Mechanisms of hypoxia-induced tumor necrosis factor-α production in rat alveolar macrophages

AIM: To study the effect of hypoxia inducible factor-1 alpha (HIF-1α) on tumor necrosis factor alpha (TNF-α) production in rat alveolar macrophages cultured under hypoxic condition. METHODS: Using HIF-1α decoy inhibiting its function, Immunohistochemistry, Western blot, semiquantitative RT-PCR and ELISA were used to determine the expression of HIF-1α protein and mRNA and the production of TNF-α in rat alveolar macrophages cultured under hypoxic condition (3% O2, 5% CO2, 92% N2), respectively. RESULTS: Expression of HIF-1α was positive in cultured macrophage nucleoli in hypoxia group and HIF-1α decoy group but it was negative in nomoxic control group. The content of HIF-1α protein in hypoxia group and HIF-1α decoy group were significantly higher than that in nomoxic control group (P<0.05). The content of HIF-1α mRNA in hypoxia group and HIF-1α decoy group were markedly higher than that in nomoxic control group (P<0.05), respectively. The content of TNF-α in hypoxia group (115±17 ng/L) was higher than that in control group ［（69±13） ng/L, P<0.05］ and HIF-1α decoy group ［（81±15） ng/L, P<0.05］. CONCLUSION: Hypoxia can increase significantly expression and activity of HIF-1α， which can promote the production of TNF-α in rat alveolar macrophages. It suggests that HIF-1α plays an important role in the pathogenesis of chronic inflammation-related diseases that can give rise to lung hypoxia such as COPD.     

Role of IL-33/ST2 signaling pathway in fibrosis diseases

Interleukin (IL)-33 is a member of IL-1 family. It is identified as a functional ligand for ST2 which is an IL-1 receptor-like protein. IL-33/ST2 signaling is involved in T-cell-mediated immune responses. Increasing evidence indicates that IL-33 has different roles in different diseases. Recently, some studies have demonstrated that IL-33 may be related to the genesis and development of fibrosis diseases. We review current knowledge of the biological characteristics of IL-33 and the role of IL-33/ST2 signaling pathway in fibrosis diseases.     

Effect of recombinant interleukin-13 on 3T3 fibroblasts in vitro

AIM: To investigate the influence and mechanism of recombinant interleukin-13 (rIL-13) on fibroblasts. METHODS: 3T3 fibroblasts were divided into two groups: the treated group was treated with rIL-13 (80 μg/L, 24 h or 48 h) and the control was without rIL-13 treatment. Transmission electron microscope and Hoechst kit were used to observe morphology of 3T3 fibroblasts in both groups. The activity of proliferation in both groups was investigated and compared by MTT means. Western blot was used to analyze the level of collagen type I induced by rIL-13 in fibroblasts. The levels of IL-6 and IL-8 in the culture supernatants were determined by radioimmunoassay. RESULTS: The more ribosomes and mitochondrions, as well as bigger nuclei were found in the treated group. The production of IL-6 and IL-8, and proliferation ratio of fibroblasts treated with rIL-13 for 24 h or 48 h were increased obviously, compared with the control (P<0.01). The expression of collagen type I protein in treated groups was also significantly higher than that in control (P<0.01). CONCLUSION: rIL-13 upregulates the proliferation of fibroblasts. rIL-13 also has an effect on the production of proinflammatory factors and collagen type I. Taken together, these results suggest that IL-13 may play important roles in the pathogenesis of tissue fibrosis.     

Altered T cell signaling events caused by anti-CD4 monoclonal antibody in suppressing experimental autoimmune cardiomyopathy

