Tetrandrine suppresses amyloid-β-induced inflammatory cytokines by inhibiting NF-κB pathway in murine BV2 microglial cells

Olanzapine attenuates amyloid-β-induced microglia-mediated progressive neurite lesions

The accumulation of amyloid-β (Aβ) in the brain is the first pathological mechanism to initiate Alzheimer's disease (AD) pathogenesis. However, the precise role of Aβ in the disease progression remains unclear. Through decades of research, prolonged inflammation has emerged as an important core pathology in AD. Previously, a study has demonstrated the neurotoxic effect of Aβ-induced neuroinflammation in neuron-glia co-culture at 72 h. Here, we hypothesise that initial stage Aβ may trigger microglial inflammation, synergistically contributing to the progression of neurite lesions relevant to AD progression. In the present study, we aimed to determine whether olanzapine, an antipsychotic drug possessing anti-inflammatory properties, can ameliorate Aβ-induced progressive neurite lesions. Our study reports that Aβ induces neurite lesions with or without inflammatory microglial cells in vitro. More intriguingly, the present study revealed that Aβ exacerbates neurite lesions in synergy with microglia. Moreover, the time course study revealed that Aβ promotes microglia-mediated neurite lesions by eliciting the secretion of pro-inflammatory cytokines. Furthermore, our study shows that olanzapine at lower doses prevents Aβ-induced microglia-mediated progressive neurite lesions. The increase in pro-inflammatory cytokines induced by Aβ is attenuated by olanzapine administration, associated with a reduction in microglial inflammation. Finally, this study reports that microglial senescence induced by Aβ was rescued by olanzapine. Thus, our study provides the first evidence that 1 µM to 5 µM of olanzapine can effectively prevent Aβ-induced microglia-mediated progressive neurite lesions by modulating microglial inflammation. These observations reinforce the potential of targeting microglial remodelling to slow disease progression in AD.

Development of Novel Herbal Compound Formulations Targeting Neuroinflammation: Network Pharmacology, Molecular Docking, and Experimental Verification

Neuroinflammation plays an important role in the onset and progression of neurodegenerative diseases. The multicomponent and multitarget approach may provide a practical strategy to address the complex pathological mechanisms of neuroinflammation. This study aimed to develop synergistic herbal compound formulas to attenuate neuroinflammation using integrated network pharmacology, molecular docking, and experimental bioassays. Eight phytochemicals with anti-neuroinflammatory potential were selected in the present study. A compound-gene target-signaling pathway network was constructed to illustrate the mechanisms of action of each phytochemical and the interactions among them at the molecular level. Molecular docking was performed to verify the binding affinity of each phytochemical and its key gene targets. An experimental study was conducted to identify synergistic interactions among the eight phytochemicals, and the associated molecular mechanisms were examined by immunoblotting based on the findings from the network pharmacology analysis. Two paired combinations, andrographolide and 6-shogaol (AN-SG) (IC50 = 2.85 μg/mL), and baicalein-6-shogaol (BA-SG) (IC50 = 3.28 μg/mL), were found to synergistically (combination index <1) inhibit the lipopolysaccharides (LPS)-induced nitric oxide production in microglia N11 cells. Network pharmacology analysis suggested that MAPK14, MAPK8, and NOS3 were the top three relevant gene targets for the three phytochemicals, and molecular docking demonstrated strong binding affinities of the phytochemicals to their coded proteins. Immunoblotting suggested that the AN-SG and BA-SG both showed prominent effects in inhibiting inducible nitric oxide synthase (iNOS) (p < 0.01 and p < 0.05, respectively) and MAPKp-p38 (both p < 0.05) compared with those induced by the LPS stimulation only. The AN-SG combination exhibited greater inhibitions of the protein expressions of iNOS (p < 0.05 vs. individual components), which may partly explain the mechanisms of the synergy observed. This study established a practical approach to developing novel herbal-compound formulations using integrated network pharmacology analysis, molecular docking, and experimental bioassays. The study provides a scientific basis and new insight into the two synergistic combinations against neuroinflammation.

Tetrandrine alleviates inflammation and neuron apoptosis in experimental traumatic brain injury by regulating the IRE1α/JNK/CHOP signal pathway

AIM

The aim of this study was to investigate the therapeutic roles of Tetrandrine (TET) on traumatic brain injury (TBI) and the underlying mechanism.

METHOD

Traumatic injury model of hippocampal neurons and TBI mouse model were established to evaluate the therapeutic effects. The expression of neuron-specific enolase (NSE), Caspase 3, and Caspase 12 was detected by immunofluorescence. The expression of TNF-α, NF-κB, TRAF1, ERS markers (GADD34 and p-PERK), IRE1α, CHOP, JNK, and p-JNK were evaluated by western blot. Flow cytometry was used to determine the apoptosis of neurons. Brain injury was assessed by Garcia score, cerebral water content, and Evan blue extravasation test. Hematoxylin and eosin staining was used to determine the morphological changes of hippocampal tissue. Apoptosis was assessed by TUNEL staining.

RESULT

In traumatic injury model of hippocampal neurons, TET downregulated NSE, TNF-α, NF-κB, TRAF1, GADD34, p-PERK, IRE1α, CHOP, and p-JNK expression. TET reduced Caspase 3 and Caspase 12 cleavage. Apoptosis rate was inhibited by the introduction of TET. TET improved the Garcia neural score, decreased the cerebral water content and Evans blue extravasation, and reduced NSE, TNF-α, NF-κB, TRAF1, IRE1α, CHOP, and p-JNK expression in mice with TBI, which was significantly reversed by Anisomycin, a JNK selective activator.

CONCLUSION

TET alleviated inflammation and neuron apoptosis in experimental TBI by regulating the IRE1α/JNK/CHOP signal pathway.

