Parthenolide is neuroprotective in rat experimental stroke model: downregulating NF-κB, phospho-p38MAPK, and caspase-1 and ameliorating BBB permeability

Parthenolide induces gallbladder cancer cell apoptosis via MAPK signalling

Objective

Parthenolide (PTL) has a wide range of clinical applications owing to its anti-inflammatory and antitumor effects. To date, the antitumor effect of PTL on gallbladder cancer (GBC) remains largely unknown. Therefore, we aimed to investigate the biological effects of PTL on GBC.

Methods

The cellular viability and proliferation of GBC-SD and NOZ cell lines after treatment with different concentrations of PTL were analyzed using the Cell Counting Kit-8 (CCK8)assay and colony formation assay. Apoptosis analysis was performed using flow cytometry. Hoechst staining was performed. RNA sequencing (RNA-seq) was performed to identify PTL-related genes and signalling pathways. Furthermore, we confirmed the involvement of these signalling pathways by qRT-PCR and western blotting. For the in-vivo experiments, a xenograft model was used to evaluate the effects of PTL on the proliferation of NOZ cells.

Results

PTL significantly inhibited GBC cell growth in vitro and induced apoptosis in the GBC-SD and NOZ cell lines in a dose-dependent manner. RNA sequencing data showed that the immune response and mitogen-activated protein kinase (MAPK) signalling pathways are closely associated with PTL-induced gallbladder cancer cell apoptosis. PTL upregulated BAX, cleaved PARP-1, cleaved caspase-3, cleaved caspase-9, P53 and decreased the expression of BCL-2, phosphorylated ERK, and phosphorylated MEK in vitro. Tumour volume and weight were also suppressed by PTL in vivo. Moreover, the effects of PTL on GBC cells might be mediated by the MAPK pathway.

Conclusion

PTL significantly inhibits gallbladder cancer cell proliferation and induces apoptosis through the MAPK pathway, which is a potential molecular reagent for treating GBC. However, further exploration is needed to verify the antitumor effects of PTL and its intracellular signalling mechanism.

New Insights on NLRP3 Inflammasome: Mechanisms of Activation, Inhibition, and Epigenetic Regulation

Inflammasomes are important modulators of inflammation. Dysregulation of inflammasomes can enhance vulnerability to conditions such as neurodegenerative diseases, autoinflammatory diseases, and metabolic disorders. Among various inflammasomes, Nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) is the best-characterized inflammasome related to inflammatory and neurodegenerative diseases. NLRP3 is an intracellular sensor that recognizes pathogen-associated molecular patterns and damage-associated patterns resulting in the assembly and activation of NLRP3 inflammasome. The NLRP3 inflammasome includes sensor NLRP3, adaptor apoptosis-associated speck-like protein (ASC), and effector cysteine protease procaspase-1 that plays an imperative role in caspase-1 stimulation which further initiates a secondary inflammatory response. Regulation of NLRP3 inflammasome ameliorates NLRP3-mediated diseases. Much effort has been invested in studying the activation, and exploration of specific inhibitors and epigenetic mechanisms controlling NLRP3 inflammasome. This review gives an overview of the established NLRP3 inflammasome assembly, its brief molecular mechanistic activations as well as a current update on specific and non-specific NLRP3 inhibitors that could be used in NLRP3-mediated diseases. We also focused on the recently discovered epigenetic mechanisms mediated by DNA methylation, histone alterations, and microRNAs in regulating the activation and expression of NLRP3 inflammasome, which has resulted in a novel method of gaining insight into the mechanisms that modulate NLRP3 inflammasome activity and introducing potential therapeutic strategies for CNS disorders.

Molecular Mechanisms in Pathophysiology of Mucopolysaccharidosis and Prospects for Innovative Therapy

Mucopolysaccharidoses (MPSs) are a group of inborn errors of the metabolism caused by a deficiency in the lysosomal enzymes required to break down molecules called glycosaminoglycans (GAGs). These GAGs accumulate over time in various tissues and disrupt multiple biological systems, including catabolism of other substances, autophagy, and mitochondrial function. These pathological changes ultimately increase oxidative stress and activate innate immunity and inflammation. We have described the pathophysiology of MPS and activated inflammation in this paper, starting with accumulating the primary storage materials, GAGs. At the initial stage of GAG accumulation, affected tissues/cells are reversibly affected but progress irreversibly to: (1) disruption of substrate degradation with pathogenic changes in lysosomal function, (2) cellular dysfunction, secondary/tertiary accumulation (toxins such as GM2 or GM3 ganglioside, etc.), and inflammatory process, and (3) progressive tissue/organ damage and cell death (e.g., skeletal dysplasia, CNS impairment, etc.). For current and future treatment, several potential treatments for MPS that can penetrate the blood-brain barrier and bone have been proposed and/or are in clinical trials, including targeting peptides and molecular Trojan horses such as monoclonal antibodies attached to enzymes via receptor-mediated transport. Gene therapy trials with AAV, ex vivo LV, and Sleeping Beauty transposon system for MPS are proposed and/or underway as innovative therapeutic options. In addition, possible immunomodulatory reagents that can suppress MPS symptoms have been summarized in this review.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Inosine attenuates post-stroke neuroinflammation by modulating inflammasome mediated microglial activation and polarization

To date, various agents and molecules have been developed to treat post-stroke neuroinflammation; however, none of them are clinically successful. Post-stroke neuroinflammation is primarily attributed to microglial polarization as the generation of inflammasome complexes shifts microglia to their M1 phenotype and regulate the downstream cascade. Inosine, an adenosine derivative reported to maintain cellular energy homeostasis in stressed condition. Although, the exact mechanism is still unexplored, various studies have reported that it can stimulate axonal sprouting in different neurodegenerative diseases. Hence, our present study aims to decipher the molecular mechanism of inosine mediated neuroprotection by modulating inflammasome signaling towards altered microglial polarization in ischemic stroke. Inosine was administered intraperitoneally to male Sprague Dawley rats at 1 h post ischemic stroke and were further evaluated for neurodeficit score, motor coordination and long-term neuroprotection. Brains were harvested for infarct size estimation, biochemical assays and molecular studies. Inosine administration at 1 h post ischemic stroke decreased infarct size, neurodeficit score, and improved motor co-ordination. Normalization of biochemical parameters were achieved in the treatment groups. Microglial polarization towards its anti-inflammatory phenotype and modulation of inflammation were evident by relevant gene and protein expression studies. The outcome provides preliminary evidence of inosine mediated alleviation of post-stroke neuroinflammation via modulation of microglial polarization towards its anti-inflammatory form through regulating the inflammasome activation.

Nano Parthenolide Improves Intestinal Barrier Function of Sepsis by Inhibiting Apoptosis and ROS via 5-HTR2A

Background

Intestinal barrier dysfunction is an important complication of sepsis, while the treatment is limited. Recently, parthenolide (PTL) has attracted much attention as a strategy of sepsis, but whether nano parthenolide (Nano PTL) is therapeutic in sepsis-induced intestinal barrier dysfunction is obscured.

