Therapeutic effects of hypobaric hypoxia on asthma in guinea pigs

AIM:To explore the mechanismof the therapeutic effect of hypobaric hypoxia on allergic asthmas guinea pigs.METHODS:After the model of asthma was established with oval bumin(OA)challenge i n OA sensitized guinea pigs,the ani mals were randomized i nto the asthmas group(AG),the alleviative group(ALG)and hypobaric hypoxiatreated group(HHTG).The levels of plasma cortisol and endothelin(ET),ET in bronchoalveolar lavage fl ui d(BALF)were deter mi ned by radioi mmunoassay.The pul monary pathological changes were observed with optical microscope.RESULTS:(1)Infiltration of eosinophils(EOS)in alveolar septumwas found in AGand ALG,while it was re-duced in HHTG.(2)The level of plasma cortisol was significantly higher in AGthanin normal control group(NCG)(P<0.01).But it was significantly lower in ALGthani n NCG(P<0.01),there was no difference in plasma cortisol level between HHTG and NCG.(3)The content of ET in plasma was significantly higher in ALGthanthat i n NCG,AG and HHTG(P<0.01),and ET level in BALF was significantly higher in AG than that in NCG,ALG and HHTG(P<0.05),however,no significant difference was found among the latter three groups, respectively.CONCLUSION:After the treatment with hypobaric hypoxia,the ET levels of the plasma and BALF were decreaced and the content of plasma cortisol was increaced,and infiltration of EOS in alveolar septum was decreaced in asthmatic gui nea pigs.That may be one of the mechanisms by which hypobavic hypoxia prevents and cures asthma.     

Effects of Foxp3 transfection on splenocyte functions in asthma mice

AIM: To study the expression and the effects of Foxp3 on the immunologic functions by transfecting the Foxp3 eukaryotic expression plasmid into the splenocytes of the asthma mice. METHODS: The mice were sensitized and challenged by ovalbumin to make asthma model. The splenocytes were harvested and cultured. The Foxp3 expression vector pcDNA3.1(-)-Foxp3 was transfected into the splenocytes with electroporation. The splenocytes transfected with empty vector and control splenocytes (non-transfected) were also set up. The expression of Foxp3 at mRNA and protein levels was detected by RT-PCR and Western blotting, respectively. The proportion of CD4⁺CD25⁺ Treg cells/CD4⁺ cells was measured by flow cytometry. Proliferation of the splenocytes was analyzed with MTT assay. ELISA was used to determine the levels of interleukin 4 (IL-4) and interferon γ (IFN-γ) in the supernatant of the splenocytes. RESULTS: The expression of Foxp3 at mRNA and protein levels in transfection group was significantly higher than that in empty vector group and control group. The proportion of CD4⁺CD25⁺Treg cells/CD4⁺ cells in transfection group was higher than that in empty vector group and control group. The proliferation of transfected cells was markedly inhibited compared with empty vector group and control group. The levels of IL-4 and IFN-γ were significantly lower in transfection group than those in empty vector group and control group. CONCLUSION: The transfected Foxp3 gene overexpresses in the splenocytes of asthma mice. Foxp3 increases the number of CD4⁺CD25⁺ T cells and inhibits the proliferation and production of Th1/Th2 cytokines in splenocytes.     

Effects of mitogen activated protein kinase on γ-glutamylcysteine synthase in lung of guinea pigs with bronchial asthma

