Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and LTB4 expression

Role of Platelet Activating Factor as a Mediator of Inflammatory Diseases and Preterm Delivery

Nearly 70% of preterm deliveries occur spontaneously, and the clinical pathways involved include preterm labor and preterm premature rupture of membranes. Prediction of preterm delivery is considered crucial due to the significant effects of preterm birth on health and the economy at both the personal and community levels. Although similar inflammatory processes occur in both term and preterm delivery, the premature activation of these processes or exaggerated inflammatory response triggered by infection or sterile factors leads to preterm delivery. Platelet activating factor (PAF) is a phosphoglycerylether lipid mediator of inflammation that is implicated in infections, cancers, and various chronic diseases and disorders including cardiovascular, renal, cerebrovascular, and central nervous system diseases. In gestational tissues, PAF mediates the inflammatory pathways that stimulate the effector mechanisms of labor, including myometrial contraction, cervical dilation, and fetal membrane rupture. Women with preterm labor and preterm premature rupture of membranes have increased levels of PAF in their amniotic fluid. In mice, the intrauterine or intraperitoneal administration of carbamyl PAF activates inflammation in gestational tissues, thereby eliciting preterm delivery. This review summarizes recent research on PAF as an important inflammatory mediator in preterm delivery and in other inflammatory disorders, highlighting its potential value for prediction, intervention, and prevention of these diseases.

Neutrophil-Derived Proteases in Lung Inflammation: Old Players and New Prospects

Neutrophil-derived proteases are critical to the pathology of many inflammatory lung diseases, both chronic and acute. These abundant enzymes play roles in key neutrophil functions, such as neutrophil extracellular trap formation and reactive oxygen species release. They may also be released, inducing tissue damage and loss of tissue function. Historically, the neutrophil serine proteases (NSPs) have been the main subject of neutrophil protease research. Despite highly promising cell-based and animal model work, clinical trials involving the inhibition of NSPs have shown mixed results in lung disease patients. As such, the cutting edge of neutrophil-derived protease research has shifted to proteases that have had little-to-no research in neutrophils to date. These include the cysteine and serine cathepsins, the metzincins and the calpains, among others. This review aims to outline the previous work carried out on NSPs, including the shortcomings of some of the inhibitor-orientated clinical trials. Our growing understanding of other proteases involved in neutrophil function and neutrophilic lung inflammation will then be discussed. Additionally, the potential of targeting these more obscure neutrophil proteases will be highlighted, as they may represent new targets for inhibitor-based treatments of neutrophil-mediated lung inflammation.

DEL-1, as an anti-neutrophil transepithelial migration molecule, inhibits airway neutrophilic inflammation in asthma

BACKGROUND

Neutrophil migration into the airways is a key process in neutrophilic asthma. Developmental endothelial locus-1 (DEL-1), an extracellular matrix protein, is a neutrophil adhesion inhibitor that attenuates neutrophilic inflammation.

METHODS

Levels of DEL-1 were measured in exhaled breath condensate (EBC) and serum in asthma patients by ELISA. DEL-1 modulation of neutrophil adhesion and transepithelial migration was examined in a co-culture model in vitro. The effects of DEL-1-adenoviral vector-mediated overexpression on ovalbumin/lipopolysaccharide (OVA/LPS)-induced neutrophilic asthma were studied in mice in vivo.

