Inflammation Mediated Epileptogenesis as Possible Mechanism Underlying Ischemic Post-stroke Epilepsy

Exploratory study of blood biomarkers in patients with post-stroke epilepsy

INTRODUCTION

In addition to clinical factors, blood-based biomarkers can provide useful information on the risk of developing post-stroke epilepsy (PSE). Our aim was to identify serum biomarkers at stroke onset that could contribute to predicting patients at higher risk of PSE.

PATIENTS AND METHODS

From a previous study in which 895 acute stroke patients were followed-up, 51 patients developed PSE. We selected 15 patients with PSE and 15 controls without epilepsy. In a biomarker discovery setting, 5 Olink panels of 96 proteins each, were used to determine protein levels. Biomarkers that were down-regulated and overexpressed in PSE patients, and those that showed the strongest interactions with other proteins were validated using an enzyme-linked immunosorbent assay in samples from 50 PSE patients and 50 controls. A ROC curve analysis was used to evaluate the predictive ability of significant biomarkers to develop PSE.

RESULTS

Mean age of the PSE discovery cohort was 68.56 ± 15.1, 40% women and baseline NIHSS 12 [IQR 1-25]. Nine proteins were down-expressed: CASP-8, TNFSF-14, STAMBP, ENRAGE, EDA2R, SIRT2, TGF-alpha, OSM and CLEC1B. VEGFa, CD40 and CCL4 showed greatest interactions with the remaining proteins. In the validation analysis, TNFSF-14 was the single biomarker showing statistically significant downregulated levels in PSE patients (p = 0.006) and it showed a good predictive capability to develop PSE (AUC 0.733, 95% CI 0.601-0.865).

DISCUSSION AND CONCLUSION

Protein expression in PSE patients differs from that of non-epileptic stroke patients, suggesting the involvement of several different proteins in post-stroke epileptogenesis. TNFSF-14 emerges as a potential biomarker for predicting PSE.

Risk Factors Associated with Epilepsy Related to Cerebrovascular Disease: A Systematic Review and Meta-Analysis

Background and Objective

Stroke is one of the most frequent neurological syndromes in the adult population and the cause of 10% of all diagnosed epilepsies. It is attributed to the origin of up to 50% of them in adults >60 years of age. Although a few risk factors have been described and considered when modeling predictive tools, this aspect is still clinically complex. The objective of this study is to describe and compare predictor scales of post stroke epilepsy (PSE) in adult patients with better performance.

Methods

A systematic review and meta-analysis were performed of studies published between 2010 and 2020 and found in PubMed, Scopus, EMBASE, LILACS, BVS, Google Scholar, and CENTRAL databases. Sixteen studies were included with a total of 298,694 patients with a diagnosis of stroke, 5590 presented late seizures (LS).

Results

Hemorrhage, cortical involvement, and early seizure were the elements most associated with the risk of presenting late seizures. The SeLECT score demonstrated a low risk of bias with a high predictive ability in patients with ischemic stroke (AUC: 0.77 [95% CI: 0.71-0.82]). In patients with hemorrhagic stroke, the CAVE score demonstrated adequate predictive ability (AUC: 0.81 [95% CI: 0.76-0.86]), but an uncertain risk of bias. Research has established risk factors for post ictal epilepsy; however, the numerous ways of assessing data in studies and the difference in their designs make the task of producing a predictive scale that covers the most important risk factors and is reliable for application in the clinical setting, regardless of stroke etiology, very arduous.

Conclusion

Hemorrhage, cortical involvement, and early seizure are associated with an increased risk of post ictal epilepsy. Also, elements such as age, traditional vascular risk factors, and functional assessment failed to reflect statistical significance. Finally, further research is required to refine the available predictive tools.

