Administration of a synthetic antiprotease reduces smoke-induced lung injury.

Our previous studies suggest that a neutrophil-mediated inflammatory injury causes a major fraction of the pulmonary edema that occurs after smoke inhalation. Because activated neutrophils extrude cytotoxic proteases, the current study was conducted to evaluate the role of proteases in the pulmonary microvascular injury. Twelve sheep, instrumented for collection of lung lymph, were insufflated with cotton smoke. The sheep were treated 30 min after smoke inhalation with either gabexate mesilate (an inhibitor of serine proteases) or vehicle. Smoke inhalation resulted in an increased protease activity in the lung interstitium, as evidenced by decreases in both antiprotease activity and immunoreactive alpha 2-macroglobulin. Intravenous infusion of gabexate mesilate prevented the decrease in antiprotease activity. The protease inhibitor significantly attenuated the smoke-induced increase in transvascular fluid and protein flux, with untreated animals exhibiting 460% increases in flux compared with 180% in the inhibitor treated sheep. The protease inhibitor also eliminated the functional degradation in gas exchange that was observed in the untreated sheep. These studies strongly suggest that an increase in pulmonary proteolytic enzyme activity is responsible for a significant fraction of the degradation in microvascular integrity and gas exchange that is associated with smoke inhalation injury.     

Salvage of ischemic rabbit ear by BW-755C and steroids, but not by indomethacin

The effects of anti-inflammatory steroids and BW-755C (both of which inhibit the formation of prostaglandins and leukotrienes) were studied in ischemia-induced edema and necrosis of the rabbit ear utilizing an occlusion reperfusion model. The results were compared with cyclooxygenase inhibitors which selectively block the synthesis of prostaglandins without affecting leukotriene production. Significant inhibition of the progression of necrosis was observed with both methyl prednisolone and BW-755C. The cyclooxygenase inhibitors, naproxen and low-dose indomethacin had no effect on the progression of ear necrosis. By contrast, high-dose indomethacin significantly inhibited edema but accelerated the progression of necrosis.     

Salvage of ischemic rabbit ear by BW-755C and steroids, but not by indomethacin

The effects of anti-inflammatory steroids and BW-755C (both of which inhibit the formation of prostaglandins and leukotrienes were studied in ischemia-induced edema and necrosis of the rabbit ear utilizing an occlusion reperfusion model. The results were compared with cyclooxygenase inhibitors which selectively block the synthesis of prostaglandins without affecting leukotriene production.Significant inhibition of the progression of necrosis was observed with both methyl prednisolone and BW-755C. The cyclooxygenase inhibitors, naproxen and low-dose indomethacin had no effect on the progression of ear necrosis. By contrast, high-dose indomethacin significantly inhibited edema but accelerated the progression of necrosis.     

Cyclooxygenase pathway mediates lung injury induced by phorbol and platelets

The role of platelets in lung injury has not been well defined. In the present study of isolated perfused rat lungs, phorbol myristate acetate (PMA; 0.15 microgram/ml) or platelets (6.7 X 10(4)/ml) alone did not discernibly change the pulmonary arterial pressure (PAP) or lung weight (LW). However, the combination of platelets and PMA drastically increased the PAP and LW (delta PAP 26.2 +/- 1.0 mmHg, delta LW 2.7 +/- 0.4 g). delta PAP was positively correlated with the increase in thromboxane B2 produced by infusion of platelets and PMA (thromboxane B2 = 35.6 + 0.97 delta PAP, r = 0.67, P less than 0.01). The hypertension and edema formation induced by PMA and platelets were strongly attenuated by indomethacin, an inhibitor of platelet cyclooxygenase (delta PAP 5.6 +/- 2.0 mmHg, P less than 0.001; delta LW 0.0 +/- 0.1 g, P less than 0.001), and by imidazole, an inhibitor of thromboxane A2 synthase (PAP 8.0 +/- 2.5 mmHg, P less than 0.001; LW 0.0 +/- 0.3 g, P less than 0.01). Inactivation of platelet lipoxygenase with nordihydroguaiaretic acid mildly depressed pulmonary pressure but did not affect delta LW (delta PAP 18.9 +/- 1.6 mmHg, P less than 0.05; delta LW 3.1 +/- 0.3 g, P greater than 0.05). In vitro experiments showed that the capacity of platelets to release oxygen radicals was only 2.6% of that found for granulocytes. These results suggest that platelets may be activated by PMA to increase PAP and vascular permeability.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cyclooxygenase 2 plays a pivotal role in the resolution of acute lung injury