AIM: To investigate the effects of mitogen activated protein kinase on γ-glutamylcysteine synthase (γ-GCS) in lung of guinea pigs with bronchial asthma.METHODS: Twenty adult male guinea pigs were divided into asthmatic group and control group (10 in each group).Asthmatic model was established by ovalbumin intraperitoneal injection combined with inhalation.The numbers of total and inflammation cells in bronchoalveolar lavage fluid (BALF) were measured.The γ-GCS-h mRNA in lung tissue was examined by in situ hybridization and RT-PCR.Immunohistochemistry was used to detecte the expression of γ-GCS,phosphorylated extracellular signal regulated kinase (p-ERK),phosphrylated c-Jun amino terminal kinase (p-JNK) and phosphorylated p38 (p-p38) in lung tissues.Western blotting was conducted to determine the expressions of p-ERK,p-JNK and p-p38 in lung tissue.The activity of γ-GCS was measured by coupled enzyme assay.RESULTS: (1) The total cell number and number of eosinophils in BALF of asthmatic group were significantly higher than those in control group (P<0.01).(2) Immunohistochemistry indicated that the p-ERK,p-p38,p-JNK and γ-GCS were stronger expressed in asthmatic group than those in control group (P<0.01).Western blotting also discovered that the expressions of p-ERK,p-JNK and p-p38 in lung tissue of asthmatic group were stronger than those in control group.(3) Both in situ hybridization and RT-PCR analysis showed that the expression of γ-GCS-h mRNA was more positive in asthmatic group compared with control group (P <0.01).(4) The activity of γ-GCS of asthmatic group was significantly higher than that in control group (P<0.01).(5) Linear correlation analysis indicated that in lung tissue of guinea pig with asthma,p-ERK and p-p38 markedly positive correlated with γ-GCS-h mRAN and γ-GCS protein.No relationship between p-JNK and γ-GCS-h mRAN,γ-GCS protein was observed.CONCLUSION: The expressions of p-ERK,p-p38,p-JNK and γ-GCS increase in lung of guinea pigs with bronchial asthma.p-ERK and p-p38 may positively regulate the expression of γ-GCS.     

Effects of dexamethasone on intracellular expression of TH1/TH2 cytokines in experimental asthma mice

AIM: To study the effects of dexamethasone (DXM) on intracellular expression of T_H1/T_H2 cytokines and the mechanism of that during the development of asthma. METHODS: Eighteen BALB/c mice were divided into 3 groups at random: control group, asthma group, and DXM treated group, with 6 mice in each. The expressions of T-box expressed in T cells (T-bet) and GATA-binding protein-3 (GATA-3) in lung tissue were detected by Western blotting. The expressions of intracellular cytokines interleukin-4 and interferon-γ in CD4⁺ T cell were measured by flowcytometry.RESULTS: The results of flow cytometry indicated that the ratio of intracellular cytokines IL-4/IFN-γ in CD4⁺ T cells in asthma group was much higher than that in control group (P<0.01), the ratio of intracellular IL-4/IFN-γ in T cells in DXM group was lower than that in asthma group significantly (P<0.01). The expression of T-bet in lung tissue in asthma group was lower than that in control group significantly (P<0.01), while GATA-3 was higher than that in control group significantly (P<0.01). The expressions of T-bet and GATA-3 in DXM group were much lower than those in asthma group (P<0.01), but the decreased degree of GATA-3 was more than that of T-bet. CONCLUSION: With pathological process of asthma, to reverse the ratio of IL-4/IFN-γ in CD4⁺ T cell by regulating T-bet and GATA-3 expression can improve the inflammatory reaction and may be one of the mechanisms of DXM in treating asthma.     

Dynamic observation of asthma model induced by allergen in mice from acute inflammation to chronic remodeling

AIM: To dynamically observe and compare the relative changes of the indexes from the process of acute inflammation to chronic remodeling in asthmatic mice induced by ovalbumin (OVA).METHODS: Female BALB/c mice (n=60) were randomly divided into normal control group and asthma group. The mice in asthma group were sensitized and challenged by OVA, while the mice in normal group received equal volume of normal saline (NS). The challenge was performed for 3 consecutive days from the 21th day to observe the response of acute inflammation, and then the mice in different groups were challenged once per week for 5 weeks. Detailed comparisons of the dynamic changes of cell infiltration, cytokine expression and airway remodeling were conducted.RESULTS: Compared with NS group, the mice in OVA group showed a predominantly eosinophilic infiltration into the airway lumen, increased production of Th2-type cytokines, secretion of epithelial mucus and deposition of subepithelial collagen. In OVA challenge groups, the levels of inflammatory cells and inflammatory factors were remarkably higher in 24 d group, whereas the most obvious changes of goblet cell hyperplasia and airway remodeling were observed in 52 d group.CONCLUSION: Acute asthma model is sufficiently induced by 3 consecutive days of OVA challenge protocol, which is accompanied with high levels of inflammatory cells and inflammatory factors. The OVA challenge protocol once per week for 5 weeks could induce a chronic asthma model with obvious airway remodeling.     