Methods

In this study, cecal ligation and puncture (CLP)-induced sepsis rats and lipopolysaccharide (LPS)-stimulated intestinal epithelial cells (IECs) were used to investigate the effect of PTL on intestinal barrier dysfunction. Meanwhile, we synthesized Nano PTL and compared the protective effect of Nano PTL with ordinary PTL on intestinal barrier function in septic rats and IECs. Network pharmacology and serotonin 2A (5-HTR2A) inhibitor were used to explore the mechanism of PTL on the intestinal barrier function of sepsis.

Results

The encapsulation rate of Nano PTL was 95±1.5%, the drug loading rate was 11±0.5%, and the average uptake rate of intestinal epithelial cells was 94%. Ordinary PTL and Nano PTL improved the survival rate and survival time of septic rats, reduced the mean arterial pressure and the serum level of inflammatory cytokines, and protected the liver and kidney functions in vivo, and increased the value of transmembrane resistance (TEER) reduced the reactive oxygen species (ROS) and apoptosis in IECs in vitro through 5-HTR2A. Nano PTL had better effect than ordinary PTL.

Conclusion

Ordinary PTL and Nano PTL can protect the intestinal barrier function of septic rats by inhibiting apoptosis and ROS through up-regulating 5-HTR2A, Nano PTL is better than ordinary PTL.

Parthenolide promotes expansion of Nestin+ progenitor cells via Shh modulation and contributes to post-injury cerebellar replenishment

Background: Regeneration of injuries occurring in the central nervous system is extremely difficult. Studies have shown that the developing cerebellum can be repopulated by a group of Nestin-expressing progenitors (NEPs) after irradiation injury, suggesting that modulating the mobilization of NEPs is beneficial to promoting nerve regeneration. To date, however, effect of exogenous pharmaceutical agonist on NEPs mobilization remains unknown. Parthenolide (PTL), a sesquiterpene lactone isolated from shoots of feverfew. Although it has been shown to possess several pharmacological activities and is considered to have potential therapeutic effects on the regeneration of peripheral nerve injury, its efficacy in promoting central nervous system (CNS) regeneration is unclear. In this study, we aimed to elucidate the role and possible mechanism of PTL on regeneration in injured CNS after irradiation using a developing cerebellum model. Methods: We investigated the radioprotective effects of PTL on the developing cerebellum by immunoblotting as well as immunofluorescence staining and ROS detection in vivo and in vitro experiments, and then determined the effects of PTL on NEPs in Nestin CFP and Nestin GFP fluorescent mice. Inducible lineage tracing analysis was used in Nestin-CreERT2×ROSA26-LSL YFP mice to label and track the fate of NEPs in the cerebellum after irradiation. Combined with cell biology and molecular biology techniques to determine changes in various cellular components in the cerebellum and possible mechanisms of PTL on NEPs mobilization in the injured developing cerebellum. Results: We found that PTL could attenuate radiation-induced acute injury of granule neuron progenitors (GNPs) in irradiated cerebellar external granule layer (EGL) by alleviating apoptosis through regulation of the cells' redox state. Moreover, PTL increased cerebellar Shh production and secretion by inhibiting the PI3K/AKT pathway, thus promoting expansion of NEPs, which is the compensatory replenishment of granule neurons after radiation damage. Conclusion: Collectively, our results indicate that activation and expansion of NEPs are critical for regeneration of the injured cerebellum, and that PTL is a promising drug candidate to influence this process.

Parthenolide modulates cerebral ischemia-induced microglial polarization and alleviates neuroinflammatory injury via the RhoA/ROCK pathway

BACKGROUND

Microglia can be activated as proinflammatory (M1) phenotypes and anti-inflammatory (M2) phenotypes after stroke. Parthenolide (PTL) has anti-inflammatory and protective effects on neurological diseases, but until now, the exact mechanisms of these processes after stroke have been unclear. The purpose of this study was to determine the effect of PTL on microglial polarization after stroke and its target for inducing microglial polarization.

METHODS

Triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and neurological evaluation were performed in a focal transient cerebral ischemia rat model. The human microglia exposed to lipopolysaccharide (LPS) was used for in vitro experiments. Microglial polarization was assessed by RT-PCR and immunostaining. Inflammatory cytokine assays and western blotting were used to investigate the molecular mechanisms underlying PTL-mediated microglial polarization in vivo and in vitro.

RESULTS

PTL significantly reduced cerebral infarction and neuronal apoptosis in rats with cerebral ischemia, reduced the level of inflammatory factors and alleviated neurological deficits. PTL treatment decreased the expression of microglia/macrophage markers in M1 macrophages and increased the expression of microglia/macrophage markers in M2 macrophages after stroke, which induced the transformation of microglia cells from the M1 phenotype to the M2 phenotype. Furthermore, PTL significantly reduced RhoA/ROCK-NF-κB pathway activity and downregulated the effects of pentanoic acid (ROCK agonist).

CONCLUSIONS

PTL has been shown to mediate neuroinflammation and protect against ischemic brain injury by regulating microglial polarization via the RhoA/ROCK pathway.

NF-κB and its crosstalk with endoplasmic reticulum stress in atherosclerosis

Atherosclerosis (AS) is a common cardiovascular disease with complex pathogenesis, in which multiple pathways and their interweaving regulatory mechanism remain unclear. The primary transcription factor NF-κB plays a critical role in AS via modulating the expression of a series of inflammatory mediators under various stimuli such as cytokines, microbial antigens, and intracellular stresses. Endoplasmic reticulum (ER) stress, caused by the disrupted synthesis and secretion of protein, links inflammation, metabolic signals, and other cellular processes via the unfolded protein response (UPR). Both NF-κB and ER stress share the intersection regarding their molecular regulation and function and are regarded as critical individual contributors to AS. In this review, we summarize the multiple interactions between NF-κB and ER stress activation, including the UPR, NLRP3 inflammasome, and reactive oxygen species (ROS) generation, which have been ignored in the pathogenesis of AS. Given the multiple links between NF-κB and ER stress, we speculate that the integrated network contributes to the understanding of molecular mechanisms of AS. This review aims to provide an insight into these interactions and their underlying roles in the progression of AS, highlighting potential pharmacological targets against the atherosclerotic inflammatory process.

The effect of parthenolide on methamphetamine-induced blood-brain barrier and astrocyte alterations

BACKGROUND

Methamphetamine abuse is a worldwide concern with long-term health complications. Its impact on neurons has been extensively investigated, and it is currently known that glial cells, including astrocytes, are involved in drug-induced outcomes. Importantly, METH also causes blood-brain barrier (BBB) disruption and astrocytes are critical for BBB (dys)function. Therefore, we aimed to clarify the involvement of neuroinflammation mediated by astrocytes in BBB permeability and brain oedema induced by METH. Further, we aimed to identify a new approach to counteract METH effects.

METHODS

Mice were administered with a METH binge regimen (4 × 10 mg/kg) alone or in combination with parthenolide (PTL; 4 × 1 mg/kg), and hippocampi were analysed. For in vitro studies, mouse primary cultures of astrocytes were exposed to 250 µM METH, alone or co-treated with 10 µM PTL.