Acute lung injury (ALI) is a severe illness with excess mortality and no specific therapy. In its early exudative phase, neutrophil activation and accumulation in the lung lead to hypoxemia, widespread tissue damage, and respiratory failure. In clinical trials, inhibition of proinflammatory mediators has not proven effective. In this study, we pursued a new investigative strategy that emphasizes mediators promoting resolution from lung injury. A new spontaneously resolving experimental murine model of ALI from acid aspiration was developed to identify endogenous proresolving mechanisms. ALI increased cyclooxygenase 2 (COX-2) expression in murine lung. Selective pharmacologic inhibition or gene disruption of COX-2 blocked resolution of ALI. COX-2-derived products increased levels of the proresolving lipid mediators lipoxin A4 (LXA4) and, in the presence of aspirin, 15-epi-LXA4. Both LXA4 and 15-epi-LXA4 interact with the LXA4 receptor (ALX) to mediate anti-inflammatory actions. ALX expression was markedly induced by acid injury and transgenic mice with increased ALX expression displayed dramatic protection from ALI. Together, these findings indicate a protective role in ALI for COX-2-derived mediators, in part via enhanced lipoxin signaling, and carry potential therapeutic implications for this devastating clinical disorder.     

Thalidomide reduces lipopolysaccharide/zymosan-induced acute lung injury in rats

Pharmacological therapies targeting fulminant lung inflammation in acute lung injury (ALI) need to be improved. We evaluated the effect of thalidomide, a chemical modulating both acute and chronic inflammation, on ALI induced by intravenous administration of lipopolysaccharide (LPS) and zymosan in male Sprague-Dawley rats. Injection of LPS and zymosan induced significant lung inflammation, as evidenced by increased neutrophil sequestration in lung tissue as well as enhanced nitric oxide metabolite (NO _x ^– ) production in the serum and bronchoalveolar lavage (BAL) fluid. Lactate dehydrogenase (LDH) activity and protein concentration in BAL fluid were significantly increased after administration of LPS and zymosan. Pulmonary microvascular permeability was determined using the Evans blue retention method, which showed a significant increase in microvascular permeability after LPS and zymosan administration, indicating the development of ALI. Animals that received thalidomide (100 mg/kg) 2 h prior to LPS injection had significantly reduced pulmonary NO _x ^– production, pulmonary microvascular permeability, and LDH activity and protein concentration in BAL fluid. We therefore conclude that thalidomide ameliorates lung inflammation and reduces ALI induced by combined LPS and zymosan administration in rats.     

Green tea extract supplement reduces D-galactosamine-induced acute liver injury by inhibition of apoptotic and proinflammatory signaling

Oxidative stress and inflammation contributed to the propagation of acute liver injury (ALI). The present study was undertaken to determine whether D-galactosamine (D-GalN) induces ALI via the mitochondrial apoptosis- and proinflammatory cytokine-signaling pathways, and possible mechanism(s) by which green tea (GT) extract modulates the apoptotic and proinflammatory signaling in rat. D-GalN induced hepatic hypoxia/hypoperfusion and triggered reactive oxygen species (ROS) production from affected hepatocytes, infiltrated leukocytes, and activated Kupffer cells. D-GalN evoked cytosolic Bax and mitochondrial cytochrome C translocation and activated proinflammatory nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1) translocation, contributing to the increase of intercellular adhesion molecule-1 expression, terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL)-positive hepatocytes, multiple plasma cytokines and chemokines release, and alanine aminotransferase (ALT) activity. An altered biliary secretion profile of several acute phase proteins directly indicates oxidative stress affecting intracellular trafficking in the hepatocyte. GT pretreatment attenuated ROS production, mitochondrial apoptosis- and proinflammatory cytokine-signaling pathway, plasma ALT and cytokines levels, biliary acute phase proteins secretion and hepatic pathology by the enhancement of anti-apoptotic mechanisms. In conclusion, D-GalN induced ALI via hypoxia/hypoperfusion-enhanced mitochondrial apoptosis- and proinflammatory cytokine-signaling pathway, contributing to oxidative stress and inflammation in the liver. GT can counteract the D-GalN-induced ALI via the attenuation of apoptotic and proinflammatory signaling by the upregulation of anti-apoptotic mechanism.     

