Relationship between renal hypertension and cardiac α1-adrenoceptor autoantibodies in rats

AIM: To examine the autoantibody against α₁-adrenoceptor and its biologic activities during the development of renal hypertension. METHODS: Renal hypertension of rat was achieved by clipped renal artery, the titre of autoantibody to α₁-adrenoceptor was detected using ELISA immunoassay. Furthermore, the biological offects of these autoantibodies on cultured cardiomyocytes were also examined. RESULTS: After two weeks of clipping renal arteries, both the frequency of occurrence and the titre of autoantibodies to cardiac α₁-adrenergic receptor were significantly increased as compared with the control of pre-treatment. The increased autoantibodies lasted for several weeks and then automatically decreased gradually to the pre-clipping level at 12 weeks. The biological effects of these autoantibodies displayed an "agonistic-like" activities on the beating frequency of cultured neonatal cardiomyocytes. CONCLUSION: Autoantibodies against α₁-adrenoceptor may play a role in the elevation of peripheral vascular resistance and in the development of cardiac hypertrophy in rats with renal hypertension.     

Effects of several harmful factors on expression of glycine receptor α1 subunit in neonatal rat myocardial cells

AIM: To study the expression of glycine receptor α₁ subunit in neonatal rat myocardial cells and to investigate the effect of lipopolysaccharide (LPS), hypoxia/reoxygenation, isoproterenol (ISO) and high concentration of glucose (HG) on the expression of glycine receptor α₁ subunit in the neonatal rat myocardial cells. METHODS: Neonatal rat myocardial cells were cultured in vitro. The expression of glycine receptor α₁ subunit was detected by Western blotting. The neonatal rat myocardial cells were treated with LPS (20 mg/L), ISO (100μmol/L) or high concentration of glucose (25 mmol/L) for 24 h, or were exposed to hypoxia for 3 h followed by reoxygenation for 3 h. Subsequently, the cell viability was measured by CCK-8 assay, and the expression of glycine receptor α₁ subunit was determined by Western blotting. RESULTS: The expression of glycine receptor α₁ subunit in the neonatal rat myocardial cells was positively detectable by Western blotting. Compared with control group, no significant difference of the cell viability (P>0.05) in LPS group, ISO group, hypoxia/reoxygenation group and HG group was observed. The expression of glycine receptor α₁ subunit was increased (P<0.01) in LPS group, ISO group and hypoxia/reoxygenatio group, but decreased (P<0.01) in HG group. CONCLUSION: Glycine receptor α₁ subunit exists in the neonatal rat myocardial cells. A certain concentration of LPS or ISO, or hypoxia/reoxygenation for a certain period upregulate the expression of glycine receptor α₁ subunit, but HG downregulates the expression of glycine receptor α₁ subunit in cultured neonatal rat myocardial cells.     

Expression of MMP-2 and NF-κB in myocardium of mice with viral myocarditis

AIM: To observe the effects of TNF-α/nuclear factor-κB(NF-κB)/matrix metalloproteinase-2(MMP-2) pathway on the expression of MMP-2 in the mice with viral myocarditis. METHODS: Six-week-old inbred male mice were randomly assigned to control and myocarditis group. The mice in myocarditis group and control group were intraperitoneally inoculated with 0.1 mL 10^-5.69 TCID50/mL coxsackievirus B3 and vehicle (PBS), respectively. Ten mice were sacrificed at the 4th and 10th days after injection. The blood and heart specimens were harvested. The serum content of TNF-α was measured by ELISA. The myocardial levels of MMP-2, NF-κB p65 and IκBα were determined by Western blot. RESULTS: Compared with control group, the protein expression of MMP-2 and NF-κB p65 in the myocardium and the serum content of TNF-α were significantly increased in myocarditis group (P<0.05). The protein expression of IκBα was lower in myocarditis group than that in control group (P<0.05).CONCLUSION: TNF-α, NF-κB p65 and MMP-2 were higher in the mice with acute viral myocarditis. The increased expression of them might be involved in the pathogenesis of viral myocarditis.     

