Leukotrienes Are Dispensable for Vaginal Neutrophil Recruitment as Part of the Immunopathological Response During Experimental Vulvovaginal Candidiasis

Recruitment of polymorphonuclear neutrophils (PMNs) into the vaginal lumen is the hallmark of an acute immunopathologic inflammatory response during vulvovaginal candidiasis (VVC) caused by Candida albicans. Recurrent VVC (RVVC) remains a chronic health burden in affected women worldwide despite the use of antifungal therapy. Based on the role leukotrienes (LTs) play in promoting inflammation, leukotriene receptor antagonists (LTRAs) targeted for LTB₄ (etalocib) or LTC₄, LTD_4, and LTE₄ (zafirlukast or montelukast) have been shown to reduce inflammation of epithelial tissues. An open-label pilot study using long-term regimens of zafirlukast in women with RVVC indicated the potential for some relief from recurrent episodes. To investigate this clinical observation further, we evaluated the effects of LT antagonistic agents and LT deficiency on the immunopathogenic response in a mouse model of VVC. Results showed that mice given daily intraperitoneal injections of individual LTRAs, starting 2days prior to vaginal inoculation with C. albicans and continuing through 14days post-inoculation, had no measurable reduction in PMN migration. The LTRAs were also ineffective in reducing levels of the hallmark vaginal inflammatory markers (S100A8, IL-1β) and tissue damage (LDH) associated with the immunopathogenic response. Finally, LT-deficient 5-lipoxygenase knockout mice showed comparable levels of vaginal fungal burden and PMN infiltration to wild-type mice following inoculation with a vaginal (ATCC 96113) or laboratory (SC5314) C. albicans isolate. These results indicate that despite some clinical evidence suggestive of off-target efficacy of LTRAs in RVVC, LTs and associated signaling pathways appear to be dispensable in the immunopathogenesis of VVC.

Resolvin E1, resolvin D1 and resolvin D2 inhibit constriction of rat thoracic aorta and human pulmonary artery induced by the thromboxane mimetic U46619

BACKGROUND AND PURPOSE

The ω-6 fatty acid-derived lipid mediators such as prostanoids, thromboxane and leukotrienes have well-established roles in regulating both inflammation and smooth muscle contractility. Resolvins are derived from ω-3 fatty acids and have important roles in promoting the resolution of inflammation, but their activity on smooth muscle contractility is unknown. We investigated whether resolvin E1 (RvE1), resolvin D1 (RvD1) and resolvin D2 (RvD2) can modulate contractions of isolated segments of rat thoracic aorta (RTA) or human pulmonary artery (HPA) induced by the α₁ -adrenoceptor agonist phenylephrine or the stable thromboxane A₂ mimetic U46619.

EXPERIMENTAL APPROACH

Contractile responses in RTA and HPA were measured using wire myography. Receptor expression was investigated by immunohistochemistry.

KEY RESULTS

Constriction of RTA segments by U46619, but not by phenylephrine, was significantly inhibited by pretreatment for 1 or 24 h with 10-100 nM RvE1, RvD1 or RvD2. The inhibitory effect of RvE1 was partially blocked by a chemerin receptor antagonist (CCX832). RvE1 at only 1-10 nM also significantly inhibited U46619-induced constriction of HPA segments, and the chemerin receptor, GPR32 and FPR2/ALX were identified in HPA smooth muscle.

CONCLUSION AND IMPLICATIONS

These data suggest that resolvins or their mimetics may prove useful novel therapeutics in diseases such as pulmonary arterial hypertension, which are characterized by increased thromboxane contractile activity.

Variation in preparation for gastroscopy: lessons towards safer and better outcomes

OBJECTIVE

To identify the methods employed within the UK practice prior to diagnostic gastroscopy and compare with published guidelines for patients undergoing general anaesthesia.

DESIGN

National Health Service (NHS) endoscopy units were invited to take part in a structured telephone survey to determine the length of time patients are kept nil-by-mouth (NBM) for food and fluids prior to gastroscopy, and whether a preprocedure mucolytic drink was used.

METHODS

212 NHS Trusts providing endoscopy services were identified from the Joint Advisory Group on GI Endoscopy. Trusts were excluded if they were children's hospitals (n=5).

RESULTS

207 NHS Trusts were telephoned. 193 completed the survey (93%), 11 Trusts declined and there was no response from 3 Trusts. 13 separate policies regarding NBM timings were identified. 51 Trusts (21%) used the timings ratified by Surgical and Anaesthetic Societies (6 h NBM for food, 2 h for clear fluid). 135 Trusts (70%) used a policy which starved patients in excess of the standard surgical guidelines. No Trust used a mucolytic drink prior to gastroscopy.

CONCLUSIONS

The survey revealed large variation in NHS Trust's policies regarding the times patients were starved prior to gastroscopy. Results of surgical studies demonstrate increased risk of significant pulmonary aspiration with increased fluid-starvation periods, 68% of NHS endoscopy policy would be deemed excessive by surgical practice. There is no routine use of a mucolytic drink to improve mucosal visualisation in the UK practice.

Abstract 624: Resolvin E1 Inhibits Thromboxane-Induced Contraction of Rat Aorta and Human Pulmonary Artery

Thromboxane is a vasoactive omega-6-derived lipid implicated in hypertension. Omega-3 fatty acid derivatives including resolvin (Rv) E1 have important roles in the resolution of inflammation, but their ability to mediate vasomotor activity is unknown. We assessed whether RvE1 modulates contraction of rat thoracic aorta and human pulmonary artery (HPA) in vitro.

Rats were culled by CO2 inhalation and cervical dislocation, and the thoracic aorta was removed. HPA were obtained with informed consent from lung tissue of surgical patients at Southampton General Hospital. Segments of aorta or HPA were incubated in DMEM-F12 with or without RvE1 (10 nM, 100 nM or 300 nM) for 1 or 24 hours, and then mounted on a wire myograph. Mounted segments were bathed at 37[[Unable to Display Character: ]]C in Kreb’s buffer, gassed (95%/5% O2/CO2) and set to 1.5 g of baseline tension. Functional integrity was confirmed by a contractile response to 125 mM KPSS. After washing to restore baseline tension, a cumulative concentration-response curve was defined to the stable thromboxane A2 mimetic U46619 (1 nM - 1 μM). Contractions are expressed as percent of KPSS response and differences determined by two-way ANOVA and by pairwise comparisons.

In rat aorta, treatment with RvE1 (10 nM) significantly shifted the U46619 curve rightwards, increasing the EC50 value 13-fold from 0.13 μM to 1.75 μM after 1 hour (n=5), and 4-fold from 0.093 μM to 0.41 μM after 24 hours (n=5). In contrast, 300 nM RvE1 caused no significant change in EC50 (1 hour 0.11 μM; 24 hours 0.097 μM, n=5).

In HPA segments, RvE1 (10 nM, 1 hour) increased the U46619 EC50 value 7-fold from 0.0079 μM to 0.054 μM (n=3), with a preliminary experiment suggesting a similar outcome after 24 hours. Higher concentrations of RvE1 had no significant effect, suggesting the relaxant action of RVE1 has a bell-shaped response curve. In preliminary experiments, RvE1 inhibited U-46619 contractions of bronchiolar airways from the same human donors.

Resolvin E1 is known for its immunomodulatory actions on leukocytes and also inhibits U46619-induced aggregation of platelets, but our results are the first evidence that this pro-resolution mediator can also inhibit contractions of intact vasculature from rat and human lung induced by a thromboxane mimetic.

