Background Previous discovery that long-term administration of pentoxifylline （PTX） to mice chronically exposed to smoke led to the development of pulmonary fibrosis rather than emphysema initiated our curiosity on ...Background Previous discovery that long-term administration of pentoxifylline （PTX） to mice chronically exposed to smoke led to the development of pulmonary fibrosis rather than emphysema initiated our curiosity on whether the Wnt/β-catenin pathway, a set of signaling proteins essential to organ development and lung morphogenesis in particular were activated in the pathogenesis of pulmonary fibrosis. Methods Male BALB/c mice were randomized into four study groups： Group Sm, smoke exposure and taken regular forage; Group PTX, no smoke but taken PTX-rich forage; Group Sm＋PTX, smoke exposure and taken PrX-rich forage; Group control： shamed smoke exposure and taken regular forage. Animals were sacrificed at day 120. Morphometry of the lung sections and the expressions of TGF-β1, hydroxyproline, β-catenin, cyclin D1, T cell factor 1 （Tcf-1） and lymphoid enhancer factor 1 （Lef-1） mRNA, etc, in the lung homogenate or in situ were qualitatively or quantitatively analyzed. Results As expected, smoke exposure along with PTX administration for 120 days, lungs of the mice progressed to be a fibrosis-like phenotype, with elevated fibrosis score （3.9±1.1 vs. 1.7±0.6 in Group Sm, P 〈0.05）. TGF-β1（pg/g） （1452.4±465.7 VS. 818.9±2.02.8 in Group Sm, P 〈0.05） and hydroxyproline （mg/g） （5.6±0.6, vs. 2.4±0.1 in Group Sm, P 〈0.05） were also consistently increased. The upregulation of β-catenin measured either by counting the cell with positive staining in microscopic field （17.4±7.9 vs. 9.9±2.9 in Group Sm, P 〈0.05） or by estimation of the proportion of blue-stained area by Masson＇s trichrome （11.8±5.6 vs. 4.7±4 in Group Sm） in Group SM＋PTX was much more noticeable as than those in Group Sm. The expression of β-catenin measured by positive cell counts was correlated to TGF-β1 concentration in lung tissue （r=0.758, P 〈0.001）. PTX per se caused neither fibrosis nor emphysema though expression of β-catenin and downstream gene cyclin D1 may also be altered by this medication. Conclusions PTX mediated transformation of pulmonary emphysema into pulmonary fibrosis under chronic cigarette smoke exposure is associated with upregulation of β-catenin and elevation of TGF-β1, implying that activation of Wnt/β-catenin signaling may be involved in the pathogenesis of pulmonary fibrosis.展开更多
Background Cigarette smoke-induced emphysema is associated with overexpression of the chemokine receptor CXCR3 and its ligands. Previously, we have demonstrated that pentoxifylline （PTX） alleviated cigarette smoke-i...Background Cigarette smoke-induced emphysema is associated with overexpression of the chemokine receptor CXCR3 and its ligands. Previously, we have demonstrated that pentoxifylline （PTX） alleviated cigarette smoke-induced emphysema. The aim of this study was to determine if the overexpression of CXCR3 and its ligand interferon-inducible protein-10 （IP-10） that was elicited by smoke exposure were attenuated by PTX. Methods （1） The study in vitro： a given number of RAW264.7 macrophages with decreasing concentrations of PTX in the culture medium were challenged with cigarette smoke extract （CSE）; （2） The study in vivo： male BALB/c mice were randomized into four groups, i.e., sham-smoke, smoke only, smoke with 2 mg/kg PTX, and smoke with 10 mg/kg PTX. The smoke exposure time was 90 minutes once a day, 6 days a week for 16 weeks. PTX was given intraperitoneally before each episode of smoke exposure. Interferon （IFN）-y and IP-10 in broncho-alveolar lavage fluid （BALF） and in culture medium were measured by enzyme-linked immunosorbent assay （ELISA）. IP-10 mRNA in lung tissue was assessed by RT-PCR. CXCR3 positive cells in lung sections were visualized by immunochemistry staining. Results Up-regulation of IFN-γ and IP-10 in the culture medium of macrophages elicited by CSE was inhibited by PTX in a dose-dependent manner. Chronic cigarette smoke exposure led to overexpression of IFN-γ and IP-10 in BALF, upregulation of IP-10 mRNA and increased infiltration of CXCR3^＋ cells into lung parenchyma. Administration of PTX decreased the level of IFN-y from （6.26±1.38） ng/ml to （4.43±0.66） ng/ml by low dose PTX or to （1.74±0.28） ng/ml by high dose PTX. IP-10 was reduced from （10.35±1.49） ng/ml to （8.19±0.79） ng/ml by low dose PTX or to （7.51±0.60） ng/ml by high dose PTX. The expression of IP-10 mRNA was also down-regulated （P 〈0.05）. But only with a high dose of PTX was the ratio of CXCR3^＋ cells decreased; 15.2±7.3 vs. 10.4±1.8 （P 〈0.05）. Conclusion PTX attenuates cigarette smoke-induced overexpression of chemokine receptor CXCR3 and its ligand IP-10, which is relevant to its inhibitory effect on pulmonary emphysema.展开更多
基金This study was supported by a grant from Natural Science Foundation of Hubei Province, China （No. 2008cdb153）.Acknowledgements： We are grateful to Prof. NIE Xiu in the Department of Pathology of this hospital for her valuable advices and devoting efforts on pathological analysis in this study.
