Adverse effects of neutrophils on the lung

Antiplatelet Therapy for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a common and devastating syndrome that contributes to serious morbidities and mortality in critically ill patients. No known pharmacologic therapy is beneficial in the treatment of ARDS, and the only effective management is through a protective lung strategy. Platelets play a crucial role in the pathogenesis of ARDS, and antiplatelet therapy may be a potential medication for ARDS. In this review, we introduce the overall pathogenesis of ARDS, and then focus on platelet-related mechanisms underlying the development of ARDS, including platelet adhesion to the injured vessel wall, platelet-leukocyte-endothelium interactions, platelet-related lipid mediators, and neutrophil extracellular traps. We further summarize antiplatelet therapy, including aspirin, glycoprotein IIb/IIIa receptor antagonists, and P2Y12 inhibitors for ARDS in experimental and clinical studies and a meta-analysis. Novel aspirin-derived agents, aspirin-triggered lipoxin, and aspirin-triggered resolvin D1 are also described here. In this narrative review, we summarize the current knowledge of the role of platelets in the pathogenesis of ARDS, and the potential benefits of antiplatelet therapy for the prevention and treatment of ARDS.

Mitocryptides from Human Mitochondrial DNA-Encoded Proteins Activate Neutrophil Formyl Peptide Receptors: Receptor Preference and Signaling Properties

Phagocytic neutrophils express formyl peptide receptors (FPRs; FPR1 and FPR2) that distinctly recognize peptides starting with an N-formylated methionine (fMet). This is a hallmark of bacterial metabolism; similar to prokaryotes, the starting amino acid in synthesis of mitochondrial DNA-encoded proteins is an fMet. Mitochondrial cryptic peptides (mitocryptides; MCTs) with an N-terminal fMet could be identified by our innate immune system; however, in contrast to our knowledge about bacterial metabolites, very little is known about the recognition profiles of MCTs. In this study, we determined the neutrophil-recognition profiles and functional output of putative MCTs originating from the N termini of the 13 human mitochondrial DNA-encoded proteins. Six of the thirteen MCTs potently activated neutrophils with distinct FPR-recognition profiles: MCTs from ND3 and ND6 have a receptor preference for FPR1; MCTs from the proteins ND4, ND5, and cytochrome b prefer FPR2; and MCT-COX1 is a dual FPR1/FPR2 agonist. MCTs derived from ND2 and ND4L are very weak neutrophil activators, whereas MCTs from ND1, ATP6, ATP8, COX2, and COX3, do not exert agonistic or antagonistic FPR effects. In addition, the activating MCTs heterologously desensitized IL-8R but primed the response to the platelet-activating factor receptor agonist. More importantly, our data suggest that MCTs have biased signaling properties in favor of activation of the superoxide-generating NADPH oxidase or recruitment of β-arrestin. In summary, we identify several novel FPR-activating peptides with sequences present in the N termini of mitochondrial DNA-encoded proteins, and our data elucidate the molecular basis of neutrophil activation by MCTs.

The Influenza Virus Protein PB1-F2 Increases Viral Pathogenesis through Neutrophil Recruitment and NK Cells Inhibition

The influenza A virus (IAV) PB1-F2 protein is a virulence factor contributing to the pathogenesis observed during IAV infections in mammals. In this study, using a mouse model, we compared the host response associated with PB1-F2 with an early transcriptomic signature that was previously associated with neutrophils and consecutively fatal IAV infections. This allowed us to show that PB1-F2 is partly involved in neutrophil-related mechanisms leading to death. Using neutropenic mice, we confirmed that the harmful effect of PB1-F2 is due to an excessive inflammation mediated by an increased neutrophil mobilization. We identified the downstream effects of this PB1-F2-exacerbated neutrophil recruitment. PB1-F2 had no impact on the lymphocyte recruitment in the airways at day 8 pi. However, functional genomics analysis and flow cytometry in broncho-alveolar lavages at 4 days pi revealed that PB1-F2 induced a NK cells deficiency. Thus, our results identify PB1-F2 as an important immune disruptive factor during the IAV infection.

Drug-Induced Lung Toxicity

The number of blood-borne chemotherapeutic agents implicated in drug-induced lung toxicity continues to increase, although problems in detection remain. The initiation of drug-induced lung injury can have an immunologic or nonimmunologic basis. If endothelial cells are injured, interstitial pulmonary edema may result. Regardless of the source of injury, the progression of drug-induced lung toxicity is often quite similar, involving (1) parenchymal damage, (2) recruitment of inflammatory cells, and (3) progression of the inflammatory process. If the inflammatory reponse is sufficiently severe and disperse, increased collagen can be deposited in interstitial and intra-alveolar areas. The resulting attenuation of gas exchange can induce dyspnea and possibly death. Recent research suggests mediation of the fibrogenic process via cytokines such as transforming growth factor-β and tumor necrosis factor. Preliminary results demonstrating amelioration of cytokine mediated lung-induced fibrosis in animal models with appropriate antibodies suggest a possible future modality of therapy. Certain amphiphilic drugs are capable of eliciting a more specific form of lung toxicity. This class of drugs can interfere with phospholipid metabolism in pulmonary macrophages. In these cases, phospholipidosis results from phospholipid accumulation. The physiologic sequelae in human phospholipidosis is still uncertain.

The development of hyperbaric oxygen therapy for skin rejuvenation and treatment of photoaging

Hyperbaric oxygen therapy (HBOT), a therapy that have patients breath in pure oxygen in a pressurized chamber, has been long used as a treatment for conditions such as decompression sickness and carbon monoxide poisoning. Oxygen recently has been found to be an important component in skin rejuvenation, treatment of photoaging skin, and improvement in skin complexions. The interest in the use of HBOT for this purpose is continually growing and becoming more widespread. In addition to aging and genetic makeup, chronic UV radiation due to everyday exposure, especially UV-B, can greatly increase the rate of wrinkle formation through increasing skin angiogenesis and degradation of extracellular matrix molecules. The use of HBOT and hyperoxia conditions has been found to attenuate the formation of wrinkles from UV irradiation. It accomplishes the task by possibly inhibiting various processes and pathways involved such as the HIF1-α, VEGF, neutrophil infiltrations, and MMP-2 & MMP-9, which are directly involved with promoting skin angiogenesis in its active state. There are currently medical aesthetic clinics that are using oxygen therapy under high pressure applied directly to skin to reduce visible wrinkles but this procedure is not widespread yet due to more research that needs to be done on this topic. However, this treatment for wrinkles is definitely growing due to recent studies done showing the effectiveness of oxygen therapy on wrinkles. This review article will explore and summarize researches done on possible mechanisms dealing with the use of oxygen therapy for reduction of UVB-caused wrinkles, its side effects, and its possible future improvement and use in medicine.

Role of CXC chemokine receptor-2 in a murine model of bronchopulmonary dysplasia

The contribution of neutrophils and CXC chemokines to the pathogenesis of bronchopulmonary dysplasia is not well defined. The transgenic expression of IL-1β in the pulmonary epithelium causes lung inflammation and disrupts alveolar development in infant mice. To study the hypothesis that CXC chemokine receptor-2 (CXCR2) is a mediator of inflammatory lung injury, we compared lung development in IL-1β-expressing mice with wild-type (IL-1β/CXCR2(+/+)) or null (IL-1β/CXCR2(-/-)) CXCR2 loci. CXCR2 deficiency abolished the transmigration of neutrophils into the alveolar lumen in IL-1β-expressing mice, but did not alter the number of neutrophils in the parenchyma. The deletion of CXCR2 increased the alveolar chord length and reduced the survival of mice when IL-1β was expressed from the pseudoglandular to the alveolar stages. The capillary configuration was highly abnormal in both IL-1β/CXCR2(+/+) and IL-1β/CXCR2(-/-) lungs, but in very different ways. The cellular area of the parenchyma and the total capillary area of IL-1β/CXCR2(+/+) and IL-1β/CXCR2(-/-) mice were smaller than those of control/CXCR2(+/+) and control/CXCR2(-/-) mice, but the ratio of capillary area to cellular area was similar in all four genotypes. When IL-1β was expressed during the saccular stage, IL-1β/CXCR2(-/-) mice had smaller alveolar chord lengths and better survival than did IL-1β/CXCR2(+/+) mice. Independent of the timing of IL-1β expression, IL-1β increased alveolar septal thickness in mice with wild-type CXCR2 loci, but not in CXCR2 null mice. Depending on the developmental stage at the time of the inflammatory insult, inhibition of the CXCR2 pathway may exert opposite effects on alveolar septation in the neonatal lung.

