Activation of alveolar macrophages in lung injury associated with experimental acute pancreatitis is mediated by the liver.
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OBJECTIVE: To evaluate (1) whether alveolar macrophages are activated as a consequence of acute pancreatitis (AP), (2) the implication of inflammatory factors released by these macrophages in the process of neutrophil migration into the lungs observed in lung injury induced by AP, and (3) the role of the liver in the activation of alveolar macrophages. SUMMARY BACKGROUND DATA: Acute lung injury is the extrapancreatic complication most frequently associated with death and complications in severe AP. Neutrophil infiltration into the lungs seems to be related to the release of systemic and local mediators. The liver and alveolar macrophages are sources of mediators that have been suggested to participate in the lung damage associated with AP. METHODS: Pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. The inflammatory process in the lung and the activation of alveolar macrophages were investigated in animals with and without portocaval shunting 3 hours after AP induction. Alveolar macrophages were obtained by bronchoalveolar lavage. The generation of nitric oxide, leukotriene B4, tumor necrosis factor-alpha, and MIP-2 by alveolar macrophages and the chemotactic activity of supernatants of cultured macrophages were evaluated. RESULTS: Pancreatitis was associated with increased infiltration of neutrophils into the lungs 3 hours after induction. This effect was prevented by the portocaval shunt. Alveolar macrophages obtained after induction of pancreatitis generated increased levels of nitric oxide, tumor necrosis factor-alpha, and MIP-2, but not leukotriene B4. In addition, supernatants of these macrophages exhibited a chemotactic activity for neutrophils when instilled into the lungs of unmanipulated animals. All these effects were abolished when portocaval shunting was carried out before induction of pancreatitis. CONCLUSION: Lung damage induced by experimental AP is associated with alveolar macrophage activation. The liver mediates the alveolar macrophage activation in this experimental model. (+info)
The Pseudomonas aeruginosa secretory product pyocyanin inactivates alpha1 protease inhibitor: implications for the pathogenesis of cystic fibrosis lung disease.
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Alpha1 Protease inhibitor (alpha1PI) modulates serine protease activity in the lung. Reactive oxygen species inactivate alpha1PI, and this process has been implicated in the pathogenesis of a variety of forms of lung injury. An imbalance of protease-antiprotease activity is also detected in the airways of patients with cystic fibrosis-associated lung disease who are infected with Pseudomonas aeruginosa. P. aeruginosa secretes pyocyanin, which, through its ability to redox cycle, induces cells to generate reactive oxygen species. We tested the hypothesis that redox cycling of pyocyanin could lead to inactivation of alpha1PI. When alpha1PI was exposed to NADH and pyocyanin, a combination that results in superoxide production, alpha1PI lost its ability to form an inhibitory complex with both porcine pancreatic elastase (PPE) and trypsin. Similarly, addition of pyocyanin to cultures of human airway epithelial cells to which alpha1PI was also added resulted in a loss of the ability of alpha1PI to form a complex with PPE or trypsin. Neither superoxide dismutase, catalase, nor dimethylthiourea nor depletion of the media of O2 to prevent formation of reactive oxygen species blocked pyocyanin-mediated inactivation of alpha1PI. These data raise the possibility that a direct interaction between reduced pyocyanin and alpha1PI is involved in the process. Consistent with this possibility, pretreatment of alpha1PI with the reducing agent beta-mercaptoethanol also inhibited binding of trypsin to alpha1PI. These data suggest that pyocyanin could contribute to lung injury in the P. aeruginosa-infected airway of cystic fibrosis patients by decreasing the ability of alpha1PI to control the local activity of serine proteases. (+info)
C5a receptor and interleukin-6 are expressed in tissue macrophages and stimulated keratinocytes but not in pulmonary and intestinal epithelial cells.
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The anaphylatoxin derived from the fifth component of the human complement system (C5a) mediates its effects by binding to a single high-affinity receptor (C5aR/CD88), the expression of which has been traditionally thought to be restricted to granulocytes, monocytes, macrophages (Mphi), and cell lines of myeloid origin. Recent immunohistochemical data suggested that human bronchial and alveolar cells express C5aR as well. To reexamine the tissue distribution of human C5aR expression, transcription of the C5aR gene was investigated in normal and pathologically affected human lung (bronchopneumonia, tuberculosis), large intestine (acute appendicitis, Crohn's disease), and skin (pyogenic granuloma, lichen planus) using in situ hybridization. In contrast to previous evidence, C5aR mRNA could not be detected in pulmonary or intestinal epithelial cells, whereas keratinocytes in inflamed but not in normal skin revealed detectable levels of C5aR transcripts. Additionally, it could be documented that only migrating Mphi express C5aR mRNA, whereas sessile Mphi in normal tissues and epithelioid/multinucleated Mphi found in granulomatous lesions do not. Because C5a has been demonstrated to upregulate the expression of interleukin (IL)-6 in human monocytes, we also studied IL-6 gene transcription in parallel to the C5aR. IL-6 mRNA was detectable in many tissue Mphi. Surprisingly, a tight co-expression of C5aR and IL-6 mRNA was observed in keratinocytes from lesions of pyogenic granuloma and lichen planus. These results point to an as yet unknown role for C5a in the pathogenesis of skin disorders beyond its well-defined function as a chemoattractant and activator of leukocytes. (+info)
Mechanisms and mediators in coal dust induced toxicity: a review.