RESULTS

We observed a neuroinflammatory response characterized by astrocytic morphological changes and increased TNF-α, iNOS and ICAM-1 protein levels (213.62%, 205.76% and 191.47% of control, respectively). Additionally, brain oedema and BBB disruption were identified by increased water content (81.30% of tissue weight) and albumin (224.40% of control) in the hippocampal tissue, as well as a significant decrease in vessel coverage by astrocytes after METH exposure. Regarding astrocyte cultures, we further identified TNF-α as a key player in METH-induced cell swelling. Importantly, PTL (present in feverfew plant) prevented both animal and in vitro effects induced by METH.

CONCLUSIONS

We provided important insights on brain dysfunction induced by METH, and we also suggest a new approach to counteract such negative effects.

Caspase-1: A Promising Target for Preserving Blood–Brain Barrier Integrity in Acute Stroke

The blood–brain barrier (BBB) acts as a physical and biochemical barrier that plays a fundamental role in regulating the blood-to-brain influx of endogenous and exogenous components and maintaining the homeostatic microenvironment of the central nervous system (CNS). Acute stroke leads to BBB disruption, blood substances extravasation into the brain parenchyma, and the consequence of brain edema formation with neurological impairment afterward. Caspase-1, one of the evolutionary conserved families of cysteine proteases, which is upregulated in acute stroke, mainly mediates pyroptosis and compromises BBB integrity via lytic cellular death and inflammatory cytokines release. Nowadays, targeting caspase-1 has been proven to be effective in decreasing the occurrence of hemorrhagic transformation (HT) and in attenuating brain edema and secondary damages during acute stroke. However, the underlying interactions among caspase-1, BBB, and stroke still remain ill-defined. Hence, in this review, we are concerned about the roles of caspase-1 activation and its associated mechanisms in stroke-induced BBB damage, aiming at providing insights into the significance of caspase-1 inhibition on stroke treatment in the near future.

Dexmedetomidine exerts a protective effect on ischemic brain injury by inhibiting the P2X7R/NLRP3/Caspase-1 signaling pathway

Dexmedetomidine (Dex) has been suggested to exert a protective function in ischemic brain injury. In this study, we aimed to elucidate the intrinsic mechanisms of Dex in regulating microglia pyroptosis in ischemic brain injury via the purinergic 2X7 receptor (P2X7R)/NLRP3/Caspase-1 signaling pathway. First, permanent middle cerebral artery occlusion (p-MCAO) rat model was established, followed by the measurement of behavioral deficit, neuronal injury, the volume of brain edema and the infarct size. Dex treatment was suggested to alleviate the neurological deficits in p-MCAO rats and reduce the brain water content and infarct size. Additionally, rat microglia were cultured in vitro and a model of oxygen and glucose (OGD) was established. Microglia cell activity and ultrastructure were detected. Dex could increase cell activity and reduce LDH activity, partially reversing the changes in cell morphology. Furthermore, the activation of P2X7R/NLRP3/Caspase-1 pathway was tested. The obtained findings indicated Dex suppressed microglial pyroptosis by inhibiting the P2X7R/NLRP3/Caspase-1 pathway. Inhibition of P2X7R or NLRP3 could inhibit Caspase-1 p10 expression, improve cell activity, and reduce LDH activity. The same result was verified in vivo experiments. This study indicated that Dex inhibited microglia pyroptosis by blocking the P2X7R/NLRP3/Caspase-1 pathway, thus playing a protective role against ischemic brain injury.

Role of Neuroinflammation and Blood-Brain Barrier Permutability on Migraine

Currently, migraine is treated mainly by targeting calcitonin gene-related peptides, although the efficacy of this method is limited and new treatment strategies are desired. Neuroinflammation has been implicated in the pathogenesis of migraine. In patients with migraine, peripheral levels of pro-inflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α, are known to be increased. Additionally, animal models of headache have demonstrated that immunological responses associated with cytokines are involved in the pathogenesis of migraine. Furthermore, these inflammatory mediators might alter the function of tight junctions in brain vascular endothelial cells in animal models, but not in human patients. Based on clinical findings showing elevated IL-1β, and experimental findings involving IL-1β and both the peripheral trigeminal ganglion and central trigeminal vascular pathways, regulation of the Il-1β/IL-1 receptor type 1 axis might lead to new treatments for migraine. However, the integrity of the blood-brain barrier is not expected to be affected during attacks in patients with migraine.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

Blocking the IL-1 receptor reduces cardiac transplant ischemia and reperfusion injury and mitigates CMV-accelerated chronic rejection

Ischemia-reperfusion injury (IRI) is an important risk factor for accelerated cardiac allograft rejection and graft dysfunction . Utilizing a rat heart isogeneic transplant model, we identified inflammatory pathways involved in IRI in order to identify therapeutic targets involved in disease. Pathway analyses identified several relevant targets, including cytokine signaling by the IL-1 receptor (IL-1R) pathway and inflammasome activation. To investigate the role of IL-1R signaling pathways during IRI, we treated syngeneic cardiac transplant recipients at 1-hour posttransplant with Anakinra, a US Food and Drug Administration (FDA)-approved IL-1R antagonist; or parthenolide, a caspase-1 and nuclear factor kappa-light-chain-enhancer of activated B cells inhibitor that blocks IL-1β maturation. Both Anakinra and parthenolide significantly reduced graft inflammation and cellular recruitment in the treated recipients relative to nontreated controls. Anakinra treatment administered at 1-hour posttransplant to recipients of cardiac allografts from CMV-infected donors significantly increased the time to rejection and reduced viral loads at rejection. Our results indicate that reducing IRI by blocking IL-1Rsignaling pathways with Anakinra or inflammasome activity with parthenolide provides a promising approach for extending survival of cardiac allografts from CMV-infected donors.

A decision process for drug discovery in retinoblastoma

Intraocular retinoblastoma treatment has changed radically over the last decade, leading to a notable improvement in ocular survival. However, eyes that relapse remain difficult to treat, as few alternative active drugs are available. More challenging is the scenario of central nervous system (CNS) metastasis, in which almost no advancements have been made. Both clinical scenarios represent an urgent need for new drugs. Using an integrated multidisciplinary approach, we developed a decision process for prioritizing drug selection for local (intravitreal [IVi], intrathecal/intraventricular [IT/IVt]), systemic, or intra-arterial chemotherapy (IAC) treatment by means of high-throughput pharmacological screening of primary cells from two patients with intraocular tumor and CNS metastasis and a thorough database search to identify clinical and biopharmaceutical data. This process identified 169 compounds to be cytotoxic; only 8 are FDA-approved, lack serious toxicities and available for IVi administration. Four of these agents could also be delivered by IT/IVt. Twelve FDA-approved drugs were identified for systemic delivery as they are able to cross the blood-brain barrier and lack serious adverse events; four drugs are of oral usage and six compounds that lack vesicant or neurotoxicity could be delivered by IAC. We also identified promising compounds in preliminary phases of drug development including inhibitors of survivin, antiapoptotic Bcl-2 family proteins, methyltransferase, and kinesin proteins. This systematic approach may be applied more broadly to prioritize drugs to be repurposed or to identify novel hits for use in retinoblastoma treatment.