Is tissue engineering and biomaterials the future for lower urinary tract dysfunction (LUTD)/pelvic organ prolapse (POP)?

The fields of tissue engineering and regenerative medicine have seen major advances over the span of the past two decades, with biomaterials playing a central role. Although the term "regenerative medicine" has been applied to encompass most fields of medicine, in fact urology has been one of the most progressive. Many urological applications have been investigated over the past decades, with the culmination of these technologies in the introduction of the first laboratory-produced organ to be placed in a human body.1 With the quality of life issues associated with urinary incontinence, there is a strong driver to identify and introduce new technologies and the potential exists for further major advancements from regenerative medicine approaches using biomaterials, cells or a combination of both. A central question is why use biomaterials? The answer rests on the need to make up for inadequate or lack of autologous tissue, to decrease morbidity and to improve long-term efficacy. Thus, the ideal biomaterial needs to meet the following criteria: (1) Provide mechanical and structural support, (2) Maintain compliance and be biocompatible with surrounding tissues, and (3) Be "fit for purpose" by meeting specific application needs ranging from static support to bioactive cell signaling. In essence, this represents a wide range of biomaterials with a spectrum of potential applications, from use as a supportive or bulking implant alone, to implanted biomaterials that promote integration and eventual replacement by infiltrating host cells, or scaffolds pre-seeded with cells prior to implant. In this review we shall discuss the structural versus the integrative uses of biomaterials by referring to two key areas in urology of (1) pelvic organ support for prolapse and stress urinary incontinence, and (2) bladder replacement/augmentation.

The pathogenesis of photoaging: the role of neutrophils and neutrophil-derived enzymes

The hallmark of photoaged skin is solar elastosis, which is probably an end product of elastic fiber degradation. Exposure of human skin to a certain threshold of UV, infrared radiation (IR), and heat leads to an influx of neutrophils. These neutrophils are packed with potent proteolytic enzymes capable of degrading collagen and, particularly, elastic fibers. Neutrophil-derived proteolytic enzymes are held responsible for the extracellular matrix (ECM) damage observed in several non-dermatological conditions. Furthermore, neutrophil elastase, a major product of neutrophils, is strongly associated with solar elastosis in mice. Taken together with our data that show in vivo proteolytic activity of neutrophil-derived elastase and matrix metalloproteinases (MMPs) in UV-exposed skin, we have hypothesized earlier that neutrophils are major contributors to the photoaging process. Although several groups have shown that MMPs are also induced in skin exposed to relatively low doses of UV, IR, and heat, clinical data indicate that high(er) doses of UV, IR, and heat are necessary to induce photoaging or photoaging-like pathology in the skin. Therefore, we propose that MMPs generated by suberythemogenic doses of UV and low doses of IR/heat are involved in cellular processes other than ECM degradation.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 67-72; doi:10.1038/jidsymp.2009.15.

Ghrelin treatment suppresses neutrophil-dominant inflammation in airways of patients with chronic respiratory infection

BACKGROUND

Persistent neutrophil influx into the airways is a characteristic of chronic respiratory infection and contributes to the deterioration of pulmonary function. Ghrelin is a novel growth hormone (GH)-releasing peptide with potential anti-inflammatory activities. The present study investigated whether or not ghrelin can reduce neutrophil-dominant inflammation in airways of patients with chronic respiratory infection.

POPULATIONS AND METHODS

Synthesized ghrelin was administered intravenously for 3 weeks to 7 cachectic patients with chronic respiratory infection to confirm ghrelin's effects on airway inflammation and nutrition state. Neutrophils, neutrophil products and inflammatory cytokines in sputum were used as markers of airway inflammation. Changes in serum protein levels were also evaluated along with plasma catecholamine levels. Exercise tolerance was assessed by measuring 6-min walking distance before and after 3 weeks of ghrelin treatment.

RESULTS

Three-week ghrelin administration decreased neutrophil density and inflammatory cytokine levels in sputum, reduced plasma norepinephrine level, and increased body weight, serum protein level, and 6-min walking distance.

CONCLUSIONS

Ghrelin administration suppressed airway inflammation by decreasing neutrophil accumulation in lungs and increased body weight. These findings may contribute to the development of supportive therapies for patients with refractory chronic respiratory infection.

Proteomic analysis of proteins from bronchoalveolar lavage fluid reveals the action mechanism of ultrafine carbon black-induced lung injury in mice

Previous studies have shown that ultrafine carbon black (ufCB) could cause oxidative stress and lung injury, but the mechanisms have not been clearly demonstrated. In this study, 1-D gel electrophoresis coupled with LC/MS/MS (1-D geLC/MS/MS) was carried out with bronchoalveolar lavage fluid (BALF) to identify proteins associated with ufCB-induced lung injury. If required, Western blot was conducted additionally to validate proteins. Thirty-three proteins were identified, including leukemia inhibitory factor receptor (LIFR) and epidermal growth factor receptor (EGFR). Western blot analysis showed that ufCB exposure caused the increases of LIFR and EGFR in BALF and decreases of both receptors in lung tissues, suggesting the acceleration of epithelial shedding from the lung and increase of cell debris with membrane proteins EGFR and LIFR in BALF. There were strong correlations between vascular endothelial growth factor (VEGF) and albumin (p<0.01) or alpha2-macroglobulin (alpha2M) in BALF (p<0.05). Importantly, antioxidant ceruloplasmin (Cp) was shown to be produced from lung epithelial cells in response to ufCB exposure. This is the first study to apply 1-D ge LC/MS/MS and experimental studies to reveal the mechanisms involved in the pathogenesis of ufCB-induced lung injury.

Anti-KC autoantibody:KC complexes cause severe lung inflammation in mice via IgG receptors

We have shown previously that high concentrations of IL-8 associated with anti-IL-8 autoantibodies (anti-IL-8:IL-8 complexes) are present in lung fluids from patients with the acute respiratory distress syndrome (ARDS), and correlate both with the development and outcome of ARDS. We also detected deposition of these complexes in lung tissues from patients with ARDS but not in control tissues. Moreover, we determined that IgG receptors (FcgammaRs) mediate activity of anti-IL-8:IL-8 complexes. In the current study, we generated anti-KC (KC = chemokine (CXC motif) ligand 1 (CXCL1)) autoantibody:KC immune complexes (KC-functional IL-8) in lungs of mice to develop a mouse model of autoimmune complex-induced lung inflammation. Both wild-type (WT) and gamma-chain-deficient mice that lack receptors for immune complexes (FcgammaRs) were studied. First, the mice were immunized with KC to induce anti-KC autoantibodies. Then, KC was administered intratracheally to generate anti-KC:KC complexes in the lung. Presence of anti-KC:KC complexes was associated with development of severe pulmonary inflammation that was, however, dramatically suppressed in gamma-chain-deficient mice. Second, because sepsis is considered the major risk factor for development of ARDS, we evaluated LPS-treated WT as well as gamma-chain-deficient mice for the presence of anti-KC:KC complexes and pulmonary inflammatory responses. We detected complexes between anti-KC autoantibodies and KC in lung lavages and tissues of mice treated with LPS. Moreover, gamma-chain-deficient mice that lack receptors for immune complexes were protected from LPS-induced pulmonary inflammation. Our results suggest that immune complexes containing autoantibodies contribute to development of lung inflammation in LPS-treated mice.

Anti-interleukin 8 autoantibody:interleukin 8 immune complexes visualized by laser confocal microscopy in injured lung

CONTEXT

Anti-interleukin 8 autoantibody:interleukin 8 (anti-IL-8 autoantibody:IL-8) complexes are present in lung fluids of patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and levels of these complexes correlate with progression to and the outcome of ARDS. Fc gammaRIIa, an immunoglobulin G (IgG) receptor, mediates proinflammatory activity of the complexes.

OBJECTIVE

To evaluate lung tissues from patients with ARDS for presence of anti-IL-8 autoantibody:IL-8 complexes and to establish whether the complexes associate with Fc gammaRIIa.

