New perspectives on basic mechanisms in lung disease. 2. Neutrophil traffic in the lungs: role of haemodynamics, cell adhesion, and deformability

The role of G protein-coupled receptor in neutrophil dysfunction during sepsis-induced acute respiratory distress syndrome

Sepsis is defined as a life-threatening dysfunction due to a dysregulated host response to infection. It is a common and complex syndrome and is the leading cause of death in intensive care units. The lungs are most vulnerable to the challenge of sepsis, and the incidence of respiratory dysfunction has been reported to be up to 70%, in which neutrophils play a major role. Neutrophils are the first line of defense against infection, and they are regarded as the most responsive cells in sepsis. Normally, neutrophils recognize chemokines including the bacterial product N-formyl-methionyl-leucyl-phenylalanine (fMLP), complement 5a (C5a), and lipid molecules Leukotriene B4 (LTB4) and C-X-C motif chemokine ligand 8 (CXCL8), and enter the site of infection through mobilization, rolling, adhesion, migration, and chemotaxis. However, numerous studies have confirmed that despite the high levels of chemokines in septic patients and mice at the site of infection, the neutrophils cannot migrate to the proper target location, but instead they accumulate in the lungs, releasing histones, DNA, and proteases that mediate tissue damage and induce acute respiratory distress syndrome (ARDS). This is closely related to impaired neutrophil migration in sepsis, but the mechanism involved is still unclear. Many studies have shown that chemokine receptor dysregulation is an important cause of impaired neutrophil migration, and the vast majority of these chemokine receptors belong to the G protein-coupled receptors (GPCRs). In this review, we summarize the signaling pathways by which neutrophil GPCR regulates chemotaxis and the mechanisms by which abnormal GPCR function in sepsis leads to impaired neutrophil chemotaxis, which can further cause ARDS. Several potential targets for intervention are proposed to improve neutrophil chemotaxis, and we hope that this review may provide insights for clinical practitioners.

Nonionic surfactant attenuates acute lung injury by restoring epithelial integrity and alveolar fluid clearance

Introduction: Acute lung injury (ALI) has a great impact and a high mortality rate in intensive care units (ICUs). Excessive air may enter the lungs, causing pulmonary air embolism (AE)-induced ALI. Some invasive iatrogenic procedures cause pulmonary AE-induced ALI, with the presentation of severe inflammatory reactions, hypoxia, and pulmonary hypertension. Pulmonary surfactants are vital in the lungs to reduce the surface tension and inflammation. Nonionic surfactants (NIS) are a kind of surfactants without electric charge on their hydrophilic parts. Studies on NIS in AE-induced ALI are limited. We aimed to study the protective effects and mechanisms of NIS in AE-induced ALI. Materials and methods: Five different groups (n = 6 in each group) were created: sham, AE, AE + NIS pretreatment (0.5 mg/kg), AE + NIS pretreatment (1 mg/kg), and AE + post-AE NIS (1 mg/kg). AE-induced ALI was introduced by the infusion of air via the pulmonary artery. Aerosolized NIS were administered via tracheostomy. Results: Pulmonary AE-induced ALI showed destruction of the alveolar cell integrity with increased pulmonary microvascular permeability, pulmonary vascular resistance, pulmonary edema, and lung inflammation. The activation of nuclear factor-κB (NF-κB) increased the expression of pro-inflammatory cytokines, and sodium-potassium-chloride co-transporter isoform 1 (NKCC1). The pretreatment with NIS (1 mg/kg) prominently maintained the integrity of the epithelial lining and suppressed the expression of NF-κB, pro-inflammatory cytokines, and NKCC1, subsequently reducing AE-induced ALI. Conclusions: NIS maintained the integrity of the epithelial lining and suppressed the expression of NF-κB, pro-inflammatory cytokines, and NKCC1, thereby reducing hyperpermeability, pulmonary edema, and inflammation in ALI.

Endothelial Responses in Sepsis

Endothelial cells (ECs) are vascular, nonconventional immune cells that play a major role in the systemic response after bacterial infection to limit its dissemination. Triggered by exposure to pathogens, microbial toxins, or endogenous danger signals, EC responses are polymorphous, heterogeneous, and multifaceted. During sepsis, ECs shift toward a proapoptotic, proinflammatory, proadhesive, and procoagulant phenotype. In addition, glycocalyx damage and vascular tone dysfunction impair microcirculatory blood flow, leading to organ injury and, potentially, life-threatening organ failure. This review aims to cover the current understanding of the EC adaptive or maladaptive response to acute inflammation or bacterial infection based on compelling recent basic research and therapeutic clinical trials targeting microvascular and endothelial alterations during septic shock.

Chronic Airway Allergy Induces Pro-Inflammatory Responses in the Brain of Wildtype Mice but Not 3xTgAD Mice

The effects of systemic inflammation on the pathogenesis of Alzheimer's disease (AD) are not clarified, both beneficial and deleterious effects being reported. Allergy is accompanied by a systemic inflammatory response and some epidemiological studies have reported a positive association between a history of allergy/asthma and dementia. To investigate whether chronic airway allergy influences the inflammatory status in the brain, AD-like pathology, and behaviour in relation to AD, we induced chronic airway allergy in triple transgenic AD (3xTgAD) and wildtype (WT) mice by repeated exposure to ovalbumin (OVA) as allergen. Behavioural tests relevant for hippocampus-dependent behaviour were performed. We found that allergy significantly increased the brain levels of immunoglobulin (Ig) G, IgE. In 3xTgAD mice, allergy increased the levels of decay accelerating factor and decreased the phosphorylation of p38. In contrast, allergy increased the levels of interleukin (IL)-1β and complement component 1q (C1q) in WT mice. Bronchoalveolar lavage fluid analysis confirmed eosinophilia in both genotypes, but the basal levels of eosinophils were lower in 3xTgAD mice. In summary, allergy induced predominantly anti-inflammatory effects in 3xTgAD mice, and pro-inflammatory effects in WT mice, thus being another potential factor to be considered when studying AD pathogenesis.

Immune cells as tumor drug delivery vehicles

This review article describes the use of immune cells as potential candidates to deliver anti-cancer drugs deep within the tumor microenvironment. First, the rationale of using drug carriers to target tumors and potentially decrease drug-related side effects is discussed. We further explain some of the current limitations when using nanoparticles for this purpose. Next, a comprehensive step-by-step description of the migration cascade of immune cells is provided as well as arguments on why immune cells can be used to address some of the limitations associated with nanoparticle-mediated drug delivery. We then describe the benefits and drawbacks of using red blood cells, platelets, granulocytes, monocytes, macrophages, myeloid-derived suppressor cells, T cells and NK cells for tumor-targeted drug delivery. An additional section discusses the versatility of nanoparticles to load anti-cancer drugs into immune cells. Lastly, we propose increasing the circulatory half-life and development of conditional release strategies as the two main future pillars to improve the efficacy of immune cell-mediated drug delivery to tumors.

