Anti-neuroinflammatory activity of Kamebakaurin from Isodon japonicus via inhibition of c-Jun NH₂-terminal kinase and p38 mitogen-activated protein kinase pathway in activated microglial cells

Kamebakaurin Suppresses Antigen-Induced Mast Cell Activation by Inhibition of FcεRI Signaling Pathway

INTRODUCTION

Kamebakaurin is an active constituent of both Rabdosia japonica and Rabdosia excisa, which are utilized in Chinese traditional medicine for improving symptoms in patients with allergies. We investigated the molecular mechanisms of the anti-allergic effects of kamebakaurin using BMMCs.

METHODS

The degranulation ratio, histamine release, and the interleukin (IL)-4, leukotriene B4 (LTB4), and cysteinyl leukotriene productions on antigen-triggered BMMC were investigated. Additionally, the effects of kamebakaurin on signal transduction proteins were examined by Western blot and binding to the Syk and Lyn kinase domain was calculated. The effects of kamebakaurin on antigen-induced hyperpermeability were investigated using mouse model.

RESULTS

At 10 μm, kamebakaurin partially inhibited degranulation, histamine release, and IL-4 production. At 30 μm, kamebakaurin partially reduced LTB4 and cysteinyl leukotriene productions and suppressed degranulation, histamine release, and IL-4 production. Phosphorylation of both Syk Y519/520 and its downstream protein, Gab2, was reduced by kamebakaurin, and complete inhibition was observed with 30 μm kamebakaurin. In contrast, phosphorylation of Erk was only partially inhibited, even in the presence of 30 μm kamebakaurin. Syk Y519/520 is known to be auto-phosphorylated via intramolecular ATP present in its own ATP-binding site, and this auto-phosphorylation triggers degranulation, histamine release, and IL-4 production. Docking simulation study indicated kamebakaurin blocked ATP binding to the ATP-binding site in Syk. Therefore, inhibition of Syk auto-phosphorylation by kamebakaurin binding to the Syk ATP-binding site appeared to cause a reduction of histamine release and IL-4 production. Kamebakaurin inhibited antigen-induced vascular hyperpermeability in a dose-dependent fashion but did not reduce histamine-induced vascular hyperpermeability.

CONCLUSION

Kamebakaurin ameliorates allergic symptoms via inhibition of Syk phosphorylation; thus, kamebakaurin could be a lead compound for the new anti-allergic drug.

Ethnobotanical, Phytochemical, and Pharmacological Properties of the Subfamily Nepetoideae (Lamiaceae) in Inflammatory Diseases

Nepetoideae is the most diverse subfamily of Lamiaceae, and some species are well known for their culinary and medicinal uses. In recent years, there has been growing interest in the therapeutic properties of the species of this group regarding inflammatory illnesses. This study aims to collect information on traditional uses through ethnobotanical, pharmacological, and phytochemical information of the subfamily Nepetoideae related to inflammatory diseases. UNAM electronic resources were used to obtain the information. The analysis of the most relevant literature was compiled and organised in tables. From this, about 106 species of the subfamily are traditionally recognised to alleviate chronic pain associated with inflammation. Pharmacological studies have been carried out in vitro and in vivo on approximately 308 species belonging to the genera Salvia, Ocimum, Thymus, Mentha, Origanum, Lavandula, and Melissa. Phytochemical and pharmacological evaluations have been performed and mostly prepared as essential oil or high polarity extracts, whose secondary metabolites are mainly of a phenolic nature. Other interesting and explored metabolites are diterpenes from the abietane, clerodane, and kaurane type; however, they have only been described in some species of the genera Salvia and Isodon. This review reveals that the Nepetoideae subfamily is an important source for therapeutics of the inflammatory process.

