Effects of lipoxin A4 on proliferation and IL-2/IL-2 receptor expression in Jurkat T cells

AIM: To investigate the effect of lipoxin A4 on the proliferation and IL-2 production in Jurkat T cells. METHODS: Jurkat T cells were activated in vitro with anti-CD3 (2 mg/L) and anti-CD28 (2 mg/L) antibodies in the absence or presence of lipoxin A4 (0.1 nmol/L-100 nmol/L) for 24 h, then ［3H］-TdR was added into the medium and radioactivities were measured by scintillation counting. The concentrations of IL-2 in the supernants were determined by ELISA. Cells were harvested and the expression of CD25 was assessed by FCM. For analysing the cell cycle, the cells were stained with PI and DNA contents were detected by FCM. RESULTS: Lipoxin A4 suppressed the proliferation of anti-CD3 and anti-CD28 antibodies activated Jurkat cells in a dose-dependent manner, which was associated with reduced proportion of S phase cells. Furthemore, lipoxin A4 significantly inhibited the production of IL-2 but had no obvious effect on CD25 expression. CONCLUSION: Lipoxin A4 can suppress proliferation of activate Jurkat cells and IL-2 production, through which lipoxin A4 might negatively regulate immune response.     

Construction of pLNCX/anti-CD20scFv/IgGFc/CD80/CD28/ζ eukaryotic expression vector and expression in NIH 3T3 cells

AIM: To construct a recombinant eukaryotic expression vector pLNCX/anti-CD20scFv/IgGFc/CD80/CD28/ζ and detect its expression in NIH 3T3 cells.METHODS: CD28-ζ cDNA was amplified from the plasmids pBULLET and inserted into pLNCX vector that contained anti-CD20 scFv/IgGFc/CD80 gene.The recombinant plasmids were transfected into NIH 3T3 cells,and resistant clones were obtained by G418 selection.The gene expression of the fusion protein was determined by RT-PCR and FACS.RESULTS: The recombinant eukaryotic vector was constructed successfully,determined by PCR and enzyme digestion analysis.The target gene was amplified from NIH 3T3 cells transfected with the vectors by RT-PCR.The FACS showed that recombinant protein was expressed in NIH 3T3 cells.CONCLUSION: Construction of pLNCX/anti-CD20scFv/IgGFc/CD80/CD28/ζ expression vector and its expression in NIH 3T3 cells lay the foundation for further research of generation of modified T lymphocytes to CD20 positive lymphoma.     

Effects of oxymatrine on lymphocyte proliferation and the quantity of regulatory T cells

AIM: To analyze the effects of oxymatrine (OMT) on the quantity of murine regulatory T cells (Tr cells) in the peripheral blood and mouse lymphocyte proliferation stimulated by Con A, and to probe into the immunological mechanism that OMT treats allergic contact dermatitis (ACD).METHODS: An ACD mouse model stimulated by dinitrofluorobenzene (DNFB) was established. Different dosages of OMT, PBS and hydrocortisone (HCT) were intraperitoneally injected (IP) into the mice. Blood samples were collected at〖JP+2〗 1 d, 7 d, 14 d, 21 d and 28 d, then the T cells were isolated and marked with anti-CD3, anti-CD4, anti-CD25 three-colored immune fluorescence antibody to detect the quantity of CD4+CD25+ T cells with flow cytometry. The fluorescence intensity changes of lymphocytes which were isolated from mouses lymph node and co-stimulated by polyclonal stimulator Con A and OMT were examined by carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) staining and flow cytometry. RESULTS: OMT at concentrations of 500, 125 and 31 mg/L had the ability to restrain the proliferation of lymphocytes from lymph node in a dose dependent manner. However, OMT at concentrations of 16, 8, 4 and 2 mg/L promoted the proliferation of T lymphocytes from lymph node, but was not obviously dependent on its concentration. Intraperitoneal injection of OMT increased the numbers of CD4+CD25+T cell in peripheral blood obviously (P<0.01). CONCLUSION: The effects of OMT on the proliferation of T lymphocytes from mouses lymph node cells are observed, OMT also increases the CD4+CD25+T cells in the peripheral blood, implying that OMT is a kind of immunoregulator with dual effects.     