Developments in the field of allergy in 2011 through the eyes of Clinical and Experimental Allergy

As in previous years, we felt it would be of value to our readership to summarize the new information provided by the authors who have published in Clinical and Experimental Allergy in 2011 and set this in the context of recent advances in our understanding of the pathogenesis and management of allergic disease in all its many manifestations. In 2011, about 210 articles were published in Clinical and Experimental Allergy including editorials, reviews, opinion articles, guidelines, letters, book reviews and of course at the heart of the journal, papers containing original data. As before, this review is divided into sections based on the way the journal is structured, although this year we have grouped together all the papers dealing with mechanisms of allergic disease, whether they involve patients (clinical mechanisms), pure in vitro studies (basic mechanisms) or animal models (experimental models), as we felt this was a more coherent way to deal with the subject. In the field of asthma and rhinitis, the relationship between airway inflammation and airway dysfunction was of perennial interest to investigators, as were phenotypes and biomarkers. Aspirin hypersensitivity appeared in studies in several papers and there was new interest in asthma in the elderly. The mechanisms involved in allergic disease describe advances in our understanding of T cell responses, the relationship between inflammation and disease, mast cell and basophil activation, steroid resistance and novel therapies. In the section dealing with epidemiology, studies seeking to identify risk factors for allergic disease including vitamin D are prominent, as once again are studies investigating gene-environment interactions. The clinical allergy section focuses on drug allergy, food allergy and immunotherapy. The area of oral immunotherapy for food allergy is well covered and we were grateful to Stephen Durham for guest editing an outstanding special issue on immunotherapy in the centenary year of Leonard Noon's pioneering work. Lastly, in the field of allergens, the interest in component-resolved diagnosis continues to grow and there are also articles describing important novel cultivars and the effect of food processing on the allergenic properties of foods. Another terrific year, full of important and high-quality work,which the journal has been proud to bring to the allergy community.

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Leukotrienes are bronchoconstrictor and pro-inflammatory mediators implicated in asthma. Drugs that block leukotriene synthesis or activity are set to become the first major breakthrough in asthma therapy for 25 years. Antileukotriene drugs block bronchoconstriction after challenge with allergen, aspirin or exercise, and in clinical trials in patients with asthma they improve baseline lung function, reduce night-time awakenings, improve daytime symptom scores and halve the number of acute exacerbations. They are likely to be used as oral prophylactic therapy to reduce the dosage of corticosteroids right across the spectrum of asthma severity. Further studies on possible long term anti-inflammatory effects are currently in progress.

Increased expression of the 5-lipoxygenase pathway and its cellular localization in Barrett's adenocarcinoma

AIMS

Up-regulation of the 5-lipoxygenase (5-LOX) leukotriene pathway is evident in numerous tumour types, and has been linked to the promotion of cancer cell growth. The aim of this study was to evaluate the immunohistochemical expression of 5-LOX pathway proteins in oesophageal adenocarcinoma and its premalignant lesion, Barrett's metaplasia.

METHODS AND RESULTS

Tissue samples were collected at endoscopy from 16 patients with Barrett's metaplasia and from seven with oesophageal adenocarcinoma; five proximal squamous oesophagus samples were used as controls. Immunohistochemical analyses were performed on stromal and epithelial areas with optimized concentrations of primary antibodies for 5-LOX, 5-LOX-activating protein (FLAP), and the distal enzymes leukotriene (LT) A(4) hydrolase (LTA(4) H) and LTC(4) synthase (LTC(4) S). the diagnosis was histologically confirmed from adjacent sections by a gastrointestinal pathologist. Striking increases in the stromal immunoexpression of 5-LOX (P = 0.041), FLAP (P = 0.038), LTA(4) H (P = 0.0008) and LTC(4) S (P = 0.036) were seen in adenocarcinoma tissue. Stromal FLAP and LTA(4) H immunostaining correlated with elevated neutrophil counts (P < 0.001). LTC(4) S was also notably overexpressed within epithelial cells in both Barrett's metaplasia (P < 0.001) and adenocarcinoma (P < 0.01) tissue.

CONCLUSIONS

Key biosynthetic enzymes of the LTB(4) and LTC(4) biosynthetic pathways are incrementally expressed across the spectrum of squamous, Barrett's metaplasia and oesophageal adenocarcinoma tissues, suggesting, for the first time, a role for both LT subfamilies in disease progression.

FLAP inhibitors for the treatment of inflammatory diseases

Leukotrienes are lipid inflammatory mediators that are implicated in asthma, COPD, arthritis, cardiovascular disease and cancer. Leukotriene synthesis requires 5-lipoxygenase activating protein (FLAP), which acts as a scaffolding protein for the assembly of other enzymes involved in the leukotriene synthetic pathway occurring at the nuclear envelope of leukocytes. By blocking the formation of both leukotriene B4 and the cysteinyl leukotrienes (ie, LTC4 , LTD4 and LTE4), FLAP inhibitors act as broad-spectrum leukotriene-modifier drugs that may have a wide range of therapeutic applications. FLAP inhibitors such as MK-886, MK-0591 and veliflapon (BAY-X-1005, DG-031) demonstrated promise in clinical trials with patients with inflammatory diseases in the mid 1990 s, but, unlike the 'lukast' class of cysteinyl-leukotriene receptor antagonists, these compounds were not brought to market. The elucidation of the 3D structure of FLAP has enabled novel compound development, and several FLAP inhibitors including 2190914 (AM-103) and GSK-2190915 (both under development by GlaxoSmithKline plc) have entered phase II trials for the treatment of inflammatory disease, including asthma.

Nasal mucosal expression of the leukotriene and prostanoid pathways in seasonal and perennial allergic rhinitis

BACKGROUND

Leukotrienes (LTs) and prostanoids are potent pro-inflammatory and vasoactive lipid mediators implicated in airway disease, but their cellular sources in the nasal airway in naturally occurring allergic rhinitis (AR) are unclear.

OBJECTIVE

To quantify cellular expression of enzymes of the 5-lipoxygenase (5-LO) and cyclooxygenase (COX) pathways by immunohistochemistry in nasal biopsies from patients with symptomatic perennial AR (PAR, n = 13) and seasonal AR (SAR, n = 14) and from normal subjects (n = 12).

METHODS

Enzymes of the 5-LO pathway (5-LO, FLAP, LT A4 hydrolase, LTC4 synthase) and the COX pathway (COX-1, COX-2, prostaglandin D2 synthase) were immunostained in glycol methacrylate resin-embedded inferior turbinate biopsy specimens, quantified in the lamina propria and epithelium, and co-localized to leucocyte markers by camera lucida.

RESULTS

In the lamina propria of PAR biopsies, median counts of cells expressing FLAP were fourfold higher than in normal biopsies (Mann-Whitney, P = 0.014), and also tended to be higher than in SAR biopsies (P = 0.06), which were not different from normal. PAR biopsies showed threefold more cells immunostaining for LTC4 synthase compared with SAR biopsies (P = 0.011) but this was not significant compared with normal biopsies (P = 0.2). These changes were associated with ninefold more eosinophils (P = 0.0005) with no differences in other leucocytes. There were no significant differences in the lamina propria in immunostaining for 5-LO, LTA4 hydrolase, COX-1, COX-2 or PGD2 synthase. Within the epithelium, increased expression of COX-1 was evident in PAR biopsies (P = 0.014) and SAR biopsies (P = 0.037), associated with more intra-epithelial mast cells in both rhinitic groups (P < 0.02).