Isolation, Structure Determination, and Semisynthesis of Diphenazine Compounds from a Deep-Sea-Derived Strain of the Fungus Cystobasidium laryngis and Their Biological Activities

Phenazostatins E-J (1-6), six new diphenazine derivatives, were isolated from the EtOAc extract of the culture broth of a strain of Cystobasidium laryngis derived from deep-sea sediments of the Indian Ocean Ridge. The structures of 1-6 were elucidated based on the HRESIMS and 1D and 2D NMR spectra. The absolute configurations of 1-6, except for 3 and 6, were determined by modified Mosher's method, ECD data analysis, and calculations of optical rotation values. The absolute configurations of 3 and 6 were identified by chemical derivatization and comparing the specific rotation values with those of semisynthetic 3 obtained by the oxidation of 1 and saphenic acid (7). Phenazostatin J (6) was semisynthesized using saphenic acid (7) to prepare additional material for biological testing. During the purification of semisynthetic 6, a side product 9 was obtained from the reaction mixture along with 6. Compounds 1-6, along with previously reported 7 and 8, were assessed for anti-neuroinflammatory activity in LPS-induced BV-2 microglia cells. Compound 6 exhibited the highest anti-neuroinflammatory effect with an IC₅₀ value of 0.30 μM, but it showed cytotoxicity at higher concentrations than 1.0 μM. Accordingly, cytotoxicities of 1-9 were evaluated against six human cancer cell lines. Among tested compounds, 6 and 9 showed potent cytotoxicity (IC₅₀ values: 7.7-72 nM). Especially, 6 exhibited the strongest cytotoxicity with an IC₅₀ value of 7.7 nM against the NUGC-3 (stomach) cell line, displaying 19-fold stronger activity than the positive control, adriamycin.

Natural Terpenoids as Neuroinflammatory Inhibitors in LPS-stimulated BV-2 Microglia

Neuroinflammation is a typical feature of many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Microglia, the resident immune cells of the brain, readily become activated in response to an infection or an injury. Uncontrolled and overactivated microglia can release pro-inflammatory and cytotoxic factors and are the major culprits in neuroinflammation. Hence, research on novel neuroinflammatory inhibitors is of paramount importance for the treatment of neurodegenerative diseases. Bacterial lipopolysaccharide, widely used in the studies of brain inflammation, initiates several major cellular activities that critically contribute to the pathogenesis of neuroinflammation. This review will highlight the progress on terpenoids, an important and structurally diverse group of natural compounds, as neuroinflammatory inhibitors in lipopolysaccharidestimulated BV-2 microglial cells over the last 20 years.

Ergosta-7,9(11),22-trien-3β-ol Alleviates Intracerebral Hemorrhage-Induced Brain Injury and BV-2 Microglial Activation

Intracerebral hemorrhage (ICH) is a devastating neurological disorder characterized by an exacerbation of neuroinflammation and neuronal injury, for which few effective therapies are available at present. Inhibition of excessive neuroglial activation has been reported to alleviate ICH-related brain injuries. In the present study, the anti-ICH activity and microglial mechanism of ergosta-7,9(11),22-trien-3β-ol (EK100), a bioactive ingredient from Asian medicinal herb Antrodia camphorate, were evaluated. Post-treatment of EK100 significantly attenuated neurobehavioral deficit and MRI-related brain lesion in the mice model of collagenase-induced ICH. Additionally, EK100 alleviated the inducible expression of cyclooxygenase (COX)-2 and the activity of matrix metalloproteinase (MMP)-9 in the ipsilateral brain regions. Consistently, it was shown that EK100 concentration-dependently inhibited the expression of COX-2 protein in Toll-like receptor (TLR)-4 activator lipopolysaccharide (LPS)-activated microglial BV-2 and primary microglial cells. Furthermore, the production of microglial prostaglandin E₂ and reactive oxygen species were attenuated by EK100. EK100 also attenuated the induction of astrocytic MMP-9 activation. Among several signaling pathways, EK100 significantly and concentration-dependently inhibited activation of c-Jun N-terminal kinase (JNK) MAPK in LPS-activated microglial BV-2 cells. Consistently, ipsilateral JNK activation was markedly inhibited by post-ICH-treated EK100 in vivo. In conclusion, EK100 exerted the inhibitory actions on microglial JNK activation, and attenuated brain COX-2 expression, MMP-9 activation, and brain injuries in the mice ICH model. Thus, EK100 may be proposed and employed as a potential therapeutic agent for ICH.

