Anti-neuroinflammatory effect of Sophoraflavanone G from Sophora alopecuroides in LPS-activated BV2 microglia by MAPK, JAK/STAT and Nrf2/HO-1 signaling pathways

Methyl Jasmonate Protects Microglial Cells Against β-Amyloid-Induced Oxidative Stress and Inflammation via Nrf2-Dependent HO-1 Pathway

BACKGROUND

β-Amyloid (Aβ) induces oxidative stress and inflammation of microglial cells, thus leading to Alzheimer's disease. Methyl jasmonate (MeJA) is reported to have anti-inflammatory and anti-oxidant effects. However, the potential roles of MeJA in Aβ-induced cell activities and the underlying mechanism are unclear.

METHODS

Microglial cell line BV-2 was stimulated by 20 μM Aβ and/or 20 μM MeJA and then divided into four groups (control, Aβ, MeJA, and Aβ+MeJA). Cell viability was detected by MTT assay. MDA, SOD activity, and ROS were detected by fluorescence spectrophotometry and immunofluorescence assay. Nrf2 and HO-1 were detected by qRT-PCR and Western blot. Furthermore, inflammatory cytokines (p-NFκB, TLR4, TNF-α, IL-1β, and IL-6) and apoptosis factors (Bcl-2, Bax, and cl-casp-3) were detected by Western blot. TUNEL assay was applied to investigate apoptosis rate. Moreover, the mechanism of how MeJA played anti-oxidative stress and anti-inflammatory roles was investigated by silencing of Nrf2 via siRNA.

RESULTS

The result of MTT assay showed that MeJA improved the decreased viability of BV-2 cells induced by Aβ. The detection of MDA, SOD activity, and ROS showed the oxidative stress levels were decreased in Aβ+MeJA group compared with Aβ group. Nrf2, HO-1, and SOD were significantly up-regulated in Aβ+MeJA group compared with Aβ group (p<0.01). In contrast, inflammatory cytokines were significantly down-regulated in Aβ+MeJA group compared with Aβ group (p<0.05). Similarly, the expressions of apoptosis cytokines and TUNEL assay suggested a decreased apoptosis rate in Aβ+MeJA group compared to Aβ group (p<0.01). Finally, results of Nrf2 knockdown experiment showed down-regulations of anti-oxidative stress factors (Nrf2, HO-1 and SOD), up-regulations of inflammatory cytokines, and increased ratio of Bax to Bcl in Aβ+MeJA+si-Nrf2 group compared with Aβ+MeJA group (p<0.01).

CONCLUSION

MeJA could relieve Aβ-induced oxidative stress and inflammatory response in microglial cells by activating Nrf2/HO-1 pathway.

The pharmacology of the genus Sophora (Fabaceae): An updated review

BACKGROUND

The genus Sophora (Fabaceae) represents one of the important medicinal plant genera regarding its chemical constituents and outstanding pharmacological activities.

PURPOSE

In this review, we surveyed the latest findings on the bioactivities of different Sophora extracts and isolated phytochemicals during the past 8 years (2011-2019) updating the latest review article in 2011. The aim of this review is to focus on the molecular pharmacology of Sophora species to provide the rationale basis for the development of novel drugs.

RESULTS

Sophora and its bioactive compounds possess outstanding pharmacological properties, especially as anticancer and anti-inflammatory drugs, in addition to its antioxidant, antibacterial, antifungal and antiviral properties.

CONCLUSION

Based on their use in traditional medicine, Sophora species exert a plethora of cellular and molecular activities, which render them as attractive candidates for rationale drug development. Randomized, placebo-controlled clinical trials are required for further integration of Sophora-based phototherapies into conventional medicine.

Essential oil of Schisandra chinensis ameliorates cognitive decline in mice by alleviating inflammation

In this study, we aim to assess possible impacts of essential oil (SEO) from Schisandra chinensis (Turcz.) Baill. (S. chinensis) on mice with cognition impairment. Our data showed that SEO improved the cognitive ability of mice with Aβ_1-42 or lipopolysaccharides (LPS)-induced Alzheimer's disease (AD) and suppressed the production of tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in the hippocampus. Furthermore, SEO inhibited p38 activation, but had little effect on other signaling proteins in the MAPK family, such as extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase 1/2 (JNK). The SEO and BV-2 microglia co-culture was performed to further confirm the anti-inflammatory activity of SEO. The data showed that SEO decreased nitric oxide (NO) levels in LPS-stimulated BV-2 microglia and significantly blocked LPS-induced MAPKs activation. Taken together, these findings suggested that SEO produces anti-AD effects on AD mice partly by modulating neuroinflammation through the NF-κB/MAPK signaling pathway.

Protein kinase C is involved in the neuroprotective effect of berberine against intrastriatal injection of quinolinic acid-induced biochemical alteration in mice

Protein kinase C (PKC) shows a neuronal protection effect in neurodegenerative diseases. In this study, we test whether berberine has a positive effect on the activity of PKC in quinolinic acid (QA)‐induced neuronal cell death. We used intrastriatal injections of QA mice model to test the effect of berberine on motor and cognitive deficits, and the PKC signalling pathway. Treatment with 50 mg/kg b.w of berberine for 2 weeks significantly prevented QA‐induced motor and cognitive impairment and related pathologic changes in the brain. QA inhibited the phosphorylation of PKC and its downstream molecules, GSK‐3β, ERK and CREB, enhanced the glutamate level and release of neuroinflammatory cytokines; these effects were attenuated by berberine. We used in vivo infusion of Go6983, a PKC inhibitor to disturb PKC activity in mice brain, and found that the effect of berberine to reverse motor and cognitive deficits was significantly reduced. Moreover, inhibition of PKC also blocked the anti‐excitotoxicity effect of berberine, which is induced by glutamate in PC12 cells and BV2 cells, as well as anti‐neuroinflammatory effect in LPS‐stimulated BV2 cells. Above all, berberine showed neuroprotective effect against QA‐induced acute neurotoxicity by activating PKC and its downstream molecules.