Protective effect of capsaicin on lipopolysaccharide-induced activation of vascular endothelial cells

AIM:To investigate the effect of capsaicin on lipopolysaccharide (LPS)-induced activation of cultured endothelial cells of mouse aorta in vitro. METHODS:The endothelial cells were isolated from mouse aorta and cultured in vitro, and the specific cell markers of the cells were identified by immunofluorescence staining. The cells were stimulated with LPS (100 μg/L) combined with or without capsaicin, and the cells and supernatant were collected at 12 h, 24 h and 48 h. The levels of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1) and soluble P-selectin (sP-selectin) in the supernatant were measured by ELISA. The levels of nuclear NF-κB p65 and cytopasmic p-IκBα and IκBα were detected by Western blotting. RESULTS:Compared with control group, the levels of sP-selectin, sICAM-1 and sVCAM-1 in LPS group were significantly increased (P<0.05), and LPS promoted the expression of sICAM-1 and sVCAM-1 in a time-dependent manner. Compared with LPS group at the same time point, capsaicin inhibited the expression of sP-selectin, sICAM-1 and sVCAM-1 in a dose-dependent manner. Compared with control group, the protein levels of NF-κB p65 and p-IκBα in LPS group at 24 h were significantly increased (P<0.05), while the protein level of IκBα in LPS group at 24 h were significantly decreased (P<0.05). Compared with LPS group, capsaicin decreased the protein levels of NF-κB p65 and p-IκBα and increased the protein level of IκBα in a dose-dependent manner. CONCLUSION: Capsaicin has a protective effect on LPS-induced vascular endothelial cell activation, which potentially contributes to the suppression of IκBα degradation and NF-κB p65 nuclear translocation.     

Endoplasmic reticulum stress is involved in cardiomyocyte apoptosis induced by β1-adrenoceptor autoantibody

AIM: To investigate the role of endoplasmic reticulum (ES) stress in cardiomyocyte apoptosis induced by β₁-adrenoceptor autoantibody (β₁-AA). METHODS: The rat model of active immunization with the second extracellular loop of β₁-adrenoceptor was established, and SA-ELISA was applied to detect the level of β₁-AA in serum of actively immunized rats. The apoptosis of cardiomyocytes was detected by TUNEL staining, and the protein expression levels of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12 in rat heart tissues were determined by Western blot and immunohistochemistry. After purified β₁-AA obtained by affinity chromatography was used to treat H9c2 myocardial cells, the cell viability was measured by CCK-8 assay and the apoptosis was analyzed by flow cytometry with Annexin V-FITC/PI double staining. The H9c2 cells were treated with ER stress inhibitor 4-phenoxybutyric acid (4-PBA) before interfered with β₁-AA, and the changes of cell viability and apoptosis were determined by CCK-8 assay and flow cytometry. RESULTS: Compared with vehicle group, the level of β₁-AA in the serum of rats was significantly increased after active immunization for 2 weeks and further rised in 8 weeks, and increased apoptosis was observed in cardiomyocytes after active immunization for 2 weeks, lasting till 8 weeks. Compared with vehicle group, the protein expression of GRP78, CHOP and caspase-12 increased after active immunization for 4 weeks and 8 weeks. Continuous reduction of cell viability and increased apoptosis of H9c2 cells were induced by β₁-AA. ER stress inhibitor 4-PBA pretreatment in H9c2 cells reversed the increased apoptosis and decreased cell viability induced by β₁-AA, indicating that suppression of ER stress effectively reduced cardiomyocyte apoptosis. CONCLUSION: β₁-AA induces increased apoptosis in cardiomyocytes by activating ER stress.     

