Atsttrin reduces lipopolysaccharide-induced neuroinflammation by inhibiting the nuclear factor kappa B signaling pathway

Progranulin is closely related to neuronal survival in a neuroinflammatory mouse model and attenuates inflammatory reactions. Atsttrin is an engineered protein composed of three progranulin fragments and has been shown to have an effect similar to that of progranulin. Atsttrin has anti-inflammatory actions in multiple arthritis mouse models, and it protects against further arthritis development. However, whether Atsttrin has a role in neuroinflammation remains to be elucidated. In this study, we produced a neuroinflammatory mouse model by intracerebroventricular injection of 1 μL lipopolysaccharide(10 μg/μL). Atsttrin(2.5 mg/kg) was administered via intraperitoneal injection every 3 days over a period of 7 days before intracerebroventricular injection of 1 μL lipopolysaccharide(10 μg/μL). In addition, astrocyte cultures were treated with 0, 100 or 300 ng/mL lipopolysaccharide, with 200 ng/mL Atsttrin simultaneously. Immunohistochemistry, enzyme-linked immunosorbent assay and real-time reverse transcription-polymerase chain reaction were performed to examine the protein and mRNA levels of inflammatory mediators and to assess activation of the nuclear factor kappa B signaling pathway. Progranulin expression in the brain of wild-type mice and in astrocyte cultures was increased after lipopolysaccharide administration. The protein and mRNA expression levels of tumor necrosis factor-α, interleukin-1β and inducible nitric oxide synthase were increased in the brain of progranulin knockout mice after lipopolysaccharide administration. Atsttrin treatment reduced the lipopolysaccharide-induced increase in the protein and mRNA levels of tumor necrosis factor-α, interleukin-1β, matrix metalloproteinase-3 and inducible nitric oxide synthase in the brain of progranulin knockout mice. Atsttrin also reduced the expression of cyclooxygenase-2, inducible nitric oxide synthase and matrix metalloproteinase 3 mRNA in lipopolysaccharide-treated astrocytes in vitro, and decreased the concentration of tumor necrosis factor α and interleukin-1β in the supernatant. Furthermore, Atsttrin significantly reduced the levels of phospho-nuclear factor kappa B inhibitor α in the brain of lipopolysaccharide-treated progranulin knockout mice and astrocytes, and it decreased the expression of nuclear factor kappa B2 in astrocytes. Collectively, our findings show that the anti-neuroinflammatory effect of Atsttrin involves inhibiton of the nuclear factor kappa B signaling pathway, and they suggest that Atsttrin may have clinical potential in neuroinflammatory therapy.

Acacetin protects against cerebral ischemia-reperfusion injury via the NLRP3 signaling pathway

Acacetin(5,7-dihydroxy-4′-methoxyflavone), a potential neuroprotective agent, has an inhibitory effect on lipopolysaccharide-induced neuroinflammatory reactions. However, whether acacetin has an effect on inflammatory corpuscle 3(NLRP3) after cerebral ischemia-reperfusion injury has not been fully determined. This study used an improved suture method to establish a cerebral ischemia-reperfusion injury model in C57BL/6 mice. After ischemia with middle cerebral artery occlusion for 1 hour, reperfusion with intraperitoneal injection of 25 mg/kg of acacetin(acacetin group) or an equal volume of saline(0.1 mL/10 g, middle cerebral artery occlusion group) was used to investigate the effect of acacetin on cerebral ischemia-reperfusion injury. Infarct volume and neurological function scores were determined by 2,3,5-triphenyltetrazolium chloride staining and the Zea-Longa scoring method. Compared with the middle cerebral artery occlusion group, neurological function scores and cerebral infarction volumes were significantly reduced in the acacetin group. To understand the effect of acacetin on microglia-mediated inflammatory response after cerebral ischemia-reperfusion injury, immunohistochemistry for the microglia marker calcium adapter protein ionized calcium-binding adaptor molecule 1(Iba1) was examined in the hippocampus of ischemic brain tissue. In addition, tumor necrosis factor-α, interleukin-1β, and interleukin-6 expression in ischemic brain tissue of mice was quantified by enzyme-linked immunosorbent assay. Expression of Iba1, tumor necrosis factor-α, interleukin-1β and interleukin-6 was significantly lower in the acacetin group compared with the middle cerebral artery occlusion group. Western blot assay results showed that expression of Toll-like receptor 4, nuclear factor kappa B, NLRP3, procaspase-1, caspase-1, pro-interleukin-1β, and interleukin-1β were significantly lower in the acacetin group compared with the middle cerebral artery occlusion group. Our findings indicate that acacetin has a protective effect on cerebral ischemia-reperfusion injury, and its mechanism of action is associated with inhibition of microglia-mediated inflammation and the NLRP3 signaling pathway.