AIM:We examined the efficacy of anti-L3T4 McAb in the T cell signaling pathway in treating experimental autoimmune cardiomyopathy in BALB/c mice, as a model of the autoimmune mechanism involved in human dilated cardiomyopathy (DCM). METHODS:ADP/ATP carrier peptides were used to induce autoimmune cardiomyopathy in BALB/c mice. After 3 months, anti-L3T4 McAb was administered to deplete CD4+ T cells in the mice. Real-time PCR were used to detect the expression of intracellular signaling molecules (p56lck, p59fyn and Zap-70) and cytokine production (IFN-γ, IL-2 and IL-4) in T cells. The expression of CD45 was determined by immunohistochemistry analysis. RESULTS:Reduced expression of p56lck, p59fyn and Zap-70 and the reduced cytokine production of IFN-γ, IL-2 and IL-4 in T cells of anti-L3T4-treated DCM mice were found. Also, the expression of CD45 in spleen T cells was significantly decreased in the anti-L3T4-treated group. In contrast, immunization with irrelevant Ab did not protect the mice, the expression of T cell signaling molecules, CD45, and cytokine were not inhibited. CONCLUSION:These studies provide direct evidence that anti-L3T4 McAb can be an effective immunomodulator to T cell signal molecules and subsequent cytokine production events in ADP/ATP carrier-induced DCM in BALB/c mice.     

Establishment of human lung infection model in vitro and mechanisms of NTHi-induced inflammatory responses

AIM: To investigate the key signal pathways of inflammatory responses in lung tissues induced by the infection of nontypeable Haemophilus influenzae(NTHi). METHODS: Human lung tissues were co-incubated with NTHi (10¹⁰ CFU/L) for 4 h and 24 h, respectively. The phosphorylation of p38 mitogen-activated protein kinase (MAPK) was detected by Western blotting. The nuclear translocation of nuclear factor (NF)-κB was examined by electrophoretic mobility shift assay (EMSA). The expression of Toll-like receptor (TLR) 2 was measured by real-time quantitative RT-PCR, and the level of interleukin (IL)-8 was detected by enzyme-linked immunosorbent assay (ELISA). Furthermore, lung tissues were incubated with anti-TLR2 monoclonal antibody (5 mg/L), p38 MAPK inhibitor SB203580 (20 μmol/L), or NF-κB inhibitor PDTC (25 μmol/L) for 2 h, then stimulated with NTHi (10¹⁰ CFU/L) for another 24 h. The supernatants were collected for IL-8 detection. RESULTS: The TLR2-p38 MAPK-NF-κB signaling pathway in lung tissues was rapidly activated 4 h after NTHi stimulation. IL-8 secreted from lung tissues infected with NTHi was significantly increased compared with uninfected lungs (P<0.05). The pre-incubation with anti-TLR2 antibody, p38 MAPK inhibitor or NF-κB inhibitor markedly decreased IL-8 production induced by NTHi. CONCLUSION: NTHi induces inflammatory responses in lung tissues by activation of TLR2-p38 MAPK-NF-κB signaling pathway. Human lung infection model provides a new research tool for the study of interaction between pathogens and hosts.     

Effects of NF-κB "decoy" oligodeoxynucleotides on TNF-α and IL-6 expression in LPS-induced mouse macrophages

AIM: To study the effect of NF-κB "decoy" oligodeoxynucleotides on TNF-α and IL-6 expression in LPS-induced mouse macrophages. METHODS: Mouse macrophage cell line J774.1 cells were cultured with LPS and liposome-mediated oligodeoxynucleotides, and the levels of TNF-α and IL-6 measured in the different culture supernatant by enzyme linked immunosorbent assay. RNA was extracted from macrophages, and the mRNA expression of TNF-α and IL-6 in macrophages was observed by RT-PCR. RESULTS: NF-κB "decoy" oligodeoxynucleotides decreased the expression of TNF-α and IL-6 in LPS-induced macrophages and inhibited generation of TNF-α and IL-6. The level of TNF-α and IL-6 did not change in control group. CONCLUSIONS: NF-κB "decoy" oligodeoxynucleotides inhibit the expression of TNF-α and IL-6 in LPS-induced macrophages, which is probably due to the specific inhibition of activated NF-κB binding sites .     