Effects of hypoxia inhalation therapy on the number of eosinophil and CD4+T-lymphocyte in remission stage in asthmatic guinea pigs

AIM:To explore the mechanism underlying the therapeutic effects of hypoxia inhalation on asthma. METHODS:Guinea pigs were randomized into the normal group(NG), asthmatic group(AG) and the hypoxia inhalation-treated group(HITG). The model of asthma was established in the latter two groups through sensitization and induction with 10% ovalbumin(OA) and 1% OA, respectively. The animals in HITG were treated with hypoxia inhalation (13.0%±0.5% O₂/N₂ mixed gas). The content of serum cortisol, the number of eosinophils(EOS) and percentage of hypodense eosinophils(HEOS) in bronchoalveolar lavage fluid(BALF),the number of CD₄⁺T-lymphocyte in peripheral blood(PB) and the tension of airway muscle were determined. RESULTS:(1)The content of serum cortisol was significantly higher in NG and HITG than in AG(P＜0.01); (2)The number of EOS and percentage of HEOS in BALF was significantly lower in HITG than in AG(P＜0.01); (3) The number of CD₄⁺T-lymphocyte in PB was significantly higher in AG than in HITG(P＜0.01).CONCLUSION:After treatment with hypoxia inhalation, the content of serum cortisol in asthmatic guinea pigs was significantly increased to result in marked decreased of the number of EOS, the percentage of HEOS in BALF, and the number of CD₄⁺T-lymphocyte in PB, thus result in the tension of airway muscle and alleviation of the airway hyperresponsiveness. All these may be beneficial to preventing the relapse of asthma.     

Role of calcineurin in airway remodeling in guinea pig model of asthma

AIM:To investigate the role of calcineurin (CaN) in airway remodeling in guinea pig model of asthma.METHODS:Male guinea pigs were randomly divided into three groups: control, asthma group and CsA group. The following parameters were measured: 1. The protein content, cell count and differential count of BALF; 2. The amount of [³H]-TdR incorporation into central airway smooth muscle; 3. The mean thickness of airway wall and airway smooth muscle of small airwaysl; 4.CaN activity of trachea and lung tissue.RESULTS:1. The protein content, cell count and eosinophil of BALF in CsA group were 46%, 51% and 60% lower than those in asthma group, respectively (P＜0.01); 2. [³H]-TdR incorporation in CsA group was 22% lower than that in asthma group (P＜0.05);3. The mean thickness of airway wall and airway smooth muscle were 34% and 37% less in CsA group than those in asthma group, respectively (P＜0.01); 4. CaN activity of lung tissue and trachea were 52% and 44% lower in CsA group than those in asthma group, respectively (P＜0.01).CONCLUSION:CsA reduced airway remodeling in guinea pig model of asthma, indicating the role of CaN in the airway remodeling.     