Kinetic expressions of PD-L1 and PD-L2 on the surface of human lymphocytes and monocytes

AIM: To investigate the expression kinetics of PD-L1 and PD-L2 on the surface of the resting and activated B/T cells as well as monocytes from healthy human peripheral blood. METHODS: Fluorescent antibody staining together with flow cytometry were used to detect the percentages of the resting as well as the activated B cells and T cells that expressed PD-L1 and PD-L2. Meanwhile the percentages of the resting and activated monocytes that expressed PD-L2 were determined. RESULTS: Both resting B cells and T cells did not express PD-L1 on their surface, however PD-L1 expression was significantly up-regulated on the surface of the activated B cells after 6 h stimulation with LPS or pokeweed mitogen (PWM), and the percentages of B cells that expressed PD-L1 reached a plateau at 24 h, which were (46.26±10.71)% with LPS and (43.67±6.14)% with PWM stimulation, respectively. No markedly change of PD-L1 expression on the surface of the activated T cells after stimulation with LPS was observed, but upregulation of PD-L1 expression was observed when stimulation with PWM. The percentages of T cells that expressed PD-L1 reached a plateau at 24 h, which was (25.42±9.23)%. PD-L2 expression was not found on the resting as well as the activated B cells and T cells. In addition, the resting monocytes did not express PD-L2. Combination of INF-γ plus LPS markedly induced the PD-L2 expression, and the percentages of monocytes that expressed PD-L2 reached a peak at 48 h, which was (28.70±14.22)%. CONCLUSION: The activated lymphocytes only express PD-L1, reaching a plateau at 24 h. PD-L2 is expressed on the surface of the activated monocytes, reaching a peak at 48 h.     

ox-LDL increases endothelial lipase in RAW264.7 macrophages

AIM: To investigate the effect of oxidized low-density lipoprotein (ox-LDL) on the expression of endothelial lipase (EL) in murine RAW264.7 macrophages. METHODS: RAW264.7 cells were incubated with ox-LDL at concentrations of 0~100 mg/L for 24 h.On the other hand, the cells were incubated with or without PDTC (NF-κB inhibitor) for 30 min and then with ox-LDL (50 mg/L) for 24 h. The expression of EL and p65 was detected by Western blotting. RESULTS: The level of EL was significantly increased after ox-LDL incubation in RAW264.7 cells (P<0.05). NF-κB was activated by ox-LDL at concentration of 50 mg/L for 15~30 min in RAW264.7 cells. The increase in EL induced by ox-LDL was markedly inhibited by a NF-κB inhibitor PDTC (P<0.05). CONCLUSION: ox-LDL significantly increases the expression of EL in RAW264.7 macrophages, which is possibly related to NF-κB activation.     

Influence of histone deacetylase inhibitor romidepsin on phenotype and function of T lymphocytes in vitro

