Interleukin-8 differentially modulates interleukin-4- and interleukin-2-induced human B cell growth

The effect of interleukin-8 (IL)-8 on human B cell growth, as determined by thymidine uptake and viable cell numbers was studied. IL-8 inhibited IL-4-induced growth of B cells costimulated with anti-μ antibodies (Ab) or Staphylococcus aureus Cowan strain I (SAC) in a dose-dependent fashion. In contrast, IL-8 did not inhibit IL-2-induced growth of B cells. The IL-8-mediated inhibition was specific, since it was blocked by anti-IL-8 mAb but not by control IgG1. Moreover, anti-tumor necrosis factor-α (anti-TNF-α) Ab blocked IL-8-mediated inhibition. On the other hand, TNF-α, but not other cytokines including IL-1β, IL-3, IL-5, IL-6, interferon-α (IFN-α) or IFN-γ, inhibited IL-4-mediated growth, and inhibition by TNF-α was blocked by anti-TNF-α Ab but not by control IgG. IL-4 had no effect on TNF-α binding by B cells while it decreased TNF-α production by B cells. IL-8 had no effect in binding of IL-4, IL-2 or TNF-α by B cells, however, it enhanced TNF-α production by B cells. These results indicate that IL-8 inhibited IL-4-induced human B cell growth by enhancement of endogenous TNF-α production.     

Immunophilin ligands prevent H2O2-induced apoptotic cell death by increasing glutathione levels in neuro 2A neuroblastoma cells

We examined the effects of FK506 and its non-immunosuppressive derivative, GPI1046, on H2O2-induced reduction of cell viability and apoptotic cell death in Neuro 2A cells. Our results suggest that the protective properties of GPI1046 against H2O2-induced reduction of cell viability are equipotent with those of FK506 and may be mediated by increased intracellular concentrations of glutathione (GSH). In addition, both FK506 and GPI1046 prevented apoptotic cell death in Neuro 2A cells, although the antiapoptotic effect of FK506 was somewhat stronger than that of GPI1046. These findings suggest that non-immunosuppressive immunophilin ligands such as GPI1046 might be potentially useful in treatment of neurodegenerative diseases without serious side effects such as immune deficiency.     

Nicotine switches the form of H(2)O(2)-induced cell death from apoptosis to necrosis in U937 cells

Cigarette smoking is a major risk factor for lung diseases and oral diseases. The present study examined the effect of nicotine on H(2)O(2)-induced apoptosis in U937 cells. In the presence of 1 microg/ml nicotine, cell viability was not affected, but the cells were unable to undergo H(2)O(2)-induced apoptosis and instead died as a result of necrosis. Nicotine reduced the intracellular level of ATP, which is an important determinant of the form of cell death. These results suggest that nicotine can alter the cell death pathway by reducing the level of intracellular ATP, and that this effect may contribute to cigarette smoke-induced tissue destruction.     

钙调神经磷酸酶抑制剂对过氧化氢诱导的干细胞凋亡的影响简

目的比较钙调神经磷酸酶（CAN）抑制剂FK-506和环孢菌素A（CsA）保护脂肪组织来源干细胞（AT-DSCs）抗凋亡作用及可能机制。方法采用过氧化氢（H2O2）[分浓度0（对照组）、50、100、200、300、400μmo/LH2O26组]体外诱导AT-DSCs凋亡模型．凋亡模型的评价采用磷脂酰丝氨酸结合蛋白-异硫氰酸荧光素（AnnexinV-FITC）／碘化丙啶（PI）双染流式细胞术和线粒体内跨膜电位测定法;观察AT-DSCs凋亡细胞形态;AT-DSCs细胞活性检测采用CCK-8试剂;细胞色素C的表达采用Westernblot分析。结果与对照组比较,引起细胞凋亡率最高的是浓度100μmol／LH20,（15．60％±8．50％±4．50％±0．88％;p〈0．01）;但CaN抑制剂FK-506（质量浓度1mg／mL）（9．8％±1．3％Vs17．0％±1．6％,P〈0．01）和CsA（质量浓度1mg／mL）（12．2％±1．2％Vs17．0％4±1．6％,P〈0．01）预处理后细胞凋亡率均明显下降,细胞存活率明显提高（P〈0．01）。Western blot结果显示．CaN抑制剂FK-506（质量浓度1mg／mL）和CsA（质量浓度1mg／mL）可完全抑制H2O2诱导的细胞色素C释放。结论CaN抑制剂能保护H2O2诱导的干细胞凋亡。可能机制是CaN抑制剂能抑制细胞凋亡,提高细胞存活率,下调细胞色素C的释放。     

