Early release of high-mobility group box 1 (HMGB1) from neurons in experimental subarachnoid hemorrhage in vivo and in vitro.

BACKGROUND: Translocation of high-mobility group box 1 (HMGB1) from nucleus could trigger inflammation. Extracellular HMGB1 up-regulates inflammatory response in sepsis as a late mediator. However, little was known about its role in subarachnoid hemorrhage-inducible inflammation, especially in the early stage. This study aims to identify whether HMGB1 translocation occurred early after SAH and also to clarify the potential role of HMGB1 in brain injury following SAH. METHODS: Sprague-Dawley (SD) rats were randomly divided into sham group and SAH groups at 2 h, 12 h and on day 1, day 2. SAH groups suffered experimental subarachnoid hemorrhage by injection of 0.3 ml autoblood into the pre-chiasmatic cistern. Rats injected by recombinant HMGB1(rHMGB1) solution were divided into four groups according to different time points. Cultured neurons were assigned into control group and four hemoglobin (Hb) incubated groups. Mixed glial cells were cultured and stimulated in medium from neurons incubated by Hb. HMGB1 expression is measured by western blot analysis, real-time polymerase chain reaction (PCR), immunohistochemistry and immunofluorescence. Downstream nuclear factor kappa B (NF-κB) subunit P65 and inflammatory factor Interleukin 1ß (IL-1ß) were measured by western blot and real-time PCR, respectively. Brain injury was evaluated by cleaved caspase-3 staining. RESULTS: Our results demonstrated HMGB1 translocation occurred as early as 2 h after experimental SAH with mRNA and protein level increased. Immunohistochemistry and immunofluorescence results indicated cytosolic HMGB1 was mainly located in neurons while translocated HMGB1 could also be found in some microglia. After subarachnoid injection of rHMGB1, NF-κB, downstream inflammatory response and cleaved caspase-3 were up-regulated in the cortex compared to the saline control group. In-vitro, after Hb incubation, HMGB1 was also rapidly released from neurons to medium. Incubation with medium from neurons up-regulated IL-1ß in mixed glial cells. This effect could be inhibited by HMGB1 specific inhibitor glycyrrhizic acid (GA) treatment. CONCLUSION: HMGB1 was released from neurons early after SAH onset and might trigger inflammation as an upstream inflammatory mediator. Extracellular HMGB1 contributed to the brain injury after SAH. These results might have important implications during the administration of specific HMGB1 antagonists early in order to prevent or reduce inflammatory response following SAH.

Biphasic activation of nuclear factor kappa B and expression of p65 and c-Rel after traumatic brain injury in rats.

BACKGROUND AND OBJECT: Nuclear factor kappa B (NF-κB) functions as a key regulator in the central nervous system and regulates the inflammatory pathway. There are two peaks of cerebral NF-κB activation after neonatal hypoxia-ischemia and subarachnoid hemorrhage. Our previous studies found that NF-κB activity was up-regulated at an early stage and remained elevated at day 7 after traumatic brain injury (TBI). However, data are lacking regarding an overview of NF-κB activity and expression of NF-κB subunits after TBI. Hence, the current study was designed to detect the time course of NF-κB activation and expression of NF-κB p65 and c-Rel subunits around the contused cortex following TBI. METHODS: Adult Sprague-Dawley rats were randomly divided into sham and TBI groups at different time points. A TBI model was induced, and then the NF-κB DNA-binding activity in the surrounding areas of injured brain was detected by electrophoretic mobility shift assay. Western blotting was used to measure the protein levels of p65 and c-Rel in the nucleus. The concentrations of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) were detected by enzyme-linked immunosorbent assay. Moreover, the distribution of c-Rel and p65 was examined by immunohistochemical studies. RESULTS: There were double peaks of cerebral cortical NF-κB activity, at 3 and 10 days post-injury. Additionally, protein levels of p65 were found to be elevated and peaked at 3 days after TBI, while levels of c-Rel were elevated significantly during the later phase of injury. Furthermore, TNF-α and IL-1ß concentrations also showed a biphasic increase. CONCLUSIONS: Biphasic activation of NF-κB could be induced after experimental TBI in rats. NF-κB p65 and c-Rel subunits were elevated at different post-TBI time periods, leading to a hypothesis that different NF-κB subunits might be involved in different pathophysiological processes after TBI.