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Chronic inhalation of coal dust can cause several lung disorders, including simple coal workers pneumoconiosis (CWP), progressive massive fibrosis (PMF), chronic bronchitis, lung function loss, and emphysema. This review focuses on the cellular actions and interactions of key inflammatory cells and target cells in coal dust toxicity and related lung disorders, i.e. macrophages and neutrophils, epithelial cells, and fibroblasts. Factors released from or affecting these cells are outlined in separate sections, i.e. (1) reactive oxygen species (ROS) and related antioxidant protection mechanisms, and (2) cytokines, growth factors and related proteins. Furthermore, (3) components of the extracellular matrix (ECM), including the modifying role of ROS, cytokines, proteases and antiproteases are discussed in relation to tissue damage and remodelling in the respiratory tract. It is recognised that inhaled coal dust particles are important non-cellular and cellular sources of ROS in the lung, and may be significantly involved in the damage of lung target cells as well as important macromolecules including alpha-1-antitrypsin and DNA. In vitro and in vivo studies with coal dusts showed the up-regulation of important leukocyte recruiting factors, e.g. Leukotriene-B4 (LTB4), Platelet Derived Growth Factor (PDGF), Monocyte Chemotactic Protein-1 (MCP-1), and Tumor Necrosis Factor-alpha (TNF alpha), as well as the neutrophil adhesion factor Intercellular Adhesion Molecule-1 (ICAM-1). Coal dust particles are also known to stimulate the (macrophage) production of various factors with potential capacity to modulate lung cells and/or extracellular matrix, including O2-., H2O2, and NO, fibroblast chemoattractants (e.g. Transforming Growth Factor-beta (TGF beta), PDGF, and fibronectin) and a number of factors that have been shown to stimulate and/or inhibit fibroblast growth or collagen production such as (TNF alpha, TGF beta, PDGF, Insulin Like Growth Factor, and Prostaglandin-E2). Further studies are needed to clarify the in vivo kinetics and relative impact of these factors. (+info)
Computed radiography dual energy subtraction: performance evaluation when detecting low-contrast lung nodules in an anthropomorphic phantom.
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A dedicated chest computed radiography (CR) system has an option of energy subtraction (ES) acquisition. Two imaging plates, rather than one, are separated by a copper filter to give a high-energy and low-energy image. This study compares the diagnostic accuracy of conventional computed radiography to that of ES obtained with two radiographic techniques. One soft tissue only image was obtained at the conventional CR technique (s = 254) and the second was obtained at twice the radiation exposure (s = 131) to reduce noise. An anthropomorphic phantom with superimposed low-contrast lung nodules was imaged 53 times for each radiographic technique. Fifteen images had no nodules; 38 images had a total of 90 nodules placed on the phantom. Three chest radiologists read the three sets of images in a receiver operating characteristic (ROC) study. Significant differences in Az were only found between (1) the higher exposure energy subtracted images and the conventional dose energy subtracted images (P = .095, 90% confidence), and (2) the conventional CR and the energy subtracted image obtained at the same technique (P = .024, 98% confidence). As a result of this study, energy subtracted images cannot be substituted for conventional CR images when detecting low-contrast nodules, even when twice the exposure is used to obtain them. (+info)
Computerized analysis of abnormal asymmetry in digital chest radiographs: evaluation of potential utility.
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The purpose of this study was to develop and test a computerized method for the fully automated analysis of abnormal asymmetry in digital posteroanterior (PA) chest radiographs. An automated lung segmentation method was used to identify the aerated lung regions in 600 chest radiographs. Minimal a priori lung morphology information was required for this gray-level thresholding-based segmentation. Consequently, segmentation was applicable to grossly abnormal cases. The relative areas of segmented right and left lung regions in each image were compared with the corresponding area distributions of normal images to determine the presence of abnormal asymmetry. Computerized diagnoses were compared with image ratings assigned by a radiologist. The ability of the automated method to distinguish normal from asymmetrically abnormal cases was evaluated by using receiver operating characteristic (ROC) analysis, which yielded an area under the ROC curve of 0.84. This automated method demonstrated promising performance in its ability to detect abnormal asymmetry in PA chest images. We believe this method could play a role in a picture archiving and communications (PACS) environment to immediately identify abnormal cases and to function as one component of a multifaceted computer-aided diagnostic scheme. (+info)
Lymphomatoid granulomatosis following autologous stem cell transplantation.
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Lymphomatoid granulomatosis (LYG) is a rare angio-destructive lymphoproliferative disorder (LPD) of uncertain etiology, with prominent pulmonary involvement. Recent studies indicate that LYG is an Epstein-Barr virus (EBV)-associated B cell LPD with large numbers of background reactive T lymphocytes (T cell-rich B cell lymphoma). Although the disease frequently, but not exclusively, occurs in various immunodeficiency states, it has not been reported in association with the transient immunosuppression following autologous bone marrow/peripheral stem cell transplantation (ABM/PSCT). We describe a patient who developed lymphomatoid granulomatosis of the lung approximately 2 weeks after high-dose chemotherapy and autologous peripheral stem cell transplantation for multiple myeloma. Although molecular studies showed no evidence of EBV genome in the biopsy material, the serologic profile with high IgM titers was suggestive of primary EBV infection. Complete radiologic remission occurred following reconstitution of the patient's immune response after a 2-week course of ganciclovir treatment. Despite the apparently low frequency of LPD (both LYG and EBV-associated post-transplant lymphoma) in the ABMT setting, we believe that it should be considered in the differential diagnosis of patients whose clinical course following ABMT is complicated by fevers, in the absence of an identifiable infectious process. (+info)
Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats.
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Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes. (+info)