Progress on structural modification of Tetrandrine with wide range of pharmacological activities

Tetrandrine (Tet), derived from the traditional Chinese herb Fangji, is a class of natural alkaloids with the structure of bisbenzylisoquinoline, which has a wide range of physiological activities and significant pharmacfological effects. However, studies and clinical applications have revealed a series of drawbacks such as its poor water solubility, low bioavailability, and the fact that it can be toxic to humans. The results of many researchers have confirmed that chemical structural modifications and nanocarrier delivery can address the limited application of Tet and improve its efficacy. In this paper, we summarize the anti-tumor efficacy and mechanism of action, anti-inflammatory efficacy and mechanism of action, and clinical applications of Tet, and describe the progress of Tet based on chemical structure modification and nanocarrier delivery, aiming to explore more diverse structures to improve the pharmacological activity of Tet and provide ideas to meet clinical needs.

Prominent Effects of Berbamine Hydrochloride on Alzheimer’s Disease Model Mice

Very few anti-Alzheimer’s disease (AD) drugs are clinically available at present due to the complex mechanism of Alzheimer’s disease. For the purpose of discovering potential anti-AD drugs in bisbenzylisoquinoline alkaloids, the anti-AD function and the mechanism of the function of berbamine hydrochloride (BBMH) were studied. Three kinds of AD model mice, double transgenic APP/PS1 AD mice, Gal-Alu AD mice induced by the intraperitoneal injection of d-galactose combined with the intragastric administration of aluminum trichloride, and Alu AD-like mice induced by stereotactic brain injection of aluminum trichloride, were administered with BBMH for 40 days at a dosage of 280 mg/kg/d. The effects of BBMH on the learning and memory behavior of the AD mice were studied through the Morris water maze experiment, and the influences of BBMH on the pathological features of AD, including the deposition of Aβ, the lesions of pyramidal cells (neurons), and the formation of neurofibrillary tangles, were studied by the immunohistochemical staining, hematoxylin-eosin staining, and silver staining of the brain tissues of the mice. The water maze experiment showed that BBMH could significantly improve the learning and memory abilities of three kinds of treated mice. Immunohistochemical staining showed that BBMH could significantly reduce the deposition of Aβ in the brain tissues of treated mice. Hematoxylin-eosin staining showed that BBMH could significantly alleviate the lesions of pyramidal cells in the hippocampal tissue of the mice. Silver staining showed that BBMH could significantly reduce the formation of neurofibrillary tangles in the hippocampal tissue of the mice. These results indicated that BBMH has significant anti-AD effects and the potential as an anti-AD drug. Western blot analysis of the brain tissue of the mice showed that the expression level of calpain, a Ca²⁺-dependent proteolytic enzyme, was significantly inhibited and the expression level of SelK, a selenoprotein mainly expressed in immune cells, was significantly increased. It is speculated that the anti-AD effect of BBMH is related to the improvement of the phagocytosis of microglial cells in brain tissues and macrophages migrated into the brain as well as the regulation of calcium homeostasis and calcium-dependent proteases in the brain tissues of the mice.

Antioxidants in Alzheimer's Disease: Current Therapeutic Significance and Future Prospects

Alzheimer's disease (AD) rate is accelerating with the increasing aging of the world's population. The World Health Organization (WHO) stated AD as a global health priority. According to the WHO report, around 82 million people in 2030 and 152 million in 2050 will develop dementia (AD contributes 60% to 70% of cases), considering the current scenario. AD is the most common neurodegenerative disease, intensifying impairments in cognition, behavior, and memory. Histopathological AD variations include extracellular senile plaques' formation, tangling of intracellular neurofibrils, and synaptic and neuronal loss in the brain. Multiple evidence directly indicates that oxidative stress participates in an early phase of AD before cytopathology. Moreover, oxidative stress is induced by almost all misfolded protein lumps like α-synuclein, amyloid-β, and others. Oxidative stress plays a crucial role in activating and causing various cell signaling pathways that result in lesion formations of toxic substances, which foster the development of the disease. Antioxidants are widely preferred to combat oxidative stress, and those derived from natural sources, which are often incorporated into dietary habits, can play an important role in delaying the onset as well as reducing the progression of AD. However, this approach has not been extensively explored yet. Moreover, there has been growing evidence that a combination of antioxidants in conjugation with a nutrient-rich diet might be more effective in tackling AD pathogenesis. Thus, considering the above-stated fact, this comprehensive review aims to elaborate the basics of AD and antioxidants, including the vitality of antioxidants in AD. Moreover, this review may help researchers to develop effectively and potentially improved antioxidant therapeutic strategies for this disease as it also deals with the clinical trials in the stated field.

In Vitro Methodologies to Study the Role of Advanced Glycation End Products (AGEs) in Neurodegeneration

Advanced glycation end products (AGEs) can be present in food or be endogenously produced in biological systems. Their formation has been associated with chronic neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis. The implication of AGEs in neurodegeneration is related to their ability to bind to AGE-specific receptors and the ability of their precursors to induce the so-called “dicarbonyl stress”, resulting in cross-linking and protein damage. However, the mode of action underlying their role in neurodegeneration remains unclear. While some research has been carried out in observational clinical studies, further in vitro studies may help elucidate these underlying modes of action. This review presents and discusses in vitro methodologies used in research on the potential role of AGEs in neuroinflammation and neurodegeneration. The overview reveals the main concepts linking AGEs to neurodegeneration, the current findings, and the available and advisable in vitro models to study their role. Moreover, the major questions regarding the role of AGEs in neurodegenerative diseases and the challenges and discrepancies in the research field are discussed.

Lycium barbarum extract promotes M2 polarization and reduces oligomeric amyloid-β-induced inflammatory reactions in microglial cells

Lycium barbarum (LB) is a traditional Chinese medicine that has been demonstrated to exhibit a wide variety of biological functions, such as antioxidation, neuroprotection, and immune modulation. One of the main mechanisms of Alzheimer's disease is that microglia activated by amyloid beta (Aβ) transform from the resting state to an M1 state and release pro-inflammatory cytokines to the surrounding environment. In the present study, immortalized microglial cells were pretreated with L. barbarum extract for 1 hour and then treated with oligomeric Aβ for 23 hours. The results showed that LB extract significantly increased the survival of oligomeric Aβ-induced microglial cells, downregulated the expression of M1 pro-inflammatory markers (inducible nitric oxide synthase, tumor necrosis factor α, interleukin-6, and interleukin-1β), and upregulated the expression of M2 anti-inflammatory markers (arginase-1, chitinase-like protein 3, and interleukin-4). LB extract also inhibited the oligomeric Aβ-induced secretion of tumor necrosis factor α, interleukin-6, and interleukin-1β in microglial cells. The results of in vitro cytological experiments suggest that, in microglial cells, LB extract can inhibit oligomeric Aβ-induced M1 polarization and concomitant inflammatory reactions, and promote M2 polarization.