Coriandrum sativum attenuates microglia mediated neuroinflammation and MPTP-induced behavioral and oxidative changes in Parkinson's disease mouse model

Coriandrum sativum Linn. (family: Umbelliferae; C. sativum), is a potential herb widely used as a spice and traditional medicine. In the present work, the effects of C. sativum fruit extract (CSE), against lipopolysaccharide (LPS)-stimulated BV-2 microglia-mediated neuroinflammation in vitro and 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) animal model in vivo was investigated. LPS-stimulated increase in nitric oxide (NO), inducible NO synthase, cyclooxygenase-2, interleukin-6 and tumor necrosis factor-alpha were significantly (p < 0.05 ~ p < 0.001) inhibited by CSE (25, 50 and 100 μg/mL) in BV-2 microglial cells. Further, CSE inhibited the LPS-induced nuclear factor of kappa-beta activation and IκB-α phosphorylation in BV-2 microglia. In vivo studies, CSE (100, 200 and 300 mg/kg) ameliorated the MPTP (25 mg/kg, i.p.)-induced changes in locomotor, cognitive and behavior functions evaluated by rotarod, passive avoidance and open field test significantly (p < 0.05 ~ p < 0.001). The MPTP-induced changes in brain oxidative enzyme levels such as superoxide dismutase, catalase, and lipid peroxidation were significantly (p < 0.01 and p < 0.001 at 200 and 300 mg/kg, respectively) restored with CSE treatment. High-performance thin-layer chromatography fingerprinting analysis of CSE exhibited several distinctive peaks with quercetin and kaempferol-3O-glucoside as identifiable compounds. In conclusion, our study indicated that CSE attenuated neuroinflammatory processes in LPS-stimulated microglia in vitro and restored the MPTP-induced behavioral deficits and brain oxidative enzyme status in vivo proving its therapeutic potential in the treatment of neuroinflammatory and oxidative stress-mediated neurodegeneration seen in PD.

Anti-Neuroinflammatory Agent, Restricticin B, from the Marine-Derived Fungus Penicillium janthinellum and Its Inhibitory Activity on the NO Production in BV-2 Microglia Cells

A new compound containing a triene, a tetrahydropyran ring and glycine ester functionalities, restricticin B (1), together with four known compounds (2–5) were obtained from the EtOAc extract of the marine-derived fungus Penicillium janthinellum. The planar structure of 1 was determined by detailed analyses of MS, 1D and 2D NMR data. The relative and absolute configurations of 1 were established via the analyses of NOESY spectroscopy data, the comparison of optical rotation values with those of reported restricticin derivatives and electronic circular dichroism (ECD). All the compounds were screened for their anti-neuroinflammatory effects in lipopolysaccharide (LPS)-induced BV-2 microglia cells. Restricticin B (1) and N-acetyl restricticin (2) exhibited anti-neuroinflammatory effects by suppressing the production of pro-inflammatory mediators in activated microglial cells.

Dopamine attenuates lipopolysaccharide-induced expression of proinflammatory cytokines by inhibiting the nuclear translocation of NF-κB p65 through the formation of dopamine quinone in microglia

Many reports have indicated that dopamine has immunomodulatory effects on peripheral immune cells. The purpose of this study was to reveal the immunomodulatory effect of dopamine on the expression of proinflammatory cytokines in microglial cells, which are the immune cells of the central nervous system. In murine microglial cell line BV-2 cells, pretreatment with dopamine for 24 h attenuated the lipopolysaccharide (LPS)-induced expression of proinflammatory cytokines such as tumor-necrosis factor-α, interleukin-1β, and interleukin-6. Neither (5R)-8-chloro-3-methyl-5-phenyl-1,2,4,5-tetrahydro-3-benzazepin-7-ol; hydrochloride (SCH-23390) nor sulpiride, which are dopamine D₁-like and D₂-like receptor antagonists, respectively, affected the attenuation of LPS-induced expression of cytokines by dopamine. In addition, pretreatment with neither (-)-(6aR,12bR)-4,6,6a,7,8,12b-Hexahydro-7-methylindolo[4,3-a]phenanthridin (CY208-243) nor bromocriptine, dopamine D₁-like and D₂-like receptor agonists, respectively, was effective in doing so. However, N-acetylcysteine (NAC), which inhibits dopamine oxidation to dopamine quinone, did inhibit this attenuated expression. Dopamine increased the level of quinoproteins, and this increase was inhibited by NAC. Western blot and immunocytochemical analyses revealed that dopamine inhibited LPS-induced nuclear translocation of nuclear factor-kappa B (NF-κB) p65. Dopamine also attenuated the expression of cytokines and the nuclear translocation of NF-κB p65 induced by LPS in mouse microglial cells in primary culture. These results suggest that dopamine attenuated LPS-induced expression of cytokines by inhibiting the nuclear translocation of NF-κB p65 through the formation of dopamine quinone in microglial cells.

