Endotoxin-induced Airway Inflammation Research Articles

IL-1 receptor antagonist reduces endotoxin-induced airway inflammation in healthy volunteers

IL-1 receptor antagonist reduces endotoxin-induced airway inflammation in healthy volunteers

Hemokinin-1 is an important mediator of endotoxin-induced acute airway inflammation in the mouse

ObjectiveHemokinin-1, the newest tachykinin encoded by the preprotachykinin C (Tac4) gene, is predominatly produced by immune cells. Similarly to substance P, it has the greatest affinity to the tachykinin NK1 receptor, but has different binding site and signaling mechanisms. Furthermore, several recent data indicate the existence of a not yet identified own receptor and divergent non-NK1-mediated actions. Since there is no information on its functions in the airways, we investigated its role in endotoxin-induced pulmonary inflammation. MethodsAcute pneumonitis was induced in Tac4 gene-deleted (Tac4−/−) mice compared to C57Bl/6 wildtypes by intranasal E. coli lipopolysaccharide (LPS). Airway responsiveness to inhaled carbachol was measured with unrestrained whole body plethysmography 24h later. Semiquantitative histopathological scoring was performed; reactive oxygen species (ROS) production was measured with luminol bioluminescence, myeloperoxidase activity with spectrophotometry, and inflammatory cytokines with Luminex. ResultsAll inflammatory parameters, such as histopathological alterations (perivascular edema, neutrophil/macrophage accumulation, goblet cell hyperplasia), myeloperoxidase activity, ROS production, as well as interleukin-1beta, interleukin-6, tumor necrosis factor alpha, monocyte chemoattractant protein-1 and keratinocyte chemoattractant concentrations were significantly diminished in the lung of Tac4−/− mice. However, bronchial hyperreactivity similarly developed in both groups. Interestingly, in LPS-treated Tac4−/− mouse lungs, bronchus-associated, large, follicle-like lymphoid structures developed. ConclusionsWe provide the first evidence that hemokinin-1 plays a crucial pro-inflammatory role in the lung by increasing inflammatory cell activities, and might also be a specific regulator of lymphocyte functions.

IL-1 receptor antagonist reduces endotoxin-induced airway inflammation in healthy volunteers

Asthma with neutrophil predominance is challenging to treat with corticosteroids. Novel treatment options for asthma include those that target innate immune activity. Recent literature has indicated a significant role for IL-1β in both acute and chronic neutrophilic asthma. This study used inhaled endotoxin (LPS) challenge as a model of innate immune activation to (1) assess the safety of the IL-1 receptor antagonist anakinra in conjunction with inhaled LPS and (2) to test the hypothesis that IL-1 blockade will suppress the acute neutrophil response to challenge with inhaled LPS. In a phase I clinical study 17 healthy volunteers completed a double-blind, placebo-controlled crossover study in which they received 2 daily subcutaneous doses of 1 mg/kg anakinra (maximum dose, 100 mg) or saline (placebo). One hour after the second treatment dose, subjects underwent an inhaled LPS challenge. Induced sputum was assessed for neutrophils 4 hours after inhaled LPS. The effect of anakinra compared with placebo on airway neutrophil counts and airway proinflammatory cytokine levels after LPS challenge was compared by using a linear mixed-model approach. Anakinra pretreatment significantly diminished airway neutrophilia compared with placebo. LPS-induced IL-1β, IL-6, and IL-8 levels were significantly reduced during the anakinra treatment period compared with those seen after placebo. Subjects tolerated the anakinra treatment well without an increased frequency of infections attributable to anakinra treatment. Anakinra effectively reduced airway neutrophilic inflammation and resulted in no serious adverse events in a model of inhaled LPS challenge. Anakinra is a potential therapeutic candidate for treatment of asthma with neutrophil predominance in diseased populations.

