compounds that could reduce PDE4D and ALOX5AP activities from traditional Chinese medicine (TCM). We employed world's largest TCM database, TCM Database@Taiwan, for in silico drug identification. We also introduced machine learning predictive models, as well as pharmacophore model, for characterizing the drug-like candidates. Both myristic acid and pentadecanoic acid were identified. The follow-up analysis on molecular dynamics simulation further determined the major roles of the carboxyl group for forming stable molecular interactions. Intriguingly, the carboxyl group demonstrated different bonding patterns with PDE4D and ALOX5AP, through electrostatic interaction and hydrogen bonds, respectively. In addition, the large volume occupied by the ligand hydrophobic regions could achieve inhibition through occupying the vacant spaces in the binding site. These pharmacophores held true for both candidates against each protein targets. Hence, we proposed the presence of the carboxyl group and hydrophobic regions as potent dual targeting features that inhibit both PDE4D and ALOX5AP activities.