Hematology and inflammatory signaling of intracerebral hemorrhage

Application value of neutrophil to lymphocyte ratio and platelet to lymphocyte ratio in predicting stress ulcer after acute cerebral hemorrhage surgery

OBJECTIVE

The Platelet-to-Lymphocyte Ratio (PLR) and Neutrophil-to-Lymphocyte Ratio (NLR) are established biomarkers that are associated with the severity, progression, and fatality of diseases. This study aimed to determine their predictive value for the occurrence of stress ulcers (SU) following surgery for acute cerebral hemorrhage.

METHODS

Retrospective data from 210 patients with acute cerebral hemorrhage hospitalized between June 2020 and March 2023 were analyzed. Patients were categorized into two groups based on the occurrence of SU post-surgery: the SU group (42 patients) and the non-SU group (168 patients). Clinical characteristics of both groups were compared, and a multivariate logistic regression was conducted to identify independent risk factors for SU. The study evaluated the predictive value of NLR and PLR, individually and in combination, for predicting SU using Receiver Operating Characteristic (ROC) curves.

RESULTS

We observed significant differences between the SU and non-SU groups in several parameters, including GCS score, absolute neutrophils, NLR, PLR, postoperative tracheotomy, and intracranial infection (P < 0.05). Our multivariate logistic regression analysis identified four independent risk factors for SU in patients undergoing surgery for acute cerebral hemorrhage: GCS score, NLR, PLR, and fasting blood glucose (P < 0.05). Furthermore, ROC analysis demonstrated that the combination of NLR and PLR exhibited the highest AUC, sensitivity, and specificity in predicting SU following surgery for acute cerebral hemorrhage (P < 0.001), with values of 0.864 (95 % CI: 0.776-0.953), 0.778 (95 % CI: 0.658-0.899), and 0.941 (95 % CI: 0.889-0.993) respectively.

CONCLUSION

This study highlighted the combined application of PLR and NLR as a significant predictor of SU in patients post-acute cerebral hemorrhage surgery.

A machine learning model based on results of a comprehensive radiological evaluation can predict the prognosis of basal ganglia cerebral hemorrhage treated with neuroendoscopy

Introduction

Spontaneous intracerebral hemorrhage is the second most common subtype of stroke. Therefore, this study aimed to investigate the risk factors affecting the prognosis of patients with basal ganglia cerebral hemorrhage after neuroendoscopy.

Methods

Between January 2020 and January 2024, 130 patients with basal ganglia cerebral hemorrhage who underwent neuroendoscopy were recruited from two independent centers. We split this dataset into training (n = 79), internal validation (n = 22), and external validation (n = 29) sets. The least absolute shrinkage and selection operator-regression algorithm was used to select the top 10 important radiomic features of different regions (perioperative hemorrhage area [PRH], perioperative surround area [PRS], postoperative hemorrhage area [PSH], and postoperative edema area [PSE]). The black hole, island, blend, and swirl signs were evaluated. The top 10 radiomic features and 4 radiological features were combined to construct the k-nearest neighbor classification (KNN), logistic regression (LR), and support vector machine (SVM) models. Finally, the performance of the perioperative hemorrhage and postoperative edema machine learning models was validated using another independent dataset (n = 29). The primary outcome is mRS at 6 months after discharge. The mRS score greater than 3 defined as functional independence.

Results

A total of 12 models were built: PRH-KNN, PRH-LR, PRH-SVM, PRS-KNN, PRS-LR, PRS-SVM, PSH-KNN, PSH-LR, PSH-SVM, PSE-KNN, PSE-LR, and PSE-SVM, with corresponding areas under the curve (AUC) values in the internal validation set of 0.95, 0.91, 0.94, 0.52, 0.91, 0.54, 0.67, 0.9, 0.72, 0.92, 0.92, and 0.95, respectively. The AUC values of the PRH-KNN, PRH-LR, PRH-SVM, PSE-KNN, PSE-LR, and PSE-SVM in the external validation were 0.9, 0.92, 0.89, 0.91, 0.92, and 0.88, respectively.

Conclusion

The model built based on computed tomography images of different regions accurately predicted the prognosis of patients with basal ganglia cerebral hemorrhage treated with neuroendoscopy. The models built based on the preoperative hematoma area and postoperative edema area showed excellent predictive efficacy in external verification, which has important clinical significance.

Transcriptomic analysis reveals novel hub genes associated with astrocyte autophagy in intracerebral hemorrhage

Introduction

Neuroinflammation serves as a critical local defense mechanism against secondary brain injury following intracerebral hemorrhage (ICH), and astrocytes play a prominent role in this process. In this study, we investigated astrocytic changes during the inflammatory state after ICH to identify new targets for improving the inflammatory response.

Methods

We stimulated mouse astrocytes with lipopolysaccharide (LPS) in vitro and analyzed their transcriptomes via ribonucleic acid sequencing. We created an ICH model in living organisms by injecting autologous blood.

Results

RNA sequencing revealed that 2,717 genes were differentially expressed in the LPS group compared to those in the saline group, with notable enrichment of the autophagic pathway. By intersecting the 2,717 differentially expressed genes (DEGs) with autophagy-related genes, we identified 36 autophagy-related DEGs and seven hub genes. Previous studies and quantitative reverse transcription-polymerase chain reaction results confirmed the increased expression of phosphatidylinositol 3-kinase catalytic subunit type 3 (Pik3c3), AKT serine/threonine kinase 1 (Akt1), and unc-51 like autophagy activating kinase 2 (Ulk2) in astrocytes after ICH. Transcription factors and target miRNAs were identified for the final three DEGs, and 3-methyladenine and leupeptin were identified as potential therapeutic agents for ICH.

Conclusion

Our findings suggest that astrocyte autophagy plays a critical role in ICH complexity, and that Pik3c3, Akt1, and Ulk2 may be potential therapeutic targets.

An exploration on the machine-learning-based stroke prediction model

Introduction

With the rapid development of artificial intelligence technology, machine learning algorithms have been widely applied at various stages of stroke diagnosis, treatment, and prognosis, demonstrating significant potential. A correlation between stroke and cytokine levels in the human body has recently been reported. Our study aimed to establish machine-learning models based on cytokine features to enhance the decision-making capabilities of clinical physicians.

Methods

This study recruited 2346 stroke patients and 2128 healthy control subjects from Chongqing University Central Hospital. A predictive model was established through clinical experiments and collection of clinical laboratory tests and demographic variables at admission. Three classification algorithms, namely Random Forest, Gradient Boosting, and Support Vector Machine, were employed. The models were evaluated using methods such as ROC curves, AUC values, and calibration curves.

Results

Through univariate feature selection, we selected 14 features and constructed three machine-learning models: Support Vector Machine (SVM), Random Forest (RF), and Gradient Boosting Machine (GBM). Our results indicated that in the training set, the RF model outperformed the GBM and SVM models in terms of both the AUC value and sensitivity. We ranked the features using the RF algorithm, and the results showed that IL-6, IL-5, IL-10, and IL-2 had high importance scores and ranked at the top. In the test set, the stroke model demonstrated a good generalization ability, as evidenced by the ROC curve, confusion matrix, and calibration curve, confirming its reliability as a predictive model for stroke.

Discussion

We focused on utilizing cytokines as features to establish stroke prediction models. Analyses of the ROC curve, confusion matrix, and calibration curve of the test set demonstrated that our models exhibited a strong generalization ability, which could be applied in stroke prediction.

LncRNA PVT1 promotes neuroinflammation after intracerebral hemorrhage by regulating the miR-128-3p/TXNIP axis

OBJECTIVE

Intracerebral hemorrhage (ICH) has significant morbidity and mortality. TXNIP and the competing endogenous RNA (ceRNA) regulatory mechanism involved in long non-coding RNA (lncRNA) play roles in ICH. We probed the upstream microRNAs (miRNAs)/lncRNAs that regulated TXNIP expression in the ceRNA mechanism.

METHODS

ICH mouse model was established, and ICH secondary injury was simulated in BV2 microglia by hemin treatment. TXNIP was silenced 48 h before ICH modeling. The ICH mouse brain water content (BWC) and brain lesion volume after ICH were recorded. Neuronal apoptosis and neurological deficits were evaluated by double staining of NeuN and TUNEL/modified Garcia/corner turn/forelimb placement tests. Iba1 + microglia number and tumor necrosis factor-α (TNF-α)/interleukin-1β (IL-1β)/IL-10/TXNIP/PVT1/miR-128-3p levels were assessed by immunohistochemistry, Western blot, ELISA, and RT-qPCR. Cell viability/death of BV2 cells conditioned medium-treated neuron HT22 cells were assessed by CCK-8/LDH assays. miRNA that had a targeted binding relationship with TXNIP was screened. The targeted bindings of miR-128-3p to TXNIP/PVT1 to miR-128-3p were verified by dual-luciferase reporter gene assay.

RESULTS

TXNIP knockdown reduced post-ICH microglial activation/release of pro-inflammatory factors/brain edema/brain lesion volume/neurological deficits in mice and increased releases of anti-inflammatory factors. TXNIP/PVT1 knockdown inhibited hemin-induced inflammatory responses in BV2 cells and protected in vitro co-cultured HT22 cells. PVT1 was a sponge of miR-128-3p to repress TXNIP expression. miR-128-3p knockdown diminished PVT1 knockdown-inhibited hemin-induced BV2 cell inflammatory responses/neurotoxicity.

CONCLUSIONS

PVT1 silencing reduced hemin-induced neuroinflammation and had a protective effect on neurons by increasing the targeted inhibition of TXNIP by miR-128-3p.