Determination of T cell cycle and the expression of bcl- 2 in asthmatic mice and its significance

AIM: To investigate the changes of T cell cycle, the expression of bcl- 2 in allergic asthmatic mice and the effects of dexamethasone on them. METHODS: An animal model with asthma was established by means of ovalbumin sensitizing-challenging. CD3 expression in spleen and lymphocytes in bronchoalveolar lavage fluid (BALF), T cell cycle and Bcl-2 expression in spleen were detected by flow cytometry. RESULTS: In BALF lymphocytes and spleen lymphocytes, CD3 expression rate in the asthmatic group was significantly higher than that of control group. In BALF lymphocytes, CD3 expression rate in the asthma plus dexamethasone group was significantly lower than that of the asthmatic group. However, in spleen lymphocytes, CD3 expression rate in the asthma plus dexamethasone group was significantly higher than that of the asthmatic group. In spleen lymphocytes, the cell count in S phase, G₂+M phase and apoptosis rate of T cell from the asthmatic group were significantly higher than that from the control group. Cell count in S phase, G₂+M phase and apoptosis rate of T cell from the asthmaplus dexamethasone group was significantly lower than that from the asthmatic group. The Bcl-2 expression rate of T cell from the asthmatic group was significantly higher than that from the control group. CONCLUSIONS: In the allergic asthmatic mice model, T cell count, proliferation and activation of T cells, apoptosis rate of T cells in spleen lymphocytes increase, meanwhile bcl- 2 expression also increases significantly. There was no significant effect of dexamethasone on the bcl- 2 expression. The therapeutic effects of dexamethasone on asthma may be not due to the inhibition of the bcl- 2 expression in T cells.     

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.     

Effects of CpG-oligodeoxynucleotides and dexamethasone on airway remodeling and expression of MMP-9 and TIMP-1 in murine model of chronic asthma

AIM: To observe the changes of airway inflammation and remodeling in a murine model of chronic asthma with CpG- oligodeoxynucleotides(CpG ODN) and dexamethasone (DXM) treatments.METHODS: BALB/c mice were sensitized and repeatedly challenged with ovalbumin.Pathological slides were prepared from left lung and stained with hematoxylin-eosin.WAmus (smooth muscle area),Wamuc (mucous area) and WAi (inner wall area) of the airway were measured and standardized by Pbm (basement membrane perimeter). The areas of collagen Ⅰand Ⅲ in the lung tissue were determined by using a Sirius red-polarizing microscopy morphometry method.Expressions of matrix metalloprotease-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were detected by immunohistochemistry.RESULTS: WAmus/Pbm,WAmuc/Pbm and WAi/Pbm decreased significantly in CpG ODN and DXM treated group when compared with asthma group (P<0.05).No statistical significance between CpG ODN and DXM treated group was observed (P>0.05).Collagen deposition in asthma group increased more than that in CpG ODN and DXM treated group (P<0.05).The expressions of MMP-9 and TIMP-1 were much higher in asthma group than those in CpG ODN and DXM treated group (P<0.05).It had no statistical significance between CpG ODN and DXM treated group (P>0.05).CONCLUSION: Airway remodeling occurrs in the chronic asthma.Early intervention with steroid or CpG might partially inhibit its process via lowering expressions of MMP-9 and TIMP-1 in chronic asthma.     

Effect of Toll-like receptor 4 signal transduction on airway inflammation in infant asthmatic rat

AIM: To study the change and regulatory mechanism of Toll-like receptor 4 (TLR4) on eosinophil (EOS) apoptosis. METHODS: Twenty-seven SD rats were randomly divided into control group (A), asthma group (B) and dexamethasone group (D). Asthmatic model rats were sensitized and repeatedly exposed to aerosolized ovalbumin. Pulmonary tissues were observed under light microscope (LM). The inflammatory cells in BALF were counted. The levels of IL-10 in serum were measured by ELISA. Expressions of TLR4 mRNA were tested by hybridization. The apoptotic EOS was detected by TUNEL.RESULTS: (1) LM showed that inflammatory cells infiltrated around the bronchus, airway mucous plug in group B, obviously lightened in group D. (2) Inflammatory cells count in BALF: the total cellular score, EOS absolute count and EOS% in group B were significantly increased (P<0.01). Compared to group B, a significant decrease in group D was observed (P<0.01). (3) The level of IL-10 in group B was significantly higher than that in group A and in group D (P<0.01). (4) No significant difference (P>0.05) of TLR4 mRNA expression was observed between group A and group B. However, that in group D were significantly increased (P< 0.01). (5) Percentages of apoptotic EOS in group B were significantly lower than those in group A (P<0.01), those in group D were significantly increased (P<0.01). A significant correlation between TLR4 mRNA and apoptotic EOS (r=0.612, P<0.01) was observed. CONCLUSION: Dexamethasone can increase IL-10 secretion, induce EOS apoptosis, which may correlate with TLR4 signal transduction.     