Parthenolide promotes the repair of spinal cord injury by modulating M1/M2 polarization via the NF-κB and STAT 1/3 signaling pathway

Spinal cord injury (SCI) is a severe neurological disease; however, there is no effective treatment for spinal cord injury. Neuroinflammation involves the activation of resident microglia and the infiltration of macrophages is the major pathogenesis of SCI secondary injury and considered to be the therapeutic target of SCI. Parthenolide (PN) has been reported to exert anti-inflammatory effects in fever, migraines, arthritis, and superficial inflammation; however, the role of PN in SCI therapeutics has not been clarified. In this study, we showed that PN could improve the functional recovery of spinal cord in mice as revealed by increased BMS scores and decreased cavity of spinal cord injury in vivo. Immunofluorescence staining experiments confirmed that PN could promote axonal regeneration, increase myelin reconstitution, reduce chondroitin sulfate formation, inhibit scar hyperplasia, suppress the activation of A1 neurotoxic reactive astrocytes and facilitate shift from M1 to M2 polarization of microglia/macrophages. To verify how PN exerts its effects on microglia/macrophages polarization, we performed the mechanism study in vitro in microglia cell line BV-2. PN could significantly reduce M1 polarization in BV2 cells and partially rescue the decrease in the expression of M2 phenotype markers of microglia/macrophage induced by LPS, but no significant effect on M2 polarization stimulated with IL-4 was observed. Further study demonstrated PN inhibited NF-κB signal pathway directly or indirectly, and suppressed activation of signal transducer and activator of transcription 1 or 3 (STAT1/3) via reducing the expression of HDAC1 and subsequently increasing the levels of STAT1/3 acetylation. Overall, our study illustrated that PN may be a promising strategy for traumatic SCI.

Emerging role of IL-6 and NLRP3 inflammasome as potential therapeutic targets to combat COVID-19: Role of lncRNAs in cytokine storm modulation

The world has witnessed a high morbidity and mortality caused by SARS-CoV-2, and global death toll is still rising. Exaggerated inflammatory responses are thought to be more responsible for infiltrated immune cells accumulation, organ damage especially lung, dyspnea, and respiratory failure rather than direct effect of viral replication. IL-6 and NLRP3 inflammasome are the major immune components in immune responses stimulation upon pathogen infection. It's noteworthy that the function and expression of these components are remarkably influenced by non-coding RNAs including long non-coding RNAs. Given the potential role of these components in organ damage and pathological manifestations of patients infected with COVID-19, their blockage might be a hopeful and promising treatment strategy. Notably, more study on long non-coding RNAs involved in inflammatory responses could elevate the efficacy of anti-inflammatory therapy. In this review we discuss the potential impact of IL-6 and NLRP3 inflammasome blocker drugs on inflammatory responses, viral clearance, and pathological and clinical manifestations. Collectively, anti-inflammatory strategy might pave the way to diminish clinical and pathological manifestations and thereby discharging patients infected with COVID-19 from hospital.

Neuroinflammation Mediated by NLRP3 Inflammasome After Intracerebral Hemorrhage and Potential Therapeutic Targets

Intracerebral hemorrhage (ICH) is the most fatal subtype of stroke; there is still a lack of effective treatment. Microglia are a major component of the innate immune system, and they respond to acute brain injury by activating and forming classic M1-like (pro-inflammatory) or alternative M2-like (anti-inflammatory) phenotype. The existence of the polarization indicates that the role of microglia in disease's progression and recovery after ICH is still unclear, perhaps involving microglial secretion of anti-inflammatory or pro-inflammatory cytokines and chemokines. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is considered to be the main participant in neuroinflammation. Recent evidence has shown that NLRP3 inflammasome can be activated after ICH, resulting in inflammatory cascade reactions and aggravating brain injury. Furthermore, previous studies have reported that NLRP3 inflammasome is mainly present in microglia, so we speculate that its activation may be strongly associated with microglial polarization. Many scholars have investigated the role of brain injury caused by NLRP3 inflammasome after ICH, but the precise operating mechanisms remain uncertain. This review summarized the activation mechanism of NLRP3 inflammasome after ICH and the possible mechanism of NLRP3 inflammasome promoting neuroinflammation and aggravating nerve injury and discussed the relevant potential therapeutic targets.

Hypercapnia exacerbates the disruption of the blood‑brain barrier by inducing interleukin‑1β overproduction in the blood of hypoxemic adult rats

Refractory hypoxemia is the main symptom of acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is routinely applied in clinical practice to correct hypoxemia, which aims to prevent ventilator‑induced lung injury. However, this ventilation strategy inevitably leads to hypercapnia. Our previous study demonstrated that hypercapnia aggravated cognitive impairment in hypoxemic rats; however, the underlying mechanism remains unclear. The aim of the present study was to investigate whether hypercapnia exacerbates the blood‑brain barrier (BBB) disruption through inducing interleukin (IL)‑1β overproduction in the blood of hypoxemic rats. The BBB permeability in a rat model of hypercapnia/hypoxemia was evaluated. The levels of IL‑1β in the blood of rats and human whole‑blood cultures were assessed. The expression of IL‑1 receptor 1 (IL‑1R1), phosphorylated IL‑1R1‑associated kinase (p‑IRAK‑1) and tight junctional proteins in cerebral vascular endothelial cells was examined in vitro and in vivo. In addition, IL‑1Ra, an IL‑1 receptor antagonist, was used to determine whether hypercapnia affects tight junctional protein expression in hypoxic cerebral vascular endothelial cells through inducing IL‑1β overproduction. It was observed that hypercapnia alone did not disrupt the BBB, but aggravated the damage to the BBB integrity in hypoxemic rats. Hypercapnia increased IL‑1β expression in the blood of hypoxemic rats as well as in hypoxic human whole‑blood cultures. IL‑1R1 and p‑IRAK‑1 expression was increased, while that of tight junctional proteins was reduced by hypercapnia in hypoxemic cerebral vascular endothelial cells in vitro and in vivo. Additionally, the expression of tight junctional proteins was markedly increased following treatment with IL‑1Ra. These results suggest that hypercapnia‑induced IL‑1β overproduction in the hypoxemic blood may decrease tight junctional protein expression in cerebrovascular endothelial cells via the IL‑1R1/p‑IRAK‑1 pathway, further disrupting BBB integrity, and eventually resulting in increased BBB permeability.

Inflammasomes in neuroinflammatory and neurodegenerative diseases

Neuroinflammation and neurodegeneration often result from the aberrant deposition of aggregated host proteins, including amyloid‐β, α‐synuclein, and prions, that can activate inflammasomes. Inflammasomes function as intracellular sensors of both microbial pathogens and foreign as well as host‐derived danger signals. Upon activation, they induce an innate immune response by secreting the inflammatory cytokines interleukin (IL)‐1β and IL‐18, and additionally by inducing pyroptosis, a lytic cell death mode that releases additional inflammatory mediators. Microglia are the prominent innate immune cells in the brain for inflammasome activation. However, additional CNS‐resident cell types including astrocytes and neurons, as well as infiltrating myeloid cells from the periphery, express and activate inflammasomes. In this review, we will discuss current understanding of the role of inflammasomes in common degenerative diseases of the brain and highlight inflammasome‐targeted strategies that may potentially treat these diseases.