Natural Inhibitors on Over-Activation of Microglia from Herbals

Neuroinflammation manifested by over-activation of microglial cells plays an essential role in neurodegenerative diseases. Short-term activation of microglia can be beneficial, but chronically activated microglia can aggravate neuronal dysfunction possibly by secreting potentially cytotoxic substances such as tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO), which can result in dysfunction and death of neurons. Therefore inhibiting over-activation of microglia and the production of cytotoxic intermediates may become an effective therapeutic approach for neuroinflammation. In this paper, we review our continuous research on natural inhibitors of over-activated microglia from traditional herbals, including flavonoids, lignans, sesquiterpene coumarins, and stilbenes.

Melatonin attenuates expression of cyclooxygenase-2 (COX-2) in activated microglia induced by lipopolysaccharide (LPS)

Lipopolysaccharide (LPS) is a known neurotoxin and utilized most extensively as a microglial activator for induction of inflammatory neurodegeneration. Melatonin (MEL) is the main secretory product of pineal gland reported to be responsible for a variety of physiological functions. However, the molecular mechanisms underlying the influence of MEL on microglia activation remain unclear. The aim of this study was to investigate the effect of MEL on cyclooxygenase-2 (COX-2) levels in LPS-induced microglia. The results of RT-PCR and Western blot analysis showed that MEL significantly inhibited LPS-mediated upregulation of COX-2 in microglia. Data from ELISA demonstrated that prostaglandin E2 (PGE2), the downstream effector of COX-2, concentrations were also reduced. In addition, MEL was found to decrease activation of ERK1/2, JNK, p38 MAPK, and NF-κB, the upstream signal pathways of COX-2. Taken together, evidence indicates that MEL may attenuate upregulation of COX-2 by blocking the MAPK/NF-κB signaling pathway in LPS-stimulated microglia.

Structural elucidation and bioactivities of a novel arabinogalactan from Coreopsis tinctoria

Coreopsis tinctoria is being widely cultivated in Xinjiang of China, whose consumption is known to prevent diabetes and neurodegenerative diseases. To elucidate the bioactive ingredients responsible for these benefits, the alkaline soluble crude polysaccharide (CTB) was isolated from C. tinctoria. In vitro experiments showed that the inhibition of α-amylase and α-glucosidase by CTB was 13407-fold and 906-fold higher than that by positive control, respectively. Then, a novel arabinogalactan, CTBP-1, was isolated and purified from CTB. Structural analysis showed that CTBP-1 possessed a 1,6-linked β-d-Galp and 1,5-linked α-l-Araf backbone with branches substituted at the C-3 position of the 1,6-linked β-d-Galp, and the side chains included 1,5-linked α-l-Araf, T-linked β-d-Galp and T-linked α-l-Araf. The inhibitory effects of CTBP-1 on α-amylase and α-glucosidase were 2.7 and 17.9 times that of acarbose, respectively. CTBP-1 could avoid indigestion and similar side effects. In addition, CTBP-1 remarkably inhibited the release of nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. In summary, CTBP-1 is a novel arabinogalactan with great potential as a treatment for type 2 diabetes and Alzheimer's disease.

Marine Compound 3-bromo-4,5-dihydroxybenzaldehyde Protects Skin Cells against Oxidative Damage via the Nrf2/HO-1 Pathway

In this study, we aimed to illustrate the potential bio-effects of 3-bromo-4,5-dihydroxybenzaldehyde (3-BDB) on the antioxidant/cytoprotective enzyme heme oxygenase-1 (HO-1) in keratinocytes. The antioxidant effects of 3-BDB were examined via reverse transcription PCR, Western blotting, HO-1 activity assay, and immunocytochemistry. Chromatin immunoprecipitation analysis was performed to test for nuclear factor erythroid 2-related factor 2 (Nrf2) binding to the antioxidant response element of the HO-1 promoter. Furthermore, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that the cytoprotective effects of 3-BDB were mediated by the activation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, Akt) signaling. Moreover, 3-BDB induced the phosphorylation of ERK and Akt, while inhibitors of ERK and Akt abrogated the 3-BDB-enhanced levels of HO-1 and Nrf2. Finally, 3-BDB protected cells from H₂O₂- and UVB-induced oxidative damage. This 3-BDB-mediated cytoprotection was suppressed by inhibitors of HO-1, ERK, and Akt. The present results indicate that 3-BDB activated Nrf2 signaling cascades in keratinocytes, which was mediated by ERK and Akt, upregulated HO-1, and induced cytoprotective effects against oxidative stress.