Role of GATA-3 in the pathogenesis of airway inflammation in a rat asthma model

AIM: To investigate the role of GATA-3 in the pathogenesis of airway inflammation in a Wistar rat asthma model. METHODS: The Wistar rat asthma model was made with conventional method and animals were divided into five groups (10 rats in each group): asthma group (A group), dexamethasone group (D group), antisense oligonucleotide group (AS group), nonsense oligonucleotide group (NS group) and normal control group (N group). Antisense, nonsense oligonucleotide were administered intranasally, and the dexamethasone was injected intraperitoneally. The airway inflammation was observed with HE staining method. The GATA-3 positive cells were stained immunohistochemically. The GATA-3 mRNA expression in pulmonary tissue was investigated with RT-PCR. The GATA-3 protein in pulmonary tissue was detected by Western blotting. RESULTS: In contrast to N group, the expression of GATA-3 mRNA, protein and the amount of inflammatory cells in pulmonary tissue in group A were increased significantly (P<0.01) and were decreased evidently in group AS and D (P<0.01). The expression of GATA-3 mRNA, protein and the amount of inflammatory cells in NS group were obviously increased compared with those in gropu AS and D (P<0.01). The expression of GATA-3 was related to the amount of eosinophils (r=0.995). CONCLUSION: GATA-3 antisense oligonucleotide blocks the expression of GATA-3 gene and the infiltration of eosinophils. GATA-3 plays an important role in the effector phase of allergic airway inflammation in a Wistar rat asthma model.     

Effects of FGF-21 and Nrf2 on BLM-induced pulmonary fibrosis in mice

AIM:To investigate the effect of fibroblast growth factor-21 (FGF-21) on bleomycin (BLM)-induced inflammatory response and oxidative stress in the lung, and to further explore the molecular mechanism of FGF-21 against pulmonary fibrosis. METHODS:The lung fibrosis model was induced by BLM intratracheal instillation. A total of 40 mice were randomly divided into control group, BLM group, FGF-21 (1, 2 and 5 mg/kg)+BLM groups. Western blot was used to detected the protein expression of collagen I, fibronectin and nuclear factor E2-related factor 2 (Nrf2). The reactive oxygen species (ROS) production was measured by DCFH-DA staining. The levels of inflammatory cytokines were measured by ELISA. The content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx), and the content of hydroxyproline (HYP) were detected by commercially available assay kits. RESULTS:Treatment with FGF-21 notably attenuated BLM-induced the expression levels of inflammatory mediators tumor necrosis factor-α, interleukin-1β and interleukin-6 in the lung tissue. In addition, FGF-21 treatment remarkably reduced the generation of ROS and the content of MDA trigged by BLM, accompanied with the enhanced activity of anti-oxidative enzymes SOD and GPx (P<0.05). Furthermore, treatment with FGF-21 obviously reduced the extracellular matrix (ECM) accumulation by suppressing the expression of collagen I and fibronectin induced by BLM, accompanied with the decreases in the levels of TGF-β1 and HYP. Silencing of Nrf2 expression abolished the protective effect of FGF-21. CONCLUSION:FGF-21 relieves BLM-induced pulmonary fibrosis by reducing the inflammatory response, mitigating oxidative damage and decreasing the ECM deposition via Nrf2 activation, thus providing the basis for the therapeutic effect of FGF-21 on the lung fibrosis.     