Injury-specific factors in the cerebrospinal fluid regulate astrocyte plasticity in the human brain

The glial environment influences neurological disease progression, yet much of our knowledge still relies on preclinical animal studies, especially regarding astrocyte heterogeneity. In murine models of traumatic brain injury, beneficial functions of proliferating reactive astrocytes on disease outcome have been unraveled, but little is known regarding if and when they are present in human brain pathology. Here we examined a broad spectrum of pathologies with and without intracerebral hemorrhage and found a striking correlation between lesions involving blood-brain barrier rupture and astrocyte proliferation that was further corroborated in an assay probing for neural stem cell potential. Most importantly, proteomic analysis unraveled a crucial signaling pathway regulating this astrocyte plasticity with GALECTIN3 as a novel marker for proliferating astrocytes and the GALECTIN3-binding protein LGALS3BP as a functional hub mediating astrocyte proliferation and neurosphere formation. Taken together, this work identifies a therapeutically relevant astrocyte response and their molecular regulators in different pathologies affecting the human cerebral cortex.

Multi-inflammatory index as a new predictive and prognostic marker of acute symptomatic seizures in patients with cerebral venous sinus thrombosis

BACKGROUND

The multi-inflammatory index (MII) is a novel marker that indicates the diagnosis, prognosis, and clinical severeness of inflammation-associated diseases. It is indicated that inflammatory biomarkers may help predict the occurrence of acute symptomatic seizures(ASS) after ischemic stroke.

OBJECTIVE

Our goal was to search the predictive and prognostic capability of the MII-1 and MII-2 for ASS in cerebral venous sinus thrombosis (CVST) patients.

METHOD

91 patients with CVST were retrospectively analyzed from the medical records of patients between 2010 and 2023 and divided into the ASS group and non-ASS group. The MII-1 and MII-2 levels on admission, demographic and clinic features, predisposing risk factors, radiological characteristics involving thrombotic cerebral veins, and the type of parenchymal lesions were documented. Modified Rankin Scale (mRS) on admission and at the 3rd month were evaluated to determine the disability.

RESULTS

MII-1 and MII-2 were statistically significantly higher in the ASS group and predictors for the occurrence of seizures with CVST in multivariate analysis. The area under the curve (AUC) of the receiver operating characteristics (ROC) curve for MII-1 was 0.791 (95 %CI = 0.691-0.891, p < 0.001), and AUC for MII-2 was 0.761 (95%CI = 0.660-0.861, p < 0.001). When the clinical variables that were included in the multivariate analysis and MII-1 and MII-2 were combined, the predictive power was greater with the AUC of 0.959. A significant positive correlation was found between mRS at the 3rd month and MII-1 and MII-2 in the ASS group.

CONCLUSION

MII-1 and MII-2 can be used as new predictive and prognostic markers of ASS in patients with CVST.

Inflammation, Anti-inflammatory Interventions, and Post-stroke Cognitive Impairment: a Systematic Review and Meta-analysis of Human and Animal Studies

The pathophysiology and treatment of post-stroke cognitive impairment (PSCI) are not clear. Stroke triggers an inflammatory response, which might affect synapse function and cognitive status. We performed a systematic review and meta-analysis to assess whether patients with PSCI have increased levels of inflammatory markers and whether anti-inflammatory interventions in animals decrease PSCI. We systematically searched PubMed, EMBASE, and PsychInfo for studies on stroke. For human studies, we determined the standardized mean difference (SMD) on the association between PSCI and markers of inflammation. For animal studies, we determined the SMD of post-stroke cognitive outcome after an anti-inflammatory intervention. Interventions were grouped based on proposed mechanism of action. In patients, the SMD of inflammatory markers for those with versus those without PSCI was 0.46 (95% CI 0.18; 0.76; I2 = 92%), and the correlation coefficient between level of inflammation and cognitive scores was - 0.25 (95% CI - 0.34; - 0.16; I2 = 75%). In animals, the SMD of cognition for those treated with versus those without anti-inflammatory interventions was 1.43 (95% CI 1.12; 1.74; I2 = 83%). The largest effect sizes in treated animals were for complement inhibition (SMD = 1.94 (95% CI 1.50; 2.37), I2 = 51%) and fingolimod (SMD = 2.1 (95% CI 0.75; 3.47), I2 = 81%). Inflammation is increased in stroke survivors with cognitive impairment and is negatively correlated with cognitive functioning. Anti-inflammatory interventions seem to improve cognitive functioning in animals. Complement inhibition and fingolimod are promising therapies on reducing PSCI.

