Timing of radiotherapy (RT) after radical prostatectomy (RP): long-term outcomes in the RADICALS-RT trial (NCT00541047).

BACKGROUND: The optimal timing of radiotherapy (RT) after radical prostatectomy for prostate cancer has been uncertain. RADICALS-RT compared efficacy and safety of adjuvant RT versus an observation policy with salvage RT for prostate-specific antigen (PSA) failure. PATIENTS AND METHODS: RADICALS-RT was a randomised controlled trial enrolling patients with ≥1 risk factor (pT3/4, Gleason 7-10, positive margins, preoperative PSA≥10 ng/ml) for recurrence after radical prostatectomy. Patients were randomised 1:1 to adjuvant RT ('Adjuvant-RT') or an observation policy with salvage RT for PSA failure ('Salvage-RT') defined as PSA≥0.1 ng/ml or three consecutive rises. Stratification factors were Gleason score, margin status, planned RT schedule (52.5 Gy/20 fractions or 66 Gy/33 fractions) and treatment centre. The primary outcome measure was freedom-from-distant-metastasis (FFDM), designed with 80% power to detect an improvement from 90% with Salvage-RT (control) to 95% at 10 years with Adjuvant-RT. Secondary outcome measures were biochemical progression-free survival, freedom from non-protocol hormone therapy, safety and patient-reported outcomes. Standard survival analysis methods were used; hazard ratio (HR)<1 favours Adjuvant-RT. RESULTS: Between October 2007 and December 2016, 1396 participants from UK, Denmark, Canada and Ireland were randomised: 699 Salvage-RT, 697 Adjuvant-RT. Allocated groups were balanced with a median age of 65 years. Ninety-three percent (649/697) Adjuvant-RT reported RT within 6 months after randomisation; 39% (270/699) Salvage-RT reported RT during follow-up. Median follow-up was 7.8 years. With 80 distant metastasis events, 10-year FFDM was 93% for Adjuvant-RT and 90% for Salvage-RT: HR=0.68 [95% confidence interval (CI) 0.43-1.07, P=0.095]. Of 109 deaths, 17 were due to prostate cancer. Overall survival was not improved (HR=0.980, 95% CI 0.667-1.440, P=0.917). Adjuvant-RT reported worse urinary and faecal incontinence 1 year after randomisation (P=0.001); faecal incontinence remained significant after 10 years (P=0.017). CONCLUSION: Long-term results from RADICALS-RT confirm adjuvant RT after radical prostatectomy increases the risk of urinary and bowel morbidity, but does not meaningfully improve disease control. An observation policy with salvage RT for PSA failure should be the current standard after radical prostatectomy. TRIAL IDENTIFICATION: RADICALS, RADICALS-RT, ISRCTN40814031, NCT00541047.

Airway and peripheral urokinase plasminogen activator receptor is elevated in asthma, and identifies a severe, nonatopic subset of patients.

RATIONALE: Genetic polymorphisms in the asthma susceptibility gene, urokinase plasminogen activator receptor (uPAR/PLAUR) have been associated with lung function decline and uPAR blood levels in asthma subjects. Preliminary studies have identified uPAR elevation in asthma; however, a definitive study regarding which clinical features of asthma uPAR may be driving is currently lacking. OBJECTIVES: We aimed to comprehensively determine the uPAR expression profile in asthma and control subjects utilizing bronchial biopsies and serum, and to relate uPAR expression to asthma clinical features. METHODS: uPAR levels were determined in control (n = 9) and asthmatic (n = 27) bronchial biopsies using immunohistochemistry, with a semi-quantitative score defining intensity in multiple cell types. Soluble-cleaved (sc) uPAR levels were determined in serum through ELISA in UK (cases n = 129; controls n = 39) and Dutch (cases n = 514; controls n = 96) cohorts. MEASUREMENTS AND MAIN RESULTS: In bronchial tissue, uPAR was elevated in inflammatory cells in the lamina propria (P = 0.0019), bronchial epithelial (P = 0.0002) and airway smooth muscle cells (P = 0.0352) of patients with asthma, with uPAR levels correlated between the cell types. No correlation with disease severity or asthma clinical features was identified. scuPAR serum levels were elevated in patients with asthma (1.5-fold; P = 0.0008), and we identified an association between high uPAR serum levels and severe, nonatopic disease. CONCLUSIONS: This study provides novel data that elevated airway and blood uPAR is a feature of asthma and that blood uPAR is particularly related to severe, nonatopic asthma. The findings warrant further investigation and may provide a therapeutic opportunity for this refractory population.