Effects of 5-HT and electrolytes on the airway remodeling of bronchial asthma in guinea pigs

AIM: To explore the effects of 5-HT and electrolytes on the airway remodeling in guinea pigs with bronchial asthma.METHODS: 70 guinea pigs were divided into 7 groups: control group, model group, continued model group, 5-HT group, anti-5-HT group, high Mg2+ group, low Mg2+ group.Remodeling model was established with ovalbumin.RESULTS: ① In model group, 5-HT of serum and thickness of airway walls were significantly increased compared with control group (P<0.05,P<0.01).② In continued model group, 5-HT and thickness of airway walls were significantly increased compared with model group (P<0.05, P<0.01).③ In 5-HT group, thicknesses of airway walls were significantly increased compared with continued model group (P<0.05).④ In anti-5-HT group, thicknesses of airway walls were significantly decreased compared with continued model group (P<0.05).⑤ In high Mg2+ group, thicknesses of airway walls were significantly decreased compared with continued model group (P<0.05).⑥ In low Mg2+ group, thickness of airway smooth muscle was significantly increased compared with continued model group (P<0.05).⑦ With the aggravation or alleviation of airway remodeling, concentration of Ca2+ in serum was upward or downward.However, concentration of PO3-4 was downward or upward.⑧ Veriety of Na+, K+, Cl- was no significant difference among groups.⑨ Concentration of 5-HT in serum was corrected with that of Ca2+.CONCLUSIONS: ① 5-HT mediates airway remodeling of asthma in guinea pigs whereas Mg2+ may play a regulatory role.② Increase in Ca2+ and decrease in PO3+4 may promote the airway remodeling of asthma whereas Na+, K+, Cl- may not play any role.③ Concentration of 5-HT in serum was corrected with that of Ca2+ in airway remodeling of asthma.     

Effect of BCG on experimental asthma in a guinea pigmodel of allergen sensitization

AIM: To examine the effect of bacillus calmette-guerin (BCG) on experimental asthma in guinea pigs. METHODS: Guinea pigs were sensitized with BCG and then with ovalbumin (ip). Two weeks later, guinea pigs were challenged with ovalbumin (OVA) aerosol inhalation. Thirty one Guinea pigs were divided into three groups at random control group,OVA-treated group, BCG and OVA-treated group.RESULTS: Ovalbumin inhalation caused a marked airway infiltration of eosinophils and all the animals exhibit asthmatic symptoms. Pretreatment with BCG induced typical increase in lymphocytes and monocytes in peripheral blood and in bronchoalveolar lavage fluid (BALF). BCG markedly inhibited eosinophil infiltration and attenuated the asthmatic symptoms. CONCLUSION: These data suggest that BCG exerts an inhibitory effect on asthmatic inflammation.     

Effects of Wnt/β-catenin signal pathway on asthma airway remodeling

AIM: To explore the effect of Wnt/β-catenin signaling pathway in airway smooth muscle cells (ASMC) on asthmatic airway remodeling.METHODS: The asthmatic airway remodeling model in rats was established and the ASMC was isolated and cultured. The protein expression of β-catenin, glycogen synthase kinase-3β (GSK-3β), c-Myc and cyclin D1 in the ASMC was determined by Western blot. After depressing the interaction between β-catenin and p300/CBP, the cell activity was measured by CCK-8 assay and the change of cell cycle distribution was analyzed by flow cytometry. Meanwhile, the protein expression of c-Myc and cyclin D1 in the ASMC was determined by Western blot after inhibiting P38 mitogen-activated protein kinase (MAPK) activity.RESULTS: The protein levels of β-catenin, c-Myc and cyclin D1 were significantly increased in asthma group while the protein level of GSK-3β was decreased in the same group (P<0.05). After depressing the interaction between β-catenin and p300/CBP, the cell activity of ASMC was decreased in asthma group compared with control group (P<0.05), and the change of the cell cycle distribution in asthma group was also more obvious (P<0.05). After inhibiting P38 MAPK activity, the protein levels of c-Myc and cyclin D1 were all decreased compared with control group in ASMC asthma and control rats (P<0.05).CONCLUSION: Wnt/β-catenin signaling pathway may participates in airway remodeling in asthma by increasing the protein expression of c-Myc and cyclin D1, reacting with the P38 MAPK signaling pathway and regulating the growth of ASMC.     