Biochemical and cellular correlates of embelin against bacterial endotoxin induced airway inflammation

Biochemical and cellular correlates of embelin against bacterial endotoxin induced airway inflammation

PACAP is an Endogenous Protective Factor—Insights from PACAP-Deficient Mice

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a widespread neuropeptide with a diverse array of biological functions. Not surprisingly, the lack of endogenous PACAP therefore results in a variety of abnormalities. One of the important effects of PACAP is its neuroprotective and general cytoprotective role. PACAP protects neurons and other tissues against ischemic, toxic, and traumatic lesions. Data obtained from PACAP-deficient mice provide evidence that endogenous PACAP also has protective functions. Mice lacking PACAP are more vulnerable to different in vitro and in vivo insults. The present review summarizes data on the increased sensitivity of PACAP-deficient mice against harmful stimuli. Mice lacking PACAP respond with a higher degree of injury in cerebral ischemia, autoimmune encephalomyelitis, and axonal lesion. Retinal ischemic and excitotoxic injuries also produce increased cell loss in PACAP-deficient mice. In peripheral organs, kidney cell cultures from PACAP-deficient mice are more sensitive to oxidative stress and in vitro hypoxia. In vivo, PACAP-deficient mice have a negative histological outcome and altered cytokine response in kidney and small intestine ischemia/reperfusion injury. Large intestinal inflammation, toxic lesion of the pancreas, and doxorubicin-induced cardiomyopathy are also more severe with a lack of endogenous PACAP. Finally, an increased inflammatory response has been described in subacute endotoxin-induced airway inflammation and in an oxazolone-induced allergic contact dermatitis model. In summary, lack of endogenous PACAP leads to higher vulnerability in a number of injuries in the nervous system and peripheral organs, supporting the hypothesis that PACAP is part of the endogenous cytoprotective machinery.

Pituitary adenylate cyclase-activating polypeptide plays an anti-inflammatory role in endotoxin-induced airway inflammation: In vivo study with gene-deleted mice

The presence of pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors in capsaicin-sensitive peptidergic sensory nerves, inflammatory and immune cells suggest its involvement in inflammation. However, data on its role in different inflammatory processes are contradictory and there is little known about its functions in the airways. Therefore, our aim was to examine intranasal endotoxin-induced subacute airway inflammation in PACAP gene-deficient (PACAP−/−) and wild-type (PACAP+/+) mice. Airway responsiveness to inhaled carbachol was determined in unrestrained mice with whole body plethysmography 6h and 24h after LPS. Myeloperoxidase (MPO) activity referring to the number of accumulated neutrophils and macrophages was measured with spectrophotometry and interleukin-1β (IL-1β) concentration with ELISA from the lung homogenates. Histological evaluation and semiquantitative scoring were also performed. Bronchial responsiveness, as well as IL-1β concentration and MPO activity markedly increased at both timepoints. Perivascular edema dominated the histological picture at 6h, while remarkable peribronchial granulocyte accumulation, macrophage infiltration and goblet cell hyperplasia were seen at 24h. In PACAP−/− mice, airway hyperreactivity was significantly higher 24h after LPS and inflammatory histopathological changes were more severe at both timepoints. MPO increase was almost double in PACAP−/− mice compared to the wild-types at 6h. In contrast, there was no difference between the IL-1β concentrations of the PACAP+/+ and PACAP−/− mice. These results provide evidence for a protective role for PACAP in endotoxin-induced airway inflammation and hyperreactivity.

Nicotinamide enhances apoptosis of G(M)-CSF-treated neutrophils and attenuates endotoxin-induced airway inflammation in mice

Neutrophils constitute the first line of host defense against invading microorganisms. Yet their removal from the inflammatory environment is fundamental for injury restraint and resolution of inflammation. Nicotinamide, a component of vitamin B(3), is known to modulate cell survival. In this study, we assessed the influence of nicotinamide on neutrophil apoptosis, both in vitro and in vivo in a mouse model of endotoxin-induced lung inflammation. In vitro, nicotinamide promoted apoptosis of human blood neutrophils in a dose-dependent manner in the presence of the apoptosis inhibitors granulocyte colony-stimulating factor and granulocyte/macrophage colony-stimulating factor. The highest concentration of nicotinamide completely neutralized the pro-survival effect of granulocyte (macrophage) colony-stimulating factor. Nicotinamide proapoptotic effect was associated with enhanced caspase-3 activity. In addition, nicotinamide slightly reduced neutrophil chemotaxis in vitro. In vivo, pulmonary nicotinamide delivery decreased the levels of cellular and biochemical inflammation markers and increased the percentage of apoptotic neutrophils in bronchoalveolar lavages. Our findings suggest that nicotinamide is an apoptotic stimulus for neutrophils, thereby contributing to the resolution of neutrophilic inflammation in the lungs.

