Downregulation of IgE antibody and allergic responses in the lung by epidermal biolistic microparticle delivery

Background: Biolistic injections provide a needle-free delivery of antigen-laden microparticles to the epithelium. The precision of the injection preferentially targets the Langerhans cell network, which, although ideal for vaccination, might not be suitable for the downregulation of immune responses in immunotherapy. Objective: We sought to determine the ability of biolistic injection of antigen into the epithelium of sensitized mice to inhibit IgE antibody and lung inflammatory responses produced by further exposure to antigen. Methods: Mice were sensitized by means of a needle injection of ovalbumin (OVA) in alum and given a series of biolistic injections of OVA or vehicle control, followed by a boost of OVA in alum. Serum IgE and IgG antibodies were measured before and after the boost. The mice were then challenged intranasally, and the infiltration of inflammatory cells was measured by means of bronchoalveolar lavage. Airway reactivity of the challenged mice was measured by examining responses to methacholine with forced oscillatory techniques. Results: Biolistic injection of OVA into the dorsal skin of sensitized mice markedly inhibited IgE and IgG1 antibody responses induced by boosting. IgG2a antibody responses were reduced rather than stimulated. The eosinophilic inflammation in the bronchoalveolar lavage fluid induced by intranasal challenge was also markedly inhibited. Lung hyperreactivity showed an initial increase and then a decrease of responsiveness to methacholine, with elastance returning to the level of unsensitized mice. Biolistic injection into the buccal epithelium was also inhibitory. Conclusions: Biolistic injection of allergen inhibited the boosting of IgE antibody and eosinophilic lung inflammatory responses without inducing TO immunity.

Secretoneurin is released into human airways by topical histamine but not capsaicin

Background: The neuropeptide secretoneurin, with potential relevance to leukocyte trafficking, is present in nerves of the nasal mucosa in allergic rhinitis and may be released in response to allergen and histamine exposure. There is no information on the occurrence and mechanisms of release of secretoneurin in healthy human airways. Methods: The presence of secretoneurin in nasal biopsies and its release in response to nasal capsaicin and histamine challenges were examined. Symptoms and lavage fluid levels of fucose were recorded as markers of effects in part produced by neural activity. Bronchial histamine challenges followed by sputum induction and analysis of secretoneurin were also carried out. Results: Nerves displaying secretoneurin immunoreactivity abounded in the nasal mucosa. Nasal capsaicin challenge produced local pain (P < 0.05) and increased the levels of fucose (P < 0.05), but failed to affect the levels of secretoneurin. Nasal histamine challenge produced symptoms (P < 0.05) and increased the mucosal output of secretoneurin (P < 0.05) and fucose (P < 0.05). Bronchial histamine challenge increased the sputum levels of secretoneurin (P < 0.05). Conclusions: We conclude that secretoneurin is present in healthy human airways and that histamine evokes its release in both nasal and bronchial mucosae. The present observations support the possibility that secretoneurin is involved in histamine-dependent responses of the human airway mucosa.

S100A8 chemotactic protein is abundantly increased, but only a minor contributor to LPS-induced, steroid resistant neutrophilic lung inflammation in vivo

Neutrophilic lung inflammation is an essential component of host defense against diverse eukaryotic and prokaryotic pathogens, but in chronic inflammatory lung diseases, such as chronic obstructive lung disease (COPD), severe asthma, cystic fibrosis, and bronchiolitis, it may damage the host. Glucocorticosteroids are widely used in these conditions and in their infectious exacerbations; however, the clinical efficacy of steroids is disputed. In this study, we used a proteomic approach to identify molecules contributing to neutrophilic inflammation induced by transnasal administration of lipopolysaccharide (LPS) that were also resistant to the potent glucocorticosteroid dexamethasone (Dex). We confirmed that Dex was biologically active at both the transcript (suppression of GM-CSF and TNFalpha transcripts) and protein levels (induction of lipocortin) and used 2D-PAGE/MALDI-TOF to generate global expression profiles, identifying six LPS-induced proteins that were Dex resistant. Of these, S100A8, a candidate neutrophil chemotactic factor, was profiled in detail. Steroid refractory S100A8 expression was highly abundant, transcriptionally regulated, secreted into lung lavage fluid and immunohistochemically localized to tissue infiltrating neutrophils. However, in marked contrast to other vascular beds, neutralizing antibodies to S100A8 had only a weak anti-neutrophil recruitment effect and antibodies against the related S100A9 were ineffective. These data highlight the need for extensive in vivo profiling of proteomically identified candidate molecules and demonstrates that S100A8, despite its abundance, resistance to steroids and known chemotactic activity, is unlikely to be an important determinant of LPS-induced neutrophilic lung inflammation in vivo.

Chronic rhinosinusitis and eosinophils: do macrolides have an effect?