RESULTS

DEL-1 was primarily expressed in human bronchial epithelial cells and was decreased in asthma patients. Serum DEL-1 concentrations were reduced in patients with severe asthma compared with normal subjects (567.1 ± 75.3 vs. 276.8 ± 29.36 pg/mL, p < .001) and were negatively correlated to blood neutrophils (r = -0.2881, p = .0384) and neutrophil-to-lymphocyte ratio (NLR) (r = -0.5469, p < .0001). DEL-1 concentrations in the EBC of severe asthmatic patients (113.2 ± 8.09 pg/mL) were also lower than normal subjects (193.0 ± 7.61 pg/mL, p < .001) and were positively correlated with the asthma control test (ACT) score (r = 0.3678, p = .0035) and negatively related to EBC IL-17 (r = -0.3756, p = .0131), myeloperoxidase (MPO) (r = -0.5967, p = .0055), and neutrophil elastase (NE) (r = -0.5488, p = .0009) expression in asthma patients. Neutrophil adhesion and transepithelial migration in asthma patients were associated with LFA-1 binding to ICAM-1 and inhibited by DEL-1. DEL-1 mRNA and protein expression in human bronchial epithelial cells were regulated by IL-17. Exogenous DEL-1 inhibited IL-17-enhanced neutrophil adhesion and migration. DEL-1 expression was decreased while neutrophil infiltration was increased in the airway of a murine model of neutrophilic asthma. This was prevented by DEL-1 overexpression.

CONCLUSIONS

DEL-1 down-regulation leads to increased neutrophil migration across bronchial epithelial cells and is associated with neutrophilic airway inflammation in asthma.

Neutrophils as emerging protagonists and targets in chronic inflammatory diseases

INTRODUCTION

Neutrophils are the key cells of our innate immune system with a primary role in host defense. They rapidly arrive at the site of infection and display a range of effector functions including phagocytosis, degranulation, and NETosis to eliminate the invading pathogens. However, in recent years, studies focusing on neutrophil biology have revealed the highly adaptable nature and versatile functions of these cells which extend beyond host defense. Neutrophils are now referred to as powerful mediators of chronic inflammation. In several chronic inflammatory diseases, their untoward actions, such as immense infiltration, hyper-activation, dysregulation of effector functions, and extended survival, eventually contribute to disease pathogenesis. Therefore, a better understanding of neutrophils and their effector functions in prevalent chronic diseases will not only shed light on their role in disease pathogenesis but will also reveal them as novel therapeutic targets.

METHODS

We performed a computer-based online search using the databases, PubMed.gov and Clinical trials.gov for published research and review articles.

RESULTS AND CONCLUSIONS

This review provides an assessment of neutrophils and their crucial involvement in various chronic inflammatory disorders ranging from respiratory, neurodegenerative, autoimmune, and cardiovascular diseases. In addition, we also discuss the therapeutic approach for targeting neutrophils in disease settings that will pave the way forward for future research.

Emerging Roles of Platelets in Allergic Asthma

Allergic asthma is a complex chronic inflammatory disease of the airways, driven by Th2 immune responses and characterized by eosinophilic pulmonary inflammation, airway hyperresponsiveness, excessive mucus production, and airway remodeling. Overwhelming evidence from studies in animal models and allergic asthmatic patients suggests that platelets are aberrantly activated and recruited to the lungs. It has been established that platelets can interact with other immune cells and secrete various biochemical mediators to promote allergic sensitization and airway inflammatory response, and platelet deficiency may alleviate the pathological features and symptoms of allergic asthma. However, the comprehensive roles of platelets in allergic asthma have not been fully clarified, leaving attempts to treat allergic asthma with antiplatelet agents questionable. In this review, we summarize the role of platelet activation and pulmonary accumulation in allergic asthma; emphasis is placed on the different interactions between platelets with crucial immune cell types and the contribution of platelet-derived mediators in this context. Furthermore, clinical antiplatelet approaches to treat allergic asthma are discussed. This review provides a clearer understanding of the roles of platelets in the pathogenesis of allergic asthma and could be informative in the development of novel strategies for the treatment of allergic asthma.

Mapping atopic dermatitis and anti-IL-22 response signatures to type 2-low severe neutrophilic asthma

BACKGROUND

Transcriptomic changes in patients who respond clinically to biological therapies may identify responses in other tissues or diseases.

OBJECTIVE

We sought to determine whether a disease signature identified in atopic dermatitis (AD) is seen in adults with severe asthma and whether a transcriptomic signature for patients with AD who respond clinically to anti-IL-22 (fezakinumab [FZ]) is enriched in severe asthma.

