ABSTRACT
Cigarette smoke (CS) exposure is the predominant risk factor for the development of chronic obstructive pulmonary disease (COPD) and the third leading cause of death worldwide. We aimed to elucidate whether mitochondrial respiratory inhibition and oxidative stress are triggers in its etiology. In different models of CS exposure, we investigated the effect on lung remodeling and cell signaling of restoring mitochondrial respiratory electron flow using alternative oxidase (AOX), which bypasses the cytochrome segment of the respiratory chain. AOX attenuated CS-induced lung tissue destruction and loss of function in mice exposed chronically to CS for 9 months. It preserved the cell viability of isolated mouse embryonic fibroblasts treated with CS condensate, limited the induction of apoptosis, and decreased the production of reactive oxygen species (ROS). In contrast, the early-phase inflammatory response induced by acute CS exposure of mouse lung, i.e., infiltration by macrophages and neutrophils and adverse signaling, was unaffected. The use of AOX allowed us to obtain novel pathomechanistic insights into CS-induced cell damage, mitochondrial ROS production, and lung remodeling. Our findings implicate mitochondrial respiratory inhibition as a key pathogenic mechanism of CS toxicity in the lung. We propose AOX as a novel tool to study CS-related lung remodeling and potentially to counteract CS-induced ROS production and cell damage.
Subject(s)
Cigarette Smoking/adverse effects , Mitochondria/metabolism , Mitochondrial Proteins/genetics , Nicotiana/adverse effects , Oxidoreductases/genetics , Plant Proteins/genetics , Pulmonary Disease, Chronic Obstructive/genetics , Animals , Apoptosis/drug effects , Cell Movement/drug effects , Complex Mixtures/pharmacology , Disease Models, Animal , Electron Transport Chain Complex Proteins/genetics , Electron Transport Chain Complex Proteins/metabolism , Embryo, Mammalian , Female , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/enzymology , Gene Expression , Lung/drug effects , Lung/enzymology , Lung/physiopathology , Macrophages/drug effects , Macrophages/metabolism , Macrophages/pathology , Mice , Mice, Transgenic , Mitochondria/drug effects , Mitochondria/pathology , Mitochondrial Proteins/metabolism , Neutrophils/drug effects , Neutrophils/metabolism , Neutrophils/pathology , Oxidative Stress , Oxidoreductases/metabolism , Plant Proteins/metabolism , Primary Cell Culture , Pulmonary Disease, Chronic Obstructive/chemically induced , Pulmonary Disease, Chronic Obstructive/enzymology , Pulmonary Disease, Chronic Obstructive/physiopathology , Reactive Oxygen Species/agonists , Reactive Oxygen Species/antagonists & inhibitors , Reactive Oxygen Species/metabolism , Signal Transduction , Nicotiana/chemistryABSTRACT
The role that estrogens play in the aging lung is poorly understood. Remodeling of the aging lung with thickening of the alveolar walls and reduction in the number of peripheral airways is well recognized. The present study was designed to address whether estrogen deficiency would affect age-associated changes in the lungs of female C57BL/6J mice. Lungs isolated from old mice (24 months old, estrogen-deficient) demonstrated decreased lung volume and decreased alveolar surface area. There was no difference in alveolar number in the lungs of old and young mice (6 months old, estrogen-replete). Estrogen replacement restored lung volume, alveolar surface area, and alveolar wall thickness to that of a young mouse. Estrogen receptor-α (ERα) protein expression increased without a change in ERß protein expression in the lung tissue isolated from old mice. In the lungs of old mice, the number of apoptotic cells was increased as well as the activation of matrix metalloproteinase-2 and ERK. Young mice had the highest serum 17ß-estradiol levels that decreased with age. Our data suggest that in the aging female mouse lung, estrogen deficiency and an increase of ERα expression lead to the development of an emphysematous phenotype. Estrogen replacement partially prevents these age-associated changes in the lung architecture by restoration of interalveolar septa. Understanding the role of estrogens in the remodeling of the lung during aging may facilitate interventions and therapies for aging-related lung disease in women.