Expression of the NLRP3 inflammasome in cerebral cortex after traumatic brain injury in a rat model.

Inflammatory response plays an important role in the pathogenesis of secondary damage after traumatic brain injury (TBI). The inflammasome is a multiprotein complex involved in innate immunity and a number of studies have suggested that the inflammasome plays a critical role in a host inflammatory signaling. Nucleotide-binding domain, leucine-rich repeat, pyrin domain containing 3 (NLRP3) is a key component of the NLRP3-inflammasome, which also includes apoptotic speck-containing protein (ASC) with a cysteine protease (caspase)-activating recruitment domain and pro-caspase1. Activation of the NLRP3-inflammasome causes the processing and release of the interleukin 1 beta (IL-1ß) and interleukin 18 (IL-18). Based on this, we hypothesized that the NLRP3-inflammasome could participate in the inflammatory response following TBI. However, the expression of NLRP3-inflammasome in cerebral cortex after TBI is not well known. Rats were randomly divided into control, sham and TBI groups (including 6 h, 1 day, 3 day and 7 day sub-group). TBI model was induced, and animals were sacrificed at each time point respectively. The expression of NLRP3-inflammasome was measured by quantitative real-time polymerase chain reaction, western blot and immunohistochemistry respectively. Immunofluorescent double labeling was performed to identify the cell types of NLRP3-inflammasome's expression. Moreover, enzyme linked immunosorbent assay was used to detect the alterations of IL-1ß and IL-18 at each time point post-injury. The results showed that, TBI could induce assembly of NLRP3-inflammasome complex, increased expression of ASC, activation of caspase1, and processing of IL-1ß and IL-18. These results suggested that NLRP3-inflammasome might play an important role in the inflammation induced by TBI and could be a target for TBI therapy.

Expression of intestinal CD40 after experimental traumatic brain injury in rats.

BACKGROUND: Nuclear factor kappa B (NF-κB) has been shown to be activated in the intestine after traumatic brain injury (TBI), and results in gastrointestinal mucosal injury. In addition, CD40 has a major role in the activation of NF-κB and is up-regulated in inflammatory bowel disease. However, we found no study in the literature investigating the intestinal expression of CD40 after TBI. Hence, we designed the current study to explore the intestinal expression pattern of CD40 after TBI in rats. We hypothesized that CD40 could mediate inflammation and ultimately contribute to acute intestinal mucosal injury after TBI. METHODS: We randomly divided rats into control and TBI groups at 3, 6, 12, 24, and 72 h, respectively. We assessed the expression of CD40 by quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical study, and detected the levels of tumor necrosis factor-α (TNF-α), intracellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by enzyme-linked immunosorbent assay. RESULTS: The mRNA and protein levels of -CD40 increased by 3 and 6 h, peaked at 6 and 12 h, and remained elevated until 24 and 72 h post-injury, respectively. Levels of TNF-α, VCAM-1, and ICAM-1 also markedly increased in jejunum tissue after TBI. Interestingly, there was a positive relationship between the expression of CD40 and that of TNF-α, VCAM-1, and ICAM-1. CONCLUSIONS: CD40 could be markedly elevated in intestine after TBI in rats, and it might have an important role in the pathogenesis of acute intestinal mucosal injury mediated by inflammatory response.

Analysis of the common complications and recurrence-related factors of superior parasagittal sinus meningioma.