Neuroprotective Natural Products for Alzheimer's Disease

Alzheimer's disease (AD) is the number one neurovegetative disease, but its treatment options are relatively few and ineffective. In efforts to discover new strategies for AD therapy, natural products have aroused interest in the research community and in the pharmaceutical industry for their neuroprotective activity, targeting different pathological mechanisms associated with AD. A wide variety of natural products from different origins have been evaluated preclinically and clinically for their neuroprotective mechanisms in preventing and attenuating the multifactorial pathologies of AD. This review mainly focuses on the possible neuroprotective mechanisms from natural products that may be beneficial in AD treatment and the natural product mixtures or extracts from different sources that have demonstrated neuroprotective activity in preclinical and/or clinical studies. It is believed that natural product mixtures or extracts containing multiple bioactive compounds that can work additively or synergistically to exhibit multiple neuroprotective mechanisms might be an effective approach in AD drug discovery.

Current Evidence on the Protective Effects of Recombinant Human Erythropoietin and Its Molecular Variants against Pathological Hallmarks of Alzheimer's Disease

Substantial evidence in the literature demonstrates the pleiotropic effects of the administration of recombinant human erythropoietin (rhEPO) and its molecular variants in different tissues and organs, including the brain. Some of these reports suggest that the chemical properties of this molecule by itself or in combination with other agents (e.g., growth factors) could provide the necessary pharmacological characteristics to be considered a potential protective agent in neurological disorders such as Alzheimer’s disease (AD). AD is a degenerative disorder of the brain, characterized by an aberrant accumulation of amyloid β (Aβ) and hyperphosphorylated tau (tau-p) proteins in the extracellular and intracellular space, respectively, leading to inflammation, oxidative stress, excitotoxicity, and other neuronal alterations that compromise cell viability, causing neurodegeneration in the hippocampus and the cerebral cortex. Unfortunately, to date, it lacks an effective therapeutic strategy for its treatment. Therefore, in this review, we analyze the evidence regarding the effects of exogenous EPOs (rhEPO and its molecular variants) in several in vivo and in vitro Aβ and tau-p models of AD-type neurodegeneration, to be considered as an alternative protective treatment to this condition. Particularly, we focus on analyzing the differential effect of molecular variants of rhEPO when changes in doses, route of administration, duration of treatment or application times, are evaluated for the improved cellular alterations generated in this disease. This narrative review shows the evidence of the effectiveness of the exogenous EPOs as potential therapeutic molecules, focused on the mechanisms that establish cellular damage and clinical manifestation in the AD.

Alzheimer's disease: natural products as inhibitors of neuroinflammation

Alzheimer’s disease (AD) is the most common form of dementia and affects 44 million people worldwide. New emerging evidence from pre-clinical and clinical investigations shows that neuroinflammation is a major pathological component of AD suggesting that anti-inflammatory strategies are important in delaying the onset or slowing the progression of the disease. However, efforts to employ current anti-inflammatory agents in AD clinical trials have produced limited success. Consequently, there is a need to explore anti-inflammatory natural products, which target neuroinflammatory pathways relevant to AD pathogenesis. This review summarises important druggable molecular targets of neuroinflammation and presents classes of anti-neuroinflammatory natural products with potentials for preventing and reducing symptoms of AD.

Tetrandrine Attenuated Doxorubicin-Induced Acute Cardiac Injury in Mice

Oxidative damage is closely involved in the development of doxorubicin- (DOX-) induced cardiotoxicity. It has been reported that tetrandrine can prevent the development of cardiac hypertrophy by suppressing reactive oxygen species- (ROS-) dependent signaling pathways in mice. However, whether tetrandrine could attenuate DOX-related cardiotoxicity remains unclear. To explore the protective effect of tetrandrine, mice were orally given a dose of tetrandrine (50 mg/kg) for 4 days beginning one day before DOX injection. To induce acute cardiac injury, the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg). The data in our study showed that tetrandrine prevented DOX-related whole-body wasting and heart atrophy, decreased markers of cardiac injury, and improved cardiac function in mice. Moreover, tetrandrine supplementation protected the mice against oxidative damage and myocardial apoptotic death. Tetrandrine supplementation also reduced ROS production and improved cell viability after DOX exposure in vitro. We also found that tetrandrine supplementation increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression and activity in vivo and in vitro. The protection of tetrandrine supplementation was blocked by Nrf2 deficiency in mice. In conclusion, our study found that tetrandrine could improve cardiac function and prevent the development of DOX-related cardiac injury through activation of Nrf2.

Non-polyphenolic natural inhibitors of amyloid aggregation

Protein misfolding diseases (PMDs) are chronic and progressive, with no effective therapy so far. Aggregation and misfolding of amyloidogenic proteins are closely associated with the onset and progression of PMDs, such as amyloid-β (Aβ) in Alzheimer's disease, α-Synuclein (α-Syn) in Parkinson's disease and human islet amyloid polypeptide (hIAPP) in type 2 diabetes. Inhibiting toxic aggregation of amyloidogenic proteins is regarded as a promising therapeutic approach in PMDs. The past decade has witnessed the rapid progresses of this field, dozens of inhibitors have been screened and verified in vitro and in vivo, demonstrating inhibitory effects against the aggregation and misfolding of amyloidogenic proteins, together with beneficial effects. Natural products are major sources of small molecule amyloid inhibitors, a number of natural derived compounds have been identified with great bioactivities and translational prospects. Here, we review the non-polyphenolic natural inhibitors that potentially applicable for PMDs treatment, along with their working mechanisms. Future directions are proposed for the development and clinical applications of these inhibitors.