Effects of low-intensity and high-intensity cycling with diesel exhaust exposure on soluble P-selectin, E-selectin, I-CAM-1, VCAM-1 and complete blood count

BACKGROUND

Exposure to particulate matter 2.5 μm or less (PM2.5) that contains transition metals may play a role in systemic oxidative stress and inflammation. Exposure to diesel exhaust (DE) can increase adhesion molecules, which are important in the inflammatory response; however, it is unclear how exercising in DE affects adhesion molecules and how exercise intensity modulates this response.

AIM

To determine how DE exposure during exercise of varying intensities affects adhesion molecules and markers of systemic inflammation.

METHODS

Eighteen males performed 30 min cycling bouts at low intensity and high intensity (30% and 60% of power at VO2peak (peak oxygen consumption) and a control condition (rest)). Each trial was performed once breathing filtered air (FA) and once breathing DE (300 μg/m3 of PM2.5, six trials in total). Prior to, immediately post, 1 and 2 hours post exposure, blood was drawn to measure parameters of a complete blood count and soluble (s) platelet-Selectin, endothelin-Selectin, intracellular cell adhesion molecule (sICAM)-1 and vascular cell adhesion molecule (sVCAM)-1. Data were analysed using repeated-measures analysis of variance.

RESULTS

Two hours following high-intensity exercise, sICAM-1 was significantly less in DE compared with FA (p=0.008). Immediately following rest (p=0.013) and high-intensity exercise (p=0.042) in DE, sICAM-1 was significantly greater than immediately following low-intensity exercise in DE. There were no significant differences in other markers between DE and FA.

CONCLUSIONS

Based on this study, healthy individuals may not experience an acute increase in adhesion molecules and systemic inflammatory markers from exercising in DE compared with FA, and higher exercise intensities do not appear to increase the likelihood that DE will affect adhesion molecules and systemic inflammatory markers.

Neutrophils disturb pulmonary microcirculation in sepsis-induced acute lung injury

The lung is highly vulnerable during sepsis, yet its functional deterioration accompanied by disturbances in the pulmonary microcirculation is poorly understood. This study aimed to investigate how the pulmonary microcirculation is distorted in sepsis-induced acute lung injury (ALI) and reveal the underlying cellular pathophysiologic mechanism.

Using a custom-made intravital lung microscopic imaging system in a murine model of sepsis-induced ALI, we achieved direct real-time visualisation of the pulmonary microcirculation and circulating cells in vivo. We derived the functional capillary ratio (FCR) as a quantitative parameter for assessing the fraction of functional microvasculature in the pulmonary microcirculation and dead space.

We identified that the FCR rapidly decreases in the early stage of sepsis-induced ALI. The intravital imaging revealed that this decrease resulted from the generation of dead space, which was induced by prolonged neutrophil entrapment within the capillaries. We further showed that the neutrophils had an extended sequestration time and an arrest-like dynamic behaviour, both of which triggered neutrophil aggregates inside the capillaries and arterioles. Finally, we found that Mac-1 (CD11b/CD18) was upregulated in the sequestered neutrophils and that a Mac-1 inhibitor restored the FCR and improved hypoxaemia.

Using the intravital lung imaging system, we observed that Mac-1-upregulated neutrophil aggregates led to the generation of dead space in the pulmonary microcirculation that was recovered by a Mac-1 inhibitor in sepsis-induced ALI.

Neutrophils induce dead space in the pulmonary microcirculation in sepsis-induced ALI, recovered by a Mac-1 inhibitorhttp://ow.ly/vUzO30nbUyU

CXCR4 identifies transitional bone marrow premonocytes that replenish the mature monocyte pool for peripheral responses

It is well established that Ly6C^hi monocytes develop from common monocyte progenitors (cMoPs) and reside in the bone marrow (BM) until they are mobilized into the circulation. In our study, we found that BM Ly6C^hi monocytes are not a homogenous population, as current data would suggest. Using computational analysis approaches to interpret multidimensional datasets, we demonstrate that BM Ly6C^hi monocytes consist of two distinct subpopulations (CXCR4^hi and CXCR4^lo subpopulations) in both mice and humans. Transcriptome studies and in vivo assays revealed functional differences between the two subpopulations. Notably, the CXCR4^hi subset proliferates and is immobilized in the BM for the replenishment of functionally mature CXCR4^lo monocytes. We propose that the CXCR4^hi subset represents a transitional premonocyte population, and that this sequential step of maturation from cMoPs serves to maintain a stable pool of BM monocytes. Additionally, reduced CXCR4 expression on monocytes, upon their exit into the circulation, does not reflect its diminished role in monocyte biology. Specifically, CXCR4 regulates monocyte peripheral cellular activities by governing their circadian oscillations and pulmonary margination, which contributes toward lung injury and sepsis mortality. Together, our study demonstrates the multifaceted role of CXCR4 in defining BM monocyte heterogeneity and in regulating their function in peripheral tissues.

The role of vagus nerve overactivity in the increased incidence of pneumonia following traumatic brain injury

Nosocomial infections, pneumonia in particular, are well-known complications of traumatic brain injury (TBI), which are associated with a worse neurological outcome. This review aims to explore the role of vagus nerve activity in immunomodulation as a causative factor. A MEDLINE search revealed numerous reports published over the last decade describing the "cholinergic anti-inflammatory pathway" between the vagus nucleus and leukocyte activity. Using a combination of lipopolysaccharide stimulation and vagotomy, it has been shown that the parasympathetic fibres terminating in the spleen reduce tumour necrosis factor production. Further pharmacological and receptor knockout studies have identified the α7 subtype of nicotinic receptors as the likely target for this. Vagal activity also induces changes in neutrophil chemotaxis through altered expression of the CD11b integrin which is abolished by splenectomy. By extrapolating this evidence we suggest a possible mechanism for immunosuppression following TBI which also has the potential to be targeted to reduce the incidence of pneumonia. Whilst there is strong supporting evidence for the role of vagal nerve overactivity in post-TBI pneumonia, there have yet to be any clinical investigations and further study is required.

