Literatura científica selecionada sobre o tema "Lung dividing cells"

ABSTRACT Jaagsiekte sheep retrovirus (JSRV) infects lung epithelial cells in sheep, and oncoretroviral vectors bearing JSRV Env can mediate transduction of human cells, suggesting that such vectors might be useful for lung-directed gene therapy. Here we show that JSRV Env can also efficiently pseudotype a human immunodeficiency virus type 1-based lentiviral vector, a more suitable vector for transduction of slowly dividing lung epithelial cells. We created several chimeric Env proteins that, unlike the parental Env, do not transform rodent fibroblasts but are still capable of pseudotyping lentiviral and oncoretroviral vectors.

An overview of the epithelial and interstitial composition of rat respiratory airways shows complexity and variability. Airway epithelium varies in 1) different airway levels; 2) the types and ultrastructure of cells present; and 3) the abundance, type, and composition of stored secretory product. Unbiased sampling of airways is done using airway microdissection with a specific binary numbering system for airway generation. Vertical sections of selected airways are used to sample epithelium and interstitium. We determine the ratios of the volume of epithelial or interstitial cells to the total epithelial or interstitial volume (Vv). The surface of the epithelial basal lamina to the total epithelial or interstitial volume (Sv) is determined using point and intersection counting with a cycloid grid. Using the selector method on serial plastic sections, we determine the number of epithelial or interstitial cells per volume (Nv) of total epithelium or interstitium. We calculate the number of epithelial or interstitial cells per surface of epithelial basal lamina (Ns) by dividing Nv by Sv where the volumes are the same compartment. We calculate average cell volumes (v̄) for specific epithelial and interstitial cells by dividing the absolute nuclear volume by the ratio of the nucleus to cell volume (Vv). By multiplying the average cell volume (v̄) by the ratio of organellar volume to cell volume (Vv), we calculate the average organellar volume per cell. These unbiased stereological approaches are critical in a quantitative evaluation of toxicological injury of rat tracheobronchial airways.

Cellular remodeling during angiogenesis in the lung is poorly described. Furthermore, it is the systemic vasculature of the lung and surrounding the lung that is proangiogenic when the pulmonary circulation becomes impaired. In a mouse model of chronic pulmonary thromboembolism, after left pulmonary artery ligation (LPAL), the intercostal vasculature, in proximity to the ischemic lung, proliferates and invades the lung ( 12 ). In the present study, we performed a detailed investigation of the kinetics of remodeling using histological sections of the left lung of C57Bl/6J mice after LPAL (4 h to 20 days) or after sham surgery. New vessels were seen within the thickened visceral pleura 4 days after LPAL predominantly in the upper portion of the left lung. Connections between new vessels within the pleura and pulmonary capillaries were clearly discerned by 7 days after LPAL. The visceral pleura and the lung parenchyma showed intense tissue remodeling, as evidenced by markedly elevated levels of both proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells. Rapidly dividing cells were predominantly macrophages and type II pneumocytes. The increased apoptotic activity was further quantified by caspase-3 activity, which showed a sixfold increase relative to naive lungs, by 24 h after LPAL. Because sham surgeries had little effect on measured parameters, we conclude that both thoracic wound healing and pulmonary ischemia are required for systemic neovascularization.

To examine the role of simian virus 40 (SV40) large T and small t antigens in tumorigenesis in animals, we generated transgenic mice which expressed either both the SV40 large T and small t antigens or the SV40 large T antigen alone under the control of the mouse mammary tumor virus long terminal repeat. The mouse mammary tumor virus long terminal repeat directs the expression of transgenes in ductal epithelial cells of several organs, including the mammary gland, lung, and kidney, and in lymphoid cells. The mice which expressed both the T and t tumor antigens developed lung and kidney adenocarcinomas, while those which expressed large T alone did not. Both types of mice developed malignant lymphomas with similar frequencies and latency periods. Our results show that the SV40 small t antigen cooperates with the large T antigen in inducing tumors in slowly dividing epithelial cells in the lung and kidney.

To examine the role of simian virus 40 (SV40) large T and small t antigens in tumorigenesis in animals, we generated transgenic mice which expressed either both the SV40 large T and small t antigens or the SV40 large T antigen alone under the control of the mouse mammary tumor virus long terminal repeat. The mouse mammary tumor virus long terminal repeat directs the expression of transgenes in ductal epithelial cells of several organs, including the mammary gland, lung, and kidney, and in lymphoid cells. The mice which expressed both the T and t tumor antigens developed lung and kidney adenocarcinomas, while those which expressed large T alone did not. Both types of mice developed malignant lymphomas with similar frequencies and latency periods. Our results show that the SV40 small t antigen cooperates with the large T antigen in inducing tumors in slowly dividing epithelial cells in the lung and kidney.