CONCLUSIONS

In the nasal biopsies of PAR subjects, increased expression of regulatory enzymes of the cysteinyl-LT biosynthetic pathway was associated with lamina propria infiltration by eosinophils. Seasonal rhinitis biopsies shared only some of these changes, consistent with transient disease. Increased intra-epithelial mast cells and epithelial COX-1 expression in both rhinitic groups may generate modulatory prostanoids.

CysLTR1 promoter polymorphism and requirement for leukotriene receptor antagonist in aspirin-intolerant asthma patients

OBJECTIVES

Leukotriene receptor antagonists (LTRA), such as montelukast, have been used as a first-line treatment for patients with aspirin-intolerant asthma (AIA). This study evaluated associations between the clinical requirement for LTRA and genetic polymorphisms of the ALOX5, LTC4S, COX-2, CysLTR1 and TBXA2R genes in the arachidonic acid cascade in the long-term management of 89 AIA patients from a Korean population.

METHODS

Asthma control status was monitored for 1 year with maintenance medications of inhaled corticosteroid and oral LTRA, and AIA patients were classified into three groups according to the mean montelukast dose required per month to maintain asthma control for 1 year: group I (> or = 200 mg montelukast/month; n = 37), group II (5-150 mg/month; n = 25) and group III (< 5 mg/month; n = 27). Genetic polymorphisms in the arachidonic acid cascade were determined using a single-base extension method.

RESULTS

We found that there was a significant difference in the genotype frequency of the CysLTR1 promoter polymorphism -634C > T among the three groups (p = 0.007 for group I vs group II, p = 0.017 for group I vs group III), while there were no significant associations between LTRA requirements and polymorphisms of the other genes. The patients with the variant genotype (CT or TT) of the -634C = T CysLTR1 promoter polymorphism showed a higher expression level than those with the common genotype (CC).

CONCLUSION

These findings indicate that the CysLTR1 promoter polymorphism is a useful genetic marker for predicting LTRA requirements in the long-term management of AIA patients.

Human bronchial epithelial cells express an active and inducible biosynthetic pathway for leukotrienes B4 and C4

BACKGROUND

Human bronchial epithelial cells synthesize cyclooxygenase and 15-lipoxygenase products, but the 5-lipoxygenase (5-LO) pathway that generates the leukotriene (LT) family of bronchoconstrictor and pro-inflammatory mediators is thought to be restricted to leucocytes.

OBJECTIVE

We hypothesized that human bronchial epithelial cells (HBECs) express a complete and active 5-LO pathway for the synthesis of LTB4 and LTC4, either constitutively or after stimulation.

METHODS

Flow cytometry, RT-PCR, Western blotting, enzyme immunoassays and reverse-phase high-performance liquid chromatography were used to investigate constitutive and stimulated expression of 5-LO pathway enzymes and the synthesis of LTs B4 and C4 in primary HBECs and in the 16-HBE 14o- cell line.

RESULTS

Constitutive mRNA and protein expression for 5-LO, 5-LO-activating protein (FLAP), LTA4 hydrolase and LTC4 synthase were demonstrated in primary HBECs and in the 16-HBE 14o- cell line. In 16-HBE 14o- cells, treatment with calcium ionophore A23187, bradykinin or LPS up-regulated the expression of these enzymes. The up-regulation of 5-LO was blocked by the anti-inflammatory glucocorticoid dexamethasone. Human bronchial epithelial cells were shown to generate bioactive LTs, with primary HBECs generating 11-fold more LTC4 and five-fold more LTB4 than 16-HBE 14o- cells. LT production was enhanced by ionophore treatment and blocked by the FLAP inhibitor MK-886.

CONCLUSIONS

Expression of an active and inducible 5-LO pathway in HBEC suggests that damaged or inflamed bronchial epithelium may synthesize LTs that contribute directly to bronchoconstriction and leucocytosis in airway inflammation.

Colonic expression of leukotriene-pathway enzymes in inflammatory bowel diseases

BACKGROUND

Leukotrienes derived from the 5-lipoxygenase pathway are proinflammatory lipid mediators that possibly play a role in inflammatory bowel diseases. The expression of 5-lipoxygenase pathway proteins has not previously been examined in colonic mucosa in inflammatory bowel disease.

RESULTS

Quantitative immunohistochemical analyses showed that, compared to those of the control subjects (n = 9), colonic biopsies from patients with active inflammatory bowel disease (n = 17) had 3- to 7-fold higher mean counts of cells expressing 5-lipoxygenase (P = 0.03), 5-lipoxygenase-activating protein (P = 0.005), and the leukotriene A(4) hydrolase (P = 0.004), which make up the biosynthetic pathway of the potent neutrophil chemotaxin leukotriene B(4). Immunoexpression of the leukotriene C(4) synthase was unaltered (P > 0.2). The increased representation of leukotriene B(4)-pathway enzymes was associated with higher counts of neutrophils (P = 0.0001), macrophages (P = 0.03), eosinophils (P = 0.0004), CD8(+) T cells (P < 0.001), activated T cells (P < 0.05), and B cells (P < 0.05) but not of mast cells (P > 0.9). These eicosanoid and cellular changes were most marked in the subgroup of patients with ulcerative colitis (n = 9), and were absent in patients with quiescent disease (n = 6). The anomalies in the 5-lipoxygenase pathway were accompanied as expected by more cells immunostaining for cytokine-inducible COX-2 (P = 0.004, n = 17), but this study also revealed a greater number of cells expressing COX-1 in the samples from the patients in the ulcerative colitis subgroup (P = 0.03, n = 9).

CONCLUSIONS

The 5-lipoxygenase data provide a cellular basis for increased tissue synthesis of the leukotriene B(4), as reflected in the colonic mucosa and rectal dialysates of patients with active inflammatory bowel disease, which contributes to neutrophil influx and colonic injury. The COX-1/COX-2 data highlight the ambiguous functional role of prostanoid pathways in inflammatory bowel diseases.

Cysteinyl leukotrienes synergize with growth factors to induce proliferation of human bronchial fibroblasts

BACKGROUND

Cysteinyl leukotrienes (cys-LTs) are potent asthma-related mediators that function through their G protein-coupled receptors, cys-LT receptor type 1 (CysLT1R) and cys-LT receptor type 2 (CysLT2R).

OBJECTIVE

Because many G protein-coupled receptors transactivate the epidermal growth factor receptor (EGFR) through metalloprotease-mediated ligand shedding, we investigated the effects of cys-LTs on signal transduction and proliferation of bronchial fibroblasts.

METHODS

Human bronchial fibroblasts were grown from biopsy specimens of healthy subjects. Mitogenesis was assessed on the basis of tritiated methylthymidine incorporation.

RESULTS

Leukotriene (LT) D(4) alone did not increase mitogenesis but dose-dependently increased thymidine incorporation and cell proliferation in the presence of epidermal growth factor (EGF). The enhancement was not prevented by CysLT1R antagonists (MK-571 and montelukast) or by a dual antagonist (BAY u9773), which is consistent with the lack of detectable mRNA for CysLT1R and CysLT2R in bronchial fibroblasts. LTD(4) did not cause EGFR transphosphorylation nor was the synergism blocked by the metalloprotease inhibitor GM6001. The EGFR-selective kinase inhibitor AG1478 suppressed the synergy between LTD(4) and EGF but had no effect on synergistic interactions of LTD(4) with other receptor tyrosine kinase growth factors. The effect of LTD(4) involved a pertussis toxin-sensitive and protein kinase C-mediated intracellular pathway, leading to sustained growth factor-dependent phosphorylation of extracellular signal-regulated kinase 1/2 and protein kinase B (PKB/Akt).

