http://hdl.handle.net/20.500.12701/1778 The American Journal of Physiology-Lung Cellular and Molecular Physiology publishes original research covering the broad scope of molecular, cellular, and integrative aspects of normal and abnormal function of cells and components of the respiratory system. Fri, 03 May 2024 12:19:35 GMT 2024-05-03T12:19:35Z http://hdl.handle.net/20.500.12701/1873 Название: Neither fibrin nor plasminogen activator inhibitor-1 deficiency protects lung function in a mouse model of acute lung injury Авторы: Allen, Gilman B.; Cloutier, Mary E.; Larrabee, Yuna C.; Tetenev, Konstantin; Smiley, Stephen T.; Bates, Jason H. T. Краткий осмотр (реферат): Fibrin impairs surfactant function in vitro, and inhibition of fibrinolysis by plasminogen activator inhibitor (PAI-1) is thought to promote fibrin accumulation in acute lung injury (ALI). This has led to speculation that impaired PAI-1 and fibrin accumulation should protect lung function in ALI. We tested this hypothesis by investigating ALI severity in fibrinogen-deficient (Fgn−/−) and PAI-1-deficient (PAI-1−/−) mice. PAI-1−/−, C57BL/6, Fgn−/−, and Fgn+/− females were anesthetized and allowed to aspirate 4 μl/g of hydrochloric acid (pH 1.0) and then reanesthetized and connected to a ventilator 48 h later. Naive C57BL/6 and Fgn+/− females served as controls. Following deep inflation (DI), forced oscillations were delivered periodically over 8 min to measure changes in elastance (H) as a surrogate of lung derecruitment, at positive end-expiratory pressures (PEEP) of 6, 3, and 1 cmH2O. Increases in H following DI in acid-injured mice were greater than naive strain-matched controls. Increases in H were no different between injured PAI-1−/− and C57BL/6, or between injured Fgn−/− and +/− mice, at any PEEP. Pressure-volume curves were no different between injured groups. Total lung fibrin was lower in injured PAI-1−/− and Fgn−/− mice relative to injured C57BL/6 and Fgn+/− mice, respectively, but indices of permeability were no different between strains. Unexpectedly, neither fibrin nor PAI-1 deficiency protects lung mechanical function in mice with acid-induced ALI. We speculate that in vivo lung function may be more closely tied to permeability and alveolar protein in general, rather than being linked specifically to fibrin. Acute lung injury (ALI) is a severe form of noncardiogenic pulmonary edema and hypoxemic respiratory failure stemming from numerous causes (60). Current treatment of ALI rests largely on supportive care with mechanical ventilation, and its prognosis remains poor with a mortality of 30–40% in the general population, and higher in the elderly (49). The pathology of ALI typically progresses through an initial exudative phase characterized by neutrophil infiltration, edema, and accumulation of hyaline membranes, the latter consisting primarily of necrotic debris and fibrin (58). In this regard, the coagulation pathway and its end product fibrin have excited particular interest, in part due to the ability of fibrin to inhibit surfactant function in vitro (52, 54), and the increasingly recognized interplay between coagulation and innate immunity (17, 63). Fibrin formation and clearance in the lung are governed by the relative quantity and activity of fibrinolysis promoters such as plasminogen activators and fibrinolysis inhibitors such as plasminogen activator inhibitor-1 (PAI-1) (28). The importance of PAI-1 in ALI pathogenesis is suggested by its upregulation in various ALI models (5, 7) and by the finding that PAI-1-deficient mice fail to accumulate alveolar fibrin and die less quickly in response to injury (8). The importance of PAI-1 in ALI is further underscored by the finding that elevated plasma and edema fluid levels of PAI-1 are associated with higher mortality in ALI patients (45, 61). In agreement with the widely speculated role for PAI-1 and fibrin in the impairment of lung function in ALI, we demonstrated that progressive derangement in lung mechanics over 48 h in mice with acid aspiration injury corresponds with an increase in air space PAI-1 and fibrin (5). Although implied by our findings, the direct roles of fibrin accumulation and its clearance, as governed by PAI-1, in the derangement of in vivo lung mechanical function has yet to be firmly established. We thus set out to ascertain the direct roles of PAI-1 and air space fibrin in the disruption of lung mechanical function in an acid-aspiration model of ALI among varying strains of mice with different capacities to generate fibrin or PAI-1. Among these different strains, and their respective controls, we