Radix Stephaniae Tetrandrine: An Emerging Role for Management of Breast Cancer

Background:

Radix Stephaniae Tetrandrine (RST), known as FangJi (Pinyin name) in Chinese, is the dried root of Stephania tetrandra S.Moore, and has been prescribed in combination with other herbs to treat cardiovascular diseases and breast cancer in traditional Chinese medicine (TCM) clinical trials.

Objective:

The aim of the review is to provide a comprehensive evaluation about the application of RST in breast cancer management in TCM clinical trials, its ingredients, and its action on preventing the development of breast cancer in vitro and in vivo studies.

Methods:

Literature sources used were Pubmed, CNKI.net, Cqvip.com, and the Web of Science. For the inquiry, keywords such as Fangji, breast cancer, clinical trials, Radix Stephaniae Tetrandrine, tetrandrine, and fangchinoline were used in various combinations. About 150 research papers and reviews were consulted.

Results:

In TCM, RST exhibited the anti-tumor ability through its action on the bladder and lungs through dispersing phlegm and blood stasis. 10 clinical trials were identified which used RST in combination with other herbs to treat breast cancer. On average, the trials were characterized by high efficacy (>85%) and low toxicity. However, most of the clinical trials are characterized as small patient samples, poor design, and different combinations of herbs in prescriptions. To date, more and more compounds have been isolated from this plant. RST exhibited anti-tumor activities by targeting reversing multidrug resistance, inhibiting cell proliferation, inducing apoptosis, preventing tumor angiogenesis, anti-oxidation, anti-inflammation, and enhancing the sensitization and attenuating the toxicity of radiotherapy.

Conclusion:

The successful applications of RST in TCM clinical trials and preclinical experiments to beating breast cancer will provide potent lead compounds in the identification of novel anti-cancer drugs, which further contributes to the scientific exploration of functions of RST in TCM.

Indirubin-3'-monoxime prevents aberrant activation of GSK-3β/NF-κB and alleviates high fat-high fructose induced Aβ-aggregation, gliosis and apoptosis in mice brain

Deciphering the molecular mechanisms of amyloid pathology and glial cell-mediated neuroinflammation, offers a novel avenue for therapeutic intervention against neurodegeneration. Recent findings demonstrate a crucial link between activation of glycogen synthase kinase-3β (GSK-3β), amyloid deposition and a neuroinflammatory state. However, studies demonstrating the pharmacological effects of GSK-3β inhibition and the interlinked molecular mechanisms still remain elusive. The present study explores whether high fat-high fructose diet (HFFD)-induced neuropathological changes could be alleviated by indirubin-3'-monoxime (IMX), a GSK-3β inhibitor. Male Swiss albino mice (8 weeks old) were fed with normal pellet or HFFD for 60 days. HFFD mice were treated with IMX once daily for last 7 days of the experimental period. HFFD fed-mice had significant amyloid deposits in cerebral cortex and hippocampus, and protein expression analyses showed activation of GSK-3β, nuclear translocation of NF-κB p65 and upregulation of inflammatory (TNF-α, IL-6, COX-2), astrocytic (GFAP), glial surface (CD-68) and pro-apoptotic markers (Bax and caspase-3). IMX treatment promotes the inhibitory phosphorylation of GSK-3β at Ser⁹ and moreover, a marked reduction in the phosphorylation of IKK-β, which prevents translocation and activation of NF-κB. Protein expression studies in IMX-treated brain tissues positively correlate with the anti-neuroinflammatory effects of GSK-3β inhibition. Taken together, our results provide substantial evidence that IMX could potentially attenuate neuroinflammation in coordination with the master transcription factor-NF-κB.

Tetrandrine suppresses cervical cancer growth by inducing apoptosis in vitro and in vivo

Introduction and aim

Cervical cancers are the most common forms of cancer that occur in women globally and are difficult to be cured in their terminal stages. Tetrandrine (TET), a monomeric compound isolated from a traditional Chinese medicine, Radix Stephania tetrandrae, exhibits anticancer effects on different tumor types. However, the mechanisms by which TET regulates the proliferation, apoptosis, migration, and invasion in cervical cancer remain unclear. Thus, this study aimed to investigate the therapeutic effects of TET on cervical cancer in vitro and in vivo.

Methods

Cell Counting Kit-8, immunofluorescence, flow cytometry, wound healing, and transwell migration assays were used to detect cell proliferation, apoptosis, and migration and invasion, respectively, in vitro. In addition, immunohistochemical assays were performed to evaluate tumor growth and apoptosis in vivo. Moreover, Western blotting was used to examine active caspase 3, matrix metalloproteinase (MMP)2, and MMP9 protein levels in vitro and in vivo.

Results

The results revealed that TET significantly inhibited SiHa cell proliferation in vitro and suppressed tumor growth in vivo. Meanwhile, TET was revealed to induce cervical cancer cell apoptosis by upregulating active caspase 3 in vitro and in vivo. Furthermore, the migration and invasion of SiHa cells were inhibited by TET accompanied with MMP2 and MMP9 downregulation.

Conclusion

We have shown that TET inhibited cervical tumor growth and migration in vitro and in vivo for the first time. The accumulating evidence suggests that TET could be a potential therapeutic agent for the treatment of cervical cancer.

Molecular Mechanisms Involved in Oxidative Stress-Associated Liver Injury Induced by Chinese Herbal Medicine: An Experimental Evidence-Based Literature Review and Network Pharmacology Study

Oxidative stress, defined as a disequilibrium between pro-oxidants and antioxidants, can result in histopathological lesions with a broad spectrum, ranging from asymptomatic hepatitis to hepatocellular carcinoma in an orchestrated manner. Although cells are equipped with sophisticated strategies to maintain the redox biology under normal conditions, the abundance of redox-sensitive xenobiotics, such as medicinal ingredients originated from herbs or animals, can dramatically invoke oxidative stress. Growing evidence has documented that the hepatotoxicity can be triggered by traditional Chinese medicine (TCM) during treating various diseases. Meanwhile, TCM-dependent hepatic disorder represents a strong correlation with oxidative stress, especially the persistent accumulation of intracellular reactive oxygen species. Of note, since TCM-derived compounds with their modulated targets are greatly diversified among themselves, it is complicated to elaborate the potential pathological mechanism. In this regard, data mining approaches, including network pharmacology and bioinformatics enrichment analysis have been utilized to scientifically disclose the underlying pathogenesis. Herein, top 10 principal TCM-modulated targets for oxidative hepatotoxicity including superoxide dismutases (SOD), malondialdehyde (MDA), glutathione (GSH), reactive oxygen species (ROS), glutathione peroxidase (GPx), Bax, caspase-3, Bcl-2, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and nitric oxide (NO) have been identified. Furthermore, hepatic metabolic dysregulation may be the predominant pathological mechanism involved in TCM-induced hepatotoxic impairment.