Resveratrol attenuates inflammatory pain induced by complete Freund's adjuvant via NF-κB signaling pathway in a mouse model

AIM: To investigate the anti-inflammatory action of resveratrol (Res) and its correlation with nuclear factor-κB (NF-κB) signaling pathway in a mouse model of inflammatory pain.METHODS: BALB/c mice (n=60) were randomly divided into 6 groups:normal control group, inflammatory pain model group, positive control (dexamethasone, 0.5 mg/kg) group and resveratrol (100, 50 and 25 mg/kg) groups (10 mice in each group). In order to observe the anti-inflammatory pain effects of reseratrol on mice, the paw withdrawal mechanical threshold, paw withdrawal thermal latency and cold withdrawal times were detected. In order to analyze the mechanism of analgesic effect of resveratrol, the expression levels of NF-κB, inhibitor of NF-κB (IκB) α, inhibitor of NF-κB kinase (IKK) β, tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the spinal cord tissues (L4~L6) of the mice were determined by RT-PCR and Western blot.RESULTS: The resveratrol at 100 and 50 mg/kg increased the paw withdrawal mechanical threshold, prolonged the paw withdrawal thermal latency, and decreased the cold withdrawal times in the inflammatory pain mice (P<0.05 or P<0.01). The resveratrol at 100 mg/kg down-regulated the mRNA and protein expression levels of NF-κB, IκBα, IKKβ, TNF-α and IL-1β in the spinal cord tissues (L4~L6) of inflammatory pain mice (P<0.05 or P<0.01).CONCLUSION: Resveratrol ameliorates the inflammatory pain of the mice induced by complete Freund's adjuvant. The mechanism is related to the inhibition of NF-κB signaling pathway.     

α7nAChR is involved in anti-inflammation of physiological concentrations of glucocorticoids

AIM: To explore the role of α7 nicotinic acetylcholine receptor (α7nAChR) in anti-inflammation of glucocorticoids (GCs) at physiological concentrations. METHODS: MTT assay was used to measure the viability of BV-2 cells, which were processed by hydrocortisone at different concentrations. On the basis of inflammatory model induced by LPS in BV-2 cells, experimental groups were divided as follows: (1) control; (2) LPS; (3) GCs＋LPS; (4) methyllycaconitine (MLA)＋GCs＋LPS. The levels of TNF-α and IL-1β in the cell supernatants were detected by ELISA. RESULTS: Hydrocortisone at concentrations of 2 000 and 1 000 nmol/L decreased the cell viability to (76.9±5.5)% and (90.8±7.3)%, respectively, indicating the cellular injury by GCs at over-physiological doses. LPS significantly induced the releases of TNF-α and IL-1β in a time- and dose-dependent manner in BV-2 cells. Hydrocortisone at physiological concentrations (500 and 250 nmol/L) reduced the releases of TNF-α and IL-1β in BV-2 cells stimulated by LPS, and MLA at concentration of 10 nmol/L antagonized the anti-inflammatory effect of GCs. CONCLUSION: α7nAChR is involved in the anti-inflammatory effect of the physiological concentrations of GCs.     

LPS-induced hyperpermeability in brain vascular endothelial cell is related to NF-κB signaling

AIM: To investigate the role of nuclear factor kappa B (NF-κB) signaling in the changes of permeability in brain-derived microvascular endothelial (bEnd.3) cells induced by lipopolysaccharide (LPS).METHODS: The bEnd.3 cells were randomly divided into 3 groups: bEnd.3 group, bEnd.3/vector group and bEnd.3/muIκBα group. The cells in the latter 2 groups were transfected with pcDNA3.1hygro and DNMu-IκBα (a dominant-negative mutant of IκB) plasmids, respectively. All the cells were exposed to LPS. The activity of NF-κB, monolayer barrier integrity and F-actin distribution were detected by luciferase reporter assay, transendothelial electrical resistance (TEER) assay and rhodamine-phalloidin staining, respectively. The expression of tight junction proteins (ZO-1 and claudin-5) and phosphorylation of myosin light chain (MLC) were determined using Western blotting.RESULTS: In bEnd.3 group and bEnd.3/vector group, the NF-κB activity began to increase obviously as early as 0.5 h after pretreatment with LPS. LPS decreased TEER, and induced F-actin rearrangement and ZO-1 down-regulation in 3 h. Incubation of the cells with LPS for 12 h induced the most significant disruptive effects on the permeability and tight junctions. Moreover, high expression of phosphorylated MLC accompanied with the early damages of tight junctions was observed. However, these destabilizing alterations were suppressed in bEnd.3/muIκBα group by the inhibition of NF-κB activity.CONCLUSION: LPS induces hyperpermeability in brain microvascular endothelial cells. The functions of NF-κB signaling are related to influencing disruptions of tight junctions by regulating the phosphorylation of MLC.     