Involvement of preprotachykinin A gene-encoded peptides and the neurokinin 1 receptor in endotoxin-induced murine airway inflammation

Tachykinins encoded by the preprotachykinin A (TAC1) gene such as substance P (SP) and neurokinin A (NKA) are involved in neurogenic inflammatory processes via predominantly neurokinins 1 and 2 (NK1 and NK2) receptor activation, respectively. Endokinins and hemokinins encoded by the TAC4 gene also have remarkable selectivity and potency for the NK1 receptors and might participate in inflammatory cell functions. The aim of the present study was to investigate endotoxin-induced airway inflammation and consequent bronchial hyper-reactivity in TAC1(-/-), NK1(-/-) and also in double knockout (TAC1(-/-)/NK1(-/-)) mice. Sub-acute interstitial lung inflammation was evoked by intranasal Escherichia coli lipopolysaccharide (LPS) in the knockout mice and their wildtype C57BL/6 counterparts 24 h before measurement. Respiratory parameters were measured with unrestrained whole body plethysmography. Bronchoconstriction was induced by inhalation of the muscarinic receptor agonist carbachol and Penh (enhanced pause) correlating with airway resistance was calculated. Lung interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) concentrations were measured with ELISA. Histological evaluation was performed and a composite morphological score was determined. Myeloperoxidase (MPO) activity in the lung was measured with spectrophotometry to quantify the number of infiltrating neutrophils/macrophages. Airway hyper-reactivity was significantly reduced in the TAC1(-/-) as well as the TAC1(-/-)/NK1(-/-) groups. However, LPS-induced histological inflammatory changes (perivascular/peribronchial oedema, neutrophil infiltration and goblet cell hyperplasia), MPO activity and TNF-alpha concentration were markedly diminished only in TAC1(-/-) mice. Interestingly, the concentrations of both cytokines, IL-1beta and TNF-alpha, were significantly greater in the NK1(-/-) group. These data clearly demonstrated on the basis of histology, MPO and cytokine measurements that TAC1 gene-derived tachykinins, SP and NKA, play a significant role in the development of endotoxin-induced murine airway inflammation, but not solely via NK1 receptor activation. However, in inflammatory bronchial hyper-responsiveness other tachykinins, such as hemokinin-1 acting through NK1 receptors also might be involved.

Mycobacterial Phosphatidylinositol Mannosides Negatively Regulate Host Toll-like Receptor 4, MyD88-dependent Proinflammatory Cytokines, and TRIF-dependent Co-stimulatory Molecule Expression

Mycobacterium tuberculosis modulates host immune responses through proteins and complex glycolipids. Here, we report that the glycosylphosphatidylinositol anchor phosphatidyl-myo-inositol hexamannosides PIM(6) or PIM(2) exert potent anti-inflammatory activities. PIM strongly inhibited the Toll-like receptor (TLR4) and myeloid differentiation protein 88 (MyD88)-mediated release of NO, cytokines, and chemokines, including tumor necrosis factor (TNF), interleukin 12 (IL-12) p40, IL-6, keratinocyte-derived chemokine, and also IL-10 by lipopolysaccharide (LPS)-activated macrophages. This effect was independent of the presence of TLR2. PIM also reduced the LPS-induced MyD88-independent, TIR domain-containing adaptor protein inducing interferon beta (TRIF)-mediated expression of co-stimulatory receptors. PIM inhibited LPS/TLR4-induced NFkappaB translocation. Synthetic PIM(1) and a PIM(2) mimetic recapitulated these in vitro activities and inhibited endotoxin-induced airway inflammation, TNF and keratinocyte-derived chemokine secretion, and neutrophil recruitment in vivo. Mannosyl, two acyl chains, and phosphatidyl residues are essential for PIM anti-inflammatory activity, whereas the inosityl moiety is dispensable. Therefore, PIM exert potent antiinflammatory effects both in vitro and in vivo that may contribute to the strategy developed by mycobacteria for repressing the host innate immunity, and synthetic PIM analogs represent powerful anti-inflammatory leads.