MicroRNAs as Potential Biomarkers of Post-Traumatic Epileptogenesis: A Systematic Review

Structural or post-traumatic epilepsy often develops after brain tissue damage caused by traumatic brain injury, stroke, infectious diseases of the brain, etc. Most often, between the initiating event and epilepsy, there is a period without seizures-a latent period. At this time, the process of restructuring of neural networks begins, leading to the formation of epileptiform activity, called epileptogenesis. The prediction of the development of the epileptogenic process is currently an urgent and difficult task. MicroRNAs are inexpensive and minimally invasive biomarkers of biological and pathological processes. The aim of this study is to evaluate the predictive ability of microRNAs to detect the risk of epileptogenesis. In this study, we conducted a systematic search on the MDPI, PubMed, ScienceDirect, and Web of Science platforms. We analyzed publications that studied the aberrant expression of circulating microRNAs in epilepsy, traumatic brain injury, and ischemic stroke in order to search for microRNAs-potential biomarkers for predicting epileptogenesis. Thus, 31 manuscripts examining biomarkers of epilepsy, 19 manuscripts examining biomarkers of traumatic brain injury, and 48 manuscripts examining biomarkers of ischemic stroke based on circulating miRNAs were analyzed. Three miRNAs were studied: miR-21, miR-181a, and miR-155. The findings showed that miR-21 and miR-155 are associated with cell proliferation and apoptosis, and miR-181a is associated with protein modifications. These miRNAs are not strictly specific, but they are involved in processes that may be indirectly associated with epileptogenesis. Also, these microRNAs may be of interest when they are studied in a cohort with each other and with other microRNAs. To further study the microRNA-based biomarkers of epileptogenesis, many factors must be taken into account: the time of sampling, the type of biological fluid, and other nuances. Currently, there is a need for more in-depth and prolonged studies of epileptogenesis.

Third-Generation Antiseizure Medication in the Treatment of Benzodiazepine-Refractory Status Epilepticus in Poststroke Epilepsy: A Retrospective Observational Register-Based Study

BACKGROUND AND OBJECTIVE

Status epilepticus in poststroke epilepsy is a challenging condition because of multiple vascular comorbidities and the advanced age of patients. Data on third-generation antiseizure medication (ASM) in this condition are limited. The aim of this study was to evaluate the efficacy of third-generation ASMs in the second- or third-line therapy of benzodiazepine-refractory status epilepticus in poststroke epilepsy following acute ischemic stroke.

METHODS

Data on the effectiveness of third-generation ASMs in patients with status epilepticus in poststroke epilepsy were gathered from two German Stroke Registries and the Mainz Epilepsy Registry. We included only cases with epilepsy remote to the ischemic event. No patients with acute symptomatic seizures were included. The following third-generation ASMs were included: brivaracetam, lacosamide, eslicarbazepine, perampanel, topiramate, and zonisamide. The assessment of effectiveness was based on seizure freedom within 48 h since the start of therapy with the respective ASM. Seizure freedom was evaluated both clinically (clinical evaluation at least three times per day) and by daily electroencephalogram records.

RESULTS

Of the 138 patients aged 70.8 ± 8.1 years with benzodiazepine-refractory status epilepticus in ischemic poststroke epilepsy, 33 (23.9%) were treated with lacosamide, 24 (17.4%) with brivaracetam, 23 (16.7%) with eslicarbazepine, 21 (15.2%) with perampanel, 20 (14.5%) with topiramate, and 17 (12.3%) with zonisamide. Seizure freedom within 48 h was achieved in 66.7% of patients with lacosamide, 65.2% with eslicarbazepine, 38.1% with perampanel, 37.5% with brivaracetam, 35.0% with topiramate, and 35.3% with zonisamide (p < 0.05 for comparison of lacosamide or eslicarbazepine to other ASMs).

CONCLUSIONS

Based on these data, lacosamide and eslicarbazepine might be more favorable in the treatment of refractory status epilepticus in poststroke epilepsy, when administered as second- or third-line ASMs before anesthesia. Because of the fact that these ASMs share the same mechanism of action (slow inactivation of sodium channels), our findings could motivate further research on the role that this pharmaceutical mechanism of action has in the treatment of poststroke epilepsy.