Lixisenatide Reduced Damage in Hippocampus CA1 Neurons in a Rat Model of Cerebral Ischemia-Reperfusion Possibly Via the ERK/P38 Signaling Pathway

Glucagon-like peptide-1 (GLP-1) is a gut-derived peptide that has various physiological actions. One of its main actions is the regulation of blood glucose level when it is elevated as it potentiates insulin release. It is also known that GLP-1 protects neurons from damage caused by neurodegenerative diseases. Lixisenatide is one of the GLP-1 analogues that has a strong affinity to the GLP-1 receptor. Experimental animal studies have shown that it holds a neuroprotective effect in Parkinson, myocardial, and cerebral ischemic disease animal models. The beneficial effect of lixisenatide on the brain after cerebral ischemia-reperfusion (I/R) is not clarified yet; thus, it needs further explanatory studies. Our research is the first to study the effect of lixisenatide on myeloperoxidase (MPO) and toll-like receptors (TLRs)/mitogen-activated protein kinase (MAPK) pathway in a rat model of cerebral I/R. Lixisenatide with 2 doses 0.7 and 7 nmol/kg was given intraperitoneal in 2 different groups for 14 days; then, the bilateral common carotid artery was occluded for 1 h followed by reperfusion for 1 h. Examination of hippocampus CA1 neurons by Nissl stain showed that the number of intact neurons was elevated in the lixisenatide-treated group related to the control group (I/R group). Lixisenatide exhibited neuroprotection action possibly via downregulation of MPO, TLR2/4, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and pP38 and upregulation of phosphorylated extracellular signal-regulated kinase (pERK1/2); thus, this study gives possible link between lixisenatide and TLR/MAPK pathway following cerebral I/R and supports the use of lixisenatide for neuroprotection against stroke.

Targeting the microglial NLRP3 inflammasome and its role in Parkinson's disease

Excessive activation of microglia and subsequent release of proinflammatory cytokines play a crucial role in neuroinflammation and neurodegeneration in Parkinson's disease (PD). Components of the nucleotide-binding oligomerization domain and leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome complex, leucine-rich-repeat- and pyrin-domain-containing 3, caspase-1, and apoptosis-associated speck-like protein containing a CARD, are highly expressed in activated microglia in PD patient brains. Findings suggest that neurotoxins, aggregation of α-synuclein, mitochondrial reactive oxygen species, and disrupted mitophagy are the key regulators of microglial leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome activation and release of interleukin-1β and interleukin-18 caspase-1-mediated pyroptotic cell death in the substantia nigra of the brain. Although this evidence suggests the leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome may be a potential drug target for treatment of PD, the exact mechanism of how the microglia sense these stimuli and initiate leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome signaling is unknown. Here, the molecular mechanism and regulation of microglial leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome activation and its role in the pathogenesis of PD are discussed. Moreover, the potential of both endogenous and synthetic leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome modulators, long noncoding RNA, microRNA to develop novel therapeutics to treat PD is presented. Overall, we recommend that the microglial leucine-rich-repeat- and pyrin-domain-containing 3 inflammasome can be a potential target for PD treatment. © 2019 International Parkinson and Movement Disorder Society.

Involvement of mitochondrial apoptotic pathway and MAPKs/NF-κ B inflammatory pathway in the neuroprotective effect of atractylenolide III in corticosterone-induced PC12 cells

Atractylenolide III (ATL-III), a sesquiterpene compound isolated from Rhizoma Atractylodis Macrocephalae, has revealed a number of pharmacological properties including anti-inflammatory, anti-cancer activity, and neuroprotective effect. This study aimed to evaluate the cytoprotective efficiency and potential mechanisms of ATL-III on corticosterone injured rat phaeochromocytoma (PC12) cells. Our results demonstrate that ATL-III increases cell viability and reduces the release of lactate dehydrogenase (LDH). The results suggest that ATL-III protects PC12 cells from corticosterone-induced injury by inhibiting the intracellular Ca²⁺ overloading, inhibiting the mitochondrial apoptotic pathway and modulating the MAPK/NF-ΚB inflammatory pathways. These findings provide a novel insight into the molecular mechanism by which ATL-III protected the PC12 cells against corticosterone-induced injury for the first time. Our results provide the evidence that ATL-III may serve as a therapeutic agent in the treatment of depression.

Parthenolide ameliorates intracerebral hemorrhage-induced brain injury in rats

Neuroinflammation and oxidative stress are key contributors to intracranial hemorrhage (ICH)-induced brain injury. Parthenolide (PN) is a sesquiterpene lactone that has been observed to have antioxidative, anti-inflammatory, and neuroprotective potentials. However, the role of PN in ICH remains unclear. Therefore, we investigated the neuroprotective effects and underlying mechanisms of PN on an experimental model of ICH in rats. Our results showed that PN treatment improved neurological deficit and brain edema in ICH rats. The ipsilateral hemispheres of the brain were separated and homogenized. The concentrations of TNF-α, interleukin (IL)-6, and IL-17 in the homogenates were detected by enzyme-linked immunosorbent assay. We found that PN inhibited the production of proinflammatory cytokines in an ICH rat model. The ROS and glutathione (GSH) levels, as well as the activity of superoxide dismutase (SOD) in the homogenates were measured. ICH caused an increase in ROS level, and the decreases in GSH level and SOD activity were mitigated by PN treatment. Furthermore, PN significantly suppressed the expressions of active caspase-3 and Bax in ipsilateral hemispheres of the brain at Day 3 after ICH, as well as increased the surviving neurons. Finally, the ICH-induced activation of TLR4/NF-κB pathway was suppressed by PN treatment. These findings suggested that PN could be beneficial in the therapeutic strategy for ICH treatment.

Bicyclic eremophilane-type petasite sesquiterpenes potentiate peroxisome proliferator-activated receptor γ activator-mediated inhibition of dendritic cells

Dendritic cell (DC) activation induces expression of co-stimulatory surface molecules, as well as migration into secondary lymphoid organs, where they activate naïve T-cells. A family of plant derivatives, eremophilane-type petasite sesquiterpenes, can regulate the immune system through DC targeting due to their anti-inflammatory effects. Peroxisome proliferator–activated receptor gamma (PPARγ) is involved in inhibition of inflammatory responses and induction of DCs to acquire a mucosal phenotype. Since mucosal DCs are central in innate immune responses, we hypothesized that eremophilane-type petasite sesquiterpenes exerted their anti-inflammatory effects by inhibiting DC maturation and activation through PPARγ. This study assessed the bicyclic eremophilane-type petasite sesquiterpene compounds Fukinone and 10βH-8α,12-Epidioxyeremophil-7(11)-en-8β-ol (ZYFDC21 and ZYFDC22) in the maturation and activation of mouse DC. We measured surface expression of co-stimulatory molecules by flow cytometry and cell-free supernatant cytokine production upon lipopolysaccharide stimulation by enzyme-linked immunosorbent assays (ELISAs) in the presence or absence of PPARγ agonists. DCs were generated from C57BL/6 mice bone marrow cells and harvested. Cells were exposed to bicyclic eremophilane-type petasite sesquiterpenes ZYFDC21 or ZYFDC22 in the presence or absence of synthetic PPARγ agonists (GW1929 and TGZ) or the natural PPARγ ligand 15d-PGJ₂, followed by overnight activation with LPS. We observed differences in the upregulation of surface expression of CD86, along with TNF, IL-6, and IL-12p70 released by DCs stimulated with LPS, when using combinations of bicyclic eremophilane-type petasite sesquiterpenes ZYFDC21 or ZYFDC22, and PPARγ agonists, in particular the PPARγ ligand 15d-PGJ₂. Our results indicate that bicyclic eremophilane-type petasite sesquiterpenes ZYFDC21 or ZYFDC22 inhibit maturation and activation of DC, and this activity is augmented upon PPARγ activation.

