研究: 肺炎衣原体抑制LXRα-ABCA1途径促进巨噬细胞脂质蓄积

为探讨肝X受体α (LXRα)-三磷酸腺苷结合盒转运体A1 (ABCA1)途径在肺炎衣原体 (C. pneumoniae)促巨噬细胞脂质蓄积中的作用和机制,以THP-1巨噬细胞源性泡沫细胞为模型,采用高效液相色谱分析细胞内总胆固醇、游离胆固醇和胆固醇酯含量,液体闪烁计数器检测细胞内胆固醇流出,RT-PCR检测ABCA1和LXRα mRNA的表达,蛋白质印迹检测ABCA1和LXRα的蛋白质表达;使用LXRα的特异性激动剂T0901317对细胞进行预处理,再观察上述指标的变化．结果显示,C. pneumoniae可促进THP-1巨噬细胞源性泡沫细胞内总胆固醇、游离胆固醇和胆固醇酯含量增加,抑制胆固醇外流,降低细胞ABCA1和LXRα的表达;使用ABCA1激动剂8-溴-环磷酸腺苷预处理细胞或LXR激动剂T0901317预处理细胞后,可明显减弱C. pneumoniae对THP-1细胞ABCA1的表达抑制,促进细胞胆固醇流出,降低细胞内胆固醇的含量．结果提示,C. pneumoniae促进巨噬细胞脂质蓄积及胆固醇流出障碍,其机制可能与LXRα-ABCA1途径有关．     

异氟醚通过Nrf2/HO-1/ROS途径抑制缺氧引起肺动脉平滑肌细胞焦亡

研究发现,异氟醚吸入麻醉可明显减轻由缺血-再灌注引起的肺动脉高压(PAH),提示其对肺循环功能有一定保护效应。肺动脉平滑肌细胞(PASMC)是肺动脉血管重塑和PAH发生的主要参与者,其结构改变和功能异常均可显著影响肺动脉高压病情进展。本研究探讨异氟醚对缺氧诱导的PASMC焦亡的影响及其调控机制,旨在为肺动脉高压治疗提供潜在分子靶点。PASMC于37℃、5%CO₂、3%O₂条件下静置培养24 h建立缺氧模型。RT-PCR和Western印迹等结果显示,缺氧致使PASMC内紅系衍生的核转录因子2(Nrf2)核转位减少,血红素加氧酶-1(HO-1)表达水平下调,而焦亡相关蛋白质,包括NOD样受体蛋白3(NLRP3)、胱天蛋白酶1(caspase-1)、凋亡相关斑点样蛋白(ASC)及消皮素D(GSDMD)等表达上调,活性氧(ROS)生成、胱天蛋白酶1活性和乳酸脱氢酶(LDH)释放水平升高,Hoechst/PI染色显示,焦亡孔洞增加。ELISA结果表明,IL-1β、IL-6、IL-18和TNF-α分泌增加(P<0.05)。异氟醚处理可显著激活Nr...     

TNFα诱导激活NF-κB上调抑癌基因CDKN2B表达

NF-κB通过转录调控其靶基因,在肿瘤发生发展和精准治疗中起关键作用。过表达抑癌基因细胞周期蛋白依赖性激酶抑制剂2B（CDKN2B）可抑制肿瘤细胞增殖并诱导凋亡,但是否受NF-κB调节尚无报道。本文发现,NF-κB直接结合并上调CDKN2B基因：在TNFα处理的HeLa细胞内,CDKN2B的基因区覆盖大量NF-κB结合峰,其中富集倍数大于20的结合峰有14个。TRANSFAC软件分析发现,NF-κB结合峰内包含大量经典的κB位点。ChIP-qPCR证明,TNFα诱导NF-κB结合CDKN2B基因。将NF-κB结合峰中心区DNA片段插入荧光素酶报告基因载体中,发现该DNA片段的插入使荧光素酶相对活性上调至7.88倍,TNFα处理又使其相对活性提高到2.37倍,且NF-κB/p65 siRNA显著干扰其相对活性的升高。免疫荧光检测显示,TNFα诱导激活NF-κB进入细胞核,而NF-κB/p65 siRNA阻止它入核。此结果提示,我们成功构建了具有NF-κB转录活性差异的细胞模型,qPCR检测两个已知的NF-κB靶基因NFKB2和STAT5A的表达,进一步验证该细胞模型构建成功。利用此细胞模型,发现受TNFα诱导激活的NF-κB,能够上调CDKN2B基因。总之,本文发现抑癌基因CDKN2B是NF-κB新的靶基因,NF-κB直接结合并上调CDKN2B基因在转录水平的表达。本研究为抑癌基因CDKN2B的抗肿瘤应用奠定了基础。     