Association of serum occludin levels and perihematomal edema volumes in intracranial hemorrhage patients

BACKGROUND AND PURPOSE

Perihematomal edema (PHE) is one of the severe secondary damages following intracranial hemorrhage (ICH). Studies showed that blood-brain barrier (BBB) injury contributes to the development of PHE. Previous studies showed that occludin protein is a potential biomarker of BBB injury. In the present study, we investigated whether the levels of serum occludin on admission are associated with PHE volumes in ICH patients.

METHODS

This cross-sectional study included 90ICH patients and 32 healthy controls.The volumes of hematoma and PHE were assessed using non-contrast cranial CT within 30 min of admission. Blood samples were drawn on admission, and the levels of baseline serum occludin were detected using enzyme-linked immunosorbent assay. Partial correlation analysis and multiple linear regression analysis were performed to evaluate the association between serum occludin levels and PHE volumes in ICH patients.

RESULTS

The serum occludin levels in ICH patients were much higher than health controls (median 0.27 vs. 0.13 ng/mL, p < 0.001). At admission, 34 ICH patients (37.78%) had experienced a severe PHE (≥30 mL), and their serum occludin levels were higher compared to those with mild PHE (<30 mL) (0.78 vs. 0.21 ng/mL, p < 0.001). The area under the receiver operating characteristics curve (ROC) of serum occludin level in predicting severe PHE was 0.747 (95% confidence interval CI 0.644-0.832, p < 0.001). There was a significant positive correlation between serum occludin levels and PHE volumes (partial correlation r = 0.675, p < 0.001). Multiple linear regression analysis showed that serum occludin levels remained independently associated with the PHE volumes after adjusting other confounding factors.

CONCLUSION

The present study showed that serum occludin levels at admission were independently correlated with PHE volumes in ICH patients, which may provide a biomarker indicating PHE volume change.

Predictive value of white blood cell to hemoglobin ratio for 30-day mortality in patients with severe intracerebral hemorrhage

Aim

To explore the predictive value of white blood cell to hemoglobin ratio (WHR) for 30-day mortality in patients with intracerebral hemorrhage (ICH).

Methods

In this cohort study, 2,848 patients with ICH were identified in the Medical Information Mart for Intensive Care (MIMIC)-III and MIMIC-IV. Least absolute shrinkage and selection operator (LASSO) regression screened covariates of 30-day mortality of ICH patients. COX regression analysis was used to study the association of different levels of WHR, white blood cell (WBC), and hemoglobin (Hb) with 30-day mortality. The median follow-up time was 30 (20.28, 30.00) days.

Results

In total, 2,068 participants survived at the end of the follow-up. WHR was negatively correlated with the Glasgow Coma Score (GCS) (spearman correlation coefficient = -0.143, p < 0.001), and positively associated with the Sepsis-related Organ Failure Assessment (SOFA) score (spearman correlation coefficient = 0.156, p < 0.001), quick SOFA (qSOFA) score (spearman correlation coefficient = 0.156, p < 0.001), and Simplified Acute Physiology Score II (SAPS-II) (spearman correlation coefficient = 0.213, p < 0.001). After adjusting for confounders, WHR >0.833 (HR = 1.64, 95%CI: 1.39-1.92) and WBC >10.9 K/uL (HR = 1.49, 95%CI: 1.28-1.73) were associated with increased risk of 30-day mortality of patients with ICH. The area under the curve (AUC) value of the prediction model based on WHR and other predictors was 0.78 (95%CI: 0.77-0.79), which was higher than SAPSII (AUC = 0.75, 95%CI: 0.74-0.76), SOFA score (AUC = 0.69, 95%CI: 0.68-0.70) and GCS (AUC = 0.59, 95%CI: 0.57-0.60).

Conclusion

The level of WHR was associated with 30-day mortality in patients with severe ICH, and the WHR-based prediction model might provide a tool to quickly predict 30-day mortality in patients with ICH.

The Role of Induced Pluripotent Stem Cells in the Treatment of Stroke

Stroke is a neurological disorder with high disability and mortality rates. Almost 80% of stroke cases are ischemic stroke, and the remaining are hemorrhagic stroke. The only approved treatment for ischemic stroke is thrombolysis and/or thrombectomy. However, these treatments cannot sufficiently relieve the disease outcome, and many patients remain disabled even after effective thrombolysis. Therefore, rehabilitative therapies are necessary to induce remodeling in the brain. Currently, stem cell transplantation, especially via the use of induced pluripotent stem cells (iPSCs), is considered a promising alternative therapy for stimulating neurogenesis and brain remodeling. iPSCs are generated from somatic cells by specific transcription factors. The biological functions of iPSCs are similar to those of embryonic stem cells (ESCs), including immunomodulation, reduced cerebral blood flow, cerebral edema, and autophagy. Although iPSC therapy plays a promising role in both hemorrhagic and ischemic stroke, its application is associated with certain limitations. Tumor formation, immune rejection, stem cell survival, and migration are some concerns associated with stem cell therapy. Therefore, cell-free therapy as an alternative method can overcome these limitations. This study reviews the therapeutic application of iPSCs in stroke models and the underlying mechanisms and constraints of these cells. Moreover, cell-free therapy using exosomes, apoptotic bodies, and microvesicles as alternative treatments is discussed.

The therapeutic value of adipose-derived pericyte transplantation after intracerebral hemorrhage in rats

Intracerebral hemorrhage (ICH) is a devastating cerebrovascular associated with inflammation and BBB disruption. Pericytes plays a critical role in neurological diseases, while whether pericytes could be utilized to treat ICH remains to be elucidated. Here, we isolated CD146+CD34- pericytes from rat adipose tissues (ADPs). Fluorescence-activated cells maintained their cell morphology and differentiation potential and expressed pericytes markers (CD146, NG2, and PDGFRβ) but not endothelial markers (CD31, CD34, and CD45). ADPs transplantation improved the neuro-behavioral functions in ICH rats and resulted in decreased hematoma volume and neuron loss after ICH. Besides, ADPs graft restrained the infiltration of neutrophils and reactive microgliosis after ICH injury around the peri-hematoma area of rats, as evidenced by increased Iba1- and MPO immunoreactivity. The transplanted pericytes were covered on endothelial cells, and promoted angiogenesis and vascular basement membrane formation in the peri-hematoma area of ICH rats, as shown by double staining of PDGFRβ and CD31/CollagenIV. The decreased brain water content and Evans Blue leakage proved the protective role of ADPs graft on BBB permeability. Finally, transplanted ADPs increased the expression of VE-cadherin, ZO-1, and claudin-5, leading to stable endothelial cell-cell adhesion and tight junction. In conclusion, the transplantation of APDs improved neuronal after ICH, which involved different mechanisms including neuroinflammation regulation and BBB dysfunction recovery. Our results supported that ADPs might be the ideal cell type for ICH therapy and provided insights into the potential cell therapy for further ICH treatment.

The Osaka prognostic score and Naples prognostic score: novel biomarkers for predicting short-term outcomes after spontaneous intracerebral hemorrhage

OBJECTIVES

Poor immune-nutritional status has been associated with an unfavorable outcome in critical illness. The Osaka prognostic score (OPS) and the Naples prognostic score (NPS), based on inflammatory and nutritional status, has been shown to predict prognosis following cancer and other diseases. The aim of this study was to investigate the relationship between the OPS and NPS and the short-term outcomes of patients with intracerebral hemorrhage (ICH).

METHODS

We retrospectively analyzed the clinical data of patients hospitalized with spontaneous ICH (n = 340) at The Second Affiliated Hospital of Chongqing Medical University between August 2016 and August 2021. Inclusion criteria included patients aged between 18 and 70, and if a blood sample was taken for laboratory testing within 24 h of admission (serum C-reactive protein, albumin, total cholesterol, and counts for neutrophils, lymphocytes, and monocytes were collected on admission). Exclusion criteria included a non-spontaneous cause of ICH and patient death during hospitalization. Patients were divided into four groups based on OPS or five groups according to NPS. Outcomes were evaluated by the modified Rankin Scale (mRS) at six months post-ICH hospitalization. An unfavorable outcome was defined as a mRS score ≥ 3.

RESULTS

A total of 289 patients met our inclusion criteria. The unfavorable outcome group had older age, a lower Glasgow Coma Scale score, a higher rate of complications and cerebral herniation, a longer hospital stay, and higher OPS and NPS when compared with the favorable outcome group. Univariate analysis showed that both OPS and NPS were strongly correlated with mRS (r = 0.196,P < 0.001; r = 0.244, P = 0.001, respectively). Multivariate analysis further showed that OPS and NPS were both independent predictors of unfavorable outcomes for patients with ICH with adjusted odds ratios of 1.802 (95% confidence interval [CI]:1.140-2.847, P = 0.012) and 1.702 (95% CI: 1.225-2.635, P = 0.02), respectively. The area under the curve (AUC) of NPS for predicting a poor outcome was 0.732 (95% CI: 0.665-0.799), which was similar to the AUC of OPS 0.724 (95% CI: 0.657-0.792).

CONCLUSIONS

In this cohort, a higher OPS and NPS on admission was associated with poor outcome at six months following ICH, supporting their potential role as markers for predicting the outcome of patients with ICH.

Association Between Soluble Intercellular Adhesion Molecule-1 and Intracerebral Hemorrhage Outcomes in the FAST Trial

BACKGROUND

Neutrophil-mediated inflammation in the acute phase of intracerebral hemorrhage (ICH) worsens outcome in preclinical studies. sICAM-1 (soluble intercellular adhesion molecule-1), an inducible ligand for integrins and cell-cell adhesion molecules, is critical for neutrophil extravasation. We aimed to determine whether serum levels of sICAM-1 are associated with worse outcomes after ICH.