Effects of PFOA exposure on inflammatory mediators IL-4, IFN-γ and glucocorticoid receptor in asthmatic mice

AIM: To investigate the effects of perfluorooctanoic acid (PFOA) exposure on the changes of asthmatic mouse airway inflammation, inflammatory mediators interleukin-4 (IL-4) and interferon-γ (IFN-γ) in serum, and glucocorticoid receptor (GR) expression in the lung tissue.METHODS: BALB/c mice (n=30) were randomly divided into 5 groups:normal control (C) group, asthma (A) group, asthma+low-dose PFOA (AP10) group, asthma+ mode-rate-dose PFOA (AP50) group and asthma+high-dose PFOA (AP100) group. Asthma model and PFOA exposure model of mice were established according to the grouping. The animals were sacrificed and their lungs were collected for HE staining, transmission electron microscopy, Western blot and immunohistochemical staining. ELISA was applied to detect the levels of IL-4 and IFN-γ in the serum.RESULTS: HE staining of the lungs showed that the asthmatic mice, compared with the normal control mice, had obvious mucus secretion around the airways and infiltration of inflammatory cells around airways and blood vessels, and the effects were much more marked in AP groups. Ultrastructural alteration of the lung tissues in the asthmatic mice were indicated by transmission electron microscopy. Compared with C group, the results of ELISA in A group and AP groups proved that IL-4 in the serum was increased and IFN-γ was decreased significantly (P<0.05). Compare with A group, IL-4 was significantly increased and IFN-γ was decreased in AP100 group (P<0.05), and no difference of those between AP10 group and AP50 group was found. The results of Western blot indicated that GR protein expression in the asthmatic mice were decreased compare with the normal mice (P<0.05), and no difference of that among A group and AP groups was observed. Immunohistochemical staining manifested that GR protein was mainly located in the cytoplasm of bronchial columnar epithelial cells, airway smooth muscle cells and vascular smooth muscle cells.CONCLUSION: Acute airway PFOA exposure in asthmatic mice dose-dependently exacebates lung inflammation by inducing Th2 type immune responses, promotes infiltration of inflammatory cells and mucus secretion around the airways and blood vessels, and destroys the ultrastructure of the lung tissues.     

Lipoxin A4 reduces lipopolysaccharide-induced expression of cyclooxygenase 2 and prostaglandin E2 in human bronchial epithelial cells

AIM: To explore the effects of lipoxin A₄ on the expression of cyclooxygenase 2 (COX-2) in human bronchial epithelial cells (HBECs). METHODS: HBECs were incubated with various concentrations (0.1, 1 and 10 mg/L) of lipopolysaccharide(LPS) for 9 h, or 1 mg/L LPS for different time (3 h, 6 h and 9 h). The levels of COX-2 mRNA in HBECs and prostaglandin E₂ (PGE₂) in the culture supernatant were measured. In addition, the HBECs were exposed to lipoxin A₄ at concentration of 0, 100 and 400 μmol/L after stimulated with LPS at concentration of 1 mg/L for 9 h, and the supernatant of the culture cells was collected for determining the content of PGE₂ by ELISA. The cells were also harvested, and the mRNA and protein levels of COX-2 were analyzed by RT-PCR and Western blotting, respectively. RESULTS: LPS increased the mRNA expression of COX-2 and production of PGE₂ in a dose and time dependent manners in HBECs. Induction of COX-2 mRNA and protein by LPS were inhibited by lipoxin A₄ in a dose-dependent manner. Lipoxin A₄ also significantly decreased LPS-induced production of PGE₂. CONCLUSION: Lipoxin A₄ down-regulates LPS-induced expression of COX-2 and consequently inhibits the production of PGE₂ in HBECs.