CONCLUSION

Cys-LTs do not transactivate EGFR but have a broader capability to synergize with receptor tyrosine kinase pathways.

CLINICAL IMPLICATIONS

This study implies a critical role of cys-LTs in airway fibrosis in asthma and other chronic airway diseases, which might not be blocked by therapy with current LT receptor antagonists.

The cysteinyl-leukotriene type 1 receptor polymorphism 927T/C is associated with atopy severity but not with asthma

BACKGROUND

The cysteinyl-leukotriene receptor type 1 (CysLT1) mediates the bronchoconstrictor and pro-inflammatory actions of cysteinyl-leukotrienes (LTC4, LTD4, LTE4) in asthma and is the molecular target of the lukast class of oral anti-leukotriene drugs. We screened the CYSLTR1 gene on chromosome Xq13-21 for coding region polymorphisms, and investigated their associations with allergy and asthma.

METHODS

Solid-phase chemical cleavage was used to screen polymorphisms in the coding region of CYSLTR1. A TaqMan allelic discrimination assay was used to genotype a 927T/C SNP and oligonucleotide ligation assays were used to genotype the previously reported 617T/C and 898G/A SNPs of CYSLTR1 in 341 asthmatic families from the UK. Associations with asthma diagnosis, atopic status, serum-specific IgE and severity of allergy and asthma were examined.

RESULTS

Family-based association tests showed that the 927 T allele was associated with atopy severity, especially in female subjects, but not with asthma diagnosis or severity, atopic status, bronchial hyper-responsiveness to methacholine or forced expiratory volume in 1 s.

CONCLUSION

Mutation screening identified only one polymorphism, 927T/C, in the coding region of the CysLT1 receptor. This polymorphsim is predictive of atopy severity, but not associated with asthma.

Expression of 5-lipoxygenase and cyclooxygenase pathway enzymes in nasal polyps of patients with aspirin-intolerant asthma

In aspirin-intolerant subjects, adverse bronchial and nasal reactions to cyclooxygenase (COX) inhibitors are associated with over-production of cysteinyl-leukotrienes (cys-LTs) generated by the 5-lipoxygenase (5-LO) pathway. In the bronchi of patients with aspirin-intolerant asthma, we previously linked cys-LT over-production and aspirin hyper-reactivity with elevated immunoexpression in eosinophils of the terminal enzyme for cys-LT production, LTC4 synthase. We investigated whether this anomaly also occurs in the nasal airways of these patients. Immunohistochemical expression of 5-LO and COX pathway proteins was quantified in nasal polyps from 12 patients with aspirin-intolerant asthma and 13 with aspirin-tolerant asthma. In the mucosa of polyps from aspirin-intolerant asthmatic patients, cells immunopositive for LTC4 synthase were four-fold more numerous than in aspirin-tolerant asthmatic patients (p=0.04). There were also three-fold more cells expressing 5-LO (p=0.037), with no differences in 5-LO activating protein (FLAP), COX-1 or COX-2. LTC4 synthase-positive cell counts correlated exclusively with mucosal eosinophils (r=0.94, p<0.001, n=25). Co-localisation confirmed that five-fold higher eosinophil counts (p=0.007) accounted for the increased LTC4 synthase expression in polyps from aspirin-intolerant asthmatic patients, with no alterations in mast cells or macrophages. Within the epithelium, increased counts of eosinophils (p=0.006), macrophages (p=0.097), and mast cells (p=0.034) in aspirin-intolerant asthmatic polyps were associated only with 2.5-fold increased 5-LO-positive cells (p<0.05), while the other enzymes were not different. Our results indicate that a marked over-representation of LTC4 synthase in mucosal eosinophils is closely linked to aspirin intolerance in the nasal airway, as in the bronchial airways.

Human bronchial fibroblasts express the 5-lipoxygenase pathway

Background

Fibroblasts are implicated in sub-epithelial fibrosis in remodeled asthmatic airways and contribute to airway inflammation by releasing cytokines and other mediators. Fibroblast activity is influenced by members of the leukotriene family of bronchoconstrictor and inflammatory mediators, but it is not known whether human bronchial fibroblasts can synthesize leukotrienes.

Methods

The expression of leukotriene biosynthetic enzymes and receptors was investigated in primary fibroblasts from the bronchi of normal and asthmatic adult subjects using RT-PCR, Western blotting, immunocytochemistry and flow cytometry.

Results

These techniques revealed that human bronchial fibroblasts from both subject groups constitutively express 5-lipoxygenase, its activating protein FLAP, the terminal enzymes leukotriene A₄ hydrolase and leukotriene C₄ synthase, and receptors for leukotriene B₄ (BLT1) and cysteinyl-leukotrienes (CysLT₁). Human bronchial fibroblasts generated immunoreactive leukotriene B₄ and cysteinyl-leukotrienes spontaneously and in increased amounts after calcium-dependent activation. Flow cytometry showed that human bronchial fibroblasts transformed to a myofibroblast-like phenotype by culture with transforming growth factor-β₁ expressed 320–400% more immunofluorescence for leukotriene C₄ synthase and CysLT₁ receptors, with 60–80% reductions in leukotriene A₄ hydrolase and BLT1 receptors.

Conclusion

These results indicate that human bronchial fibroblasts may not only respond to exogenous leukotrienes but also generate leukotrienes implicated in narrowing, inflammation and remodeling of the asthmatic airway.

Specific immunoglobulin E for staphylococcal enterotoxins in nasal polyps from patients with aspirin-intolerant asthma

BACKGROUND

Nasal polyps infiltrated with eosinophils are commonly found in chronic asthmatic patients, more frequently in those with aspirin-intolerant asthma (AIA) than aspirin-tolerant asthma (ATA). Some studies have suggested a contribution of superantigens derived from Staphylococcus sp to nasal polyposis and eosinophilia, but their relative importance in AIA and ATA subjects is unknown.

OBJECTIVE

We investigated whether local production of specific IgE to staphylococcal enterotoxins A and B (SEA and SEB) and relationships with markers of eosinophilic inflammation differ in the nasal polyps of AIA and ATA subjects.

METHODS

Fifteen AIA subjects with positive responses to lysine-aspirin bronchoprovocation and 15 ATA subjects underwent polypectomy. Immunoassays were used to quantify eosinophil cationic protein (ECP), IL-5, mast cell tryptase, soluble IL-2 receptors (sIL-2R), total IgE, and specific IgE for SEA and SEB.

RESULTS

ECP levels in nasal polyp homogenates were higher in AIA subjects than in ATA subjects (P < 0.02), with no significant differences in tryptase, IL-5 or sIL-2R. Total IgE, and specific IgE to both SEA and SEB, were detectable in some nasal polyps from both subject groups, but median levels were markedly higher in AIA subjects than in ATA subjects (P = 0.04, 0.01, 0.05, respectively). Levels of specific IgE to SEA and SEB correlated significantly with levels of ECP and IL-5, but not those of tryptase or sIL-2R.

CONCLUSION

These findings suggest that staphylococcal superantigens may drive local eosinophilic inflammation in nasal polyp tissue, and that this is exacerbated in subjects with AIA.

Promoter polymorphism in the 5-lipoxygenase (ALOX5) and 5-lipoxygenase-activating protein (ALOX5AP) genes and asthma susceptibility in a Caucasian population

BACKGROUND

5-Lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FLAP) are essential for cysteinyl-leukotriene (cys-LT) production, critical mediators in asthma.

