The rise of soluble platelet-derived growth factor receptor β in CSF early after subarachnoid hemorrhage correlates with cerebral vasospasm

Elevated PDGF-BB from Bone Impairs Hippocampal Vasculature by Inducing PDGFRβ Shedding from Pericytes

Evidence suggests a unique association between bone aging and neurodegenerative/cerebrovascular disorders. However, the mechanisms underlying bone-brain interplay remain elusive. Here platelet-derived growth factor-BB (PDGF-BB) produced by preosteoclasts in bone is reported to promote age-associated hippocampal vascular impairment. Aberrantly elevated circulating PDGF-BB in aged mice and high-fat diet (HFD)-challenged mice correlates with capillary reduction, pericyte loss, and increased blood-brain barrier (BBB) permeability in their hippocampus. Preosteoclast-specific Pdgfb transgenic mice with markedly high plasma PDGF-BB concentration faithfully recapitulate the age-associated hippocampal BBB impairment and cognitive decline. Conversely, preosteoclast-specific Pdgfb knockout mice have attenuated hippocampal BBB impairment in aged mice or HFD-challenged mice. Persistent exposure of brain pericytes to high concentrations of PDGF-BB upregulates matrix metalloproteinase 14 (MMP14), which promotes ectodomain shedding of PDGF receptor β (PDGFRβ) from pericyte surface. MMP inhibitor treatment alleviates hippocampal pericyte loss and capillary reduction in the conditional Pdgfb transgenic mice and antagonizes BBB leakage in aged mice. The findings establish the role of bone-derived PDGF-BB in mediating hippocampal BBB disruption and identify the ligand-induced PDGFRβ shedding as a feedback mechanism for age-associated PDGFRβ downregulation and the consequent pericyte loss.

Peroxiredoxin 2 Is a Potential Objective Indicator for Severity and the Clinical Status of Subarachnoid Hemorrhage Patients

Purpose

We have demonstrated that peroxiredoxin 2 (Prx2) released from lytic erythrocytes and damaged neurons into the subarachnoid space could activate microglia and then result in neuronal apoptosis. In this study, we tested the possibility of using Prx2 as an objective indicator for severity of the subarachnoid hemorrhage (SAH) and the clinical status of the patient.

Materials and Methods

SAH patients were prospectively enrolled and followed up for 3 months. Cerebrospinal fluid (CSF) and blood samples were collected 0-3 and 5-7 days after SAH onset. The levels of Prx2 in the CSF and the blood were measured by an enzyme-linked immunosorbent assay (ELISA). We used Spearman's rank coefficient to assess the correlation between Prx2 and the clinical scores. Receiver operating characteristic (ROC) curves were used for Prx2 levels to predict the outcome of SAH by calculating the area under the curve (AUC). Unpaired Student's t-test was used to analyze the differences in continuous variables across cohorts.

Results

Prx2 levels in the CSF increased after onset while those in the blood decreased. Existing data showed that Prx2 levels within 3 days in the CSF after SAH were positively correlated with the Hunt-Hess score (R = 0.761, P < 0.001). Patients with CVS had higher levels of Prx2 in their CSF within 5-7 days after onset. Prx2 levels in the CSF within 5-7 days can be used as a predictor of prognosis. The ratio of Prx2 in the CSF and the blood within 3 days of onset was positively correlated with the Hunt-Hess score and negatively correlated with Glasgow Outcome Scale (GOS; R = -0.605, P < 0.05).

Conclusion

We found that the levels of Prx2 in the CSF and the ratio of Prx2 in the CSF and the blood within 3 days of onset can be used as a biomarker to detect the severity of the disease and the clinical status of the patient.

The mechanism and relevant mediators associated with neuronal apoptosis and potential therapeutic targets in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a dominant cause of death and disability worldwide. A sharp increase in intracranial pressure after SAH leads to a reduction in cerebral perfusion and insufficient blood supply for neurons, which subsequently promotes a series of pathophysiological responses leading to neuronal death. Many previous experimental studies have reported that excitotoxicity, mitochondrial death pathways, the release of free radicals, protein misfolding, apoptosis, necrosis, autophagy, and inflammation are involved solely or in combination in this disorder. Among them, irreversible neuronal apoptosis plays a key role in both short- and long-term prognoses after SAH. Neuronal apoptosis occurs through multiple pathways including extrinsic, mitochondrial, endoplasmic reticulum, p53 and oxidative stress. Meanwhile, a large number of blood contents enter the subarachnoid space after SAH, and the secondary metabolites, including oxygenated hemoglobin and heme, further aggravate the destruction of the blood-brain barrier and vasogenic and cytotoxic brain edema, causing early brain injury and delayed cerebral ischemia, and ultimately increasing neuronal apoptosis. Even there is no clear and effective therapeutic strategy for SAH thus far, but by understanding apoptosis, we might excavate new ideas and approaches, as targeting the upstream and downstream molecules of apoptosis-related pathways shows promise in the treatment of SAH. In this review, we summarize the existing evidence on molecules and related drugs or molecules involved in the apoptotic pathway after SAH, which provides a possible target or new strategy for the treatment of SAH.