METHODS

An AD disease signature was obtained from analysis of differentially expressed genes between AD lesional and nonlesional skin biopsies. Differentially expressed genes from lesional skin from therapeutic superresponders before and after 12 weeks of FZ treatment defined the FZ-response signature. Gene set variation analysis was used to produce enrichment scores of AD and FZ-response signatures in the Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes asthma cohort.

RESULTS

The AD disease signature (112 upregulated genes) encompassing inflammatory, T-cell, TH2, and TH17/TH22 pathways was enriched in the blood and sputum of patients with asthma with increasing severity. Patients with asthma with sputum neutrophilia and mixed granulocyte phenotypes were the most enriched (P < .05). The FZ-response signature (296 downregulated genes) was enriched in asthmatic blood (P < .05) and particularly in neutrophilic and mixed granulocytic sputum (P < .05). These data were confirmed in sputum of the Airway Disease Endotyping for Personalized Therapeutics cohort. IL-22 mRNA across tissues did not correlate with FZ-response enrichment scores, but this response signature correlated with TH22/IL-22 pathways.

CONCLUSIONS

The FZ-response signature in AD identifies severe neutrophilic asthmatic patients as potential responders to FZ therapy. This approach will help identify patients for future asthma clinical trials of drugs used successfully in other chronic diseases.

The role of leukotrienes in allergic diseases

Leukotrienes (LTs), both LTB4 and the cysteinyl LTs (CysLTs) LTC4, LTD4 and LTE4, are implicated in a wide variety of inflammatory disorders. These lipid mediators are generated from arachidonic acid via multistep enzymatic reactions through which arachidonic acid is liberated from membrane phospholipids through the action of phospholipase A2. LTB4 and CysLTs exert their biological effects by binding to cognate receptors, which belong to the G protein-coupled receptor superfamily. LTB4 is widely considered to be a potent chemoattractant for most subsets of leukocytes, whereas CysLTs are potent bronchoconstrictors that have effects on airway remodeling. LTs play a central role in the pathogenesis of asthma and many other inflammatory diseases. This review will provide an update on the synthesis, biological function, and relevance of LTs to the pathobiology of allergic diseases, and examine the current and future therapeutic prospects of LT modifiers.

Neutrophils in asthma--a review

Asthma is a chronic inflammatory disease, with an array of cells involved in the pathogenesis of the disease. The role of neutrophils in the development of bronchial asthma is found to be complex, as they may trigger activation of immunocompetent cells and are a potent source of free oxygen radicals and enzymes participating in airway remodeling. The review highlights the role of neutrophils in bronchial asthma.

Fish oil supplementation decreases oxidative stress but does not affect platelet-activating factor bioactivity in lungs of asthmatic rats

Dietary fish oil supplementation increases the content of n-3 polyunsaturated fatty acids (PUFA) in cellular membranes. The highly unsaturated nature of n-3 PUFA could result in an enhanced lipid peroxidation in the oxidative environment characteristic of asthma. The oxidative reaction cascade culminates in an increased production of components associated to oxidative stress and of an important proinflammatory mediator platelet-activating factor (PAF)-like lipid. We evaluated the effect of fish oil supplementation in asthmatic rats upon the PAF bioactivity and parameters related to oxidative stress in the lung. Fish oil supplementation of asthmatic rats resulted in lower concentrations of nitrite (1.719 ± 0.137 vs. 2.454 ± 0.163 nmol/mL) and lipid hydroperoxide (72.190 ± 7.327 vs. 120.200 ± 11.270 nmol/mg protein). In asthmatic animals, fish oil increased the activities of superoxide dismutase (EC 1.15.1.1) (33.910 ± 2.325 vs. 24.110 ± 0.618 U/mg protein) and glutathione peroxidase (EC 1.11.1.9) (164.100 ± 31.250 vs. 12.590 ± 5.234 U/mg protein). However, fish oil did not affect PAF bioactivity in lung tissue of asthmatic rats (0.545 ± 0.098 340/380 vs. 0.669 ± 0.101 340/380 nm ratio). Considering the two-step process--oxidative stress and PAF bioactivity--fish oil exhibited a divergent action on these aspects of asthmatic inflammation, since the supplement lowered oxidative stress in the lungs of asthmatic rats, presenting an antioxidant effect, but did not affect PAF bioactivity. This suggests a dual effect of fish oil on oxidative stress and inflammation in asthma.