Inhibition of histone deacetylase 1 or 2 reduces induced cytokine expression in microglia through a protein synthesis independent mechanism

Histone deacetylase (HDAC) inhibitors prevent neural cell death in in vivo models of cerebral ischaemia, brain injury and neurodegenerative disease. One mechanism by which HDAC inhibitors may do this is by suppressing the excessive inflammatory response of chronically activated microglia. However, the molecular mechanisms underlying this anti-inflammatory effect and the specific HDAC responsible are not fully understood. Recent data from in vivo rodent studies have shown that inhibition of class I HDACs suppresses neuroinflammation and is neuroprotective. In our study, we have identified that selective HDAC inhibition with inhibitors apicidin, MS-275 or MI-192, or specific knockdown of HDAC1 or 2 using siRNA, suppresses the expression of cytokines interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) in BV-2 murine microglia activated with lipopolysaccharide (LPS). Furthermore, we found that in the absence of HDAC1, HDAC2 is up-regulated and these increased levels are compensatory, suggesting that these two HDACs have redundancy in regulating the inflammatory response of microglia. Investigating the possible underlying anti-inflammatory mechanisms suggests an increase in protein expression is not important. Taken together, this study supports the idea that inhibitors selective towards HDAC1 or HDAC2, may be therapeutically useful for targeting neuroinflammation in brain injuries and neurodegenerative disease.

Original article. Patterns of microglial innate immune responses elicited by amyloid β1–42 and lipopolysaccharide: the similarities of the differences

Background: As part of their innate immune response to changes in the central nervous system environment, normally quiescent microglia become activated and increase expression of pattern recognition receptors, scavenger receptors, and production of inflammatory cytokines, proteinases, reactive oxygen species (ROS), and free radicals. These molecules have been implicated in the pathogenesis and progression of several neurodegenerative disorders including Alzheimer disease (AD).

Objective: We compared patterns of microglial innate immune responses elicited by nonfibrillar amyloid β peptide (nfAβ1-42) to those elicited by lipopolysaccharide (LPS).

Methods: Murine BV-2 microglial cells were exposed to either nfAβ1-42 or LPS for 12 h. Then, total RNA from each condition was isolated and expression levels of Toll-like receptor (TLR)-4, scavenger receptor class A (SRMARCO) and class B (SR-BI), CD36, and matrix metalloproteinase (MMP)-9 were determined by reverse transcription-quantitative real-time polymerase chain reaction. The amount of hydrogen peroxide (H2O2) and nitric oxide (NO) in the cell-free supernatant at 24 h were determined using 10-acetyl-3,7-dihydroxyphenoxazine (Amplex Red) and Griess reagent, respectively.

Results: nfAβ1-42 and LPS significantly increased expression of TLR-4, SR-MARCO, CD36, and MMP-9 and production of H2O2 and NO in BV-2 microglial cells compared with that of unstimulated cells. However, expression of SR-BI was significantly induced only when the cells were exposed to nfAβ1-42.

Conclusion: These findings indicate that pattern of microglial innate immune responses elicited by nfAβ1-42 overlap with that elicited by LPS and suggest a specific role of microglial SR-BI expression in AD pathogenesis.

Inhibitory effects of three bisbenzylisoquinoline alkaloids on lipopolysaccharide-induced microglial activation

Three bisbenzylisoquinoline alkaloids (liensinine, neferine, and isoliensinine) inhibit lipopolysaccharide-induced microglial activation.

Tetrandrine suppresses β‑glucan‑induced macrophage activation via inhibiting NF‑κB, ERK and STAT3 signaling pathways

Macrophages are important in inflammation through the production of various proinflammatory mediators. β‑glucan is a polymer of glucose, which is produced by numerous different organisms, including fungi, and acts as a trigger for the induction of inflammatory responses. Tetrandrine (TET), a bis‑benzylisoquinoline alkaloid isolated from the Chinese herb Radix Stephania tetrandra, has been demonstrated to modulate inflammatory responses. In the present study, it was investigated whether TET affects the inflammatory reaction induced by β‑glucan in murine and human macrophages. It was demonstrated that β‑glucan induced the activation of nuclear factor (NF)‑κB and markedly increased the levels of tumor necrosis factor‑α (TNF‑α) and interleukin 1 β (IL‑1β) in macrophages. Treatment with TET resulted in downregulation of phosphorylated NF‑κB p65 and reduction of the production of TNF‑α and IL‑1β. In addition, the phosphorylation of ERK and STAT3 was decreased by TET in activated macrophages. Furthermore, it was demonstrated that the inhibitory effects of TET on β‑glucan‑induced macrophage activation was not due to its cytotoxic action. Conclusively, these results indicate that TET can decrease the inflammatory responses mediated by β‑glucan in macrophages. Thus, TET may serve as an effective tool for the treatment of β‑glucan‑associated inflammatory diseases.

Neuroprotective effect of loganin against Aβ25-35-induced injury via the NF-κB-dependent signaling pathway in PC12 cells

Amyloid-beta (Aβ) protein, the main constituent of senile plaques, is believed to play a pivotal role in the pathogenesis of Alzheimer's disease (AD). AD is closely associated with inflammatory reactions which are considered to be responses to Aβ deposition. The present study investigated the effect of loganin on Aβ25-35-induced inflammatory damage and the underlying molecular mechanism of its neuroprotective action. Loganin predominantly prevented Aβ25-35-stimulated cell death through suppressing ROS generation, and attenuating apoptosis by inhibiting caspase-3 activity and regulating cell cycle. Furthermore, loganin suppressed the level of TNF-α and protein expression of iNOS and COX-2 in Aβ25-35-injured PC12 cells. These inhibitions appeared to correlate with the suppression of NF-κB activation by loganin, as pre-treating cells with loganin blocked the translocation of NF-κB into the nuclear compartment and degradation of the inhibitory subunit IκB. Loganin substantially inhibited phosphorylation of MAPKs including ERK1/2, p38 and JNK, which are closely related to regulation of NF-κB activation. Taken together, the results implied that loganin attenuated neuroinflammatory responses through the inactivation of NF-κB by NF-κB dependent inflammatory pathways and phosphorylation of MAPK in Aβ25-35-induced PC12 cells.