Oxidative/Nitrosative stress and the pathobiology of chronic obstructive pulmonary disease

The understanding of the pathobiology of Chronic Obstructive Pulmonary Disease (COPD) has undergone a major change in the past three decades. The classical 'protease-antiprotease' hypothesis still holds true, nevertheless, the sequence of the biochemical events which lead to the protease/antiprotease imbalance have been unraveled. For instance, tobacco smoke, a primary risk factor for COPD, contains a plethora of reactive Oxygen/Nitrogen Species (ROS/RNS) that serve to initiate the oxidant/antioxidant imbalance in the respiratory tract of chronic smokers, a phenomenon that is amplified if certain other risk factors co-exist (e.g. a genetic deficiency of the major antiproteases, a suboptimal antioxidant defense system, airway hyper responsiveness etc.). The inflammatory response that ensues as a result of the initial occult exogenous oxidative/ nitrosative stress becomes a secondary endogenous source of ROS/RNS. This perpetuates the ongoing lung damage, even though the primary insult may no longer be present (abstinence). Depletion of the pulmonary antioxidants, damage to the local antiprotease protective screen, a decreased immune response, hypersecretion of mucus, superadded infections, oxygen therapy-induced oxidant production, etc. are some of the critical factors which account for the oxidative/ nitrosative stress-mediated pulmonary as well as extrapulmonary features of COPD. In the light of the recent developments, remarkable efforts are being made, either to develop novel therapeutic strategies or to improve the existing ones, which are aimed at treating different aspects of the disease. Thus, it is reasonable to recommend antioxidants as a useful adjunct to the more conventional treatment options, keeping in view the 'oxidant/antioxidant' hypothesis as a unifying theme for the 'protease/antiprotease' theory of COPD.

Innate immune receptors on neutrophils and their role in chronic lung disease

Neutrophils, the prototypic cells of the innate immune system, are recruited to infected sites to protect the human body from invading pathogens. To accomplish this function, neutrophils sense pathogens and endogenous damage-associated molecules via innate immune receptors, such as Toll-like receptors (TLRs) and other pattern recognition receptors. This defence function is essential for the pulmonary microenvironment where the host is faced with millions of particles and pathogens inhaled daily. Chronic lung diseases, such as cystic fibrosis or chronic obstructive pulmonary disease are characterized by a neutrophil accumulation and chronic bacterial colonization of the airways. Consequently, insights into the role of TLRs on neutrophils in chronic lung diseases are of high relevance for further diagnostic and therapeutic approaches. Here we summarize and discuss recent advances in the expression, regulation and functional role of TLRs on neutrophils in chronic lung diseases.

Cigarette smoke-induced emphysema in A/J mice is associated with pulmonary oxidative stress, apoptosis of lung cells, and global alterations in gene expression

Cigarette smoking is the major risk factor for developing chronic obstructive pulmonary disease, the fourth leading cause of deaths in the United States. Despite recent advances, the molecular mechanisms involved in the initiation and progression of this disease remain elusive. We used Affymetrix Gene Chip arrays to determine the temporal alterations in global gene expression during the progression of pulmonary emphysema in A/J mice. Chronic cigarette smoke (CS) exposure caused pulmonary emphysema in A/J mice, which was associated with pronounced bronchoalveolar inflammation, enhanced oxidative stress, and increased apoptosis of alveolar septal cells. Microarray analysis revealed the upregulation of 1,190, 715, 260, and 246 genes and the downregulation of 1,840, 730, 442, and 236 genes in the lungs of mice exposed to CS for 5 h, 8 days, and 1.5 and 6 mo, respectively. Most of the genes belong to the functional categories of phase I genes, Nrf2-regulated antioxidant and phase II genes, phase III detoxification genes, and others including immune/inflammatory response genes. Induction of the genes encoding multiple phase I enzymes was markedly higher in the emphysematous lungs, whereas reduced expression of various cytoprotective genes constituting ubiquitin-proteasome complex, cell survival pathways, solute carriers and transporters, transcription factors, and Nrf2-regulated antioxidant and phase II-responsive genes was noted. Our data indicate that the progression of CS-induced emphysema is associated with a steady decline in the expression of various genes involved in multiple pathways in the lungs of A/J mice. Many of the genes discovered in this study could rationally play an important role in the susceptibility to CS-induced emphysema.

Pulmonary mechanic and lung histology injury induced by Crotalus durissus terrificus snake venom

In the present work we investigated the effects of Crotalus durissus terrificus venom (CdtV) on the pulmonary mechanic events [static and dynamic elastance, resistive (DeltaP1) and viscoelastic pressures (DeltaP2)] and histology after intramuscular injection of saline solution (control) or venom (0.6 microg/g). The static and dynamic elastance values were increased significantly after 3 h of venom inoculation, but were reduced at control values in the other periods studied. The DeltaP1 values that correspond to the resistive properties of lung tissue presented a significant increase after 6h of CdtV injection, reducing to basal levels 12h after the venom injection. In DeltaP2 analysis, correspondent to viscoelastic components, an increase occurred 12 h after the venom injection, returning to control values at 24 h. CdtV also caused an increase of leukocytes recruitment (3-24 h) to the airways wall as well as to the lung parenchyma. In conclusion, C. durissus terrificus rattlesnake venom leads to lung injury which is reverted, after 24 h of inoculation.

Attenuation of bleomycin-induced lung injury and oxidative stress by N-acetylcysteine plus deferoxamine

Reactive oxygen species (ROS) play an important role in the pathogenesis of pulmonary injury and antioxidant therapy may be useful with impaired oxidative defense mechanism. This study examines the effect of N-acetylcysteine (NAC) and deferoxamine (DFX) on inflammatory indicators and oxidative stress in the lungs of mice exposed to bleomycin (BLM). The animals received endotracheally a single dose of BLM (2.5 U/kg body weight dissolved in 0.25 ml of 0.9% NaCl) or saline (0.9% NaCl) and were divided into eight groups (n=8): saline; BLM; saline+NAC; BLM+NAC; saline+DFX; BLM+DFX; saline+NAC+DFX; BLM+NAC+DFX. Treatments with NAC (20mg/kg) or DFX (30 mg/kg) were administered for 60 days after BLM exposure. Lactate dehydrogenase (LDH) activity and total cell count, neutrophil and protein concentration were determined in the bronchoalveolar lavage fluid (BALF). Lipid peroxidation thiobarbituric acid-reactive species (TBARS), oxidative protein damage (carbonyl contents), and catalase and superoxide dismutase activities were determined in the lung tissue. BLM administration resulted in lung lesion as determinated lung histology, which is almost completely prevented by NAC plus DFX. The results of total cell counts and neutrophils and LDH increased after BLM exposure and were reduced with NAC. DFX and NAC plus DFX also caused a significant decrease of LDH activity. The increased malondialdehyde equivalents and carbonyl contents in lung tissue produced by BLM were also prevented by NAC plus DFX. However, the isolated use of NAC increased lipid peroxidation. SOD activity increased after BLM exposure only in the group treated with DFX and catalase activity not was altered in the presence of BLM. Data presented here indicates that the isolated use of NAC had limited effects on BLM-induced pulmonary oxidative stress in mice. The use of DFX improves the defense response and in association with NAC may be a good alternative in the treatment or prevention of diseases that have ROS and iron involved in their pathogenesis.