Chrysophanol Suppresses Cell Growth via mTOR/PPAR-α Regulation and ROS Accumulation in Cultured Human Tongue Squamous Carcinoma SAS Cells

Oral cancer, a type of head and neck cancer, can pose a significant risk of death unless diagnosed and treated early. Alternative treatments are urgently needed owing to the high mortality rate, limitations of conventional treatments, and many complications. The anthraquinone compound chrysophanol acts as a tumor suppressor on some types of cancer cells. To date, it has not been clarified how chrysophanol affects human tongue squamous carcinoma. This study was aimed to examine the effects of chrysophanol on oral cancer treatment. The results show that chrysophanol caused cell death, reduced the expression of the mammalian target of rapamycin (mTOR)/peroxisome proliferator-activated receptor-alpha (PPAR-α), and increased reactive oxygen species (ROS) production. We also used two ion chelators, deferoxamine (DFO) and liproxstatin-1 (Lipro), to further determine whether chrysophanol inhibits cell growth and regulates mTOR/PPAR-α expression and ROS production, both of which are involved in iron homeostasis. The results show that DFO and Lipro reversed the increase in cell death, downregulation of mTOR/PPAR-α, and decrease in ROS accumulation. In conclusion, chrysophanol inhibits the growth of oral squamous cell carcinoma cells by modulating mTOR/PPAR-α and by causing ROS accumulation.     

LL202 ameliorates colitis against oxidative stress of macrophage by activation of the Nrf2/HO-1 pathway

LL202, a newly synthesized flavonoid derivative, has been confirmed to inhibit the mitogen-activated protein kinase pathway and activation protein-1 activation in monocytes; however, the anti-inflammatory mechanism has not been clearly studied. Uncontrolled overproduction of reactive oxygen species (ROS) has involved in oxidative damage of inflammatory bowel disease. In this study, we investigated that LL202 reduced lipopolysaccharide (LPS)-induced ROS production and malondialdehyde levels and increased superoxide dismutase, glutathione, and total antioxidant capacity in RAW264.7 cells. Mechanically, LL202 could upregulate heme oxygenase-1 (HO-1) via promoting nuclear translocation of nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) to regulate LPS-induced oxidative stress in macrophages. In vivo, we validated the role of LL202 in dextran sulfate sodium- and TNBS-induced colitis models, respectively. The results showed that LL202 decreased the proinflammatory cytokine expression and regulated colonic oxidative stress by activating the Nrf2/HO-1 pathway. In conclusion, our study showed that LL202 exerts an anti-inflammatory effect by enhancing the antioxidant capacity of the Nrf2/HO-1 pathway to macrophages.     

Modulation of Nrf2 expression alters high glucose-induced oxidative stress and antioxidant gene expression in mouse mesangial cells