The role of platelet-activating factor receptor (PAFR) in lung pathology during experimental malaria

Malaria-associated lung pathology has been a neglected area in the study of malaria complications. Platelet-activating factor (PAF) is an inflammatory mediator involved in lung inflammation. Using mice lacking the PAF receptor (PAFR(-/-)) we investigated the relevance of signaling through the PAFR for the lung inflammatory process triggered by Plasmodium berghei ANKA (PbA) strain infection. In PAFR(-/-) mice, pulmonary inflammation was markedly reduced as demonstrated by histology, production of certain pro-inflammatory mediators, accumulation of macrophage and CD8+ T cells in the lung parenchyma and the virtual absence of changes in vascular permeability. Therefore, PAFR activation is crucial in the pathogenesis of pulmonary damage associated with PbA infection in C57Bl/6 mice.

Influence of sublingual immunotherapy on the expression of Mac-1 integrin in neutrophils from asthmatic children

Asthma can be effectively treated with sublingual immunotherapy. The influence of -sublingual immunotherapy on the function of granulocytes in asthmatic patients is largely unknown. Mac-1 integrin is a transmembrane protein containing α (CD11b) and β (CD18) chains. High expression of the complex is found on the surface of neutrophils, NK cells, and macrophages. CD11b/CD18 may bind to CD23, ICAM-1, ICAM-2, and ICAM-4. It plays a crucial role in diapedesis of neutrophils. The aim of the present study was to assess Mac-1 expression on neutrophils from asthmatic children before and after sublingual immunotherapy. Twenty five children aged of 8.1 ± 3.1 suffering from atopic asthma and allergic rhinitis, shortlisted for specific immunotherapy, served as the study group. Fifteen healthy individuals, aged 9.8 ± 3.4, served as a control group. The assessment of CD11b and CD18 expression on cells from peripheral blood was performed with a flow cytometer. The tests were performed before and after 12 months of sublingual immunotherapy. In the asthmatic children, 98.08 (90.79-99.12)% of Mac-1 positive neutrophils were detected. The group was divided into two subgroups: of more than 98% and less than 95% of neutrophils with CD11b/CD18 expression in the sample. After immunotherapy, the percentage of Mac-1 positive granulocytes increased to 99.60 (99.29-99.68)%, p = 0.01. In the control group, 90.56 (87.08-88.86)% granulocytes were Mac-1 positive, p = 0.002. We conclude that sublingual immunotherapy strongly influences the function of the immunological system, including Mac-1 expression on neutrophils.

Salbutamol but not ipratropium abolishes leukotriene D4-induced gas exchange abnormalities in asthma

PURPOSE

Leukotriene D(4) (LTD(4)) is a central mediator in asthma inducing bronchoconstriction and profound disturbances in pulmonary gas exchange in asthmatic subjects. The aim of the study was to compare, for the first time, the influence of the bronchodilators salbutamol (400 μg) and ipratropium (80 μg) on lung function changes induced by inhaled LTD(4).

METHODS

Treatments were evaluated in a randomized, three-period, double-blind, placebo-controlled, cross-over study where spirometric and pulmonary gas exchange indices were followed in 12 subjects with mild asthma before and after LTD(4) challenge.

RESULTS

Compared with placebo, salbutamol provided significant protection against the fall in FEV(1) (forced expiratory volume in 1 s) after LTD(4) challenge. Salbutamol also abolished the LTD(4)-induced gas exchange disturbances [decreased arterial oxygen tension (PaO(2)) and increased alveolar-arterial oxygen tension difference (AaPO(2))]. Ipratropium provided significant but less marked attenuation of the changes in FEV(1) and arterial oxygenation induced by LTD(4).