Increased granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) levels in BAL fluid from patients with sulfur mustard gas-induced pulmonary fibrosis

The objective of this article was to show the role of cytokines in the pathogenesis of pulmonary fibrosis due to sulfur mustard gas inhalation. Eighteen veterans with mustard gas-induced pulmonary fibrosis and 18 normal patients were used as controls. Bronchoalveolar larvage (BAL) and analyses of BAL fluids for cellular and cytokine levels were performed. There was a significant difference in granulocyte colony stimulating factor (G-CSF) level in the BAL fluid of patients and the controls (p < 0.0001). Granulocyte-macrophage colony stimulating pulmonary fibrosis (GM-CSF) BAL levels were significantly increased in patients with pulmonary fibrosis (PF) in comparison with controls (p < 0.0001). Patients with PF have highly significant increases in IL-8 level compared to controls (87.94 +/- 59.63 vs. 8.66 +/- 6.97 g/mL(1); p < 0.0001) as well. IL-8 and G-CSF levels in BAL fluid correlate only with the percentage and the absolute number of neutrophils of the BAL fluid in patients with PF (p = 0.02/p = 0.01; p = 0.01/p = 0.01; respectively). A significant correlation was found between GM-CSF BAL fluid level and the percentage and the absolute number of the BAL fluid eosinophils (p = 0.04 and p = 0.03). Neutrophils alveolitis, the presence of eosinophils, and higher concentrations of interleukin-8, G-CSF, and GM-CSF in BAL fluid are associated with the development of fibrosis in sulfur mustard victims.

Changes in markers of epithelial permeability and inflammation in chronic smokers switching to a nonburning tobacco device (Eclipse)

Eclipse, produced by R. J. Reynolds Tobacco Company, is a potential reduced exposure product (PREP) that heats rather than burns tobacco. We hypothesized that switching to Eclipse would result in relative normalization of pulmonary epithelial permeability, airway inflammation, and blood leukocyte activation in current smokers. We assessed 10 healthy smokers (aged 21-50 years, 19+/-8 pack-years) at baseline and after 2 and 4 weeks of switching to Eclipse, for symptoms, pulmonary function, airway inflammation, lung clearance of (99m)technicium-diethylenetriaminepentaacetic acid, and blood leukocyte activation and production of reactive oxygen species. Values were compared before and after Eclipse use and with those of healthy, lifetime nonsmokers (aged 18-53 years). Compared with baseline values before switching to Eclipse, lung permeability half-time increased from 33+/-3 to 43+/-6 min (p = .017) after 2 weeks and to 44+/-7 min (p = .10) after 4 weeks of Eclipse use. Carboxyhemoglobin levels increased from 5%+/-2% to 7%+/-2% (p<.01) at 4 weeks. Compared with smoking the usual brand of cigarettes, after smoking Eclipse the percentage of natural killer cells, the expression of intercellular adhesion molecule-1 on monocytes, and the expression of CD45RO on T cells showed significant improvement. However, expression of other surface markers, notably CD23 on monocytes, became more abnormal. Production of reactive oxygen species by smokers' neutrophils and monocytes increased further with Eclipse use. We found no significant effects on pulmonary function, cells in induced sputum, or exhaled nitric oxide. Switching to Eclipse reduces alveolar epithelial injury in some smokers but may increase carboxyhemoglobin levels and oxidative stress.

Aerobic capacity, oxidant stress, and chronic obstructive pulmonary disease--a new take on an old hypothesis

Chronic obstructive pulmonary disease (COPD) is a smoking-related disorder that is a leading cause of death worldwide. It is associated with an accelerated rate of age-related decline in lung function due to the occurrence of destructive pathological changes such as emphysema, small airway remodeling, and mucus hypersecretion. Smokers are exposed to trillions of radicals and thousands of reactive chemicals and particles with every cigarette, thus oxidant stress is believed to be a central factor in the pathogenesis of COPD. The molecular activities of radicals, reactive oxygen, and nitrogen species can, over time, lead to a number of the detrimental changes in the lung. For instance, smoke can directly damage the mitochondrion, an organelle that has long been linked to age-related diseases associated with oxidant stress. Mitochondria are involved in a number of important cellular processes and are the largest source of endogenous reactive oxygen species (ROS) in the cell; therefore, any impairment of mitochondrial function can lead to greater oxidant damage, cellular dysfunction, and eventually to disease. Only a subset of smokers (15-50%) develops COPD, suggesting that there are polygenetic and/or environmental susceptibility factors involved in this complex disease. Here, we propose that the aerobic capacity for an individual may determine whether one is susceptible to developing COPD. Aerobic capacity is a polygenetic trait closely associated with mitochondrial function, and we suggest antioxidant defenses. Thus, those smokers who have the greatest aerobic capacity will be most resistant to the effects of chronic cigarette smoke exposure and be less likely to develop COPD.

Muscarinic receptors, leukotriene B4 production and neutrophilic inflammation in COPD patients

BACKGROUND

Acetylcholine (ACh) plays an important role in smooth muscle contraction and in the development of airway narrowing; preliminary evidences led us to hypothesize that ACh might also play a role in the development of airways inflammation in chronic obstructive pulmonary disease (COPD).

METHODS

We evaluated the concentrations of leukotriene B4 (LTB4) in induced sputum, and the expression of Ach M1, M2, and M3 receptors in sputum cells (SC) obtained from 16 patients with COPD, 11 smokers, and 14 control subjects. The SC were also treated with ACh and the production of LTB4 assessed in the presence or absence of a muscarinic antagonist (oxitropium). In blood monocytes, we evaluated LTB4 release and activation of the extracellular signal-regulated kinases (ERK) pathway after treatment with Ach.

RESULTS

The LTB4 concentrations were higher in COPD than in controls (P < 0.01) and correlated with the number of neutrophil (P < 0.01). The M3 receptors expression was increased in COPD subjects when compared to smokers and control (P < 0.05 and 0.0001, respectively), while M2 expression resulted decreased (P < 0.05 and 0.01). The ACh-induced LTB(4) production was observed in peripheral blood monocytes, and was sensitive to ERK inhibition. Similarly, ACh significantly increased neutrophil chemotactic activity and LTB4 released from SC of COPD patients only, and these effects were blocked by pretreatment with the inhibitor of ERK pathway PD98059.