Reactive oxygen species (ROS) play an important role in the pathogenesis of diabetic nephropathy. Nuclear factor erythroid 2-related factor 2 (Nrf2) can up-regulate the expression of antioxidant genes and protect cells from oxidative damage. The current study is aimed at examining the effect of modulation of Nrf2 expression on high glucose-induced oxidative stress and Nrf2-targeting antioxidant expression in mouse mesangial cells. In this study, mouse mesangial cells were transiently transfected with Nrf2-plasmid or the Nrf2-specific siRNA. The high glucose-induced intracellular ROS, malondialdehyde, cell proliferation, and TGF-β1 secretion were measured. The levels of Nrf2, heme oxygenase-1 (HO-1), γ-glutamylcysteine synthethase (γ-GCS) expression, and nuclear expression of Nrf2 in mouse mesangial cells were determined. We found that high glucose induced ROS and malondialdehyde generation in mouse mesangial cells. Induction of Nrf2 over-expression reduced the high glucose-induced ROS and malondialdehyde production, inhibited cell proliferation and TGF-β1 secretion, accompanied by up-regulating the expressions of HO-1 and γ-GCS in mouse mesangial cells. However, knockdown of Nrf2 expression displayed reverse effects in mouse mesangial cells. All these results indicated that Nrf2 and its downstream antioxidants, HO-1 and γ-GCS, are negative regulators of high glucose-induced ROS-related mouse mesangial cell dysfunction.     

Phase II enzyme induction by a carotenoid,lutein, in a PC12D neuronal cell line

The mechanism by which lutein, a carotenoid, acts as an antioxidant in retinal cells is still not fully understood. Here, lutein treatment of a neuronal cell line (PC12D) immediately resulted in reduced intracellular ROS levels, implying that it has a direct role in ROS scavenging. Significantly, lutein treatment also induced phase II antioxidative enzyme expression, probably via a nuclear factor-like 2 (Nrf2) independent pathway. This latter mechanism could explain why lutein acts diversely to protect against oxidative/cytotoxic stress, and why it is physiologically involved in the human neural tissue, such as the retina.     

Helvolic acid attenuates osteoclast formation and function via suppressing RANKL-induced NFATc1 activation

Excessive osteoclast formation and function are considered as the main causes of bone lytic disorders such as osteoporosis and osteolysis. Therefore, the osteoclast is a potential therapeutic target for the treatment of osteoporosis or other osteoclast-related diseases. Helvolic acid (HA), a mycotoxin originally isolated from Aspergillus fumigatus , has been discovered as an effective broad-spectrum antibacterial agent and has a wide range of pharmacological properties. Herein, for the first time, HA was demonstrated to be capable of significantly inhibiting receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption in vitro by suppressing nuclear factor of activated T cells 1 (NFATc1) activation. This inhibition was followed by the dramatically decreased expression of NFATc1-targeted genes including Ctr (encoding calcitonin receptor), Acp5 (encoding tartrate-resistant acid phosphatase [TRAcP]), Ctsk (encoding cathepsin K), Atp6v0d2 (encoding the vacuolar H+ ATPase V0 subunit d2 [V-ATPase-d2]) and Mmp9 (encoding matrix metallopeptidase 9) which are osteoclastic-specific genes required for osteoclast formation and function. Mechanistically, HA was shown to greatly attenuate multiple upstream pathways including extracellular signal-regulated kinase (ERK) phosphorylation, c-Fos signaling, and intracellular Ca ²⁺ oscillation, but had little effect on nuclear factor-κB (NF-κB) activation. In addition, HA also diminished the RANKL-induced generation of intracellular reactive oxygen species. Taken together, our study indicated HA effectively suppressed RANKL-induced osteoclast formation and function. Thus, we propose that HA can be potentially used in the development of a novel drug for osteoclast-related bone diseases.     

Photoprotective Potential of Penta-O-Galloyl-β-DGlucose by Targeting NF-κB and MAPK Signaling in UVB Radiation-Induced Human Dermal Fibroblasts and Mouse Skin

Exposure of the skin to ultraviolet radiation can cause skin damage with various pathological changes including inflammation. In the present study, we identified the skin-protective activity of 1,2,3,4,6-penta-O-galloyl-β-D-glucose (pentagalloyl glucose, PGG) in ultraviolet B (UVB) radiation-induced human dermal fibroblasts and mouse skin. PGG exhibited antioxidant activity with regard to intracellular reactive oxygen species (ROS) generation as well as ROS and reactive nitrogen species (RNS) scavenging. Furthermore, PGG exhibited anti-inflammatory activity, inhibiting the activation of nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling, resulting in inhibition of the expression of pro-inflammatory mediators. Topical application of PGG followed by chronic exposure to UVB radiation in the dorsal skin of hairless mice resulted in a significant decrease in the progression of inflammatory skin damages, leading to inhibited activation of NF-κB signaling and expression of pro-inflammatory mediators. The present study demonstrated that PGG protected from skin damage induced by UVB radiation, and thus, may be a potential candidate for the prevention of environmental stimuli-induced inflammatory skin damage.     