(-)-α-bisabolol prevents neuronal damage and memory deficits through reduction of proinflammatory markers induced by permanent focal cerebral ischemia in mice

The pathophysiology of ischemic stroke involves multiple events such as inflammation and oxidative stress which will lead to neuronal death and cognitive deficits. The (-)-α-bisabolol is a monocyclic sesquiterpene alcohol found in various plants and mainly in Matricaria chamomilla, which exerts antioxidant, anti-inflammatory, and anti-apoptotic activities. The aim of this work was to investigate the neuroprotective effects of (-)-α-bisabolol in mice underwent permanent occlusion of the middle cerebral artery (pMCAO). Animals were treated with (-)-α-bisabolol (50, 100 and 200 mg/kg/day, orally) or vehicle (3% tween 80) one day before and 1 h after pMCAO and the treatment continued once daily for the following five days. The treatment with (-)-α-bisabolol (100 and 200 mg/kg) significantly reduced the infarcted area and neurological deficits caused by pMCAO. (-)-α-bisabolol at the 200 mg/kg dose increased cell viability and decreased neuronal degeneration, as evaluated by cresyl violet and Fluoro-Jade C stainings, respectively. (-)-α-bisabolol also increased the locomotor activity which was reduced by cerebral ischemia and improved pMCAO-induced working, spatial, object recognition, and aversive memories deficits. (-)-α-bisabolol (200 mg/kg) significantly prevented the increase of myeloperoxidase (MPO) activity, TNF-α immunoreactivity in the temporal cortex, and the increase of iNOS both in the temporal cortex and in the striatum. (-)-α-bisabolol treatment also prevented astrogliosis in these areas. These data showed that (-)-α-bisabolol provides neuroprotective action probably due to its anti-inflammatory activity, although other mechanisms cannot be discarded.

β-amyloid cytotoxicity is prevented by natural achillolide A

Alzheimer's disease (AD) is the most prevalent cause of dementia in adults. Current available drugs for AD transiently alleviate some of the symptoms, but do not modify the disease mechanism or cure it. Therefore, new drugs are desperately needed. Key contributors to AD are amyloid beta (Aβ)- and reactive oxygen species (ROS)-induced cytotoxicities. Plant-derived substances have been shown to affect various potential targets in various diseases including AD. Therefore, phytochemicals which can protect neuronal cells against these insults might help in preventing and treating this disease. In the following research, we have isolated the sesquiterpene lactone achillolide A from the plant Achillea fragrantissima and, for the first time, characterized its effects on Aβ-treated neuroblastoma cells. Aβ is a peptide derived from the sequential cleavage of amyloid precursor protein, and is part of the pathogenesis of AD. Our current study aimed to determine whether achillolide A can interfere with Aβ-induced processes in Neuro2a cells, and protect them from its toxicity. Our results show that achillolide A decreased Aβ-induced death and enhanced the viability of Neuro2a cells. In addition, achillolide A reduced the accumulation of Aβ-induced ROS and inhibited the phosphorylation of stress-activated protein kinase/c-Jun N-terminal kinase and p44/42 mitogen-activated protein kinase in these cells. We therefore suggest that achillolide A may have therapeutic potential for the treatment of AD.

Parthenolide attenuates cerebral ischemia/reperfusion injury via Akt/GSK-3β pathway in PC12 cells

Parthenolide (PN), a sesquiterpene lactone isolated from the herbal medicine feverfew (Tanacetum parthenium), was reported to possess neuroprotective activity. However, the neuroprotective effect of PN against cerebral ischemia/reperfusion (I/R) injury remains unclear. Therefore, the aim of the present study was to explore the neuroprotective effects of PN against oxygen-glucose deprivation (OGD)-induced apoptosis in PC12 cells and the underlying mechanisms. Our results demonstrated that PN ameliorated OGD/R-evoked neuronal injury and oxidative stress in PC12 cells. In addition, PN notably decreased HIF-1α expression, as well as inhibited apoptosis in PC12 cells after OGD/R. Furthermore, PN pretreatment significantly enhanced the phosphorylation of Akt and GSK-3β in PC12 cells exposed to OGD/R. In conclusion, the present study demonstrated that PN exhibits a neuroprotective effect against OGD/R through activation of the Akt/GSK-3β signaling pathway. Our findings suggest that PN has the potential to serve as a novel therapeutic agent for cerebral I/R injury.

Alantolactone and Isoalantolactone Prevent Amyloid β25-35 -induced Toxicity in Mouse Cortical Neurons and Scopolamine-induced Cognitive Impairment in Mice

Given the evidence for detoxifying/antioxidant enzyme-inducing activities by alantolactone (AL) and isoalantolactone (IAL), the purpose of this study was to investigate the effects of AL and IAL on Aβ_25-35 -induced cell death in mouse cortical neuron cells and to determine their effects on scopolamine-induced amnesia in mice. Our data demonstrated that both compounds effectively attenuated the cytotoxicity of Aβ_25-35 (10 μM) in neuronal cells derived from the mouse cerebral cortex. It was also found that the production of intracellular reactive oxygen species, including superoxide anion induced by Aβ_25-35 , was inhibited. Moreover, the administration of the sesquiterpenes reversed scopolamine-induced cognitive impairments as assessed by Morris water, Y-maze, and the passive avoidance tests, and the compounds decreased acetylcholinesterase (AChE) activities in a dose-dependent manner. Interestingly, AL and IAL did not improve scopolamine-induced cognitive deficit in Nrf2^-/- mice, suggesting that memory improvement by sesquiterpenes was mediated not only by the activation of the Nrf2 signaling pathway but also by their inhibitory activity against AChE. In conclusion, our results showed that AL and IAL had neuroprotective effects and reversed cognitive impairments induced by scopolamine in a mouse model. Therefore, AL and IAL deserve further study as potential therapeutic agents for reactive oxygen species-related neurodegenerative diseases. Copyright © 2017 John Wiley & Sons, Ltd.

N-Butylphthalide Alleviates Blood-Brain Barrier Impairment in Rats Exposed to Carbon Monoxide

Carbon monoxide (CO) poisoning is one of the most important health concerns and may result in neuropathologic changes and neurologic sequelae. However, few studies have addressed the correlation between CO poisoning and blood–brain barrier (BBB) impairment. In this study, we investigated the effects of N-butylphthalide (NBP) on the expressions of zonula occludens-1 (ZO-1), claudin-5 and aquaporin-4 (AQP-4) proteins in a CO poisoning rat model. The results indicated that the brain water content was obviously increased, and the tight junctions between endothelial cells were disrupted, resulting in significant cerebral edema and BBB dysfunction in a rat model of CO poisoning. Meanwhile, the ultrastructure of endothelial cells and pericytes was seriously damaged, and the expressions of ZO-1 and claudin-5 were decreased at an early stage (<7 days). NBP treatment could efficiently maintain the ultrastructural and functional integrity of BBB, alleviate cerebral edema. Besides, NBP could also markedly increase the levels of both ZO-1 and claudin-5 proteins compared with those in rats exposed to CO (P < 0.05), whereas NBP had no apparent regulatory effect on AQP-4 expression. Taken together, this study highlights the importance of ZO-1 and claudin-5 proteins in maintaining BBB ultrastructure and function after CO poisoning. NBP, as a novel treatment approach, may effectively inhibit the down-regulation of ZO-1 and claudin-5 proteins (but not AQP-4), thereby preserving the barrier function and reducing cerebral edema after CO poisoning.