CONCLUSIONS

The results obtained show that muscarinic receptors may be involved in airway inflammation in COPD subjects through ACh-induced, ERK1/2-dependent LTB4 release. Muscarinic antagonism may contribute to reduce neutrophil infiltration and activation in COPD.

Oxidative stress and lung inflammation in airways disease

Oxidative stress results from an oxidant/antioxidant imbalance in favour of oxidants. A large number of studies have demonstrated that increased oxidative burden occurs in airways diseases, shown by increased marks of oxidative stress in the airspaces and systemically in these patients. There is now substantial evidence that oxidative stress plays an important role in the injurious and inflammatory responses in airways diseases such as asthma and chronic obstructive pulmonary disease (COPD). In addition to these proinflammatory mechanisms resulting from oxidative stress, protective mechanisms such as the upregulation of protective antioxidant genes also occur. At present, effective antioxidant therapy that has good bioavailability and potency is not available. Such drugs are being developed and should in the future allow the hypothesis that oxidative stress is a fundamental factor in the inflammation, which occurs in these airways diseases to be tested.

Protective effects of n-acetylcysteine on lung injury and red blood cell modification induced by carrageenan in the rat

Oxidative stress has been suggested as a potential mechanism in the pathogenesis of lung inflammation. The pharmacological profile of n-acetylcysteine (NAC), a free radical scavenger, was evaluated in an experimental model of lung injury (carrageenan-induced pleurisy). Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained many neutrophils (PMNs), an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate, tumor necrosis factor alpha, and interleukin 1beta. All parameters of inflammation were attenuated by NAC treatment. Furthermore, carrageenan induced an up-regulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS), as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine, and PARS was reduced by NAC. In vivo NAC treatment significantly reduced peroxynitrite formation as measured by the oxidation of the fluorescent dihydrorhodamine-123, prevented the appearance of DNA damage, an decrease in mitochondrial respiration, and partially restored the cellular level of NAD+ in ex vivo macrophages harvested from the pleural cavity of rats subjected to carrageenan-induced pleurisy. A significant alteration in the morphology of red blood cells was observed 24 h after carrageenan administration. NAC treatment has the ability to significantly diminish the red blood cell alteration. Our results clearly demonstrate that NAC treatment exerts a protective effect and clearly indicate that NAC offers a novel therapeutic approach for the management of lung injury where radicals have been postulated to play a role.

Is oxidative stress central to the pathogenesis of chronic obstructive pulmonary disease?

There is now considerable evidence for an increased oxidant burden in patients with chronic obstructive pulmonary disease (COPD). Oxidative stress is a critical feature in the pathogenesis of COPD, since it results in inactivation of antiproteinases, airspace epithelial injury, MUCUS HYPERSECRETION, increased influx of neutrophils into the lungs, transcription factor activation and gene expression of pro-inflammatory mediators. Antioxidants should therefore not only protect against the direct injurious effects of oxidants, but also may fundamentally alter the inflammatory events which have a central role in the pathogenesis of COPD.

Neutrophil deformability in patients with sepsis, septic shock, and adult respiratory distress syndrome

OBJECTIVE

To investigate the deformability of morphologically active and passive neutrophils in patients with sepsis (SP), septic shock (SS), and adult respiratory distress syndrome (ARDS).

DESIGN

Prospective, observational study.

SETTING

A university hospital intensive care unit and research laboratory.

PATIENTS

Six patients with sepsis, six patients with septic shock, and six patients with ARDS. Eight healthy volunteers and eight ventilated but noninfected patients served as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Morphologically passive and active neutrophil deformability as defined by the micropipette method was significantly decreased in patients with SP, SS, and ARDS associated with sepsis as compared with both control groups. Neutrophils from SS and ARDS patients were significantly more rigid as compared with neutrophils from SP patients but they did not differ from each other. The percentage of activated neutrophils was significantly higher in SP, SS, and ARDS patients. Increased passive neutrophil rigidity was significantly attenuated after coincubation with cytochalasin D. Tumor necrosis factor-alpha and interleukin-1beta serum levels were significantly higher in SP, SS, and ARDS patients.

CONCLUSIONS

The entire neutrophil population is less deformable in SP, SS, and ARDS patients. The decreased deformability of passive neutrophils suggests that a direct mechanism involving actin polymerization, distinct from cell activation, is involved. These observations may be important in the mechanism of impaired vascular flow in patients with sepsis.

Comparison of the structural and inflammatory features of COPD and asthma. Giles F. Filley Lecture

At least three conditions contribute to COPD. (1) Chronic bronchitis (mucous hypersecretion) is an inflammatory condition in which CD8+ T-lymphocytes, neutrophils, and CD68+ monocytes/macrophages predominate. The condition is defined clinically by the presence of chronic cough and recurrent increases in bronchial secretions sufficient to cause expectoration. There is enlargement of mucus-secreting glands and goblet cell hyperplasia, which can occur in the absence of airflow limitation. (2) Adult chronic bronchiolitis (small or peripheral airways disease) is an inflammatory condition of small bronchi and bronchioli in which there are predominantly CD8+ and pigmented macrophages. The functional defect is difficult to detect clinically but may be recognized by sophisticated tests of small airway function. There is mucous metaplasia, enlargement of the mass of bronchiolar smooth muscle, and loss of alveolar attachments. (3) Emphysema is an inflammatory condition of the alveoli in which T-lymphocytes, neutrophils, and pigmented alveolar macrophages are involved, associated with the release of excessive amounts of elastases. It is defined anatomically by permanent, destructive enlargement of airspaces distal to terminal bronchioli without obvious fibrosis. In contrast, asthma is a clinical syndrome characterized by allergic inflammation of bronchi and bronchioli in which CD4+ (helper) T-lymphocytes and eosinophils predominate. There is increased production and release of interleukin (IL)-4 and IL-5, which is referred to as a Th2-type response. There is usually increased tracheobronchial responsiveness to a variety of stimuli, and the condition is usually manifest as variable airflow obstruction. While differences between COPD and asthma have been highlighted, new data are emerging that indicate there may also be similarities.