METHODS

We conducted a post hoc secondary analysis of an observational cohort using data from the FAST trial (Factor-VII for Acute Hemorrhagic Stroke Treatment). The study exposure was the admission serum level of sICAM-1. The coprimary outcomes were mortality and poor outcome (modified Rankin Scale score 4-6) at 90 days. Secondary radiological outcomes were hematoma expansion at 24 hours and perihematomal edema expansion at 72 hours. We used multiple linear and logistic regression analyses to test for associations between sICAM-1 and outcomes, after adjustment for demographics, ICH severity characteristics, change in the systolic blood pressure in the first 24 hours, treatment randomization arm, and the time from symptom onset to study drug administration.

RESULTS

Of 841 patients, we included 507 (60%) with complete data. Hematoma expansion occurred in 169 (33%), while 242 (48%) had a poor outcome. In multivariable analyses, sICAM-1 was associated with mortality (odds ratio, 1.53 per SD increase [95% CI, 1.15-2.03]) and poor outcome (odds ratio, 1.34 per SD increase [CI, 1.06-1.69]). In multivariable analyses of secondary outcomes, sICAM-1 was associated with hematoma expansion (odds ratio, 1.35 per SD increase [CI, 1.11-1.66]), but was not associated with log-transformed perihematomal edema expansion at 72 hours. In additional analyses stratified by treatment assignment, similar results were noted in the recombinant activated factor-VII arm, but not in the placebo arm.

CONCLUSIONS

Admission serum levels of sICAM-1 were associated with mortality, poor outcome, and hematoma expansion. Given the possibility of a biological interaction between recombinant activated factor-VII and sICAM-1, these findings highlight the need to further explore the role of sICAM-1 as a potential marker of poor ICH outcomes.

Admission neutrophil-to-lymphocyte ratio to predict 30-day mortality in severe spontaneous basal ganglia hemorrhage

Background

Spontaneous intracerebral hemorrhage (ICH) usually occurs in the basal ganglia and is highly lethal and disabling. The aim of this study was to evaluate the predictors of 30-day mortality in patients with severe spontaneous basal ganglia hemorrhage.

Methods

This retrospective study included patients with severe basal ganglia intracerebral hemorrhage treated in the Third Affiliated Hospital of Soochow University from 2012 to 2018. Demographic, clinical, laboratory and neuroradiological data were collected. The short-term prognosis was evaluated and divided into death within 30-days and survival over 30-days. We studied the factors affecting the prognosis of patients with severe intracerebral hemorrhage, analyzed the parameters related to neutrophil-to-lymphocyte (NLR) at admission, and evaluated the predictive effect of NLR on 30-day mortality.

Results

A total of 105 patients was included in this retrospective study. The 30-day death group had a larger hematoma, a higher probability of ventricular hemorrhage, a higher ICH score and a lower Glasgow Coma Scale (GCS) score on admission. Meanwhile, the patients in the death group had higher White blood cells (WBC) counts, neutrophil counts, NLRs and C-reactive protein (CRP) levels. The risk factors for 30-day death were related to the ICH volume, GCS score, ICH score, WBC count, neutrophil count, NLR and CRP. The univariate receiver operating characteristic (ROC) curve of the risk factors showed that the NLR had the best prediction performance. Mathematical predictive models for ICH patients showed that the model with NLR had better prediction accuracy.

Conclusions

The NLR is expected to be a potential biomarker for predicting the prognosis of patients with severe basal ganglia hemorrhage.

The Role of Ferroptosis in Blood-Brain Barrier Injury

The blood-brain barrier (BBB) is an important barrier that maintains homeostasis within the central nervous system. Brain microvascular endothelial cells are arranged to form vessel walls and express tight junctional complexes that limit the paracellular pathways of the BBB and therefore play a crucial role in ensuring brain function. These vessel walls tightly regulate the movement of ions, molecules, and cells between the blood and the brain, which protect the neural tissue from toxins and pathogens. Primary damage caused by BBB dysfunction can disrupt the expression of tight junctions, transport proteins and leukocyte adhesion molecules, leading to brain edema, disturbances in ion homeostasis, altered signaling and immune infiltration, which can lead to neuronal cell death. Various neurological diseases are known to cause BBB dysfunction, but the mechanism that causes this disorder is not clear. Recently, ferroptosis has been found to play an important role in BBB dysfunction. Ferroptosis is a new form of regulatory cell death, which is caused by the excessive accumulation of lipid peroxides and iron-dependent reactive oxygen species. This review summarizes the role of ferroptosis in BBB dysfunction and the latest progress of ferroptosis mechanism, and further discusses the influence of various factors of ferroptosis on the severity and prognosis of BBB dysfunction, which may provide better therapeutic targets for BBB dysfunction.

A machine learning approach for predicting perihematomal edema expansion in patients with intracerebral hemorrhage

OBJECTIVES

Preventing the expansion of perihematomal edema (PHE) represents a novel strategy for the improvement of neurological outcomes in intracerebral hemorrhage (ICH) patients. Our goal was to predict early and delayed PHE expansion using a machine learning approach.

METHODS

We enrolled 550 patients with spontaneous ICH to study early PHE expansion, and 389 patients to study delayed expansion. Two imaging researchers rated the shape and density of hematoma in non-contrast computed tomography (NCCT). We trained a radiological machine learning (ML) model, a radiomics ML model, and a combined ML model, using data from radiomics, traditional imaging, and clinical indicators. We then validated these models on an independent dataset by using a nested 4-fold cross-validation approach. We compared models with respect to their predictive performance, which was assessed using the receiver operating characteristic curve.

RESULTS

For both early and delayed PHE expansion, the combined ML model was most predictive (early/delayed AUC values were 0.840/0.705), followed by the radiomics ML model (0.799/0.663), the radiological ML model (0.779/0.631), and the imaging readers (reader 1: 0.668/0.565, reader 2: 0.700/0.617).

CONCLUSION

We validated a machine learning approach with high interpretability for the prediction of early and delayed PHE expansion. This new technique may assist clinical practice for the management of neurocritical patients with ICH.

KEY POINTS

• This is the first study to use artificial intelligence technology for the prediction of perihematomal edema expansion. • A combined machine learning model, trained on data from radiomics, clinical indicators, and imaging features associated with hematoma expansion, outperformed all other methods.

Research progress on the protective effects of aucubin in neurological diseases

CONTEXT

Aucubin (AU), an iridoid glycoside that is one of the active constituents of Eucommia ulmoides Oliv. (EUO) (Eucommiaceae), a traditional Chinese medicine, has been extensively studied in the management of neurological diseases (NDs). However, a comprehensive review of its effects and mechanisms in this regard is currently not available.

OBJECTIVE

To compile the protective effects and mechanisms of AU in NDs and provide a basis for further research.

METHODS

We used 'aucubin' as the 'All Fields' or 'MeSH' in PubMed, Web of Science and China National Knowledge Infrastructure without any limitation to search all relevant articles as comprehensively as possible; we selected the articles on AU treatment of NDs for summary.

RESULTS

Studies reviewed herein reported that AU improved the symptoms or prognosis of Parkinson's disease, Alzheimer's disease, intracerebral haemorrhage, diabetic encephalopathy, epilepsy, anxiety and depression, and traumatic brain injury. The pharmacological mechanisms involved in repairing neuronal loss were postulated to include increasing γ-aminobutyric acid (GABA) content in the synapse, promoting differentiation of neural precursor cells into GABAergic neurons, providing antioxidant and anti-neuroinflammation activities, as well as enhancing autophagy and anti-apoptotic actions.

DISCUSSION AND CONCLUSIONS

The protective effects of AU on some NDs have been confirmed. According to the pharmacological effects, AU is also highly likely to have protective effects on other NDs, which can be realized by further in vivo and in vitro basic research, and clinical trials. In the future, AU may be used for clinical prevention or treatment of patients with neurological diseases.

Inflammation and immune cell abnormalities in intracranial aneurysm subarachnoid hemorrhage (SAH): Relevant signaling pathways and therapeutic strategies

Intracranial aneurysm subarachnoid hemorrhage (SAH) is a cerebrovascular disorder associated with high overall mortality. Currently, the underlying mechanisms of pathological reaction after aneurysm rupture are still unclear, especially in the immune microenvironment, inflammation, and relevant signaling pathways. SAH-induced immune cell population alteration, immune inflammatory signaling pathway activation, and active substance generation are associated with pro-inflammatory cytokines, immunosuppression, and brain injury. Crosstalk between immune disorders and hyperactivation of inflammatory signals aggravated the devastating consequences of brain injury and cerebral vasospasm and increased the risk of infection. In this review, we discussed the role of inflammation and immune cell responses in the occurrence and development of aneurysm SAH, as well as the most relevant immune inflammatory signaling pathways [PI3K/Akt, extracellular signal-regulated kinase (ERK), hypoxia-inducible factor-1α (HIF-1α), STAT, SIRT, mammalian target of rapamycin (mTOR), NLRP3, TLR4/nuclear factor-κB (NF-κB), and Keap1/nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/ARE cascades] and biomarkers in aneurysm SAH. In addition, we also summarized potential therapeutic drugs targeting the aneurysm SAH immune inflammatory responses, such as nimodipine, dexmedetomidine (DEX), fingolimod, and genomic variation-related aneurysm prophylactic agent sunitinib. The intervention of immune inflammatory responses and immune microenvironment significantly reduces the secondary brain injury, thereby improving the prognosis of patients admitted to SAH. Future studies should focus on exploring potential immune inflammatory mechanisms and developing additional therapeutic strategies for precise aneurysm SAH immune inflammatory regulation and genomic variants associated with aneurysm formation.