Exhaled nitric oxide in endotoxin-exposed adults: effect modification by smoking and atopy

Objectives:Occupational exposure to endotoxin is associated with non-allergic asthma and other airway inflammatory reactions. Little is known about the role of mucosal nitric oxide (NO) production in endotoxin-induced airway inflammation....

Roflumilast attenuates pulmonary inflammation upon segmental endotoxin challenge in healthy subjects: A randomized placebo-controlled trial

Rationale Roflumilast, an investigational, targeted phosphodiesterase 4 inhibitor, reduces the in vitro and in vivo inflammatory activity of cells such as neutrophils, eosinophils, macrophages, and monocytes. Objectives The aim of this study was to explore the anti-inflammatory properties of roflumilast in a human model of segmental bronchial endotoxin challenge. Methods In a randomized, placebo-controlled, double-blind, single-center parallel-group study, 37 healthy subjects of either sex were treated for 28 days with either oral roflumilast 500 μg once daily or placebo. At day 29, a baseline bronchoalveolar lavage was performed, followed by segmental endotoxin challenge (4 ng/kg) and saline control challenge. After 24 h, bronchoalveolar lavage fluid was sampled from the challenged segments and cells were counted and differentiated. Results After endotoxin challenge, influx of total cells (difference from baseline) in bronchoalveolar lavage of roflumilast-treated subjects was 36% lower than with placebo ( p=0.02). Correspondingly, the influx of neutrophils and eosinophils of roflumilast-treated subjects was 39% ( p=0.02) and 74% ( p=0.01) lower than with placebo, respectively. In contrast, endotoxin-induced influx of monocytes was not different between roflumilast- and placebo-treated subjects. No significant differences existed between the groups pertaining to endotoxin-induced influx of macrophages and lymphocytes. Roflumilast was well tolerated. No unexpected or serious treatment-emergent signs and symptoms were observed. Conclusions Roflumilast attenuated the endotoxin-induced influx of neutrophils and eosinophils into the airways. This study demonstrates the anti-inflammatory properties of roflumilast on bronchoalveolar granulocytes in endotoxin-induced airway inflammation in healthy subjects.

Role of transient receptor potential vanilloid 1 receptors in endotoxin-induced airway inflammation in the mouse

Airways are densely innervated by capsaicin-sensitive sensory neurons expressing transient receptor potential vanilloid 1 (TRPV1) receptors/ion channels, which play an important regulatory role in inflammatory processes via the release of sensory neuropeptides. The aim of the present study was to investigate the role of TRPV1 receptors in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity with functional, morphological, and biochemical techniques using receptor gene-deficient mice. Inflammation was evoked by intranasal administration of Escherichia coli lipopolysaccharide (60 microl, 167 microg/ml) in TRPV1 knockout (TRPV1(-/-)) mice and their wild-type counterparts (TRPV1(+/+)) 24 h before measurement. Airway reactivity was assessed by unrestrained whole body plethysmography, and its quantitative indicator, enhanced pause (Penh), was calculated after inhalation of the bronchoconstrictor carbachol. Histological examination and spectrophotometric myeloperoxidase measurement was performed from the lung. Somatostatin concentration was measured in the lung and plasma with radioimmunoassay. Bronchial hyperreactivity, histological lesions (perivascular/peribronchial edema, neutrophil/macrophage infiltration, goblet cell hyperplasia), and myeloperoxidase activity were significantly greater in TRPV(-/-) mice. Inflammation markedly elevated lung and plasma somatostatin concentrations in TRPV1(+/+) but not TRPV1(-/-) animals. In TRPV1(-/-) mice, exogenous administration of somatostatin-14 (4 x 100 microg/kg ip) diminished inflammation and hyperreactivity. Furthermore, in wild-type mice, antagonizing somatostatin receptors by cyclo-somatostatin (4 x 250 microg/kg ip) increased these parameters. This study provides the first evidence for a novel counterregulatory mechanism during endotoxin-induced airway inflammation, which is mediated by somatostatin released from sensory nerve terminals in response to activation of TRPV1 receptors of the lung. It reaches the systemic circulation and inhibits inflammation and consequent bronchial hyperreactivity.