Objectives: Parasagittal meningioma resection is prone to postoperative complications and tumor recurrence because the tumor invades the superior sagittal sinus. This study aimed to clarify the incidence of perioperative complications and the recurrence of superior sagittal paranasal meningiomas and explored potential predictors in this context. Methods: The study retrospectively reviewed the clinical, imaging, and follow-up data of parasagittal meningiomas among patients who underwent microsurgical resection in the authors' institution from January 2008 to December 2017. Univariate and multivariate logistic regression analyses were conducted to explore independent predictors of perioperative complications and tumor recurrence. Results: A total of 212 parasagittal meningioma patients were included in this study. The incidence of perioperative complications was 23.6% (50/212), and perioperative death occurred in 6 (2.8%) patients. In univariate and multivariate logistic regression analyses of perioperative complications, peritumoral edema ≥1 cm (odds ratio [OR] 2.163, 95% confidence interval [CI] 1.057-4.428, P = 0.035) and the Sindou invasion Class V-VI(OR0.018, 95% CI 1.248-11.064, P = 0.018) were independent predictors. After an average of 83 (39-154) months of clinical follow up among the living 206 patients, 22 (10.7%) patients showed tumor recurrence. In univariate and multivariate logistic regression analyses of tumor recurrence, the Sindou invasion Class III-IV (OR 5.539, 95%CI 1.469-20.884, P = 0.011) and the Sindou invasion Class V-VI (OR 9.144, 95%CI 2.215-37.757, P = 0.002) were independent predictors. Conclusions: Peritumoral edema ≥1 cm and the Sindou invasion Class V-VI were the independent predictors of perioperative complications, and the Sindou invasion Class III-IV and the Sindou invasion Class V-VI were the independent predictors of tumor recurrence. The part of the parasagittal meningioma involving the sinus wall should be actively removed to the largest degree possible to reduce the recurrence rate.

High Expression of CISD2 in Relation to Adverse Outcome and Abnormal Immune Cell Infiltration in Glioma.

Glioma is a serious disease burden globally, with high mortality and recurrence rates. CDGSH iron sulfur domain 2 (CISD2) is an evolutionarily conserved protein that is involved in several cancers. However, its role in the prognosis and immune infiltration in glioma remains unclear. In our research, RNA-seq matrix and clinicopathological relevant data for CISD2 were downloaded from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Human Protein Atlas was used to verify the CISD2 protein level in glioma, and STRING was used to establish relative coexpression gene network. The Kaplan-Meier plotter was adopted to analyze the effect of CISD2 on prognosis. The connection between CISD2 expression and immune infiltration was analyzed using single-sample GSEA (ssGSEA), TIMER, and GEPIA. In contrast to normal tissues, CISD2 expression was significantly higher in glioma tissues, and CISD2 presented a certain diagnostic value in distinguishing glioma tissues from normal tissues. Furthermore, the CISD2 level was correlated with age, histologic grade, histological type, isocitrate dehydrogenase (IDH) status, 1p/19q codeletion status, and primary therapy outcome of glioma, while high CISD2 mRNA expression was correlated with grave overall survival. Multivariate analysis demonstrated that CISD2 was an independent risk factor for patients with glioma. Functional enrichment analysis indicated that CISD2 could regulate proliferation, immune reaction, and mitochondrial function. The results from the ssGSEA and TIMER databases confirmed that CISD2 acts a prominent role in immune cell infiltration in the tumor microenvironment, especially in low-grade glioma (LGG). Furthermore, CISD2 expression was observably correlated to M2 polarization in macrophages with glioma progression. This is the first research to investigate the immune role of CISD2 in glioma. CISD2 may be an innovative prognostic biomarker and can act as a potential target for future therapy for glioma.

Cortical network switching: possible role of the lateral septum and cholinergic arousal.

BACKGROUND: Cortical networks undergo large-scale switching between states of increased or decreased activity in normal sleep and cognition as well as in pathological conditions such as epilepsy. We previously found that focal hippocampal seizures in rats induce increased neuronal firing and cerebral blood flow in subcortical structures including the lateral septal area, along with frontal cortical slow oscillations resembling slow wave sleep. In addition, stimulation of the lateral septum in the absence of a seizure resulted in cortical deactivation with slow oscillations. HYPOTHESIS: We hypothesized that lateral septal activation might cause neocortical deactivation indirectly, possibly through impaired subcortical arousal. But how does subcortical stimulation cause slow wave activity in frontal cortex? How do arousal neurotransmitter levels (e.g. acetylcholine) change in cortex during the excitation of inhibitory projection nuclei? METHODS AND RESULTS: In the current study, we used simultaneous electrophysiology and enzyme-based amperometry in a rat model, and found a decrease in choline, along with slow wave activity in orbital frontal cortex during lateral septal stimulation in the absence of seizures. In contrast, the choline signal and local field potential in frontal cortex had no significant changes when stimulating the hippocampus, but showed increased choline and decreased slow wave activity with an arousal stimulus produced by toe pinch. CONCLUSIONS: These findings indicate that the activation of subcortical inhibitory structures (such as lateral septum) can depress subcortical cholinergic arousal. This mechanism may play an important role in large-scale transitions of cortical activity in focal seizures, as well as in normal cortical function.

