Time dependent neuroprotection of dexamethasone in experimental focal cerebral ischemia: The involvement of NF-κB pathways

Delayed encephalopathy after acute carbon monoxide poisoning: a case study

Delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) is a relatively rare inflammatory-associated neurometabolic complication. In this article, we present a case report of a 50-year-old male patient with a history of carbon monoxide poisoning. This acute poisoning, although successfully controlled during a stay in the intensive care unit of a local hospital, later led to persistent neurological symptoms. The patient was then treated in the inpatient unit of the rehabilitation clinic, where cognitive deterioration began to develop 20 days after admission. Subsequent examination using EEG and magnetic resonance imaging confirmed severe encephalopathy later complicated by SARS-CoV-2 infection with fatal consequences due to bronchopneumonia. Because currently there are no approved guidelines for the management of DEACMP, we briefly discuss the existing challenges for future studies, especially the application of rational immunosuppressive therapy already in the acute treatment phase of CO poisoning, which could prevent the development of a severe form of DEACMP.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Dexamethasone-Loaded Hydrogels Improve Motor and Cognitive Functions in a Rat Mild Traumatic Brain Injury Model

Functional recovery following traumatic brain injury (TBI) is limited due to progressive neuronal damage resulting from secondary injury-associated neuroinflammation. Steroidal anti-inflammatory drugs, such as dexamethasone (DX), can reduce neuroinflammation by activated microglia and infiltrated macrophages. In our previous work, we developed hydrolytically degradable poly(ethylene) glycol-bis-(acryloyloxy acetate) (PEG-bis-AA) hydrogels with dexamethasone (DX)-conjugated hyaluronic acid (HA-DXM) and demonstrated that dexamethasone-loaded hydrogels (PEG-bis-AA/HA-DXM) can reduce neuroinflammation, apoptosis, and lesion volume and improve neuronal cell survival and motor function recovery at seven days post-injury (DPI) in a rat mild-TBI model. In this study, we investigate the effects of the local application of PEG-bis-AA/HA-DXM hydrogels on motor function recovery at 7 DPI and cognitive functional recovery as well as secondary injury at 14 DPI in a rat mild-CCI TBI model. We observed that PEG-bis-AA/HA-DXM-treated animals exhibit significantly improved motor functions by the rotarod test and cognitive functions by the Morris water maze test compared to untreated TBI animals. We also observed that PEG-bis-AA/HA-DXM hydrogels reduce the inflammatory response, apoptosis, and lesion volume compared to untreated animals at 14 DPI. Therefore, PEG-bis-AA/HA-DXM hydrogels can be promising a therapeutic intervention for TBI treatment.

Isosteviol Sodium (STVNA) Reduces Pro-Inflammatory Cytokine IL-6 and GM-CSF in an In Vitro Murine Stroke Model of the Blood–Brain Barrier (BBB)

Early treatment with glucocorticoids could help reduce both cytotoxic and vasogenic edema, leading to improved clinical outcome after stroke. In our previous study, isosteviol sodium (STVNA) demonstrated neuroprotective effects in an in vitro stroke model, which utilizes oxygen-glucose deprivation (OGD). Herein, we tested the hypothesis that STVNA can activate glucocorticoid receptor (GR) transcriptional activity in brain microvascular endothelial cells (BMECs) as previously published for T cells. STVNA exhibited no effects on transcriptional activation of the glucocorticoid receptor, contrary to previous reports in Jurkat cells. However, similar to dexamethasone, STVNA inhibited inflammatory marker IL-6 as well as granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion. Based on these results, STVNA proves to be beneficial as a possible prevention and treatment modality for brain ischemia-reperfusion injury-induced blood–brain barrier (BBB) dysfunction.

Dexamethasone Protects Against Ischaemic Brain Injury via Inhibiting the pAkt Signalling Pathway Through Increasing Hap1

Dexamethasone has been reported to reduce the infarct volume and protect neurological function after ischaemic injury, but the mechanism of Dex in brain injury is not clear. We aimed to study the mechanism by which dexamethasone protects against ischaemic brain injury. Western blotting was to detected the expression of Hap1,TrkB, Akt and Erk; TTC staining to analyse ischemic volume; neurological deficit evaluation to test degree of ischemic injury; immunofluorescence staining to analyse the distribution of Hap1; and the MCAO model was used to study these processes. All data are expressed as the means ± SEM and were analysed by GraphPad Prism 6. P < 0.05 was considered statistically significant. After dexamethasone (Dex) treatment, Hap1 levels were increased and peaked at 2 days; then, we found that body weight was decreased in Hap1-/+ mice. Further study showed that Dex treatment reduced the ischaemic volume and improved neurological function. Finally, we showed that Hap1 regulated the levels of pTrkB, pAkt and pErk 1/2 in ischaemic injury after Dex treatment. Our data suggest that dexamethasone protects against ischaemic brain injury by inhibiting the pAkt signalling pathway through increasing Hap1.

Donepezil protects glycerol-induced acute renal failure through the cholinergic anti-inflammatory and nitric oxide pathway in rats

OBJECTIVES

Inflammation as well as oxygen metabolite play important roles in renal injury during pathogenesis of rhabdomyolysis induced myoglobinuric acute renal failure (ARF). The aim of this study was to investigate the protective effects of donepezil on immune responses in rats with glycerol-induced ARF.

