Irreversible Neuronal Damage Begins Just After Aneurysm Rupture in Poor-Grade Subarachnoid Hemorrhage Patients

Dental pulp mesenchymal stem cell-derived exosomes inhibit neuroinflammation and microglial pyroptosis in subarachnoid hemorrhage via the miRNA-197-3p/FOXO3 axis

BACKGROUND

Subarachnoid hemorrhage (SAH) is a severe stroke subtype that lacks effective treatment. Exosomes derived from human dental pulp stem cells (DPSCs) are a promising acellular therapeutic strategy for neurological diseases. However, the therapeutic effects of DPSC-derived exosomes (DPSC-Exos) on SAH remain unknown. In this study, we investigated the therapeutic effects and mechanisms of action of DPSC-Exos in SAH.

MATERIALS AND METHODS

SAH was established using 120 male Sprague-Dawley rats. One hour after SAH induction, DPSC-Exos were administered via tail vein injection. To investigate the effect of DPSC-Exos, SAH grading, short-term and long-term neurobehavioral assessments, brain water content, western blot (WB), immunofluorescence staining, Nissl staining, and HE staining were performed. The role of miR-197-3p/FOXO3 in regulating pyroptosis was demonstrated through miRNA sequencing, bioinformatics analysis, and rescue experiments. The SAH model in vitro was established by stimulating BV2 cells with hemoglobin (Hb) and the underlying mechanism of DPSC-Exos was investigated through WB and Hoechst/PI staining.

RESULTS

The expressions of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) were increased after SAH. DPSC-Exos alleviated brain edema and neuroinflammation by inhibiting the expression of FOXO3 and reducing NLRP3 inflammasome activation, leading to improved neurobehavioral functions at 24 h after SAH. In vitro, the expression of the NLRP3 inflammasome components (NLRP3 and caspase1-p20), GSDMD-N, and IL-18 was inhibited in BV2 cells pretreated with DPSC-Exos. Importantly, DPSC-Exos overexpressing miR-197-3p had a more obvious protective effect than those from NC-transfected DPSCs, while those from DPSCs transfected with the miR-197-3p inhibitor had a weaker protective effect. Functional studies indicated that miR-197-3p bound to the 3'-untranslated region of FOXO3, inhibiting its transcription. Furthermore, the overexpression of FOXO3 reversed the protective effects of miR-197-3p.

CONCLUSIONS

DPSC-Exos inhibited activation of the NLRP3 inflammasome and related cytokine release via the miR-197-3p/FOXO3 pathway, alleviated neuroinflammation, and inhibited microglial pyroptosis. These findings suggest that using DPSC-Exos is a promising therapeutic strategy for SAH.

Impact of Race on Outcomes in the Endovascular and Microsurgical Treatment in Patients With Intracranial Aneurysms

BACKGROUND AND OBJECTIVES

The impact of race on outcomes in the treatment of intracranial aneurysm (IA) remains unclear. We aimed to investigate the relationship between race classified into White, Black, Hispanic, and other and treatment outcomes in patients with ruptured and unruptured IAs.

METHODS

The study population consisted of 2836 patients with IA with endovascular treatment or microsurgical treatment (MST) from 16 centers in the United States and Asia, all participating in the observational "STAR" registry. The primary outcome was a 90-day modified Rankin Scale of 0 to 2. Secondary outcomes included periprocedural cerebral infarction and intracranial hemorrhage, perioperative symptomatic cerebral vasospasm in ruptured IA and mortality, and all causes of mortality within 90 days.

RESULTS

One thousand fifty-three patients were White (37.1%), 350 were Black (12.3%), 264 were Hispanic (9.3%), and 1169 were other (41.2%). Compared with White patients, Hispanic patients had a significantly lower proportion of primary outcome (adjusted odds ratio [aOR] 0.36, 95% CI, 0.23-0.56) and higher proportion of the periprocedural cerebral infarction, perioperative mortality, and all causes of mortality (aOR 2.53, 95% CI, 1.40-4.58, aOR 1.84, 95% CI, 1.00-3.38, aOR 1.83, 95% CI, 1.06-3.17, respectively). Outcomes were not significantly different in Black and other patients. The subgroup analysis showed that Hispanic patients with age ≥65 years (aOR 0.19, 95% CI, 0.10-0.38, interaction P = .048), Hunt-Hess grades 0 to 3 (aOR 0.29, 95% CI, 0.19-0.46, interaction P = .03), and MST (aOR 0.24, 95% CI, 0.13-0.44, interaction P = .04) had a significantly low proportion of primary outcome.