AIM: To explore the effects of romidepsin (FK228), a novel histone deacetylase inhibitor, on the effector and regulatory T cells in vitro.METHODS: As the reactive cells, lymphocytes, CD4⁺ T cells and CD8⁺ T cells were labelled with CFSE, and stimulated with anti-CD3 and anti-CD28 mAbs in the presence and absence of different levels of romidepsin (experimental group and positive control group), or PBS (placebo group).After 72 h, the proliferation of the cells was detected in different groups. The lymphocytes were stimulated with anti-CD3 and anti-CD28 mAbs in the presence and absence of different levels of romidepsin (experimental group and positive control group),or PBS (placebo group). After 72 h, the percentage of CD4⁺ Foxp3⁺ T cells and the levels of related cytokines were detected in different groups. RESULTS: The proliferation of CFSE-labelled lymphocytes, CD4⁺ T cells and CD8⁺ T cells triggered by anti-CD3 and anti-CD28 mAbs all were inhibited when cultured with romidepsin at concentrations of 1 μmol/L, 3 μmol/L and 5 μmol/L in a dose-dependent manner (P<0.05). Compared with placebo group, in the presence of anti-CD3 and anti-CD28 mAbs, 1 μmol/L romidepsin did not increase the percentage of CD4⁺ Foxp3⁺ T cells (P>0.05). When cultured with romidepsin at concentrations of 3 μmol/L and 5 μmol/L, the percentage of CD4⁺ Foxp3⁺ T cells was enhanced markedly (P<0.05). The levels of IL-10 and TNF-α in the supernatant were markedly increased in positive control group and 3 experimental groups (P<0.05), and the levels of cytokines in different experimental groups were gradually decreased with the elevation of FK228 concentration (P<0.05). The level of TGF-β was slightly increased in positive control group with no significant difference compared with placebo group (P>0.05). With the increase in the concentration of FK228 in different experimental groups, the TGF-β level was increased in a dose-dependent manner and there were significant differences in the 3 experimental groups. Meanwhile, significant differences existed between experimental groups and placebo group and between experimental groups and positive control group (P<0.05). CONCLUSION: Romidepsin inhibits the proliferation of CD4⁺ and CD8⁺ effector T cells and increases the percentage of CD4⁺ Foxp3⁺ regulatory T cells. It may be related to the increased level of TGF-β, but independent of IL-10.     

Foam cells can be induced by oxidized low density lipoprotein in human monocyte-derived dendritic cells

AIM: The purpose of this study is to investigate the mechanisms related to oxidized low-density lipoprotein (ox-LDL) and dendritic cells (DCs) in the process of atherosclerosis.METHODS: Human DCs were prepared from human CD14+ peripheral blood monocytes using rhGM-CSF (100 μg/L) and rhIL-4 (40 μg/L).Cells were incubated with 100 mg/L native or oxidized LDL for 72 h.The formation of foam cells was investigated by electron microscopy and oil red O staining.Phenotypic and immune functional assays were used with FACS, FITC-dextran phagocytosis, allogeneic mixed T lymphocytes reaction and secretion of Th1/Th2 (IL-12/IL-2) cytokines were also conduced.RESULTS: DCs treated with ox-LDL, but not native LDL were induced into foam cells after cultured for 72 h.Compared with native LDL, ox-LDL-treated DCs were less potent in FITC-dextran phagocytosis.ox-LDL promoted allogeneic T cells proliferation.Moreover, ox-LDL upregulated CD80 (72.4± 9.6 vs 89.5±10.1, P<0.01), CD86 (67.2±8.8 vs 80.2±11.6, P<0.01), HLA-DR (80.6±9.8 vs 86.6±10.8, P<0.01) and CD1a (40.2±10.3 vs 60.2±9.3, P<0.01) expressions, increased IL-12 secretion ［(44.3±8.9)ng/L vs (65.1±10.4)ng/L, P<0.05］ in DCs.However, the secretion of IL-2 was decreased ［(43.6±7.8)ng/L vs (10.0±4.5 )ng/L, P<0.01］ significently.CONCLUSION: DCs were induced into foam cells by ingesting ox-LDL with some functional characteristic of mature DC.DCs seem to be a new source of foam cells and play a key role in immunopathogenesis of atherosclerosis.     