MCP-induced protein 1 attenuates sepsis-induced acute lung injury by modulating macrophage polarization via the JNK/c-Myc pathway

Sepsis is a potentially fatal systemic inflammatory response syndrome caused by infection. In this study, we evaluated the effects of MCP-induced protein 1 (MCPIP1), a recently discovered inflammation-related ribonuclease, on sepsis-induced acute lung injury (ALI) and investigated the underlying mechanisms. Cecal ligation puncture and lipopolysaccharide induction were performed on Sprague-Dawley rats and RAW264.7 cells, respectively, to establish sepsis-induced ALI models. The proteasome inhibitor MG132 used as an activator of MCPIP1 overexpression, and we showed that MG132 can indeed increase the expression of MCPIP1. MCPIP1 overexpression induced by MG132 alleviated sepsis-induced pathologic changes, water content and protein leakage in the lungs, and induction of systemic inflammatory mediators, and improved the 7-day mortality rate in the model rats. We also showed that MCPIP1 p showed romoted macrophage polarization from the M1 to the M2 type in sepsis-induced ALI. Furthermore, MCPIP1-enhanced M2 polarization was inhibited by an MCPIP1-targeting small interfering RNA (siMCPIP1) in RAW264.7 cells. Further mechanistic studies showed that the promotive effect of MCPIP1 on M2 polarization was related to the inhibition of c-Jun N-terminal kinase (JNK) and its downstream transcription factor c-Myc in the in vitro model. Conversely, siMCPIP1 transfection resulted in the recovery of JNK and c-Myc expression in LPS-treated cells. Taken together, these findings indicate that MCPIP1 plays a protective role in sepsis-induced ALI by modulating macrophage polarization through inhibition of the JNK/c-Myc signaling pathway. Our study presents a potentially novel therapeutic strategy for the treatment of lung injury involving the inflammatory cascade.

Trans-Cinnamaldehyde Inhibits IL-1β-Stimulated Inflammation in Chondrocytes by Suppressing NF-κB and p38-JNK Pathways and Exerts Chondrocyte Protective Effects in a Rat Model of Osteoarthritis

Objective

Trans-cinnamaldehyde (TCA), a compound from Cinnamomum cassia Presl, has been reported to have anti-inflammatory effect. However, its effect on cartilage degradation in osteoarthritis is unclear. This study is designed to examine the effects of TCA on cartilage in vitro and in vivo.

Material and Methods

SW1353 cells and human primary chondrocytes were treated with varying concentrations of TCA (2-20 μg/ml) for 2 h followed by IL-1β stimulation. Cell viability was examined by the MTT assay. Expression of MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 was examined by Western blot and RT-qPCR. Monosodium iodoacetate (MIA)-induced OA was established in rats to assess the chondrocyte protective effects of intraperitoneal injection of TCA (50 mg/kg).

Results

TCA at a concentration of 10 μg/ml had no significant effect on cell viability. MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 were decreased by TCA 2-10 μg/ml in a dose-dependent manner (all P<0.05). Pretreatment with TCA decreased the degradation of IκBα and increased the expression of p-IκBα, indicating that NF-κB inactivation was induced by TCA in IL-1β-stimulated SW1353 cells. Pretreatment with TCA decreased the levels of p-p38 and p-JNK, while the levels of p-ERK were not significantly affected. TCA 10 μg/ml significantly decreased expression levels of MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5. In vivo results showed that TCA alleviated cartilage destruction and the OARSI scores.

Conclusion

TCA possesses anti-inflammatory effect in vitro and exerts chondrocyte protective effects in vivo, in which NF-κB and p38-JNK were involved.