Minocycline protects melanocytes against H2O2-induced cell death via JNK and p38 MAPK pathways

Vitiligo is an acquired and progressive disorder manifested by the selective destruction of melanocytes in the skin. An extremely high level of hydrogen peroxide (H2O2) in plasma as well as in lesional skin has been reported in vitiligo patients. High H2O2 level has been suggested to be responsible for the disappearance of melanocytes in vitiligo. JNK and p38 MAPK are strongly induced by oxidative stress and related to neuron loss in neurodegenerative disorders. Minocycline, an antibiotic possessing antioxidant activity, is capable of attenuating oxidative stress-induced neurotoxicity. To investigate whether minocycline rescues melanocytes from H2O2-induced apoptosis, cultured mouse melanocytes (B10BR) were treated with H2O2 in the presence or absence of minocycline. Our data showed that H2O2 decreases cell viability in a concentration-dependent manner which is attenuated by minocycline. Also, H2O2 treatment activates JNK and p38 MAPK, and executive caspase 3 in B10BR cells. Minocycline significantly inhibits H2O2-induced activation of JNK, p38 MAPK and caspase 3. Collectively, we concluded that minocycline protects melanocytes against H2O2-induced apoptosis in vitro. Its protective effect is associated with the inhibition of JNK and p38 MAPK. Our findings suggest that minocycline, a clinically well-tolerated, safe antibiotic, may be used to prevent melanocyte loss in the early stage of vitiligo.     

Mechanisms of H2O2-induced oxidative stress in endothelial cells exposed to physiologic shear stress

Hydrogen peroxide (H2O2) is produced by inflammatory and vascular cells and induces oxidative stress, which may contribute to vascular disease and endothelial cell dysfunction. In smooth muscle cells, H2O2 induces production of O2 by activating NADPH oxidase. However, the mechanisms whereby H2O2 induces oxidative stress in endothelial cells are not well understood, although O2 may play a role. Recent studies have documented increased O2 in endothelial cells exposed to H2O2 via uncoupled nitric oxide synthase (NOS) and NADPH oxidase under static conditions. To assess responses to H2O2 in porcine aortic endothelial cells (PAEC) under shearing conditions, a constant flow rate of 24. 4 ml/min was applied to produce physiologically relevant shear stress (8. 2 dynes/cm). Here we demonstrate that treatment with 100 muM H2O2 increases intracellular O2 levels in PAEC. In addition, we demonstrate that l-NAME, an inhibitor of NOS, and apocynin, an inhibitor of NADPH oxidase, reduced O2 levels in PAEC treated with H2O2 under physiologic shear suggesting that both NOS and NADPH oxidase contribute to H2O2-induced O2 in PAEC. Co-inhibition of NOS and NADPH oxidase also reduced intracellular O2 levels under shear. We conclude that H2O2-induced oxidative stress in endothelial cells exhibits increased intracellular O2 levels through NOS and NADPH oxidase under shear. The inhibition of NOS and NADPH with H2O2 exposure is nonlinear, suggesting some interdependent or compensating system within endothelial cells. These findings suggest a complex interaction between H2O2 and oxidant-generating enzymes that may contribute to endothelial dysfunction in cardiovascular diseases.     