The Antioxidant from Ethanolic Extract of Rosa cymosa Fruits Activates Phosphatase and Tensin Homolog In Vitro and In Vivo: A New Insight on Its Antileukemic Effect

Rosa cymosa Tratt is a Chinese herbal remedy that is used in the treatment of diarrhea, burns, rheumatoid arthritis, and hemorrhage. Despite its use in Asian folk medicine, there are limited reports on the biological activity of R. cymosa fruits. This study focused on the investigation of the antitumor effect of the antioxidative ethanolic extract of R. cymosa fruits (RCE) along with its underlying mechanism of action. RCE showed a potent cytotoxic effect against Sup-T1 and Molt-4 lymphoblastic leukemia cells. In the xenograft animal model, the tumor size was significantly reduced to about 59.42% in the RCE-treated group in comparison with the control group. The use of RCE (37.5, 75, or 150 μg/mL) triggered apoptosis by 26.52–83.49%, disrupted mitochondrial membrane potential (MMP) by 10.44–58.60%, and promoted calcium release by 1.29-, 1.44-, and 1.71-fold compared with the control group. The extract induced redox oxygen species (ROS) generation through the elimination of Nrf2/Keap1/P62-mediated oxidative stress response. The loss of phosphatase and tensin homolog (PTEN) activation by RCE impaired PI3K/Akt/Foxo and Jak/Stat activation pathways, which contributed to tumorigenesis. These multiple targets of R. cymosa against hematologic cancer cells suggested its potential application as an antileukemic dietary supplement.

Antineuroinflammatory and Neuroprotective Effects of Gyejibokryeong-Hwan in Lipopolysaccharide-Stimulated BV2 Microglia

Microglia, the central nervous system's innate immune cells, mediate neuroinflammation and are implicated in a variety of neuropathologies. The present study investigated the antineuroinflammatory and neuroprotective effects of Gyejibokryeong-hwan (GBH), a traditional Korean medicine, in lipopolysaccharide- (LPS-) stimulated murine BV2 microglia. BV2 cells were pretreated with GBH, fluoxetine (FXT), or amitriptyline (AMT) for 1 h and then stimulated with LPS (100 ng/mL). The expression levels of nitric oxide (NO), cytokines, and chemokines were determined by the Griess method, ELISA, or real-time PCR. Western blotting was used to measure various transcription factors and mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt activity. GBH significantly reduced the levels of NO, inducible nitric oxide synthase (iNOS), cyclooxygenase- (COX-) 2, tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, macrophage inhibitory protein- (MIP-) 1α, macrophage chemoattractant protein- (MCP-) 1, and IFN-γ inducible protein- (IP-) 10, regulated upon activation normal T cell expressed sequence (RANTES) in a dose-dependent manner. Expression of nuclear factor- (NF-) κB p65 was significantly decreased and phosphorylation of extracellular signal-regulated kinase (Erk), c-Jun NH2-terminal kinase (JNK), and PI3K/Akt by GBH, but not p38 MAPK, was decreased. Furthermore, production of anti-inflammatory cytokine IL-10 was increased and Heme oxygenase-1 (HO-1) was upregulated via the nuclear factor-E2-related factor 2 (NRF2)/cAMP response element-binding protein (CREB) pathway, collectively indicating the neuroprotective effects of GBH. We concluded that GBH may suppress neuroinflammatory responses by inhibiting NF-κB activation and upregulating the neuroprotective factor, HO-1. These results suggest that GBH has potential as anti-inflammatory and neuroprotective agents against microglia-mediated neuroinflammatory disorders.

Chemical Constituents and an Antineuroinflammatory Lignan, Savinin from the Roots of Acanthopanax henryi

The phytochemical investigation on the roots of Acanthopanax henryi (Araliaceae) resulted in the discovery of twenty compounds whose chemical structures were elucidated by the analysis of 1D-, 2D-NMR, mass spectrometry data, other physicochemical properties, and a comparison of the spectral data with the literature. They were identified as (-)-sesamin (1), helioxanthin (2), savinin (3), taiwanin C (4), 6-methoxy-7-hydroxycoumarin (5), behenic acid (6), 3-O-caffeoyl-quinic acid (7), 5-O-caffeoyl-quinic acid (8), 1,3-di-O-caffeoyl-quinic acid (9), 1,4-di-O-caffeoyl-quinic acid (10), 1,5-di-O-caffeoyl-quinic acid (11), (+)-threo-(7R,8R)-guaiacylglycerol-β-coniferyl aldehyde ether (12), (+)-erythro-(7S,8R)-guaiacylglycerol-β-coniferyl aldehyde ether (13), ferulic acid (14), caffeic acid (15), stigmasterol (16), β-sitosterol (17), adenosine (18), syringin (19), and trans-coniferin (20). Among these isolates, compound 3 showed inhibitory activity against lipopolysaccharide- (LPS-) induced nitric oxide (NO) and prostaglandin E2 (PGE2) production with IC50 values of 2.22 ± 0.11 and 2.28 ± 0.23 μM, respectively. The effects of compound 3 were associated with the suppression of LPS-induced expression of the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein. Furthermore, compound 3 negatively regulated the production of interleukin- (IL-) 1β and tumor-necrosis factor- (TNF-) α at the transcriptional level in LPS-stimulated BV2 microglial cells. These antineuroinflammatory effects of compound 3 were mediated by p38 mitogen-activated protein kinase (MAPK).

The hepatoprotective effects of Sedum sarmentosum extract and its isolated major constituent through Nrf2 activation and NF-κB inhibition

BACKGROUND

Sedum sarmentosum, which is recorded in Chinese Pharmacopoeia, has been applied clinically to treat liver and gallbladder diseases.

PURPOSE

This study aimed to explore the hepatoprotective effect of S. sarmentosum less polar extract (SSE) against ANIT-induced liver injury in rats, and the protective activity and mechanism of one major constituent isolated from this extract on D-GalN-induced human hepatic QSG7701 cell damage.