Effects of interleukin -13 on interleukin-12 production in mesangial cells induced by LPS

AIM: To investigate the effect of interleukin-13 (IL-13) on interleukin-12 (IL-12) production in mesangial cells.METHODS: The protein synthesis of IL-12 in mesangial cells was measured by ELISA.The expression of IL-12 mRNA in mesangial cells was evaluated by RT-PCR.RESULTS: The production of IL-12 in mesangial cells stimulated by lipopolysaccharide(LPS) was significantly increased (P<0.01).IL-13 (1-100 μg/L) inhibited the protein and mRNA expression of IL-12 in a dose-dependent manner (P<0.05 or P<0.01).CONCLUSION: IL-13 inhibits IL-12 expression induced by LPS in mesangial cells.IL-13 may regulate immune responses by balancing Th1/Th2 in glomerulonephritis.     

Effects of NF-κB decoy oligonucleotides on apoptosis in lung cancer cell A549

AIM: To investigate the effects of NF-κB decoy oligodeoxynucleotides (ODNs) on apoptosis in lung cancer cell A549. METHODS: The treatments of lung cancer cells (A549) were divided into three groups: group A (control group); group B (decoy ODN group) and group C (scramble decoy ODN group). FITC-labeled NF-κB decoy ODNs was transfected into A549 with LipofectAMINE^TM2000. The activation was observed by electrophoretic mobility shift assays (EMSA). The proliferation was observed by growth curve. The apoptosis of cells were observed by flow cytometry and TdT mediated dUTP-biotin Nick End Labeling (TUNEL). The expression of Bcl-2 and Fas were observed by Western blot. RESULTS: After FITC-labeled decoy ODNs was transfected for 1 hour, the decoy ODNs was detected in the nuclei of A549 cells. EMSA performed the depression of the NF-κB binding to the nucleus. The growth curve showed the inhibition of the A549 cell growth and the percentage of apoptosis was increased compare with control group by flow cytometry and TUNEL. The amount of apoptosis inhibitor (Bcl-2) in group A and group C were 2.0 times and 2.1 times more than that in group B, respectively. The level of apoptosis accelerator (Fas) in group B were 2.6 times and 2.3 times more than that in group A and group C, respectively via Western blot. CONCLUSION: The NF-κB decoy ODNs accelerate the apoptosis of lung cancer cell A549 and the mechanism may be due to its inhibiting the expression of Bcl-2 and increasing the level of Fas.     

Effects of CpG ODN on dendritic cells and its mechanisms

Oligodeoxynucleotide containing unmethylated cytosine phosphate-guanosine motif(CpG ODN) may induce high expression of CD80, CD86, CD83, HLA I and HLAⅡ molecules on dendritic cells(DC) and stimulate DC to produce high level of IL-6, IL-12, TNF-α and IFN-α. CpG ODN is demonstrated in vivo to be a very potent adjuvant for Th1 cells, regulating Th0 cells to develop toward Th1 cells. Its role for DC is characteristics of CpG ODN sequence specificity and species specificity. CpG ODN is, at present, considered as a pathogen associated molecular pattern which binds its specific receptor，Toll-like receptor 9，then functions through TLR/IL-1R signaling pathway. It may represent a new therapeutic drug for broad applications in infectious disease, autoimmune disease, allergy and cancer therapy.     

Inhibitory effect of NF-κB decoy ODN on expressions of TLR4 and IL-8 in LPS- induced intestinal epithelial cells

AIM: To study the effect of NF-κB decoy oligodeoxynucleotides(ODNs) on TLR4 and IL-8 expression in LPS-induced SW480 cells. METHODS: SW480 cells were cultured in vitro and stimulated for 3 h with LPS (10 μg/L). NF-κB decoy oligodeoxynucleotides mediated by lipofectin 2000 were added into the cell culture for 6 h. The supernatants were collected and messured for IL-8 by ELISA. TLR4 mRNA and IL-8 mRNA were examined by RT-PCR, respectively. The results were compared with control group, Scrambled ODNs group and lipofectin 2000 group. RESULTS: After SW480 cells were stimulated by LPS, TLR4 mRNA, IL-8 mRNA and IL-8 expressions were significantly increased, and the difference compared with control group was obvious. After treated with NF-κB decoy oligodeoxynucleotides, TLR4 mRNA, IL-8 mRNA and IL-8 expressions were significantly inhibited. The Scrambled ODNs group and lipofectin 2000 group had no effect on them. CONCLUSION: NF-κB decoy ODNs will become a new gene drug for treating inflammatory bowel disease(IBD).     