Regulation of ICAM-1 expression in mouse macrophages

In a mouse model of silica (SI) induced lung injury, SI exposure increases expression of intercellular adhesion molecule-1 (ICAM-1) on lung (alveolar/interstitial) macrophages and alveolar type II epithelial cells. To investigate the regulation of SI induced ICAM-1 expression on mouse macrophages, freshly isolated macrophages (alveolar, peritoneal) and macrophage cell lines (MH-S, RAW 264.7) were evaluated for ICAM-1 expression elicited by the particle silica (alpha quartz; 20 microg/ml; 6 microg/cm2) or the inflammatory cytokine, TNFalpha (20 ng/ml). TNFalpha significantly increased ICAM-1 expression in all cell types whereas SI elicited an increase in peritoneal macrophages (PM) and the cell line, MH-S. This pattern of increased expression was confirmed by immunocytochemistry. To investigate the regulation of ICAM-1 expression, PM were incubated with SI, TNFalpha or media concomitantly with anti-TNFalpha antibody, the antioxidant, NAC, or the iNOS synthase inhibitor, L-NAME. Both anti-TNFalpha and NAC, but not L-NAME, inhibited elicited (TNFalpha, SI) as well as constitutive (media) ICAM-1 expression. These data demonstrate that both inflammatory cytokines and inorganic particles can increase ICAM-1 expression on mouse macrophages and that this expression is mediated, in part, by TNFalpha and reactive oxygen species.

Bimodal granulocyte transit time through the human lung demonstrated by deconvolution analysis

The lungs are an important site of granulocyte pooling. The aim of the study is to quantify pulmonary vascular granulocyte transit time using deconvolution analysis, as has previously been performed to measure pulmonary red cell transit time. Granulocyte and red cell studies were performed in separate groups of patients. Both cell types were labelled with Tc-99m, which for granulocyte labelling was complexed with hexamethylpropyleneamine oxime (HMPAO). The red cell impulse response function (IRF) was monoexponential with a median transit time of 4.3 s. The granulocyte IRF was biexponential in 19 of 22 subjects, 18 of whom had systemic inflammation (inflammatory bowel disease, systemic vasculitis or graft-vs-host disease) and four were controls without inflammatory disease. The median transit time of the fast component ranged from 20 to 25 s and of the slow component 120-138 s in the four patient groups. The fraction of cells undergoing slow transit correlated significantly with (a) mean granulocyte transit time and (b) the fraction showing shape change in vitro. We conclude that granulocyte transit time through the pulmonary circulation is bimodal and that shape-changed (activated) cells transit more slowly that non-activated cells. The size of the fraction undergoing slow transit is closely related to mean granulocyte transit time and is an important determinant of the size of the pulmonary vascular granulocyte pool.

The nonspecific inflammatory response to injury

PURPOSE

The role of the nonspecific inflammatory response in causing injury related to surgery has become better understood over the last decade. There are complex interactions between neutrophils, cytokines and nitric oxide metabolites that may cause organ injury following surgery. The purpose of this review is to summarize some of the processes causing injury through these nonspecific pathways.

METHODS

A review of the medical and anaesthetic literature related to inflammation, neutrophils and pro-inflammatory cytokines were performed using Medline. Bibliographies of relevant articles were searched and additional articles were then selected and reviewed.

RESULTS

Pro-inflammatory cytokines, such as tumour necrosis factor, are released in response to a variety of noxious stimuli (e.g. burns, sepsis, or CABG surgery). These cytokines cause activation of neutrophils with increased upregulation of adhesion complexes on neutrophils and vascular endothelium. Nitric oxide synthase activity is also increased with a resultant increased production of nitric oxide. The increased nitric oxide concentration in the presence of superoxide free radicals secreted by activated neutrophils forms peroxynitrite, a more reactive and toxic molecule. Once this process is initiated, diffuse organ injury can result. Although some information related to specific anaesthetics is available, firm recommendations related to clinical practice cannot be made.

CONCLUSIONS

There is a complex interplay of inflammatory mediators that can cause injury. Although specific clinical applications for manipulating these pathways are not yet generally available, this area holds promise to develop new techniques to improve outcomes following surgery.

Depletion of activated neutrophils by a filter during cardiac valve surgery

PURPOSE

To determine whether inclusion of a neutrophil-specific filter into the extracorporeal circuit during open heart valve surgery alters postoperative outcomes.

METHODS

Convenience sampling of 24 patients undergoing elective open heart valve surgery between July 1993 and June 1994. Patients were randomized to a neutrophil-specific filter (n = 11) or to a standard blood filter (n = 13) during cardiopulmonary bypass.

RESULTS

Neutrophil-specific filter diminished (P < 0.02) the expression of CD18, a neutrophil surface adhesion molecule, at I (84.5 +/- 4.2 vs 94.8 +/- 3.8%), 4 (80.0 +/- 4.2 vs 95.1 +/- 3.9%) and 24 hr (75.2 +/- 4.2 vs 98.2 +/- 3.9%) post-operatively compared with standard filter. Total white blood cell count, neutrophil count, and pro-inflammatory cytokines (IL-6, IL-8) were similar between groups at all times. Measured outcomes including: PaO2 cardiac index, ejection fraction, haemodynamic variables, use of inotropes, spirometry (FEV1, FVC), and hospitalization duration were similar between groups.

CONCLUSIONS

Inclusion of the neutrophil filter during open heart valve surgery selectively depletes activated neutrophils. There were no other detectable differences between the two groups and the use of a neutrophil-specific filter in routine clinical practice for patients undergoing open heart valve surgery is not supported.

Anti-CD18 antibodies improve cardiac function following cardiopulmonary bypass in dogs

PURPOSE

Cardiopulmonary bypass is associated with activation of neutrophils, which may adhere to vascular endothelium causing lung, heart, and brain injury. We tested whether blocking neutrophil adherence would improve organ function following cardiopulmonary bypass in dogs.

MATERIALS AND METHODS

All dogs received a standard anesthetic, and then one group (n = 6) received 2 hours of cardiopulmonary bypass followed by 4 hours of observation. A second group (n = 6) received a monoclonal antibody (6 mg/kg) to CD18, a neutrophil adherence factor, immediately before cardiopulmonary bypass. A third group (n = 6) did not receive cardiopulmonary bypass or antibody.

RESULTS

Using flow cytometry we found that the antibody bound essentially all neutrophil CD18 sites. All three groups had similar gas exchange and hemodynamics. Lung and heart histology results were similar between groups. By echocardiography, five animals receiving cardiopulmonary bypass alone showed regional wall abnormalities, whereas only one receiving antibody showed wall motion abnormality (P < .05). Following cardiopulmonary bypass, intracellular myocardial pH was higher (P < .05) in the antibody-treated group compared with the group that had cardiopulmonary bypass alone (7.23 +/- 0.05 v 7.07 +/- 0.07 respectively).

CONCLUSION

Monoclonal antibodies to CD18 can prevent the deterioration in cardiac function routinely observed following cardiopulmonary bypass.