Role of capsaicin-sensitive afferents and sensory neuropeptides in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity in the mouse

Substance P (SP) and calcitonin gene-related peptide (CGRP) released from capsaicin-sensitive afferents induce neurogenic inflammation via NK 1, NK 2 and CGRP1 receptor activation. This study examines the role of capsaicin-sensitive fibres and sensory neuropeptides in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity with functional, morphological and biochemical techniques in mice. Carbachol-induced bronchoconstriction was measured with whole body plethysmography 24 h after intranasal lipopolysaccharide administration. SP and CGRP were determined with radioimmunoassay, myeloperoxidase activity with spectrophotometry, interleukin-1β with ELISA and histopathological changes with semiquantitative scoring from lung samples. Treatments with resiniferatoxin for selective destruction of capsaicin-sensitive afferents, NK 1 antagonist SR 140333, NK 2 antagonist SR 48968, their combination, or CGRP1 receptor antagonist CGRP(8-37) were performed. Lipopolysaccharide significantly increased lung SP and CGRP concentrations, which was prevented by resiniferatoxin pretreatment. Resiniferatoxin-desensitization markedly enhanced inflammation, but decreased bronchoconstriction. CGRP(8-37) or combination of SR 140333 and SR 48968 diminished neutrophil accumulation, MPO levels and IL-1β production, airway hyperresponsiveness was inhibited only by SR 48968. This is the first evidence that capsaicin-sensitive afferents exert a protective role in endotoxin-induced airway inflammation, but contribute to increased bronchoconstriction. Activation of CGRP1 receptors or NK 1 + NK 2 receptors participate in granulocyte accumulation, but NK 2 receptors play predominant role in enhanced airway resistance.

Inhibition of endotoxin- and antigen-induced airway inflammation by fudosteine, a mucoactive agent

We evaluated the effect of a mucoactive agent (−)-(R)-2-amino-3-(3-hydroxypropylthio) propionic acid (fudosteine), on airway inflammation using endotoxin- and antigen-induced models. Time courses of growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) production, neutrophil migration and goblet cell hyperplasia were examined in endotoxin-induced rat airway inflammation. GRO/CINC-1 in bronchoalveolar lavage fluid (BALF) increased in response to intratracheal instillation of endotoxin and peaked within 4h. Neutrophils in BALF and goblet cells on trachea peaked 24 and 96h after endotoxin instillation, respectively. Fudosteine significantly inhibited increases in GRO/CINC-1 at 10–100mg/kg, and neutrophils and goblet cells at 30 and 100mg/kg. These results suggest that inflammatory events including neutrophil chemoattractant production and neutrophil migration play important roles for goblet cell hyperplasia in endotoxin-induced airway inflammation, and fudosteine inhibits goblet cell hyperplasia by inhibiting GRO/CINC-1 production and/or neutrophil migration. Furthermore, fudosteine (100mg/kg) inhibited ovalbumin-induced eosinophil infiltration into BALF, suggesting it attenuates asthmatic inflammation.

Vitamin E reduces transendothelial migration of neutrophils and prevents lung injury in endotoxin-induced airway inflammation.