Low-Dose Homocystine Enhances Proliferation and Migration of Bv2 Microglia Cells

Homocysteine (Hcy) is a non-essential amino acid that is derived from the breakdown of dietary methionine. Hyperhomocysteinemia (HHcy) is an independent risk factor for a variety of chronic diseases, especially neurodegenerative conditions. To better understand the role of HHcy in the pathogenesis of neurodegenerative disorders, we investigated the effect of Hcy on the proliferation and activation of microglia Bv2 cells. Cells were treated with six different Hcy concentrations: 0, 50, 100, 300, 500, and 1000 µM for different time periods (8, 12, 16, 24, and 48 h). The morphology of Bv2 cells was observed, and cell activity and proliferation were detected. Cell migration and secretion of pro-inflammatory cytokines were detected by the scratch wound assay, the transwell assay, and ELISA, respectively. The effect of Hcy on Bv2 proliferation occurred earlier (<24 h, especially 16 h) after treatment with concentrations between 100 and 300 μM, and there was no cytotoxicity to Bv2 cells. Meanwhile, functional assays suggested that Hcy not only promoted Bv2 secretion of the pro-inflammatory cytokines IL-1β, TNF-α, and IL-6, but also enhanced Bv2 migration and invasion, with 100 μM being the most effective concentration. In summary, Bv2 proliferation and activation can be promoted by short-term treatment with low-dose Hcy.

Protective Effect of Tetrandrine on Sodium Taurocholate-Induced Severe Acute Pancreatitis

Tet is a type of alkaloid extracted from Stephania tetrandra, and it has recently been demonstrated that Tet can protect against inflammation and free radical injury and inhibit the release of inflammatory mediators. The present study was designed to observe the protective effect of Tet on sodium taurocholate-induced severe acute pancreatitis (SAP). The rat model of SAP was induced by retrograde bile duct injection of sodium taurocholate and then treated with Verapamil and Tet. The results showed that Tet can reduce NF-κB activation in pancreas issue, inhibit the SAP cascade, and improve SAP through inducing pancreas acinar cell apoptosis and stabilizing intracellular calcium in the pancreas, thus mitigating the damage to the pancreas. Our study revealed that Tet may reduce systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndromes (MODS) to protect against damage, and these roles may be mediated through the NF-κB pathway to improve the proinflammatory/anti-inflammatory imbalance.

Lipoic acid and pentoxifylline mitigate nandrolone decanoate-induced neurobehavioral perturbations in rats via re-balance of brain neurotransmitters, up-regulation of Nrf2/HO-1 pathway, and down-regulation of TNFR1 expression

Behavioral perturbations associated with nandrolone decanoate abuse by athletes and adolescents may be attributed to oxidative stress and inflammation. However, the underlying mechanisms are not yet fully explored. On the other hand, the natural antioxidant lipoic acid can pass the blood brain barrier and enhance Nrf2/HO-1 (nuclear factor erythroid-2 related factor 2/heme oxygenase-1) pathway. In addition, the phosphodiesterase-IV inhibitor xanthine derivative pentoxifylline has a remarkable inhibitory effect on tumor necrosis factor-alpha (TNF-α). Therefore, this study aimed at investigation of the possible protective effects of lipoic acid and/or pentoxifylline against nandrolone-induced neurobehavioral alterations in rats. Accordingly, male albino rats were randomly distributed into seven groups and treated with either vehicle, nandrolone (15mg/kg, every third day, s.c.), lipoic acid (100mg/kg/day, p.o.), pentoxifylline (200mg/kg/day, i.p.), or nandrolone with lipoic acid and/or pentoxifylline. Rats were challenged in the open field, rewarded T-maze, Morris water maze, and resident-intruder aggression behavioral tests. The present findings showed that nandrolone induced hyperlocomotion, anxiety, memory impairment, and aggression in rats. These behavioral abnormalities were accompanied by several biochemical changes, including altered levels of brain monoamines, GABA, and acetylcholine, enhanced levels of malondialdehyde and TNF-α, elevated activity of acetylcholinesterase, and up-regulated expression of TNF-α receptor-1 (TNFR1). In addition, inhibited catalase activity, down-regulated Nrf2/HO-1 pathway, and suppressed acetylcholine receptor expression were observed. Lipoic acid and pentoxifylline combination significantly mitigated all the previously mentioned deleterious effects mainly via up-regulation of Nrf2/HO-1 pathway, inhibition of TNF-α and down-regulation of TNFR1 expression. In conclusion, the biochemical and histopathological findings of this study revealed the protective mechanisms of lipoic acid and pentoxifylline against nandrolone-induced behavioral changes and neurotoxicity in rats.

Trimethyltin-Induced Microglial Activation via NADPH Oxidase and MAPKs Pathway in BV-2 Microglial Cells

Trimethyltin (TMT) is known as a potent neurotoxicant that causes neuronal cell death and neuroinflammation, particularly in the hippocampus. Microglial activation is one of the prominent pathological features of TMT neurotoxicity. Nevertheless, it remains unclear how microglial activation occurs in TMT intoxication. In this study, we aimed to investigate the signaling pathways in TMT-induced microglial activation using BV-2 murine microglial cells. Our results revealed that TMT generates reactive oxygen species (ROS) and increases the expression of CD11b and nuclear factor-κB- (NF-κB-) mediated nitric oxide (NO) and tumor necrosis factor- (TNF-) α in BV-2 cells. We also observed that NF-κB activation was controlled by p38 and JNK phosphorylation. Moreover, TMT-induced ROS generation occurred via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in BV-2 cells. Interestingly, treatment with the NADPH oxidase inhibitor apocynin significantly suppressed p38 and JNK phosphorylation and NF-κB activation and ultimately the production of proinflammatory mediators upon TMT exposure. These findings indicate that NADPH oxidase-dependent ROS generation activated p38 and JNK mitogen-activated protein kinases (MAPKs), which then stimulated NF-κB to release proinflammatory mediators in the TMT-treated BV-2 cells.