Aqueous Extract of Dendropanax morbiferus Leaves Effectively Alleviated Neuroinflammation and Behavioral Impediments in MPTP-Induced Parkinson's Mouse Model

Parkinson's disease (PD) is a commonly reported age-related neurodegenerative disorder. Microglial-mediated neuroinflammation is one of the cardinal hallmarks of various neurodegenerative disorders, including PD progression. Inadequate therapeutic strategies and substantial adverse effects of well-established drug candidates demand new therapeutic leads to treat PD. Dendropanax morbifera (DM) is an endemic plant species of South Korea, and it has been used extensively as traditional medicine to treat numerous clinical complications. In this study, we conducted an initial profiling of the few major phytoconstituents of aqueous DM leaf extracts (DML) and quantified the same using high-performance liquid chromatography tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS). We subsequently evaluated the antineuroinflammatory activity and ameliorative potential of DML in both in vitro and in vivo experimental PD models. The prophylactic treatment of DML effectually improved the behavioral deficits, curbed the microglial-mediated neuroinflammation, and protected dopaminergic (DA) neuronal loss by restoring tyrosine hydroxylase (TH) levels in brain tissue of the MPTP-induced PD mouse model. We conducted chromatographic profiling and identified chlorogenic acid (CA) as a major constituent (19.5 mg/g of BuOH fraction), which has been well documented as an antioxidant and anti-inflammatory agent. This was found to be in harmony with our in vitro results, where DML suppressed the level of inflammatory mediators and allied the signaling pathway in LPS-stimulated microglial cells. The results of our study indicate that DML and its bioactive constituents can be developed as potential therapeutic candidates against progressive PD complications.

Xanthoceraside attenuates amyloid β peptide1-42-induced memory impairments by reducing neuroinflammatory responses in mice

Xanthoceraside, a novel triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge, has neuroprotective effects in vivo and anti-inflammatory properties in vitro. However, the exact mechanism of xanthoceraside on anti-amyloid beta (Aβ)-induced neuroinflammatory responses has not been elucidated. Therefore, we used intracerebroventricular injection of amyloid _1-42 (Aβ_1-42) to establish a mouse model to test the effects of xanthoceraside on Aβ-induced cognitive impairments and the TLR2/NF-κB and MAPK pathways. The mice received xanthoceraside (0.02, 0.08 or 0.32mg/kg) or vehicle from the day of Aβ_1-42 injection. The Morris water maze test was performed 4 days after Aβ_1-42 injection. The levels of inflammatory cytokines (interleukin (IL)-6 and IL-4) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of glial fibrillary acidic protein (GFAP) and cluster of differentiation 11b (CD11b) in the hippocampus were determined with an immunohistochemistry assay. Inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) were analysed by Western blotting; iNOS, COX-2 and Toll-like receptor 2 (TLR2) mRNA expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR). Here, we observed that xanthoceraside at doses of 0.08 and 0.32mg/kg significantly improved learning and memory impairments and significantly inhibited GFAP and CD11b overexpression induced by Aβ_1-42 in mice. ELISA results revealed that xanthoceraside suppressed IL-6 release and increased IL-4 levels. Western blotting results showed that xanthoceraside reduced iNOS and COX-2 protein levels in hippocampus; xanthoceraside also inhibited translocation of NF-κB p50 and p65 into the nucleus and phosphorylation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38. RT-PCR confirmed that xanthoceraside decreased iNOS, COX-2 and TLR2 mRNA levels. These results suggest that xanthoceraside inhibition of the TLR2 pathway and down-regulation of MAPK and NF-κB activities may be related to the improvement in learning and memory impairments.

α-Asarone attenuates microglia-mediated neuroinflammation by inhibiting NF kappa B activation and mitigates MPTP-induced behavioral deficits in a mouse model of Parkinson's disease