Potential of preventing Pseudomonas aeruginosa lung infections in cystic fibrosis patients: experimental studies in animals

In patients with cystic fibrosis (CF), respiratory tract infections caused by Staphylococcus aureus and Haemophilus influenzae are followed by Pseudomonas aeruginosa with increasing age. Chronic endobronchial lung infection with P. aeruginosa is the leading cause of morbidity and mortality. In Danish CF patients we noted that both onset of initial colonization and chronic lung infection with P. aeruginosa peaked during the winter months which is the season for respiratory virus infections. Virus may therefore pave the way for P. aeruginosa. We established a chronic P. aeruginosa lung infection in rats by embedding mucoid bacteria in seaweed alginate and installing the beads intratracheally into the lower part of the left lung. Although the rats did not suffer from CF, the antibody responses and the pathologic changes of the lungs mimicked the findings in CF patients. By using this model in normal and athymic rats we showed that the T-cell response during the "natural" course of the infection played no major role. In a model of acute P. aeruginosa pneumonia we found that the macroscopic inflammatory response of the lungs was immense and that the natural capacity to clear P. aeruginosa was very efficient and could not be improved by immunization, although high serum levels of IgM, IgG and IgA antibodies to P. aeruginosa alginate, LPS, exotoxin A and sonicate were induced. We developed a method for collecting and measuring IgA in saliva and noted that mucosal IgA antibodies were induced by vaccination; they did not significantly prevent inflammation, however. In the chronic rat model we succeeded to improve the survival significantly and to change the inflammatory response subsequent to vaccination from an acute type inflammation dominated by polymorphonuclear leukocytes (PMNs) as in CF patients to a chronic type inflammation dominated by mononuclear leukocytes. Furthermore, we found that rats immunized with an alginate containing vaccine had a significantly earlier cellular shift to a chronic type inflammation as well as a significant reduction in the severity of the macroscopic inflammation compared to two other vaccine groups and to nonimmunized controls. Similar results were obtained in rats treated with the TH1 cytokine, interferon-gamma (IFN-gamma). Several authors have shown that the lung tissue damage during chronic infection in CF patients is caused by a type III hypersensitivity reaction leading to release of elastase by PMNs surrounding the bacterial microcolonies. The cellular shift we have induced by vaccination and by IFN-gamma treatment therefore offers a possible new strategy for improving the clinical course in chronically infected CF patients.

Effect of soluble P55 tumour-necrosis factor binding fusion protein on the local Shwartzman and Arthus reactions

1. In this study, the effects of a protein synthesis inhibitor, cycloheximide, and a soluble tumour necrosis factor (TNF) binding/IgG fusion protein, p55-sf2, on the priming and challenge stages of the local Shwartzman reaction (LSR) were assessed and compared with their effects on the acute inflammatory response induced by recombinant human tumour necrosis factor-alpha (rhTNF), lipopolysaccharide (LPS) and a reversed passive Arthus (RPA) reaction in rabbit skin. 2. The LSR was induced in skin by giving an intradermal (i.d.) priming injection of LPS followed by two i.v. challenge injections 20 h and 22 h later. Accumulation of 51-Cr-labelled red blood cells and [125I]-albumin were measured at 24 h as markers of haemorrhage and oedema formation, respectively. 3. The RPA reaction was induced in the rabbit by giving i.d. injections of Arthus anti-serum (anti-bovine-gamma-globulin, BGG) followed 5 min later by an i.v. injection of the antigen (BGG). Oedema formation and the accumulation of 111In-labelled neutrophils produced in the RPA reaction and in response to i.d. injection of rhTNF and LPS were measured over the 4 h period after inducing the responses. 4. A single local injection of cycloheximide (10 micrograms/site) did not inhibit neutrophil accumulation or oedema formation produced by 100% Arthus anti-sera. Although LPS injected i.d. induced a marked dose-dependent neutrophil accumulation, there was little associated plasma leakage. Cycloheximide (10 micrograms/site) did not significantly inhibit the neutrophil accumulation induced by LPS (0.1 microgram/site). In the LSR, priming i.d. injections of LPS caused a dose-dependent increase in haemorrhage and plasma leakage at skin sites after challenge with LPS (two injections of 100 micrograms, i.v.). Co-injection of a single dose of cycloheximide (10 micrograms/site) with LPS (30 micrograms/site) caused a marked reduction in the amount of haemorrhage. Local cycloheximide (10 micrograms/site) administered immediately before LSR challenge did not affect the responses produced in the LSR. 5. Neutrophil accumulation induced by TNF (0.17 micrograms/site) was abolished by co-administration of p55-sf2 (3 micrograms/site) whereas neutrophil accumulation induced by i.d. LPS and produced in the RPA reaction was not affected. In the LSR, haemorrhage and oedema formation were inhibited by p55-sf2 (3 micrograms/site) when it was administered i.d. with the LPS priming injection, but not when given i.d. immediately before LSR challenge. 6. These data suggest that the acute neutrophil accumulation produced in the RPA reaction and in response to i.d. LPS may not be dependent on local protein synthesis or TNF production. On the other hand, haemorrhage appears to be dependent on local protein synthesis during the priming phase but not during the challenge stage of the LSR. Importantly, haemorrhage and plasma leakage appear to be dependent on local TNF generation during the priming phase but not during the challenge stage of the LSR. Thus TNF appears to play a key role in the LSR in rabbit skin.

Alteration of neutrophil trafficking by a lipocortin 1 N-terminus peptide

Sialidase, fucoidin and a peptide corresponding to most of lipocortin 1 N-terminus, termed LC1-(Ac2-26)-peptide, induced an intense 2 h neutrophilia whereas a monoclonal antibody to murine CD11b induced an effect by 1 h. The neutropenic response stimulated by platelet-activating factor (PAF) was significantly reduced in the presence of sialidase, fucoidin, LC1-(Ac2-26)-peptide and monoclonal antibody anti-CD11b. Neutrophil migration into a 6-day-old mouse air-pouch induced by interleukin-1 was inhibited by all the pharmacological agents. In vitro, PAF up-regulated CD11b expression on the neutrophil surface but neither human or mouse LC1-(Ac2-26)-peptide inhibited this response. CD11b up-regulation on neutrophils occurred after PAF administration in vivo and was maximal at 2 min. LC1-(Ac2-26)-peptide mimics the action of agents interfering with leucocyte rolling and adhesion in vivo, however, does not inhibit CD11b up-regulation in vitro suggesting other phenomena are important in the activity of this peptide.

Neutrophil sequestration in rat lungs

BACKGROUND

The transit of neutrophils through the pulmonary microvasculature is prolonged compared with red blood cells and is increased further during cigarette smoking and in exacerbations of chronic obstructive pulmonary disease. The increased residence time (sequestration) of neutrophils in the pulmonary capillaries in these conditions may be the first step leading to the accumulation of cells within the lung interstitium and in the bronchoalveolar space, so potentiating lung damage. A rat model has been developed to investigate the factors which may influence neutrophil transit through the lung microvasculature.