Protein C and thrombomodulin in human acute lung injury

Decreased circulating protein C and increased circulating thrombomodulin are markers of the prothrombotic, antifibrinolytic state associated with poor outcomes in sepsis but have not been measured in patients with ALI (acute lung injury)/ARDS (acute respiratory distress syndrome). We measured circulating and intra-alveolar protein C and thrombomodulin in 45 patients with ALI/ARDS from septic and nonseptic causes and correlated the levels with clinical outcomes. Plasma protein C levels were lower in ALI/ARDS compared with normal. Lower levels of protein C were associated with worse clinical outcomes, including death, fewer ventilator-free days, and more nonpulmonary organ failures, even when only patients without sepsis were analyzed. Levels of thrombomodulin in pulmonary edema fluid from ALI/ARDS patients were >10-fold higher than normal plasma and 2-fold higher than ALI/ARDS plasma. Higher edema fluid thrombomodulin levels were associated with worse clinical outcomes. The higher levels in edema fluid compared with plasma suggest local release of soluble thrombomodulin in the lung, possibly from a lung epithelial source. To determine whether lung epithelial cells can release thrombomodulin, A549 cells and primary isolates of human alveolar type II cells were exposed to H2O2 or inflammatory cytokines. Both epithelial cell types released thrombomodulin into the media. In summary, the protein C system is markedly disrupted in patients with ALI/ARDS from both septic and nonseptic causes. The protein C system may be a potential therapeutic target in patients with ALI/ARDS.     

Molecular and cellular mechanisms of cigarette smoke-induced myocardial injury: prevention by vitamin C

Background

Cardiovascular disease (CVD) remains one of the major killers in modern society. One strong risk factor of CVD is cigarette smoking that causes myocardial injury and leads to the genesis of pathological cardiovascular events. However, the exact toxic component(s) of cigarette smoke (CS) and its molecular and cellular mechanisms for causing myocardial injury leading to heart damage and its prevention are largely unknown.

Methodology/Principal Findings

Using a guinea pig model, here we show that chronic exposure to CS produces myocardial injury that is prevented by vitamin C. Male guinea pigs were fed either vitamin C-deficient (0.5 mg/day) or vitamin C-sufficient (15 mg/day) diet and subjected to CS exposure from 5 Kentucky Research cigarettes (3R4F)/day (6 days/week) in a smoke chamber up to 8 weeks. Pair-fed sham controls were subjected to air exposure instead of CS exposure under similar conditions. Myocardial injury was produced in CS-exposed marginal vitamin C-deficient guinea pigs as evidenced by release of cardiac Troponin-T and I in the serum, oxidative stress, inflammation, apoptosis, thrombosis and collagen deposition in the myocardium. Treatment of rat cardiomyocyte cells (H9c2) in vitro and guinea pigs in vivo with p-benzoquinone (p-BQ) in amounts derived from CS revealed that p-BQ was a major factor responsible for CS-induced myocardial damage. A moderately large dose of vitamin C (15 mg/day) prevented CS/p-BQ-induced myocardial injury. Population based studies indicated that plasma vitamin C levels of smokers without disease were significantly lower (p = 0,0000) than that of non-smokers. Vitamin C levels of CS-related cardiovascular patients were further lower (p = 0.0000) than that of smokers without disease.

Conclusions/Significance

The results indicate that dietary supplementation of vitamin C may be a novel and simple therapy for the prevention of pathological cardiovascular events in habitual smokers.     

Immature lung and acute lung injury

Acute lung injury occurs mostly in the very low birth weight and extremely low birth weight infants. The pathological process leading to acute lung injury includes immature and/or diseased lung that experienced oxidative stress, inflammation and mechanical insult with the bronchial, alveolar and capillary injuries and cell death. It may be the first step to the subsequent development of chronic lung disease of prematurity or bronchopulmonary dysplasia. The mechanisms of lung injury are extensively investigated in the experimental models and clinical studies, mostly performed on the adult patients. At present, the explanations of the mechanism(s) leading to lung tissue injury in tiny premature babies are just derived from these studies. Acute lung injury seems to be rather a syndrome than a well-defined nosological unit and is of multifactorial etiology. The purpose of this review is to discuss the main factors contributing to the development of acute lung injury in the very low or extremely low birth weight infants--lung immaturity, mechanical injury, oxidative stress and inflammation. Nevertheless, numerous other factors may influence the status of immature lung after delivery.     