The selective loss of dopaminergic neurons in Parkinson's disease (PD) is associated with microglial activation. Therefore, the importance of early therapeutic intervention to inhibit microglial activation would be an effective strategy to alleviate the progression of PD. α-Asarone, an active compound found in Araceae and Annonaceae plant species has been used to improve various disease conditions including central nervous system disorders. In the present study the in vitro and in vivo therapeutic effects of α-asarone isolated from the rhizome of Acorus gramineus Solander was evaluated on microglia-mediated neuroinflammation and neuroprotection. Lipopolysaccharide (LPS)-stimulated BV-2 microglial cells were used to evaluate in vitro effects. 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced mouse model of PD was developed to study the neuroprotective effects of α-asarone in vivo. The results indicated that α-asarone significantly attenuated the LPS-stimulated increase in neuroinflammatory responses and suppressed pro-inflammatory cytokine production in BV-2 cells. Mechanistic study revealed that α-asarone inhibited the LPS-stimulated activation via regulation of nuclear factor kappa-B by blocking degradation of inhibitor kappa B-alpha signaling in BV-2 microglial cells. In in vivo studies, MPTP intoxication to mice resulted in brain microglial activation and significant behavioral deficits. Prophylactic treatment with α-asarone suppressed microglial activation and attenuated PD-like behavioral impairments as assessed by the Y-maze and pole tests. Taken together, these data demonstrate that α-asarone is a promising neuroprotective agent that should be further evaluated and developed for future prevention and treatment of microglia-mediated neuroinflammatory conditions including PD.

Attenuation of neuroinflammatory responses and behavioral deficits by Ligusticum officinale (Makino) Kitag in stimulated microglia and MPTP-induced mouse model of Parkinson's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Ligusticum officinale (Makino) Kitag (L. officinale) is one of the important traditional herbs used in traditional Oriental medicine for the treatment of various disorders including pain and inflammation. However, there is limited scientific basis for its activity and mechanism in brain inflammation.

AIM OF THE STUDY

This study aimed to evaluate the effects of L. officinale on microglia-mediated neuroinflammation and behavioral impairments using in vitro cellular and in vivo mouse model of PD, as well as investigate the molecular mechanisms involved including the finger printing analysis of its ethanol extract.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) was used to stimulate BV-2 microglial cells. The changes in neuroinflammatory expressional levels were measured by Western blotting and immunofluorescence techniques. 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-intoxicated mice model of PD was developed to evaluate the behavioral impairments and the brain tissues were used for immunohistochemical studies. High performance liquid chromatography (HPLC) technique was performed for finger printing analysis of L. officinale extract used in the study.

RESULTS

L. officinale significantly attenuated the LPS-stimulated increase in inflammatory mediators in BV-2 cells. L. officinale also inhibited the LPS-induced activation of nuclear factor-kappa beta by blocking the degradation of IκB-α and suppressing the increase in p38-mitogen-activated protein kinase phosphorylation in BV-2 cells. Furthermore, L. officinale exhibited significant antioxidant properties by inhibiting the 1-diphenyl-2-picrylhydrazyl radicals. An in vivo evaluation in MPTP (20mg/kg, four times, 1 day, i.p.) intoxicated mice resulted in brain microglial activation and significant behavioral deficits. Prophylactic treatment with L. officinale prevented microglial activation and attenuated PD-like behavioral changes as assessed by the pole test. HPLC finger printing analysis revealed that L. officinale extract contained ferulic acid (FA) as one of the major constituents compared with reference standard. FA also inhibited the LPS-stimulated excessive release of NO and suppressed the increased the expressional levels of proinflammatory mediators in BV-2 microglia.

CONCLUSIONS

The findings observed in this study indicated that L. officinale extract significantly attenuated the neuroinflammatory processes in stimulated microglia and restored the behavioral impairments in a mouse model of PD providing a scientific basis for its traditional claims.

Anti-inflammatory effects of glaucocalyxin B in microglia cells

Over-activated microglia is involved in various kinds of neurodegenerative process including Parkinson, Alzheimer and HIV dementia. Suppression of microglial over activation has emerged as a novel strategy for treatment of neuroinflammation-based neurodegeneration. In the current study, anti-inflammatory and neuroprotective effects of the ent-kauranoid diterpenoids, which were isolated from the aerial parts of Rabdosia japonica (Burm. f.) var. glaucocalyx (Maxim.) Hara, were investigated in cultured microglia cells. Glaucocalyxin B (GLB), one of five ent-kauranoid diterpenoids, significantly decreased the generation of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in the lipopolysaccharide (LPS)-activated microglia cells. In addition, GLB inhibited activation of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS) in LPS-activated microglia cells. Furthermore, GLB strongly induced the expression of heme oxygenase (HO)-1 in BV-2 microglia cells. Finally, GLB exhibited neuroprotective effect by preventing over-activated microglia induced neurotoxicity in a microglia/neuron co-culture model. Taken together, the present study demonstrated that the GLB possesses anti-nueroinflammatory activity, and might serve as a potential therapeutic agent for treating neuroinflammatory diseases.

