BackgroundEarly brain injury (EBI) is considered a major contributor to the high morbidity and mortality associated with subarachnoid haemorrhage (SAH). Both of sterile inflammation and apoptosis are considered the important causes of EBI. Recently, it was confirmed that thioredoxin-interacting protein (TXNIP) not only participates in inflammatory amplification but also stimulates the apoptosis signalling cascade pathway. However, whether the effects of TXNIP influence the pathogenesis of SAH remains unclear. Here, we hypothesize that TXNIP activity induced by endoplasmic reticulum stress (ER stress) may contribute to the pathogenesis of EBI through pro-inflammatory and pro-apoptotic mechanisms.MethodsA total of 299 male Sprague–Dawley rats were used to create SAH models. Resveratrol (RES, 60 mg/kg) and two TXNIP small interfering RNA (siRNA) were used to inhibit TXNIP expression. The specific inhibitors of ER stress sensors were used to disrupt the link between TXNIP and ER stress. SAH grade, neurological deficits, brain water content and blood–brain barrier (BBB) permeability were evaluated simultaneously as prognostic indicators. Fluorescent double-labelling was employed to detect the location of TXNIP in cerebral cells. Western blot and TUNEL were performed to study the mechanisms of TXNIP and EBI.ResultsWe found that TXNIP expression significantly increased after SAH, peaking at 48 h (0.48 ± 0.04, up to 3.2-fold) and decreasing at 72 h after surgery. This process was accompanied by the generation of inflammation-associated factors. TXNIP was expressed in the cytoplasm of neurons and was widely co-localized with TUNEL-positive cells in both the hippocampus and the cortex of SAH rats. We discovered for the first time that TXNIP was co-localized in neural immunocytes (microglia and astrocytes). After administration of RES, TXNIP siRNA and ER stress inhibitors, TXNIP expression was significantly reduced and the crosstalk between TXNIP and ER stress was disrupted; this was accompanied by a reduction in inflammatory and apoptotic factors, as well as attenuation of the prognostic indices.ConclusionsThese results may represent the critical evidence to support the pro-inflammatory and pro-apoptotic effects of TXNIP after SAH. Our data suggest that TXNIP participates in EBI after SAH by mediating inflammation and apoptosis; these pathways may represent a potential therapeutic strategy for SAH treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-017-0878-6) contains supplementary material, which is available to authorized users.

Iron metabolism disturbances play an important role in early brain injury (EBI) after subarachnoid hemorrhage (SAH), and hepcidin largely influences iron metabolism. Importantly, iron metabolism may be associated with ferroptosis, recently a nonapoptotic iron-dependent form of cell death that may have a great impact on brain injury after SAH. We investigated hepcidin on iron metabolism and ferroptosis involving divalent metal transporter 1 (DMT1), and ferroportin-1 (FPN1) in a rat model of SAH. Male Sprague-Dawley rats were subjected to the endovascular perforation to induce SAH, and treated with heparin (inhibitor of hepcidin), or oncostatin M (OSM, inducer of hepcidin), or ebselen (inhibitor of DMT1) by intracerebroventricular injections. Hepcidin, DMT1, FPN1 and glutathione peroxidase 4 (GPX4), were detected by western blot and immunofluorescence. Iron metabolism was detected through Perl’s iron staining and iron content assay. Ferroptosis, the ROS production, lipid peroxidation (LPO) was evaluated by monitoring methane dicarboxylic aldehyde (MDA), glutathione (GSH), glutathione peroxidase 4 (GPX4) activity, and transmission electron microscopy. Neurological deficit scores, Evans blue staining and brain water content were also determined to detect EBI 72 h after SAH. Our results showed that inhibition of DMT1 by ebselen could suppress iron accumulation and lipid peroxidation, and thereby alleviate ferroptosis and EBI in SAH rats. Heparin downregulated the expression of hepcidin and DMT1, increased FPN1, and exerted protective effects that were equivalent to those of ebselen on ferroptosis and EBI. In addition, OSM increased the expression of hepcidin and DMT1, decreased FPN1, and aggravated ferroptosis and EBI, while the effect on ferroptosis was reversed by ebselen. Therefore, the study revealed that hepcidin could regulate iron metabolism and contribute to ferroptosis via DMT1 signaling activation in rats with EBI after SAH.