Effect of TAP-SSL5 fusion protein on binding of activated platelets to human lymphocytes

AIM: To study the effect of tick anticoagulant peptide-staphylococcal superantigen like protein 5 (TAP-SSL5), an anti-inflammatory and anticoagulant fusion protein, on the binding of activated platelets to human lymphocytes.METHODS: Human periphery lymphocytes were isolated by magnetic activated cell sorting (MACS). The toxicity of TAP-SSL5 on the viability of Jurkat cell was assessed by CCK-8 assay. Flow cytometry was applied to detect the expression of CD162 (PSGL-1) on the Jurkat cells (human peripheral blood leukemia T lymphocyte cell line) and the inhibitory effect of TAP-SSL5 on the binding of mouse anti-human CD162 monoclonal antibody (KPL-1) to Jurkat cells. Platelets were activated by ADP at concentration of 20 μmol/L, the binding rates of activated platelets to Jurkat cells or human lymphocytes were assayed by flow cytometry. RESULTS: The concentration of TAP-SSL5 below 30 mg/L didn't affect the viability of Jurkat cells. TAP-SSL5 at 10 mg/L competitively inhibited KPL-1 binding to Jurkat cells. The binding rates of activated platelets to Jurkat cells or lymphocytes were (11.86±4.49)% and (8.32±1.00)%, respectively, which decreased to (6.73±2.71)% and (5.51±0.70)% after the Jurkat cells and lymphocytes were pre-incubated with 10 mg/L TAP-SSL5 (P <0.05).CONCLUSION: TAP-SSL5 binds to PSGL-1 expressed on lymphocyte surface and directly inhibits the binding of activated platelets to human lymphocytes, which may be one of the anti-inflammatory mechanisms of TAP-SSL5.     

Effect of advanced glycosylation end products on the expression of receptor for advanced glycosylation end products in human monocyte-derived dendritic cells

AIM: To investigate the effect of advanced glycosylation end products on the expression of receptor for advanced glycosylation end products in human monocyte-derived dendritic cells. METHODS: Monocytes were purified (over 98%) using anti-CD14＋ microbeads. After 8 d culture in RPMI-1640 medium containing rhGM-CSF (100 μg/L) and rhIL-4 (50 μg/L), immature MDCs were derived, then exposed to AGE-BSA (0 or 200 mg/L) for 24 h. Expression of RAGE was semi-quantified by RT-PCR and Western blotting. At the same time, supernatants were collected. IFN-γ and IL-12 were analyzed by ELISA. RESULTS: mRNA and protein of RAGE incubated by 200 mg/L AGE-BSA was higher than that in control at 24 h. Treatment of DCs with AGE-BSA resulted in about two-fold increase in the expression of RAGE (P<0.05). The concentrations of IFN-γ and IL-12 were both significantly higher than that in control (P<0.05). CONCLUSION: AGEs up-regulates the expression of RAGE and induces the secretion of IFN-γ and IL-12 by DCs. These findings may provide insight into the effect of DCs on the processes of atherosclerosis.     

Analysis of T cell activation and regulatory T cell derived from murine Peyer's patches

AIM: To explore the characteristics of T cell activation and regulatory T cells derived from murine Peyer's patches through comparative studies on Peyer's patches, mesenteric lymph nodes and inguinal lymph nodes. METHODS: Signal cell suspendsions were prepared from murine mesenteric lymph nodes (MLNs), the Peyer's patches (PPs) and inguinal lymph nodes (ILNs), respectively. The percentage of cell subpopulations such as CD3+ T cells, CD3+CD4+ helper T cells and regulatory T cells (Treg, CD4+CD25+) were analyzed. Lymphocytes were activated by polyclonal stimulators such as concanavalin (Con A), phorbol 12, 13-dibutyrate (PDB) only, and PDB plus ionomycin (Ion). The expression of CD69 (the early marker of CD3+ T cell activation) was measured by FACS. RESULTS: A lower ratio of CD3+ T cells was seen in PPs than those in MLNs and ILNs. The ratios of CD3+ CD4+ T cells to CD3+ T cells in PPs, MLNs and ILNs were almost the same. A higher rate of Treg was seen in CD4+ T cells from the PPs as compared with those from MLNs and ILNs. A higher percentage of activated CD3+ T cells derived from the PPs cultured without polyclonal stimulators were detected as compared to MLNs and ILNs, while lower responsiveness of CD3+ T cells from the PPs stimulated by Con A was seen as compared with those from MLNs and ILNs. CONCLUSIONS: The lower rate of CD3+ T cells as well as higher rate of Treg in PPs was due to its desensitization. The higher rate of basic activated state in CD3+ T cells from the PPs indicated that the T cells were activated by enteric antigens in physiological conditions. The lower responsiveness of activation to some polyclonal stimulators probably reveals that the T cells are in a state of anergy. All the characteristics mentioned above contribute to prevent pathological inflammations and maintain tolerance to enteric antigens such as food proteins and commensal bacteria but simultaneously retain proper immune responses to pathogenic microbes.     