OBJECTIVE

We sought to identify novel promoter polymorphisms within the FLAP (ALOX5AP) gene promoter and test the role of these and the previously identified 5-LO (ALOX5) Sp1 promoter polymorphism in asthma susceptibility.

METHODS

To assess genetic association with asthma phenotypes, we genotyped 341 Caucasian families (containing two asthmatic siblings) and non-asthmatic control subjects (n=184). Genetic association was determined by case-control and transmission disequilibrium test (TDT) analyses. To determine the functional role of polymorphisms on basal transcription, we generated ALOX5AP-promoter-luciferase constructs and transiently transfected human HeLa cells.

RESULTS

A novel G/A substitution at -336 bp and a poly(A) repeat (n=19 or 23) at position -169 to -146 bp were identified in the ALOX5AP promoter. Genotyping found the -336 A and poly(A19) alleles at frequencies of q=0.06 and 0.12, respectively. No ALOX5AP allele was associated with asthma or asthma-related phenotypes in case-control or TDT analyses. ALOX5AP-promoter-luciferase analyses did not support a functional role of the -336 or poly(A) polymorphism in determining basal transcription. The ALOX5 Sp1 polymorphism was predominantly homozygous wild-type 5/5 (frequency q=0.70) and heterozygous 4/5 (q=0.23) genotypes and no allele was associated with asthma or asthma-related phenotypes.

CONCLUSION

Taken together, these data do not support a significant role for these polymorphisms in genetic susceptibility to asthma in the Caucasian population.

Promoter polymorphism influences the effect of dexamethasone on transcriptional activation of the LTC4 synthase gene

The molecular mechanisms of corticosteroid action in asthma are gradually being elucidated. The LTC4S gene encodes for LTC(4) synthase, the terminal enzyme in the generation of cysteinyl-leukotrienes (cys-LTs), which are key mediators in the pathogenesis of asthma. We have identified a novel promoter polymorphism in LTC4S at position -1072 (G/A) and a -444 (A/C) polymorphism has previously been reported. We hypothesised that the LTC4S gene promoter may be a potential site of regulation by corticosteroids and that genetic polymorphism may determine their effects at this locus. Using in vitro transfection of promoter-reporter constructs, dexamethasone was shown to increase transcription of LTC4S by more than 50% for the -1072G/-444A, A-C and G-C haplotype constructs (P&<0.02), but to have no effect on the A-A haplotype (P=0.27). These data identify an interesting phenomenon that requires validation in a human study examining ex vivo production of LTC(4) in cells from genotyped asthmatic and nonasthmatic subjects. The 9% of the Caucasian asthmatic population with the A-A haplotype may have genetically predetermined lower cys-LT levels in the presence of corticosteroids compared to other patients. These findings have potential implications in the evaluation of combined corticosteroid and antileukotriene therapy in asthma.

Allelic association and functional studies of promoter polymorphism in the leukotriene C4 synthase gene (LTC4S) in asthma

BACKGROUND

LTC4 synthase is essential for the production of cysteinyl leukotrienes (Cys-LT), critical mediators in asthma. We have identified a novel promoter polymorphism at position -1072 (G/A) and a -444 (A/C) polymorphism has previously been reported. The role of these polymorphisms in the genetic susceptibility to asthma was examined.

METHODS

To test for genetic association with asthma phenotypes, 341 white families (two asthmatic siblings) and 184 non-asthmatic control subjects were genotyped. Genetic association was assessed using case control and transmission disequilibrium test (TDT) analyses. LTC4S promoter luciferase constructs and transiently transfected human HeLa and KU812F cells were generated to determine the functional role of these polymorphisms on basal transcription.

RESULTS

No associations were observed in case control analyses (-1072 A, q=0.09; -444 C, q=0.29); the TDT identified a borderline association between the -444 C allele and bronchial responsiveness to methacholine (p=0.065). Asthmatic children with the -444 C allele had a lower mean basal forced expiratory volume in 1 second (97.4 v 92.7% predicted, p=0.005). LTC4S promoter luciferase analyses provided no evidence for a functional role of either polymorphism in determining basal transcription.

CONCLUSION

This study does not support a role for these polymorphisms in genetic susceptibility to asthma but provides evidence to suggest a role in determining lung function parameters.

Cysteinyl leukotriene interactions with other mediators and with glucocorticosteroids during airway inflammation

Unexpected aspects of the antiasthmatic efficacy of leukotriene modifiers and glucocorticosteroids have been observed. For both classes, the observed effects may be partially explainable on the basis of underrecognized interactions involving leukotrienes. This review examines the interactions between leukotrienes and other mediators of asthma. It details the effects of glucocorticosteroids on leukotriene synthesis and on leukocyte populations in asthmatic airways. Unexpected controller effects of the leukotriene modifiers may reflect the fact that leukotrienes and other mediators of asthma, such as T(H)2 cytokines, positively influence each other's generation. The ability of the leukotriene modifiers to disrupt such extensive interactions means that other relevant mediators are targeted indirectly by leukotriene blockade. Among asthma therapies, the glucocorticosteroids have numerous anti-inflammatory activities, but their effects may be unpredictable. Many processes involved in inflammation appear to escape modulation by glucocorticosteroids, including leukotriene synthesis, and leukotriene generation is among them. Understanding whether glucocorticosteroids reduce cysteinyl leukotriene levels in the airway is important in determining the clinical value of combining glucocorticosteroid therapy with leukotriene modifier therapy.

Effects of cysteinyl leukotrienes and leukotriene receptor antagonists on markers of inflammation

The understanding that asthma pathophysiology includes an inflammatory component has spurred the more aggressive use of anti-inflammatory therapies and created a need for effective tools to measure inflammation. Biomarkers of airway inflammation proposed are obtained by methods that are direct but highly invasive (bronchial biopsy, bronchoalveolar lavage), moderately direct, and less invasive (indirect sputum, exhaled air, breath condensate) or indirect and least invasive (blood, urine). Several studies described in this review have implicated the cysteinyl leukotrienes (CysLTs) as inflammatory mediators in a wide range of diseases, implying that their biological activities reach far beyond acute bronchoconstriction, the activity traditionally ascribed to them. The validity of examining sputum for "biomarkers" has improved the understanding of asthma pathophysiology, optimization of asthma treatment and management, and investigation of the relation between CysLTs and airway inflammation in asthma. Nitric oxide is also a surrogate marker of asthma and reflects airway inflammation. The anti-inflammatory effects of the leukotriene receptor antagonists and the markers of their activity continue to grow.

Are cysteinyl leukotrienes involved in allergic responses in human skin?

BACKGROUND

Cysteinyl leukotrienes have been suggested to be involved in producing the symptoms of both the early and late phases of the allergic response in the lung and other tissues.

OBJECTIVE

To use scanning laser Doppler imaging, microdialysis and immunocytochemistry to explore the mediator and cellular mechanisms of the dermal allergic response.

METHODS

Thirteen atopic volunteers received intradermal injections into the forearm of grass pollen or D. pteronyssinus extract. Changes in dermal blood flow up to 8 h were monitored by scanning laser Doppler imaging. The release of histamine, PGD2 and LTC4/D4/E4 was assessed by dermal microdialysis. Skin biopsies were taken at 6 h to determine numbers of mast cells, eosinophils, basophils, Langerhans' cells, and monocytes/macrophages, and the expression of COX-1, COX-2, 5-LO and FLAP.

