Therapeutically Targeting Platelet-Derived Growth Factor-Mediated Signaling Underlying the Pathogenesis of Subarachnoid Hemorrhage-Related Vasospasm

Neuroinflammatory response after subarachnoid hemorrhage: A review of possible treatment targets

A serious neurosurgical emergency, subarachnoid hemorrhage (SAH) is characterized by vascular and neuropathy, as well as complex pathological mechanisms like vascular lesions, inflammatory responses, and nerve cell damage. The inflammatory response is an essential aspect of SAH's pathophysiology, causing the release of a number of inflammatory mediators and oxidative stress products like TNF-α, MCP-1, MMPs, and so on, which either directly or indirectly contribute to the development of SAH.It has recently been discovered that some antibodies against inflammatory mediators, antioxidant stress, botanicals, and traditional Chinese medicine decrease the inflammatory response of SAH. Additionally, certain biomarkers linked to inflammation may serve as a foundation for clinical diagnosis.Although these mechanisms are still not completely understood, we can explore potential therapeutic targets by studying the role of inflammatory responses and bioactive molecules in the formation of SAH.

Impact of human serum albumin level on symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

To investigate the impact of human serum albumin (HSA) levels on symptomatic cerebral vasospasm (SCVS) in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

We retrospectively reviewed the medical records. SCVS was defined as the development of a new neurological deterioration when the cause was considered to be ischemia attributable to vasospasm after other possible causes of worsening had been excluded. The aSAH patients were divided into two groups: those with SCVS (group 1) and those without SCVS (group 2). The HSA level data on the 1st, 2nd, and 3rd day after admission was collected. Multivariate logistical regression and receiver operating characteristic (ROC) analysis were performed to evaluate the ability of HSA level to predict the development of SCVS.

RESULTS

A total of 270 patients were included in our study, of which 74 (27.4%) developed SCVS. The average and lowest HSA levels were lower in group 1 (P < 0.001). In univariate logistic regression, white blood cell count, neutrophil count, and average and lowest HSA levels were associated with SCVS. After adjustment for age, CT Fisher grade, Hunt-Hess grade, and WFNS grade, both the average and lowest HSA levels remained independent predictors of SCVS (P < 0.001). The CT Fisher grade was confirmed to be an independent predictor of SCVS across each model. ROC analysis revealed that the lowest HSA level was a better predictor for SCVS than average HSA level and CT Fisher grade.

CONCLUSION

Clinicians are encouraged to measure HSA levels for the first 3 days after admission to predict the occurrence of SCVS after aSAH.

Immunological Profile of Vasospasm after Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) carries high mortality and disability rates, which are substantially driven by complications. Early brain injury and vasospasm can happen after SAH and are crucial events to prevent and treat to improve prognosis. In recent decades, immunological mechanisms have been implicated in SAH complications, with both innate and adaptive immunity involved in mechanisms of damage after SAH. The purpose of this review is to summarize the immunological profile of vasospasm, highlighting the potential implementation of biomarkers for its prediction and management. Overall, the kinetics of central nervous system (CNS) immune invasion and soluble factors' production critically differs between patients developing vasospasm compared to those not experiencing this complication. In particular, in people developing vasospasm, a neutrophil increase develops in the first minutes to days and pairs with a mild depletion of CD45+ lymphocytes. Cytokine production is boosted early on after SAH, and a steep increase in interleukin-6, metalloproteinase-9 and vascular endothelial growth factor (VEGF) anticipates the development of vasospasm after SAH. We also highlight the role of microglia and the potential influence of genetic polymorphism in the development of vasospasm and SAH-related complications.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

Poor expression of miR-195-5p can assist the diagnosis of cerebral vasospasm after subarachnoid hemorrhage and predict adverse outcomes

OBJECTIVE

Patients with spontaneous subarachnoid hemorrhage (SAH) may develop refractory arterial cerebral vasospasm (CVS), which is the leading cause of death in SAH patients. This study explored the clinical diagnostic value of serum miR-195-5p levels in CVS after SAH (SAH + CVS) and its relationship with the prognosis of SAH + CVS.