Neuroinflammation of microglia polarization in intracerebral hemorrhage and its potential targets for intervention

Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in neurological diseases, including intracerebral hemorrhage (ICH). Microglia are activated to acquire either pro-inflammatory or anti-inflammatory phenotypes. After the onset of ICH, pro-inflammatory mediators produced by microglia at the early stages serve as a crucial character in neuroinflammation. Conversely, switching the microglial shift to an anti-inflammatory phenotype could alleviate inflammatory response and incite recovery. This review will elucidate the dynamic profiles of microglia phenotypes and their available shift following ICH. This study can facilitate an understanding of the self-regulatory functions of the immune system involving the shift of microglia phenotypes in ICH. Moreover, suggestions for future preclinical and clinical research and potential intervention strategies are discussed.

A blockade of microRNA-155 signal pathway has a beneficial effect on neural injury after intracerebral haemorrhage via reduction in neuroinflammation and oxidative stress

MicroRNAs (miRNAs) have important contributions to multiple pathophysiological processes for cellular response to stress and are considered as promising therapeutic targets with respect to drug development due to their small size, relative ease of delivery, and sequence specificity. Thus, in the current report, we examined the effects of inhibiting miRNA-155 (miR-155) on the levels of pro-inflammatory cytokines (PICs), oxidative stress products as well as vascular endothelial growth factor (VEGF) in the parietal cortex and hippocampus of rats following intracerebral haemorrhage (ICH). Real time PCR was used to examine the levels of miR-155 in the parietal cortex and hippocampus of rats; and ELISA to measure IL-1β, IL-6 and TNF-α, oxidative 8-iso PGF2α and 8-OHdG, and VEGF. Additionally, modified neurological Severity Score (mNSS) was examined to indicate neurological function in animals. In results, with induction of ICH, the levels of miR-155 were amplified in the parietal cortex and hippocampus and this was accompanied with increases of IL-1β, IL-6 and TNF-α; and 8-iso PGF2α and 8-OHdG. Intracerebroventricular infusion of miR-155 inhibitor attenuated the elevation of PICs and amplification of oxidative stress products. Interestingly, miR-155 inhibitor promoted VEGF levels. Furthermore, inhibition of miR-155 led to improvement of neurological deficits in ICH rats. In conclusion, miR-155 signal in the parietal cortex and hippocampus is engaged in the processes of neural injury during ICH and blocking central miR-155 pathway plays a beneficial role in regulating neurological function via reduction in PICs and products of oxidative stress; and enhancement of VEGF. This has implications to target miR-155 and its downstream signal pathway for neuronal dysfunction and vulnerability related to ICH.

The Role of Concomitant Nrf2 Targeting and Stem Cell Therapy in Cerebrovascular Disease

Despite the reality that a death from cerebrovascular accident occurs every 3.5 min in the United States, there are few therapeutic options which are typically limited to a narrow window of opportunity in time for damage mitigation and recovery. Novel therapies have targeted pathological processes secondary to the initial insult, such as oxidative damage and peripheral inflammation. One of the greatest challenges to therapy is the frequently permanent damage within the CNS, attributed to a lack of sufficient neurogenesis. Thus, recent use of cell-based therapies for stroke have shown promising results. Unfortunately, stroke-induced inflammatory and oxidative damage limit the therapeutic potential of these stem cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been implicated in endogenous antioxidant and anti-inflammatory activity, thus presenting an attractive target for novel therapeutics to enhance stem cell therapy and promote neurogenesis. This review assesses the current literature on the concomitant use of stem cell therapy and Nrf2 targeting via pharmaceutical and natural agents, highlighting the need to elucidate both upstream and downstream pathways in optimizing Nrf2 treatments in the setting of cerebrovascular disease.

Quantification of hematoma and perihematomal edema volumes in intracerebral hemorrhage study: Design considerations in an artificial intelligence validation (QUANTUM) study

BACKGROUND

Hematoma and perihematomal edema volumes are important radiographic markers in spontaneous intracerebral hemorrhage. Accurate, reliable, and efficient quantification of these volumes will be paramount to their utility as measures of treatment effect in future clinical studies. Both manual and semi-automated quantification methods of hematoma and perihematomal edema volumetry are time-consuming and susceptible to inter-rater variability. Efforts are now underway to develop a fully automated algorithm that can replace them. A (QUANTUM) study to establish inter-quantification method measurement equivalency, which deviates from the traditional use of measures of agreement and a comparison hypothesis testing paradigm to indirectly infer quantification method measurement equivalence, is described in this article. The Quantification of Hematoma and Perihematomal Edema Volumes in Intracerebral Hemorrhage study aims to determine whether a fully automated quantification method and a semi-automated quantification method for quantification of hematoma and perihematomal edema volumes are equivalent to the hematoma and perihematomal edema volumes of the manual quantification method.

METHODS/DESIGN

Hematoma and perihematomal edema volumes of supratentorial intracerebral hemorrhage on 252 computed tomography scans will be prospectively quantified in random order by six raters using the fully automated, semi-automated, and manual quantification methods. Primary outcome measures for hematoma and perihematomal edema volumes will be quantified via computed tomography scan on admission (<24 h from symptom onset) and on day 3 (72 ± 12 h from symptom onset), respectively. Equivalence hypothesis testing will be conducted to determine if the hematoma and perihematomal edema volume measurements of the fully automated and semi-automated quantification methods are within 7.5% of the hematoma and perihematomal edema volume measurements of the manual quantification reference method.

DISCUSSION

By allowing direct equivalence hypothesis testing, the Quantification of Hematoma and Perihematomal Edema Volumes in Intracerebral Hemorrhage study offers advantages over radiology validation studies which utilize measures of agreement to indirectly infer measurement equivalence and studies which mistakenly try to infer measurement equivalence based on the failure of a comparison two-sided null hypothesis test to reach the significance level for rejection. The equivalence hypothesis testing paradigm applied to artificial intelligence application validation is relatively uncharted and warrants further investigation. The challenges encountered in the design of this study may influence future studies seeking to translate artificial intelligence medical technology into clinical practice.

Inflammatory and oxidative stress markers in intracerebral hemorrhage: Relevance as prognostic markers for quantification of the edema volume

We aimed to analyze the inflammatory and oxidative stress (OS) markers after intracerebral hemorrhage (ICH) and their temporal changes, interaction effects, and prognostic values as biomarkers for the prediction of the edema volume. Our prospective, longitudinal study included a cohort group of 73 conservatively treated patients with ICH, without hematoma expansion or intraventricular bleeding, which were initialized with the same treatment and provided with the same in-hospital care during the disease course. Study procedures included multilevel comprehensive analyses of clinical and neuroimaging data, aligned with the exploration of 19 inflammatory and five OS markers. White blood cells (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), neutrophilia, and lymphopenia peaked 3 days post-ICH, and they showed much stronger correlations with clinical and neuroimaging variables, when compared to the admission values. An intricate interplay among inflammatory (WBC, CRP, neutrophils, neutrophil-to-lymphocyte ratio [NLR], interleukin (IL)-6, and IL-10) and OS mechanisms (catalase activity and advanced oxidation protein products [AOPP]) was detected operating 3-days post-ICH, being assessed as relevant for prediction of the edema. The overall results suggested complex pathology of formation of post-ICH edema, via: (A) Not additive, but statistically significant synergistic interactions between CRP-ESR, neutrophils-CRP, and neutrophils-IL-6 as drivers for the edema formation; (B) Significant antagonistic effect of high protein oxidation on the CRP-edema dependence, suggesting a mechanism of potential OS-CRP negative feedback loop and redox inactivation of CRP. The final multiple regression model separated the third-day variables NLR, CRP × AOPP, and WBC, as significant prognostic biomarkers for the prediction of the edema volume, with NLR being associated with the highest effect size. Our developed mathematical equation with 3D modeling for prediction and quantification of the edema volume might be beneficial for taking timely adequate strategies for prevention of delayed neurological deteriorations.

Defining Delayed Perihematomal Edema Expansion in Intracerebral Hemorrhage: Segmentation, Time Course, Risk Factors and Clinical Outcome

We attempt to generate a definition of delayed perihematomal edema expansion (DPE) and analyze its time course, risk factors, and clinical outcomes. A multi-cohort data was derived from the Chinese Intracranial Hemorrhage Image Database (CICHID). A non-contrast computed tomography (NCCT) -based deep learning model was constructed for fully automated segmentation hematoma and perihematomal edema (PHE). Time course of hematoma and PHE evolution correlated to initial hematoma volume was volumetrically assessed. Predictive values for DPE were calculated through receiver operating characteristic curve analysis and were tested in an independent cohort. Logistic regression analysis was utilized to identify risk factors for DPE formation and poor outcomes. The test cohort’s Dice scores of lesion segmentation were 0.877 and 0.642 for hematoma and PHE, respectively. Overall, 1201 patients were enrolled for time-course analysis of ICH evolution. A total of 312 patients were further selected for DPE analysis. Time course analysis showed the growth peak of PHE approximately concentrates in 14 days after onset. The best cutoff for DPE to predict poor outcome was 3.34 mL of absolute PHE expansion from 4-7 days to 8-14 days (AUC=0.784, sensitivity=72.2%, specificity=81.2%), and 3.78 mL of absolute PHE expansion from 8-14 days to 15-21 days (AUC=0.682, sensitivity=59.3%, specificity=92.1%) in the derivation sample. Patients with DPE was associated with worse outcome (OR: 12.340, 95%CI: 6.378-23.873, P<0.01), and the larger initial hematoma volume (OR: 1.021, 95%CI: 1.000-1.043, P=0.049) was the significant risk factor for DPE formation. This study constructed a well-performance deep learning model for automatic segmentations of hematoma and PHE. A new definition of DPE was generated and is confirmed to be related to poor outcomes in ICH. Patients with larger initial hematoma volume have a higher risk of developing DPE formation.