RESULTS

Allergen provocation produced an immediate weal and flare response followed by an erythematous induration peaking at 6 h. During the first hour, c. 84 pmoles of histamine and c. 0.3 pmoles of PGD2 were recovered by microdialysis (both P < 0.001) but LTC4/D4/E4 was undetectable. No histamine, PGD2 or LTC4/D4/E4 was detectable at later times. Immunocytochemical examination of biopsies taken at 8 h showed increased numbers of eosinophils and basophils and in COX-2, 5-LO and FLAP, but not COX-1. Expression of 5-LO and FLAP was associated primarily with eosinophils.

CONCLUSIONS

These findings suggest that inflammatory cells recruited to the site of allergen injection are not activated to release detectable amounts of cysteinyl leukotrienes. Hence, it is unlikely that the late-phase erythematous induration is mediated by this autocoid.

Role of cysteinyl leukotrienes in adenosine 5'-monophosphate induced bronchoconstriction in asthma

BACKGROUND

Adenosine induced bronchoconstriction in patients with asthma is thought to be mediated by the synthesis and release of autacoids from airway mast cells. In vitro, adenosine induced constriction of asthmatic bronchi is blocked by a combination of specific histamine and cysteinyl leukotriene receptor antagonists, but the relative contribution of these mediators in vivo is unclear. We hypothesised that adenosine induced bronchoconstriction in asthmatic patients may be blocked by pretreatment with the orally active selective cysteinyl leukotriene-1 (CysLT(1)) receptor antagonist, montelukast.

METHODS

In a randomised, double blind, crossover study, oral montelukast (10 mg) or placebo was administered once daily on two consecutive days to 18 patients with mild to moderate persistent atopic asthma. Incremental doses of adenosine 5'-monophosphate (AMP) from 0.39 to 400 mg/ml were inhaled by dosimeter and the dose producing a 20% fall in FEV(1) (PC(20)AMP) after AMP inhalation was recorded. Leukotriene E(4) (LTE(4)) urinary concentrations were measured by enzyme immunoassay 4 hours after AMP challenge.

RESULTS

Montelukast pretreatment provided highly significant protection against adenosine induced bronchoconstriction, with geometric mean PC(20)AMP values of 52.6 mg/ml (95% CI 35.2 to 78.7) after placebo and 123.9 mg/ml (95% CI 83.0 to 185.0) after montelukast (p=0.006). The geometric mean of the montelukast/placebo PC(20)AMP ratio was 2.4 (95% CI 1.3 to 4.2). Montelukast had no significant effect on 4 hour urinary excretion of LTE(4) compared with placebo.

CONCLUSIONS

Selective CysLT(1) receptor antagonism with montelukast provides highly significant protection against AMP induced bronchoconstriction in patients with atopic asthma, implying that cysteinyl leukotrienes are generated from airway mast cells through preferential activation of their A(2B) receptors.

Rhinovirus infection increases 5-lipoxygenase and cyclooxygenase-2 in bronchial biopsy specimens from nonatopic subjects

Rhinovirus infections cause wheeze, cough, and bronchial hyperresponsiveness. To investigate the involvement of cysteinyl-leukotrienes and prostanoids in these symptoms, bronchial biopsy specimens from 9 normal subjects (nonatopic and with no history of chronic lung disease) were immunostained for 5-lipoxygenase (5-LO) and cyclooxygenase (COX) pathway enzymes 2 weeks before and 4 days after experimental infection with human rhinovirus serotype 16. 5-LO-positive cell counts increased 9-fold (from 0.48 to 4.4 cells/mm(2); P <.05), and 5-LO-activating protein (FLAP)-positive cell counts increased 3.6-fold (from 1.8 to 6.5 cells/mm(2); P =.09). Levels of leukotriene A(4) hydrolase and leukotriene C(4) synthase were unchanged. COX-2--positive cell counts increased from 0 to 2.6 cells/mm(2) (P =.009), with no change in COX-1 levels. Increases of 3-4-fold were seen in levels of macrophages (P =.02) and mast cells (P =.07) but not of eosinophils (P >.4), and bronchoalveolar lavage fluid cysteinyl-leukotriene levels doubled (from 11.2 to 20.4 pg/mL; P =.13). Cold symptom scores correlated with bronchial immunostaining for FLAP (rho = 0.93; P =.001). In normal subjects, rhinovirus colds induce bronchial inflammation with markedly enhanced expression of 5-LO pathway proteins and COX-2.

Leukotriene and prostanoid pathway enzymes in bronchial biopsies of seasonal allergic asthmatics

Cysteinyl-leukotrienes and prostaglandin D2 generated by the 5-lipoxygenase (5-LO) and cyclooxygenase (COX) pathways, respectively, cause bronchoconstriction, leukocyte recruitment, and bronchial hyperresponsiveness in asthma. We characterized the cellular expression of 5-LO and COX enzymes using immunohistochemistry on bronchial biopsies from 12 allergic asthmatic patients before and during seasonal exposure to birch pollen. Bronchial responsiveness (p = 0.004) and symptoms (p < 0.005) increased and peak expiratory flow (PEF; p < or = 0.02) decreased in the pollen season. In-season biopsies had 2-fold more cells immunostaining for 5-LO (p = 0.02), 5-LO-activating protein (FLAP; p = 0.04), and leukotriene (LT)A4 hydrolase (p = 0.05), and 4-fold more for the terminal enzyme for cysteinyl-leukotriene synthesis, LTC4 synthase (p = 0.02). Immunostaining for COX-1, COX-2, and PGD2 synthase was unchanged. Increased staining for LTC4 synthase was due to increased eosinophils (p = 0.035) and an increased proportion of eosinophils expressing the enzyme (p = 0.047). Macrophages also increased (p = 0.019), but mast cells and T-lymphocyte subsets were unchanged. Inverse correlations between PEF and 5-LO(+) cell counts link increased expression of 5-LO pathway enzymes in eosinophils and macrophages within the bronchial mucosa to deterioration of lung function during seasonal allergen exposure.

The anti-inflammatory effects of leukotriene-modifying drugs and their use in asthma

Asthma is a chronic inflammatory disease of the airways. Anti-inflammatory drug therapy, primarily using corticosteroids, is now considered the first-line treatment in the management of all grades of asthma severity. Although corticosteroids are believed to be the most potent anti-inflammatory agents available, they do not suppress all inflammatory mediators involved in the asthmatic response. Leukotrienes, which are lipid mediators generated from the metabolism of arachidonic acid, play an important role in the pathogenesis of asthma. They produce bronchospasm, increase bronchial hyperresponsiveness, mucus production, and mucosal edema, and enhance airway smooth muscle cell proliferation and eosinophil recruitment into the airways, and their synthesis or release is unaffected by corticosteroid administration. The use of leukotriene synthesis inhibitors or leukotriene receptor antagonists as anti-inflammatory therapies in asthma has therefore been investigated. Beneficial effects of leukotriene-modifying drugs have been demonstrated in the management of all grades of asthma severity, and there is evidence that certain patient groups (such as those with exercise-induced asthma or aspirin-induced asthma) may be particularly suitable for such therapy.

n-3 polyunsaturated fatty acid supplementation, monocyte adhesion molecule expression and pro-inflammatory mediators in Type 2 diabetes mellitus

AIMS

To examine the effect of n-3 polyunsaturated fatty acid supplements on the monocyte surface expression of adhesion molecules involved in proatherogenic monocyte-endothelial interactions, and on pro-inflammatory mediators in Type 2 diabetes mellitus.

