Chongjie Cheng

Bexarotene protects against traumatic brain injury in mice partially through apolipoprotein E.

Bexarotene has been proved to have neuroprotective effects in many animal models of neurological diseases. However, its neuroprotection in traumatic brain injury (TBI) is still unknown. This study aims to explore the neuroprotective effects of bexarotene on TBI and its possible mechanism. Controlled cortical impact (CCI) model was used to simulate TBI in C57BL/6 mice as well as APOE gene knockout (APOE-KO) mice. After CCI, mice were daily dosed with bexarotene or vehicle solution intraperitoneally. The motor function, learning and memory, inflammatory factors, microglia amount, apoptosis condition around injury site and main side-effects were all measured. The results showed that, after CCI, bexarotene treatment markedly improved the motor function and spatial memory in C57BL/6 compare to APOE-KO mice which showed no improvement. The inflammatory cytokines, microglia amount, cell apoptosis rate, and protein of cleaved caspase-3 around the injury site were markedly upregulated after TBI in both C57BL/6 and APOE-KO mice, and all these upregulation were significantly mitigated by bexarotene treatment in C57BL/6 mice, but not in APOE-KO mice. No side-effects were detected after consecutive administration. Taken together, bexarotene inhibits the inflammatory response as well as cell apoptosis and improves the neurological function of mice after TBI partially through apolipoprotein E. This may make it a promising candidate for the therapeutic treatment after TBI.

Peroxisome Proliferator–Activated Receptor β/δ Alleviates Early Brain Injury After Subarachnoid Hemorrhage in Rats

Background and Purpose— Early brain injury is proposed to be the primary cause of the poor outcome after subarachnoid hemorrhage (SAH), which is closely related to the neural apoptosis. To date, the relationship between peroxisome proliferator–activated receptor &bgr;/&dgr; (PPAR&bgr;/&dgr;) and nuclear factor-&kgr;B/matrix metalloproteinase-9 (NF-&kgr;B/MMP-9) pathway, both of which are closely related to apoptotic effects, has been poorly studied in SAH. The present study was undertaken to evaluate the effects of PPAR&bgr;/&dgr; on early brain injury and NF-&kgr;B/MMP-9 pathway after SAH in rats. Methods— SAH model was established by injecting nonheparinized autologous arterial blood into the prechiasmatic cistern in male Sprague–Dawley rats. Adenoviruses or small interfering RNAs were injected into the right lateral cerebral ventricle to, respectively, up- or downregulate PPAR&bgr;/&dgr; expression before SAH. All animals were assessed with a neurological score and then killed at 24 hours after SAH surgery. The indexes of brain water content, blood–brain barrier permeability, and apoptosis were used to detect brain injury. The expression of PPAR&bgr;/&dgr;, NF-&kgr;B, and MMP-9 were measured by immunohistochemistry, gelatin zymography, and Western Blot methods, respectively. In addition, GW0742, a specific agonist of PPAR&bgr;/&dgr;, was used to treat SAH in rats, the effects of which were evaluated by neurological scoring and Evans blue extravasation. Results— Overexpression of PPAR&bgr;/&dgr; by adenoviruses treatment significantly ameliorated brain injury with improvement in neurological deficits, brain edema, blood–brain barrier impairment, and neural cell apoptosis at 24 hours after SAH in rats, whereas downregulation of PPAR&bgr;/&dgr; by small interfering RNAs administration resulted in the reverse effects of the above. The expression levels of NF-&kgr;B and MMP-9 were markedly downregulated when PPAR&bgr;/&dgr; increased after PPAR&bgr;/&dgr; adenovirus transfection and upregulated when PPAR&bgr;/&dgr; decreased by PPAR&bgr;/&dgr; small interfering RNAs treatment. Moreover, GW0742 improved neurological deficits and reduced Evans blue extravasation at 24 hours after SAH. Conclusions— PPAR&bgr;/&dgr;’s overexpression may attenuate early brain injury after rats’ SAH administration, which reduces neural apoptosis possibly through blocking NF-&kgr;B/MMP-9 pathway.

