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Query: UMLS:C0034069 (pulmonary fibrosis)
 7,050 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytosolic phospholipase A2alpha (cPLA2alpha) preferentially hydrolyzes phospholipids containing arachidonic acid and plays a key role in the biosynthesis of eicosanoids. This review discusses the essential features of cPLA2alpha regulation and addresses new insights into the functional properties of this enzyme. Full activation of the enzyme requires Ca2+ binding to an N-terminal C2 domain and phosphorylation on serine residues. Ca2+ binding induces translocation of cPLA2alpha from the cytosol to the perinuclear membranes. Serine phosphorylation is mediated by mitogen-activated protein kinases (MAPKs), Ca2+/calmodulin-dependent protein kinase II, and MAPK-interacting kinase Mnk1. Interaction with proteins and lipids, which include vimentin, annexins, NADPH oxidase, phosphatidylcholine, phosphatidylinositol 4,5-bisphosphate (PIP2), and ceramide-1-phosphate, can also modulate the activity of cPLA2alpha. Recent evidence has established the physiological and pathological roles of cPLA2alpha using cPLA2alpha knockout mice. This enzyme has been implicated in fertility, striated muscle growth, renal concentration, postischemic brain injury, arthritis, inflammatory bone resorption, intestinal polyposis, pulmonary fibrosis, acute respiratory distress syndrome, and autoimmune encephalomyelitis. Now novel three paralogs, cPLA2beta, cPLA2gamma, and cPLA2delta, have been identified in humans. cPLA2gamma is distinct from others in that it is farnesylated and lacks the C2 domain. Biological roles for these new enzymes have not yet been defined.
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PMID:Regulatory mechanism and physiological role of cytosolic phospholipase A2. 1530 15

The mode of cell death termed apoptosis, sometimes referred to as programmed cell death, is as critical a determinant of cell population size as is cell proliferation. Although best characterized in cells of the immune system, apoptosis is now known to be a key factor in the maintenance of normal cell turnover within structural cells in the parenchyma of virtually every organ. Recent interest in apoptosis in the lung has sparked a surge of investigations designed to determine the roles of apoptosis in lung development, injury, and remodeling. Of particular recent interest are the roles of apoptosis in disease pathogenesis and resolution, in which the concept of apoptosis as a "programmed" cell death, i.e., genetically determined, is often more accurately viewed as "inappropriate cell suicide" with regard to its extent and/or timing. Data accumulating over the past decade have made clear the complexity of the control of lung cell apoptosis; concepts of the regulation of apoptosis originally determined in classical cell culture models are often, but not always, applicable to structural cells. For this reason, each of the many cell types of the lung must be studied as a potentially new subject with its own idiosyncrasies yet to be discovered. In light of the large volume of literature now available, this article focuses on the roles of apoptosis in three pathophysiological contexts: acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis. Each section presents key data describing the evidence for apoptosis in the lung, its possible relevance to disease pathogenesis, and proposed mechanisms that might suggest potential avenues for therapeutic intervention.
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PMID:Apoptosis in lung injury and remodeling. 1535 56

Tracheoesophageal fistula is an uncommon complication usually associated with chronic usage of ventilator and pressure necrosis of the tracheoesophageal wall. A 56-year-old female patient with severe acute respiratory syndrome (SARS) with tracheoesophageal fistula is reported. She was intubated for ventilatory support 3 days after admission because of progressive respiratory distress. Methylprednisolone pulse therapy followed by a maintenance dosage was given due to persistence of bilateral pulmonary fibrosis. Thirty three days after admission, she underwent tracheostomy because of difficulty in weaning from the ventilator. Ten days after tracheostomy, she developed tracheoesophageal fistula, which was confirmed by bronchoscopy and panendoscopy. Tracheal resection and primary repair for the esophageal defect was performed via a cervical incision combined with partial sternotomy. She was weaned from the ventilator soon after the surgery and discharged 34 days after the operation. In SARS patients with persistent pulmonary fibrosis and under prolonged corticosteroid treatment, special care should be given to avoid intubation-related tracheal injury during the period of ventilatory support. The tracheoesophageal fistula, once developed, can be repaired in a single stage after improvement of the nutritional status.
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PMID:Surgical treatment of tracheoesophageal fistula in a patient with severe acute respiratory syndrome complicated with extensive pulmonary fibrosis. 1562 43

