title: Inspiratory resistive breathing induces MMP-9 and MMP-12 expression in the lung.
abstract: Inspiratory resistive breathing (IRB) is characterized by large negative intrathoracic pressures and was shown to induce pulmonary inflammation in previously healthy rats. Matrix metalloproteinases (MMP)-9 and -12 are induced by inflammation and mechanical stress in the lung. We hypothesized that IRB induces MMP-9 and -12 in the lung. Anesthetized, tracheostomized rats breathed spontaneously through a two-way valve, connected to an inspiratory resistance, with the tidal inspiratory tracheal pressure set at 50% of the maximum. Quietly breathing animals served as controls. After 3 and 6 h of IRB, respiratory mechanics were measured, bronchoalveolar lavage (BAL) was performed, lung injury score was estimated, and lung MMP-9 was estimated by zymography and ELISA. MMP-9 and MMP-12 immunohistochemistry was performed. Isolated normal alveolar macrophages were incubated with BAL from rats that underwent IRB. After 18 h, MMP-9 and -12 levels were measured in supernatants, and immunocytochemistry was performed. Macrophages were treated with IL-1β, IL-6, or TNF-α, and MMP-9 in supernatants was measured. After 6 h of IRB, leukocytes in BAL increased, and IL-1β and IL-6 levels were elevated. Elasticity and injury score were increased after 3 and 6 h of IRB. Lung MMP-9 levels increased after 6 h of IRB. MMP-9 and MMP-12 were detected in alveolar macrophages and epithelial (bronchial/alveolar) cells after 3 and 6 h of IRB. MMP-9 and MMP-12 were found in supernatants after treatment with 6 h of IRB BAL. Cytosolic immunostaining was detected after treatment with 3 and 6 h of IRB BAL. All cytokines induced MMP-9 in culture supernatants. In conclusion, IRB induces MMP-9 and -12 in the lung of previously healthy rats.
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Toumpanakis
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Olga
authors.initials: O
authors.lastname: Noussia
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Ioanna
authors.initials: I
authors.lastname: Sigala
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Eleni
authors.initials: E
authors.lastname: Litsiou
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Loverdos
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Zacharatos
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Karavana
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Tatiana
authors.initials: T
authors.lastname: Michailidou
authors.affiliation: Department of Pathology, General Hospital "Evangelismos", Athens, Greece.
authors.forename: Christina
authors.initials: C
authors.lastname: Magkou
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece;
authors.forename: Zongmin
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: First Department of Pathology, University of Athens, Medical School, Athens, Greece;
authors.forename: Stamatios
authors.initials: S
authors.lastname: Theocharis
authors.affiliation: Department of Critical Care and Pulmonary Services and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos Hospital, University of Athens, Medical School, Athens, Greece; tvassil@med.uoa.gr.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Vassilakopoulos
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004417:Dyspnea / Q000201:enzymology*; D004790:Enzyme Induction; D005260:Female; D008168:Lung / Q000201:enzymology*; D016676:Macrophages, Alveolar / Q000201:enzymology; D053508:Matrix Metalloproteinase 12 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D021381:Protein Transport; D017208:Rats, Wistar; D012119:Respiration
chemical_list: D020780:Matrix Metalloproteinase 9; D053508:Matrix Metalloproteinase 12
keywords: inflammation; metalloproteinases; resistive breathing