CONCLUSION

This study demonstrates that Hispanic patients with IA are more likely to have a poor outcome at 90 days after endovascular treatment or MST than White patients. Physicians have to pay attention to the selection of treatment modalities, especially for Hispanic patients with specific factors to reduce racial discrepancies.

Neurobehavioral Impairments Predict Specific Cerebral Damage in Rat Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a severe form of stroke that can cause unpredictable and diffuse cerebral damage, which is difficult to detect until it becomes irreversible. Therefore, there is a need for a reliable method to identify dysfunctional regions and initiate treatment before permanent damage occurs. Neurobehavioral assessments have been suggested as a possible tool to detect and approximately localize dysfunctional cerebral regions. In this study, we hypothesized that a neurobehavioral assessment battery could be a sensitive and specific method for detecting damage in discrete cerebral regions following SAH. To test this hypothesis, a behavioral battery was employed at multiple time points after SAH induced via an endovascular perforation, and brain damage was confirmed via postmortem histopathological analysis. Our results demonstrate that impairment of sensorimotor function accurately predict damage in the cerebral cortex (AUC 0.905; sensitivity 81.8%; specificity 90.9%) and striatum (AUC 0.913; sensitivity 90.1%; specificity 100%), while impaired novel object recognition is a more accurate indicator of damage to the hippocampus (AUC 0.902; sensitivity 74.1%; specificity 83.3%) than impaired reference memory (AUC 0.746; sensitivity 72.2%; specificity 58.0%). Tests for anxiety-like and depression-like behaviors predict damage to the amygdala (AUC 0.900; sensitivity 77.0%; specificity 81.7%) and thalamus (AUC 0.963; sensitivity 86.3%; specificity 87.8%), respectively. This study suggests that recurring behavioral testing can accurately predict damage in specific brain regions, which could be developed into a clinical battery for early detection of SAH damage in humans, potentially improving early treatment and outcomes.

Neurobehavioral impairments predict specific cerebral damage in rat model of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a severe form of stroke that can cause unpredictable and diffuse cerebral damage, which is difficult to detect until it becomes irreversible. Therefore, there is a need for a reliable method to identify dysfunctional regions and initiate treatment before permanent damage occurs. Neurobehavioral assessments have been suggested as a possible tool to detect and approximately localize dysfunctional cerebral regions. In this study, we hypothesized that a neurobehavioral assessment battery could be a sensitive and specific early warning for damage in discrete cerebral regions following SAH. To test this hypothesis, a behavioral battery was employed at multiple time points after SAH induced via an endovascular perforation, and brain damage was confirmed via postmortem histopathological analysis. Our results demonstrate that impairment of sensorimotor function accurately predict damage in the cerebral cortex (AUC: 0.905; sensitivity: 81.8%; specificity: 90.9%) and striatum (AUC: 0.913; sensitivity: 90.1%; specificity: 100%), while impaired novel object recognition is a more accurate indicator of damage to the hippocampus (AUC: 0.902; sensitivity: 74.1%; specificity: 83.3%) than impaired reference memory (AUC: 0.746; sensitivity: 72.2%; specificity: 58.0%). Tests for anxiety-like and depression-like behaviors predict damage to the amygdala (AUC: 0.900; sensitivity: 77.0%; specificity: 81.7%) and thalamus (AUC: 0.963; sensitivity: 86.3%; specificity: 87.8%), respectively. This study suggests that recurring behavioral testing can accurately predict damage in specific brain regions, which could be developed into a clinical battery for early detection of SAH damage in humans, potentially improving early treatment and outcomes.

Emergent Subarachnoid Clot Removal with Aneurysm Repair for Subarachnoid Hemorrhage Might Improves Clinical Outcome

BACKGROUND

The goal in treating patients with subarachnoid hemorrhage (SAH) is shifting to preventing early brain injury. Intracranial pressure must be controlled to manage such an injury. We retrospectively analyzed the impact of aggressive removal of cisternal subarachnoid clots with simultaneous aneurysm repair for all grades of SAH.