It has been speculated that the destruction of lung tissue, associated with several acute and chronic diseases, is in part mediated through apoptosis or programmed cell death. Thus, it has been shown that both increased endothelial/epithelial cell apoptosis and decreased cell death of inflammatory cells are associated with acute lung injury/acute respiratory distress syndrome, chronic obstructive pulmonary disease, asthma and pulmonary fibrosis. In the light of these observations, it might be possible to use apoptosis modulation as a novel therapeutic approach to the treatment of lung disease.
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PMID:Apoptosis as a therapeutic target for the treatment of lung disease. 1590 8

Acute interstitial pneumonitis (AIP) is a fulminant disease culminating in acute respiratory failure and often death. Originally described in 1935 by the pathologists Hamman and Rich, this rare syndrome is characterized by rapidly progressive pulmonary fibrosis, leading to frequent confusion with idiopathic pulmonary fibrosis. In fact, the eponym Hamman-Rich syndrome became synonymous with idiopathic pulmonary fibrosis despite clear differences in clinical presentation, radiography, pathology, and survival. In 1986, Katzenstein described eight patients with acute respiratory failure of unknown etiology. On biopsy, organizing diffuse alveolar damage was present in all specimens. Given the idiopathic nature of the disease, Katzenstein coined the phrase acute interstitial pneumonitis to distinguish it from the fibroproliferative stage of the acute respiratory distress syndrome (ARDS), which has an identical pathology. Olson et al retrospectively examined Hamman and Rich's original cases, compared them to contemporary cases of AIP, and found the two identical. Since then, little progress into understanding this disease has been made. Many questions still linger regarding the epidemiology, pathogenesis, and outcome. We recently published our experience with AIP providing new information regarding natural history. This review summarizes the current literature on AIP emphasizing diagnostic criteria, pathogenesis, and natural history.
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PMID:Acute interstitial pneumonitis: current understanding regarding diagnosis, pathogenesis, and natural history. 1608 88

Adenosine, a signaling nucleoside, exhibits tissue-protective and tissue-destructive effects. Adenosine levels in tissues are controlled in part by the enzyme adenosine deaminase (ADA). ADA-deficient mice accumulate adenosine levels in multiple tissues, including the lung, where adenosine contributes to the development of pulmonary inflammation and chronic airway remodeling. The present study describes the development of pulmonary fibrosis in mice that have been genetically engineered to possess partial ADA enzyme activity and, thus, accumulate adenosine over a prolonged period of time. These partially ADA-deficient mice live for up to 5 mo and die from apparent respiratory distress. Detailed investigations of the lung histopathology of partially ADA-deficient mice revealed progressive pulmonary fibrosis marked by an increase in the number of pulmonary myofibroblasts and an increase in collagen deposition. In addition, in regions of the distal airways that did not exhibit fibrosis, an increase in the number of large foamy macrophages and a substantial enlargement of the alveolar air spaces suggest emphysemic changes. Furthermore, important proinflammatory and profibrotic signaling pathways, including IL-13 and transforming growth factor-beta1, were activated. Increases in tissue fibrosis were also seen in the liver and kidneys of these mice. These changes occurred in association with pronounced elevations of lung adenosine concentrations and alterations in lung adenosine receptor levels, supporting the hypothesis that elevation of endogenous adenosine is a proinflammatory and profibrotic signal in this model.
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PMID:Partially adenosine deaminase-deficient mice develop pulmonary fibrosis in association with adenosine elevations. 1625

Apoptosis is important in developmental biology and in remodeling of tissues during repair. Apoptosis also plays important roles in the progression of many diseases. The cellular and molecular mechanisms of apoptosis, in general, have been extensively demonstrated. However, the causes and the roles of apoptosis of various cell types in the lung are not well understood. We have determined that adenosine/homocysteine causes lung vascular endothelial cell apoptosis by inhibition of carboxyl methylation of the small GTPase, Ras, through inhibition of isoprenylcysteine carboxyl methyltransferase(ICMT) activity, leading to inactivation of Ras and the subsequent disruption of focal adhesion complexes, resulting in cell-extracellular matrix detachment and anoikis. Apoptosis can either ameliorate or exacerbate lung injury, depending upon the cell type. Although apoptosis of polymorphonuclear leukocytes in the lung prevents inflammation and the development of acute respiratory distress syndrome during acute lung injury, Fas/FasL-mediated alveolar epithelial cell apoptosis promotes acute lung injury and pulmonary fibrosis. Lung epithelial and endothelial cell apoptosis also contributes to the development of emphysema. This article focuses on elucidating the mechanisms of adenosine/homocysteine-induced endothelial cell apoptosis. We also review the current understanding of the role of lung cell apoptosis in acute lung injury, pulmonary fibrosis and emphysema.
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PMID:Apoptosis and lung injury. 1645 28