Inhibiting Microglia-Derived NLRP3 Alleviates Subependymal Edema and Cognitive Dysfunction in Posthemorrhagic Hydrocephalus after Intracerebral Hemorrhage via AMPK/Beclin-1 Pathway

For posthemorrhagic hydrocephalus (PHH) patients, whether occur subependymal edema indicates poor outcomes, partially manifested as cognitive impairment. In the brain, NLRP3 inflammasome mainly derived from microglia/macrophages is involved in proinflammatory and neurodeficits after hemorrhage, and autophagy is vital for neuronal homeostasis and functions. Accumulating evidence suggest that NLRP3 inflammasome and autophagy played an essential role after intracerebral hemorrhage (ICH). We aimed to dissect the mechanisms underlying subependymal edema formation and cognitive dysfunction. Here, based on the hydrocephalus secondary to ICH break into ventricular (ICH-IVH) in rats, this study investigated whether microglia/macrophage-derived NLRP3 induced subependymal edema formation and neuron apoptosis in subventricular zones (SVZ). In the acute phase of ICH-IVH, both the expression of NLRP3 inflammasome of microglia/macrophages and the autophagy of neurons were upregulated. The activated NLRP3 in microglia/macrophages promoted the release of IL-1beta to extracellular, which contributed to excessive autophagy, leading to neurons apoptosis both in vivo and in vitro through the AMPK/Beclin-1 pathway combined with transcriptomics. Administration of MCC950 (NLRP3 inflammasome specific inhibitor) after ICH-IVH significantly reduced edema formation and improved cognitive dysfunction. Thus, inhibiting NLRP3 activation in SVZ may be a promising therapeutic strategy for PHH patients that warrants further investigation.

Potential application of intranasal insulin delivery for treatment of intracerebral hemorrhage: A review of the literature

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke associated with high morbidity and mortality that is considered a medical emergency, mainly managed with adequate blood pressure control and creating a favorable hemostatic condition. However, to date, none of the randomized clinical trials have led to an effective treatment for ICH. It is vital to better understand the mechanisms underlying brain injury to effectively decrease ICH-associated morbidity and mortality. It is well known that initial hematoma formation and its expansion have detrimental consequences. The literature has recently focused on other pathological processes, including oxidative stress, neuroinflammation, blood-brain barrier disruption, edema formation, and neurotoxicity, that constitute secondary brain injury. Since conventional management has failed to improve clinical outcomes significantly, various neuroprotective therapies are tested in preclinical and clinical settings. Unlike intravenous administration, intranasal insulin can reach a higher concentration in the cerebrospinal fluid without causing systemic side effects. Intranasal insulin delivery has been introduced as a novel neuroprotective agent for certain neurological diseases, including ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury. Since there is an overlap of mechanisms causing neuroinflammation in these neurological diseases and ICH, we believe that preclinical studies testing the role of intranasal insulin therapy in ICH are warranted.

Erythrophagocytosis by Microglia/Macrophage in Intracerebral Hemorrhage: From Mechanisms to Translation

Intracerebral hemorrhage (ICH) is a devastating condition characterized by hematoma related mass effect. Microglia/macrophage (M φ) are rapidly recruited in order to remove the red blood cells through erythrophagocytosis. Efficient erythrophagocytosis can detoxify hemolytic products and facilitate neurological recovery after ICH. The underlying mechanisms include modulation of inflammatory response and oxidative stress, among others. It is a dynamic process mediated by a cascade of signal transduction, including “find-me” signals, “eat-me” signals and a set of phagocytotic receptors-ligand pairs that may be exploited as therapeutic targets. This review summarizes mechanistic signaling pathways of erythrophagocytosis and highlights the potential of harnessing M φ-mediated phagocytosis for ICH treatment.

Assessing the Evolution of Intracranial Hematomas by using Animal Models: A Review of the Progress and the Challenges

Stroke has become the second leading cause of death in people aged higher than 60 years, with cancer being the first. Intracerebral hemorrhage (ICH) is the most lethal type of stroke. Using imaging techniques to evaluate the evolution of intracranial hematomas in patients with hemorrhagic stroke is worthy of ongoing research. The difficulty in obtaining ultra-early imaging data and conducting intensive dynamic radiographic imaging in actual clinical settings has led to the application of experimental animal models to assess the evolution of intracranial hematomas. Herein, we review the current knowledge on primary intracerebral hemorrhage mechanisms, focus on the progress of animal studies related to hematoma development and secondary brain injury, introduce preclinical therapies, and summarize related challenges and future directions.

Perihematomal Edema After Intracerebral Hemorrhage: An Update on Pathogenesis, Risk Factors, and Therapeutic Advances

Intracerebral hemorrhage (ICH) has one of the worst prognoses among patients with stroke. Surgical measures have been adopted to relieve the mass effect of the hematoma, and developing targeted therapy against secondary brain injury (SBI) after ICH is equally essential. Numerous preclinical and clinical studies have demonstrated that perihematomal edema (PHE) is a quantifiable marker of SBI after ICH and is associated with a poor prognosis. Thus, PHE has been considered a promising therapeutic target for ICH. However, the findings derived from existing studies on PHE are disparate and unclear. Therefore, it is necessary to classify, compare, and summarize the existing studies on PHE. In this review, we describe the growth characteristics and relevant underlying mechanism of PHE, analyze the contributions of different risk factors to PHE, present the potential impact of PHE on patient outcomes, and discuss the currently available therapeutic strategies.

Y-2 reduces oxidative stress and inflammation and improves neurological function of collagenase-induced intracerebral hemorrhage rats

Intracerebral hemorrhage (ICH) is a devastating disease, and there is currently no specific pharmacological treatment that can improve clinical outcomes. Y-2 sublingual tablets, each containing 30 mg edaravone and 6 mg (+)-borneol, is undergoing a phase III clinical trial for treatment of ischemic stroke in China. The purpose of the present study is to investigate the efficacy and potential mechanism of Y-2 in a rat model of collagenase IV injection induced ICH. Sublingual administration of Y-2 at the dose of 1, 3 and 6 mg/kg improved ICH-induced sensorimotor dysfunction, alleviated cell death and histopathological change, restored the hippocampal long-term potentiation (LTP), reduced brain edema and maintained blood-brain barrier (BBB) integrality in ICH rats. Further study demonstrated that Y-2 could reduce inflammatory response and oxidative stress by decreasing the levels of myeloperoxidase (MPO), ionized calcium-binding adaptor protein-1 (Iba-1), inflammatory cytokines and oxidative products, inhibit transcription factor nuclear factor-κB (NF-κB) activation, cyclooxygenase-2 (COX-2) and matrix metallopeptidase 9 (MMP-9) expression in brain tissue around in the core regions of hematoma. Importantly, the protective efficacy of Y-2 from ICH-induced injury was superior to edaravone. In conclusion, Y-2 sublingual tablets might be a promising therapeutic agent for the treatment of ICH.

Early Perihematomal Edema Expansion: Definition, Significance, and Association with Outcomes after Intracerebral Hemorrhage

Objective

To investigate the association between early perihematomal edema (PHE) expansion and functional outcome in patients with intracerebral hemorrhage (ICH).

Methods

Patients with ICH who underwent initial computed tomography (CT) scans within 6 hours after the onset of symptoms and follow-up CT scans within 24 ± 12 hours were included. Absolute PHE increase was defined as the absolute increase in PHE volume from baseline to 24 hours. A receiver-operating characteristic (ROC) curve was generated to determine the cutoff value for early PHE expansion, which was operationally defined as an absolute increase in PHE volume of >6 mL. The outcome of interest was 3-month poor outcome defined as modified Rankin scale score of ≥4. A multivariable logistic regression procedure was used to assess the association between early PHE expansion and outcome after ICH.

Results

In 233 patients with ICH, 89 (38.2%) patients had poor outcome at 3-month follow-up. Early PHE expansion was observed in 56 of 233 (24.0%) patients. Patients with early PHE expansion were more likely to have poor functional outcome than those without (43.8% vs. 11.8%, p < 0.001). After adjusting for age, admission systolic blood pressure, admission Glasgow Coma Scale score, baseline ICH volume and the presence of intraventricular hemorrhage, and time from onset to CT, early PHE expansion was associated with poor outcome (adjusted odds ratio, 4.25; 95% confidence interval, 1.70–10.60; p = 0.002).

Conclusions

The early PHE expansion was not uncommon in patients with ICH and was correlated with poor outcome following ICH.