The effects of 17 xenobiotics on rat hepatocytes and V79 cells were evaluated under identical exposure conditions (confluent monolayer for 24 hours) and endpoint measurement (MTT reduction). The data indicated that the majority of metabolically-activated rat hepatotoxins could be identified by greater cytotoxicity to rat hepatocytes relative to V79 cells, but that direct-acting hepatotoxins (galactosamine and ethionine) and a group of eight compounds likely to act through interference of basal functions in non-dividing and dividing cells produced similar toxicity in each cell type. It is possible that the greater water-solubility of the direct-acting hepatotoxins relative to the indirect-acting hepatotoxins may contribute to the lack of effect seen with the former group under the conditions of the assay (top concentration of 1mM).

The bloodstream is an important route of dissemination of invading pathogens. Most of the small bloodborne pathogens, like bacteria or viruses, are filtered by the spleen or liver sinusoids and presented to the immune system by dendritic cells (DCs) that probe these filters for the presence of foreign antigen (Ag). However, larger pathogens, like helminths or infectious emboli, that exceed 20 µm are mostly trapped in the vasculature of the lung. To determine if Ag trapped here can be presented to cells of the immune system, we used a model of venous embolism of large particulate Ag (in the form of ovalbumin [OVA]-coated Sepharose beads) in the lung vascular bed. We found that large Ags were presented and cross-presented to CD4 and CD8 T cells in the mediastinal lymph nodes (LNs) but not in the spleen or liver-draining LNs. Dividing T cells returned to the lungs, and a short-lived infiltrate consisting of T cells and DCs formed around trapped Ag. This infiltrate was increased when the Toll-like receptor 4 was stimulated and full DC maturation was induced by CD40 triggering. Under these conditions, OVA-specific cytotoxic T lymphocyte responses, as well as humoral immunity, were induced. The T cell response to embolic Ag was severely reduced in mice depleted of CD11chi cells or Ly6C/G+ cells but restored upon adoptive transfer of Ly6Chi monocytes. We conclude that the lung vascular filter represents a largely unexplored site of immune induction that traps large bloodborne Ags for presentation by monocyte-derived DCs.

Continuous exposure to low concentrations of ozone has previously been associated with proliferation of lung alveolar type II epithelial cells. In this study, 14C incorporation into tissue lipids was determined in isolated rat lungs by perfusion with [U-14C]glucose, at a time of maximal hyperplasia brought about by 3 days continuous exposure to 0.6 ppm ozone. Ozone exposed lungs exhibited increased rates of glycolytic energy production, indicated by an 89% increase in 3H2O generation on perfusion with [5-3H]glucose, from a control value of 17.5 +/- 2.1 mumol X h-1 X g-1 X dry wt-1 (+/- SE, n = 4). Ozone exposure resulted in enhanced 14C incorporations into glyceride-glycerol and fatty acid moieties of lung lipids of 95 and 180%, respectively, with a greater proportion of label being recovered in shorter chain fatty acids. Although increased labeling was observed in both neutral and phospholipids, the pattern of 14C recovery suggested a relative increased glucose carbon incorporation into lung free fatty acids, phosphatidic acid, and such membrane associated lipids as phosphatidylinositol and those containing sphingosine. These results are consistent with the needs of a dividing cell population for enhanced energy production and synthesis of new lipids.

The alveolar epithelium is a dynamic tissue, consisting of cells of types I and II, covering more than 99 % of the lung inner surface and actively responding to various endogenous and exogenous stimuli. The technology of alveolocyte isolation is presented, which consists in mechanical disaggregation of tissue with subsequent processing of the resulting explants with 0.25 % trypsin solution in combination with filtration of the cell suspension through pores with a diameter of 100 µm and 50 µm. In two-dimensional static culture viable actively dividing rounded cells and large alveolar epithelial cells with cuboid or polygonal morphology, producing surfactant proteins, were visualized.

Macrophage precursors and their progeny have been identified in early rat embryos with the use of a peroxidase-coupled marker, isolectin B4 of Griffonia simplicifolia (GSA I-B4). The macrophage lineage can be traced back to actively dividing GSA-positive angular cells present in the mesenchyme of late neurulas. These increase in number and establish residence successively in rudiments of the central nervous system, liver, and lungs. In organ-cultured fetal lungs they transform directly into a self-replicating population of macrophages responsive to colony-stimulating factors. The angular cell therefore can be seen as the source of lung macrophages during prenatal life. The extent to which this manner of production continues in postnatal life is unclear, but it appears that central hematopoietic tissues (bone marrow, spleen) may generate macrophages by a direct pathway from early-committed progenitors as well as indirectly through a series of intermediate stem cells. Considering the wealth of new information available from diverse studies in specialized culture environments and to a lesser extent from studies in vivo, it is time to integrate these findings into a more comprehensive theory of macrophage origin and fate than we have at present.