Pulmonary surfactant, a complex of lipids and proteins, functions to keep alveoli from collapsing at expiration. Surfactant proteins A (SP-A) and D (SP-D) belong to the collectin family and play pivotal roles in the innate immunity of the lung. Pulmonary collectins directly bind with broad specificities to a variety of microorganism and possess anti-microbial effects. These proteins also exhibit both inflammatory and anti-inflammatory functions, which occur through interactions with pattern recognition receptors including Toll-like receptor and CD14, signal inhibitory regulatory protein alpha and a receptor complex of calreticulin and CD91. The collectins enhance phagocytosis of microbes by macrophages through opsonic and/or non-opsonic activities. The proteins stimulate cell surface expression of phagocytic receptors including scavenger receptor A and mannose receptor. Since the expression of SP-A and SP-D is abundant and restricted within the lung, the proteins are now clinically used as biomarkers for lung diseases. The levels of SP-A and SP-D in bronchoalveolar lavage fluids, amniotic fluids, tracheal aspirates and pleural effusions reflect alterations in alveolar compartments and epithelium, and lung maturity. The determination of SP-A and SP-D in sera is a non-invasive and useful tool for understanding some pathological changes of the lung in the diseases, including pulmonary fibrosis, collagen vascular diseases complicated with interstitial lung disease, pulmonary alveolar proteinosis, acute respiratory distress syndrome and radiation pneumonitis.
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PMID:Pulmonary surfactant proteins A and D: innate immune functions and biomarkers for lung diseases. 1647 50

The renin-angiotensin system (RAS) plays a key role in maintaining blood pressure homeostasis, as well as fluid and salt balance. Angiotensin II, a key effector peptide of the system, causes vasoconstriction and exerts multiple biological functions. Angiotensin-converting enzyme (ACE) plays a central role in generating angiotensin II from angiotensin I, and capillary blood vessels in the lung are one of the major sites of ACE expression and angiotensin II production in the human body. The RAS has been implicated in the pathogenesis of pulmonary hypertension and pulmonary fibrosis, both commonly seen in chronic lung diseases such as chronic obstructive lung disease. Recent studies indicate that the RAS also plays a critical role in acute lung diseases, especially acute respiratory distress syndrome (ARDS). ACE2, a close homologue of ACE, functions as a negative regulator of the angiotensin system and was identified as a key receptor for SARS (severe acute respiratory syndrome) coronavirus infections. In the lung, ACE2 protects against acute lung injury in several animal models of ARDS. Thus, the RAS appears to play a critical role in the pathogenesis of acute lung injury. Indeed, increasing ACE2 activity might be a novel approach for the treatment of acute lung failure in several diseases.
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PMID:Angiotensin-converting enzyme 2 in lung diseases. 1658 Dec 95

Adenovirus pneumonia is uncommon but its severe infection has a mortality as high as 10%, and survivors may have residual airway damages, manifested by bronchiectasis, bronchiolitis obliterans, or pulmonary fibrosis. We report a case of adenovirus pneumonia demonstrating fatal respiratory distress. Adenovirus was isolated from pharyngeal specimens using cell culture and typed as serotype 3 by a combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. The patient characteristically showed hypercytokinemia, characterized by increased levels of lactate dehydrogenase, ferritin, and several cytokines including interferon-gamma and interleukin-6. We treated the patient with pulse methylprednisolne therapy (25 mg/kg/day, for 3 days), resulting in the rapid amelioration of respiratory distress. This is the first report describing the treatment of pulse methylprednisolone therapy in fatal adenovirus pneumonia. During the clinical course, serum Krebs von den Lungen-6 (KL-6), which is a marker for the activity of diffuse interstitial lung disease, was elevated, suggesting that serum KL-6 could be available as a marker of pulmonary prognosis in viral pneumonia.
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PMID:Pulse methylprednisolone therapy in type 3 adenovirus pneumonia with hypercytokinemia. 1663 25


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