DESIGN

Lung tissue sections from 3 patients with ARDS and sections of normal lung tissues from 3 patients were stained with antibodies against IL-8 and IgG to detect immune complexes and with antibody against Fc gammaRIIa. In some experiments, sections were blocked with anti-Fc gamma RIIa antibody before staining. Samples were analyzed using confocal microscopy.

RESULTS

Interleukin 8 costained with IgG and Fc gammaRIIa in lung tissues from patients with ARDS but not in control tissues, suggesting that anti-IL-8 autoantibody:IL-8 complexes are deposited in lungs of patients with ARDS via Fc gammaRIIa. Further, colocalization between IL-8 and Fc gammaRIIa could be blocked by anti-Fc gammaRIIa.

CONCLUSIONS

Our data demonstrate that anti-IL-8 autoantibody:IL-8 complexes are present in lung tissues of patients with ARDS, and are attached to Fc gammaRIIa.

Protein kinase C inhibition attenuates hypochlorite-induced acute lung injury

Neutrophil-derived oxidative stress plays a crucial role in acute lung injury. Hypochlorite/hypochlorous acid (HOCl) is a major oxidant of neutrophils. Protein kinase C (PKC) may be an appropriate target for HOCl due to its functionally important thiols. This study investigates the role of PKC in HOCl-induced acute lung injury. Isolated lung preparations were from 30 rabbits. HOCl (1000 nmol min(-1)) or buffer (control) were infused into isolated rabbit lungs. Pulmonary artery pressure (PAP [Torr]) and lung weight were continuously measured. Capillary filtration coefficient (K(f,c)), was measured at baseline and at 30, 60, 90 min. Experiments were terminated at 105 min or when fluid retention exceeded 50 g. The non-selective protein kinase inhibitor staurosporin (100 nM) or the selective PKC inhibitor bisindolylmaleimide I (GF109203X, 10nM) were added to the perfusate 5 min prior to the start of the experiments. Staurosporin completely prevented the HOCl-induced increase in PAP (no change versus DeltaPAP(max) 5.2+/-0.78) but did not influence the increase in vascular permeability. GF109203X delayed the HOCl-induced increase in PAP and vascular permeability. PAP(max) was observed significantly later in the HOCl-GF109203X group (84.4+/-4.0 min) in comparison with the HOCl group (52.1+/-3.5 min). Termination of the experiments due to edema formation occurred significantly later in experiments with GF109203X (91.8+/-1.9 versus 79.2+/-4.1 min). Protein kinases are involved in HOCl-induced acute lung injury. Specifically PKC inhibition delayed HOCl-induced increases in PAP and vascular permeability.

Should patients with acute exacerbation of chronic bronchitis be treated with antibiotics? Advantages of the use of fluoroquinolones

The pathological changes in chronic bronchitis (CB) produce airflow obstruction, reduce the effectiveness of the mucocilliary drainage system and lead to bacterial colonisation of bronchial secretion. The presence of bacteria induces an inflammatory response mediated by leukocytes. There is a direct relationship between the degree of impairment of the mucocilliary drainage system, the density of bacteria in mucus and the number of leukocytes in the sputum. Purulent sputum is a good marker of a high bacterial load. Eventually, if the number of leukocytes is high, their normal activity could decrease the effectiveness of the drainage system, increase the bronchial obstruction and probably damage the lung parenchyma. Whenever the density of bacteria in the bronchial lumen is >or=10(6) CFU/mL, there is a high probability that the degree of inflammatory response will lead to a vicious cycle which in turn tends to sustain the process. This situation can arise during the clinical course of any acute exacerbation of CB, independently of its aetiology, provided the episode is sufficiently severe and/or prolonged. Fluoroquinolones of the third and fourth generation are bactericidal against most microorganisms usually related to acute exacerbations of CB. Their diffusion to bronchial mucus is adequate. When used in short (5-day) treatment they reduce the bacterial load in a higher proportion than is achieved by beta-lactam or macrolide antibiotics given orally. Although the clinical cure rate is similar to that obtained with other antibiotics, the time between exacerbations could be increased.

The oxidants hypochlorite and hydrogen peroxide induce distinct patterns of acute lung injury

Oxidative stress due to activated neutrophils, macrophages and endothelial cells plays a crucial role in acute lung injury. This study compares the effects of the nonradical oxidants hypochlorite (HOCl) and hydrogen peroxide (H2O2) on pulmonary artery pressure [PAPtorr], capillary filtration coefficient (Kf,c), tissue lipid peroxidation (LPO) and reduced glutathione (GSH) depletion. HOCl, H2O2 (1000 nmol min(-1)) or buffer (control) is infused into isolated rabbit lungs. PAP, K(f,c) and lung weight were measured. Experiments were terminated after 105 min or when fluid retention exceeded 50 g. Lung tissue was analyzed for LPO products and GSH. The oxidants induced comparable maximum effects. However, the patterns of lung injury were distinct: H2O2 infusion evoked an early biphasic pressure response (DeltaPAPmax 2.8+/-0.22/4.2+/-0.37 after 5.7+/-1.4/39+/-4.0 min) and a sixfold increase in Kf,c after 90 min. HOCl application caused a late pressure response (DeltaPAPmax 7.6+/-1.7 after 50.6+/-3.7 min) and a sevenfold increase in Kf,c after 60 min. H2O2-induced effects were attenuated by desferal. This may suggest an involvement of transition metal catalysed hydroxyl radical formation. Different oxidants induced distinct patterns of changes in PAP and Kf,c , which are accompanied by a comparable accumulation of LPO products and by a distinct degree of GSH depletion.

Divergent effects of alpha1-antitrypsin on neutrophil activation, in vitro

alpha1-Antitrypsin (AAT) is a major circulating serine proteinase inhibitor in humans. The anti-proteinase activity of AAT is inhibited by chemical modification. These include inter- or intramolecular polymerisation, oxidation, complex formation with target proteinases (e.g., neutrophil elastase), and/or cleavage by multi-specific proteinases. In vivo, several modified forms of AAT have been identified which stimulate biological activity in vitro unrelated to inhibition of serine proteinases. In this study we have examined the effects of native and polymerised AAT and C-36 peptide, a proteolytic cleavage product of AAT, on human neutrophil activation, in vitro. We show that the C-36 peptide displays striking concentration-dependent pro-inflammatory effects on human neutrophils, including induction of neutrophil chemotaxis, adhesion, degranulation, and superoxide generation. In contrast to C-36 peptide, native and polymerised AAT at similar and higher concentrations showed no effects on neutrophil activation. These results suggest that cleavage of AAT may not only abolish its proteinase inhibitor activity, but can also generate a powerful pro-inflammatory activator for human neutrophils.

Continuous subcutaneous injection reduces polymorphonuclear leukocyte activation by granulocyte colony-stimulating factor

The use of granulocyte colony stimulating factor (G-CSF) for recovery from neutropenia has been established; however, acute lung injury due to G-CSF-induced polymorphonuclear leukocyte (PMN) activation is a serious complication. This study was designed to compare the activation of PMN with single bolus administration and continuous administration of G-CSF. Healthy volunteers (age 33.8 ± 1.4 yr; n = 6) received a single bolus injection of 50 μm/m2of G-CSF (SI; n = 6) or continuous subcutaneous injection of 50 μm/m2of G-CSF for 24 h (CI; n = 6) and were followed for 48 h. Circulating leukocyte counts, markers of activation on PMN, and circulating levels of G-CSF, IL-6, and PMN elastase were measured. SI rapidly increased serum G-CSF levels, which peaked at 4 h, whereas CI gradually increased G-CSF levels, which remained at a steady level from 8 to 24 h. SI caused a rapid decrease in PMN counts at 0.5 h followed by sustained increase to peak at 12 h. CI gradually increased PMN counts, which peaked at 24 h, but the peak values were not significantly different between the groups. SI-induced activation of PMN, which was characterized by increased expression of CD11b, decreased expression of L-selectin, and increased F-actin content, led to increases in serum IL-6 and PMN elastase level. Such changes were all attenuated with CI ( P < 0.05). We conclude that continuous subcutaneous injection of G-CSF resulted in a marrow response similar to that to a single injection but yielded reduced PMN activation.