Anti-nociceptive, anti-inflammatory and toxicological evaluation of Fang-Ji-Huang-Qi-Tang in rodents

BACKGROUND

Fang-Ji-Huang-Qi-Tang (abbreviated as FJHQT), composed by six medicinal herbs including Radix Stephania Tetrandra, Radix Astragali, Rhizoma Atractylodis Macrocephalae, Radix Glycyrrhizae, Rhizoma Zingiberis and Fructus Ziziphi Jujubae, is a frequently Chinese prescription for treating painful and inflammatory disorders such as rheumatoid arthritis. When Radix Stephania Tetrandra was misused with Aristolochia species, acute or chronic nephropathy caused by aristolochic acid was happened. Thus, the present study was aimed to identify Radix Stephania Tetrandra and performed the pharmacological and toxicological evaluation of FJHQT extract in rodents.

METHODS

Radix Stephania Tetrandra was identified by macroscopic and microscopic observation, and the content of tetrandrine in FJHQT extract was measured by high performance liquid chromatography. Then, the pharmacological activities of FJHQT extract with respect to clinical use was investigated with acetic acid-induced writhing response, formalin-induced licking response and carrageenan-induced paw edema. Finally, we evaluated the subacute toxicology of FJHQT extract after 28-day repeated oral administration in rats.

RESULTS

Radix Stephania Tetrandra was correctly used in FJHQT extract, and the content of tetrandrine in FJHQT extract was 2.5 mg/g. FJHQT extract produced a pronounced and dose-dependent antinociceptive and anti-inflammatory effects in three above models. FJHQT extract after 28-day repeated administration did not caused any hematological, biochemical and histological change in rats.

CONCLUSIONS

We suggest that FJHQT extract is a high safety index Chinese medicine for antinociceptive and anti-inflammatory application when Radix Stephania Tetrandra was correctly used in FJHQT. Its antinociceptive and anti-inflammatory mechanism might be related to peripheral nociceptive pathway such as prostaglandins.

Tetrandrine suppresses lipopolysaccharide-induced microglial activation by inhibiting NF-κB and ERK signaling pathways in BV2 cells

Background and Objective

Tetrandrine (TET) is a bisbenzylisoquinoline alkaloid extracted from Stephania tetrandra Moore. Recent studies have suggested that TET can reduce the inflammatory response in microglia, but the mechanisms remain unclear. The aim of this study is to investigate whether TET can inhibit lipopolysaccharide (LPS)-induced microglial activation and clarify its possible mechanisms.

Study Design/Materials and Methods

Cell viability assays and cell apoptosis assays were used to determine the working concentrations of TET. Then, BV2 cells were seeded and pretreated with TET for 2 h. LPS was then added and incubated for an additional 24 hours. qRT-PCR and ELISA were used to measure the mRNA or protein levels of IL1β and TNFα. Western blotting was utilized to quantify the expression of CD11b and cell signaling proteins.

Results

TET at optimal concentrations (0.1 µM, 0.5 µM or 1 µM) did not affect the cell viability. After TET pretreatment, the levels of IL1β and TNFα (both in transcription and translation) were significantly inhibited in a dose-dependent manner. Further studies indicated that phospho-p65, phospho-IKK, and phospho-ERK 1/2 expression were also suppressed by TET.

Conclusions

Our results indicate that TET can effectively suppress microglial activation and inhibit the production of IL1β and TNFα by regulating the NF-kB and ERK signaling pathways. Together with our previous studies, we suggest that TET would be a promising candidate to effectively suppress overactivated microglia and alleviate neurodegeneration in glaucoma.

Warifteine, an alkaloid purified from Cissampelos sympodialis, inhibits neutrophil migration in vitro and in vivo

Cissampelos sympodialis Eichl is a plant from the Northeast and Southeast of Brazil. Its root infusion is popularly used for treatment of inflammatory and allergic diseases. We investigated whether warifteine, its main alkaloid, would have anti-inflammatory effect due to a blockage of neutrophil function. In vivo warifteine treatment inhibited casein-induced neutrophil migration to the peritoneal cavity but did not inhibit neutrophil mobilization from the bone marrow. Analysis of the direct effect of warifteine upon neutrophil adherence and migration in vitro demonstrated that the alkaloid decreased cell adhesion to P and E-selectin-transfected cells. In addition, fLMP-induced neutrophil migration in a transwell system was blocked by warifteine; this effect was mimicked by cAMP mimetic/inducing substances, and warifteine increased intracellular cAMP levels in neutrophils. The production of DNA extracellular traps (NETs) was also blocked by warifteine but there was no alteration on PMA-induced oxidative burst or LPS-stimulated TNFα secretion. Taken together, our data indicate that the alkaloid warifteine is a potent anti-inflammatory substance and that it has an effect on neutrophil migration through a decrease in both cell adhesion and migration.