白藜芦醇通过促进SIRT1表达，抑制NF-κB和TNF-α表达抵抗牛磺胆酸诱导的胎盘合体滋养细胞HTR-8的炎症损伤

摘要 已有研究证明,沉默信息调节子1(silent information regulator , SIRT1）和核因子κB(nuclear factor-κB, NF-κB）参与多种炎性反应调节;SIRT1激活剂——白藜芦醇（resveratrol）可通过依赖或不依赖于SIRT1的途径抑制炎症反应。然而,SIRT1及白藜芦醇在妊娠期肝内胆汁瘀积症（intrahepatic cholestasis of pregnancy, ICP）炎性反应中的作用在国内外尚未见报道。本研究证明,白藜芦醇可通过上调SIRT1表达,下调NF-κB及肿瘤坏死因子α（tumor necrosis factor-alpha, TNF-α）表达保护牛磺胆酸 （taurocholic acid, TCA）引起的胎盘合体滋养细胞HTR-8炎性损伤。免疫组化及Western印迹显示,SIRT1蛋白在正常胎盘组织的表达水平明显高于妊娠期ICP胎盘组织,而NF-κB蛋白表达在正常胎盘组织的表达低于ICP胎盘组织。Western印迹揭示,SIRT1蛋白在HTR-8细胞中的表达水平随暴露的TCA浓度增高而降低;相反,NF-κB和TNF-α蛋白质水平随TCA浓度增高而升高。采用白藜芦醇处理HTR-8细胞,该差异可被逆转;且白藜芦醇这一作用可被Ex-527（一种SIRT1 抑制剂）阻断。上述结果证明,在ICP胎盘合体滋养细胞炎性反应中SIRT1表达下调,而NF-κB表达上调;其可能的机制是ICP高浓度胆汁酸干扰胎盘合体滋养细胞SIRT1-NF-κB通路,诱导炎症反应。上述结果还提示,SIRT1激动剂——白藜芦醇可通过诱导SIRT1表达,抑制NF-κB及TNF-α表达,保护牛磺胆酸诱导的胎盘合体滋养细胞的炎性损伤。本研究为白藜芦醇临床治疗（妊娠期）肝内胆汁瘀积症提供了新的证据。至于白藜芦醇是否可直接抑制NF-κB的表达还有待进一步探讨。     

The GR-gp78 Pathway is involved in Hepatic Lipid Accumulation Induced by Overexpression of 11β-HSD1

Glucocorticoids are essential participants in the regulation of lipid metabolism. On a tissue-specific level, glucocorticoid signal is controlled by 11β-Hydroxysteroid dehydrogenase 1 (11β-HSD1). Up-regulation of 11β-HSD1 expression during non-alcoholic fatty liver disease (NAFLD) has been previously shown, while 11β-HSD1 inhibition has been shown to reduce hepatic lipids in NAFLD, but the underlying mechanisms remain unclear. Here, in this study, we created in vitro cell culture and in vivo transgenic hepatocyte-specific 11β-HSD1 mouse models of NAFLD to determine the regulatory mechanisms of 11β-HSD1 during lipid metabolism dysfunction. We found that 11β-HSD1 overexpression activated glucocorticoid receptors and promoted their nuclear translocation, and then stimulating gp78. The induction of gp78 sharply reduced expression of Insig2, but not Insig1, which led to up-regulation of lipogenesis regulatory proteins including SREBP1, FAS, SCD1, and ACC1. Our results suggested that overexpression of 11β-HSD1 induced lipid accumulation, at least partially through the GR/gp78/Insig2/SREBP1 pathway, which may serve as a potential diagnostic and therapeutic target for treatment of NAFLD.     