Proteases and lung injury

OBJECTIVE

Acute respiratory distress syndrome (ARDS) represents an inflammatory process that is initiated by diverse systemic and/or pulmonary insults, resulting in a clinical syndrome of severe respiratory distress and refractory hypoxemia. Neutrophils and their cytotoxic products, including oxidants and proteases, such as elastase, have been implicated as playing a key role in the pathophysiology of ARDS. This article reviews some of the physiologic actions of proteases, specifically elastase, the evidence for neutrophil elastase involvement in ARDS, and the potential therapeutic use of neutrophil elastase inhibitors in lung injury.

DATA SOURCE

A review of published literature (original articles and reviews) in English from 1965 to 2002.

CONCLUSION

Although the data support a key role for neutrophil elastase in the pathogenesis of ARDS, further study is needed to fully define the actions of neutrophil elastase, and how these actions affect host functions, before we can exploit this knowledge for therapeutic benefit.

High in comparison with low tidal volume ventilation aggravates oxidative stress-induced lung injury

Ventilator settings influence the development and outcome of acute lung injury. This study investigates the influence of low versus high tidal volume (V(t)) on oxidative stress-induced lung injury. Isolated rabbit lungs were subjected to one of three ventilation patterns (V(t)-positive end-expiratory pressure, PEEP): LVZP (6 ml/kg-0 cm H(2)O), HVZP (12 ml/kg-0 cm H(2)O), LV5P (6 ml/kg-5 cm H(2)O). These ventilation patterns allowed a comparison between low and high V(t) without dependence on peak inspiratory pressure (PIP). Infusion of hypochlorite (1000 nmol/min) or buffer (control) was started at t=0 min. Pulmonary artery pressure (PAP), PIP and weight were continuously recorded. Capillary filtration coefficient [K(f,c) (10(-4) ml s(-1) cm H(2)O(-1) g(-1))] was gravimetrically determined (-15/30/60/90/120 min).PIP averaged 5.8+/-0.6/13.9+/-0.6/13.9+/-0.4 cm H(2)O in the LVZP, HVZP and LV5P groups. PIP, K(f,c) or PAP did not change in control groups, indicating that none of the ventilation patterns caused lung injury by themselves. Hypochlorite-induced increase in K(f,c) but not hypochlorite-induced increase in PAP, was significantly attenuated in the LVZP-/LV5P- versus the HVZP-group (K(f,c,max.) 1.0+/-0.23/1.4+/-0.40 versus 3.2+/-1.0*). Experiments with hypochlorite were terminated due to excessive edema (>50 g) at 97+/-2.2/94.5+/-4.5 min in the LVZP-/LV5P-group versus 82+/-3.8* min in the HVZP-group (*: P<0.05). Low V(t) attenuated oxidative stress-induced increase in vascular permeability independently from PIP and PEEP.

Pathogenesis of pneumococcal pneumonia in cyclophosphamide-induced leukopenia in mice

Streptococcus pneumoniae pneumonia frequently occurs in leukopenic hosts, and most patients subsequently develop lung injury and septicemia. However, few correlations have been made so far between microbial growth, inflammation, and histopathology of pneumonia in specific leukopenic states. In the present study, the pathogenesis of pneumococcal pneumonia was investigated in mice rendered leukopenic by the immunosuppressor antineoplastic drug cyclophosphamide. Compared to the immunocompetent state, cyclophosphamide-induced leukopenia did not hamper interleukin-1 (IL-1), IL-6, macrophage inflammatory protein-1 (MIP-1), MIP-2, and monocyte chemotactic protein-1 secretion in infected lungs. Leukopenia did not facilitate bacterial dissemination into the bloodstream despite enhanced bacterial proliferation into lung tissues. Pulmonary capillary permeability and edema as well as lung injury were enhanced in leukopenic mice despite the absence of neutrophilic and monocytic infiltration into their lungs, suggesting an important role for bacterial virulence factors and making obvious the fact that neutrophils are ultimately not required for lung injury in this model. Scanning and transmission electron microscopy revealed extensive disruption of alveolar epithelium and a defect in surfactant production, which were associated with alveolar collapse, hemorrhage, and fibrin deposits in alveoli. These results contrast with those observed in immunocompetent animals and indicate that leukopenic hosts suffering from pneumococcal pneumonia are at a higher risk of developing diffuse alveolar damage.

Tissue lipid peroxidation and reduced glutathione depletion in hypochlorite-induced lung injury

STUDY OBJECTIVE

Neutrophils are involved in acute lung injury during ARDS via several mechanisms. This study focuses on neutrophil-derived oxidative stress. Hypochlorite is a major neutrophil-derived oxidant. This study characterizes hypochlorite-induced acute changes in pulmonary circulation and the involvement of tissue lipid peroxidation (LPO) and reduced glutathione (rGSH) depletion.

METHODS

Hypochlorite (500, 1,000, and 2,000 nmol/min) or buffer (control) were infused into isolated rabbit lungs. Pulmonary artery pressure (PAP), capillary filtration coefficient (Kf,c) [10(4)/mL/s/cm H(2)O/g], and lung weight were measured. Experiments were terminated after 105 min or when fluid retention was > 50 g. Lung tissue was frozen immediately after termination of the experiments and analyzed for LPO products and rGSH (nanomoles per milligram of protein).

RESULTS

Baseline PAP and Kf,c values averaged from 6.1 to 6.5 mm Hg and from 0.97 to 1.23, respectively, in all groups. Hypochlorite infusion of 500, 1,000, and 2,000 nmol/min (n = 5 to 7 per group) evoked an increase (mean +/- SEM) in maximum PAP (PAPmax) [12.9 +/- 2.1, 14.3 +/- 1.7, and 13.3 +/- 2.2 mm Hg], in maximum Kf,c (Kf,cmax) [1.9 +/- 1.2, 6.34 +/- 1.2, and >10.0], and in tissue LPO products (1.7 +/- 0.06, 2.1 +/- 0.06, and 2.3 +/- 0.11 vs 1.4 +/- 0.04 in controls), and a decrease in tissue rGSH (73.4 +/- 8.7, 43.0 +/- 9.6, and 50.4 +/- 7.2 vs 139 +/- 12.6 in controls). Parameters of lung injury (PAPmax and Kf,cmax) of each single experiment were closely correlated with tissue rGSH but did not correlate with tissue LPO products. All changes are significant (p < 0.05) vs control.

CONCLUSION

The neutrophil-specific oxidant hypochlorite induces acute lung injury, rGSH depletion, and LPO in isolated rabbit lungs. The lung injury correlates with rGSH depletion, suggesting an important mechanistic role in hypochlorite-induced acute lung injury.

Isolation and properties of stachyrase A, a chymotrypsin-like serine proteinase from Stachybotrys chartarum

A strain of the common mold Stachybotrys chartarum has been isolated from the lung of a child with pulmonary hemorrhage. We report the purification of stachyrase A, a new serine chymotrypsin-like proteinase from S. chartarum. This enzyme cleaves major protease inhibitors, several biologically active peptides, and collagen, all of which are found in the lung.

Treatment of periodontitis by local administration of minocycline microspheres: a controlled trial

BACKGROUND

Periodontitis is an inflammatory condition of tooth-supporting tissues that is usually treated by mechanical removal of plaque and microorganisms that adhere to teeth. This treatment, known as scaling and root planing, is not optimally effective. Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes such as probing depth reduction. This article reports on the efficacy and safety of locally administered microencapsulated minocycline.

METHODS

Seven hundred forty-eight (748) patients with moderate to advanced periodontitis were enrolled in a multi-center trial and randomized to 1 of 3 treatment arms: 1) scaling and root planing (SRP) alone; 2) SRP plus vehicle; or 3) SRP plus minocycline microspheres. The primary outcome measure was probing depth reduction at 9 months. Clinical assessments were performed at baseline and 1, 3, 6, and 9 months.

RESULTS

Minocycline microspheres plus scaling and root planing provided substantially more probing depth reduction than either SRP alone or SRP plus vehicle. The difference reached statistical significance after the first month and was maintained throughout the trial. The improved outcome was observed to be independent of patients' smoking status, age, gender, or baseline disease level. There was no difference in the incidence of adverse effects among treatment groups.

CONCLUSIONS

Scaling and root planing plus minocycline microspheres is more effective than scaling and root planing alone in reducing probing depths in periodontitis patients.