Expression of cyclooxygenase-2 in IL-1β-stimulated mesangial cells is medicated by NF-κB/IκB signal pathway

AIM: To investigate the role of NF-κB/IκB signal pathway in the regulation of cyclooxygenase-2 (COX-2) expression in human mesangial cells (HMC). METHODS: The PGE₂ concentration in supernatants of HMC was measured by radioimmunoassay. COX-2 mRNA and protein expression were determined by RT-PCR and Western blot. Electrophoretic mobility shift assay (EMSA) and Western blot were used to detect the activity of NF-κB and degradation of IκB. RESULTS: IL-1β significantly upregulated COX-2 expression and PGE₂ production in HMC. Significant up-regulation of NF-κB activation, nuclear translocation of p65 subunit, and degradation of IκB α and IκB β were observed in IL-1β-induced HMC. CONCLUSION: Expression of COX-2 in IL-1β-induced HMC is mediated by NF-κB/IκB signal pathway.     

Effects of burn sera on IκBα degradation and NF-κB activation in monocytes in vitro

AIM: To investigate the effects of burn sera on IκBα degradation, NF-κB activation in peripheral blood monocytes (PBMCs) in order to explore the role of burn sera on activation of monocytes. METHODS: PBMCs isolated from healthy volunteers were stimulated by sera from healthy volunteers and burn patients and by burn sera together with PDTC (pyrrolidine dithioncarbamate). Activation of monocytic NF-κB was tested by electrophoretic mobility shift assay (EMSA) and the degradation of monocytic IκBα was determined by Western blotting. RESULTS: When compared to that in control group, cytosolic IκBα degradation occurred within 30 min after PBMCs stimulated by burn sera, and peaked at 60 min. But IκBα gradually recovered in the cytoplasm after 2 h of stimulation. Meanwhile, activity of monocytic NF-κB was markedly increased, reached the peak at 30 min to 60 min after stimulation, and gradually decreased after 2 h of stimulation. PDTC (an antioxidants) effectively inhibited the monocytic IκBα degradation and activation of NF-κB induced by burn sera. CONCLUSION: Burn sera might induce the degradation of IκBα, then activate NF-κB, which ultimately lead to the secretion of cytokines from the monocytes.     

Effects of diterpenoid C from ether extract of Radix Curcumae on nuclear factor-κB activity in LPS-induced human gastric adenocarcinoma SGC7901 cells

AIM: To observe the effects of diterpenoid C from ether extract of Radix Curcumae (RC) on the activity of nuclear factor-κB in human gastric adenocarcinoma SGC7901 cells stimulated with lipopolysaccharide (LPS). METHODS: SGC7901 cells were normally cultured, induced by LPS, or treated with LPS plus RC. The protein expression of IKKα, IKKβ, p65, phosphorylated p65 and phosphorylated IκBα was assayed by Western blotting. NF-κB DNA binding activity was determined by electrophoretic mobility shift assay. RESULTS: RC reduced the protein expression of IKKα, IKKβ, p65, phosphorylated p65 and phosphorylated IκBα induced by LPS. NF-κB DNA binding activity increased much greatly by LPS stimulation, while RC resisted the action of LPS. CONCLUSION: RC may attenuate the secretion of inflammatory cytokines by inhibiting the activation of NF-κB signaling pathway.     