Altered expression of long non-coding RNA and mRNA in mouse cortex after traumatic brain injury

BACKGROUND AND OBJECTIVE The present study aims to detect the altered lncRNA expression in the mouse cortex after traumatic brain injury (TBI). We also simultaneously detected the altered mRNA profile to further analyze the possible function of lncRNA. METHOD C57BL/6 mice (n=18) were used to construct a controlled cortical impact model. At 24h post-TBI, the cortex around injury site was collected and the total RNA was extracted to construct the cDNA library. RNA sequencing (RNA-seq) was carried out followed by RT-PCR for confirmation. Bioinformatic analysis (including GO analysis, KEGG pathway and co-expression analysis) also were performed. RESULTS A total of 64,530 transcripts were detected in the current sequencing study, in which 27,457 transcripts were identified as mRNA and 37,073 transcripts as lncRNA. A total of 1580 mRNAs (1430 up-regulated and 150 down-regulated) and 823 lncRNAs (667 up-regulated and 156 down-regulated) were significantly changed according to the criteria ( (|)log2((fold change))|>1 and P<0.05). These altered mRNAs were mainly related to inflammatory and immunological activity, metabolism, neuronal and vascular network. The expression of single lncRNA may be related with several mRNAs, and so was the mRNA. Also, a total of 360 new mRNAs and 8041 new lncRNAs were identified. The good reproducibility and reliability of RNA-seq were confirmed by RT-PCR. CONCLUSION Numerous lncRNAs and mRNAs were significantly altered in mouse cortex around the injury site 24h after TBI. Our present data may provide a promising approach for further study about TBI.

Effects of ApoE on intracellular calcium levels and apoptosis of neurons after mechanical injury.

OBJECTIVE The current study aimed to explore the effects of apolipoprotein e (ApoE) on intracellular calcium ([Ca(2+)]i) and apoptosis of neurons after mechanical injury in vitro. METHODS A neuron mechanical injury model was established after primary neurons obtained from APOE knockout and wild-type (WT) mice, and four experimental groups were generated: Group-ApoE4, Group-ApoE3, Group-ApoE(-) and Group-WT. Recombinant ApoE4 and ApoE3 were added to Group-ApoE4 and Group-ApoE3 respectively, and Group-ApoE(-) and Group-WT were control groups. Intracellular calcium was labeled by fluo-3/AM and examined using laser scanning confocal microscope and flow cytometry, and the apoptosis of neurons was also evaluated. RESULTS The intracellular calcium levels and apoptosis rates of mice neurons were significantly higher in Group-ApoE4 than in Group-ApoE3 and Group-WT after mechanical injury. However, without mechanical injury on neurons, no significant differences in intracellular calcium levels and apoptosis rates were found among all four experimental groups. The effects of ApoE4 on intracellular calcium levels and apoptosis rates of injured neurons were partly decreased by EGTA treatment. CONCLUSION Compared with ApoE3-treatment and WT neurons, ApoE4 caused higher intracellular calcium levels and apoptosis rates of neurons after mechanical injury. This suggested APOE polymorphisms may affect neuron apoptosis after mechanical injury through different influences on intracellular calcium levels.

Intraventricular apolipoprotein ApoJ infusion acts protectively in Traumatic Brain Injury

Traumatic brain injury (TBI) is the leading cause of mortality and morbidity in youth, but to date, effective therapies are still lacking. Previous studies revealed a marked response of apolipoprotein J (ApoJ) expression to the brain injury. The aim of this study was to determine the potential roles of ApoJ in functional recovery following TBI. After controlled cortex impact (CCI), a TBI model, in adult wild‐type mice, ApoJ expression was up‐regulated since 6 h post‐injury and sustained for 5 days. Animals infused with recombinant human ApoJ intraventricularly at 30 min prior to CCI showed significantly reduced oxidative stress (3‐nitrotyrosine, 4‐hydroxynonenal) and complement activation (C5b‐9). In addition, ApoJ treatment was shown to suppress the inflammatory response (glial activation, cytokine expression), blood–brain barrier disruption (Evans blue extravasation), and cerebral edema (water content) induced by CCI. Concomitantly, improved neuronal maintenance and neurological behavioral performance were observed in ApoJ‐treated mice compared with the vehicle group. These findings support a neuroprotective role of ApoJ via multifunctional pathways, providing a novel and encouraging treatment strategy for TBI.