XBP-01 accelerated apoptosis induced by oxidized low density lipoprotein in vascular smooth muscle cells

AIM: Previous studies performed with XBP-01 in vitro indicated that XBP-01 could inhibit vascular smooth muscle cells from being transformed into foam cell and could eliminate the atherosclerotic plaque in C57BL/6J mouse. This experiment is to investigate its mechanism of eliminating plaques in vitro. METHODS: The cultured porcine artery smooth muscle cells incubated with XBP-01 of 0.1 mg/L for 24 h after preincubated with oxidized low density lipoprotein of 15 mg/L for 72 h in vitro. The samples were analyzed by fluorescence microscope, confocal microscope system and flow cytometry. RESULTS: Apoptosis was triggered by being incubated with oxidized low density lipoprotein and this process was accelerated additionally by being incubated with XBP-01. CONCLUSION: XBP-01 can be effective in eliminating atherosclerotic plaque by accelerating the process in which oxidized low density lipoprotein induced smooth muscle cell apoptosis.     

Effect of salvianolic acid B on expression of TGF-β1 receptors and Smad2 in activated mesangial cells

AIM: To study the mechanisms of salvianolic acid B (Sal B)antagonizing mesangial cell activation and kidney fibrosis through investigating the effect of Sal B on expression of transforming growth factor-β₁ (TGF-β₁) receptors and Smad2 in TGF-β₁-stimulated renal mesangial cell activation. METHODS: Mesangial cells was isolated and purified from rat kidney. TGF-β₁ was used to establish rat primary mesangial cell activation model and Smad2,Smad7 protein expression was detected. Sal B (10^-6 mol/L and 10^-5 mol/L) was employed to treat the cells; α-smooth muscle actin(α-SMA) expression was analyzed by immunofluorescence staining and Western blotting. Mesangial cells were treated with Sal B alone or additional with TGF-β₁,and TGF-β₁ receptor Ⅰ (TβRⅠ),TGF-β₁ receptorⅡ (TβRⅡ),Smad2 phosphorylation and Smad2 protein expression was determined by Western blotting. RESULTS: Cell ular model was established by incubating with 5 μg/L TGF-β₁ for 24 h,and in early stage Smad2 was significantly phosphorylated. Sal B (10^-6 mol/L and 10^-5 mol/L) could inhibit α-SMA expression,which was the biomarker of activated mesangial cells. In addition,in Sal B group,the protein expression of TβRⅠand TβRⅡ was significantly down-regulated while Smad2 phosphorylation in mesangial cells was inhibited. CONCLUSION: Sal B inhibits the TGF-β₁-Smad pathway,the protein expression of TβRⅠ,TβRⅡ and Smad2 phosphorylation in mesangial cells,which is probably one of the mechanisms of Sal B alleviating kidney fibrosis.     