We investigated the pharmacologic effects of the antioxidant Vitamin E (alpha-tocopherol [alpha-toc]) in airway inflammation induced by inhaled endotoxin. A preparation of alpha-toc incorporated in liposomes was administered intraperitoneally in mice 1 h after exposure of aerosolized endotoxin. Injection of 50 mg alpha-toc/kg significantly decreased the number of neutrophils in airspaces and prevented lung injury, monitored both as decreased lactate dehydrogenase activity in airways and reduced lung edema when compared with animals treated with plain liposomes. Immunofluorescence staining of lung tissue revealed that treatment with alpha-toc decreased the number of neutrophils in lung interstitium, whereas the number in lung blood vessels and peripheral blood did not differ between mice treated with alpha-toc and control mice. Our results indicate that alpha-toc downmodulates the migration of neutrophils across the endothelial barrier, but in contrast to strong anti-inflammatory drugs such as corticosteroids, without inhibition of transcription factors involved in the early inflammatory response (nuclear factor-kappaB/activator protein-1). Neither was the endotoxin-induced expression of proinflammatory cytokines in lung tissue downregulated. Treatment with a combination of alpha-toc and a suboptimal dose of 0.5 mg/kg dexamethasone enhanced the effect, suggesting that alpha-toc, in combination with low doses of corticosteroids, might be effective for therapeutic treatment of acute lung injury.

Dose-dependent activation of lymphocytes in endotoxin-induced airway inflammation.

Recruitment of neutrophils to lung tissue and airspaces is a hallmark of inflammatory events following inhalation of endotoxins. We studied the role of different lymphocyte subsets in this inflammation, which is assumed to primarily involve the innate immune system. Inhalation of aerosolized Escherichia coli lipopolysaccharide (LPS) in mice induced a dose-dependent increase in neutrophils in bronchoalveolar lavage fluid, reaching a maximum after 12 h at a low dose and after 24 h at a high dose. Profiles of gene expression in lung tissue indicated an early (2 h) and transient onset of proinflammatory cytokines and chemokines by a low dose of LPS, while a high dose caused more delayed and sustained (6 to 12 h) activation. Gamma interferon, interleukin-2 (IL-2), RANTES, and the alpha chain of the IL-2 receptor were not expressed at a low dose, whereas a high dose of LPS induced a strong expression of these genes, indicating a dose-dependent activation of T cells. A similar pattern was observed for IL-17, supporting a contribution of T cells to the neutrophilic inflammation only at high-dose exposure to LPS. The involvement of lymphocytes in the inflammatory response was further studied using mice with functional deficiencies in defined lymphocyte subsets. Both gammadelta T-cell- and B-cell-deficient mice displayed a response similar to that of the corresponding wild-type strains. Selective depletion of NK cells by in vivo administration of the pk136 antibody did not significantly affect the recruitment of neutrophils into airspaces. Thus, neither NK cells, B cells, nor gammadelta T cells appeared to participate in the host response, suggesting that among the lymphocyte subsets, alphabeta T cells are exclusively involved in endotoxin-induced airway inflammation.

Role of macrophage migration inhibitory factor (MIF) in allergic and endotoxin-induced airway inflammation in mice.

Macrophage migration inhibitory factor (MIF) has recently been forwarded as a critical regulator of inflammatory conditions, and it has been hypothesized that MIF may have a role in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Hence, we examined effects of MIF immunoneutralization on the development of allergen-induced eosinophilic inflammation as well as on lipopolysaccharide (LPS)-induced neutrophilic inflammation in lungs of mice. Anti-MIF serum validated with respect to MIF neutralizing capacity or normal rabbit serum (NRS) was administered i.p. repeatedly during allergen aerosol exposure of ovalbumin (OVA)-immunized mice in an established model of allergic asthma, or once before instillation of a minimal dose of LPS into the airways of mice, a tentative model of COPD. Anti-MIF treatment did not affect the induced lung tissue eosinophilia or the cellular composition of bronchoalveolar lavage fluid (BALF) in the asthma model. Likewise, anti-MIF treatment did not affect the LPS-induced neutrophilia in lung tissue, BALF, or blood, nor did it reduce BALF levels of tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-1alpha (MIP-1alpha). The present data suggest that MIF is not critically important for allergen-induced eosinophilic, and LPS-induced neutrophilic responses in lungs of mice. These findings do not support a role of MIF inhibition in the treatment of inflammatory respiratory diseases.