Subject(s)
Aging/physiology , Estradiol/therapeutic use , Estrogen Replacement Therapy , Lung Diseases/drug therapy , Lung/drug effects , Aging/metabolism , Animals , Apoptosis/drug effects , Estradiol/pharmacology , Estrogen Receptor alpha/genetics , Estrogen Receptor alpha/metabolism , Female , Lung/metabolism , Lung/pathology , Lung Diseases/metabolism , Lung Diseases/pathology , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 2/metabolism , Mice , Mice, Inbred C57BL , Organ Size/drug effects , Ovariectomy , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
Chondrocytes are important for the development and maintenance of articular cartilage. However, both in osteoarthritis (OA) and rheumatoid arthritis (RA) chondrocytes are involved in the process of cartilage degradation and synthesize important immunomodulatory mediators, including nitric oxide (NO) generated by the inducible NO synthase (iNOS). To uncover the role of iNOS in the pathomechanisms of OA and RA, we analyzed the regulation of iNOS expression using immortalized human chondrocytes as a reproducible model. In C-28/I2 chondrocytes, iNOS expression was associated with the expression of the chondrocyte phenotype. Peak induction by a cytokine cocktail occurred between 6 and 8h and declined by 24h. Inhibition of p38MAPK, NF-kappaB and the JAK2-STAT-1alpha pathways resulted in a reduction of iNOS expression. In contrast to other cell types, the cytokine-mediated induction of the human iNOS promoter paralleled the induction rate of the iNOS mRNA expression in C-28/I2 chondrocytes. However, in addition post-transcriptional regulation of iNOS expression by the RNA binding protein KSRP seems to operate in these cells. As seen in other chondrocyte models, glucocorticoids were not able to inhibit cytokine-induced iNOS expression in C-28/I2 cells, due to the lack of the glucocorticoid receptor mRNA expression. In this model of glucocorticoid-resistance, the new fungal anti-inflammatory compound S-curvularin was able to inhibit cytokine-induced iNOS expression and iNOS-dependent NO-production. In summary, we demonstrate for the first time that differentiated human immortalized C-28/I2 chondrocytes are a representative cell culture model to investigate iNOS gene expression in human joint diseases.
Subject(s)
Chondrocytes/enzymology , Gene Expression Regulation, Enzymologic/genetics , Nitric Oxide Synthase Type II/genetics , RNA Processing, Post-Transcriptional/genetics , Anti-Inflammatory Agents/pharmacology , Cartilage, Articular/drug effects , Cartilage, Articular/enzymology , Cell Line, Transformed , Chondrocytes/drug effects , Cytokines/pharmacology , Enzyme Induction , Gene Expression Regulation, Enzymologic/drug effects , Humans , Interferon-Stimulated Gene Factor 3/antagonists & inhibitors , Janus Kinase 2/antagonists & inhibitors , NF-kappa B p50 Subunit/antagonists & inhibitors , Nitric Oxide Synthase Type II/biosynthesis , RNA Processing, Post-Transcriptional/drug effects , RNA, Messenger/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Receptors, Glucocorticoid/genetics , Receptors, Glucocorticoid/metabolism , Trans-Activators/genetics , Trans-Activators/metabolism , Zearalenone/analogs & derivatives , Zearalenone/pharmacology , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitorsABSTRACT
Nitroglycerin (NTG) and pentaerithrityl tetranitrate (PETN) are organic nitrates used in the treatment of angina pectoris, myocardial infarction, and congestive heart failure. Recent data show marked differences in the effects of NTG and PETN on the generation of reactive oxygen species. These differences are attributed to different effects of NTG and PETN on the expression of antioxidative proteins like the heme oxygenase-I. To analyze the expressional effects of NTG and PETN in a more comprehensive manner we performed whole genome expression profiling experiments using cardiac total RNA from NTG- or PETN-treated rats and DNA microarrays containing oligonucleotides representing 27,044 rat gene transcripts. The data obtained show that NTG and PETN together significantly modify the expression of >1,600 genes (NTG 532, PETN 1212). However, the expression of only a small group of these genes (68) was modified by both treatments, indicating marked differences in the expressional effects of NTG and PETN. NTG treatment resulted in the enhanced expression of genes that are believed to be markers for cardiotoxic processes. In addition, NTG treatment reduced the expression of genes described to code for cardioprotective proteins. In sharp contrast, PETN treatment enhanced the expression of cardioprotective genes and reduced the expression of genes believed to perform cardiotoxic effects. In conclusion, our data suggest that NTG treatment results in the induction of cardiotoxic gene expression networks leading to an activation of mechanisms that result in pathological changes in cardiomyocytes. In contrast, PETN treatment seems to activate gene expression networks that result in cardioprotective effects.