Delaying aging of AMPK by inhibiting NLRP3 inflammasome

AMP-activated protein kinase (AMPK) is a central regulator of many metabolic pathways involved in the pathophysiological processes of aging and related diseases, and has become an important integrator influencing inflammation (including inflammasome). The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome has recently become a highly concerned marker of stress and metabolic risk. It is associated with neurodegenerative and cardiovascular diseases and type 2 diabetes mellitus. However, the signal pathways regulating NLRP3 inflammasome have not yet been clarified. Studies have shown that many AMPK-dependent signaling pathways, such as autophagy (including mitophagy) and endoplasmic reticulum stress (ERS), regulate the expression of NLRP3 inflammasome during aging. Inhibiting the expression of NLRP3 seems to be a common factor in many complex-mediated aging responses. Therefore, eliminating the common triggers of autophagy/ERS and NLRP3 inflammasome, and suppressing the signal cascade of inflammatory cytokines such as IL-1β and TNF-α, will be an important research direction to explore new anti-aging strategies.     

Effects of specific immunotherapy on allergic rhinitis children accompanied with asthma

AIM: To explore the effects of Dermatophagoides pteronyssinus allergen-specific immunotherapy (SIT) on the serum interleukin (IL)-13,IL-4,interferon (IFN)-γ, nasal symptoms and pulmonary functions in allergic rhinitis children accompanied with asthma. METHODS: Fifty-eight cases of allergic rhinitis children accompanied with asthma participated in this study. Their allergens were Dermatophagoides pteronyssinus. Thirty-five children received SIT were SIT group, and the other 23 children received local glucocorticoid treatment were medical group. The serum levels of IL-13, IL-4 and IFN-γ were examined, and the nasal symptoms and pulmonary functions were checked before treatment and one year after treatment. RESULTS: There was a significant difference in nasal symptoms between the two groups one year after treatment (P<0.05). The patients in SIT group had fewer symptoms. The serum levels of IL-4 and IL-13 were clearly reduced. IFN-γ and the ratio of IFN-γ/IL-4 were significantly increased (P<0.05). The pulmonary functions were significantly improved in SIT group (P<0.05). Meanwhile in medical group, the serum levels of IL-4 and IL-13 had less change (P>0.05), and the pulmonary functions were poorly improved (P>0.05). CONCLUSION: SIT may regulate the imbalance of Th1/Th2 cells in allergic rhinitis accompanied with asthma by reducing the serum levels of IL-4 and IL-13 and increasing IFN-γ and the ratio of IFN-γ/IL-4, resulting in reducing the nasal symptoms and improving the pulmonary functions.     

IL-12 induces T lymphocytes underging apoptosis and affects the expression and signal conduction of Bcl-2

AIM: IL-12 acts upon T lymphocytes and activates its receptor complexes of β1/β2 ,and so IL-12 can regulate TH1/TH2 balance. Our study is aimed at IL-12-inducing apoptosis of T cells and expression and signal conduction of Bcl-2 during T cell apoptosis. METHODS: The apoptosis of T cells was detected by Annexin V staining cytometry and the expression of Bcl-2 under different inhibitors were detected by the method of semi-quantitative PCR. RESULTS: IL-12 can induce the human leukemic T cell line(TIB-152) and the human lymphoma T cell line(HTB-176) and the normal human T cells to undergo apoptosis. The Bcl-2 expression at 6 hours of treatment with IL-12 increased aparently, and reached the max at 24 hours. But IL-12 did influence Bcl-2 expression. IL-12 can induce T cells to undergo apoptosis which is characterized by early membrane changes. CONCLUSION: The inducing effect is correlated with the concentration of IL-12 and the maturation of T cells. Bcl-2 takes part in the progression of T cells' apoptosis as a apoptosis mediator.     