METHODS

Our study included 260 consecutive patients with SAH treated through aggressive subarachnoid clot removal with simultaneous aneurysm repair. Baseline patient characteristics, history, radiographic findings, and time of SAH onset to arrival in the operating room were retrospectively collected. Factors related to poor outcome (modified Rankin Scale score >2) were analyzed.

RESULTS

Multivariate analysis revealed several characteristics were significantly associated with poor outcome: advanced age (adjusted odds ratio [aOR] 1.07, 95% confidence interval [CI] 1.04-01.10); time of SAH onset to operating room per 1-hour increments (aOR 1.03, 95% CI 1.01-01.05; postoperative hematoma volume (aOR 1.04, 95% CI 1.01-01.06); and poorer World Federation of Neurosurgical Societies grade (aOR 2.18, 95% CI 1.63-02.92). According to a receiver operating characteristic analysis, the cut-off time of SAH onset to operating room was 6.0 hours (area under the curve 0.61, P = 0.01, 95% CI 0.52-0.69, sensitivity = 0.79, specificity = 0.43) as the threshold between modified Rankin Scale scores of 0-2 and 3-6.

CONCLUSIONS

Prognostic factors of SAH in patients undergoing emergent aneurysm repair with simultaneous removal of a cisternal subarachnoid clot are advanced age, poorer World Federation of Neurosurgical Societies grade, postoperative hematoma volume, and a longer time from SAH onset to operating room. The clinical outcome may improve with emergent reduction of intracranial pressure through removal of the subarachnoid clot as soon as possible.

Roles of Rufy3 in experimental subarachnoid hemorrhage-induced early brain injury via accelerating neuronal axon repair and synaptic plasticity

RUN and FYVE domain-containing 3 (Rufy3) is a well-known adapter protein of a small GTPase protein family and is bound to the activated Ras family protein to maintain neuronal polarity. However, in experimental subarachnoid hemorrhage (SAH), the role of Rufy3 has not been investigated. Consequently, we aimed to investigate the potential role of Rufy3 in an in vivo model of SAH-induced early brain injury (EBI). In addition, we investigated the relevant brain-protective mechanisms. Oxyhemoglobin (OxyHb) stimulation of cultured primary neurons simulated vitro SAH condition. The SAH rat model was induced by infusing autologous blood into the optic chiasma pool and treating the rats with lentivirus-negative control 1 (LV-NC1), lentivirus-Rufy3 shRNA (LV-shRNA), lentivirus-negative control 2 (LV-NC2), lentivirus-Rufy3 (LV-Rufy3), or 8-pCPT-2′-O-Me-cAMP (8p-CPT) (Rap1 agonist). In experiment one, we found that the protein level of Rufy3 decreased and neuronal axon injury in the injured neurons but was rectified by LV-Rufy3 treatment. In experiment two, mRNA and protein levels of Rufy3 were downregulated in brain tissue and reached the lowest level at 24 h after SAH. In addition, the expression of Myelin Basic Protein was downregulated and that of anti-hypophosphorylated neurofilament H (N52) was upregulated after SAH. In experiments three and four, Rufy3 overexpression (LV-Rufy3) increased the interactions between Rufy3 and Rap1, the level of Rap1-GTP, and the ratio of Rap1-GTP/total GTP. In addition, LV-Rufy3 treatment inhibited axon injury and accelerated axon repair by activating the Rap1/Arap3/Rho/Fascin signaling pathway accompanied by upregulated protein expression levels of ARAP3, Rho, Fascin, and Facin. LV-Rufy3 also enhanced synaptic plasticity by activating the Rap1/MEK/ERK/synapsin I signaling pathway accompanied by upregulated protein expression levels of ERK1, p-ERK1, MEK1, p-MEK1, synaspin I, and p-synaspin I. Moreover, LV-Rufy3 also alleviated brain damage indicators, including cortical neuronal cell apoptosis and degeneration, brain edema, and cognitive impairment after SAH. However, the downregulation of Rufy3 had the opposite effect and aggravated EBI induced by SAH. Notably, the combined application of LV-Rufy3 and 8p-CPT showed a significant synergistic effect on the aforementioned parameters. Our findings suggest that enhanced Rufy3 expression may reduce EBI by inhibiting axon injury and promoting neuronal axon repair and synaptic plasticity after SAH.

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.