CONCLUSION

Despite the equal bronchodilatory effects of salbutamol and ipratropium before the challenge with LTD(4), salbutamol was superior to ipratropium in preventing spirometric and gas exchange abnormalities. This result indicates a broader action of salbutamol on several of the disturbances that contribute to airway obstruction including, for example, exudation of plasma in the airway mucosa. The clinical implication of this new finding is that in this model of acute asthmatic airway obstruction, salbutamol was more effective than ipratropium.

Platelet-activating factor receptor plays a role in lung injury and death caused by Influenza A in mice

Influenza A virus causes annual epidemics which affect millions of people worldwide. A recent Influenza pandemic brought new awareness over the health impact of the disease. It is thought that a severe inflammatory response against the virus contributes to disease severity and death. Therefore, modulating the effects of inflammatory mediators may represent a new therapy against Influenza infection. Platelet activating factor (PAF) receptor (PAFR) deficient mice were used to evaluate the role of the gene in a model of experimental infection with Influenza A/WSN/33 H1N1 or a reassortant Influenza A H3N1 subtype. The following parameters were evaluated: lethality, cell recruitment to the airways, lung pathology, viral titers and cytokine levels in lungs. The PAFR antagonist PCA4248 was also used after the onset of flu symptoms. Absence or antagonism of PAFR caused significant protection against flu-associated lethality and lung injury. Protection was correlated with decreased neutrophil recruitment, lung edema, vascular permeability and injury. There was no increase of viral load and greater recruitment of NK1.1⁺ cells. Antibody responses were similar in WT and PAFR-deficient mice and animals were protected from re-infection. Influenza infection induces the enzyme that synthesizes PAF, lyso-PAF acetyltransferase, an effect linked to activation of TLR7/8. Therefore, it is suggested that PAFR is a disease-associated gene and plays an important role in driving neutrophil influx and lung damage after infection of mice with two subtypes of Influenza A. Further studies should investigate whether targeting PAFR may be useful to reduce lung pathology associated with Influenza A virus infection in humans.

Influenza virus causes disease that affects people from different age, gender or social conditions. The illness spreads easily and affects millions of people every year. Vaccines are effective preventive approaches, but the high degree of viral antigenic drift requires annual formulation. Anti-viral drugs are used as therapy, but are only effective at the very early stages of disease. The main symptoms that lead to hospitalizations and deaths are associated with the severe inflammatory host immune response triggered by the virus infection. Our approach was to decrease the inflammatory events associated with the viral infection by targeting a molecule, Platelet Activating Factor receptor (PAFR), known to induce several inflammatory events, including leukocyte recruitment and leakage. We found that PAFR deficient mice or wild type mice treated with a PAFR antagonist had less pulmonary inflammation, pulmonary injury and lethality rates when infected by two subtypes of Influenza A virus. In contrast, the immune response against the virus, as assessed by viral loads and specific antibodies, were not decreased. Our findings concur with the idea that severe inflammation plays an important role in flu morbidity and mortality and show that PAFR is a major driver of the exacerbated inflammation in mice infected with Influenza A virus.

Endothelial cell prostaglandin I(2) and platelet-activating factor production are markedly attenuated in the calcium-independent phospholipase A(2)beta knockout mouse

Damage and activation of lung endothelium can lead to interstitial edema, infiltration of inflammatory cells into the interstitium and airways, and production of inflammatory metabolites, all of which propagate airway inflammation in a variety of diseases. We have previously determined that stimulation of human microvascular endothelial cells from lung (HMVEC-L) results in activation of a calcium-independent phospholipase A(2) (iPLA(2)), and this leads to arachidonic acid release and production of prostaglandin I(2) (PGI(2)) and platelet-activating factor (PAF). We stimulated lung endothelial cells isolated from iPLA(2)beta-knockout (KO) and wild type (WT) mice with thrombin and tryptase to determine the role of iPLA(2)beta in endothelial cell membrane phospholipid hydrolysis. Thrombin or tryptase stimulation of WT lung endothelial cells resulted in increased arachidonic acid release and production of PGI(2) and PAF. Arachidonic acid release and PGI(2) production by stimulated iPLA(2)beta-KO endothelial cells were significantly reduced compared to WT. Measured PLA(2) activity and PGI(2) production by iPLA(2)beta-KO cells were suppressed by pretreatment with (R)-bromoenol lactone (R-BEL), which is a selective inhibitor of iPLA2gamma. In contrast to the increase in PAF production induced by stimulation of WT endothelial cells, none was observed for KO cells, and this suggests that endothelial PAF production is entirely dependent on iPLA(2)beta activity. Because inflammatory cell recruitment involves the interaction of endothelial cell PAF with PAF receptors on circulating cells, these data suggest that iPLA(2)beta may be a suitable therapeutic target for the treatment of inflammatory lung diseases.