METHODS

Rats were divided into groups and then administrated intragastrically with SSE at doses of 100, 200 and 400 mg/kg for 7 days. They were modeled in the experiments with ANIT (70 mg/kg) to induce liver injury after the sixth day administration. The levels of serum biochemical markers ALT, AST, ALP, GGT/γ-GT, DBiL, TBiL, ALB, TP, and bile flow rate, as well as the histopathology of the liver tissue were used as indices of liver damage and measured. The inflammatory response and oxidative stress were thought to be key contributors to ANIT-induced liver injury in rats. Therefore, the inflammatory mediators (TNF-α, IFN-γ, IL-4) and oxidative stress (ROS, SOD, GSH-PX) were measured in the serum and liver homogenates, respectively. Next, phytochemical research was performed to produce the main component, and the isolated compound was evaluated for its hepatoprotective activity against QSG7701 cell injured by D-GalN through the measurement of cell viabilities, ALT, AST, IL-1β, TNF-α, IL-6, ROS, GSH-PX and SOD productions. Furthermore, the protein expression of the Nrf2 and NF-κB pathways were analyzed by western blotting.

RESULTS

SSE had an obvious effect on the decreases of ALT, AST, ALP, GGT/γ-GT, DBiL and TBiL levels, the increases of ALB and TP levels in serum, and the ANIT-induced deceleration in bile flow for liver injury. Meanwhile, SSE pretreatment alleviated ANIT-induced liver pathological injuries exhibited by HE stain of the liver. Moreover, SSE significantly suppressed levels of pro-inflammatory cytokines TNF-α and IFN-γ, and elevated level of anti-inflammatory cytokine IL-4 in serum. SSE also attenuated oxidative stress by reducing ROS level and by enhancing antioxidative enzymes (SOD and GSH-PX) activities after ANIT administration in liver tissue. Further, the major compound shown in HPLC was isolated from SSE. Its structure was identified by the spectroscopic data analysis and comparison with literature values. The principal constituent had potent protective effect on D-GalN-induced QSG7701 cells damage in a dose dependent manner with survival rates of 58.2% and 69.5% at 10 μM and 20 μM, respectively. Its cytoprotective effect was associated with the reduction of ALT, AST, IL-1β, TNF-α, IL-6 and ROS levels, and the elevation of GSH-PX and SOD productions in QSG7701 cells induced by D-GalN. Western blotting showed that this compound enhanced the expression of Nrf2, HO1, NQO1 and GCLC, and inhibited D-GalN-induced IκBα and NF-κB p65 phosphorylation.

CONCLUSIONS

Current study showed that SSE treatment exerted a protective effect on ANIT-induced liver injury. The main compound δ-amyrone isolated from the extract was characterized as the effective component with hepatoprotective activity by promoting Nrf2 antioxidant defense and suppressing NF-κB inflammatory response.

Synthesis and evaluation of isoprenylation-resveratrol dimer derivatives against Alzheimer's disease

A series of resveratrol dimer derivatives against Alzheimer's disease (AD) was obtained by structural modification and transformation using resveratrol as substrate. Biological analysis revealed that these derivatives had moderate inhibitory activity against human monoamine oxidase B (hMAO-B). In particular, 3 and 7 showed the better inhibitory activity for hMAO-B (IC50 = 3.91 ± 0.23 μM, 0.90 ± 0.01 μM) respectively. Compound 3 (IC50 = 46.95 ± 0.21 μM for DPPH, 1.43 and 1.74 trolox equivalent by ABTS and FRAP method respectively), and 7 (IC50 = 35.33 ± 0.15 μM for DPPH, 1.70 and 1.97 trolox equivalent by ABTS method and FRAP method respectively) have excellent antioxidant effects. Cellular assay shown that 3 and 7 had lower toxicity and were resistant to neurotoxicity induced by oxidative toxins (H2O2, rotenone and oligomycin-A). More importantly, the selected compounds have neuroprotective effects against ROS generation, H2O2-induced apoptosis and a significant in vitro anti-inflammatory activity. The results of the parallel artificial membrane permeability assay for blood-brain barrier indicated that 3 and 7 would be predominant to cross the blood-brain barrier. In this study, mouse microglia BV2 cells were used to establish cell oxidative stress injury model with H2O2 and to explore the protective effect and mechanism of 3 and 7. In general, 3 and 7 can be considered candidates for potential treatment of AD.

Melatonin combined with chondroitin sulfate ABC promotes nerve regeneration after root-avulsion brachial plexus injury