Purpose of review: Long-term, low-dose macrolide therapy is effective in the treatment of chronic airway inflammation. It is believed that macrolide antibiotics produce this benefit through an antiinflammatory effect that is separate from their antibiotic effect. Eosinophils are key mediators in the inflammation seen in chronic rhinosinusitis. This review discusses the effect of macrolides on eosinophilic inflammation. Recent findings: In vitro studies recently have suggested that macrolides increase eosinophil apoptosis and reduce production of eosinophil chemotactic cytokines and adhesion molecules. In vivo studies have shown a reduction in eosinophil count and activity in asthma and chronic rhinosinusitis. Clinical response to macrolide treatment is thought to be less likely in patients with atopy. Summary: In contrast to the evidence supporting the effect of macrolides on neutrophilic inflammation, there are limited data to suggest an influence on eosinophilic inflammation. For this reason, patients with prominent eosinophilic inflammation may in the future be identified as being less likely to respond to treatment. Further in vitro and clinical studies are required to investigate this subject.

T1/ST2 - an IL-1 receptor-like modulator of immune responses

Th2-associated factors such as IL-4 are involved in both the development of Th2 responses (via modulating Th2 cell differentiation) and in the effector phase of Th2 responses (via modulating macrophage activation). The IL-1 receptor-like protein ST2 (T1, Fit-1, or DER4) is expressed as a membrane-bound (ST2L) or secreted form (sST2), and has been clearly implicated as a regulator of both the development and effector phases of Th2-type responses. Here we analyze the mechanisms and therapeutic implications of the unique ability of ST2 to promote development and function of type 2 helper T cells through a positive feedback loop, as well as to act as a negative feedback modulator of macrophage pro-inflammatory function. (C) 2004 Elsevier Ltd. All rights reserved.

Sub-inhibitory concentrations of ceftazidime and tobramycin reduce the quorum sensing signals of Pseudomonas aeruginosa

Aim: Concentrations of antimicrobials below minimum inhibitory concentration (subMIC) may reduce the production by Pseudomonas aeruginosa of virulence factors such as elastase. We sought to determine whether the reduction in elastase production may be mediated by a reduction in acyl-homoserine lactones. Methods: Pseudomonas aeruginosa in broth was exposed to three conditions for ceftazidime and tobramycin: control, 6% MIC and 25% MIC. Elastase was assayed using elastin congo red. N-(3-Oxododecanoyl)-homoserine lactone (C12-HSL) and N-butyryl-homoserine lactone (C4-HSL) were assayed using biosensor Escherichia coli. Results: Elastase was unchanged with ceftazidime. Elastase was reduced by 16% at 6% MIC tobramycin and reduced by 70% at 25% MIC tobramycin (P

A double-blind, randomized, placebo-controlled trial of macrolide in the treatment of chronic rhinosinusitis

Objectives: The antiinflammatory effect of macrolide antibiotics has been well-established, as has their role in the treatment of certain disorders of chronic airway inflammation. Several studies have suggested that long-term, low-dose macrolides may be efficacious in the treatment of chronic rhinosinusitis; however, these studies have lacked a control group. To date, this effect has not been tested in a randomized, placebo-controlled study. Method: The authors conducted a double-blind, randomized, placebo-controlled clinical trial on 64 patients with chronic rhinosinusitis. Subjects received either 150 mg roxithromycin daily for 3 months or placebo. Outcome measures included the Sinonasal Outcome Test-20 (SNOT-20), measurements of peak nasal inspiratory flow, saccharine transit time, olfactory function, nasal endoscopic scoring, and nasal lavage assays for interleukin-8, fucose, and a2-macroglobulin. Results. There were statistically significant improvements in SNOT-20 score, nasal endoscopy, saccharine transit time, and IL-8 levels in lavage fluid (P < .05) in the macrolide group. A correlation was noted between improved outcome measures and low IgE levels. No significant improvements were noted for olfactory function, peak nasal inspiratory flow, or lavage levels for fucose and a2-macroglobulin. No improvement in any outcome was noted in the placebo-treated patients. Conclusion: These findings suggest that macrolides may have a beneficial role in the treatment of chronic rhinosinusitis, particularly in patients with low levels of IgE, and supports the in vitro evidence of their antiinflammatory activity. Additional studies are required to assess their place in clinical practice.

Control of ion transport in mammalian airways by protease activated receptors type 2 (PAR-2)

Protease-activated receptors (PARs) are widely distributed in human airways. They couple to G-proteins and are activated after proteolytic cleavage of the N terminus of the receptor. Evidence is growing that PAR subtype 2 plays a pivotal role in inflammatory airway diseases, such as allergic asthma or bronchitis. However, nothing is known about the effects of PAR-2 on electrolyte transport in the native airways. PAR-2 is expressed in airway epithelial cells, where they are activated by mast cell tryptase, neutrophil proteinase 3, or trypsin. Recent studies produced conflicting results about the functional consequence of PAR-2 stimulation. Here we report that stimulation of PAR-2 receptors in mouse and human airways leads to a change in electrolyte transport and a shift from absorption to secretion. Although PAR-2 appears to be expressed on both sides of the epithelium, only basolateral stimulation results in inhibition of amiloride sensitive Na+ conductance and stimulation of both luminal Cl- channels and basolateral K+ channels. The present data indicate that these changes occur through activation of phospholipase C and increase in intracellular Ca2+, which activates basolateral SK4 K+ channels and luminal Ca2+-dependent Cl- channels. In addition, the present data suggest a PAR-2 mediated release of prostaglandin E2, which may contribute to the secretory response. In conclusion, these results provide further evidence for a role of PAR-2 in inflammatory airway disease: stimulation of these receptors may cause accumulation of airway surface liquid, which, however, may help to flush noxious stimuli away from the affected airways. ©2005 FASEB