METHODS

Intratracheal instillation of the heat killed organism Corynebacterium parvum was used to induce an acute neutrophil alveolitis. Neutrophils and red blood cells were isolated from donor rats, labelled with two distinct radioisotopes, and then reinjected into recipient rats to assess their transit through the pulmonary circulation. To ascertain whether peripheral blood neutrophils were minimally altered by the isolation procedure their functional status in vitro was compared with that of inflammatory neutrophils in a number of assays commonly used as descriptors of neutrophil activation. The influence of neutrophil activation on the accumulation of cells in the lungs was assessed by comparing the lung sequestration of control neutrophils, isolated from peripheral blood, with that of inflammatory neutrophils obtained from bronchoalveolar lavage of inflamed rat lungs. Lung sequestration of neutrophils was defined as the fold increase in the ratio of neutrophils labelled with chromium-51 to red blood cells labelled with technetium-99m in lung tissue compared with the same ratio in peripheral blood.

RESULTS

Sequestration of peripheral blood neutrophils occurred in control rat lungs as shown by a 17.5 (2.1) fold increase in the ratio of neutrophils to red blood cells in the pulmonary circulation compared with the ratio of these cells in the peripheral circulation. When inflammatory neutrophils, obtained by bronchoalveolar lavage from C parvum-treated animals, were injected into control rats, the increase was 90.6 (11.0) fold. Induction of an inflammatory response in the lung tissue of the recipient rat also caused an increase in the sequestration of control neutrophils compared with the same cells in control rat lungs which was, however, less marked than when inflammatory neutrophils were used (34.7 (4.7) fold). The mean (SE) pressure developed on filtration of inflammatory neutrophils in vitro through a millipore filter (7.53 (0.2) cm H2O) was greater than that of peripheral blood neutrophils (1.18 (0.2) cm H2O). Increased filtration pressure indicates a decrease in cell deformability and suggests that this may be a contributory factor to the increased sequestration of inflammatory neutrophils in the pulmonary vasculature.

CONCLUSIONS

This study shows that there is sequestration of neutrophils in the pulmonary vasculature in normal rat lungs which increases in acute lung inflammation and when inflammatory neutrophils are injected into control animals. In this model changes in the neutrophil, such as cell deformability, may have a more important role in inducing increased neutrophil sequestration than the inflammatory response in the lungs.

Particulate air pollution and acute health effects

Epidemiological studies have consistently shown an association between particulate air pollution and not only exacerbations of illness in people with respiratory disease but also rises in the numbers of deaths from cardiovascular and respiratory disease among older people. Meta-analyses of these studies indicate that the associations are unlikely to be explained by any confounder, and suggest that they represent cause and effect. We propose that the explanation lies in the nature of the urban particulate cloud, which may contain up to 100000 nanometer-sized particles per mL, in what may be a gravimetric concentration of only 100-200 micrograms/m3 of pollutant. We suggest that such ultra-fine particles are able to provoke alveolar inflammation, with release of mediators capable, in susceptible individuals, of causing exacerbations of lung disease and of increasing blood coagulability, thus also explaining the observed increases in cardiovascular deaths associated with urban pollution episodes. This hypothesis is testable both experimentally and epidemiologically.

Adhesion molecules in lung diseases

The human body possesses highly specialized cellular defense mechanisms that, when activated pathologically, can induce a number of immunologic disorders. For a normal cellular immune response, the following conditions must be fulfilled: (1) accumulation of white blood cells, (2) their diapedesis through the vessel walls of the inflammatory area affected by an injurious agent, and (3) normal cellular effector functions in the tissue. This cascade of inflammatory processes has recently been shown to be regulated by a group of molecules that are termed adhesion molecules and consist of three subfamilies: selectins, the immunoglobulin supergene family, and integrins. The cellular functions influenced by adhesion molecules include, among others, cytotoxic T-cell responses, CD4-dependent activation of B lymphocytes by T lymphocytes, activation of granulocytes and macrophages, phagocytosis of opsonized particles by monocytes, macrophages, and granulocytes, antigen-presenting function of macrophages, their antibody-dependent cytotoxicity, initiation of a respiratory burst by white blood cells, and activation of fibroblasts. Studies performed in recent years have shown that pathogenetically relevant changes in the expression and function of adhesion molecules are involved in a variety of pulmonary diseases. These changes include the accumulation and activation of alveolar macrophages in smokers, experimentally induced bronchial hyperreactivity in bronchial asthma, accumulation of eosinophils in allergic rhinitis, bleomycin-induced pulmonary fibrosis, binding of viruses and bacteria to respiratory mucosa, and various mechanisms of acute damage to pulmonary parenchyma. Though their role in tumor development is still unclear, adhesion molecules are obviously involved in determining the route and organotropism of metastases. Further studies of the function of adhesion molecules in pulmonary diseases will contribute to our understanding of the pathomechanisms of these diseases and, through the development of specific antibodies, may provide attractive new therapeutic approaches to problems for which treatment is not yet available.

Decreased leukocyte deformability after acute cigarette smoking in humans

Acute cigarette smoking increases the sequestration of neutrophils in the lungs of humans. This may be due to the delayed transit of cells in the pulmonary microcirculation, which may result from a reduction in cell deformability as suggested by in vitro studies of smoke-exposed neutrophils. In order to support this hypothesis we wished to determine if a reduction in leukocyte deformability could be measured in whole blood exposed to smoke in vitro or in vivo. Whole blood filterability, which largely reflects leukocyte deformability, was measured as the pressure developed by filtration of diluted whole blood through a micropore membrane. Whole blood filtration pressures did not change when blood was exposed to smoke in vitro or in venous blood after acute smoking in vivo. However, arterial blood sampled from chronic smokers during acute smoking showed a consistent reduction in leukocyte deformability associated with a small increase in plasma elastase. To assess whether these changes were induced by oxidants in cigarette smoke, we measured the levels of the antioxidant glutathione (GSH), erythrocyte (RBC) membrane fragility, and products of lipid peroxidation in plasma and RBC in blood exposed to smoke in vivo and in vitro. No change in RBC lipid peroxidation or membrane fragility could be detected after in vitro smoke exposure, possibly because of the high antioxidant capacity of the RBC. However, reduced blood GSH levels and increased levels of lipid peroxidation products were detected in plasma, reflecting oxidant stress. In contrast, we were unable to detect evidence of an increased oxidant burden in blood after acute smoking in vivo, in either arterial or venous blood samples.(ABSTRACT TRUNCATED AT 250 WORDS)