CLINICAL TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov (NCT05267405).

ROS/Electro Dual-Reactive Nanogel for Targeting Epileptic Foci to Remodel Aberrant Circuits and Inflammatory Microenvironment

Medicinal treatment against epilepsy is faced with intractable problems, especially epileptogenesis that cannot be blocked by clinical antiepileptic drugs (AEDs) during the latency of epilepsy. Abnormal circuits of neurons interact with the inflammatory microenvironment of glial cells in epileptic foci, resulting in recurrent seizures and refractory epilepsy. Herein, we have selected phenytoin (PHT) as a model drug to derive a ROS-responsive and consuming prodrug, which is combined with an electro-responsive group (sulfonate sodium, SS) and an epileptic focus-recognizing group (α-methyl-l-tryptophan, AMT) to form hydrogel nanoparticles (i.e., a nanogel). The nanogel will target epileptic foci, release PHT in response to a high concentration of reactive oxygen species (ROS) in the microenvironment, and inhibit overexcited circuits. Meanwhile, with the clearance of ROS, the nanogel can also reduce oxidative stress and alleviate microenvironment inflammation. Thus, a synergistic regulation of epileptic lesions will be achieved. Our nanogel is expected to provide a more comprehensive strategy for antiepileptic treatment.

Thalidomide Attenuates Epileptogenesis and Seizures by Decreasing Brain Inflammation in Lithium Pilocarpine Rat Model

Thalidomide (TAL) has shown potential therapeutic effects in neurological diseases like epilepsy. Both clinical and preclinical studies show that TAL may act as an antiepileptic drug and as a possible treatment against disease development. However, the evidence for these effects is limited. Therefore, the antiepileptogenic and anti-inflammatory effects of TAL were evaluated herein. Sprague Dawley male rats were randomly allocated to one of five groups (n = 18 per group): control (C); status epilepticus (SE); SE-TAL (25 mg/kg); SE-TAL (50 mg/kg); and SE-topiramate (TOP; 60mg/kg). The lithium-pilocarpine model was used, and one day after SE induction the rats received pharmacological treatment for one week. The brain was obtained, and the hippocampus was micro-dissected 8, 18, and 28 days after SE. TNF-α, IL-6, and IL-1β concentrations were quantified. TOP and TAL (50 mg/kg) increased the latency to the first of many spontaneous recurrent seizures (SRS) and decreased SRS frequency, as well as decreasing TNF-α and IL-1β concentrations in the hippocampus. In conclusion, the results showed that both TAL (50 mg/kg) and TOP have anti-ictogenic and antiepileptogenic effects, possibly by decreasing neuroinflammation.

Neutrophil to lymphocyte ratio is associated with the epilepsy after primary intracerebral hemorrhage

BACKGROUND

Post-stroke epilepsy (PSE) is one of the major sequelae of stroke. Inflammation has been implicated in the development of stroke. The study aimed to explore the relationship between neutrophil-to-lymphocyte ratio (NLR) levels and epilepsy in patients with primary intracerebral hemorrhage (ICH).

METHODS

A retrospective study was performed on 1132 patients with first-time ICH. Blood samples were obtained at admission after ICH. Patients included in the study were classified into three groups according to NLR tertiles. Logistic regression was used to analyze the relationship between NLR levels and the occurrence of PSE.

RESULTS

The occurrence of PSE was significantly correlated with NLR levels (r = 0.118, P < 0.001). Patients with PSE had higher NLR levels than those without PSE. After adjusting for potential confounders, high NLR was independently associated with an increased risk of PSE (OR = 1.861, 95% CI 1.032-3.355, P = 0.039). Neutrophil-to-lymphocyte ratio levels were independently associated with the occurrence of PSE in the poor functional outcome group, while this association was not significant in the favorable functional outcome group. The model (cortical involvement + hematoma volume + early seizures + NLR) showed good prognostic performance.

