ABSTRACT
Limitations on tissue proliferation capacity determined by telomerase/apoptosis balance have been implicated in pathogenesis of idiopathic pulmonary fibrosis. In addition, collagen V shows promise as an inductor of apoptosis. We evaluated the quantitative relationship between the telomerase/apoptosis index, collagen V synthesis, and epithelial/fibroblast replication in mice exposed to butylated hydroxytoluene (BHT) at high oxygen concentration. Two groups of mice were analyzed: 20 mice received BHT, and 10 control mice received corn oil. Telomerase expression, apoptosis, collagen I, III, and V fibers, and hydroxyproline were evaluated by immunohistochemistry, in situ detection of apoptosis, electron microscopy, immunofluorescence, and histomorphometry. Electron microscopy confirmed the presence of increased alveolar epithelial cells type 1 (AEC1) in apoptosis. Immunostaining showed increased nuclear expression of telomerase in AEC type 2 (AEC2) between normal and chronic scarring areas of usual interstitial pneumonia (UIP). Control lungs and normal areas from UIP lungs showed weak green birefringence of type I and III collagens in the alveolar wall and type V collagen in the basement membrane of alveolar capillaries. The increase in collagen V was greater than collagens I and III in scarring areas of UIP. A significant direct association was found between collagen V and AEC2 apoptosis. We concluded that telomerase, collagen V fiber density, and apoptosis evaluation in experimental UIP offers the potential to control reepithelization of alveolar septa and fibroblast proliferation. Strategies aimed at preventing high rates of collagen V synthesis, or local responses to high rates of cell apoptosis, may have a significant impact in pulmonary fibrosis.
Subject(s)
Animals , Male , Apoptosis/physiology , Collagen Type V/biosynthesis , Idiopathic Pulmonary Fibrosis/pathology , Pulmonary Fibrosis/pathology , Telomerase/metabolism , Butylated Hydroxytoluene , Cell Proliferation , Collagen Type I/analysis , Collagen Type II/analysis , Collagen Type V/analysis , Disease Models, Animal , Epithelial Cells/metabolism , Epithelial Cells/pathology , Fluorescent Antibody Technique , Fibroblasts/metabolism , Fibroblasts/pathology , Hydroxyproline/analysis , Immunohistochemistry , In Situ Nick-End Labeling , Mice, Inbred BALB C , Microscopy, Electron , Pulmonary Alveoli/pathology , Pulmonary Alveoli/ultrastructure , Staining and Labeling , Telomerase/isolation & purificationABSTRACT
Limitations on tissue proliferation capacity determined by telomerase/apoptosis balance have been implicated in pathogenesis of idiopathic pulmonary fibrosis. In addition, collagen V shows promise as an inductor of apoptosis. We evaluated the quantitative relationship between the telomerase/apoptosis index, collagen V synthesis, and epithelial/fibroblast replication in mice exposed to butylated hydroxytoluene (BHT) at high oxygen concentration. Two groups of mice were analyzed: 20 mice received BHT, and 10 control mice received corn oil. Telomerase expression, apoptosis, collagen I, III, and V fibers, and hydroxyproline were evaluated by immunohistochemistry, in situ detection of apoptosis, electron microscopy, immunofluorescence, and histomorphometry. Electron microscopy confirmed the presence of increased alveolar epithelial cells type 1 (AEC1) in apoptosis. Immunostaining showed increased nuclear expression of telomerase in AEC type 2 (AEC2) between normal and chronic scarring areas of usual interstitial pneumonia (UIP). Control lungs and normal areas from UIP lungs showed weak green birefringence of type I and III collagens in the alveolar wall and type V collagen in the basement membrane of alveolar capillaries. The increase in collagen V was greater than collagens I and III in scarring areas of UIP. A significant direct association was found between collagen V and AEC2 apoptosis. We concluded that telomerase, collagen V fiber density, and apoptosis evaluation in experimental UIP offers the potential to control reepithelization of alveolar septa and fibroblast proliferation. Strategies aimed at preventing high rates of collagen V synthesis, or local responses to high rates of cell apoptosis, may have a significant impact in pulmonary fibrosis.
Subject(s)
Apoptosis/physiology , Collagen Type V/biosynthesis , Idiopathic Pulmonary Fibrosis/pathology , Pulmonary Fibrosis/pathology , Telomerase/metabolism , Animals , Butylated Hydroxytoluene , Cell Proliferation , Collagen Type I/analysis , Collagen Type II/analysis , Collagen Type V/analysis , Disease Models, Animal , Epithelial Cells/metabolism , Epithelial Cells/pathology , Fibroblasts/metabolism , Fibroblasts/pathology , Fluorescent Antibody Technique , Hydroxyproline/analysis , Immunohistochemistry , In Situ Nick-End Labeling , Male , Mice, Inbred BALB C , Microscopy, Electron , Pulmonary Alveoli/pathology , Pulmonary Alveoli/ultrastructure , Staining and Labeling , Telomerase/isolation & purificationABSTRACT
Decidualization in the mouse consists of an extensive remodeling of the endometrial extracellular matrix, resulting in a reduction of the extracellular spaces, an increase in the diameter of collagen fibrils, and changes in the relative ratio of different types of glycosaminoglycans. To assess the dynamic changes of the endometrial extracellular matrix during decidualization, collagen was analyzed biochemically and immunochemically in the endometrium of nulliparous and day 5 to day 8 pregnant mice. The amount of collagen per gram dry weight was higher in the endometrium of implantation sites than in interimplantation sites. Collagen types I, III, and V were the main components of the endometrium of nulliparous and pregnant animals. The amount of collagen type V was higher in the endometrium of pregnant animals than in nulliparous ones. A relative unusual homotrimeric form of collagen type V, probably formed by [alpha1(V)](3), was detected in pregnant endometrium by gel eletrophoresis and immunoblotting.