Anti-neuroinflammatory effects of DPTP, a novel synthetic clovamide derivative in in vitro and in vivo model of neuroinflammation

Neuroinflammation is one of the critical pathological mechanisms influencing various neurodegenerative disorders. Most of the neurodegenerative diseases involve over-activation of microglial cells contributing to the demise of neurons. The objective of the current study is to evaluate the anti-inflammatory effect of novel synthetic clovamide derivative on the suppression of microglial activation in an in vitro and in vivo model of neuroinflammation. We have used lipopolysaccharide (LPS) to induce an inflammatory response in murine BV-2 microglial cells. Molecular tools like immunocytochemistry and immunoblotting were used to study the activity of novel synthetic clovamide derivative to inhibit inflammation induced by LPS in microglial cells. In in vivo experiments, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mouse model of neuroinflammation was developed to investigate the anti-neuroinflammatory effects of DPTP [3-(3,4-Dihydroxy-phenyl)-2-[4-(3-trifluoromethylphenyl)-but-2-enoylamino]-propionic acid methyl ester]. DPTP was observed to reduce the proinflammatory response in BV-2 cells induced by LPS. Further investigation revealed that DPTP attenuated phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), which was accompanied by a decrease in nuclear translocation of nuclear factor-κB (NF-κB) in LPS-treated BV2 microglia. Moreover, prophylactic treatment with DPTP (20mg/kg) for 7 days suppressed MPTP induced glial activation and behavioral impairment. Overall, our findings suggested that, DPTP exerts anti-neuroinflammatory effects against activated microglia in an in vitro and in vivo model and hence might be a promising therapeutic agent for alleviating the evolvement of neurodegenerative diseases associated with microglial activation.

EOP, a newly synthesized ethyl pyruvate derivative, attenuates the production of inflammatory mediators via p38, ERK and NF-κB pathways in lipopolysaccharide-activated BV-2 microglial cells

Microglia-induced neuroinflammation is an important pathological mechanism influencing various neurodegenerative disorders. Excess activation of microglia produces a myriad of proinflammatory mediators that decimate neurons. Hence, therapeutic strategies aimed to suppress the activation of microglia might lead to advancements in the treatment of neurodegenerative diseases. In this study, we synthesized a novel ethyl pyruvate derivative, named EOP (S-ethyl 2-oxopropanethioate) and studied its effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in rat primary microglia and mouse BV-2 microglia. EOP significantly decreased the production of NO, inducible nitric oxide synthase, cyclooxygenase and other proinflammatory cytokines, such as interleukin (IL)-6, IL-1β and tumor necrosis factor-α, in LPS-stimulated BV-2 microglia. The phosphorylation levels of extracellular regulated kinase, p38 mitogen-activated protein kinase, and nuclear translocation of NF-κB were also inhibited by EOP in LPS-activated BV-2 microglial cells. Overall, our observations indicate that EOP might be a promising therapeutic agent to diminish the development of neurodegenerative diseases associated with microglia activation.

JNK inhibitor SP600125 protects against lipopolysaccharide-induced acute lung injury via upregulation of claudin-4

Although in vitro studies have previously demonstrated that mitogen-activated protein kinases are important for the activation of transcription factors and the regulation of proinflammatory mediators, the function of c-Jun NH₂-terminal kinase (JNK) in acute lung injury (ALI) remains to be fully elucidated. The present study aimed to investigate the effect of the JNK selective inhibitor SP600125 on lipopolysaccharide (LPS)-induced ALI. Pulmonary edema, the expression of inflammatory cytokines and pathological alterations were found to be significantly attenuated in LPS-induced ALI following treatment with SP600125 in vivo. In vitro, it was demonstrated that SP600125 administration significantly improved A549 cell viability in a dose-dependent manner using the Cell Counting kit-8 and the 5-ethynyl-2'-deoxyuridine incorporation assay. Furthermore, flow cytometric analysis demonstrated that the apoptotic rate was significantly reduced in a concentration-dependent manner following SP600125 injection. At the molecular level, SP600125 treatment dose-dependently inhibited JNK activation and upregulated claudin-4 expression in vivo and in vitro. In combination, the results from the present study indicated that the JNK inhibitor SP600125 protected against LPS-induced ALI in vivo and in vitro, possibly by upregulating the expression of claudin-4.