Parthenolide, an NF-κB Inhibitor Ameliorates Diabetes-Induced Behavioural Deficit, Neurotransmitter Imbalance and Neuroinflammation in Type 2 Diabetes Rat Model

Diabetes is associated with behavioural and neurochemical alterations. In this manuscript, we are reporting the beneficial effects of parthenolide, an NF-κB inhibitor on behavioural and neurochemical deficits in type 2 diabetic rat model. Diabetes was induced by high-fat diet followed by low dose of streptozotocin (35 mg/kg). Elevated plus maze, open-field, MWM and passive avoidance test paradigm were used to assess behavioural and cognitive deficits. Three-week treatment of parthenolide (0.25 and 0.50 mg/kg; i.p.) attenuated diabetes-induced alteration in cognitive function in Morris water maze and passive avoidance test. Anxiety-like behaviour was also reduced by parthenolide treatment. Moreover, TNF-α and IL-6 levels were significantly decreased in cortex and hippocampus of parthenolide-treated rats. Three-week parthenolide treatment also toned down the alteration of GABA and glutamate homoeostasis. Results of this study corroborate the involvement of neuroinflammation in the development of behavioural and neurochemical deficits in diabetic animals and point towards the therapeutic potential of parthenolide in diabetes-induced alteration of learning, memory and anxiety behaviour.

5-LOX Inhibitor Zileuton Reduces Inflammatory Reaction and Ischemic Brain Damage Through the Activation of PI3K/Akt Signaling Pathway

Previous studies from our laboratories showed that an anti-inflammatory drug, 5-lipoxygenase inhibitor zileuton, attenuates ischemic brain damage via inhibiting inflammatory reaction. However, it was elusive whether zileuton attenuates inflammatory reaction and ischemic brain damage through the modulation of PI3K/Akt signaling pathway. In the present study, we, for the first time, investigated whether PI3K/Akt pathway was involved in zileuton's anti-inflammatory and neuroprotective properties against brain damage following experimental ischemic stroke. Adult male Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAO), then received treatment with zileuton or vehicle after the onset of ischemia. LY294002 was injected intracerebroventricularly to inhibit the activation of PI3K/Akt signaling pathway selectively. Neurological deficit scores, cerebral infarct volume, morphological characteristic and cerebral water content were assessed 24 h after cerebral ischemia. The enzymatic activity of myeloperoxidase (MPO) was measured 24 h after cerebral ischemia. Expression of p-Akt, t-Akt and COX-2 in ischemic brain were determined by western blot. NF-κB p65 immuno-positive cells in ischemic brain were detected 24 h after cerebral ischemia. The content of TNF-α in blood was examined by ELISA. 5-LOX inhibitor zileuton significantly reduces neurological deficit scores, cerebral infarct volume, cerebral water content, ischemic neuronal injury and the enzymatic activity of MPO, all of which were abolished by LY294002 administration. Zileuton significantly up-regulates the expression of p-Akt, which was inhibited by LY294002 administration. Zileuton significantly down-regulates the over-expression of NF-κB p65 and COX-2, and attenuates the release of TNF-α, all of which were disminished by LY294002 administration. These results suggest that zileuton attenuates ischemic brain damage by inhibiting inflammatory reaction through the activation of PI3K/Akt signaling pathway.

Melatonin Preserves Blood-Brain Barrier Integrity and Permeability via Matrix Metalloproteinase-9 Inhibition

Microvascular hyperpermeability that occurs at the level of the blood-brain barrier (BBB) often leads to vasogenic brain edema and elevated intracranial pressure following traumatic brain injury (TBI). At a cellular level, tight junction proteins (TJPs) between neighboring endothelial cells maintain the integrity of the BBB via TJ associated proteins particularly, zonula occludens-1 (ZO-1) that binds to the transmembrane TJPs and actin cytoskeleton intracellularly. The pro-inflammatory cytokine, interleukin-1β (IL-1β) as well as the proteolytic enzymes, matrix metalloproteinase-9 (MMP-9) are key mediators of trauma-associated brain edema. Recent studies indicate that melatonin a pineal hormone directly binds to MMP-9 and also might act as its endogenous inhibitor. We hypothesized that melatonin treatment will provide protection against TBI-induced BBB hyperpermeability via MMP-9 inhibition. Rat brain microvascular endothelial cells grown as monolayers were used as an in vitro model of the BBB and a mouse model of TBI using a controlled cortical impactor was used for all in vivo studies. IL-1β (10 ng/mL; 2 hours)-induced endothelial monolayer hyperpermeability was significantly attenuated by melatonin (10 μg/mL; 1 hour), GM6001 (broad spectrum MMP inhibitor; 10 μM; 1 hour), MMP-9 inhibitor-1 (MMP-9 specific inhibitor; 5 nM; 1 hour) or MMP-9 siRNA transfection (48 hours) in vitro. Melatonin and MMP-9 inhibitor-1 pretreatment attenuated IL-1β-induced MMP-9 activity, loss of ZO-1 junctional integrity and f-actin stress fiber formation. IL-1β treatment neither affected ZO-1 protein or mRNA expression or cell viability. Acute melatonin treatment attenuated BBB hyperpermeability in a mouse controlled cortical impact model of TBI in vivo. In conclusion, one of the protective effects of melatonin against BBB hyperpermeability occurs due to enhanced BBB integrity via MMP-9 inhibition. In addition, acute melatonin treatment provides protection against BBB hyperpermeability in a mouse model of TBI indicating its potential as a therapeutic agent for brain edema when established in humans.

Therapeutics targeting the inflammasome after central nervous system injury

Innate immunity is part of the early response of the body to deal with tissue damage and infections. Because of the early nature of the innate immune inflammatory response, this inflammatory reaction represents an attractive option as a therapeutic target. The inflammasome is a component of the innate immune response involved in the activation of caspase 1 and the processing of pro-interleukin 1β. In this article, we discuss the therapeutic potential of the inflammasome after central nervous system (CNS) injury and stroke, as well as the basic knowledge we have gained so far regarding inflammasome activation in the CNS. In addition, we discuss some of the therapies available or under investigation for the treatment of brain injury, spinal cord injury, and stroke.

Cinnamaldehyde inhibits inflammation and brain damage in a mouse model of permanent cerebral ischaemia

BACKGROUND AND PURPOSE

Recent findings suggest the importance of inflammation in the pathogenesis of cerebral ischaemia and its potential as a therapeutic target. Cinnamaldehyde is a diterpene with a wide range of anti-inflammatory effects thus may be advantageous in the treatment of cerebral ischaemia. The present study examined the potential therapeutic effects of cinnamaldehyde on cerebral ischaemia using a mouse model with permanent middle cerebral artery occlusion.