Asthma and atopy are associated with DEFB1 polymorphisms in Chinese children

Human beta-defensin (HBD)-1 is constitutively expressed in the airway, and hBD-1 plays crucial roles in innate immunity against respiratory pathogens. Asthma was associated with DEFB1 polymorphisms in Caucasians. This study investigates whether three single nucleotide polymorphisms (SNPs) in 5'-untranslated region of DEFB1 are associated with asthma phenotypes in Chinese children. Subjects aged 5-18 years were recruited from general pediatric clinics. Plasma IgE concentrations were measured by immunoassays. DEFB1 SNPs were characterized by restriction fragment length polymorphism. In all, 305 asthmatics and 156 controls were recruited. For asthma diagnosis, atopy and plasma total IgE, higher percentages of subjects with these outcomes had the minor alleles -20A and -52G (P = 0.041-0.0002). For log-transformed total IgE, the covariate was positive and significant for G-20A under recessive model (P = 0.001) and for G-52A under both recessive and codominant models (P = 0.008 and 0.035). The recessive model covariate was also positive and significant (P = 0.020) for C-44G on peripheral blood eosinophil count. The GCA haplotype of DEFB1 was significantly associated with asthma (odds ratio (95% confidence interval): 1.64 (1.05-2.57); P = 0.029). These results suggest that DEFB1 is a candidate gene for asthma and atopy in children.

Handle with care: targeting neutrophils in chronic obstructive pulmonary disease and severe asthma?

Neutrophils play an important role in the pathogenesis of airway inflammation in both chronic obstructive pulmonary disease (COPD) and severe asthma. Currently available drugs have only limited effects on neutrophilic airway inflammation, particularily in COPD. Therefore, great efforts are undertaken to address neutrophilic inflammation in chronic respiratory disorders, in particular COPD. This review summarizes the rationale for anti-neutrophilic treatment in COPD and asthma and gives a critical overview of current developments in drug therapy. Moreover, unanswered questions and limitations of clinical trial design and choice of outcome parameters for proof-of-concept studies with novel anti-neutrophilic drugs are discussed as well as potential safety issues.

LFA-1 (CD11a) as a therapeutic target

Leukocyte function associated antigen-1 (LFA-1) was one of the earliest of cell-surface molecules identified by monoclonal antibodies generated against leukocyte immunogens. This integrin heterodimer is perhaps best known as a classic adhesion molecule facilitating the interaction between T cells and antigen-presenting cells. However, varied studies indicate that LFA-1 has multi-faceted roles in the immune response including adhesion, activation and trafficking of leukocyte populations. While there has been long-standing interest in LFA-1 as a therapeutic target for regulating immunity, anti-LFA-1 therapy is still not a first-line indication for any clinical condition. Antagonism of LFA-1 with monoclonal antibodies, either alone or in combination with other agents, can result in regulatory tolerance in vivo. Furthermore, new generation humanized anti-LFA-1 monoclonal antibodies (Efalizumab) show at least modest promise for continued application in clinical trials. Thus, anti-LFA-1 forms a potential, but still largely unexploited, immunotherapy which may find its greatest application as an agent which augments other therapies.

Association of defensin beta-1 gene polymorphisms with asthma

BACKGROUND

Defensins are antimicrobial peptides that may take part in airway inflammation and hyperresponsiveness.