A poE Influences the Blood-Brain Barrier Through the NF-κB/MMP-9 Pathway After Traumatic Brain Injury

Apolipoprotein E (ApoE), encoded by the ApoE gene (APOE), influences the outcomes of traumatic brain injury (TBI), but the mechanism remains unclear. The present study aimed to investigate the effects of different ApoEs on the outcome of TBI and to explore the possible mechanisms. Controlled cortical impact (CCI) was performed on APOEε3 (E3) and APOEε4 (E4) transgenic mice, APOE-KO (KO) mice, and wild type (WT) mice to construct an in vivo TBI model. Neurological deficits, blood brain barrier (BBB) permeability and brain edema were detected at days 1, 3, and 7 after TBI. The results revealed no significant differences among the four groups at day 1 or day 3 after injury, but more severe deficits were found in E4 and KO mice than in E3 and WT mice. Furthermore, a significant loss of tight junction proteins was observed in E4 and KO mice compared with E3 and WT mice at day 7. Additionally, more expression and activation of NF-κB and MMP-9 were found in E4 mice compared with E3 mice. Different ApoEs had distinct effects on neuro-function and BBB integrity after TBI. ApoE3, but not E4, might inhibit the NF-κB/MMP-9 pathway to alleviate BBB disruption and improve TBI outcomes.

PPARβ/δ, a Novel Regulator for Vascular Smooth Muscle Cells Phenotypic Modulation and Vascular Remodeling after Subarachnoid Hemorrhage in Rats

Cerebral vascular smooth muscle cell (VSMC) phenotypic switch is involved in the pathophysiology of vascular injury after aneurysmal subarachnoid hemorrhage (aSAH), whereas the molecular mechanism underlying it remains largely speculative. Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) has been implicated to modulate the vascular cells proliferation and vascular homeostasis. In the present study, we investigated the potential role of PPARβ/δ in VSMC phenotypic switch following SAH. Activation of PPARβ/δ by GW0742 and adenoviruses PPARβ/δ (Ad-PPARβ/δ) significantly inhibited hemoglobin-induced VSMC phenotypic switch. However, the effects of PPARβ/δ on VSMC phenotypic switch were partly obstacled in the presence of LY294002, a potent inhibitor of Phosphatidyl-Inositol-3 Kinase-AKT (PI3K/AKT). Furthermore, following study demonstrated that PPARβ/δ-induced PI3K/AKT activation can also contribute to Serum Response Factor (SRF) nucleus localization and Myocardin expression, which was highly associated with VSMC phenotypic switch. Finally, we found that Ad-PPARβ/δ positively modulated vascular remodeling in SAH rats, i.e. the diameter of basilar artery and the thickness of vessel wall. In addition, overexpression of PPARβ/δ by adenoviruses significantly improved neurological outcome. Taken together, this study identified PPARβ/δ as a useful regulator for VSMC phenotypic switch and vascular remodeling following SAH, providing novel insights into the therapeutic strategies of delayed cerebral ischemia.

The Clinical Value of d-Dimer Level in Patients with Nonaneurysmal Subarachnoid Hemorrhage

OBJECTIVE More nonaneurysmal subarachnoid hemorrhage (NaSAH) are found in clinical practice. However, the precise mechanisms in which d-dimer level is associated with clinical condition in patients with NaSAH remain unclear. But even more, the data assessing the risk of clinical course in the patients with NaSAH are scarce. Our objective was to investigate whether d-dimer levels correlated with complication and outcome in patients with NaSAH. METHODS Between February 2013 and May 2017, 92 patients suffering from NaSAH were treated in our hospital. Patient characteristics, radiologic features, laboratory findings, complications, and outcomes were analyzed retrospectively. Patients were stratified into the perimesencephalic (PM) subarachnoid hemorrhage (SAH) group and the nonperimesencephalic (NPM) SAH group according to the bleeding type, and the NPM-SAH group was further divided into 2 subgroups into the NPM-elevated group and the NPM-normal group based on the value of the d-dimer. After statistical analysis, the NPM-SAH and PM-SAH groups were compared; the same was true for the NPM-elevated group and the NPM-normal group. RESULTS The rate of complications in the NPM-SAH group was higher than in the PM-SAH group, including early hydrocephalus, delayed cerebral ischemia, clinical vasospasm, pneumonia, and hyponatremia. Our results showed that d-dimer levels in patients with NPM-SAH were more elevated than in those with PM-SAH. Further analysis of subgroups demonstrated that patients with elevated d-dimer levels had a higher incidence of complications than those with normal d-dimer levels, especially the risks of shunt-dependent hydrocephalus and pneumonia. In addition, disability, and even death, could be seen in patients with higher levels of d-dimer, but the long-term outcomes were not particularly obvious between these groups. CONCLUSIONS Elevated d-dimer levels on admission were significantly associated with complication in patients with NPM-SAH. In addition to conventional radiologic diagnosis, d-dimer levels can increase the ability of a rapid differential diagnosis between NPM-SAH and PM-SAH.