La radiothérapie est une option thérapeutique essentielle pour environ 50 % des patients atteints de cancer, mais elle peut endommager les tissus sains environnants, entraînant des toxicités aiguës ou chroniques. Dans le poumon, les dommages induits par les radiations se manifestent par une pneumonie, qui peut évoluer vers une fibrose pulmonaire. La radiothérapie FLASH, une nouvelle modalité de traitement à ultra-hauts débits de dose, a montré qu’elle pouvait épargner les tissus sains tout en maintenant son efficacité antitumorale, effet qui a été observé dans plusieurs organes. Cependant, des défis subsistent avant une transition clinique réussie, notamment la nécessité de définir les paramètres d’irradiation optimaux et de mieux comprendre les mécanismes sous-jacents du FLASH. Dans ces travaux, nous avons développé d’une part un modèle ex vivo de coupes organotypiques de poumons pour étudier l’effet d’épargne du FLASH dans la phase aigüe de réponse aux dommages radio-induits. Ce modèle nous a permis de démontrer que l’irradiation FLASH épargne les cellules en cycle dans le poumon par rapport à la radiothérapie conventionnelle. A l’aide de ce modèle, nous avons également étudié les paramètres d’irradiation optimaux pour déclencher l’effet de protection, en montrant que le débit de dose et la dose par pulse sont des facteurs cruciaux. Ensuite, nous avons apporté une première preuve clinique d’un effet protecteur de la radiothérapie FLASH sur le tissu sain humain en développant un modèle de coupes organotypiques dérivés de résection pulmonaire. Enfin, à l’aide d’analyse en cellule unique, nous avons identifié de potentiels mécanismes sous-jacents, notamment une épargne du métabolisme lipidique dans les cellules AT2, des fonctions mitochondriales dans les cellules endothéliales et finalement de premières données concernant des voies d’activation différentielle de la régénération alvéolaire dans les cellules qui cyclent via la voie MIF/Cd74. Bien que de nouvelles validations restent en cours, l’ensemble de ces travaux supporte la transition clinique du FLASH et aide à une meilleure compréhension de ces mécanismes sous-jacents survenant dans la phase de toxicité aigüe dans le poumon
Radiotherapy is a crucial therapeutic option for approximately 50% of cancer patients, but it can damage surrounding healthy tissues, leading to acute or chronic toxicities. In the lungs, radiation-induced damage manifests as pneumonitis, which can progress to pulmonary fibrosis. FLASH radiotherapy, a new treatment modality that delivers ultra-high dose rates, has been shown to spare healthy tissues while maintaining anti- tumor efficacy, an effect observed in several organs. However, challenges remain before successful clinical implementation, including the need to define optimal irradiation parameters and better understand the underlying mechanisms of FLASH. In this work, we developed an ex vivo PCLS model to study the sparing effect in the acute phase of pulmonary radio- induced injury. Using this model, we demonstrated that FLASH irradiation spares cycling cells in the lung compared to conventional radiotherapy. We also explored the optimal irradiation parameters to trigger the protective effect, showing that dose rate and pulse dose are crucial factors. Furthermore, we provided the first clinical evidence of a FLASH radiotherapy protective effect on healthy human tissue by developing organotypic slices derived from lung resections. Finally, using scRNAseq analysis, we identified potential underlying mechanisms, including sparing effects on lipid metabolism in AT2 cells, mitochondrial function preservation in endothelial cells, and preliminary data on different activation pathways for alveolar regeneration in cycling cells via the MIF/Cd74 pathway. Although further validations are underway, these findings support the clinical transition of FLASH and contribute to a better understanding of the underlying mechanisms occurring at the acute phase of pulmonary radio-induced injury

The lungs can be injured by radiation used in cancer treatment, with the rapidly dividing endothelial cells and type II pneumocytes most affected. Immediate injury is followed by an inflammatory response and at a later stage by fibrosis. Chest radiography reveals asymptomatic changes in about 50% of patients after radiotherapy. ...

The lungs can be injured by radiation used in the treatment of cancer, with the rapidly dividing endothelial cells and type II pneumocytes most affected. Immediate injury is followed by an inflammatory response and at a later stage by fibrosis. Chest radiography detects asymptomatic changes in about 50% of patients after radiotherapy. Acute radiation pneumonitis presents with cough, breathlessness, and fever about 2 months after exposure; corticosteroids are usually effective in relieving symptoms but do not prevent the subsequent development of fibrosis. Fibrosis typically develops about 6 months later, may progress for 6–24 months, but has usually stabilized by 2 years. Prevention depends on refining techniques for giving radiotherapy.

Evaluation of various proteolytic enzymes efficiency for disaggregation of lung tissue is carried out and an optimized method for alveolar epithelial cells isolation is presented. This method includes mechanical disaggregation of tissue followed by processing of explanations with 0.25% trypsin solution in combination with filtration of the cell suspension through pores with a diameter of 100 gm and 50 gm. The obtained cell cultures were characterized by high viability (more than 91%) and morphological heterogeneity. Along with actively dividing rounded cells, differentiated alveolar epithelial cells with cuboid or polygonal morphology, characterized by high secretory activity, were visualized.