OBJECTIVE

We characterized the genetic diversity in the defensin beta-1 (DEFB1) locus and tested for an association between common genetic variants and asthma diagnosis.

METHODS

To identify single nucleotide polymorphisms (SNPs), we resequenced this gene in 23 self-defined European Americans and 24 African Americans. To test whether DEFB1 genetic variants are associated with asthma, we genotyped 4 haplotype-tag SNPs in 517 asthmatic and 519 control samples from the Nurses' Health Study (NHS) and performed a case-control association analysis. To replicate these findings, we evaluated the DEFB1 polymorphisms in a second cohort from the Childhood Asthma Management Program.

RESULTS

Within the NHS, single SNP testing suggested an association between asthma diagnosis and a 5' genomic SNP (g.-1816 T>C; P = .025) and intronic SNP (IVS+692 G>A; P = .054). A significant association between haplotype (Adenine, Cytosine, Thymine, Adenine [ACTA]) and asthma ( P = .024) was also identified. Associations between asthma diagnosis and both DEFB1 polymorphisms were observed in Childhood Asthma Management Program, a second cohort: g.-1816 T>C and IVS+692 G>A demonstrated significant transmission distortion ( P = .05 and .007, respectively). Transmission distortion was not observed in male subjects. The rare alleles (-1816C and +692A) were undertransmitted to offspring with asthma, suggesting a protective effect, contrary to the findings in the NHS cohort. Similar effects were evident at the haplotype level: ACTA was undertransmitted ( P = .04) and was more prominent in female subjects ( P = .007).

CONCLUSION

Variation in DEFB1 contributes to asthma diagnosis, with apparent gender-specific effects.

Serum ferritin elevation and acute lung injury in rats subjected to hemorrhage: reduction by mepacrine treatment

Ferritin regulates iron levels and, for unknown reasons, serum ferritin concentrations are increased in patients at risk for and with acute lung injury (ALI) and multiple organ failure. Uncomplexed iron could exacerbate the toxicity of the increased oxidative stress that occurs in patients with ALI and multiple organ failure and thereby contribute to disease. In the present investigation, the authors found that serum and lung lavage ferritin concentrations increased in hemorrhaged rats that develop ALI as manifested by increased lung inflammation (increased lung lavage leukocyte counts and lung myeloperoxidase activities) and increased lung leak (increased lung lavage protein concentrations). Treatment with mepacrine, a phospholipase A2 inhibitor, attenuated the increases in serum and lung lavage ferritin concentrations, lung inflammation, and lung leak that occur in rats subjected to hemorrhage. The findings show that serum and lung ferritin levels increase and may play a role in the development of acute lung injury caused by hemorrhage.

Lack of systemic oxidative stress during PAF challenge in mild asthma

To further establish the role of oxidative stress in the pathogenesis of acute bronchial asthma, we investigated the effects of platelet-activating factor (PAF) challenge on systemic oxidant-antioxidant balance in 12 asthmatic patients (age, 25+/-3[SEM] yr; FEV1, 95+/-10% predicted), using a double blinded, controlled with Lyso-PAF (L-PAF), cross-over design. Respiratory system resistance (Rrs), arterial blood gases, peripheral blood neutrophils and oxidant-antioxidant balance, including thiobarbituric acid (TBA)-malondialdehyde (MDA) adducts, protein sulphydryls and Trolox equivalent antioxidant capacity (TEAC), were assessed at baseline and 5, 15 and 45 min after PAF and L-PAF (18 microg each) bronchoprovocation. Urinary leukotriene E4 (uLTE4) elimination was measured 120 min after challenge. Compared with baseline, as expected, PAF increased significantly Rrs and AaPO2 and decreased PaO2 and peripheral blood neutrophils along with a rebound neutrophilia and increased uLTE4. By contrast, markers of systemic oxidative stress remained unaltered throughout the study. Unlike PAF, L-PAF-induced changes were negligible. We conclude that there is no systemic oxidant-antioxidant imbalance during acute bronchoconstriction induced by PAF in these patients with mild asthma.