Effect of CD137-CD137 ligand interaction on expression of NFATc1 in apolipoprotein E-deficient mice

AIM: To observe the effects of CD137-CD137 ligand(CD137L) interaction on the nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) in apolipoprotein E-knockout (ApoE^-/-) mice. METHODS: Atherosclerotic plaque model was produced by perivascular carotid collar placement in ApoE^-/- mice. In vivo, the expression levels of NFATc1 in mouse plaques and lymphocytes were detected by immunohistochemical method and flow cytometry, respectively. In vitro, the expression of NFATc1 at mRNA and protein levels in cultured lymphocytes of ApoE^-/- mice was measured by RT-PCR and flow cytometry, respectively. RESULTS: In vivo, after CD137-CD137L signaling pathway was stimulated, the expression of NFATc1 was significantly increased in the atherosclerotic plaques and lymphocytes. In vitro, the expression of NFATc1 at mRNA and protein levels in cultured leukocytes of ApoE^-/- mice was also significantly increased, with the maximal effect exerted by anti-CD137 monoclonal antibody (mAb) at the concentration of 20 mg/L, and 24 h after stimulation at any concentration (P<0.05). Anti-CD137L mAb significantly inhibited the expression of NFATc1 at mRNA and protein levels in the lymphocytes of ApoE^-/- mice, with the maximal effect exerted by anti-CD137L mAb at the concentration of 20 mg/L, and 24 h after stimulation (P<0.05). CONCLUSION: CD137-CD137L interaction can regulate the expression of NFATc1 in ApoE^-/- mice.     

High glucose up-regulates TRAIL-R4 expression in THP-1 cells and smooth muscle cells

AIM: To evaluate the expression of TNF-related apoptosis inducing ligand receptor 4 (TRAIL-R4) of THP-1 cells and human aorta smooth muscle cells under high glucose intervention. METHODS: Monocytic cell line THP-1 was incubated with PMA to induce to mature macrophage, Adhesion molecules CD11b and CD11c were assessed by FACS. TRAIL-R4 levels in THP-1 cells treated with different glucose concentrations were determined by Western blotting. The changes of TRAIL-R4 protein expressions were observed at different time points in human aorta smooth muscle cells. Western blotting was employed to evaluate TRAIL-R4 levels after the intervention of PKC activator. RESULTS: Incubation with 160 nmol/L PMA induced mature macrophages. TRAIL-R4 expression was up-regulated after incubation with 20 mmol/L glucose in macrophages. TRAIL-R4 was elevated in a time course manner under high glucose level in human aorta smooth muscle cells. Moreover, activation of PKC induced TRAIL-R4 expressions. CONCLUSION: Up-regulated TRAIL-R4 protein levels induced by high glucose levels might inhibit apoptosis of monocytes and smooth muscle cells and contribute to the progression of atherosclerosis.     

Hepatocyte growth factor enhances the neural differentiation from human embryonic stem cells

AIM: To investigate the possibility that hepatocyte growth factor (HGF) directly induces differentiation of human embryonic stem cells (hESCs) into neural progenitors (NPs). METHODS: hESCs colonies were induced to form the embryoid body (EB). Four-day-old EBs were randomly divided into 4 groups: control group (EBs were cultured in neural induction medium); G5 supplement group (EBs were cultured in neural induction medium supplied with G5 supplement); HGF group (EBs were cultured in neural induction medium supplied with 10 mg/L HGF), and HGF+G5 group (EBs were cultured in neural induction medium supplied with 10 mg/L HGF and G5 supplement). After induced in suspension system for 7 days, EBs with various treatments were cultured in poly-D-lysine/laminin-coated plates for 7-10 days for selection of NPs. NPs were gathered by 0.3 g/L dispase treatment and characterized by immunofluorescence staining. The percentages of the nestin+ cells in NPs in various groups were detected by fluorescent activated cell sorter (FACS). The multipotency of NPs was determined by immunofluorescence staining after the NPs were cultured without G5 and HGF for 7 days. The expression of region markers of neural progenitors treated with sonic hedgehog (Shh) protein (one of the neural inductive signals), was detected by RT-PCR. RESULTS: HGF+G5 supplement induced hESCs differentiation into neural progenitors. Immunofluorescence staining indicated that NPs differentiated from hESCs expressed NP markers including nestin, Pax6 and musashi-1. FACS data showed that the proportion of nestin positive cells in HGF+G5 supplement group (87.3%±3.9%) was the highest in all treatment groups. The time of HGF and G5 supplement treatment was important to differentiate into NPs, the maximal effect was observed at 7th day. After treated with Shh, the expression of ventral forebrain/hindbrain marker genes (Nkk2.1, and Nkk2.2) and hindbrain progenitor marker gene Gbx2 in NPs were upregulated, while the forebrain progenitor marker genes Otx2 and Bf1 were downregulated. CONCLUSION: The neural induction system containing HGF and G5 supplement effectively induces the differentiation of hESCs into NPs, which might be a potent model for investigating the mechanism of neural development and differentiation.     