Neuroprotective Therapies for Spontaneous Intracerebral Hemorrhage

Patients who survive the initial ictus of spontaneous intracerebral hemorrhage (ICH) remain vulnerable to subsequent injury of the perilesional parenchyma by molecular and cellular responses to the hematoma. Secondary brain injury after ICH, which contributes to long-term functional impairment and mortality, has emerged as an attractive therapeutic target. This review summarizes preclinical and clinical evidence for neuroprotective therapies targeting secondary injury pathways following ICH. A focus on therapies with pleiotropic antiinflammatory effects that target thrombin-mediated chemotaxis and inflammatory cell migration has led to studies investigating statins, anticholinergics, sphingosine-1-phosphate receptor modulators, peroxisome proliferator activated receptor gamma agonists, and magnesium. Attempts to modulate ICH-induced blood-brain barrier breakdown and perihematomal edema formation has prompted studies of nonsteroidal antiinflammatory agents, matrix metalloproteinase inhibitors, and complement inhibitors. Iron chelators, such as deferoxamine and albumin, have been used to reduce the free radical injury that ensues from erythrocyte lysis. Stem cell transplantation has been assessed for its potential to enhance subacute neurogenesis and functional recovery. Despite promising preclinical results of numerous agents, their outcomes have not yet translated into positive clinical trials in patients with ICH. Further studies are necessary to improve our understanding of the molecular events that promote damage and inflammation of the perihematomal parenchyma after ICH. Elucidating the temporal and pathophysiologic features of this secondary brain injury could enhance the clinical efficacy of neuroprotective therapies for ICH.

Cytokine-Laden Extracellular Vesicles Predict Patient Prognosis after Cerebrovascular Accident

Background: A major contributor to disability after hemorrhagic stroke is secondary brain damage induced by the inflammatory response. Following stroke, global increases in numerous cytokines—many associated with worse outcomes—occur within the brain, cerebrospinal fluid, and peripheral blood. Extracellular vesicles (EVs) may traffic inflammatory cytokines from damaged tissue within the brain, as well as peripheral sources, across the blood–brain barrier, and they may be a critical component of post-stroke neuroinflammatory signaling. Methods: We performed a comprehensive analysis of cytokine concentrations bound to plasma EV surfaces and/or sequestered within the vesicles themselves. These concentrations were correlated to patient acute neurological condition by the Glasgow Coma Scale (GCS) and to chronic, long-term outcome via the Glasgow Outcome Scale-Extended (GOS-E). Results: Pro-inflammatory cytokines detected from plasma EVs were correlated to worse outcomes in hemorrhagic stroke patients. Anti-inflammatory cytokines detected within EVs were still correlated to poor outcomes despite their putative neuroprotective properties. Inflammatory cytokines macrophage-derived chemokine (MDC/CCL2), colony stimulating factor 1 (CSF1), interleukin 7 (IL7), and monokine induced by gamma interferon (MIG/CXCL9) were significantly correlated to both negative GCS and GOS-E when bound to plasma EV membranes. Conclusions: These findings correlate plasma-derived EV cytokine content with detrimental outcomes after stroke, highlighting the potential for EVs to provide cytokines with a means of long-range delivery of inflammatory signals that perpetuate neuroinflammation after stroke, thus hindering recovery.

Potential therapeutic effects of Nrf2 activators on intracranial hemorrhage

Intracranial hemorrhage (ICH) is a devastating disease which induces high mortality and poor outcomes including severe neurological dysfunctions. ICH pathology is divided into two types: primary brain injury (PBI) and secondary brain injury (SBI). Although there are numerous preclinical studies documenting neuroprotective agents in experimental ICH models, no effective drugs have been developed for clinical use due to complicated ICH pathology. Oxidative and inflammatory stresses play central roles in the onset and progression of brain injury after ICH, especially SBI. Nrf2 is a crucial transcription factor in the anti-oxidative stress defense system. Under normal conditions, Nrf2 is tightly regulated by the Keap1. Under ICH pathological conditions, such as overproduction of reactive oxygen species (ROS), Nrf2 is translocated into the nucleus where it up-regulates the expression of several anti-oxidative phase II enzymes such as heme oxygenase-1 (HO-1). Recently, many reports have suggested the therapeutic potential of Nrf2 activators (including natural or synthesized compounds) for treating neurodegenerative diseases. Moreover, several Nrf2 activators attenuate ischemic stroke-induced brain injury in several animal models. This review summarizes the efficacy of several Nrf2 activators in ICH animal models. In the future, Nrf2 activators might be approved for the treatment of ICH patients.

Posttraumatic Pancreatitis Four Days after Renal Injury with Massive Retroperitoneal Hematoma

A 25-year-old man accidentally fell from a cliff and hit his right flank on the ground while camping. Initially, he was able to barely walk, but he ultimately became unable to walk at all due to severe flank pain. He had no remarkable personal or family history and was a social drinker. Upon arrival, he showed clear consciousness but was in a hemorrhagic shock state. Enhanced computed tomography (CT) revealed extravasation of contrast medium from the injured right kidney with massive retroperitoneal hematoma. He underwent massive blood transfusion and tracheal intubation followed by renal embolization. His vital signs stabilized on hospital day 2, and he was extubated on day 3. On days 4 and 5, a blood examination revealed increased levels of amylase (360 and 904 IU/L, respectively). Enhanced CT on day 5 did not show signs of severe acute pancreatitis. The maximum amylase level was 1041 IU/L on day 6 and decreased day by day without deterioration of the severity of his acute pancreatitis. He was discharged on day 14. The subacute phase of posttraumatic acute pancreatitis in the present case may have been induced not by direct injury to the pancreas but by several causative factors, such as shock, increased pressure of the retroperitoneal space, or the release of inflammatory mediators from injured tissues or hematoma.

Association of Serum IL-6 (Interleukin 6) With Functional Outcome After Intracerebral Hemorrhage

BACKGROUND AND OBJECTIVES

IL-6 (interleukin 6) is a proinflammatory cytokine and an established biomarker in acute brain injury. We sought to determine whether admission IL-6 levels are associated with severity and functional outcome after spontaneous intracerebral hemorrhage (ICH).

METHODS

We performed an exploratory analysis of the recombinant activated FAST trial (Factor VII for Acute ICH). Patients with admission serum IL-6 levels were included. Regression analyses were used to assess the associations between IL-6 and 90-day modified Rankin Scale. In secondary analyses, we used linear regression to evaluate the association between IL-6 and baseline ICH and perihematomal edema volumes.

RESULTS

Of 841 enrolled patients, we included 552 (66%) with available admission IL-6 levels (mean age 64 [SD 13], female sex 203 [37%]). IL-6 was associated with poor outcome (modified Rankin Scale, 4-6; per additional 1 ng/L, odds ratio, 1.30 [95% CI, 1.04-1.63]; P=0.02) after adjustment for known predictors of outcome after ICH and treatment group. IL-6 was associated with ICH volume after adjustment for age, sex, and ICH location, and this association was modified by location (multivariable interaction, P=0.002), with a stronger association seen in lobar (β, 12.51 [95% CI, 6.47-18.55], P<0.001) versus nonlobar (β 5.32 [95% CI, 3.36-7.28], P<0.001) location. IL-6 was associated with perihematomal edema volume after adjustment for age, sex, ICH volume, and ICH location (β 1.22 [95% CI, 0.15-2.29], P=0.03). Treatment group was not associated with IL-6 levels or outcome.

CONCLUSIONS

In the FAST trial population, higher admission IL-6 levels were associated with worse 90-day functional outcome and larger ICH and perihematomal edema volumes.

Glibenclamide Advantage in Treating Edema After Intracerebral Hemorrhage (GATE-ICH): Study Protocol for a Multicenter Randomized, Controlled, Assessor-Blinded Trial

Introduction: Brain edema after acute intracerebral hemorrhage (ICH) plays a critical role in the secondary injury of ICH and may heighten the potential for a poor outcome. This trial aims to explore the efficacy of small doses of oral glibenclamide in perihematomal edema (PHE) and the prognosis of patients with ICH. Methods and Analysis: The GATE-ICH trial is a multicenter randomized, controlled, assessor-blinded trial. A total of 220 adult patients with acute primary ICH in 28 study centers in China will be randomized to the glibenclamide group (glibenclamide plus guideline-recommended ICH management) or the control group (guideline-recommended ICH management). Multivariate logistic regression will be used to analyze the relationship between the treatments and primary outcome. Study Outcomes: The primary efficacy outcome is the proportion of poor functional outcomes (modified Rankin Scale ≥3) at 90 days after enrollment. The secondary efficacy outcomes include changes in the volume of ICH and PHE between the baseline and follow-up computed tomography scans as well as the clinical scores between the baseline and follow-up assessments. Discussion: The GATE-ICH trial will assess the effects of small doses of oral glibenclamide in reducing the PHE after ICH and improving the 90-day prognosis of patients. Clinical Trial Registration: www.clinicaltrials.gov., NCT03741530. Registered on November 8, 2018. Trial Status: Protocol version: May 6, 2019, Version 5. Recruitment and follow-up of patients is currently ongoing. This trial will be end in the second quarter of 2021.

History of Nonsteroidal Anti-inflammatory Drug Use and Functional Outcomes After Spontaneous Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Preclinical and clinical studies have suggested a potential benefit from COX-2 inhibition on secondary injury activation after spontaneous intracerebral hemorrhage (ICH). The aim of this study was to investigate the effect of pre-admission NSAID use on functional recovery in spontaneous ICH patients.

METHODS

Consecutive adult ICH patients enrolled in the Intracerebral Hemorrhage Outcomes Project (2009-2018) with available 90-day follow-up data were included. Patients were categorized as NSAID (daily COX inhibitor use ≤ 7 days prior to ICH) and non-NSAID users (no daily COX inhibitor use ≤ 7 days prior to ICH). Primary outcome was the ordinal 90-day modified Rankin Scale (mRS) score. Outcomes were compared between cohorts using multivariable regression and propensity score-matched analyses. A secondary analysis excluding aspirin users was performed.