A novel synthetic HTB derivative, BECT inhibits lipopolysaccharide-mediated inflammatory response by suppressing the p38 MAPK/JNK and NF-κB activation pathways

Activated microglia cells are well recognized as mediators of neuroinflammation, as they release nitric oxide and pro-inflammatory cytokines in various neuroinflammatory diseases. Thus, suppressing microglial activation may alleviate neuroinflammatory and neurodegenerative processes. In the present study, we synthesized and investigated the anti-neuroinflammatory effect of a novel HTB (2-hydroxy-4-trifuoromethylbenzoic acid) derivative in lipopolysaccharide (LPS)-stimulated microglial cells. Among the synthesized derivatives, the BECT [But-2-enedioic acid bis-(2-carboxy-5-trifluoromethyl-phenyl) ester] significantly decreased production of nitric oxide and other pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6 in microglial cells. BECT also mitigated the expression of inducible nitric oxide synthase and cyclooxygenase-2 at both the mRNA and protein levels. Further mechanistic studies demonstrated that the HTB derivative inhibited phosphorylation of JNK and p38 mitogen-activated protein kinase and nuclear translocation of nuclear factor kappa-B in LPS-stimulated BV-2 microglial cells. Thus BECT, our novel synthesized compound have anti-inflammatory activity in microglial cells, and may have therapeutic potential for treating neuroinflammatory diseases.

Regulation of microglia activity by glaucocalyxin-A: attenuation of lipopolysaccharide-stimulated neuroinflammation through NF-κB and p38 MAPK signaling pathways

Microglial cells are the resident macrophages and intrinsic arm of the central nervous system innate immune defense. Microglial cells become activated in response to injury, infection, environmental toxins, and other stimuli that threaten neuronal survival. Therefore, regulating microglial activation may have therapeutic benefits that lead to alleviating the progression of inflammatory-mediated neurodegeneration. In the present study, we investigated the effect of glaucocalyxin A (GLA) isolated from Rabdosia japonica on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated primary microglia and BV-2 cells. GLA significantly inhibited LPS-induced production of nitric oxide and reversed the morphological changes in primary microglia. Further, GLA suppressed expression of inducible nitric oxide synthase and cyclooxygenase-2 dose-dependently at the mRNA and protein levels. The production of proinflammatory cytokines such as tumor necrosis factor-α, interleukin-1β (IL)-1β, and IL-6 were inhibited by suppressing their transcriptional activity. Furthermore, GLA suppressed nuclear factor-κB activation by blocking degradation of IκB-α and inhibited the induction of lipocalin-2 expression in LPS-stimulated BV-2 cells. Mechanistic study revealed that the inhibitory effects of GLA were accompanied by blocking the p38 mitogen activated protein kinase signaling pathway in activated microglia. In conclusion, given that microglial activation contributes to the pathogenesis of neurodegenerative diseases, GLA could be developed as a potential therapeutic agent for treating microglia-mediated neuroinflammatory diseases.

Study on the immunomodulation effect of Isodon japonicus extract via splenocyte function and NK anti-tumor activity

Here we investigated the potential immune-enhancing activity of Isodon japonicus on murine splenocyte and natural-killer (NK) cells in vitro. The ethanol extract of I. japonicus significantly enhanced the proliferation of splenocyte and induced the significant enhancement of NK cells' activity against tumor cells (YAC-1). In addition, I. japonicus increased the production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α, suggesting that the increase in NK cell cytotoxicity could be due to the enhancement of the NK cell production of both cytokines. Taken together, I. japonicus extract inhibited the growth of human leukemia cells (K562) by 74%. Our observation indicated that the anti-tumor effects of I. japonicus may be attributed to its ability to serve as a stimulant of NK anti-tumor activity. In addition, our results support the development of functional food studies on I. japonicus.