Decreased Expression of CIRP Induced by Therapeutic Hypothermia Correlates with Reduced Early Brain Injury after Subarachnoid Hemorrhage

Early brain injury is considered to be a primary reason for the poor prognosis of patients suffering from subarachnoid hemorrhage (SAH). Due to its pro-inflammatory activity, cold-inducible RNA-binding protein (CIRP) has been implicated in the ischemic brain insult, but its possible interplay with hypothermia in SAH treatment remains to be evaluated. One-hundred and thirty-eight Sprague-Dawley rats (300–350 g males) were randomly allocated into the following groups: sham-operated (Sham); SAH; and SAH + hypothermia (SAH + H), each comprised of 46 animals. After treatments, the brain tissues of the three groups were randomly collected after 12 h, 1 d, 3 d, and 7 d, and the expression levels of the CIRP and mitochondrial apoptosis pathway-related proteins Bax, Bcl-2, caspase-9, caspase-3, and cytochrome c measured using Western blotting and real-time PCR. Brain damage was assessed by TUNEL and Nissl staining, the electron microscopy of brain tissue slices as well as functional rotarod tests. Expression of CIRP, Bax, caspase-9, caspase-3, and cytochrome c as well as reduced motor function incidence were higher in the SAH group, particularly during the first 3 d after SAH induction. Hypothermia blunted these SAH responses and apoptosis, thereby indicating reduced inflammatory signaling and less brain cell injury in the early period after SAH. Hypothermia treatment was found to effectively protect the brain tissue from early SAH injury in a rat model and its further evaluation as a therapeutic modality in SAH patients requires further study.

Role of Dexmedetomidine in Aneurysmal Subarachnoid Hemorrhage: A Comprehensive Scoping Review

Dexmedetomidine (DEX), an α2-adrenergic agonist, has been widely used for anesthesia, pain control, and intensive care unit sedation. Besides sleep-like sedation, DEX has many other beneficial effects, such as anti-inflammation, antioxidation, and anticell death. Subarachnoid hemorrhage (SAH), a severe and potentially fatal form of stroke, is a complex disease that is divided into 2 phases: early brain injury and delayed cerebral ischemia. In each phase, several pathologic changes are involved, including disturbed intracranial homeostasis, metabolic failure, blood-brain barrier damage, vasospasm, microthrombosis, and cortical spreading depolarization. DEX has been shown to have an effect on these SAH-related pathologic processes. Research shows that DEX could serve as a protective therapy for patients with SAH due to its ability to maintain stable intracerebral homeostasis, balance coagulation-fibrinolysis, repair a damaged blood-brain barrier as well as prevent vasospasm and suppress cortical spreading depolarization by anti-inflammatory, antioxidative, antiapoptotic, and vasoconstriction-dilation effects. In this scoping review, we critically assess the existing data on the potential protective effect of DEX after SAH. So far, only 1 retrospective clinical trial assessing the effect of DEX on clinical outcomes after SAH has been performed. Hence, more trials are still needed as well as translational research bringing results from bench to bedside.

Vasospasm: Role of Imaging in Detection and Monitoring Treatment

Cerebral vasospasm (VS) and delayed cerebral ischemia (DCI) are important complications of aneurysmal subarachnoid hemorrhage (ASAH). Imaging approaches to VS monitoring include noninvasive bedside assessment with transcranial Doppler ultrasonography, angiographic evaluation with digital subtraction angiography, and computed tomography (CT) angiography. DCI is a clinical diagnosis and is not fully explained by the presence of angiographic VS. CT perfusion has shown clinical utility and implications for future research in the evaluation of DCI in patients with ASAH. This review article discusses the common approaches to diagnosis and monitoring of VS and DCI, current treatment strategies, and future research directions.

Evaluation of serum platelet-derived growth factor receptor-ß and brain-derived neurotrophic factor levels in microvascular angina

Objective:

Microvascular angina (MVA) is a coronary microcirculation disease. Research on microcirculatory dysfunction has revealed several biomarkers involved in the etiopathogenesis of MVA. Platelet-derived growth factor receptor β (PDGFR-β) and brain-derived neurotrophic factor (BDNF) are 2 biomarkers associated with microcirculation, particularly pericytes function. The aim of this study was to investigate the role of PDGFR-β and BDNF in MVA.

Methods:

Ninety-one patients (median age, 56 y; age range, 40–79 y; 36 men) with MVA and 61 control group subjects (median age, 52 y; age range, 38–76 y; 29 men) were included in the study. Serum concentrations of PDGFR-β and BDNF were measured with commercially available enzyme-linked immunosorbent assay kits.

Results:

PDGFR-β [2.82 ng/ml; interquartile range (IQR), 0.57–7.79 ng/ml vs. 2.27 ng/ml; IQR, 0.41–7.16 ng/ml; p<0.0005] and BDNF (2.41 ng/ml; IQR, 0.97–7.97 ng/ml vs. 1.92 ng/ml; IQR, 1.07–6.67 ng/ml; p=0.023) concentrations were significantly higher in patients with MVA compared with the controls. PDGFR-β correlated positively with age (r=0.26, p=0.001), low-density lipoprotein (r=0.18; p=0.02), and BDNF (r=0.47; p<0.001), and BDNF showed a significant positive correlation with age (r=0.20; p=0.01). In binary logistic regression analysis, high-sensitivity C-reactive protein, uric acid, and PDGFR-β values were found to be independent predictors of MVA.

Conclusion:

MVA is associated with higher PDGFR-β and BDNF levels. This association may indicate an abnormality in microvascular function. Future studies are required to determine the role of these biomarkers in the pathogenesis of MVA. (Anatol J Cardiol 2020; 24: 397-404)