Influence of cyclooxygenase and lipoxygenase inhibitors on oxidative stress-induced lung injury

OBJECTIVE

Hypochlorous acid (HOCl) is the main oxidant of activated neutrophil granulocytes. It is generated by their myeloperoxidase during respiratory burst. This study investigates the effects of HOCl on vascular permeability and pulmonary artery pressure (PAP) and characterizes the influence of the cyclooxygenase inhibitor acetylsalicylic acid (ASA) and the 5-lipoxygenase inhibitor caffeic acid (CaA) on the observed alterations.

DESIGN

Prospective experimental study using isolated perfused rabbit lungs.

SETTING

Experimental laboratory in a university teaching hospital.

INTERVENTIONS

HOCl was infused into the perfusate containing either no inhibitors, ASA (500 micromol/L), or CaA (1 micromol/L).

MEASUREMENTS AND MAIN RESULTS

PAP, pulmonary venous pressure, and ventilation pressure as well as lung weight gain were continuously recorded. Capillary filtration coefficient [Kf,c (10(-4) cm3 x sec(-1) x cm H2O(-1) x g(-1)]) was calculated before and 30, 60, and 90 mins after start of HOCl application. Continuous HOCl application (500, 1000, and 2000 nmol/min) resulted in a time- and dose-dependent increase in Kf,c and PAP with a threshold dose at 500 nmol/min. The onset of these changes was inversely related to the HOCl dose used. Both inhibitors, CaA and ASA, exhibited protective effects on the HOCl-induced alterations in pulmonary microcirculation. ASA predominantly reduced the HOCl-induced pressure response and had a minor but also significant inhibitory effect on edema formation as measured by Kf,c and fluid retention. CaA reduced significantly the rise in Kf,c and subsequent edema formation without effects on pulmonary pressure response.

CONCLUSIONS

Cyclooxygenase and 5-lipoxygenase are involved in oxidative stress induced acute lung injury, suggesting a link between neutrophil-derived oxidative stress and endothelial eicosanoid metabolism.

A critical approach to noncardiac chest pain: pathophysiology, diagnosis, and treatment

Approximately 30% of coronary angiograms performed in this country are negative for significant coronary artery disease. These patients are classified as having noncardiac or unexplained chest pain (UCP). Despite the good overall prognosis, this condition has significant morbidity and costs. The pathophysiology of this condition is likely caused by overlapping cardiac, esophageal, and psychiatric abnormalities with visceral hyperalgesia playing a central role. Gastroenterologists are often consulted in the evaluation of these patients because esophageal disorders are among the most common conditions associated with UCP. However, clinical symptoms are unreliable in differentiating between esophageal and cardiac causes of UCP. Gastroesophageal reflux disease, not esophageal motility disorders, is the most common esophageal disorder present in patients with UCP. The most useful diagnostic test in the evaluation of UCP is 24-h pH monitoring. An initial empiric trial of high-dose acid suppression is the most cost-effective intervention in the management of these patients. A clinical algorithm is suggested for the evaluation and treatment of UCP.

Neutrophil recruitment and increased permeability during acute lung injury induced by lipopolysaccharide

The intranasal administration of lipopolysaccharide (LPS) to mice triggers a huge influx of polymorphonuclear neutrophils (PMNs) into the airway spaces, with a peak at 48 h. The increase in protein concentration, an index of microvascular permeability, displayed a different pattern, i.e., a first increase with a plateau between 3 and 24 h followed by a second increase peaking at 72 h. When mice were depleted of circulating PMNs, the increase in protein concentration was inhibited at 3 h but not at 24 h. The lack of PMN involvement at 24 h was confirmed by 1) in situ activation of exudated PMNs present in the air spaces on intranasal administration of LPS and 2) induction of the migration of PMNs sequestered in lung vessels on intraperitoneal administration of LPS. These findings show that the increase in microvascular permeability during lung inflammation is due to at least two distinct mechanisms, an early one related to the neutrophil influx and a delayed one occurring even under neutropenic conditions.

Intraesophageal acid perfusion sensitizes the esophagus to mechanical distension: a Barostat study

OBJECTIVE

The pathogenesis of noncardiac chest pain is unclear. Increased gastroesophageal reflux and decreased pain thresholds to intraesophageal balloon distension have been demonstrated in a proportion of such patients. We aimed to investigate whether acid exposure sensitizes esophageal mechanoreceptors in healthy volunteers.

METHODS

After an overnight fast, an infinitely compliant balloon, 4.5 cm in length and mounted on a multilumen transnasal manometry catheter, was placed 8.5 cm above the lower esophageal sphincter in 12 healthy male volunteers aged 18-39 yr. After determination of the minimal distending pressure, the balloon was inflated up to 48 mm Hg by means of a computer-controlled barostat (G & J Electronics, Canada). Graded stepwise distensions were interspersed with random decreases in pressure to two-thirds of the previous value. At each pressure level, the subjects were asked to report on sensation and the presence of pain. Baseline distension was repeated to determine reproducibility of the pressure/volume relationship and also the perception and pain thresholds. After the baseline distension sequence, the esophagus was perfused for 20 min (at 7 ml/min) with either normal saline (control) or 0.1 N hydrochloric acid at 37 degrees C on a random basis.

RESULTS

Basal sensory thresholds varied widely (first perception 5-36 mm Hg, pain 8 > or = 43 mm Hg). Two subjects did not experience pain up to the maximum distending pressure (42 and 43 mm Hg, respectively, after correction for the minimal distending pressure). Esophageal body compliance was similar on repeat distension. Sensory thresholds were reproducible with different distensions (perception r = 0.99, pain r = 0.95). Saline resulted in no significant changes in perception or pain thresholds. Acid perfusion reduced first perception (median before and after acid, 15 mm Hg and 8 mm Hg, respectively, p = 0.05) and pain threshold (median before and after acid, 32.5 mm Hg and 26.5 mm Hg, respectively, p = 0.05). When compared to changes after saline perfusion, acid perfusion reduced the perception threshold (median change, -3.8 mm Hg vs 0 mm Hg, p = 0.04) and tended to reduce the pain threshold (median change, -3.75 mm Hg vs +0.75 mm Hg, p = 0.09).

CONCLUSIONS

Intraesophageal balloon distension using a barostat is a reproducible method of measuring esophageal body compliance and sensory thresholds. Acute exposure to acid seems to sensitize the esophagus to perception from intraluminal balloon distension.

Does programmed cell death (apoptosis) play a role in the development of multiple organ dysfunction in critically ill patients? a review and a theoretical framework

OBJECTIVES

To critically review the current understanding of the pathophysiologic events leading to the development of secondary multiple organ dysfunction (MODS) in critical illness and to examine the role of apoptosis (programmed cell death) as a mechanism involved in the progression of MODS.

DATA SOURCES

Research and review articles published since 1982 on the pathophysiology of MODS, particularly the role of cytokines, reactive oxygen species, heat shock proteins, and apoptosis. Research and review articles on the physiology of apoptosis. Articles include human/animal and in vitro/in vivo studies.

DATA EXTRACTION

The most prevalent mediating factors of MODS were examined for their potential to induce apoptosis, as reported in the literature. The combination of several of the above factors was also examined in terms of apoptosis-triggering potential.

DATA SYNTHESIS

Specific pathophysiologic conditions related to the onset of MODS have been shown to affect apoptotic rates in organ tissue cells and their respective endothelial cells in animal and in vitro models. These conditions include the following: a) increased release of inflammation-related cytokines; b) increased production of oxygen free radicals associated with ischemia/reperfusion injury and states of low tissue perfusion; c) expression and release of heat shock proteins from tissue cells and the liver; d) elevated glucocorticoid concentrations after adrenal cortex activation; and e) release of bacterial products into the systemic circulation.

CONCLUSION

The most important MODS-related pathophysiologic conditions known to date have been shown to affect programmed cell death rates in almost all cell types. Organ-specific cell death involving both parenchymal and microvasculature endothelial cells is conceivably underlying organ dysfunction. The hypothesis that increased apoptotic rates are involved in organ dysfunction may provide a unifying theory for the pathophysiology of MODS.