Effect of cyclooxygenase inhibition on ethchlorvynol-induced acute lung injury in dogs

In anesthetized dogs ethchlorvynol (ECV, 9 mg/kg) was selectively administered into the right pulmonary circulation to produce unilateral acute lung injury (ALI) characterized by nonhydrostatic pulmonary edema and systemic hypoxemia. To investigate the hypothesis that products of cyclooxygenase activity are mediators of the arterial hypoxemia, but not the edema formation in this injury, animals were pretreated with one of two chemically dissimilar cyclooxygenase inhibitors, indomethacin (5 mg/kg), or ibuprofen (12.5 mg/kg), or vehicle (0.1 M sodium carbonate) prior to the administration of ECV. Pretreatment with either inhibitor prevented the ECV-induced systemic hypoxemia observed in animals pretreated with vehicle (P less than 0.01). Despite this protection of systemic oxygenation, there was no redistribution of blood flow to the uninjured lung following unilateral ECV administration. Cyclooxygenase inhibition prior to ALI did not attenuate the accumulation of lung water. In the ibuprofen group, left atrial pressure increased significantly following ECV administration. We conclude that a product(s) of cyclooxygenase-mediated arachidonic acid metabolism is responsible for the altered vascular reactivity and consequent systemic hypoxemia in this model, but that the edema formation following ECV is not related to cyclooxygenase activity. In addition, ibuprofen, administered prior to the induction of ALI, exhibits properties not shared by indomethacin but is not different in its capacity to attenuate hypoxemia or in its failure to limit edema formation.     

Cyclooxygenase and lipoxygenase metabolite synthesis by polymorphonuclear neutrophils: in vitro effect of dipyrone

Functional activity of polymorphonuclear neutrophils (PMN) is associated with the metabolism of Arachidonic Acid (AA) released from membrane phospholipids. In this study the in vitro effect of dipyrone, a non steroidal anti-inflammatory drug, on the production of AA metabolites through cyclooxygenase (CO) and lipoxygenase (LO) pathways by stimulated PMN has been investigated. PMN isolated by counterflow centrifuge elutriator were greater than 98% pure and viable. Metabolite production was evaluated by RIA of Thromboxane A2 (TxA2), Prostaglandin E2 (PGE2), Leukotriene B2 (LTB4) and Leukotriene C4 (LTC4) after PMN stimulation with calcium ionophore A 23187 (20 microM). The levels of beta-thromboglobulin (RIA) lower than 5 ng/ml allowed us to rule out activation of residual contaminant platelets. In these experimental conditions, in the absence of dipyrone the products (ng/10(6) cells) of AA metabolism were LTB4 (3.51 +/- 0.22), LTC4 (0.81 +/- 0.08), TxB2 (0.144 +/- 0.025) and PGE2 (0.150 +/- 0.017). Incubation with dipyrone induced changes of PGE2 and TXB2 production in a dose dependent fashion (r = 0.83 and r = 0.87, p less than 0.001), obtaining already at the lowest drug concentration (5 micrograms/ml) a significant inhibition (33 and 40% for TxB2 and PGE2 p less than 0.005). No significant changes of LTB4 and LTC4 production have been observed. The results of this study indicate that dipyrone relevantly affects CO metabolite synthesis by stimulated PMN at concentrations comparable to those reached in therapeutic use. The inhibition of PGE2 synthesis which is present in inflamed tissues and actively participates in inflammatory reactions, could contribute to the therapeutic anti-inflammatory action of dipyrone.     

Ethyl pyruvate reduces mortality in an endotoxin-induced severe acute lung injury mouse model

Background

Desmosine and Isodesmosine (D/I) are cross-linking amino acids which are present only in mature elastin. Changes in their concentration in body fluids indicate changes in elastin degradation and can be a reflection of tissue elastase activity. This study was undertaken to determine whether continuous therapy with the long-acting bronchodilator Tiotropium bromide (TTP) could result in reductions in D/I as measured by mass spectrometry in plasma, urine and sputum.

Methods

Twelve not currently smoking patients with chronic obstructive pulmonary disease (COPD), never on TTP, were selected for study. Levels of D/I, along with measurements of FVC, FEV₁ and FEV₁/FVC. were determined before starting TTP daily, and then one and two months after.

Results

D/I decreased in plasma (10 of 12 patients), in sputum all (12 of 12), and in the percentage of free D/I in urine (10 of 12). Most patients showed slight increases in FVC and FEV₁ percent predicted over two months.