RESULTS

The NSAID and non-NSAID cohorts comprised 228 and 361 patients, respectively. After 1:1 matching, the matched cohorts each comprised 140 patients. The 90-day mRS were comparable between the NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.914 [0.626-1.336], p = 0.644) and matched (aOR = 0.650 [0.392-1.080], p = 0.097) analyses. The likelihood of recurrent ICH at 90 days was also comparable between the NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.845 [0.359-1.992], p = 0.701) and matched analyses (aOR = 0.732 [0.241-2.220], p = 0.581). In the secondary analysis, the non-aspirin NSAID and non-NSAID cohorts comprised 38 and 361 patients, respectively. After 1:1 matching, the matched cohorts each comprised 38 patients. The 90-day mRS were comparable between the non-aspirin NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.615 [0.343-1.101], p = 0.102) and matched (aOR = 0.525 [0.219-1.254], p = 0.147) analyses. The likelihood of recurrent ICH at 90 days was also comparable between the non-aspirin NSAID and non-NSAID cohorts in both the unmatched (aOR = 2.644 [0.258-27.091], p = 0.413) and matched (aOR = 2.586 [0.228-29.309], p = 0.443) analyses. After the exclusion of patients with DNR or withdrawal of care status, NSAID use was associated with lower mRS at 90 days (aOR = 0.379 [0.212-0.679], p = 0.001), lower mRS at hospital discharge (aOR = 0.505 [0.278-0.919], p = 0.025) and lower 90-day mortality rates (aOR = 0.309 [0.108-0.877], p = 0.027).

CONCLUSIONS

History of nonselective COX inhibition may affect functional outcomes in ICH patients. Pre-admission NSAID use did not appear to worsen the severity of presenting ICH or increase the risk of recurrent ICH. Additional clinical studies may be warranted to investigate the effects of pre-admission NSAID use on ICH outcomes.

Lessons from NATURE: methods for traumatic brain injury prevention

Multiple species obtain repetitive head collisions throughout the course of their lifetimes with minimal neurologic deficit. Nature has allowed the unique development of multiple protective mechanisms to help prevent neurotrauma. In this review, we examine the concept of rapid brain movement within the skull 'Slosh' and what nature teaches on how to prevent this from occurring. We look at individual animals and the protective mechanisms at play. Marching from macroscopic down to the molecular level, we pinpoint key elements of neuroprotection that are likely contributing. We also introduce new concepts for neuroprotection and address avenues of further discovery.

A Multi-Model Pipeline for Translational Intracerebral Haemorrhage Research

Apart from acute and chronic blood pressure lowering, we have no specific medications to prevent intracerebral haemorrhage (ICH) or improve outcomes once bleeding has occurred. One reason for this may be related to particular limitations associated with the current pre-clinical models of ICH, leading to a failure to translate into the clinic. It would seem that a breakdown in the 'drug development pipeline' currently exists for translational ICH research which needs to be urgently addressed. Here, we review the most commonly used pre-clinical models of ICH and discuss their advantages and disadvantages in the context of translational studies. We propose that to increase our chances of successfully identifying new therapeutics for ICH, a bi-directional, 2- or 3-pronged approach using more than one model species/system could be useful for confirming key pre-clinical observations. Furthermore, we highlight that post-mortem/ex-vivo ICH patient material is a precious and underused resource which could play an essential role in the verification of experimental results prior to consideration for further clinical investigation. Embracing multidisciplinary collaboration between pre-clinical and clinical ICH research groups will be essential to ensure the success of this type of approach in the future.

Intracerebral haemorrhage: from clinical settings to animal models

Spontaneous intracerebral haemorrhage (ICH) is a devastating type of stroke with high mortality and morbidity and for which no effective treatments are available to date. Much experimental and clinical research have been performed to explore its mechanisms regard the subsequent inflammatory cascade and to seek the potential therapeutic strategies. The aim of this review is to discuss insights from clinical settings that have led to the development of numerous animal models of ICH. Some of the current and future challenges for clinicians to understand ICH are also surveyed.

Valproate Sodium Protects Blood Brain Barrier Integrity in Intracerebral Hemorrhage Mice

Valproate sodium (VPA) is a traditional antiepileptic drug with a neuroprotective role in cerebrovascular disease. After intracerebral hemorrhage (ICH), mechanical compression by hematoma, neuroinflammation, oxidative stress, and cytotoxicity of hematoma lysates caused the destruction of the blood brain barrier (BBB). Targeting BBB is a major therapeutic method for patients with ICH. The purpose of the present study was to explore the role of VPA in preserving BBB integrity in the ICH model and investigate the underlying molecular mechanisms. One hundred and thirty-six adult male CD1 mice were randomly divided into five groups in the study. Mice subjected to ICH were administered intraperitoneally with VPA at 3, 24, and 48 h post-ICH, respectively. Neurobehavioral assessments, BBB permeability, Evans blue fluorescence, hematoma volume, and protein expression were evaluated. The administration of VPA reduced BBB permeability and improved the neurobehavior significantly post-ICH. VPA administration significantly decreased the expression of phosphorylated nuclear factor-kappa B (p-NFκB), matrix metalloproteinases 9 (MMP9), tumor necrosis factorα (TNFα), and interleukin-6 (IL-6), while it enhanced the expression of claudin 5 and occludin in the brain. In conclusion, VPA administration maintained the integrity of BBB after experimental ICH, thus reducing brain edema and improving the neurological outcomes. Therefore, VPA administration might be a new therapeutic method to protect BBB integrity for patients with ICH.

Deferasirox, a trivalent iron chelator, ameliorates neuronal damage in hemorrhagic stroke models

PURPOSE

Intracranial hemorrhage (ICH) is a devastating disease with high mortality and morbidity. After ICH, iron released from the hematoma plays a crucial role in secondary brain injury. Deferasirox (DFR) is a trivalent iron chelator, which was approved to treat iron overload syndrome after transfusion. The aim of the present study was to investigate the protective effects of DFR in both in vitro and in vivo ICH models.

METHODS

Using a hemin-induced SH-SY5Y cell damage model, we performed an intracellular bivalent iron (Fe²⁺) accumulation assay, cell death assay, oxidative stress assessments, and Western blotting analysis. Moreover, the effects of DFR intraventricular administration on hematoma, neurological deficits, and histological alteration were evaluated in an in vivo ICH mouse model by collagenase.

RESULTS

DFR significantly suppressed the intracellular Fe²⁺ accumulation and cell death caused by hemin exposure. These effects were related to the suppression of both reactive oxygen species and lipid peroxidation over-production. In Western blotting analysis, hemin increased the expression of ferritin (an iron storage protein), LC3 and p62 (autophagy-related markers), phosphorylated p38 (a stress response protein), and cleaved-caspase3 and cleaved-poly (adenosine diphosphate ribose) polymerase (PARP) (apoptosis-related makers). However, DFR suppressed the increase of these proteins. In addition, DFR attenuated the neurological deficits until 7 days after ICH without affecting hematoma and injury area. Furthermore, DFR also suppressed microglia/macrophage activation in peri-hematoma area at 3 days after ICH.

CONCLUSION

These findings indicate that DFR might be a useful therapeutic agent for the therapy of ICH.

Genetic underpinnings of cerebral edema in acute brain injury: an opportunity for pathway discovery

Cerebral edema constitutes an important contributor to secondary injury in acute brain injury. The quantification of cerebral edema in neuroimaging, a well-established biomarker of secondary brain injury, represents a useful intermediate phenotype to study edema formation. Population genetics provides powerful tools to identify novel susceptibility genes, biological pathways and therapeutic targets related to brain edema formation. Here, we provide an overview of the pathogenesis of cerebral edema, introduce relevant genetic methods to study this process, and discuss the ongoing research on the genetic underpinnings of edema formation in acute brain injury. The epsilon 2 and 4 variants within the Apolipoprotein E (APOE) gene are associated with worse outcome after traumatic brain injury and intracerebral hemorrhage, and recent studies link these polymorphisms to inflammatory processes that lead to blood-brain barrier disruption and vasogenic edema. For the Haptoglobin gene (HP), the Hp 2-2 genotype associates with worse outcome after acute brain injury, whereas the haptoglobin Hp 1-1 genotype correlates with increased edema in the early phases of intracerebral hemorrhage. Another important protein in cerebral edema is aquaporin 4, coded by the AQP4 gene. AQP4 mutations contribute to the formation of cytotoxic edema, and further genetic research is necessary to help elucidate the mediating mechanism. Findings supporting the target genes outlined above require replication in larger samples and evaluation in non-white populations. These next steps will be significantly facilitated by the rapid changes observed in the field of population genetics, including large international collaborations, open access to genetic data, and significant reductions in the cost of genotyping technologies.

TREM2 activation attenuates neuroinflammation and neuronal apoptosis via PI3K/Akt pathway after intracerebral hemorrhage in mice

BACKGROUND

Neuroinflammation is an important host defense response to secondary brain injury after intracerebral hemorrhage (ICH). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effects by attenuating neuroinflammation in experimental ischemic stroke. Recent studies suggest that apolipoprotein E (apoE) is a novel, high-affinity ligand of TREM2. This study aimed to investigate the effects of TREM2 activation on neuroinflammation and neuronal apoptosis in a mouse model of ICH.

METHODS

Adult male CD1 mice (n = 216) were subjected to intrastriatal injection of bacterial collagenase. The TREM2 ligand, apoE-mimetic peptide COG1410 was administered intranasally at 1 h after ICH induction. To elucidate the underlying mechanism, TREM2 small interfering RNA (siRNA) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 were administered intracerebroventricularly prior to COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, western blotting, and Fluoro-Jade C- and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed.