After nerve-root avulsion injury of the brachial plexus, oxidative damage, inflammatory reaction, and glial scar formation can affect nerve regeneration and functional recovery. Melatonin (MT) has been shown to have good anti-inflammatory, antioxidant, and neuroprotective effects. Chondroitin sulfate ABC (ChABC) has been shown to metabolize chondroitin sulfate proteoglycans and can reduce colloidal scar formation. However, the effect of any of these drugs alone in the recovery of nerve function after injury is not completely satisfactory. Therefore, this experiment aimed to explore the effect and mechanism of combined application of melatonin and chondroitin sulfate ABC on nerve regeneration and functional recovery after nerve-root avulsion of the brachial plexus. Fifty-two Sprague-Dawley rats were selected and their C5-7 nerve roots were avulsed. Then, the C6 nerve roots were replanted to construct the brachial plexus nerve-root avulsion model. After successful modeling, the injured rats were randomly divided into four groups. The first group (injury) did not receive any drug treatment, but was treated with a pure gel-sponge carrier nerve-root implantation and an ethanol-saline solution via intraperitoneal (i.p.) injection. The second group (melatonin) was treated with melatonin via i.p. injection. The third group (chondroitin sulfate ABC) was treated with chondroitin sulfate ABC through local administration. The fourth group (melatonin + chondroitin sulfate ABC) was treated with melatonin through i.p. injection and chondroitin sulfate ABC through local administration. The upper limb Terzis grooming test was used 2-6 weeks after injury to evaluate motor function. Inflammation and oxidative damage within 24 hours of injury were evaluated by spectrophotometry. Immunofluorescence and neuroelectrophysiology were used to evaluate glial scar, neuronal protection, and nerve regeneration. The results showed that the Terzis grooming-test scores of the three groups that received treatment were better than those of the injury only group. Additionally, these three groups showed lower levels of C5-7 intramedullary peroxidase and malondialdehyde. Further, glial scar tissue in the C6 spinal segment was smaller and the number of motor neurons was greater. The endplate area of the biceps muscle was larger and the structure was clear. The latency of the compound potential of the myocutaneous nerve-biceps muscle was shorter. All these indexes were even greater in the melatonin + chondroitin sulfate ABC group than in the melatonin only or chondroitin sulfate ABC only groups. Thus, the results showed that melatonin combined with chondroitin sulfate ABC can promote nerve regeneration after nerve-root avulsion injury of the brachial plexus, which may be achieved by reducing oxidative damage and inflammatory reaction in the injury area and inhibiting glial scar formation.

Targeting STATs in neuroinflammation: The road less traveled!

JAK/STAT transduction pathway is a highly conserved pathway implicated in regulating cellular proliferation, differentiation, survival and apoptosis. Dysregulation of this pathway is involved in the onset of autoimmune, haematological, oncological, metabolic and neurological diseases. Over the last few years, the research of anti-neuroinflammatory agents has gained considerable attention. The ability to diminish the STAT-induced transcription of inflammatory genes is documented for both natural compounds (such as polyphenols) and chemical drugs. Among polyphenols, quercetin and curcumin directly inhibit STAT, while Berberis vulgaris L. and Sophora alopecuroides L extracts act indirectly. Also, the Food and Drug Administration has approved several JAK/STAT inhibitors (direct or indirect) for treating inflammatory diseases, indicating STAT can be considered as a therapeutic target for neuroinflammatory pathologies. Considering the encouraging data obtained so far, clinical trials are warranted to demonstrate the effectiveness and potential use in the clinical practice of STAT inhibitors to treat inflammation-associated neurodegenerative pathologies.

Andalucin from Artemisia lannta suppresses the neuroinflammation via the promotion of Nrf2-mediated HO-1 levels by blocking the p65-p300 interaction in LPS-activated BV2 microglia

BACKGROUND

Neuroinflammation plays an important role in many neurodegenerative conditions such as Alzheimer's disease (AD) and Parkinson disease (PD). Andalucin (ADL), a sesquiterpene lactone from Artemisia lannta, has been reported to exhibit NO inhibition in vitro. However, the effect of ADL on microglia-mediated neuroinflammation has not been investigated.

PURPOSE

This study was designed to determine the anti-neuroinflammatory effect of ADL against LPS-activated BV2 microglial cells and to explore the underlying mechanisms.

METHODS

The production of pro-inflammatory mediators and cytokines were measured by ELISA. The relevant mechanisms were analyzed by qRT-PCR, Luciferase assay, Western blot and Co-immunoprecipitation Assay.

RESULTS

ADL inhibited the LPS-induced release of NO, PGE₂, TNF-α, IL-6 and IL-1β. In addition, ADL reduced the mRNA and protein levels of iNOS and COX-2. Mechanism studies found that ADL activated Nrf2/HO-1 signaling pathway and suppressed NF-κB signaling pathway. Further investigation showed that the stimulative effect of ADL on Nrf2 transcriptional activity and the inhibitory effect of ADL on RelA transcriptional activity were due to its regulation on p300-Nrf2/p65 interaction.

CONCLUSION

ADL displayed anti-neuroinflammatory activity in LPS-activated BV2 cells. The mechanism concerns its regulatory effect on the crosstalk between Nrf2 and p65.

The small molecule CA140 inhibits the neuroinflammatory response in wild-type mice and a mouse model of AD

Background

Neuroinflammation is associated with neurodegenerative diseases, including Alzheimer’s disease (AD). Thus, modulating the neuroinflammatory response represents a potential therapeutic strategy for treating neurodegenerative diseases. Several recent studies have shown that dopamine (DA) and its receptors are expressed in immune cells and are involved in the neuroinflammatory response. Thus, we recently developed and synthesized a non-self-polymerizing analog of DA (CA140) and examined the effect of CA140 on neuroinflammation.

Methods

To determine the effects of CA140 on the neuroinflammatory response, BV2 microglial cells were pretreated with lipopolysaccharide (LPS, 1 μg/mL), followed by treatment with CA140 (10 μM) and analysis by reverse transcription-polymerase chain reaction (RT-PCR). To examine whether CA140 alters the neuroinflammatory response in vivo, wild-type mice were injected with both LPS (10 mg/kg, intraperitoneally (i.p.)) and CA140 (30 mg/kg, i.p.), and immunohistochemistry was performed. In addition, familial AD (5xFAD) mice were injected with CA140 or vehicle daily for 2 weeks and examined for microglial and astrocyte activation.