Advances in IκB protein family research

IκB is an inhibitor of nuclear factor-kappa B (NF-κB) and presents in the majority of cells. Eight structurally related members of the mammalian IκB family have been described:IκBα, IκBβ, IκBε, Bcl-3, IκBγ, IκBδ, p100 and p105. The ankyrin repeat domain of IκB can interact with NF-κB, and sequester NF-κB in the cytoplasm as inactive complexes. Most recently, IκBα has been found to inhibit p53 tumor suppressor protein by binding p53 to form a cytoplasmic p53·IκBα complex and studies have shown that p100 profoundly sensitizes cells to death-receptor-mediated apoptosis. The current review is to describe the members of IκB family, their related signaling pathways, and their application in tumor therapy.     

1,25-dihydroxyvitamin D3 inhibits nuclear factor kappa B signaling pathway in passively sensitized human airway smooth muscle cells

AIM:To investigate the effects of 1,25-dihydroxyvitamin D3 ［1,25-(OH)2D3］ on nuclear factor kappa B (NF-κB) signaling pathway in passively sensitized human airway smooth muscle cells (HASMCs). METHODS:HASMCs were passively sensitized with 10% serum from asthmatic patients. 1,25-(OH)2D3 was used as an interfering factor. Electrophoretic mobility shift assay (EMSA) was used to detect the DNA-binding activity of NF-κB. Immunocytochemical staining was used to observe the nuclear translocation of NF-κB p65. Western blotting was used for IκBα and phosphorylated IκBα protein detection. Real-time fluorescence quantitative PCR was used to determine vitamin D receptor (VDR), vitamin D 24-hydroxylase (CYP24) and IκBα mRNA expression. The mRNA expression of IκBα in HASMCs after actinomycin D treatment was also determined. RESULTS:(1) 1,25-(OH)2D3 significantly attenuated the DNA-binding activity of NF-κB and the nuclear translocation of NF-κB p65 in HASMCs passively sensitized by asthmatic serum. (2) 1,25-(OH)2D3 enhanced IκBα mRNA stability and inhibited IκBα protein phosphorylation in passively sensitized HASMCs, thus increasing IκBα expression in these HASMCs. (3) 1,25-(OH)2D3 up-regulated VDR mRNA level and evoked its functional response in passively sensitized HASMCs. CONCLUSION: 1,25-(OH)2D3 enhanced the expression of IκBα and therefore inhibited NF-κB signaling passway in HASMCs. This effect may be dependent on VDR, and responsible for the inhibitory effect of 1,25-(OH)2D3 on passively sensitized HASMCs.     

Curcumin reduces neuroinflammation stimulated by Aβ25-35 in primary rat microglial cells

AIM: To investigate the effects of curcumin (Cur) on the expression of High mobility group box 1 protein (HMGB1), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) in amyloid-β (Aβ)-induced primary rat microglial cells. METHODS: Microglia were derived from the cerebral cortices of postnatal rat brains. The cells were identified by immunocytochemistry using mouse anti rat Iba-1 monoclonal antibody. A cell model using primary rat microglial cells incubated with Aβ_25-35 as an inflammation model of Alzheimer's disease (AD) was set up. The morphological characters of primary rat microglial cells were observed. The concentration of Aβ_25-35 and the treatment concentration of curcumin were selected by CCK-8 assay. Cultured primary rat microglial cells were divided into 5 groups:normal cell group, Aβ_25-35 group, Cur group, Aβ_25-35+Cur group and Aβ_25-35+DMSO group. The expression of HMGB1, NF-κB, and receptor for advanced glycation end products (RAGE) was detected by Western blot. The levels of HMGB1, IL-1β, and TNF-α in the culture supernatant were measured by ELISA. RESULTS: The purity of primary microglias determined by Iba-1 immunofluorescence was more than 95%. The protein levels of HMGB1, RAGE and NF-κB were significantly increased after Aβ_25-35 stimulation. After treatment with Cur, the protein levels of HMGB1, RAGE and NF-κB were significantly decreased (P<0.05). The levels of HMGB1, IL-1β and TNF-α in the supernatant were significantly increased after Aβ_25-35 stimulation. Cur significantly decreased the level of HMGB1, IL-1β and TNF-α in the supernatant. CONCLUSION: Curcumin significantly inhibits neuroinflammation stimulated by Aβ_25-35 in primary rat microglial cells.     