In vitro influence of parenteral lipid emulsions on the respiratory burst of neutrophils

The in vitro effect of a fish oil-derived lipid emulsion (omega-3) on the superoxide anion production during the respiratory burst (RB) of human neutrophils was compared to a LCT lipid (Intralipid), and an LCT/MCT emulsion (Lipofundin MCT). The effects of two concentrations (60 and 600 micrograms/mL) were evaluated by rhodamine in a flow cytometer. The RB was induced either by stimulation with Escherichia coli (E. coli) or by priming with TNF-alpha and FMLP stimulation. The results (mean +/- SD%, P < 0.05) were compared to positive control responses (RB without lipids). omega-3 (60 micrograms/mL, -8.2 [9.3]%; 600 micrograms/mL, -9.6 [11.1]%) and LCT (600 micrograms/mL, -8.0 [9.3]%) significantly suppressed the RB after stimulation with E. coli. LCT/MCT increased the RB after E. coli (60 micrograms/mL, 15.7 [15.4]%; 600 micrograms/mL, 42.7 [21.4]%) as well as after TNF-alpha/FMLP stimulation (600 micrograms/mL, 27.4 [23.7]%). The in vitro influence of parenteral lipid emulsions on the superoxide anion production of human neutrophils is dependent on the length of the fatty acid molecule.

Inhibition of PMN- and HOC1-induced vascular injury in isolated rabbit lungs by acetylsalicylic acid: a possible link between neutrophil-derived oxidative stress and eicosanoid metabolism?

Neutrophils are involved in the pathogenesis of acute lung injury. The neutrophil-derived enzyme myeloperoxidase (MPO) catalyzes the formation of the oxidant hypochlorous acid (HOCl). This study characterizes the effects of (A) continuous HOCl infusion, and (B) stimulated neutrophils on pulmonary circulation in an isolated rabbit lung model. Furthermore, the effect of cyclooxygenase inhibition by acetylsalicylic acid (ASA, 0.5 mM) on these effects was investigated. (A) Infusion of HOCl (in nmol min-1, groups: 0, 0+ASA, 1000, 1000+ASA, 2000, and 2000+ASA) into the isolated organ was started after a 45-min steady-state period (t=0). (B) Neutrophils (PMN group: 1480+/-323 and ASA group 1294+/-320 microliter-1) were added into the perfusate between (t=-45 min) and stimulated with FMLP (1 microM) after two 45-min steady-state periods (t=0). Perfusate MPO activity was measured at t=-90, -45, 0, 1, 2, 3, 5, 10, 15, 30, 60, and 90 min. For both groups, pulmonary artery pressure (PAP) and lung weight were continuously recorded and the capillary filtration coefficient (Kf,c in 10(-4) cm(3) s(-1) cm H2O(-1) g(-1) was calculated from the slope of weight gain after a hydrostatic challenge at t=-45, -15, 30, 60 and 90 min. (A) Continuous HOCl infusion (1000/2000 nmol min-1) evoked a significant increase in DeltaPAP and an up to 10-fold increase in Kf,c reaching the maximum extent of the observed effects significant earlier in the 2000 nmol min-1 group. ASA reduced DeltaPAPmax significantly to about 50% in corresponding groups and the increase in PAP and Kf,c occurred later in the ASA groups. (B) Neutrophil stimulation (PMN group/ASA group) evoked a rapid increase in DeltaPAP and MPO activity, while the changes in vascular permeability were rather moderate, but still significant. The release of MPO activity was similar in both groups. ASA significantly reduced the increase in DeltaPAP without affecting the release of MPO activity. Compared to baseline values, the preventive effects on vascular permeability increase reached level of significance as well. In summary, the described changes in pulmonary circulation caused by HOCl infusion or by neutrophil stimulation are significantly reduced by ASA. An involvement of cyclooxygenase products in the mediation of neutrophil-derived oxidative stress could be concluded.

Alterations of neutrophil L-selectin and CD18 expression by tobacco smoke: implications for periodontal diseases

Alterations in neutrophil functions by both chronic low levels of tobacco and by acute short-term higher levels of tobacco smoke, as encountered during the act of smoking, may play a role in the pathogenesis of periodontal diseases in smokers. Among the early migration events of neutrophil function is the alteration in surface expression of L-selectin and the CD11/18 integrins. In the present study we examined the effect of in vitro smoke exposure and nicotine alone on the expression of these 2 adhesion molecules in neutrophils from smokers and non-smokers. We also determined the physiological relevance of this in vitro system by assessing the levels of nicotine exposure in this in vitro system and comparing these levels to acute and chronic levels of nicotine in saliva and gingival crevicular fluid. Peripheral neutrophils were isolated from the blood of smokers (> 1 pack/d) and non-smokers and incubated in vitro with either cigarette smoke (0-5 min), 10(-7) M F-met-leu-phe, or nicotine alone at 1.62 mg/ml to 162 ng/ml (10(-2) M-10(-6) M). The neutrophils were then incubated with fluoresceine conjugated anti-Leu8 (L-selectin), anti-CD18 (CD18 integrin), or gamma-4 (non-specific control), fixed and analyzed by flow cytometry. With cigarette smoke exposure, there was an approximate 75% shedding of L-selectin in both smokers and non-smokers with no marked difference between groups at 1-5 min of smoke exposure. Cigarette smoke exposure resulted in a 15-20% increase in CD18 expression in both smokers and non-smokers. At all time points, there was slightly greater but statistically insignificant expression of CD18 integrin in non-smokers when compared to smokers. These patterns of CD18 increases and L-selectin shedding were similar in magnitude to incubations with 10(-7) M F-met-leu-phe. Acute smoke exposure resulted in elevation of nicotine in the smoke box to 529 ng/ml at 5 min, in saliva from 109.2 ng/ml before smoking to 1821.4 ng/ml after smoking, and in gingival crevicular fluid to 5961 ng/ml after smoking. No significant alterations in L-selectin or CD18 expression were noted with in vitro nicotine from 1.62 mg/ml to 162 ng/ml.

Alterations of neutrophil oxidative burst by in vitro smoke exposure: implications for oral and systemic diseases

Alterations of neutrophil functions by tobacco products may play a central role in the pathogenesis of periodontal diseases and several smoking-related systemic diseases. In the present study, we examined the in vitro effects of cigarette smoke on neutrophils at times and concentrations that may be encountered during smoke exposure. We measured the level of smoke exposure in the in vitro system by measuring the levels of nicotine and comparing these to levels in the oral cavity in smokers before and after smoking. We examined both the unstimulated and stimulated release of 2 oxidative burst products: superoxide (O-2) and hydrogen peroxide (H2O2). Salivary washings were collected from 7 smokers (> 1 pack/day) before smoking a cigarette. Immediately after they smoked a cigarette, a second set of washings was collected. In vitro exposure to smoke involved incubating aliquots of neutrophils in phosphate-buffered saline for 1 to 5 minutes. Nicotine and cotinine levels were quantitated using gas chromatography, with detection by electron impact mass spectrometry. Peripheral neutrophils were isolated from medically healthy non-smoking volunteers via a double-density gradient technique and incubated in vitro with whole cigarette smoke for 0 to 5 minutes. Phorbol myristate acetate (PMA; 10(-7) M) was used to stimulate half of the cell aliquots. Superoxide generation was assessed through the superoxide dismutase (SOD) inhibitable reduction of ferricytochrome c. H2O2 production was assessed through the H2O2-dependent breakdown of dichlorofluorescin diacetate to its fluorophore and measured by flow cytometry. There was a marked elevation in salivary nicotine concentration from before smoking (mean: 80.8 ng) to after smoking (mean 1,685 ng/mL). In the in vitro smoke box system, there was a time-related elevation in nicotine from 1 to 5 minutes (50-->136 ng/mL). In PMA-stimulated cells exposed to smoke, there was a time-related inhibition of both superoxide and H2O2 production. However, in unstimulated cells exposed to smoke, there was a time-related increase in the release of superoxide and H2O2. A novel finding in unstimulated cells exposed to smoke was that there appeared to be 2 distinct populations of cells--one of "high" H2O2 producers and one of "low" H2O2 producers. The proportion of high H2O2 producers increased relative to smoke exposure. The relative production of H2O2 in the unstimulated high producers was comparable to PMA-stimulated cells at 5 minutes. This release of superoxide and H2O2 in unstimulated cells exposed to smoke may alter the pathogenic processes both in periodontal diseases and other systemic diseases.