Production and cytotoxicity of the reactive oxygen species induced by diallyl trisulfide in human myeloid leukemia HL-60 cells

AIM: To explore the production and cytotoxicity of the reactive oxygen species (ROS) induced by diallyl trisulfide (DATS) in HL-60 cells.METHODS: HL-60 cells were either treated with various doses of DATS alone, or DATS combination with apocynin, a specific NADPH oxidase inhibitor, or with antioxidant N-acetyl-L-cysteine (NAC) for 0, 1, 3, 6, 12 and 24 h, respectively. The intracellular ROS level was measured by flow cytometry. The activity of NADPH oxidase was evaluated by NBT reduction experiment. The content of both malondialdehyde (MDA) and the protein carbonyl were analyzed by spectrophotometer. RESULTS: The results from flow cytometry indicated that DATS significantly increased the intracellular ROS level in HL-60 cells (P<0.05), which was dose-and time-dependent. The fluorescence intensities of ROS reached at maximum when HL-60 cells were incubated with 150 μmol/L DATS for 3 h. The NBT reduction experiment showed that DATS activated NADPH oxidase, the highest activity was observed when the cells were exposed to 150 μmol/L DATS for 3 h. DATS induced MDA and protein carbonyl production in HL-60 cells. Furthermore, both MDA and protein carbonyl reached the highest level in the cells exposed to 150 μmol/L DATS for 3 h. Apocynin and NAC attenuated the production of MDA and protein carbonyl, suggesting that ROS induced by DATS was involved in the toxicity to the cells. CONCLUSION: DATS induces ROS production through activating NADPH oxidase in HL-60 cells. ROS increases the oxidation of membrane lipid and protein in HL-60 cells.     

Oxidized low-density lipoprotein induces autophagy in macrophages via CD36-mediated oxidative stress

AIM: To investigate the effect of oxidized low-density lipoprotein (ox-LDL) on autophagy in macrophages and the underlying molecular mechanisms. METHODS: RAW264.7 macrophages were pretreated with 2 mg/L anti-CD36 monoclonal antibody (anti-CD36 mAb), 5 μmol/L diphenyleneiodonium (DPI), 3 mmol/L 3-methyladenine (3-MA) or 1 μmol/L rapamycin for 1 h and then treated with ox-LDL (100 mg/L) for 12 h. The viability of the cells was measured by MTT assay. The activities of lactic dehydrogenase (LDH) in the medium and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, superoxide dismutase (SOD) in the cells as well as the levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) were determined to characterize the membrane integrity and the oxidative stress, respectively. The protein levels of beclin-1 and microtubule-associated protein 1 light chain 3-II (LC3-II), 2 important molecular markers of autophagy, were examined by Western blotting. RESULTS: ox-LDL induced autophagy in RAW264.7 macrophages as assessed by upregulation of beclin-1 and LC3-II. Similar to 3-MA, an autophagy inhibitor, anti-CD36 mAb significantly inhibited the ox-LDL-induced upregulation of beclin-1 and LC3-II. Anti-CD36 mAb suppressed the ox-LDL-induced oxidative stress as revealed by decreased NADPH oxidase activation, ROS and MDA generation as well as increased SOD activity. Similar results were observed in the cells pretreated with DPI, a NADPH oxidase inhibitor. Moreover, DPI significantly inhibited the ox-LDL-induced upregulation of beclin-1 and LC3-II. Inaddition, the decrease in the cell viability and increase in LDH release induced by ox-LDL were promoted by 3-MA and blocked by rapamycin (an autophagy inducer). CONCLUSION: ox-LDL induces autophagy in RAW264.7 macrophages, which may be involved in CD36-mediated ox-LDL uptake and subsequent activation of oxidative stress, and moderate activation of autophagy may protect macrophages from ox-LDL-induced injury.     