RESULTS

Endogenous TREM2 expression was increased and peaked at 24 h after ICH. TREM2 was expressed on microglia, astrocytes, and neurons. COG1410 improved both short-term and long-term neurological functions, reduced brain edema, inhibited microglia/macrophage activation and neutrophil infiltration, and suppressed neuronal apoptotic cell death in perihematomal areas after ICH. Knockdown of endogenous TREM2 by TREM2 siRNA aggravated neurological deficits and decreased the expression of TREM2 in naïve and ICH mice. COG1410 was associated with upregulation of TREM2, PI3K, phosphorylated-Akt, and Bcl-2 and downregulation of TNF-α, IL-1β, and Bax after ICH. The neuroprotective effects of COG1410 were abolished by both TREM2 siRNA and PI3K inhibitor LY294002.

CONCLUSIONS

Our finding demonstrated that TREM2 activation improved neurological functions and attenuated neuroinflammation and neuronal apoptosis after ICH, which was, at least in part, mediated by activation of PI3K/Akt signaling pathway. Therefore, activation of TREM2 may be a potential therapeutic strategy for the management of ICH patients.

Hydrochloride fasudil attenuates brain injury in ICH rats

Aim

The aim of this study was to investigate the neuroprotective effects of hydrochloride fasudil (HF) in rats following intracerebral hemorrhage (ICH).

Methods

Male Wistar rats were randomly divided into four groups: normal, sham-operated, ICH, and ICH/HF. ICH was induced by injection of non-anticoagulant autologous arterial blood into the right caudate nucleus. The levels of Rho-associated protein kinase 2 (ROCK2) mRNA and protein around the site of the hematoma were measured by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. The levels of interleukin-6 and tumor necrosis factor-α in serum were detected by ELISA. The inflammatory cells and changes in the neuronal morphology around the hematoma were visualized using hematoxylin and eosin and Nissl staining. Brain edema was measured by comparing wet and dry brain weights.

Results

Following ICH, the levels of ROCK2 were significantly increased from day 1 to day 7. The levels of ROCK2 were significantly lower in rats treated with HF than in controls. The levels of inflammatory cytokines and brain water content were significantly higher in rats treated with HF than in controls. Administration of HF significantly reduced the levels of inflammatory cytokines and brain water content from day 1 to day 7. In the acute phase of ICH, a large number of neutrophils infiltrated the perihematomal areas. In comparison with the ICH group, the ICH/HF group showed markedly fewer infiltrating neutrophils on day 1. Nissl staining showed that ICH caused neuronal death and loss of neurons in the perihematomal areas at all time points and that treatment with HF significantly attenuated neuronal loss.

Conclusions

HF exerts neuroprotective effects in ICH rats by inhibiting the expression of ROCK2, reducing neutrophil infiltration and production of inflammatory cytokines, decreasing brain edema, and attenuating loss of neurons.

Fully Automated Segmentation Algorithm for Perihematomal Edema Volumetry After Spontaneous Intracerebral Hemorrhage

Background and Purpose- Perihematomal edema (PHE) is a promising surrogate marker of secondary brain injury in patients with spontaneous intracerebral hemorrhage, but it can be challenging to accurately and rapidly quantify. The aims of this study are to derive and internally validate a fully automated segmentation algorithm for volumetric analysis of PHE. Methods- Inpatient computed tomography scans of 400 consecutive adults with spontaneous, supratentorial intracerebral hemorrhage enrolled in the Intracerebral Hemorrhage Outcomes Project (2009-2018) were separated into training (n=360) and test (n=40) datasets. A fully automated segmentation algorithm was derived from manual segmentations in the training dataset using convolutional neural networks, and its performance was compared with that of manual and semiautomated segmentation methods in the test dataset. Results- The mean volumetric dice similarity coefficients for the fully automated segmentation algorithm were 0.838±0.294 and 0.843±0.293 with manual and semiautomated segmentation methods as reference standards, respectively. PHE volumes derived from the fully automated versus manual (r=0.959; P<0.0001), fully automated versus semiautomated (r=0.960; P<0.0001), and semiautomated versus manual (r=0.961; P<0.0001) segmentation methods had strong between-group correlations. The fully automated segmentation algorithm (mean 18.0±1.8 seconds/scan) quantified PHE volumes at a significantly faster rate than both of the manual (mean 316.4±168.8 seconds/scan; P<0.0001) and semiautomated (mean 480.5±295.3 seconds/scan; P<0.0001) segmentation methods. Conclusions- The fully automated segmentation algorithm accurately quantified PHE volumes from computed tomography scans of supratentorial intracerebral hemorrhage patients with high fidelity and greater efficiency compared with manual and semiautomated segmentation methods. External validation of fully automated segmentation for assessment of PHE is warranted.

Spleen associated immune-response mediates brain-heart interaction after intracerebral hemorrhage

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) patients frequently encounter cardiovascular complications which may contribute to increased mortality and poor long term outcome. ICH induces systemic oxidative stress and activates peripheral immune responses which are involved in the pathological cascade leading to cardiac dysfunction and heart failure after ICH. We have previously reported that ICH induces progressive cardiac dysfunction in mice without primary cardiac diseases. In this study, we have investigated the role of immune response in mediating cardiac dysfunction post ICH in mice.

METHODS

Adult male C57BL/6 J mice were randomly assigned to the following groups (n = 8/group): 1) sham control; 2) ICH; 3) splenectomy with ICH (ICH + Spx); 4) splenectomy alone (Spx). Echocardiography was performed at 7 and 28 days after ICH. A battery of neurological and cognitive tests were performed. Flow cytometry, western blot and immunostaining were used to test mechanisms of ICH induced cardiac dysfunction.

RESULTS

Compared to sham control mice, Spx alone does not induce acute (7 day) or chronic (28 day) cardiac dysfunction. ICH induces significant neurological and cognitive deficits, as well as acute and chronic cardiac dysfunction compared to sham control mice. Mice subjected to ICH + Spx exhibit significantly improved neurological and cognitive function compared to ICH mice. Mice with ICH + Spx also exhibit significantly improved acute and chronic cardiac function compared to ICH mice indicated by increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), decreased cardiac fibrosis, decreased cardiomyocyte hypertrophy, decreased cardiac infiltration of immune cells and decreased expression of inflammatory factor and oxidative stress in the heart.

CONCLUSIONS

Our study demonstrates that splenectomy attenuates ICH-induced neurological and cognitive impairment as well as ICH-induced cardiac dysfunction in mice. Inflammatory cell infiltration into heart and immune responses mediated by the spleen may contribute to ICH-induce acute and chronic cardiac dysfunction and pathological cardiac remodeling.

Blood-Related Toxicity after Traumatic Brain Injury: Potential Targets for Neuroprotection

Emergency visits, hospitalizations, and deaths due to traumatic brain injury (TBI) have increased significantly over the past few decades. While the primary early brain trauma is highly deleterious to the brain, the secondary injury post-TBI is postulated to significantly impact mortality. The presence of blood, particularly hemoglobin, and its breakdown products and key binding proteins and receptors modulating their clearance may contribute significantly to toxicity. Heme, hemin, and iron, for example, cause membrane lipid peroxidation, generate reactive oxygen species, and sensitize cells to noxious stimuli resulting in edema, cell death, and increased morbidity and mortality. A wide range of other mechanisms such as the immune system play pivotal roles in mediating secondary injury. Effective scavenging of all of these pro-oxidant and pro-inflammatory metabolites as well as controlling maladaptive immune responses is essential for limiting toxicity and secondary injury. Hemoglobin metabolism is mediated by key molecules such as haptoglobin, heme oxygenase, hemopexin, and ferritin. Genetic variability and dysfunction affecting these pathways (e.g., haptoglobin and heme oxygenase expression) have been implicated in the difference in susceptibility of individual patients to toxicity and may be target pathways for potential therapeutic interventions in TBI. Ongoing collaborative efforts are required to decipher the complexities of blood-related toxicity in TBI with an overarching goal of providing effective treatment options to all patients with TBI.

Danger Signals in the ICU

OBJECTIVES

Sterile and infectious critical illnesses often result in vasoplegic shock and a robust systemic inflammatory response that are similar in presentation. The innate immune system is at the center of the response to both infectious and traumatic insults. Damage-associated molecular patterns are small molecules that are released from stressed or dying cells. Damage-associated molecular patterns activate pattern recognition receptors and coordinate the leading edge of the innate immune response. This review introduces the concept of damage-associated molecular patterns and how they activate a systemic inflammatory response, specifically in trauma, neurologic injury, and infection. It also explores how, when carried to extremes, damage-associated molecular patterns may even perpetuate multisystem organ failure.

DATA SOURCES

Basic and clinical studies were obtained from a PubMed search through August 2017.

STUDY SELECTION

Articles considered include original articles, review articles, and conference proceedings.

DATA EXTRACTION

An analysis of scientific, peer-reviewed data was performed. High quality preclinical and clinical studies adjudicated by the authors were included and summarized.

DATA SYNTHESIS

Pattern recognition receptors respond to damage-associated molecular patterns and then activate inflammatory pathways. Damage-associated molecular patterns have been linked to the recruitment of sentinel leukocytes and the initiation of the inflammatory cascade. Damage-associated molecular patterns have been linked to many conditions in critical care illnesses. Preclinical models have added insight into how they may mediate distant organ dysfunction.

CONCLUSIONS

Damage-associated molecular pattern activation and release is an important research for intensive care practitioners. It will add to our understanding of the phase and state of the innate immune response to an insult. Early work is encouraging. However, only with improved understanding of damage-associated molecular pattern activation and function, we can perhaps hope to target damage-associated molecular patterns as diagnostic and/or therapeutic modalities in the future.