Challenge-induced plasma exudation and mucinous secretion in human airways

Secretion of mucins and exudation of plasma are distinct processes of importance to innate immunity and inflammatory disease. Yet, little is known about their relation in human airways. The objective of the present study was to use the human nasal airway to determine mucinous secretion and plasma exudation in response to common challenge agents and mediators. Ten healthy volunteers were subjected to nasal challenge-lavage procedures. Thus, the nasal mucosa was exposed to increasing doses of histamine (40 and 400 mu g ml(-1)), methacholine (12.5 and 25 mg) and capsaicin (30 and 300 ng ml(-1)). Fucose was selected as a global marker of mucinous secretion and alpha(2)-macroglobulin as an index of exudation of bulk plasma. All challenge agents increased the mucosal output of fucose to about the same level (P < 0.01-0.05). Once significant secretion had been induced the subsequently increased dose of the challenge agent, in the case of histamine and methacholine, failed to further increase the response. Only histamine increased the mucosal output of alpha(2)-macroglobulin (P < 0.01). We conclude that prompt but potentially rapidly depleted mucinous secretion is common to different kinds of airway challenges, whereas inflammatory histamine-type mediators are required to produce plasma exudation. Along with the acknowledged secretion of mucins, a practically non-depletable, pluripotent mucosal output of plasma emerges as an important component of the innate immunity of human airways.

Protease-activated receptor-2 peptides activate neurokinin-1 receptors in the mouse isolated trachea

Protective roles for protease-activated receptor-2 (PAR2) in the airways including activation of epithelial chloride (Cl-) secretion are based on the use of presumably PAR(2)-selective peptide agonists. To determine whether PAR(2) peptide-activated Cl- secretion from mouse tracheal epithelium is dependent on PAR(2), changes in ion conductance across the epithelium [short-circuit current (I-SC)] to PAR(2) peptides were measured in Ussing chambers under voltage clamp. In addition, epithelium and endothelium-dependent relaxations to these peptides were measured in two established PAR(2) bioassays, isolated ring segments of mouse trachea and rat thoracic aorta, respectively. Apical application of the PAR(2) peptide SLIGRL caused increases in I-SC, which were inhibited by three structurally different neurokinin receptor-1 (NK1R) antagonists and inhibitors of Cl- channels but not by capsaicin, the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP(8-37), or the nonselective cyclooxygenase inhibitor indomethacin. Only high concentrations of trypsin caused an increase in I-SC but did not affect the responses to SLIGRL. Relaxations to SLIGRL in the trachea and aorta were unaffected by the NK1R antagonist nolpitantium (SR 140333) but were abolished by trypsin desensitization. The rank order of potency for a range of peptides in the trachea I-SC assay was 2-furoyl-LIGRL > SLCGRL > SLIGRL > SLIGRT > LSIGRL compared with 2-furoyl-LIGRL > SLIGRL > SLIGRT > SLCGRL (LSIGRL inactive) in the aorta relaxation assay. In the mouse trachea, PAR(2) peptides activate both epithelial NK1R coupled to Cl- secretion and PAR(2) coupled to prostaglandin E-2-mediated smooth muscle relaxation. Such a potential lack of specificity of these commonly used peptides needs to be considered when roles for PAR(2) in airway function in health and disease are determined.

A Bronchoscopic scoring system for airway secretions - Airway cellularity and microbiological validation

There is currently no validated scoring system for quantification of airway secretions in children. A user friendly, valid scoring system of airway secretions during flexible bronchoscopy (FB) would be useful for comparative purposes in clinical medicine and research. The objective of this study was to validate our bronchoscopic secretion (BS) scoring system by examining the relationship between the amount of secretions seen at bronchoscopy with airway cellularity and microbiology. In 106 children undergoing FIB, the relationship of BS grades with bronchocalveolar lavage (BAL) cellularity and infective state (bacterial and viral infections) were examined using receptor operator curves (ROC). BAL was obtained according to European Respiratory Society guidelines; first lavage for microbiology and second lavage for cellularity Area under the ROC was significant for total cell count (TCC) and neutrophil % but not for lymphocyte %. BS grade significantly related to infection positive state (chi(2)(trend) = 5.85, P = 0,016). The area under the ROC for infection positive state versus BS grade was 0.645, 95% Cl 0.527-0.763. The BS scoring system is a valid method for quantifying airway secretions in children undergoing bronchoscopy The system related well to airway cellularity and neutrophilia, as well as to an airway infective state. However, the system is only complementary to cell counts and cultures and cannot replace these laboratory quantification techniques.