Effect of camptothecin on the activation,proliferation and cell cycle distribution of the mouse T lymphocytes in vitro

AIM: To study the effects of camptothecin (CPT) on the activation, proliferation and cell-cycle distribution of the mouse T lymphocytes stimulated by concanvalin A (ConA) in vitro. METHODS: A model of T cell activation and proliferation was established by stimulated the cells with Con A. T cells were treated with different concentrations of CPT. The expression of CD69, the early marker of CD3+ T cell activation, was measured by FACS. The proliferation index was determined by carboxyl fluorescin diacetate succinmidyl ester by flow cytometry. The cell-cycle distribution was analyzed by propidium iodide staining. RESULTS: After stimulation with Con A for 6 h, the activation rate of CD69+ T cell in Con A group was (58.88±0.55)%. The percentages of CD69 positive cells were (55.48±0.98)%, (54.67±1.05)%, (50.40±0.82)%, (42.47±1.32)%, correspond to the treatments with different concentrations of CPT (10 nmol/L, 20 nmol/L, 50 nmol/L, 100 nmol/L), respectively. After 48 h treatment with Con A, the proliferation index in different concentrations of CPT treatment (10 nmol/L, 20 nmol/L, 50 nmol/L and 100 nmol/L) exerted a definite inhibitory effect on the proliferation (P<0.01). Moreover, the cell-cycle distribution analysis showed that apoptosis peak was observed in different concentrations of CPT treatment after 48 h cultured with Con A. CONCLUSION: CPT significantly inhibits the early stages of the Con A-induced T cell activation and proliferation, and detents the T lymphocytes in G₀/G₁ phase.     

Proliferation of CD4+CD25+ T cells from PBMCs of the gastric cancer patients and inhibitory effect on CD4+CD25- T cells in vitro

AIM:To investigate the proliferation of CD4+CD25+ T cells from PBMCs of the gastric cancer patients and the inhibitory effect on CD4+CD25- T cells in vitro. METHODS:Magnetic activated cell sorting (MACS) method was used to separate CD4+CD25+T and CD4+CD25-T cells from peripheral blood monocytic lymphocytes in the gastric cancer patients, and then the purity and activity of CD4+CD25+T cells were analyzed with flow cytometer. After stimulated with anti-CD3 Ab, anti-CD28 Ab and rh IL-2, CD4+CD25- and CD4+CD25+ T cells were cocultured. The inhibitory effect of CD4+CD25+T on CD4+CD25-T cells was assayed by ［3H］ thymidine proliferation experiment. RESULTS:(1)After sorting, CD4+CD25+ T cells purity in healthy control and gastric cancer patients were 83.80%±1.84% and 84.13%±2.77%, respectively. No significant difference between the two groups (P>0.05) was observed. (2)The activity of CD4+CD25+ and CD4+CD25- T cells in healthy control and the gastric cancer patients after sorting were 98.52%±0.72% and 97.80%±0.95%. There was no significantly difference between the two groups (P>0.05). (3) CD4+CD25+ T cells obviously inhibited the CD4+CD25-T cell proliferation in vitro. The inhibition achieved to maximum in coculture of CD4+CD25+ T cells together with CD4+CD25- T cells (ratio of 1∶〖KG-*2〗1). CONCLUSION:The MACS system can effectively isolate CD4+CD25+ and CD4+CD25- T cells. After sorting, CD4+CD25+T cells obviously inhibit the proliferation of CD4+CD25- T cells in vitro and the inhibitory effect display an effect-target ratio relationship.