Effect of curcumin on ox-LDL-induced HAEC injury

AIM: To investigate the effect of curcumin on oxidized low-density lipoprotein (ox-LDL)-induced injury of human aortic endothelial cells (HAECs). METHODS: HAECs were pre-treated with curcumin at different concentrations and then treated with ox-LDL. The cell viability was assessed by MTT assay. The cell proliferation ability was analyzed by EdU assay. ELISA was used to determine the concentrations of interleukin-6 (IL-6), transforming growth factor β1 (TGFβ1), high mobility group box-1 protein (HMGB1) and secretory receptor for advanced glycation end products (sRAGE) in the HAEC culture medium. The binding activity of peroxisome proliferator-activated receptor γ (PPARγ) was evaluated by electrophoretic mobility shift assay. The protein levels of HO-1, HMGB1, RAGE,IL-6,TGFβ1 and phosphorylated PPARγ in the HAECs were determined by Western blot. RESULTS: The viability and the proliferation ability decreased significantly in the HAECs treated with ox-LDL. The PPARγ/HO-1 signaling pathway was inhibited while its down-stream HMGB1/RAGE signaling pathway was activated by ox-LDL. The levels of IL-6, TGFβ1, HMGB1 and sRAGE were increased. Pre-treatment with curcumin activated PPARγ/HO-1 signaling pathway and inhibited HMGB1/RAGE signaling pathway in ox-LDL treated HAECs in a concentration-dependent manner. The levels of IL-6, TGFβ1, HMGB1 and sRAGE were also decreased dramatically by pre-treatment of curcumin in a concentration-dependent manner. CONCLUSION: ox-LDL induces HAEC damage by inhibiting PPARγ/HO-1 to activate HMGB1/RAGE inflammatory signaling. Curcumin exerts protective effect on ox-LDL treated HAECs via activating PPARγ/HO-1 signaling pathway.     

IL-12 induces T lymphocytes apoptosis and influences the expression and signal transduction of Fas/FasL

AIM: IL-12 acts upon Tlymphocytes and activates its receptor complexes of β1/β2,and so IL-12 can regulate TH1/TH2 balance. Our study is aimed at IL-12-inducing apoptosis of Tcells and expression and signal transduction of Fas/FasLduring Tcell apoptosis. METHODS: The apoptosis of Tcells was detected by Annexin Vstaining cytometry and the expression of Fas/FasLunder different inhibitors were detected by semi-quantitative PCR. RESULTS: IL-12 induced the human leukemic Tcell line(TIB-152) and the human lymphoma Tcell line(HTB-176) and the normal human Tcells to undergo apoptosis. The FasLexpression at 6 hours after treatment with IL-12 increased apparently, and reached the max at 24 hours, and FasLexpression induced by IL-12 was inhibited by PKCinhibitor. But IL-12 did not influence Fas expression. CONCLUSIONS: IL-12 can induce Tcells to undergo apoptosis which is characterized by early membrane changes, the inducing effect is correlated with the concentration of IL-12 and the maturation of Tcells. FasLparticipates in the progression of Tcell apoptosis as a apoptosis mediator, and the effect of IL-12 on FasLexpression may be related with PKCpathway.     

TCRVβ7.1 transfection activates signal protein ERK and insreases IFN-γ expression in PBMCs

AIM: To investigate the effect of tumor-specific T cell receptor (TCR) gene transfection on production of cytokine and signaling activation in T cells.METHODS: TCRVβ7.1 gene was transferred into peripheral blood mononuclear cells (PBMCs) obtained from healthy adults, and the expression of Vβ7.1 was detected by flow cytometry before and after transfection. The total quantities of protein and phosphorylation of ERK1/2 were detected by Western blotting. The expressions of IL-4 and IFN-γ were detected by ELISA.RESULTS: The results of flow cytometry showed that TCRVβ7.1 protein was efficiently expressed after transfection. The phosphorylation level of ERK increased significantly in TCRVβ7.1-modified PBMCs, and was related with the activation of T cells. The expression of IFN-γ was significantly higher in TCR-transfected cells than that in non-transfected cells. The expression of IL-4, however, has no distinct difference between groups.CONCLUSION: The transfection of TCRVβ7.1 induces phosphorylation of ERK1/2 and production of IFN-γ, and activates T lymphocytes.