Tetrandrine protects mouse retinal ganglion cells from ischemic injury

This study aimed to determine the protective effects of tetrandrine (Tet) on murine ischemia-injured retinal ganglion cells (RGCs). For this, we used serum deprivation cell model, glutamate and hydrogen peroxide (H₂O₂)-induced RGC-5 cell death models, and staurosporine-differentiated neuron-like RGC-5 in vitro. We also investigated cell survival of purified primary-cultured RGCs treated with Tet. An in vivo retinal ischemia/reperfusion model was used to examine RGC survival after Tet administration 1 day before ischemia. We found that Tet affected RGC-5 survival in a dose- and time-dependent manner. Compared to dimethyl sulfoxide treatment, Tet increased the numbers of RGC-5 cells by 30% at 72 hours. After 48 hours, Tet protected staurosporine-induced RGC-5 cells from serum deprivation-induced cell death and significantly increased the relative number of cells cultured with 1 mM H₂O₂ (P<0.01). Several concentrations of Tet significantly prevented 25-mM-glutamate-induced cell death in a dose-dependent manner. Tet also increased primary RGC survival after 72 and 96 hours. Tet administration (10 μM, 2 μL) 1 day before retinal ischemia showed RGC layer loss (greater survival), which was less than those in groups with phosphate-buffered saline intravitreal injection plus ischemia in the central (P=0.005, n=6), middle (P=0.018, n=6), and peripheral (P=0.017, n=6) parts of the retina. Thus, Tet conferred protective effects on serum deprivation models of staurosporine-differentiated neuron-like RGC-5 cells and primary cultured murine RGCs. Furthermore, Tet showed greater in vivo protective effects on RGCs 1 day after ischemia. Tet and ciliary neurotrophic factor maintained the mitochondrial transmembrane potential (ΔΨm) of primary cultured RGCs and inhibited the expression of activated caspase-3 and bcl-2 in ischemia/reperfusion-insult retinas.

ROS generated by CYP450, especially CYP2E1, mediate mitochondrial dysfunction induced by tetrandrine in rat hepatocytes

AIM

Tetrandrine, an alkaloid with a remarkable pharmacological profile, induces oxidative stress and mitochondrial dysfunction in hepatocytes; however, mitochondria are not the direct target of tetrandrine, which prompts us to elucidate the role of oxidative stress in tetrandrine-induced mitochondrial dysfunction and the sources of oxidative stress.

METHODS

Rat primary hepatocytes were isolated by two-step collagenase perfusion. Mitochondrial function was evaluated by analyzing ATP content, mitochondrial membrane potential (MMP) and the mitochondrial permeability transition. The oxidative stress was evaluated by examining changes in the levels of reactive oxygen species (ROS) and glutathione (GSH).

RESULTS

ROS scavengers largely attenuated the cytotoxicity induced by tetrandrine in rat hepatocytes, indicating the important role of ROS in the hepatotoxicity of tetrandrine. Of the multiple ROS inhibitors that were tested, only inhibitors of CYP450 (SKF-525A and others) reduced the ROS levels and ameliorated the depletion of GSH. Mitochondrial function assays showed that the mitochondrial permeability transition (MPT) induced by tetrandrine was inhibited by SKF-525A and vitamin C (VC), both of which also rescued the depletion of ATP levels and the mitochondrial membrane potential. Upon inhibiting specific CYP450 isoforms, we observed that the inhibitors of CYP2D, CYP2C, and CYP2E1 attenuated the ATP depletion that occurred following tetrandrine exposure, whereas the inhibitors of CYP2D and CYP2E1 reduced the ROS induced by tetrandrine. Overexpression of CYP2E1 enhanced the tetrandrine-induced cytotoxicity.

CONCLUSION

We demonstrated that CYP450 plays an important role in the mitochondrial dysfunction induced by the administration of tetrandrine. ROS generated by CYP450, especially CYP2E1, may contribute to the mitochondrial dysfunction induced by tetrandrine.

Inhibition of microglia activation as a phenotypic assay in early drug discovery

Complex biological processes such as inflammation, cell death, migration, proliferation, and the release of biologically active molecules can be used as outcomes in phenotypic assays during early stages of drug discovery. Although target-based approaches have been widely used over the past decades, a disproportionate number of first-in-class drugs have been identified using phenotypic screening. This review details phenotypic assays based on inhibition of microglial activation and their utility in primary and secondary screening, target validation, and pathway elucidation. The role of microglia, both in normal as well as in pathological conditions such as chronic neurodegenerative diseases, is reviewed. Methodologies to assess microglia activation in vitro are discussed in detail, and classes of therapeutic drugs known to decrease the proinflammatory and cytotoxic responses of activated microglia are appraised, including inhibitors of glutaminase, cystine/glutamate antiporter, nuclear factor κB, and mitogen-activated protein kinases.

IL-33 is induced by amyloid-β stimulation and regulates inflammatory cytokine production in retinal pigment epithelium cells

Age-related macular degeneration (AMD) is the predominant cause of irreversible blindness in the elderly population. Despite intensive basic and clinical research, its pathogenesis remains unclear. However, evidence suggests that immunological and inflammatory factors contribute to the pathogenesis of AMD. A newly identified cytokine, IL-33, appears to be an important pro-inflammatory cytokine promoting tissue inflammation. In this study, IL-33 was increased through amyloid-beta(1-40) (Aβ(1-40)) stimulation and regulated inflammatory cytokines including IL-6, IL-8, IL-1β, and TNF-α secretion using different signaling pathways in retinal pigment epithelium (RPE) cells. Furthermore, ST2L, the important component of the IL-33 receptor, was significantly increased following recombinant human IL-33 stimulation in RPE cells. These findings suggest that IL-33-mediated inflammatory responses in RPE cells are involved in the pathogenesis of AMD. Greater understanding of the inflammatory effect of IL-33 and its role in RPE cells should aid the development of future clinical therapeutics and enable novel pharmacological approaches towards the prevention of AMD.

A comparative review of cell culture systems for the study of microglial biology in Alzheimer's disease

Over the past two decades, it has become increasingly apparent that Alzheimer’s disease neuropathology is characterized by activated microglia (brain resident macrophages) as well as the classic features of amyloid plaques and neurofibrillary tangles. The intricacy of microglial biology has also become apparent, leading to a heightened research interest in this particular cell type. Over the years a number of different microglial cell culturing techniques have been developed to study either primary mammalian microglia, or immortalized cell lines. Each microglial system has advantages and disadvantages and should be selected for its appropriateness in a particular research context. This review summarizes several of the most common microglial cell culture systems currently being employed in Alzheimer’s research including primary microglia; BV2 and N9 retroviral immortalized microglia; human immortalized microglia (HMO6); and spontaneously immortalized rodent microglial lines (EOC lines and HAPI cells). Particularities of cell culture requirements and characteristics of microglial behavior, especially in response to applied inflammogen stimuli, are compared and discussed across these cell types.