Results

Pre- or post-treatment with CA140 differentially regulated proinflammatory responses in LPS-stimulated microglia and astrocytes. Interestingly, CA140 regulated D1R levels to alter LPS-induced proinflammatory responses. CA140 significantly downregulated LPS-induced phosphorylation of ERK and STAT3 in BV2 microglia cells. In addition, CA140-injected wild-type mice exhibited significantly decreased LPS-induced microglial and astrocyte activation. Moreover, CA140-injected 5xFAD mice exhibited significantly reduced microglial and astrocyte activation.

Conclusions

CA140 may be beneficial for preventing and treating neuroinflammatory-related diseases, including AD.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1321-3) contains supplementary material, which is available to authorized users.

An Aqueous Extract of Herbal Medicine ALWPs Enhances Cognitive Performance and Inhibits LPS-Induced Neuroinflammation via FAK/NF-κB Signaling Pathways

Recent studies have shown that Liuwei Dihuang pills (LWPs) can positively affect learning, memory and neurogenesis. However, the underlying molecular mechanisms are not understood. In the present study, we developed ALWPs, a mixture of Antler and LWPs, and investigated whether ALWPs can affect neuroinflammatory responses. We found that ALWPs (500 mg/ml) inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine IL-1β mRNA levels in BV2 microglial cells but not primary astrocytes. ALWPs significantly reduced LPS-induced cell-surface levels of TLR4 to alter neuroinflammation. An examination of the molecular mechanisms by which ALWPs regulate the LPS-induced proinflammatory response revealed that ALWPs significantly downregulated LPS-induced levels of FAK phosphorylation, suggesting that ALWPs modulate FAK signaling to alter LPS-induced IL-1β levels. In addition, treatment with ALWPs followed by LPS resulted in decreased levels of the transcription factor NF-κB in the nucleus compared with LPS alone. Moreover, ALWPs significantly suppressed LPS-induced BV2 microglial cell migration. To examine whether ALWPs modulate learning and memory in vivo, wild-type C57BL/6J mice were orally administered ALWPs (200 mg/kg) or PBS daily for 3 days, intraperitoneally injected (i.p.) with LPS (250 μg/kg) or PBS, and assessed in Y maze and NOR tests. We observed that oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly rescued short- and long-term memory. More importantly, oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly reduced microglial activation in the hippocampus and cortex. Taken together, our results suggest that ALWPs can suppress neuroinflammation-associated cognitive deficits and that ALWPs have potential as a drug for neuroinflammation/neurodegeneration-related diseases, including Alzheimer's disease (AD).

Activation of Nrf2 signaling by salvianolic acid C attenuates NF‑κB mediated inflammatory response both in vivo and in vitro

Neurodegenerative diseases are closely related to neuroinflammation. Drugs targeting inflammation have been proved to be effective in many animal models. Salvianolic acid C (SalC) is a compound isolated from Salvia miltiorrhiza Bunge, a plant with reported effects of inhibiting inflammation. However, the anti-inflammation effects and biological mechanisms of SalC on LPS-stimulated neuroinflammation remain unknown. The aim of this paper was to study its protective effects and its anti-inflammation mechanisms. LPS was used both in vivo and in vitro to induce neuroinflammation in SD rats and microglia cells. MTT assay was carried out to detect cell viability. The levels of TNF‑α, IL‑1β, IL‑6, IL‑10 and PGE₂ were detected by ELISA method. The expressions of p‑AMPK, p‑NF‑κB p65, p‑IκBα, Nrf2, HO‑1 and NQO1 proteins were examined by Western blot analysis. The nuclear translocation of NF‑κB p65 was studied by immunofluorescence assay. The specific Nrf2 siRNA was used to clarify the interaction between Nrf2 and NF‑κB p65. The AMPK inhibitor Compound C was used study the upstream protein of Nrf2. Results showed that LPS induced the overexpression of inflammatory cytokines and mediated the phosphorylation and nuclear translocation of NF‑κB p65 in rat brains and microglia cells. SalC reversed the inflammatory response induced by LPS and inhibited the NF‑κB activation. SalC also upregulated the expression of p‑AMPK, Nrf2, HO‑1 and NQO1. But the anti-inflammation and NF‑κB inhibition effects of SalC were attenuated by transfection with specific Nrf2 siRNA or interference with the potent AMPK inhibitor Compound C. In conclusion, SalC inhibited LPS-induced inflammatory response and NF‑κB activation through the activation of AMPK/Nrf2 signaling both in vivo and in vitro.

Heme Oxygenase 1 in the Nervous System: Does It Favor Neuronal Cell Survival or Induce Neurodegeneration?

Heme oxygenase 1 (HO-1) up-regulation is recognized as a pivotal mechanism of cell adaptation to stress. Under control of different transcription factors but with a prominent role played by Nrf2, HO-1 induction is crucial also in nervous system response to damage. However, several lines of evidence have highlighted that HO-1 expression is associated to neuronal damage and neurodegeneration especially in Alzheimer’s and Parkinson’s diseases. In this review, we summarize the current literature regarding the role of HO-1 in nervous system pointing out different molecular mechanisms possibly responsible for HO-1 up-regulation in nervous system homeostasis and neurodegeneration.