CONCLUSION

High NLR at admission is associated with an increased risk of PSE, which suggests that NLR may play a role in risk stratification in patients with ICH.

Silencing TLR4 using an ultrasound-targeted microbubble destruction-based shRNA system reduces ischemia-induced seizures in hyperglycemic rats

The toll-like receptor 4 (TLR4) pathway is involved in seizures. We investigated whether ultrasound-targeted microbubble destruction (UTMD)-mediated delivery of short hairpin RNA (shRNA) targeting the TLR4 gene (shRNA-TLR4) can reduce ischemia-induced seizures in rats with hyperglycemia. A total of 100 male Wistar rats were randomly assigned to five groups: (1) Sham; (2) normal saline (NS); (3) shRNA-TLR4, where rats were injected with shRNA-TLR4; (4) shRNA-TLR4 + US, where rats were injected with shRNA-TLR4 followed by ultrasound (US) irradiation; and (5) shRNA-TLR4 + microbubbles (MBs) + US, where rats were injected with shRNA-TLR4 mixed with MBs followed by US irradiation. Western blot and immunohistochemical staining were used to measure TLR4-positive cells. Half of the rats in the NS group developed tonic-clonic seizures, and TLR4 expression in the CA3 region of the hippocampus was increased in these rats. In addition, the NS group showed an increased number of TLR4-positive cells compared with the Sham group, while there was a decreased number of TLR4-positive cells in the shRNA, shRNA + US, and shRNA + MBs + US groups. Our findings indicate that the TLR4 pathway is involved in the pathogenesis of ischemia-induced seizures in hyperglycemic rats and that UTMD technology may be a promising strategy to treat brain diseases.

The Association between High Mobility Group Box 1 and Stroke-Associated Pneumonia in Acute Ischemic Stroke Patients

Objective: This study aimed to investigate the association between high-mobility-group box 1 (HMGB1) and stroke-associated pneumonia (SAP) in acute ischemic stroke (AIS) patients. Methods: AIS patients were enrolled in two centers. The serum samples were collected within the first 24 h after admission, and HMGB1 levels were measured by enzyme-linked immunosorbent assay. Logistic regression models were used to calculate the odds ratio (OR) and 95% confidence interval (95% CI) of SAP for HMGB1 concentrations. Restricted cubic splines (RCS) were performed to explore the shapes of the association between HMGB1 concentrations and SAP. Results: From January 2022 to May 2022, a total of 420 AIS patients were enrolled. Ninety-six (22.9%) patients develop SAP. The levels of HMGB1 in the SAP group were higher than those in the non-SAP group (p < 0.001). Using the first quartile of HMGB1 group as a reference, patients in the fourth quartile of HMGB1 group had the highest likelihood of experiencing SAP in the unadjusted model (OR = 3.687; 95% CI: 1.851−7.344), age- and sex-adjusted model (OR = 3.511; 95% CI: 1.725−7.147), and multivariable-adjusted model (OR = 2.701; 95% CI: 1.045−6.981). HMGB1 was also independently associated with SAP as a continuous variable in the unadjusted model (OR = 1.132; 95% CI: 1.069−1.199), age- and sex-adjusted model (OR = 1.131; 95% CI: 1.066−1.200), and multivariable-adjusted model (OR = 1.096; 95% CI: 1.011−1.188). RCS showed a linear association between HMGB1 and SAP (p for linear trend = 0.008) Conclusions: HMGB1 might be able to act as a potential biomarker of SAP in AIS patients.

Poststroke Seizure and Epilepsy: A Review of Incidence, Risk Factors, Diagnosis, Pathophysiology, and Pharmacological Therapies