Conclusion

The results are consistent with an effect of prolonged bronchodilitation by anti-cholinergic blockade to also result in reduced lung elastin degradation.     

A multi-target antisense approach against PDE4 and PDE7 reduces smoke-induced lung inflammation in mice

Background

Recent development in the field of COPD has focused on strategies aimed at reducing the underlying inflammation through selective inhibition of the phosphodiesterase type IV (PDE4) isoform. Although the anti-inflammatory and bronchodilator activity of selective PDE4 inhibitors has been well documented, their low therapeutic ratio and dose-dependent systemic side effects have limited their clinical utility. This study examined the effect of 2''-deoxy-2''-Fluoro-β-D-Arabinonucleic Acid (FANA)-containing antisense oligonucleotides (AON) targeting the mRNA for the PDE4B/4D and 7A subtypes on lung inflammatory markers, both in vitro and in vivo.

Methods

Normal human bronchial epithelial (NHBE) cells were transfected with FANA AON against PDE4B/4D and 7A alone or in combination. mRNA levels for target PDE subtypes, as well as secretion of pro-inflammatory chemokines were then measured following cell stimulation. Mice were treated with combined PDE4B/4D and 7A AON via endo-tracheal delivery, or with roflumilast via oral delivery, and exposed to cigarette smoke for one week. Target mRNA inhibition, as well as influx of inflammatory cells and mediators were measured in lung lavages. A two-week smoke exposure protocol was also used to test the longer term potency of PDE4B/4D and 7A AONs.

Results

In NHBE cells, PDE4B/4D and 7A AONs dose-dependently and specifically inhibited expression of their respective target mRNA. When used in combination, PDE4B/4D and 7A AONs significantly abrogated the cytokine-induced secretion of IL-8 and MCP-1 to near baseline levels. In mice treated with combined PDE4B/4D and 7A AONs and exposed to cigarette smoke, significant protection against the smoke-induced recruitment of neutrophils and production of KC and pro-MMP-9 was obtained, which was correlated with inhibition of target mRNA in cells from lung lavages. In this model, PDE AONs exerted more potent and broader anti-inflammatory effects against smoke-induced lung inflammation than roflumilast. Moreover, the protective effect of PDE4B/4D and 7A AON was maintained when a once-weekly treatment schedule was used.

Conclusion

These results indicate that inhaled AON against PDE4B/4D and 7A have unique effects on biomarkers that are believed to be important in the pathophysiology of COPD, which supports further development as a potential therapy in this disease.     

Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

Background

The association between bronchial obstruction severity and mortality in Chronic Obstructive Pulmonary Disease (COPD) is well established, but it is unknown whether disease-specific health status measures and multidimensional assessment (MDA) have comparable prognostic value.

Methods

We analyzed data coming from the Salute Respiratoria nell'Anziano (Respiratory Health in the Elderly – SaRA) study, enrolling elderly people attending outpatient clinics for respiratory and non-respiratory problems. From this population we selected 449 patients with bronchial obstruction (77.3% men, mean age 73.1). We classified patients' health status using tertiles of the Saint George Respiratory Questionnaire (SGRQ) and a MDA including functional (the 6' walking test, WT), cognitive (Mini-Mental State Examination, MMSE) and affective status (Geriatric Depression Scale, GDS). The agreement of the classification methods was calculated using the kappa statistic, and survival associated with group membership was evaluated using survival analysis.

Results

Pulmonary function, expressed by the FEV1, worsened with increasing SGRQ or MDA scores. Cognitive function was not associated with the SGRQ, while physical performance and mood status were impaired only in the highest tertile of SGRQ. A poor agreement was found between the two classification systems tested (k = 0.194). Compared to people in the first tertile of SGRQ score, those in the second tertile had a sex-adjusted HR of 1.22 (0.75 – 1.98) and those in the third tertile of 2.90 (1.92 – 4.40). The corresponding figures of the MDA were 1.49 (95% CI 1.02 – 2.18) and 2.01 (95% CI: 1.31 – 3.08). After adjustment for severity of obstruction, only a SGRQ in the upper tertile was associated with mortality (HR: 1.86; 95% CI: 1.14 – 3.02).

Conclusion

In elderly outpatients with mild-moderate COPD, a disease-specific health status index seems to be a better predictor of death compared to a MDA.