Sulfonamide-based hydroxamic acids as potent inhibitors of mouse macrophage metalloelastase

The structural requirements of sulfonamide-based hydroxamic acid 1 for inhibition of macrophage metalloelastase (MME) were investigated. A short aliphatic group at the R2 position together with an aromatic group at the R3 position significantly improved the inhibitory activity. Compounds 32, 34, and 40 were the most potent inhibitors of MME with IC50 values between 5 and 6 nM.

Nicotine-stimulated elastase activity release by neutrophils in patients with abdominal aortic aneurysms

Elevated elastase activity in patients with chronic obstructive pulmonary disease (COPD) is attributable to the direct effect of nicotine. COPD is also known to be an independent predictor of abdominal aortic aneurysm (AAA) growth and rupture. The purpose of this study is to determine the effect of nicotine on elastase activity release from neutrophils of AAA patients. Human neutrophils were extracted from the blood of subjects in the following six groups, n = 10 in each group: smoking AAA (SAAA), nonsmoking AAA (NSAAA), smoking aortic occlusive disease (SAOD), nonsmoking aortic occlusive disease (NSAOD), smoking controls (SC), and nonsmoking controls (NSC). After incubation with varying nicotine concentrations (0-1000 microg/ml), the released elastase activity was determined. There is generally an elevation in elastase activity release by neutrophils of smokers compared to nonsmokers. Nicotine exposure stimulated increased elastase activity release in AOD and AAA, and the increase was especially pronounced in the SAAA and SAOD groups. The elevation was greatest in the SAAA group while the release was lowest in the NSAOD group. There is a direct correlation between elastase activity release and nicotine concentration. The data suggest that COPD and AAA development, which may occur by similar initial mechanisms may also be aggravated by nicotine-induced neutrophil elastase activity release. In addition, the results indicate that nicotine is playing an active role in the development of vascular disease by inducing neutrophils to release elastase activity.

Spinocerebellar ataxia type 1 and familial spontaneous pneumothorax

We report two siblings with spinocerebellar ataxia type 1 (SCA1) who experienced frequent episodes of spontaneous pneumothorax. Radiologic findings indicated underlying degenerative changes in the lungs. This suggests a possible pathophysiologic relationship between SCA1 and familial occurrence of spontaneous pneumothorax.

Protective effects of an aptamer inhibitor of neutrophil elastase in lung inflammatory injury

Neutrophils play an important part in the development of acute inflammatory injury. Human neutrophils contain high levels of the serine protease elastase, which is stored in azurophilic granules and is secreted in response to inflammatory stimuli. Elastase is capable of degrading many components of extracellular matrix [1-4] and has cytotoxic effects on endothelial cells [5-7] and airway epithelial cells. Three types of endogenous protease inhibitors control the activity of neutrophil elastase, including alpha-1 protease inhibitor (alpha-1PI), alpha-2 macroglobulin and secreted leukoproteinase inhibitor (SLPI) [8-10]. A disturbed balance between neutrophil elastase and these inhibitors has been found in various acute clinical conditions (such as adult respiratory syndrome and ischemia-reperfusion injury) and in chronic diseases. We investigated the effect of NX21909, a selected oligonucleotide (aptamer) inhibitor of elastase, in an animal model of acute lung inflammatory disease [11-14]. This inhibitor was previously selected from a hybrid library of randomized DNA and a small-molecule irreversible inhibitor of elastase (a valine diphenyl ester phosphonate, Fig. 1), by the blended SELEX process [15]. We show that NX21909 inhibits lung injury and neutrophil influx in a dose-dependent manner, the first demonstration of efficacy by an aptamer in an animal disease model.

Reamed femoral nailing in patients with multiple injuries. Adverse effects of tourniquet use

Limb reperfusion after tourniquet ischemia causes pulmonary microvascular injury. Similarly, microembolization, like that associated with reamed femoral nailing, can induce pulmonary microvascular injury. Both processes result in increased pulmonary capillary membrane permeability and edema. However, the association between femoral nailing followed by tourniquet ischemia and clinical lung injury has not been described. The authors reviewed 72 patients with femoral shaft fractures and tibial or ankle fractures requiring internal fixation between 1987 and 1993. All femoral shaft fractures were treated with reamed intramedullary nails. Patients were divided into groups, based on whether the tibial or ankle injury was managed surgically with (Group T, 34 patients) or without (Group NT, 38 patients) a tourniquet. Group T was subdivided based on tourniquet time: T1, less than or equal to 90 minutes; T2, greater than 90 minutes. Groups were matched for injury severity. Group NT had fewer ventilator dependent days and intensive care days than Group T (NT: ventilator dependent days, 2.5 +/- 5.2; intensive care days, 3.9 +/- 6.5; T: 5.1 +/- 6.4; intensive care days, 6.7 +/- 6.6). Ventilator dependent days and intensive care days increased with increasing tourniquet time (T1: ventilator dependent days, 3.2 +/- 3.6; intensive care days, 5.4 +/- 4.6; T2: ventilator dependent days, 7.5 +/- 8.5; intensive care days, 8.5 +/- 8.5), suggesting that in patients with multitrauma, combining reamed femoral nailing with fracture fixation under tourniquet control increases pulmonary morbidity. Further investigation to measure pulmonary injury associated with ischemia reperfusion and intramedullary nailing in patients with multitrauma is warranted.

Inhibition of human leukocyte proteinase 3 by a novel recombinant serine proteinase inhibitor (LEX032)

The interaction of a bioengineered serpin (LEX032) with human leukocyte proteinase 3 (PR 3) has been investigated. LEX032 was found to be a time-dependent inhibitor of PR 3, forming a highly-stable enzyme-inhibitor complex (Ki 12 nM).

Highly potent irreversible inhibitors of neutrophil elastase generated by selection from a randomized DNA-valine phosphonate library

We incorporated a phosphonate irreversible inhibitor of neutrophil elastase into a randomized DNA library and, using the SELEX process, iteratively selected these assemblies for the most potent elastase inhibitors. The inhibitors were selected against purified elastase and against secreted elastase in the presence of activated neutrophils. Very active aptamer inhibitors were obtained by both methods, with second-order rate constants for inactivation of human neutrophil elastase ranging (1-3) x 10(8) M(-1) min(-1). These rates exceed those of any reported irreversible inhibitor of elastase and exceed the previous best phosphonate inhibitors by 80-fold. The selected inhibitors are also significantly more potent than alpha-1 proteinase inhibitor in blocking degradation of elastin by activated neutrophils. In contrast to a previous experiment [Smith et al. (1995) Chem. Biol. 2, 741-750], a single-enantiomer form of the valyl phosphonate was used rather than a racemic mixture. Our analysis shows that this use of a chirally resolved valyl phosphonate results in selection of much more potent inhibitors and that these inhibitors specifically potentiate a single enantiomeric form of the phosphonate.

In vitro selection of RNA-based irreversible inhibitors of human neutrophil elastase

INTRODUCTION

We describe a new approach to drug discovery which joins the technologies of medicinal and combinatorial chemistry, allowing selection of the most active variant of a lead compound from a large (> 10(12)) pool. A small-molecule covalent inhibitor of elastase was coupled to a randomized pool of RNA, and this assembly was iteratively selected for oligonucleotide sequences that promote the covalent reaction of the inhibitor with the human neutrophil elastase (hNE) active site.

RESULTS

Incorporation of the covalent inhibitor into the randomized pool increases the second-order rate of inactivation of hNE by approximately 15-fold; sequences selected from this pool show an additional approximately 20-fold increase in activity. The relative rate of cross-reaction with another serine protease, cathepsin G, was reduced > 100-fold. Low doses of the inhibitor were found to prevent lung damage inflicted by human neutrophils in an isolated rat lung model of acute respiratory distress syndrome (ARDS).

CONCLUSIONS

This result supports the hypothesis that neutrophil elastase is a significant effector of inflammatory disease. More generally, our findings demonstrate that blending small molecules into combinatorial libraries is a feasible method of drug discovery.