管花苷B对抗H202诱导的PCI2细胞凋亡

目的:观察肉苁蓉提取物管花苷B对H:O:诱导的PCI2细胞损伤的影响.方法:用MTr法检测细胞存活率,以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化,DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生,并用荧光酶标仪测定caspase-3的活性.结果:100 μmol稬-1H2O2处理细胞24 h显著降低细胞的存活率;诱导细胞发生凋亡,凋亡率达48.O％;细胞内活性氧水平及caspase-3的活性显著升高;而线粒体膜电位却明显降低,红／绿荧光强度的比值由正常的5.97降低为0.41左右.而预先给予l、10或100 mg.L-1浓度的管花苷B处理细胞12 h,可显著提高细胞存活率;并可有效抑制DNA ladder的发生;流式细胞仪检测凋亡率分别降低到30.9％、18.3％和6.2％;激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平;并可逐渐恢复线粒体的高能量状态;easpase-3的活性不断降低,并呈现了一定的剂量依赖性.结论:管花苷B能显著地抑制H2O2诱导的PCI2细胞凋亡,其神经细胞保护作用可能与其降低细胞内活性氧水平,维持线粒体膜电位的高能状态和抑制caspase-3的活性有关.     

Interleukin-4 downregulates interleukin-6 production in human peripheral blood mononuclear cells

We report that recombinant human interleukin-4 (IL-4) downregulates interleukin-6 (IL-6) production by human peripheral blood mononuclear cells (PBMC). PBMC were preincubated for up to 24 hr in the presence of IL-4 (100 U/ml) and then activated with lipopolysaccharide B Escherichia coli 026:B6 (LPS, 10 micrograms/ml), recombinant human tumor necrosis factor-alpha (TNF-alpha, 200 U/ml), or Concanavalin A (Con A, 10 micrograms/ml). Although all these signals induced IL-6 production, IL-4-treated cells produced significantly reduced levels of IL-6 protein. This effect was dose and time dependent. We conclude that IL-4 is a potent downregulatory modulator of IL-6 expression in human PBMC.     

Interleukin-2 inhibits the interleukin-4-induced human IgE and IgG4 secretion in vivo.

The effect of interleukin-2 (IL-2) on IL-4-induced IgE and IgG4 secretion by B cells in peripheral blood mononuclear cell (PBMC) preparations from non-atopic healthy humans and atopic dermatitis patients was investigated. PBMC were cultured at an optimal concentration of recombinant IL-4 with or without addition of IL-2 for 10 days. Native and recombinant IL-2 inhibited the IL-4-induced IgE and IgG4 secretion in a dose-dependent manner by cells from both normal and atopic donors. Rabbit antibodies to IL-2 or to the monoclonal anti-IL-2 receptor antibody anti-TAC reversed the IL-2 effect. Culturing cells with IL-4 and IL-2 for 1 or 2 days only slightly suppressed the IgE and IgG4 secretion whereas addition of IL-2 to IL-4 containing cultures on day 4 or 5 inhibited the IgE and IgG4 secretion more effectively. This is in contrast to interferon-gamma (IFN-gamma) which inhibited the IL-4 induced IgE and IgG4 secretion when added for the first 24 or 48 h but had no effect when added on days 4 or 5. The data demonstrate that both IL-2 and IFN-gamma act as antagonists in the IL-4-induced IgE and IgG4 secretion by human B cells; while IL-2 appears to inhibit relatively late in culture, IFN-gamma has an early inhibitory effect, suggesting that the two lymphokines inhibit the IL-4 effect by different mechanisms.     

Guiqi polysaccharide protects the normal human fetal lung fibroblast WI-38 cells from H2O2-induced premature senescence

Objective: This study is to investigate the effects of Guiqi polysaccharide (GQP) on H₂O₂-induced premature senescence in normal human fetal lung fibroblast WI-38 cells. Methods: WI-38 cells were subjected to treatments of GQP, Angelica sinensis polysaccharide (ASP), and Astragalus membranaceus polysaccharide (AMP), and then treated with H₂O₂ to induce premature senescence. Morphological observation, MTT assay, senescence-associated β-galactosidase activity assessment, telomerase activity determination, cell cycle analysis, and Western blot analysis were performed to evaluate cellular senescence. Results: H₂O₂ treatment induced premature senescence in WI-38 cells, as indicated by the decreased fibroblast proliferation activity and changed cellular morphology. When treated with GQP, ASP, or AMP, the morphological changes in WI-38 cells induced by H₂O₂ could be restored. SA-β-gal activity was elevated in H₂O₂-treated WI-38 cells, which could be decreased by GQP treatment. Moreover, compared with the normal control, H₂O₂ treatment significantly inhibited the telomerase activity of WI-38 cells. However, GQP effectively elevated the telomerase activity of these senescent cells. Furthermore, flow cytometry and cell cycle analysis showed that GQP treatment could abrogate the cell cycle arrest in H₂O₂-treated WI-38 cells, which might contribute to the anti-senescent effects. In addition, GQP significantly affected the p53-p21 and p16-pRb pathways in H₂O₂-treated WI-38 cells. The effectiveness of GQP was superior to AMP or ASP treatment alone. Conclusion: GQP has protective effects in oxidative stress-induced senescence. Our findings suggest the promising role of GQP as an attractive and bio-safe agent with the potential to retard senescence and attenuate senescence-related diseases.     