文摘Background Previous discovery that long-term administration of pentoxifylline （PTX） to mice chronically exposed to smoke led to the development of pulmonary fibrosis rather than emphysema initiated our curiosity on whether the Wnt/β-catenin pathway, a set of signaling proteins essential to organ development and lung morphogenesis in particular were activated in the pathogenesis of pulmonary fibrosis. Methods Male BALB/c mice were randomized into four study groups： Group Sm, smoke exposure and taken regular forage; Group PTX, no smoke but taken PTX-rich forage; Group Sm＋PTX, smoke exposure and taken PrX-rich forage; Group control： shamed smoke exposure and taken regular forage. Animals were sacrificed at day 120. Morphometry of the lung sections and the expressions of TGF-β1, hydroxyproline, β-catenin, cyclin D1, T cell factor 1 （Tcf-1） and lymphoid enhancer factor 1 （Lef-1） mRNA, etc, in the lung homogenate or in situ were qualitatively or quantitatively analyzed. Results As expected, smoke exposure along with PTX administration for 120 days, lungs of the mice progressed to be a fibrosis-like phenotype, with elevated fibrosis score （3.9±1.1 vs. 1.7±0.6 in Group Sm, P 〈0.05）. TGF-β1（pg/g） （1452.4±465.7 VS. 818.9±2.02.8 in Group Sm, P 〈0.05） and hydroxyproline （mg/g） （5.6±0.6, vs. 2.4±0.1 in Group Sm, P 〈0.05） were also consistently increased. The upregulation of β-catenin measured either by counting the cell with positive staining in microscopic field （17.4±7.9 vs. 9.9±2.9 in Group Sm, P 〈0.05） or by estimation of the proportion of blue-stained area by Masson＇s trichrome （11.8±5.6 vs. 4.7±4 in Group Sm） in Group SM＋PTX was much more noticeable as than those in Group Sm. The expression of β-catenin measured by positive cell counts was correlated to TGF-β1 concentration in lung tissue （r=0.758, P 〈0.001）. PTX per se caused neither fibrosis nor emphysema though expression of β-catenin and downstream gene cyclin D1 may also be altered by this medication. Conclusions PTX mediated transformation of pulmonary emphysema into pulmonary fibrosis under chronic cigarette smoke exposure is associated with upregulation of β-catenin and elevation of TGF-β1, implying that activation of Wnt/β-catenin signaling may be involved in the pathogenesis of pulmonary fibrosis.
基金This study was supported by a grant from the Natural Science Foundation of Hubei Province, China （No. 2008cdb 153）. The authors have no conflict of interest to declare.Acknowledgements： We are grateful to Dr. TIAN Yuan, Surgery Laboratory of Union Hospital, Tongji Medical College for his generous donation of the macrophage cell line and guidance on cell culture. We also thank Prof. WU Ping and Ms. O1oo Stella Anne for their assistance on revision of this manuscript.
文摘Background Cigarette smoke-induced emphysema is associated with overexpression of the chemokine receptor CXCR3 and its ligands. Previously, we have demonstrated that pentoxifylline （PTX） alleviated cigarette smoke-induced emphysema. The aim of this study was to determine if the overexpression of CXCR3 and its ligand interferon-inducible protein-10 （IP-10） that was elicited by smoke exposure were attenuated by PTX. Methods （1） The study in vitro： a given number of RAW264.7 macrophages with decreasing concentrations of PTX in the culture medium were challenged with cigarette smoke extract （CSE）; （2） The study in vivo： male BALB/c mice were randomized into four groups, i.e., sham-smoke, smoke only, smoke with 2 mg/kg PTX, and smoke with 10 mg/kg PTX. The smoke exposure time was 90 minutes once a day, 6 days a week for 16 weeks. PTX was given intraperitoneally before each episode of smoke exposure. Interferon （IFN）-y and IP-10 in broncho-alveolar lavage fluid （BALF） and in culture medium were measured by enzyme-linked immunosorbent assay （ELISA）. IP-10 mRNA in lung tissue was assessed by RT-PCR. CXCR3 positive cells in lung sections were visualized by immunochemistry staining. Results Up-regulation of IFN-γ and IP-10 in the culture medium of macrophages elicited by CSE was inhibited by PTX in a dose-dependent manner. Chronic cigarette smoke exposure led to overexpression of IFN-γ and IP-10 in BALF, upregulation of IP-10 mRNA and increased infiltration of CXCR3^＋ cells into lung parenchyma. Administration of PTX decreased the level of IFN-y from （6.26±1.38） ng/ml to （4.43±0.66） ng/ml by low dose PTX or to （1.74±0.28） ng/ml by high dose PTX. IP-10 was reduced from （10.35±1.49） ng/ml to （8.19±0.79） ng/ml by low dose PTX or to （7.51±0.60） ng/ml by high dose PTX. The expression of IP-10 mRNA was also down-regulated （P 〈0.05）. But only with a high dose of PTX was the ratio of CXCR3^＋ cells decreased; 15.2±7.3 vs. 10.4±1.8 （P 〈0.05）. Conclusion PTX attenuates cigarette smoke-induced overexpression of chemokine receptor CXCR3 and its ligand IP-10, which is relevant to its inhibitory effect on pulmonary emphysema.