EXPERIMENTAL APPROACH

Male CD-1 mice, which had the middle cerebral artery occluded, were treated (i.p.) with cinnamaldehyde. Neuroprotection by cinnamaldehyde was analysed by evaluating neurological deficit scores, brain oedema and infarct volume. Expressions of signal transduction molecules and inflammatory mediators were measured by Western blotting, qRT-PCR and immunohistochemical staining. Activation of NF-κB was assessed by Western blotting, immunohistochemistry and immunofluorescence.

KEY RESULTS

Cinnamaldehyde reduced the neurological deficit scores, brain oedema and infarct volume. Cinnamaldehyde suppressed the activation of signal transduction molecules including toll-like receptor 4, tumour necrosis receptor-associated factor 6 and NF-κB, attenuated the increased levels of TNF-α, IL-1β, CCL2 and endothelial-leukocyte adhesion molecule-1 and ultimately reduced leukocyte infiltration into the ischaemic brain areas after cerebral ischaemia.

CONCLUSIONS AND IMPLICATIONS

Cinnamaldehyde protects against cerebral ischaemia injury by inhibiting inflammation, partly mediated by reducing the expression of toll-like receptor 4, tumour necrosis receptor-associated factor 6 and the nuclear translocation of NF-κB. Our findings suggest that cinnamaldehyde may serve as a new candidate for further development as a treatment for stroke.

Inhibiting the Inflammasome: A Chemical Perspective

Inflammasomes are high molecular weight complexes that sense and react to injury and infection. Their activation induces caspase-1 activation and release of interleukin-1β, a pro-inflammatory cytokine involved in both acute and chronic inflammatory responses. There is increasing evidence that inflammasomes, particularly the NLRP3 inflammasome, act as guardians against noninfectious material. Inappropriate activation of the NLRP3 inflammasome contributes to the progression of many noncommunicable diseases such as gout, type II diabetes, and Alzheimer's disease. Inhibiting the inflammasome may significantly reduce damaging inflammation and is therefore regarded as a therapeutic target. Currently approved inhibitors of interleukin-1β are rilonacept, canakinumab, and anakinra. However, these proteins do not possess ideal pharmacokinetic properties and are unlikely to easily cross the blood-brain barrier. Because inflammation can contribute to neurological disorders, this review focuses on the development of small-molecule inhibitors of the NLRP3 inflammasome.

Repetitive ischemic preconditioning attenuates inflammatory reaction and brain damage after focal cerebral ischemia in rats: involvement of PI3K/Akt and ERK1/2 signaling pathway

Ischemic preconditioning (IPC) has been demonstrated to provide a neuroprotection against brain damage produced by focal cerebral ischemia. However, it is elusive whether ischemic preconditioning attenuates ischemic brain damage through modulating phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. In the present study, we first explored the best scheme of repetitive ischemic preconditioning (RIPC) to protect rat brain against ischemic damage and then further investigated the underlying mechanisms in RIPC's neuroprotection. Adult male Sprague-Dawley rats underwent ischemic preconditioning or (and) middle cerebral artery occlusion (MCAO). LY294002 or (and) PD98059 were injected intracerebroventricularly to selectively inhibit the activation of PI3K/Akt or ERK1/2. Neurological deficit scores, cerebral infarct volume, and morphological characteristic were detected at corresponding time after cerebral ischemia. The enzymatic activity of myeloperoxidase (MPO) was measured 24 h after cerebral ischemia. Expressions of p-Akt, t-Akt, p-ERK1/2, t-ERK1/2, nuclear factor-kappa B (NF-κB) p65, and cyclooxygenase-2 (COX-2) in ischemic brain were determined by Western blot. The release of tumor necrosis factor-α (TNF-α) in blood was examined by ELISA. In the various schemes of RIPC, IPC2 × 5 min causes less neuronal damage in the cortex and subcortex of ischemic brain and provides an obvious alleviation of cerebral infarction and neurological deficit after lethal ischemia. IPC2 × 5 min significantly reduces cerebral infarct volume, neurological deficit scores, and MPO activity; all of which were diminished by LY294002 or (and) PD98059. IPC2 × 5 min significantly upregulates the expressions of p-Akt and p-ERK1/2, which were inhibited by LY294002 or (and) PD98059. IPC2 × 5 min significantly downregulates the expressions of NF-κB p65 and COX-2 and attenuates the release of TNF-α; all of which were abolished by LY294002 or (and) PD98059. IPC2 × 5 min is the best scheme of RIPC to protect rat brain against cerebral ischemia. IPC2 × 5 min attenuates brain damage in rats subjected to lethal ischemia, and this neuroprotection is associated with inhibition of neuroinflammation through modulating PI3K/Akt and ERK1/2 signaling pathway.

Neuroprotection of atractylenolide III from Atractylodis macrocephalae against glutamate-induced neuronal apoptosis via inhibiting caspase signaling pathway

Glutamate-induced excitotoxicity appears to play a crucial role in neurological disorders. Neuroprotection against glutamate-induced excitotoxicity has been proposed as a therapeutic strategy for preventing and/or treating these excitotoxicity-mediated diseases. In the present study, atractylenolide III, which exhibited significantly neuroprotective effect against glutamate-induced neuronal apoptosis, was isolated from Atractylodes macrocephala by means of bioactivity-guided fractionation. The inhibitory effect of atractylenolide III on glutamate-induced neuronal apoptosis was in a concentration-dependent manner. The anti-apoptotic property of atractylenolide III might be mediated, in part, via inhibiting caspase signaling pathway. Atractylenolide III may have therapeutic potential in excitotoxicity-mediated neurological diseases.

Herbal medicines for ischemic stroke: combating inflammation as therapeutic targets

Stroke is a debilitating disease for which limited therapeutic approaches are available currently. Thus, there is an urgent need for developing novel therapies for stroke. Astrocytes, endothelial cells and pericytes constitute a neurovascular network for metabolic requirement of neurons. During ischemic stroke, these cells contribute to post-ischemic inflammation at multiple stages of ischemic cascades. Upon ischemia onset, activated resident microglia and astrocytes, and infiltrated immune cells release multiple inflammation factors including cytokines, chemokines, enzymes, free radicals and other small molecules, not only inducing brain damage but affecting brain repair. Recent progress indicates that anti-inflammation is an important therapeutic strategy for stroke. Given a long history with direct experience in the treatment of human subjects, Traditional Chinese Medicine and its related natural compounds are recognized as important sources for drug discovery. Last decade, a great progress has been made to identify active compounds from herbal medicines with the properties of modulating post-ischemic inflammation for neuroprotection. Herein, we discuss the inflammatory pathway in early stage and secondary response to injured tissues after stroke from initial artery occlusion to brain repair, and review the active ingredients from natural products with anti-inflammation and neuroprotection effects as therapeutic agents for ischemic stroke. Further studies on the post-ischemic inflammatory mechanisms and corresponding drug candidates from herbal medicine may lead to the development of novel therapeutic strategies in stroke treatment.