Stroke is the most common cause of epilepsy and ultimately leads to a decrease in the quality of life of those affected. Ischemic and hemorrhagic strokes can both lead to poststroke epilepsy (PSE). Significant risk factors for PSE include age < 65age less than 65 years, stroke severity measured by the National Institutes of Health Stroke Scale (NIHSS), cortical involvement, and genetic factors such as TRPM6 polymorphism. The diagnosis of PSE is made by using imaging modalities, blood biomarkers, and prognostic criteria. Electroencephalography (EEG) is currently the gold standard to diagnose PSE, while new combinations of modalities are being tested to increase diagnostic specificity. This literature review uncovers a newly found mechanism for the pathology of poststroke epilepsy. The pathogenesis of early-onset and late-onset is characterized by sequelae of neuronal cellular hypoxia and disruption of the blood-brain barrier, respectively. Interleukin-6 is responsible for increasing the activity of glial cells, causing gliosis and hyperexcitability of neurons. Epinephrine, high-mobility group protein B1, downregulation of CD32, and upregulation of HLA-DR impact the pathology of poststroke epilepsy by inhibiting the normal neuronal immune response. Decreased levels of neuropeptide Y, a neurotransmitter, act through multiple unique mechanisms, such as inhibiting intracellular Ca²⁺ accumulation and acting as an anti-inflammatory, also implemented in the worsening progression of poststroke epilepsy. Additionally, CA1 hippocampal resonant neurons that increase theta oscillation are associated with poststroke epilepsy. Hypertensive small vessel disease may also have an implication in the temporal lobe epilepsy by causing occult microinfarctions. Furthermore, this review highlights the potential use of statins as primary prophylaxis against PSE, with multiple studies demonstrating a reduction in incidence using statins alone, statins in combination with antiepileptic drugs (AEDs), and statins with aspirin. The evidence strongly suggests that the second generation AEDs are a superior treatment method for PSE. Data from numerous studies demonstrate their relative lack of significant drug interactions, increased tolerability, and potential superiority in maintaining seizure-free status.

Neuroprotective effects of Lasmiditan and Sumatriptan in an experimental model of post-stroke seizure in mice: Higher effects with concurrent opioid receptors or KATP channels inhibitors

BACKGROUND

Early post-stroke seizure frequently occurs in stroke survivors within the first few days and is associated with poor functional outcomes. Therefore, efficient treatments of such complications with less adverse effects are pivotal. In this study, we investigated the possible beneficial effects of lasmiditan and sumatriptan against post-stroke seizures in mice and explored underlying mechanisms in their effects.

METHODS

Stroke was induced by double ligation of the right common carotid artery in mice. Immediately after the ligation, lasmiditan (0.1 mg/kg, intraperitoneally [i.p.]) or sumatriptan (0.03 mg/kg, i.p.) were administered. Twenty-four hours after the stroke induction, seizure susceptibility was evaluated using the pentylenetetrazole (PTZ)-induced clonic seizure model. In separate experiments, naltrexone (a non-specific opioid receptor antagonist) and glibenclamide (a K_ATP channel blocker) were administered 15 min before lasmiditan or sumatriptan injection. To evaluate the underlying signaling pathways, ELISA analysis of inflammatory cytokines (TNF-α and IL-1β) and western blot analysis of anti- and pro-apoptotic markers (Bcl-2 and Bax) were performed on mice isolated brain tissues.

RESULTS

Lasmiditan (0.1 mg/kg, i.p.) and sumatriptan (0.03 mg/kg, i.p.) remarkably decreased seizure susceptibility in stroke animals by reducing inflammatory cytokines and neuronal apoptosis. Concurrent administration of naltrexone (10 mg/kg, i.p.) or glibenclamide (0.3 mg/kg, i.p.) with lasmiditan or sumatriptan resulted in a higher neuroprotection against clonic seizures and efficiently reduced the inflammatory and apoptotic markers.

CONCLUSION

Lasmiditan and sumatriptan significantly increased post-stroke seizure thresholds in mice by suppressing inflammatory cytokines and neuronal apoptosis. Lasmiditan and sumatriptan seem to exert higher effects on seizure threshold with concurrent administration of the opioid receptors or K_ATP channels modulators.

Pharmacological perspectives and mechanisms involved in epileptogenesis

Background

Epileptogenesis can be defined as the process by which a previously healthy brain develops a tendency toward recurrent electrical activity, occurring in three phases: first as an initial trigger (such as stroke, infections, and traumatic brain injury); followed by the latency period and the onset of spontaneous and recurrent seizures which characterizes epilepsy.