Glycyrrhizic acid confers neuroprotection after subarachnoid hemorrhage via inhibition of high mobility group box-1 protein: a hypothesis for novel therapy of subarachnoid hemorrhage.

Subarachnoid hemorrhage usually results in poor clinical outcome and devastating neurological deficits. The early brain injury and delayed vasospasm after subarachnoid hemorrhage (SAH) are involved in the poor prognosis to the patients, while the mechanisms have not been well elucidated. Previous studies found an up-regulation of Toll-like receptor 4 (TLR4), inflammatory factors and high-mobility group box 1 (HMGB1) in the cortex after SAH. Increased inflammatory response contributes to the early brain injury and delayed vasospasm after SAH. Moreover, we found that the inflammatory response could be induced and amplified following recombinant HMGB1 (rHMGB1) addition in cultured neurons. Based on the latest researches in this field, we raised a hypothesis that HMGB1, a prototypical member of damage-associated molecular pattern (DAMP) family, could be passively released from the damaged neuroglia cells and hemotocyte lysis after SAH. Extracellular HMGB1 initiated the inflammation through its receptors. The inflammatory mediators then acted on the neurocytes to make them actively release HMGB1 continuously, manifesting an double phases. HMGB1 might be the key factor to induce sterile inflammation, and thus be one of the origin of early brain injury and delayed vasospasm after SAH. Inhibition of extracellular HMGB1 activities might be a novel therapeutic target for SAH to reduce the damaging inflammatory response. Glycyrrhizic acid (GA) which was extracted from liquorice and confirmed as a nature inhibitor of HMGB1 with little side-effects could inhibit extracellular HMGB1 cytokine activities and reduce the level of inflammatory response, thus alleviating early brain injury and cerebrovasospasm. GA might be a new novel therapy of SAH for better outcomes.

Expression and cell distribution of myeloid differentiation primary response protein 88 in the cerebral cortex following experimental subarachnoid hemorrhage in rats: a pilot study.

Subarachnoid hemorrhage (SAH) which is mostly caused by aneurysm rupture causes a lot of death every year. Convincing evidence can be made that inflammation contributes to the poor outcome caused by SAH. Toll like receptors (TLRs), nuclear factor-kappaB (NF-κB), Interleukin 1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) are involved in the damaging inflammation process after SAH. Myeloid differentiation primary response protein 88 (MyD88) is essential to deliver TLRs signals down to NF-κB and pro-inflammatory factors. The study aims to detect the expression level of MyD88 and know more about the role of MyD88 after SAH. Sprague Dawley (SD) rats were randomly divided into sham group and SAH groups at 2h, 6h, 12h and on day 1, day 2, day 3, day 5 and day 7. SAH groups suffered experimental subarachnoid hemorrhage by injection of 0.3 ml autoblood into the prechiasmatic cistern. MyD88 expression is measured by western blot analysis, real-time polymerase chain reaction (PCR), immunohistochemistry and immunofluorescence. The levels of TNF-α and IL-1ß were measured by real-time PCR. Our results demonstrated MyD88 expression was increased after SAH, and peaked on day 1 and day 5, which showed a parallel time course to the up-regulation of IL-1ß, there was a highly positive relationship between them. Immunohistochemistry and immunofluorescence results indicated up-regulated MyD88 was mainly located in neurons while over expressed MyD88 could also be found in astrocytes and microglia. These results might have important implications during the administration of specific MyD88 antagonists in order to prevent or reduce inflammatory response following SAH.