Early brain injury (EBI) is considered to be the major factor associated with high morbidity and mortality after subarachnoid haemorrhage (SAH). Apoptosis is the major pathological mechanism of EBI, and its pathogenesis has not been fully clarified. Here, we report that thioredoxin-interacting protein (TXNIP), which is induced by protein kinase RNA-like endoplasmic reticulum (ER) kinase (PERK), participates in EBI by promoting apoptosis. By using adult male Sprague-Dawley rats to establish SAH models, as well as Terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining, immunofluorescence, and western blot, we found that TXNIP expression significantly increased after SAH in comparison to the sham group and peaked at 48 h (up to 3.2-fold). Meanwhile, TXNIP was widely expressed in neurons and colocalized with TUNEL-positive cells in the hippocampus and cortex of SAH rats. After administration of TXNIP inhibitor-resveratrol (60 mg/kg), TXNIP small interfering RNA (siRNA) and the PERK inhibitor GSK2656157, TXNIP expression was significantly reduced, accompanied by an attenuation of apoptosis and prognostic indicators, including SAH grade, neurological deficits, brain water content, and blood-brain barrier (BBB) permeability. Collectively, these results suggest that TXNIP may participate in EBI after SAH by mediating apoptosis. The blockage of TXNIP induced by PERK could be a potential therapeutic strategy for SAH treatment.

Early brain injury (EBI) was reported to be the primary cause of high mortality and poor outcomes in subarachnoid hemorrhage (SAH) patients, and apoptosis is regarded as the most important physiopathologic mechanism during EBI. Recently, our team found that thioredoxin-interacting protein (TXNIP) links endoplasmic reticulum stress (ER stress) to neuronal apoptosis and aggravates EBI. However, the other underlying mechanisms remain unknown. Mitochondria are considered to be the central points in integrating apoptotic cell death. However, whether crosstalk between TXNIP and the mitochondria-mediated intrinsic apoptotic pathway is effective on EBI has not been previously reported. Therefore, we created an endovascular perforation SAH model in Sprague-Dawley rats to determine the possible mechanism. We found that TXNIP expression in apoptotic neurons significantly increased in the SAH group compared with the sham group. In addition, increased TXNIP expression was accompanied by remarkable changes in mitochondrial-related antiapoptotic and proapoptotic factors. Furthermore, resveratrol (RES, a TXNIP inhibitor) administration significantly downregulated the expression of TXNIP and mitochondria-related proapoptotic factors. Additionally, it attenuated SAH prognostic indicators, such as brain edema, blood-brain barrier permeability, and neurological deficits. Therefore, our study further confirms that TXNIP may participate in neuronal apoptosis through the mitochondrial signaling pathway and that TXNIP may be a target for SAH treatment.

Background: Several studies, including a randomized clinical trial, have demonstrated that atorvastatin may be an effective nonoperative treatment for chronic subdural hematoma (CSDH). Atorvastatin is mainly used to regulate lipid metabolism. However, few studies investigated the association between serum lipids level and risk of CSDH.Methods: We conducted a retrospective case-control study to assess the relationship between fasting lipids (total cholesterol, triglyceride, HDL-C and LDL-C), apolipoproteins (ApoA1, ApoB) and risk of CSDH. Using a one-to-three case–control ratio, 137 CSDH patients were included in our study. Conditional logistic regression was used to examine the relationship between lipids and apolipoproteins biomarkers and risk of CSDH.Result: In univariate analysis, baseline levels of total cholesterol (P<0.001), HDL-C (P<0.001) and ApoA1 were significantly lower among patients with CSDH, while levels of ApoB were higher. No significant difference for triglyceride (P=0.15) and LDL-C (P=0.47) were observed. In multivariable analysis, total cholesterol (OR for the highest vs lowest quartile 0.34, 05%CI 0.19-0.64, P<0,001), triglycerides (OR 1.98, 95%CI 1.05-3.71, p<0,05), HDL-C (OR 0.26, 95%CI 0.13-0.52, P<0,001), ApoA1 (OR 0.27, 95%CI 0.14-0.52, P<0,001) were significantly associated with CSDH, when conditioned on age and gender, and adjusted for head trauma and hypertension. Additional adjustment for all covariates of interest don’t substantially change the multivariable associations.Conclusion: Among a panel of lipids and apolipoproteins biomarkers, total cholesterol, triglycerides, HDL-C, ApoA1 were significantly associated with CSDH.