Endotoxin and mast cell granule proteases synergistically activate human coronary artery endothelial cells to generate interleukin-6 and interleukin-8.

Mast cells (MC) are strategically located along blood vessels and, on activation, exocytose granules that contain many vasoactive mediators. Endothelial cell (EC) activation, which includes the production of such cytokines as interleukin-6 (IL-6) and IL-8, is a key event in vascular inflammation. In this study, the effects of purified MC granules (MCG) on the production of IL-6 and IL-8 by human coronary artery EC (HCAEC) were examined. HCAEC were cocultured with MCG in the presence or absence of lipopolysaccharide (LPS), and IL-6 and IL-8 levels in the culture medium were assayed by ELISA. Unactivated HCAEC produced only low levels of IL-6 or IL-8, and the addition of MCG alone resulted in little or no increase in production of these cytokines. LPS-activated HCAEC produced significant amounts of IL-6 and IL-8 in a dose-dependent and time-dependent fashion, which was amplified 2-3-fold by MCG at EC/MC ratios of 16:1-2:1. Scanning electron microscopy revealed direct communication between MCG and HCAEC. The enhancement of IL-6 and IL-8 production by MCG was abrogated when MCG were pretreated with the serine protease inhibitor phenylmethylsulfonyl fluoride (PMSF). These results demonstrate that MCG interaction with HCAEC causes amplification of endotoxin-stimulated cytokine production via serine proteases present in MCG. The synergistic activation of EC by endotoxin and MCG proteases emphasizes the role of MC in amplifying vascular inflammation.     

瘦素抑制H_2O_2诱导的大鼠心肌细胞凋亡

目的:观察瘦素(leptin)对H2O2诱导的大鼠心肌细胞凋亡的影响并探讨其作用机制。方法:应用脱氧三磷酸尿苷缺口末端标记(TUNEL)法观察瘦素对H2O2诱导的大鼠心肌细胞H9c2凋亡的影响;应用Western blotting法观察瘦素、H2O2对caspase-3、胞外信号调控激酶(ERK)活性的影响。结果:(1)瘦素对H2O2诱导的H9c2细胞凋亡具有显著的抑制作用(与对照组比较P0.01),该作用可被ERK激酶抑制剂PD98059所阻断。(2)H2O2明显抑制ERK活性;而瘦素可激活ERK并部分阻断H2O2诱导的caspase-3激活。结论:瘦素对H2O2诱导的H9c2细胞凋亡具有抑制作用,其机制可能与其激活ERK信号途径有关。     

Parkinson's disease genetic mutations increase cell susceptibility to stress: mutant alpha-synuclein enhances H2O2- and Sin-1-induced cell death

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder characterized by selective loss of dopaminergic neurons and the presence of Lewy bodies. Alpha-synuclein is a major component of Lewy bodies in sporadic PD, and genetic alterations in alpha-synuclein cause autosomal-dominant hereditary PD. The pathogenesis of PD remains incompletely understood, but it appears to involve both genetic susceptibility and environmental factors. Here we investigated the effect of alpha-synuclein expression on cell susceptibility to proteasome inhibition, oxidative and nitrative stresses by using a PC 12-Tet-off regulatory system. We found that inducible expression of A30P or A53T mutant alpha-synuclein decreased the proteasome activity, increased intracellular ROS levels, and enhanced lactacystin- and H2O2-induced cell death. Furthermore, 3-nitrotyrosine levels increased in cells expressing alpha-synuclein, and further increased after Sin-1 (a NO donor) treatment compared with untreated or treated non-induced cells. Expression of alpha-synuclein (mutant more than wild type) significantly enhances Sin-1 toxicity. These results indicate that genetic mutations in alpha-synuclein may increase neuronal vulnerability to cellular stress in aging and PD pathogenesis.     