METHODS

Twenty-nine subjects with Type 2 diabetes and 21 controls without diabetes were studied. Monocyte expression of leucocyte function-associated antigens 1 and 3, intercellular adhesion molecule-1, and the major histocompatibility complex class II molecule HLA-DR were measured using a laser flow cytometric method. Supplementation with 2.08 g n-3 fatty acids for 21 days was undertaken and measurements repeated. Plasma soluble adhesion molecule concentrations, plasminogen activator inhibitor-1 activity and antigen and pro-inflammatory mediators (cysteinyl leukotriene and monocyte leukotriene B4) were also measured.

RESULTS

Groups did not differ in monocyte expression of adhesion molecules or HLA-DR, or in leukotriene production although plasma soluble adhesion molecule concentrations were higher in the diabetes groups (P<0.05). n-3 fatty acid supplementation influenced neither the expression of these molecules nor plasma soluble adhesion molecule concentrations or leukotriene production.

CONCLUSIONS

This study does not support increased monocyte adhesion molecule expression or abnormal monocyte production of pro-inflammatory mediators as mechanisms for increased atherogenic risk in Type 2 diabetes. Cardioprotective actions of n-3 fatty acids may not be mediated through these mechanisms.

The role of eosinophils and neutrophils in inflammation

The eosinophil is well recognized as a central effector cell in the inflamed asthmatic airway. Eosinophils release toxic basic proteins and lipid mediators such as cysteinyl-leukotrienes that cause bronchial epithelial damage and airflow obstruction. Eosinophil-selective cytokines and chemokines including interleukin (IL)-5, eotaxin and RANTES may represent targets for novel asthma therapies. In contrast, the role of the neutrophil in asthma remains relatively obscure. Recent evidence from the ENFUMOSA project and elsewhere suggests that neutrophils not only contribute to acute asthma exacerbations, but also are present in high numbers in the airways of patients with chronic severe asthma. Production by neutrophils of lipid mediators, reactive oxygen intermediates (ROI) and proteases such as elastase, may contribute to airflow obstruction, epithelial damage and remodelling. Leukotriene B4 and cytokines such as IL-8, granulocyte-macrophage colony stimulating factor (GM-CSF), and tumour necrosis factor (TNF)alpha chemoattract neutrophils and reduce neutrophil apoptosis, and selective agents directed against these may prevent neutrophil influx and accumulation. Airway neutrophilia remains apparent in severe asthma patients even after treatment with high doses of corticosteroids. In vitro, corticosteroids paradoxically enhance neutrophil survival by reducing apoptosis, so corticosteroid therapy may exacerbate neutrophil activity in vivo. Both corticosteroids and cytokines may suppress neutrophil apoptosis by upregulating endogenous synthesis of leukotriene (LT)B4. Specific blockade of LTB4 synthesis or LTB4 receptors may induce neutrophil apoptosis and combat the unwanted effects of high-dose steroids on neutrophil survival. Phagocytosis of apoptotic neutrophils stimulates important signals that down-regulate pro-inflammatory cytokine production by macrophages, allowing resolution and repair processes to prevail.

The role of eosinophils and neutrophils in inflammation

The eosinophil is well recognized as a central effector cell in the inflamed asthmatic airway. Eosinophils release toxic basic proteins and lipid mediators such as cysteinyl-leukotrienes that cause bronchial epithelial damage and airflow obstruction. Eosinophil-selective cytokines and chemokines including interleukin (IL)-5, eotaxin and RANTES may represent targets for novel asthma therapies. In contrast, the role of the neutrophil in asthma remains relatively obscure. Recent evidence from the ENFUMOSA project and elsewhere suggests that neutrophils not only contribute to acute asthma exacerbations, but also are present in high numbers in the airways of patients with chronic severe asthma. Production by neutrophils of lipid mediators, reactive oxygen intermediates (ROI) and proteases such as elastase, may contribute to airflow obstruction, epithelial damage and remodelling. Leukotriene B4 and cytokines such as IL-8, granulocyte-macrophage colony stimulating factor (GM-CSF), and tumour necrosis factor (TNF)alpha chemoattract neutrophils and reduce neutrophil apoptosis, and selective agents directed against these may prevent neutrophil influx and accumulation. Airway neutrophilia remains apparent in severe asthma patients even after treatment with high doses of corticosteroids. In vitro, corticosteroids paradoxically enhance neutrophil survival by reducing apoptosis, so corticosteroid therapy may exacerbate neutrophil activity in vivo. Both corticosteroids and cytokines may suppress neutrophil apoptosis by upregulating endogenous synthesis of leukotriene (LT)B4. Specific blockade of LTB4 synthesis or LTB4 receptors may induce neutrophil apoptosis and combat the unwanted effects of high-dose steroids on neutrophil survival. Phagocytosis of apoptotic neutrophils stimulates important signals that down-regulate pro-inflammatory cytokine production by macrophages, allowing resolution and repair processes to prevail.

Production of the potent neutrophil chemokine, growth-related protein alpha (GROalpha), is not elevated in cystic fibrosis children

Progressive neutrophil-mediated lung damage causes much of the morbidity and mortality in cystic fibrosis (CF). Neutrophil chemoattractants implicated in CF include interleukin (IL-)8, tumour necrosis factor (TNFalpha) and leukotriene (LT)B4, but growth-related protein alpha (GROalpha), a highly potent neutrophil chemokine, has not been investigated. Atopic status has been considered to contribute to the marked heterogeneity of pulmonary disease in CF. We hypothesized that GROalpha may be produced in biologically-significant amounts in the CF lung, and that enhanced production of GROalpha, IL-8 or LTB4 may contribute to the poorer lung function seen in atopic CF patients compared to non-atopic CF patients. GROalpha, IL-8 and LTB4 levels in the sputum of atopic and non-atopic CF patients were assessed by immunoassays, and GROalpha and IL-8 levels were also assessed in the plasma of CF patients and normal controls. As expected, there were high levels of IL-8 and LTB4 in most CF sputum samples, and IL-8 levels were higher in CF plasma than in control plasma (P=0.02). In contrast, GROalpha was undetectable (< 5 pg ml(-1)) in the sputum of 21 out of 25 CF patients, with low levels (range 144-825 pg ml(-1)) in the remainder, and median levels of GROalpha in CF plasma (33 pg ml(-1), n=24) were not significantly different from controls (34 pg ml(-1), n=25). Lung function [forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC)] was significantly poorer in atopic CF compared to non-atopic CF patients (P<0.02), but sputum levels of GROalpha, IL-8 and LTB4 were not different between the subgroups. Our results suggest that unlike LTB4 and IL-8, GROalpha does not contribute to neutrophilic inflammation in the CF lung, and other factors must determine the impaired lung function observed in atopic CF patients. These results may have important implications in the development of chemokine receptor antagonists as novel anti-inflammatory agents in CF.

Exposure to systemic prednisolone for 4 hours reduces ex vivo synthesis of GM-CSF by bronchoalveolar lavage cells and blood mononuclear cells of mild allergic asthmatics

BACKGROUND

In acute severe asthma, the earliest clinical effects of glucocorticosteroids occur from 4 to 5 h after systemic administration, but the mechanisms are unclear. In persistent asthma, corticosteroids are thought to suppress airway inflammation by modulating the expression of adhesion molecules, enzymes, and leucotactic cytokines, including granulocyte-macrophage colony stimulating factor (GM-CSF). GM-CSF is also overexpressed in the airways of symptomatic asthmatics.

OBJECTIVES

To examine the early effects of systemic corticosteroids on cytokine expression, we investigated whether ex vivo synthesis of GM-CSF is suppressed in the bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMCs) of normal and mild allergic asthmatic subjects obtained 4 h after a single intravenous dose of prednisolone.