METHODS

A total of 110 patients with spontaneous SAH were divided into the SAH group (N = 62) and SAH + CVS group (N = 58), with 60 healthy subjects as controls. The clinical data of blood glucose, blood sodium fluctuation, and serum lactic acid were recorded. miR-195-5p serum level was detected by RT-qPCR and its diagnostic value on SAH + CVS was analyzed by receiver operating characteristic curve. Serum levels of PDGF/IL-6/ET-1 and their correlation with miR-195-5p were analyzed using RT-qPCR, enzyme-linked immunosorbent assay, and Pearson's method. The patient prognosis was evaluated by Glasgow Outcome Scale. The effect of miR-195-5p levels on adverse prognosis was analyzed by Kaplan-Meier method and Cox regression analysis.

RESULTS

miR-195-5p was lowly expressed in the serum of SAH patients and lower in SAH + CVS patients. Serum miR-195-5p level assisted the diagnosis of SAH and SAH + CVS and was negatively correlated with PDGF/IL-6/ET-1 levels and was an independent risk factor together with ET-1 and blood glucose for SAH + CVS. miR-195-5p low expression predicted a higher cumulative incidence of adverse outcomes and was an independent predictor of adverse outcomes.

CONCLUSION

Poor expression of miR-195-5p can assist the diagnosis of SAH + CVS and predict higher adverse outcomes.

Al-buhadiliy A, De Waard M, Sabatier JM, Khan Khalil AA, Saad HM, Batiha GES. Role of Neuropilin 1 in COVID-19 Patients with Acute Ischemic Stroke

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection can trigger the adaptive and innate immune responses, leading to uncontrolled inflammatory reactions and associated local and systematic tissue damage, along with thromboembolic disorders that may increase the risk of acute ischemic stroke (AIS) in COVID-19 patients. The neuropilin (NRP-1) which is a co-receptor for the vascular endothelial growth factor (VEGF), integrins, and plexins, is involved in the pathogenesis of AIS. NRP-1 is also regarded as a co-receptor for the entry of SARS-CoV-2 and facilitates its entry into the brain through the olfactory epithelium. NRP-1 is regarded as a cofactor for binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2), since the absence of ACE2 reduces SARS-CoV-2 infectivity even in presence of NRP-1. Therefore, the aim of the present study was to clarify the potential role of NRP-1 in COVID-19 patients with AIS. SARS-CoV-2 may transmit to the brain through NRP-1 in the olfactory epithelium of the nasal cavity, leading to different neurological disorders, and therefore about 45% of COVID-19 patients had neurological manifestations. NRP-1 has the potential capability to attenuate neuroinflammation, blood-brain barrier (BBB) permeability, cerebral endothelial dysfunction (ED), and neuronal dysfunction that are uncommon in COVID-19 with neurological involvement, including AIS. Similarly, high NRP-1 serum level is linked with ED, oxidative stress, and the risk of pulmonary thrombosis in patients with severe COVID-19, suggesting a compensatory mechanism to overcome immuno-inflammatory disorders. In conclusion, NRP-1 has an important role in the pathogenesis of COVID-19 and AIS, and could be the potential biomarker linking the development of AIS in COVID-19. The present findings cannot provide a final conclusion, and thus in silico, experimental, in vitro, in vivo, preclinical, and clinical studies are recommended to confirm the potential role of NRP-1 in COVID-19, and to elucidate the pharmacological role of NRP-1 receptor agonists and antagonists in COVID-19.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Nafamostat protects against early brain injury after subarachnoid hemorrhage in mice

This study aimed to evaluate the effects of nafamostat, a serin protease inhibitor, in the management of subarachnoid hemorrhage (SAH). SAH was induced by endovascular perforation in male mice. Nafamostat was administered intraperitoneally four times immediately after SAH induction. Cerebral blood flow, neurological behavior tests, SAH grade and protein expression were evaluated at 24 h after SAH induction. In the in vitro model, human brain microvascular endothelial cells (HBMVECs), HBVECs were exposed to thrombin and hypoxia for 24 h; nafamostat was administered and the protein expression was evaluated. Eighty-eight mice were included in the in vivo study. Fifteen mice (17%) were excluded because of death or procedure failure. Nafamostat exerted no significant effect on the SAH grade or cerebral blood flow; however, it improved the neurological behavior and suppressed the thrombin and MMP-9 expression. In addition, nafamostat suppressed the ICAM-1 expression and p38 phosphorylation in the in vitro study. Nafamostat has a protective effect against HBMVEC after exposure to thrombin and hypoxia, suggesting its role in improving the neurological outcomes after SAH. These findings indicate that nafamostat has the potential to be a novel therapeutic drug in the management of SAH.