Tachykinins and Airway Function

Tachykinins encoded by the preprotachykinin A (TAC1) gene such as substance P (SP) and neurokinin A (NKA) are involved in neurogenic inflammatory processes via predominantly neurokinins 1 and 2 (NK1 and NK2) receptor activation, respectively. Endokinins and hemokinins encoded by the TAC4 gene also have remarkable selectivity and potency for the NK1 receptors and might participate in inflammatory cell functions. The aim of the present study was to investigate endotoxin-induced airway inflammation and consequent bronchial hyper-reactivity in TAC1−/−, NK1−/− and also in double knockout (TAC1−/−/NK1−/−) mice.Sub-acute interstitial lung inflammation was evoked by intranasal Escherichia coli lipopolysaccharide (LPS) in the knockout mice and their wildtype C57BL/6 counterparts 24 h before measurement. Respiratory parameters were measured with unrestrained whole body plethysmography. Bronchoconstriction was induced by inhalation of the muscarinic receptor agonist carbachol and Penh (enhanced pause) correlating with airway resistance was calculated. Lung interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations were measured with ELISA. Histological evaluation was performed and a composite morphological score was determined. Myeloperoxidase (MPO) activity in the lung was measured with spectrophotometry to quantify the number of infiltrating neutrophils/macrophages.Airway hyper-reactivity was significantly reduced in the TAC1−/− as well as the TAC1−/−/NK1−/− groups. However, LPS-induced histological inflammatory changes (perivascular/peribronchial oedema, neutrophil infiltration and goblet cell hyperplasia), MPO activity and TNF-α concentration were markedly diminished only in TAC1−/− mice. Interestingly, the concentrations of both cytokines, IL-1β and TNF-α, were significantly greater in the NK1−/− group.These data clearly demonstrated on the basis of histology, MPO and cytokine measurements that TAC1 gene-derived tachykinins, SP and NKA, play a significant role in the development of endotoxin-induced murine airway inflammation, but not solely via NK1 receptor activation. However, in inflammatory bronchial hyper-responsiveness other tachykinins, such as hemokinin-1 acting through NK1 receptors also might be involved.

Endotoxin-induced inflammation and injury of the guinea pig respiratory airways cause bronchial hyporeactivity.

It was investigated whether an endotoxin-induced airway inflammation and injury correlated with the induction of bronchial hyperreactivity. Guinea pigs were treated with an endotoxin aerosol, and 4 and 24 h later lung lavages were performed and a differential cell count was made. The number of neutrophils and monocytes was significantly increased (p less than 0.005) at these times. After 24 h, the number of eosinophils and lymphocytes was also increased (p less than 0.005). The number of alveolar macrophages remained unchanged. Histologic examination revealed increased intraluminal mucus and an influx of erythrocytes and neutrophils in the tracheal and bronchial lumen at both time points after the endotoxin aerosol. The epithelium was morphologically changed and contained many neutrophils. Focal matting and/or loss of cilia also occurred. Airway smooth muscle responsiveness was measured in vitro on isolated guinea pig tracheal smooth muscle preparations 4 and 24 h after endotoxin aerosol. No differences in the maximal responses or slope factors of the dose-response curves for carbachol, histamine, or isoprenaline were detected between the control and endotoxin-exposed groups. The EC50 value of the histamine dose-response curve 4 h after endotoxin nebulization was slightly but significantly (p less than 0.05) increased, indicating decreased sensitivity. Responsiveness in vivo was measured in anesthetized spontaneously breathing guinea pigs 24 h after the endotoxin aerosol. The histamine-induced increase in pulmonary resistance was reduced by about 35% in the endotoxin-nebulized group (p less than 0.01). It can be concluded that an influx of inflammatory cells accompanied by injury of the airways induces hyporeactivity of the guinea pig respiratory tract.

On the management of retained airgun pellets: a survey of 11 orbital cases.

Relevant factors determining the management of inaccessible retained lead airgun pellets are discussed in relation to 11 orbital cases. Although the injuries were of between one month's and 26 years' standing, serum lead levels were normal at under 350 micrograms/l in all instances. This is attributable to the modern alloy composition of the ammunition in question. It is concluded that surgical intervention may be indicated only where there is a mechanical disturbance of ocular motility allied with good visual function.