Puerarin partly counteracts the inflammatory response after cerebral ischemia/reperfusion via activating the cholinergic anti-inflammatory pathway

Puerarin, a major isoflavonoid derived from the Chinese medical herb radix puerariae （Gegen）, has been reported to inhibit neuronal apoptosis and play an anti-inflammatory role in focal cerebral ischemia model rats. Recent findings regarding stroke pathophysiology have recognized that anti-inflammation is an important target for the treatment of ischemic stroke. The cholinergic anti-inflammatory pathway is a highly robust neural-immune mechanism for inflammation control. This study was to investigate whether activating the cholinergic anti-inflammatory pathway can be involved in the mechanism of inhibiting the inflammatory response during puerarin-induced cerebral ischemia/reperfusion in rats. Results showed that puerarin pretreatment （intravenous injection） re- duced the ischemic infarct volume, improved neurological deficit after cerebral ischemia/reperfusion and decreased the levels of interleukin-1β, interleukin-6 and tumor necrosis factor-a in brain tissue. Pretreatment with puerarin （intravenous injection） attenuated the inflammatory response in rats, which was accompanied by janus-activated kinase 2 （JAK2） and signal transducers and activators of transcription 3 （STAT3） activation and nuclear factor kappa B （NF-KB） inhibition. These observa- tions were inhibited by the alpha7 nicotinic acetylcholine receptor （a7nAchR） antagonist a-bungarotoxin （a-BGT）. In addition, puerarin pretreatment increased the expression of a7nAchR mRNA in ischemic cerebral tissue. These data demonstrate that puerarin pretreatment strongly protects the brain against cerebral ischemia/reperfusion injury and inhibits the inflammatory re- sponse. Our results also indicated that the anti-inflammatory effect of puerarin may partly be medi- ated through the activation of the cholinergic anti-inflammatory pathway.

The Regulatory Effects of Polyporus Polysaccharide on the Nuclear Factor Kappa B Signal Pathway of Bladder Cancer Cells Stimulated by Bacillus Calmette-Guerin

Objective：To detect the effects of Polyporus polysaccharide（PPS）,Bacillus Calmette-Guerin （BCG）,and their combination on the nuclear factor kappa B（NF-κB）signaling pathway associated-gene expression and investigate the molecular mechanisms of the toxic-reducing effect of PPS in coordination with BCG against bladder cancer.Methods：After T739 cells were treated with PPS,BCG and their combination, the changes in mRNA and protein expression of inhibitor of kappa B kinase beta（IKKβ）,NF-κB subunit p65 （NF-κB p65）,intracellular adhesion molecule 1（ICAM1）and chemokine（C-c motif）ligand 2（CCL2）in bladder cancer cell line T739 were determined by relative quantitative real-time PCR,Western blot,and flow cytometry （FCM）.NF-κB p65 DNA-binding activity in T739 cell was detected by biotinylated probe-ELISA,and NF-κB p65 nuclear expression in T739 cell was observed by immunohistochemistry.Results：Compared with the T739 control group,the mRNA expression of IKBKB（IKKβ）,Rel A（NF-κB p65）,ICAM1 and CCL2 in T739 cells treated with BCG were increased obviously（Ratio2.0）,as well as the expression of IKKβ,CCL2 and ICAM1 proteins.Meanwhile,NF-κB p65 DNA-binding activity and NF-κB p65 nuclear expression in T739 cells treated with BCG were up-regulated significantly（P0.05）.Compared with the control,the increased expression in T739 cells were simultaneously down-regulated after PPS treatment,except for ICAM1 protein expression.With cells treated with a combination of BCG and PPS,the expression of genes associated with the NF-κB signaling pathway,such as IKBKB,ICAM1 and CCL2,were all down-regulated compared to the BCG group,as well as Rel A mRNA expression,NF-κB p65 DNA-binding activity and NF-κB p65 nuclear expression.Conclusions： PPS could inhibit the over-activation of the NF-κB signaling pathway induced by BCG in bladder cancer cells and accordingly attenuate the adverse reactions to BCG therapy.