Bexarotene protects against neurotoxicity partially through a PPARγ-dependent mechanism in mice following traumatic brain injury

Traumatic brain injury (TBI) causes a high rate of mortality and disability worldwide, and there exists almost none effective drugs to protect against TBI. Neurotoxicity occurring after TBI can be derived from microglia and astrocytes, and causes neuronal death and synapse loss. Bexarotene has been demonstrated to protect neurons in CNS diseases. In the present study, we aimed to investigate the potential role of bexarotene in protecting against neurotoxicity after TBI, as well as the underlying mechanism. The controlled cortical impact (CCI) model was established on adult C57BL/6 mice, followed by intraperitoneal administration of bexarotene for 14 consecutive days. We found that bexarotene improved sensorimotor function and cognitive recovery in CCI mice. In addition, bexarotene decreased neuronal death and synapse loss, as well as inhibited apoptotic cascade. Moreover, bexarotene treatment reduced M1 microglia polarization, microglia-derived pro-inflammatory cytokines, and the number of A1 astrocytes after CCI. These effects of bexarotene were partially abolished by T0070907, an antagonist of peroxisome proliferator-activated receptor gamma (PPARγ). Additionally, bexarotene enhanced nuclear translocation and transcriptional activity of PPARγ. These findings show that bexarotene inhibits neurotoxicity in mice after TBI, at least in part through a PPARγ-dependent mechanism.

Clinical and Basic Evaluation of the Prognostic Value of Uric Acid in Traumatic Brain Injury

Background: As a major antioxidant in serum, uric acid (UA) was once considered only as the leading cause of gout; however, recent studies have validated its neuroprotective role in ischemic stroke. Because the potential protective effects of UA in traumatic brain injury (TBI) remain largely unknown, this study investigated the role of UA in TBI in both clinical patients and experimental animals. Methods: In TBI patients, serum UA concentrations were measured within 3 days after injury. Clinical outcomes at discharge were classified according to the Glasgow Outcome Scale: good outcome (4-5) and poor outcome (1-3). Risk factors for good outcome were identified via backward logistic regression analysis. For the animal study, a controlled cortical impact (CCI) injury model was established in mice. These mice were given UA at different doses intraperitoneally, and subsequent UA concentrations in mouse serum and brain tissue were determined. Neurological function, oxidative stress, inflammatory response, neuronal maintenance, cerebral blood flow, and lesion size were also assessed. Results: The serum UA level was significantly lower in TBI patients who had a good outcome (P<0.01), and low serum UA was an independent predictor of good outcome after TBI (P<0.01; odds ratio, 0.023; 95% confidence interval, 0.006-0.082). Consistently, decreased levels of serum UA were observed in both TBI patients and CCI animals (P<0.05), whereas the UA concentration was increased in CCI brain tissue (P<0.05). Administration of UA further increased the UA level in brain tissue as compared to that in control animals (P<0.05). Among the different doses administered, 16 mg/kg UA improved sensorimotor functional recovery, spatial learning, and memory in CCI mice (P<0.05). Moreover, oxidative stress and the inflammatory response were inhibited by UA treatment (P<0.05). UA treatment also improved neuronal maintenance and cortical blood flow (P<0.05) but not lesion size (P>0.05). Conclusions: UA acted to attenuate neuronal loss, cerebral perfusion impairment and neurological deficits in TBI mice through suppression of neuronal and vascular oxidative stress. Following TBI, active antioxidant defense in the brain may result in consumption of UA in the serum, and thus, a decreased serum UA level could be predictive of good clinical recovery.