Observation of cardiomyocytes stimulated by TNF-α, IL-1β, LPS in vitro

AIM: To observe the changes of cardiomyocytes after stimulation by TNF-α, IL-1β, LPS.METHODS: Cardiac ventricular myocytes were cultured in vitro. Different doses of TNF-α, IL-1β, LPS were added to stimulate the cardiomyocytes, the hypertrophy of cardiomyocytes 8 h, 24 h, and 48 h after stimulation was determined and the apoptosis were also observed 24 h, 48 h, 72 h after stimulation. RESULTS: Compared to the normal myocytes, the cardiomyocytes were hypertrophied after stimulation by 10 μg/L, 15 μg/L of TNF-α, 20 μg/L, 100 μg/L of IL-1β and 10 mg/L, 15 mg/L, 20 mg/L of LPS, and the effect was dose-dependent, the strongest effect was showed in 24 h. Moreover, 20 μg/L of TNF-α, 100 μg/L of IL-1β and 30 mg/L of LPS caused cardiomyocyte apoptosis, especially in 72h. CONCLUSION: TNF-α, IL-1β, LPS induced the cardiomyocyte hypertrophy and apoptosis, suggesting the inflammation may be the main cause of cardiovascular disease.     

DNA microarray profiling to identify norepinephrine-response genes in A7r5 aortic smooth muscle cells

AIM: To define the gene expression changes of vascular smooth muscle cells (VSMCs) in response to norepinephrine (NE). METHODS: The expression adrenergic receptors (AR) were determined by radioligand binding assay in A7r5 cells. Gene expression profiles were identified by cDNA microarray after A7r5 cells were treated with NE for 24 h, and mRNA expressions of α_1A-AR and α_1B-AR were confirmed by real-time PCR. RESULTS: α₁-AR and β-AR existed in A7r5 cells. Seventy-five genes with changed expression in response to NE were screened out. These genes are involved in cell structure, cell/organism defense, metabolism, signal transduction and so on. α_1A-, α_1B-AR mRNA expression identified by microarray and realtime quantitive PCR displayed similar patterns. CONCLUSIONS: Gene expression profile in response to NE was analyzed comprehensively with the microarray technique. NE induces many kinds of different function genes in A7r5 cells, which may provide a novel insight into the particular role of NE that modulates multiple aspects of biological function in VSMCs.     

Effect of recombinant rat CC16 protein on LPS-induced expression of TNF-α, IL-6 and IL-8 in rat tracheal epithelial cells

AIM: To explore the effect of recombinamt rat CC16 protein (rCC16) on LPS-induced expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and IL-8 in the rat tracheal epithelial (RTE) cells.METHODS: The RTE cells were incubated with rCC16 at concentrations of 0.5, 1.0 and 2.0 mg/L in serum-free media for 2 h prior to LPS (0.1 mg/L) treatment for further 24 h. The cells were harvested for assessing the mRNA levels of TNF-α, IL-6 and IL-8 by RT-qPCR. The cell culture supernatants were collected for analyzing the protein levels of TNF-α, IL-6 and IL-8 by ELISA. In addition, the nuclear translocation of nuclear factor-κB (NF-κB) p65 was tested by Western blot.RESULTS: rCC16 inhibited LPS-induced IL-6 and IL-8 expression at both mRNA and protein levels in the RTE cells in a concentration-dependent (0~2 mg/L) manner, as demonstrated by RT-qPCR and ELISA. However, no concentration-dependent manner between the dose of rCC16 and TNF-α expression was observed, and rCC16 inhibited LPS-induced TNF-α expression at lower concentration (0.5 mg/L). rCC16 concentration-dependently inhibited the effects of LPS on the level of nuclear translocation of NF-κB p65.CONCLUSION: rCC16 suppresses LPS-mediated TNF-α, IL-6 and IL-8 production through inactivation of NF-κB activity in RTE cells.[KEY WORDS] CC16 protein; Airway inflammation; LPS; Inflammatory mediators; Nuclear factor-κB