Immune evasion proteins gpUS2 and gpUS11 of human cytomegalovirus incompletely protect infected cells from CD8 T cell recognition

Human cytomegalovirus (HCMV) encodes four glycoproteins, termed gpUS2, gpUS3, gpUS6 and gpUS11 that interfere with MHC class I biosynthesis and antigen presentation. Despite gpUS2-11 expression, however, HCMV infection is efficiently controlled by cytolytic CD8 T lymphocytes (CTL). To address the role of gpUS2 and gpUS11 in antigen presentation during viral infection, HCMV mutants were generated that expressed either gpUS2 or gpUS11 alone without coexpression of the three other proteins. Fibroblasts infected with these viruses showed reduced HLA-A2 and HLA-B7 surface expression. Surprisingly, however, CTL directed against the tegument protein pp65 and the regulatory IE1 protein still recognized and lysed mutant virus infected fibroblasts. Yet, suppression of IE1 derived peptide presentation by gpUS2 or gpUS11 was far more pronounced. The results show that gpUS2 and gpUS11 alone only incompletely protect HCMV infected fibroblasts from CTL recognition and underline the importance of studying infected cells to elucidate HCMV immune evasion.     

Production by cultured human monocytes of mesangial cell proliferation factor(s) differing from interleukin-1 and interleukin-6.

Conditioned media from human peripheral blood leucocytes treated with lipopolysaccharide (LPS) induced a marked increase in the 3H-thymidine incorporation of cultured mesangial cells at low serum concentration (four to six times higher than control). Two sizes (100-70 and 8-12 kD) of monocyte-derived mesangial cell proliferating factors (MDF) were separated by column chromatography. Their peaks were distinct from those of thymocyte proliferating activity. The addition of anti-human interleukin-1 (IL-1) or anti-recombinant human interleukin-6 (IL-6) antibody to the fractionated MDF failed to have any effect on the mitogenic activity toward mesangial cells. The addition of anti-human platelet-derived growth factor (PDGF) antibody to the low molecular weight fraction decreased mesangial cell mitogenic activity (40-60% of control), but addition to the higher fraction did not (80-100% of control). From these data it seems that a large portion of the monocyte-derived mesangial cell growth factor was not comprised of IL-1 or IL-6 but of PDGF-like molecules; and that there is an unknown mesangial cell proliferating factor (or factors) besides IL-1, IL-6 and PDGF.     

硫化氢对抗过氧化氢对PC12细胞的损伤作用

目的探讨硫化氢(hydrogen sulfide,H2S)对抗过氧化氢(hydrogen peroxide,H2O2)对PC12细胞的损伤作用及有关机制。方法应用H2O2在PC12细胞建立氧化应激损伤的实验模型;应用甲氮甲唑蓝(MTT)法检测细胞存活率,碘化丙啶(PI)染色流式细胞技术(FCM)检测细胞凋亡率,罗丹明123(Rhodamine 123,Rh123)染色FCM检测细胞线粒体膜电位(mitochondrial membrane potential,MMP),双氢罗丹明123染色FCM检测细胞内活性氧(reactive oxygen species,ROS)的含量。应用硫化氢钠(sodium hydrosulfide,NaHS)作为H2S的供体。结果200μmol和400μmolH2O2作用PC12细胞24h均使细胞的存活率明显降低及凋亡率显著增加,200μmolH2O2引起PC12细胞的MMP明显降低及ROS生成显著增多。当NaHS与H2O2(200或400μmol/L)共同作用于PC12细胞时,NaHS(100～400μmol/L)浓度依赖性的阻断H2O2引起PC12细胞的存活率降低及细胞凋亡率增加。400μmolNaHS明显地阻断200μmolH2O2引起PC12细胞的MMP降低及ROS增多。结论H2S能明显地保护PC12细胞对抗H2O2引起的损伤,阻断MMP降低及ROS生成可能是H2S的细胞保护机制之一。