Cytotoxic Compounds from the Seeds of Sophora alopecuroides

Chemical purification of the ethyl acetate extract from the seeds of Sophora alopecuroides yielded a new natural product, ethyl 2-(4-hydroxybenzyl) malic acid (1), along with 7 known compounds, methyl eucomate (2), eucomic acid (3), piscidic acid (4) and ethyl 2-(4-hydroxybenzyl) tartrate (5), butein-4'-O-β-D-glucopyranoside (6), iso-liquiritigenin (7), and butein (8). The structure of 1 was determined by spectroscopic analyses including extensive 1D (1H NMR, 13C NMR) and 2D NMR spectra (COSY, HSQC and HMBC) as well as MS data. All compounds were evaluated for their cytotoxic activities against hepato-cellular carcinoma (HCC) cell lines, HepG2 andHep3B. Compound 8 significantly inhibited the cancer cell growth in a concentration-dependent manner.

The Antidiabetic and Antinephritic Activities of Tuber melanosporum via Modulation of Nrf2-Mediated Oxidative Stress in the db/db Mouse

Tuber melanosporum (TM), a valuable edible fungus, contains 19 types of fatty acid, 17 types of amino acid, 6 vitamins, and 7 minerals. The antidiabetic and antinephritic effects of TM and the underlying mechanisms related to oxidative stress were investigated in db/db mice. Eight-week oral administration of metformin (Met) at 0.1 g/kg and TM at doses of 0.2 and 0.4 g/kg decreased body weight, plasma glucose, serum levels of glycated hemoglobin, triglyceride, and total cholesterol and increased serum levels of high-density lipoprotein cholesterol in the mice, suggesting hypoglycemic and hypolipidemic effects. TM promoted glucose metabolism by increasing the levels of pyruvate kinase and hepatic glycogen. It also regulated the levels of inflammatory factors and oxidative enzymes in serum and/or the kidneys of the mice. Additionally, TM increased the expression of nuclear respiratory factor 2 (Nrf2), catalase, heme oxygenase 1, heme oxygenase 2, and manganese superoxide dismutase 2 and decreased the expression of protein kinase C alpha, phosphor-janus kinase 2, phosphor-signal transducer and activator of transcription 3, and phosphor-nuclear factor-κB in the kidneys. The results of this study reveal the antidiabetic and antidiabetic nephritic properties of TM via modulating oxidative stress and inflammation-related cytokines through improving the Nrf2 signaling pathway.

Herbal Compounds Play a Role in Neuroprotection through the Inhibition of Microglial Activation

Since microglia possess both neuroprotective and neurotoxic potential, they play a crucial role in the central nervous system (CNS). Excessive microglial activation induces inflammation-mediated neuronal damage and degeneration. At present, numerous herbal compounds are able to suppress neurotoxicity via inhibiting microglial activation. Therefore, many researchers focus on pharmacological inhibitors of microglial activation to ameliorate neurodegenerative disorders. Further work should concentrate on the exploration of new herbal compounds, which characteristically inhibit microglial neurotoxicity, rather than modulating neuroprotection alone. In this review, we summarize these herbal compounds, which in the past several years have been shown to exert potential neuroprotective activity by inhibiting microglial activation. The therapeutic targets and pharmacological mechanisms of these compounds have also been discussed.

Anti-inflammatory activity of Khayandirobilide A from Khaya senegalensis via NF-κB, AP-1 and p38 MAPK/Nrf2/HO-1 signaling pathways in lipopolysaccharide-stimulated RAW 264.7 and BV-2 cells

BACKGROUND

Immunocytes-involved inflammation is considered to modulate the damage in various diseases. Herein, novel therapeutics suppressing over-activation of immunocytes could prove an effective strategy to prevent inflammation-related diseases.

PURPOSE

The objective of this study is to evaluate the anti-inflammatory activity of Khayandirobilide A (KLA), a new andirobin-type limonoid with modified furan ring isolated from the Khaya senegalensis (Desr.) A. Juss., and to explore its potential underlying mechanisms in LPS-stimulated inflammatory models.

METHODS

The structure of KLA was elucidated on the basis of 1D- and 2D-NMR spectroscopic data as well as HR-ESI-MS. As for its anti-inflammatory effect, the production of pro-inflammatory mediators and cytokines in LPS-stimulated RAW 264.7 and BV-2 cells were measured by Griess reagent, ELISA and qRT-PCR. The relevant proteins including nuclear factor κB (NF-κB), p-AKT, p-p38 and Nrf2/HO-1 were investigated by western blot. Nuclear localisations of NF-κB, activator protein-1 (AP-1) and Nrf2 were also examined by western blot and immunofluorescence.

RESULTS

KLA could inhibit the production of LPS-induced NO with IC₅₀ values of 5.04 ± 0.14 µM and 4.97 ± 0.5 µM in RAW 264.7 and BV-2 cells, respectively. KLA also attenuated interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein and mRNA levels. Further mechanistic studies demonstrated the activation of NF-κB and AP-1 were reduced by KLA. Moreover, KLA elevated expression of heme oxygenase-1(HO-1) via inducing Keap1 autophagic degradation and promoting Nrf2 nuclear translocation. Despite KLA induced the phosphorylation of mitogen-activated protein kinases (MAPKs) family, inhibiting the phosphorylation of p38 by its specific inhibitor SB203580 attenuated the degradation of KLA-induced Keap1, and then reduced KLA-induced Nrf2 nuclear translocation and HO-1 expression. Furthermore, SB203580, Brusatol (a Nrf2 specific inhibitor) and ZnPP (a HO-1 specific inhibitor) could partly reverse the suppressive effects of KLA on LPS-induced NO production and mRNA levels of pro-inflammatory genes.