METHODS

In a randomized, double-blind, placebo-controlled study, BAL cells and PBMCs were obtained from mild atopic asthmatic patients (n = 9) and normal subjects (n = 9) 4 h after an intravenous bolus dose of 80 mg prednisolone, and cultured for 0-18 h in the presence or absence of lipopolysaccharide (LPS; 10 microg/mL). Enzyme immunoassay was used to assess GM-CSF levels in BAL cell and PBMC culture supernatants, and in BAL fluid.

RESULTS

After placebo, GM-CSF synthesis tended to be higher in BAL cells from asthmatics than in normals. LPS stimulation significantly increased median (interquartile range) GM-CSF synthesis by BAL cells ex vivo from 16.4 (23 to 74) to 35.8 (3-148) pg/106 cells in normals (P < 0.05), and from 59 (9 to 204) to 134 (24-288) pg/106 cells in asthmatics (P < 0.01). After intravenous prednisolone, the rise in GM-CSF production induced in BAL cells by LPS was completely abolished in both subject groups. In PBMCs of placebo-treated asthmatics (but not normals), LPS stimulated median GM-CSF synthesis from 164 (110 to 300) to 314 (235-485) pg/106 cells (P = 0.02), and this was blocked by intravenous prednisolone.

CONCLUSIONS

LPS-stimulated GM-CSF synthesis ex vivo is abolished in BAL cells of mild asthmatic and normal subjects, and in PBMCs of asthmatics, obtained 4 h after a single intravenous dose of prednisolone. Suppression of GM-CSF synthesis in airway and blood leucocytes may contribute to the early clinical efficacy of systemic glucocorticoids in acute allergic asthma.

Effect of intravenous corticosteroid on ex vivo leukotriene generation by blood leucocytes of normal and asthmatic patients

BACKGROUND

The cysteinyl-leukotrienes (LTC(4), LTD(4), LTE(4)) are critical bronchoconstrictor and eosinophilotactic mediators in asthma while LTB(4) is a potent neutrophil chemoattractant. Glucocorticosteroids are front line anti-inflammatory treatment for asthma but the evidence that they reduce leukotriene (LT) synthesis in vivo is poor.

METHODS

In a randomised, double blind, placebo controlled, crossover trial immunoassays were used to measure ex vivo synthesis of LTC(4) and LTB(4) by calcium ionophore stimulated blood leucocytes and bronchoalveolar lavage (BAL) cells of eight normal subjects and eight patients with mild allergic asthma 4-6 hours after intravenous administration of a single 100 mg dose of methylprednisolone.

RESULTS

Ionophore stimulated synthesis of LTC(4) (but not LTB(4)) in blood granulocytes tended to be higher in asthmatic subjects (mean 9.7 ng/10(6) cells) than in normal subjects (4.2 ng/10(6) cells; p = 0.08) and intravenous methylprednisolone reduced synthesis of LTC(4) (but not LTB(4)) to normal levels (2.9 ng/10(6) cells; 95% CI for the reduction 1.0 to 12.5 ng/10(6) cells; p = 0.03). In blood mononuclear cells methylprednisolone reduced LTC(4) synthesis in asthmatic subjects from 1.26 to 0.79 ng/10(6) cells (95% CI for the reduction 0.26 to 0.79, p = 0.014) and tended to reduce LTC(4) synthesis in normal subjects from 1.51 to 0.86 ng/10(6) cells (p = 0.08). Methylprednisolone also significantly reduced synthesis of LTB(4) in mononuclear cells from both subject groups (p = 0.014). It had no effect on LT synthesis in BAL cells from either group nor on LT levels in BAL fluid.

CONCLUSIONS

Intravenous methylprednisolone can reduce synthesis of leukotrienes in blood granulocytes and mononuclear cells within six hours of a single intravenous dose.

IL-5 increases expression of 5-lipoxygenase-activating protein and translocates 5-lipoxygenase to the nucleus in human blood eosinophils

Cysteinyl-leukotrienes are potent bronchoconstrictor mediators synthesized by the 5-lipoxygenase (5-LO) pathway. Eosinophilopoietic cytokines such as IL-5 enhance cysteinyl-leukotriene synthesis in eosinophils in vitro, mimicking changes in eosinophils from asthmatic patients, but the mechanism is unknown. We hypothesized that IL-5 induces the expression of 5-LO and/or its activating protein FLAP in eosinophils, and that this might be modulated by anti-inflammatory corticosteroids. Compared with control cultures, IL-5 increased the proportion of normal blood eosinophils immunostaining for FLAP (65 +/- 4 vs 34 +/- 4%; p < 0.0001), enhanced immunoblot levels of FLAP by 51 +/- 14% (p = 0.03), and quadrupled ionophore-stimulated leukotriene C4 synthesis from 5.7 to 20.8 ng/106 cells (p < 0.02). IL-5 effects persisted for 24 h and were abolished by cycloheximide and actinomycin D. The proportion of FLAP+ eosinophils was also increased by dexamethasone (p < 0.0001). Neither IL-5 nor dexamethasone altered 5-LO expression, but IL-5 significantly increased 5-LO immunofluorescence localizing to eosinophil nuclei. Compared with normal subjects, allergic asthmatic patients had a greater proportion of circulating FLAP+ eosinophils (46 +/- 6 vs 27 +/- 3%; p < 0.03) and a smaller IL-5-induced increase in FLAP immunoreactivity (p < 0.05). Thus, IL-5 increases FLAP expression and translocates 5-LO to the nucleus in normal blood eosinophils in vitro. This is associated with an enhanced capacity for cysteinyl-leukotriene synthesis and mimics in vivo increases in FLAP expression in eosinophils from allergic asthmatics.

IL-5 Increases Expression of 5-Lipoxygenase-Activating Protein and Translocates 5-Lipoxygenase to the Nucleus in Human Blood Eosinophils

Cysteinyl-leukotrienes are potent bronchoconstrictor mediators synthesized by the 5-lipoxygenase (5-LO) pathway. Eosinophilopoietic cytokines such as IL-5 enhance cysteinyl-leukotriene synthesis in eosinophils in vitro, mimicking changes in eosinophils from asthmatic patients, but the mechanism is unknown. We hypothesized that IL-5 induces the expression of 5-LO and/or its activating protein FLAP in eosinophils, and that this might be modulated by anti-inflammatory corticosteroids. Compared with control cultures, IL-5 increased the proportion of normal blood eosinophils immunostaining for FLAP (65 ± 4 vs 34 ± 4%; p &lt; 0.0001), enhanced immunoblot levels of FLAP by 51 ± 14% (p = 0.03), and quadrupled ionophore-stimulated leukotriene C4 synthesis from 5.7 to 20.8 ng/106 cells (p &lt; 0.02). IL-5 effects persisted for 24 h and were abolished by cycloheximide and actinomycin D. The proportion of FLAP+ eosinophils was also increased by dexamethasone (p &lt; 0.0001). Neither IL-5 nor dexamethasone altered 5-LO expression, but IL-5 significantly increased 5-LO immunofluorescence localizing to eosinophil nuclei. Compared with normal subjects, allergic asthmatic patients had a greater proportion of circulating FLAP+ eosinophils (46 ± 6 vs 27 ± 3%; p &lt; 0.03) and a smaller IL-5-induced increase in FLAP immunoreactivity (p &lt; 0.05). Thus, IL-5 increases FLAP expression and translocates 5-LO to the nucleus in normal blood eosinophils in vitro. This is associated with an enhanced capacity for cysteinyl-leukotriene synthesis and mimics in vivo increases in FLAP expression in eosinophils from allergic asthmatics.