examined the effects of acid aspiration on lung mechanical derangement, various markers of injury, and on the accumulation of fibrin and fibrin breakdown products within the lung. Sun, 01 Mar 2009 00:00:00 GMT http://hdl.handle.net/20.500.12701/1873 2009-03-01T00:00:00Z http://hdl.handle.net/20.500.12701/1811 Название: Synergy between acid and endotoxin in an experimental model of aspiration-related lung injury progression Авторы: Tetenev, Konstantin; Cloutier, Mary E.; von Reyn, Jessica A.; Ather, Jennifer L.; Candon, James; Allen, Gilman B. Краткий осмотр (реферат): Aspiration is a common cause of lung injury, but it is unclear why some cases are self-limited while others progress to acute respiratory distress syndrome (ARDS). Sporadic exposure to more than one insult could account for this variable progression. We investigated whether synergy between airway acid and endotoxin (LPS) amplifies injury severity in mice and whether LPS levels in human patients could corroborate our experimental findings. C57BL/6 mice aspirated acid (pH 1.3) or normal saline (NS), followed by LPS aerosol or nothing. Bronchoalveolar lavage fluid (BALF) was obtained 2 to 49 h later. Mice were injected with FITC-dextran 25 h after aspiration and connected to a ventilator, and lung elastance (H) measured periodically following deep inflation (DI). Endotracheal and gastric aspirates were also collected from patients in the intensive care unit and assayed for pH and LPS. Lung instability (ΔH following DI) and pressure-volume hysteresis in acid- or LPS-exposed mice was greater than in controls but markedly greater in the combined acid/LPS group. BALF neutrophils, cytokines, protein, and FITC-dextran in the acid/LPS mice were geometrically higher than all other groups. BALF from acid-only mice markedly amplified LPS-induced TNF-α production in cultured macrophages. Human subjects had variable endotracheal LPS levels with the highest burden in those at higher risk of aspiration. Acid aspiration amplifies LPS signaling in mice to disrupt barrier function and lung mechanics in synergy. High variation in airway LPS and greater airway LPS burden in patients at higher risk of aspiration could help explain the sporadic progression of aspiration to ARDS. Sun, 15 Nov 2015 00:00:00 GMT http://hdl.handle.net/20.500.12701/1811 2015-11-15T00:00:00Z http://hdl.handle.net/20.500.12701/1779 Название: Regulation of myofibroblast differentiation by cardiac glycosides Авторы: La, Jennifer; Reed, Eleanor B.; Koltsova, Svetlana; Akimova, Olga; Hamanaka, Robert B.; Mutlu, Gökhan M.; Orlov, Sergei N.; Dulin, Nickolai O. Краткий осмотр (реферат): Myofibroblast differentiation is a key process in pathogenesis of fibrotic diseases. Cardiac glycosides (ouabain, digoxin) inhibit Na+-K+-ATPase, resulting in increased intracellular [Na+]-to-[K+] ratio in cells. Microarray analysis suggested that increased intracellular [Na+]/[K+] ratio may promote the expression of cyclooxygenase-2 (COX-2), a critical enzyme in the synthesis of prostaglandins. Given antifibrotic effects of prostaglandins through activation of protein kinase A (PKA), we examined if cardiac glycosides stimulate COX-2 expression in human lung fibroblasts and how they affect myofibroblast differentiation. Ouabain stimulated a profound COX-2 expression and a sustained PKA activation, which was blocked by COX-2 inhibitor or by COX-2 knockdown. Ouabain-induced COX-2 expression and PKA activation were abolished by the inhibitor of the Na+/Ca2+ exchanger, KB-R4943. Ouabain inhibited transforming growth factor-β (TGF-β)-induced Rho activation, stress fiber formation, serum response factor activation, and the expression of smooth muscle α-actin, collagen-1, and fibronectin. These effects were recapitulated by an increase in intracellular [Na+]/[K+] ratio through the treatment of cells with K+-free medium or with digoxin. Although inhibition of COX-2 or of the Na+/Ca2+ exchanger blocked ouabain-induced PKA activation, this failed to reverse the inhibition of TGF-β-induced Rho activation or myofibroblast differentiation by ouabain. Together, these data demonstrate that ouabain, through the increase in intracellular [Na+]/[K+] ratio, drives the induction of COX-2 expression and PKA activation, which is accompanied by a decreased Rho activation and myofibroblast differentiation in response to TGF-β. However, COX-2 expression and PKA activation are not sufficient for inhibition of the fibrotic effects of TGF-β by ouabain, suggesting that additional mechanisms must exist. Sun, 01 May 2016 00:00:00 GMT http://hdl.handle.net/20.500.12701/1779 2016-05-01T00:00:00Z