A genome-wide expression profile and system-level integration of nuclear factor kappa B regulated genes reveals fundamental metabolic adaptations during cell growth and survival

A murine lung alveolar carcinoma cell line (WT-Line 1) and its equally tumorigenic but non-malignant derivative transduced with a dominant negative inhibitor of NF-kappaB (mI-kappaB-Line 1), were profiled on the Affymetrix 19000 gene array platform. Two differentially expressed gene clusters were identified and integrated into a functional model. The downregulation of anti-oxidant defenses, in mI-kappaB-Line 1 cells, correlates with high levels of reactive oxygen species (ROS) and ROS damage to cellular macromolecules while the upregulation of metabolic nuclear receptors correlates with an adaptive/survival response, which involves a shift in energy metabolism toward beta-oxidative respiration. Accordingly, mI-kappaB-Line 1 cells are markedly sensitized to pharmacologic inhibition of beta-oxidative respiration. These findings are indicative of compensatory changes that could undermine anti-cancer therapies targeting NF-kappaB.     

miR-21a-5p Promotes Inflammation following Traumatic Spinal Cord Injury through Upregulation of Neurotoxic Reactive Astrocyte (A1) Polarization by Inhibiting the CNTF/STAT3/Nkrf Pathway

Reactive astrocytes are implicated in traumatic spinal cord injury (TSCI). Interestingly, naïve astrocytes can easily transform into neurotoxic reactive astrocytes (A1s) with inflammatory stimulation. Previous studies demonstrated that microRNA(miR)-21a-5p was up-regulated in spinal cord tissue after TSCI; however, it is not clear whether this affected reactive astrocyte polarization. Here, we aim to detect the effects of miR-21a-5p on the induction of A1 formation and the underlying mechanisms. Our study found that the expression of miR-21a-5p was significantly increased while that of Cntfr α was decreased, since naïve astrocytes transformed into A1s 3 days post-TSCI; the binding site between miR-21a-5p and Cntfr α was further confirmed in astrocytes. After treatment with CNTF, the levels of A1 markers decreased while that of A2 increased. The expression of A1 markers significantly decreased with the downregulation of miR-21a-5p, while Cntfr α siRNA treatment caused the opposite both in vitro and in vivo. To summarize, miR-21a-5p/Cntfr α promotes A1 induction and might enhance the inflammatory process of TSCI; furthermore, we identified, for the first time, the effect and potential mechanism by which CNTF inhibits naïve astrocytes transformation into A1s. Collectively, our findings demonstrate that targeting miR-21a-5p represents a prospective therapy for promoting the recovery of TSCI.     

Methylseleninic acid activates Keap1/Nrf2 pathway via up-regulating miR-200a in human oesophageal squamous cell carcinoma cells

Oesophageal squamous cell carcinoma (ESCC) occurs at a very high rates in certain regions of China. There are increasing evidences demonstrating that selenium could act as a potential anti-oesophageal cancer agent, but the precise mechanisms involved are still not completely understood. Methylseleninic acid (MSA), as a potent second-generation selenium compound, is a promising chemopreventive agent. Previous studies demonstrated that the kelch-like ECH-associated protein 1 (Keap1)/nuclear factor E2-related factor 2 (Nrf2) system plays a critical role in cancer prevention, but little is known about its association with MSA in ESCC cells. In the present study, we observed that MSA treatment significantly down-regulated Keap1, induced nuclear accumulation of Nrf2 and enhance the antioxidant response element (ARE) promoter activity in ESCC cells. MSA could also significantly induce miR-200a expression and inhibit Keap1 directly. Antagomir-200a could attenuate MSA treatment-induced Keap1 down-regulation in ESCC cells. Moreover, MSA-induced miR-200a expression was dependent on the mediation of Krüpple-like factor 4 (KLF4). These results reaffirm the potential role of MSA as a chemopreventive agent via the regulation of KLF4/miR-200a/Keap1/Nrf2 axis in ESCC cells.