The value of polymorphonuclear elastase in adult respiratory distress syndrome

The clinical usefulness of quantitative plasma polymorphonuclear elastase (PMN-elastase) determinations as prognostic markers of adult respiratory distress syndrome (ARDS) in polytraumatized patients was analyzed. PMN-elastase and C-reactive protein (CRP) levels were determined in 55 polytraumatized patients admitted into the Intensive Care Unit. Eight patients developed ARDS and 47 patients did not. These parameters were also analyzed in a control group (n = 34). PMN-elastase levels in ARDS cases reached significantly higher values than in patients who did not develop this syndrome (P < 0.01). We conclude that the increase in plasma PMN-elastase levels can be useful in predicting the development of ARDS in polytraumatized patients, in instituting prophylactic actions and monitoring the course of the disease in these high risk patients. This test is easily adaptable to the routine of any hospital laboratory.

Measurements of plasma elastase alpha 1-proteinase inhibitor complexes in patients receiving cancer chemotherapy with granulocyte colony-stimulating factor

We monitored the plasma elastase alpha 1-proteinase inhibitor complex levels in 21 patients with primary lung cancer who received combination chemotherapy with or without recombinant human granulocyte colony-stimulating factor (rhG-CSF), and 15 normal nonsmokers as controls. Of the 21 patients, 14 received combination chemotherapy without rhG-CSF (among them, 6 developed pneumonia) and 7 received combination chemotherapy with rhG-CSF (among them, 1 developed pneumonia). We measured peripheral WBC counts, C-reactive protein (CRP) levels, plasma elastase alpha 1-proteinase inhibitor complex (complex) levels, and complex/WBC values during cancer chemotherapy. In patients who received cancer chemotherapy without rhG-CSF and had no complications (n = 8), WBC values decreased after chemotherapy, and then gradually increased. Complex levels also decreased slightly after chemotherapy and gradually recovered. The value obtained from dividing the complex concentration by WBC count (complex/WBC value) remained stable during cancer chemotherapy. In patients who received cancer chemotherapy with rhG-CSF and had no complications (n = 6), WBC values decreased after chemotherapy, and then rapidly increased to abnormally high values. Complex levels also decreased slightly after chemotherapy and rapidly increased to abnormally high values together with the WBC counts. The complex/WBC values remained stable during cancer chemotherapy. In patients who developed pneumonia during cancer chemotherapy with or without rhG-CSF (n = 7), their complex levels, complex/WBC values, and CRP levels were elevated at the onset of pneumonia. The maximum complex levels (the highest levels during chemotherapy) were significantly higher in patients who received cancer chemotherapy with rhG-CSF and did not develop pneumonia (583.1 +/- 114.5 ng/mL) and in patients who developed pneumonia during cancer chemotherapy (516.7 +/- 113.2 ng/mL), compared with normal nonsmokers (130.2 +/- 5.5, p < 0.01) and patients who received cancer chemotherapy without rhG-CSF and did not develop complications (211.5 +/- 23.3, p < 0.01). The maximum complex/WBC values were not increased in patients who received cancer chemotherapy with rhG-CSF (0.08 +/- 0.01) and patients who received cancer chemotherapy without rhG-CSF (0.092 +/- 0.01, p < 0.01). The maximum complex/WBC values were significantly higher in patients with pneumonia (0.56 +/- 0.12) compared with normal nonsmokers (0.026 +/- 0.002, p < 0.01) and patients without complications. These findings suggest that although rhG-CSF increases total plasma elastase burden, increased release of neutrophil elastase from individual neutrophils does not take place in vivo in the absence of pneumonia.

Effects of progestogens on human endometrium

The effect of progestogens on endometrium depends on the dosage, duration of exposure, the type of progestogen, and the presence or absence of estrogen. Mechanisms of progestogen action in endometrium are mainly expressed through the binding of hormone to specific nuclear receptors. Exogenous progestogens seem to influence the hypothalamic-pituitary-ovarian-endometrial axis differently in different individuals. Endogenous hormones resulting from ovarian secretion have effects on the endometrium independent of, and in combination with, exogenous progestogens. Endometrial morphological changes with progestogens vary from suppression of endometrial glandular growth, through stromal decidualization and leukocytic infiltration to glandular atrophy and stromal focal necrosis. In a minority of cases resulting from very prolonged treatment connective tissue fibers increase to some degree and may be accompanied by endometrial fibrosis and calcification. Clinical and histological data have demonstrated that all these changes, including fibrosis and calcification, return to normal in a short period after discontinuing treatment. Endometrial changes during progestogen therapy are often accompanied by leukocyte infiltration, especially when necrosis occurs. White blood cells constitute an important component of normal endometrium. The number and the type of leukocytes change during the normal menstrual cycle apparently related to circulating ovarian hormonal changes. Exogenous progestogens also influence white blood cells, by increasing total numbers and certain specific cell types. Changes in endometrial white blood cell function as a consequence of exogenous progestogens are unclear, but it is possible that the increase of leukocyte infiltration resulting from exogenous progestogens plays an important role in evoking progestational endometrial necrosis.

Nicotine effects on neutrophil F-actin formation and calcium release: implications for tobacco use and pulmonary diseases

Alterations in neutrophil functions by tobacco components may play a pivotal role in pulmonary emphysema. This study examined the role of nicotine in altering F-actin formation and calcium (Ca2+) release (two early events in neutrophil motility). The effects of these alterations on the motile function of phagocytosis were also examined. Human peripheral neutrophils from medically healthy nonsmoking subjects were incubated with nicotine at concentrations normally encountered during acute exposure to cigarette smoke (10(-2) to 10(-5) M) and/or the chemotactic peptide FLPEP (10(-7) M). Relative F-actin stain was determined by NBD phallacidin staining followed by flow cytometry. Intracellular Ca2+ was determined by INDO-1 AM loading followed by emission ratio quantitation by fluorometry. Phagocytosis was determined by the % phagocytic cells with carboxylated microspheres. Incubation of neutrophils with varying concentrations of nicotine resulted in a significant elevation of the relative F-actin stain at 30 s at 10(-2) and 10(-3) M (p < .05, ANOVA) and at 30 min at 10(-2) to 10(-4) M (p < 0.05). In time course studies with 10(-7) M FLPEP stimulation, there was a approximately 325% rise in relative F-actin stain at 30-60 s, followed by a gradual decrease to near baseline levels. There was an immediate rise in Ca2+ to approximately 150% over baseline values, followed by a gradual decrease to baseline. By contrast, stimulation with nicotine demonstrated a approximately 105% increase in relative F-actin staining at 10(-2) M (p < .001, ANOVA) and a smaller increase at 10(-3) M, which remained elevated up to 600 s. Intracellular Ca2+ levels also rose in a dose-dependent manner with an increased of 700% over baseline with 10(-2) M nicotine, and remained elevated up to 600 s. Coincubation with both FLPEP and nicotine demonstrated additive effects in relative F-actin staining at both maximal and submaximal concentrations. Preincubation with 10(-2) or 10(-3) M nicotine suppressed the % phagocytic cells by 32% and 16%, respectively (p < .001, ANOVA) with only a 1-4% reduction in cell viability (trypan blue exclusion). The results demonstrate that the concentration of nicotine during acute cigarette exposure can directly stimulate neutrophil F-actin formation and intracellular Ca2+ release by a mechanism different from peptide stimulation. The alteration of these two pivotal neutrophil signaling events by nicotine may in turn alter other neutrophil functions in tobacco-related pulmonary emphysema.

Pathogenesis of fibrosis in acute lung injury

The anatomic changes that occur in response to acute lung injury significantly impair gas exchange. As is the case with skin wounds, a fibroproliferative response follows lung injury. In the lungs, however, this can result in life-threatening obliteration of alveolar air spaces. A better understanding of the mechanisms involved in lung repair may allow the development of therapies that regulate the fibroproliferative response. Studies from our laboratory have identified a peptide in bronchoalveolar lavage fluid from patients with acute lung injury that promotes the migration and replication of lung fibroblasts. This peptide is related to platelet-derived growth factor (PDGF) antigenically as well as by receptor-binding criteria; its molecular weight is 14 kilodaltons (kDa) as compared to 29 kDa for PDGF. Despite the potent activity of the 14 kDa peptide, however, such a growth signal may not be absolutely required for tissue granulation. The possibility that lung fibroblasts from patients with acute lung injury might be capable of dividing without exogenous stimulation will be examined. Another theoretical consideration is the signals that regulate termination of the fibroproliferative response. Insights into the molecular mechanisms involved in lung repair may result in therapies that modulate the sometimes maladaptive fibroproliferative response following acute lung injury.