Main body

The mechanisms that may be involved in epileptogenesis are inflammation, neurogenesis, migration of neurons to different regions of the brain, neural reorganization, and neuroplasticity.In recent years, experimental studies have enabled the discovery of several mechanisms involved in the process of epileptogenesis, mainly neuroinflammation, that involves the activation of glial cells and an increase in specific inflammatory mediators. The lack of an experimental animal model protocol for epileptogenic compounds contributes to the difficulty in understanding disease development and the creation of new drugs.

Conclusion

To solve these difficulties, a new approach is needed in the development of new AEDs that focus on the process of epileptogenesis and the consolidation of animal models for studies of antiepileptogenic compounds, aiming to reach the clinical phases of the study. Some examples of these compounds are rapamycin, which inhibits mTOR signaling, and losartan, that potentiates the antiepileptogenic effect of some AEDs. Based on this, this review discusses the main mechanisms involved in epileptogenesis, as well as its pharmacological approach.

Post-stroke epilepsy and risk of all-cause mortality: A systematic review and meta-analysis of cohort studies

OBJECTIVE

Post-stroke epilepsy (PSE) has been suggested as a predictor of poor prognosis. We aimed to evaluate the association between PSE and all-cause mortality via a meta-analysis.

METHODS

Relevant cohort studies were identified by search of electronic databases including PubMed, Embase, and Web of Science. Two authors independently performed database search, data collection, and study quality evaluation. A randomized-effect model incorporating the possible between-study heterogeneity was used to pool the results.

RESULTS

Overall, ten cohort studies including 177,929 patients with stroke contributed to the meta-analysis. Of them, 15,836 (8.9%) had PSE during a mean follow-up of 4 years. Compared to stroke survivors without PSE, patients with PSE had a significantly increased risk of all-cause death (odds ratio [OR]: 1.68, 95% confidence interval: 1.51-1.87, p < 0.001; I² = 80%). Subgroup analyses showed consistent association in patients with ischemic and hemorrhagic stroke, in prospective and retrospective studies, in PSE diagnosed as unprovoked seizure occurred more than 7 days and 14 days after stroke, in studies with follow-up durations within or over 5 years, and in studies with different quality scores (p for subgroup effect all < 0.05). The Galbraith plot identified three outlier studies which may contribute to the heterogeneity of the meta-analysis, and all of the three studies were database-linked studies. The between-study heterogeneity was significantly reduced after removing the three database-linked studies (OR: 1.39, 95% CI: 1.18-1.62, p < 0.001; I² = 0%).

CONCLUSION

PSE was associated with a higher risk of all-cause mortality.

Hypoxic/Ischemic Inflammation, MicroRNAs and δ-Opioid Receptors: Hypoxia/Ischemia-Sensitive Versus-Insensitive Organs

Hypoxia and ischemia cause inflammatory injury and critically participate in the pathogenesis of various diseases in various organs. However, the protective strategies against hypoxic and ischemic insults are very limited in clinical settings up to date. It is of utmost importance to improve our understanding of hypoxic/ischemic (H/I) inflammation and find novel therapies for better prevention/treatment of H/I injury. Recent studies provide strong evidence that the expression of microRNAs (miRNAs), which regulate gene expression and affect H/I inflammation through post-transcriptional mechanisms, are differentially altered in response to H/I stress, while δ-opioid receptors (DOR) play a protective role against H/I insults in different organs, including both H/I-sensitive organs (e.g., brain, kidney, and heart) and H/I-insensitive organs (e.g., liver and muscle). Indeed, many studies have demonstrated the crucial role of the DOR-mediated cyto-protection against H/I injury by several molecular pathways, including NLRP3 inflammasome modulated by miRNAs. In this review, we summarize our recent studies along with those of others worldwide, and compare the effects of DOR on H/I expression of miRNAs in H/I-sensitive and -insensitive organs. The alternation in miRNA expression profiles upon DOR activation and the potential impact on inflammatory injury in different organs under normoxic and hypoxic conditions are discussed at molecular and cellular levels. More in-depth investigations into this field may provide novel clues for new protective strategies against H/I inflammation in different types of organs.