Advances in NF-κB Signaling Transduction and Transcription

The molecular mechanisms for NF-κB signaling transduction and transcription have been the most attractive subjects for both basic research and pharmaceutical industries due to its important roles in both physiological and pathogenesis,particularly the close association of dysregulated NF-κB with tumorgenesis and inflammation.Several novel intracellular molecular events that regulate NF-κB activity have been described recently,including the discovery of an alternative signaling pathway that appears inducing a specific subset genes involved in adoptive immune response.Multi-level and multi-dimensional regulation of NF-κB activity by phosphorylation and acetylation modifications have unveiled and became the hottest targets for potentially tissue specific molecular interventions.Another emerging mechanism for NF-κB-responsive gene's regulation where NF-κB participates the transcriptional regulation independent of its cognate regulatory binding site within the target gene's promoter but facilitating the transaction activity of other involved transcription factors, that implicated an novel transcriptional activities for NF-κB.Thus,the current review will focus on these recent progresses that have been made on NF-κB signaling transduction and transcription.Cellular & Molecular Immunology.2004;1(6):425-435.

Splicing factor SF3B3,a NS5-binding protein,restricts ZIKV infection by targeting GCH1

Zika virus(ZIKV),a positive-sense single-stranded RNA virus,causes congenital ZIKV syndrome in children and Guillain-Barre Syndrome(GBS)in adults.ZIKV expresses nonstructural protein 5(NS5),a large protein that is essential for viral replication.ZIKV NS5 confers the ability to evade interferon(IFN)signalling;however,the exact mechanism remains unclear.In this study,we employed affinity pull-down and liquid chromatography-tandem mass spectrometry(LC-MS/MS)analyses and found that splicing factor 3b subunit 3(SF3B3)is associated with the NS5-Flag pull-down complex through interaction with NS5.Functional assays showed that SF3B3 overexpression inhibited ZIKV replication by promoting IFN-stimulated gene(ISG)expression whereas silencing of SF3B3 inhibited expression of ISGs to promote ZIKV replication.GTP cyclohydrolase I(GCH1)is the first and ratelimiting enzyme in tetrahydrobiopterin(BH4)biosynthesis.NS5 upregulates the expression of GCH1 during ZIKV infection.And GCH1 marginally promoted ZIKV replication via the IFN pathway.Additionally,GCH1 expression is related to the regulation of SF3B3.Overexpression of the SF3B3 protein effectively reduced GCH1 protein levels,whereas SF3B3 knockdown increased its levels.These findings indicated that ZIKV NS5 binding protein SF3B3 contributed to the host immune response against ZIKV replication by modulating the expression of GCH1.

NF-κB,a hot topic in biochemical and medical studies in China

In 1986, nuclear factor (NF)-κB was first discovered in the laboratory of Nobel Prize laureate David Baltimore via its interaction with a sequence (5′-GGGACTTTCC-3′) in the immunoglobulin light-chain enhancer in B

Protective Effect of Total Alkaloids of Sophora Alopecuroides on Dextran Sulfate Sodium-Induced Chronic Colitis

Objective：To investigate the effect of total alkaloids of Sophora alopecuroides（TASA） on dextran sulfate sodium（DSS）-induced colitis in mice.Methods：Chronic experimental colitis was induced by administration of 4 cycles of 4%DSS.Fifty mice were randomly distributed into 4 groups（normal,DSS,DSS/high-dose TASA, and DSS/low-dose TASA groups） by a random number table with body weight stratification.Mice in the normal group（n=11） and DSS-induced colitis control group（n=15） received control treatment of 20 mL/kg distilled water; DSS plus TASA high- and low-dose groups（n=12 each） were treated with TASA solution（20 mL/kg） at the doses of 60 mg/kg and 30 mg/kg,respectively.The severity of colitis was assessed on the basis of clinical signs, colon length,and histology scores.Moreover,secretory immunoglobulin A（slgA） and haptoglobin（HP） were analyzed by enzyme linked immunosorbent assay;intercellular adhesion molecule 1（ICAM-1） and macrophage-migration inhibitory factor（MIF） gene expressions were analyzed by quantitative reverse transcriptase realtime polymerase chain reaction（qRT-PCR） using SYBA greenⅠ;and nuclear factorκB（NF-κB） expression and activation and p65 interaction with the promoter of ICAM-1 gene were assessed by Western blotting and chromatin immunoprecipitation assay.Results：TASA administration significantly attenuated the damage and substantially reduced HP elevation and maintained the level of cecum slgA.TASA inhibited the ICAM-1 gene expression and had no effect on MIF gene expression.Also,TASA was able to reduce phospho-lκBα（p-lκBα） protein expression;however,it had no effect on the activation of IκB kinaseα（IKKα） and inhibitor of NF-κBα（IκBα）.Moreover,TASA inhibited the p65 recruitment to the ICAM-1 gene promoter.Conclusions：TASA had a protective effect on DSS-induced colitis.Such effect may be associated with its inhibition of NF-κB activation and blockade of NF-κB-regulated transcription activation of proinflammatory mediator gene.