CONCLUSION

These data displayed that KLA possessed anti-inflammatory activity, which was attributed to inhibit the release of LPS-stimulated inflammatory mediators via suppressing the activation of NF-κB, AP-1, and upregulating the induction of p38 MAPK/Nrf2-mediated HO-1.

The effects of lead exposure on the expression of HMGB1 and HO-1 in rats and PC12 cells

Lead (Pb) is an environmental neurotoxic metal. Chronic exposure to Pb causes deficits of learning and memory in children and spatial learning deficits in developing rats. In this study we investigated the effects of Pb exposure on the expression of HMGB1 and HO-1 in rats and PC12 cells. The animals were randomly divided to three groups: control group; low lead exposure group; high lead exposure group; PC12 cells were divided into 3 groups: 0 μM (control group), 1 μM and 100 μM Pb acetate. The results showed that Pb levels in blood and brain of Pb exposed groups were significantly higher than that of the control group (p < 0.05). The expression of HMGB1 and HO-1 were increased in Pb exposed groups than that of the control group (p < 0.05). Moreover, we found that the up-regulation of HO-1 in Pb exposure environment inhibited the expression of HMGB1.

Steppogenin Isolated from Cudrania tricuspidata Shows Antineuroinflammatory Effects via NF-κB and MAPK Pathways in LPS-Stimulated BV2 and Primary Rat Microglial Cells

Excessive microglial stimulation has been recognized in several neurodegenerative diseases, including Parkinson’s disease (PD), Alzheimer’s disease (AD), amyotropic lateral sclerosis (ALS), HIV-associated dementia (HAD), multiple sclerosis (MS), and stroke. When microglia are stimulated, they produce proinflammatory mediators and cytokines, including nitric oxide (NO) derived from inducible NO synthase (iNOS), prostaglandin E2 (PGE₂) derived from cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-12 (IL-12), and interleukin-6 (IL-6). These inflammatory reactions are related to the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Therefore, the modulation of NF-κB and MAPK is vital to prevent microglial activation and confer resistance against neuronal injury. In this study, steppogenin (1) isolated from Cudrania tricuspidata suppressed the neuroinflammatory responses to lipopolysaccharide (LPS). Steppogenin (1) inhibited the production of proinflammatory mediators and cytokines in LPS-challenged BV2 and rat primary microglial cells. Moreover, western blot analysis and immunofluorescence revealed that the nuclear translocation of NF-κB was inhibited in LPS-induced BV2 and rat primary microglial cells. The LPS-stimulated activation of BV2 and rat primary microglial cells was inhibited by steppogenin (1) through the suppression of c-Jun NH2-terminal kinase (JNK) and p38 MAPK signaling. These results suggested that steppogenin (1) exerted antineuroinflammatory effects against acute neuroinflammation in BV2 and rat primary microglial cells by suppressing the activation of NF-κB and MAPK signaling and the production of proinflammatory mediators and cytokines.

Isoastragaloside I inhibits NF-κB activation and inflammatory responses in BV-2 microglial cells stimulated with lipopolysaccharide

The excessive activation of microglia in many neurodegenerative diseases is detrimental to neuronal survival. Isoastragaloside I (ISO I) is a natural saponin molecule found within the roots of Astragalus membranaceus, a famous traditional Chinese medicine. In the present study, the anti‑inflammatory effects and the mechanisms of action of ISO I on activated BV-2 cells stimulated with lipopolysaccharide (LPS) were investigated. ISO I dose‑dependently inhibited the excessive release of nitric oxide (NO) and tumor necrosis factor (TNF)-α in the LPS-stimulated BV-2 cells. Moreover, it decreased the production of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), and mitigated the gene expression of interleukin (IL)-1β, TNF-α and iNOS induced by LPS. Further experiments revealed that ISO I decreased the phosphorylation levels of nuclear factor-κB (NF-κB), and suppressed its nuclear translocation and transactivation activity. In addition, it inhibited the activation of signaling pathway molecules, such as PI3K, Akt and mitogen-activated protein kinases (MAPKs). Taken together, our findings suggest that ISO I prevents LPS-induced microglial activation probably by inhibiting the activation of the NF-κB via PI3K/Akt and MAPK signaling pathways, indicating its therapeutic potential for neurological diseases relevant to neuroinflammation.

Anti-inflammatory effects of flavonoids in neurodegenerative disorders

Neuroinflammation is one of the main mechanisms involved in the progression of several neurodegenerative diseases, such as Parkinson, Alzheimer, multiple sclerosis, amyotrophic lateral sclerosis and others. The activation of microglia is the main feature of neuroinflammation, promoting the release of pro-inflammatory cytokines and resulting in the progressive neuronal cell death. Natural compounds, such as flavonoids, possess neuroprotective potential probably related to their ability to modulate the inflammatory responses involved in neurodegenerative diseases. In fact, pure flavonoids (e.g., quercetin, genistein, hesperetin, epigallocatechin-3-gallate) or enriched-extracts, can reduce the expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β and COX-2), down-regulate inflammatory markers and prevent neural damage. This anti-inflammatory activity is primarily related to the regulation of microglial cells, mediated by their effects on MAPKs and NF-κB signalling pathways, as demonstrated by in vivo and in vitro data. The present work reviews the role of inflammation in neurodegenerative diseases, highlighting the potential therapeutic effects of flavonoids as a promising approach to develop innovative neuroprotective strategy.