METHODS

Sixty male rats were randomly divided into six groups, the rats were given normal saline (10 ml/kg, i.m.), glycerol (50%, 10 ml/kg, i.m.), glycerol plus dexamethasone (0.1 mg/kg, i.g.), and glycerol plus donepezil (1, 5 and 10 mg/kg, i.g.) respectively. After two weeks of glycerol injections, the kidney tissues and blood samples were harvested for future biochemical and pathology analysis. The levels of creatinine (Cr) and urea nitrogen (BUN) in plasma, the content of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) activity, total nitric oxide synthase (TNOS), inducible nitric oxide synthase (iNOS), endothelial NO synthase (eNOS) were evaluated in renal tissues. In addition, interleukin-6 (IL-6), tumor necrosis factors-α (TNF-α) in renal tissues were also determined.

RESULTS

Donepezil treatment protected rats from renal dysfunction in a dose-dependent manner and through the cholinergic anti-inflammatory pathway. Additionally, donepezil significantly reduced tubular damages, prevented neutrophil infiltration and decreased productions of the IL-6, TNF-α, nitric oxide content and oxidative damage.

CONCLUSIONS

These data indicate that donepezil exerts a protective anti-inflammatory effect during ARF through the cholinergic pathway and Nitric oxide pathway. In addition, this study could provide an opportunity to overcome the effect of surgical cholinergic denervation during kidney transplantation and other injury.

Electroacupuncture Attenuates Inflammation after Ischemic Stroke by Inhibiting NF-κB-Mediated Activation of Microglia

Microglial activation and microglia-mediated inflammation play an important role in the occurrence, development, and outcome of stroke. Brain injury induces the activation and release of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin- (IL-) 1β, and IL-6. Many studies have confirmed that acupuncture is effective in treating ischemic stroke. However, its protective mechanism against ischemic brain injury is complex and multifactorial. In this study, we observed the effects of electroacupuncture at Baihui (GV20) and Dazhui (GV14) on microglial activation and inflammation in the cortical ischemic penumbra (IP) of permanent middle cerebral artery occlusion (pMCAO) rats. It was found that electroacupuncture inhibited the degeneration and necrosis of microglia in the cortical IP and ameliorated mitochondrial damage. Immunofluorescence and western blot analysis showed that microglia were in a resting state or weakly activated in the normal brain. After cerebral ischemia, the expression of microglial markers (Iba-1 and CD11b) increased, and NF-κB p65, IL-1β, and TNF-α expression gradually increased. The dynamic changes were generally temporally consistent. Electroacupuncture downregulated the expressions of Iba-1 and CD11b. Additionally, it inhibited the expression of NF-κB p65, IL-1β, and TNF-α and reduced the conversion of microglia to the M1 phenotype after ischemia. Electroacupuncture regulated the activation of microglia and microglia-mediated inflammation after cerebral ischemia, confirming the relevant theories regarding the effect of acupuncture treatment on cerebral ischemia and guiding clinical practice.

Phyllanthus amarus prevents LPS-mediated BV2 microglial activation via MyD88 and NF-κB signaling pathways

BACKGROUND

Phyllanthus amarus has been shown to attenuate lipopolysaccharide (LPS)-induced peripheral inflammation but similar studies in the central nervous system are scarce. The aim of the present study was to investigate the neuroprotective effects of 80% ethanol extract of P. amarus (EPA) in LPS-activated BV2 microglial cells.

METHODS

BV2 microglial cells c for 24 h, pre-treated with EPA for 24 h prior to LPS induction for another 24 h. Surface expression of CD11b and CD40 on BV2 cells was analyzed by flow cytometry. ELISA was employed to measure the production of pro-inflammatory mediators i.e. nitric oxide (NO) and tumor necrosis factor (TNF)-α. Western blotting technique was used to determine the expression of inducible nitric oxide synthase (iNOS), myeloid differentiation protein 88 (MYD88), nuclear factor kappa B (NF-κB), caspase-1, and mitogen activated protein kinase (MAPK).

RESULTS

Qualitative and quantitative analyses of the EPA using a validated ultra-high pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method indicated the presence of phyllanthin, hypophyllanthin, niranthin, ellagic acid, corilagin, gallic acid, phyltetralin, isolintetralin and geraniin. EPA suppressed the production of NO and TNFα in LPS-activated BV2 microglial cells. Moreover, EPA attenuated the expression of MyD88, NF-κB and MAPK (p-P38, p-JNK and p-ERK1/2). It also inhibited the expression of CD11b and CD40. EPA protected against LPS-induced microglial activation via MyD88 and NF-κB signaling in BV2 microglial cells.

CONCLUSIONS

EPA demonstrated neuroprotective effects against LPS-induced microglial cells activation through the inhibition of TNFα secretion, iNOS protein expression and subsequent NO production, inhibition of NF-κB and MAPKs mediated by adapter protein MyD88 and inhibition of microglial activation markers CD11b and CD40.

Ischemia/Reperfusion Injury: Pathophysiology, Current Clinical Management, and Potential Preventive Approaches

Myocardial ischemia reperfusion syndrome is a complex entity where many inflammatory mediators play different roles, both to enhance myocardial infarction-derived damage and to heal injury. In such a setting, the establishment of an effective therapy to treat this condition has been elusive, perhaps because the experimental treatments have been conceived to block just one of the many pathogenic pathways of the disease, or because they thwart the tissue-repairing phase of the syndrome. Either way, we think that a discussion about the pathophysiology of the disease and the mechanisms of action of some drugs may shed some clarity on the topic.