Role of platelets in the pathogenesis of delayed injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) patients develop delayed cerebral ischemia and delayed deficits (DCI) within 2 weeks of aneurysm rupture at a rate of approximately 30%. DCI is a major contributor to morbidity and mortality after SAH. The cause of DCI is multi-factorial with contributions from microthrombi, blood vessel constriction, inflammation, and cortical spreading depolarizations. Platelets play central roles in hemostasis, inflammation, and vascular function. Within this review, we examine the potential roles of platelets in microthrombi formation, large artery vasospasm, microvessel constriction, inflammation, and cortical spreading depolarization. Evidence from experimental and clinical studies is provided to support the role(s) of platelets in each pathophysiology which contributes to DCI. The review concludes with a suggestion for future therapeutic targets to prevent DCI after aSAH.

Systemic immune-inflammation index predicts the outcome after aneurysmal subarachnoid hemorrhage

Systemic inflammatory response is closely related to the pathogenesis and prognosis in critical patients. Recently, systemic immune-inflammation index (SII), an indicator of systemic inflammatory response, was proved to predict the outcome in cancerous and non-cancerous diseases. The aim of this study is to investigate the association between SII on admission and 6-month outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). The clinical data and prognosis of 76 patients with aSAH were analyzed. The 6-month outcome was assessed by the modified Rankin scale(mRS). The unfavorable outcome was defined as mRS score ≥ 3. In addition, multivariate analysis was conducted to investigate factors independently associated with the favorable outcome. Receiver operating characteristic (ROC) curve analysis was undertaken to identify the best cut-off value of SII for the discriminate between favorable and unfavorable outcome in these patients. Thirty-six patients (47.4%) in our study had an unfavorable outcome (mRS ≥ 3) at 6 months, and twenty-four (66.7%) of them were in the high-SII group. A significantly higher SII on admission was observed in patients with unfavorable functional outcome at 6 months. Binary logistic regression analysis showed that there was an independent association between SII on admission and 6-month clinical outcome (adjusted OR = 4.499, 95%CI: 1.242-16.295, P < 0.05). The AUC of the SII for predicting unfavorable outcome was 0.692 (95% CI: 0.571-0.814, P < 0.05). Systemic immune-inflammation index (SII) could be a novel independent prognostic factor for aSAH patients at the early stage of the disease.

The Pathogenesis of Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) and reportedly contributes to poor neurological outcomes. In this review, we summarize the molecular and cellular mechanisms involved in the pathogenesis of hydrocephalus following aSAH and summarize its treatment strategies. Various mechanisms have been implicated for the development of chronic hydrocephalus following aSAH, including alterations in cerebral spinal fluid (CSF) dynamics, obstruction of the arachnoid granulations by blood products, and adhesions within the ventricular system. Regarding molecular mechanisms that cause chronic hydrocephalus following aSAH, we carried out an extensive review of animal studies and clinical trials about the transforming growth factor-β/SMAD signaling pathway, upregulation of tenascin-C, inflammation-dependent hypersecretion of CSF, systemic inflammatory response syndrome, and immune dysregulation. To identify the ideal treatment strategy, we discuss the predictive factors of shunt-dependent hydrocephalus between surgical clipping and endovascular coiling groups. The efficacy and safety of other surgical interventions including the endoscopic removal of an intraventricular hemorrhage, placement of an external ventricular drain, the use of intraventricular or cisternal fibrinolysis, and an endoscopic third ventriculostomy on shunt dependency following aSAH were also assessed. However, the optimal treatment is still controversial, and it necessitates further investigations. A better understanding of the pathogenesis of acute and chronic hydrocephalus following aSAH would facilitate the development of treatments and improve the outcome.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.