Chemoradiotherapy with Brachytherapy or Electron Therapy Boost for Locally Advanced Squamous Cell Carcinoma of the Anus-Reducing the Colostomy Rate.

PURPOSE: The aim of this study is to determine overall survival, disease-specific survival and stoma-free survival after treatment of squamous cell carcinoma of the anus with chemoradiotherapy followed by brachytherapy or electron boost in a recent cohort of patients. METHODS: Fifty-two patients (median age 62 years) were treated with radical chemoradiotherapy (mitomycin C, infusional 5-fluorouracil concurrently with conformal radical radiotherapy 45 Gy in 25 fractions over 5 weeks) followed by a radiotherapy boost between 1 December 2000 and 30 April 2011. Follow-up was to 30 November 2014. Thirty-six patients received a boost (15-20 Gy) over 2 days with 192Ir needle brachytherapy for anal canal tumours, and 16 patients received electron beam therapy (20 Gy in 10 fractions in 2 weeks) for anal margin tumours. A defunctioning stoma was only created prior to chemoradiotherapy for fistula or severe anal pain. RESULTS: The overall survival for the 36 patients treated with chemoradiotherapy followed by brachytherapy was 75 % (95 % CI, 61-89) at 5 years, the disease-specific survival was 91 % (95 % CI, 81-101 %), and the stoma-free survival was 97 % (95 % CI, 91-103 %) all at 5 years. For the 16 patients treated with an electron boost for anal margin tumours, the 5-year overall survival, disease-specific survival and stoma-free survival were 68 % (95 % CI, 44-92 %), 78 % (95 % CI, 56-100 %) and 80 % (95 % CI, 60-100 %), respectively. CONCLUSIONS: A very low stoma formation rate can be obtained with radical chemoradiotherapy followed by a brachytherapy boost for squamous cell carcinoma of the anal canal but not with an electron boost for anal margin tumours.

Genes associated with polymorphic variants predicting lung function are differentially expressed during human lung development.

BACKGROUND: Recent meta-analyses of genome-wide association studies have identified single nucleotide polymorphisms (SNPs) within/near 54 genes associated with lung function measures. Current understanding of the contribution of these genes to human lung development is limited. We set out to further define i) the expression profile of these genes during human lung development using a unique set of resources to examine both mRNA and protein expression and ii) the link between key polymorphisms and genes using expression quantitative trait loci (eQTL) approaches. METHODS: The mRNA expression profile of lung function associated genes across pseudoglandular and canalicular stages of lung development were determined using expression array data of 38 human fetal lungs. eQTLs were investigated for selected genes using blood cell and lung tissue data. Immunohistochemistry of the top 5 candidates was performed in a panel of 24 fetal lung samples. RESULTS: Twenty-nine lung function associated genes were differentially expressed during lung development at the mRNA level. The greatest magnitude of effect was observed for 5 genes; TMEM163, FAM13A and HHIP which had increasing expression and CDC123 and PTCH1 with decreased expression across developmental stages. Focussed eQTL analyses investigating SNPs in these five loci identified several cis-eQTL's. Protein expression of TMEM163 increased and CDC123 decreased with fetal lung age in agreement with mRNA data. Protein expression in FAM13A, HHIP and PTCH1 remained relatively constant throughout lung development. CONCLUSIONS: We have identified that > 50 % of lung function associated genes show evidence of differential expression during lung development and we show that in particular TMEM163 and CDC123 are differentially expressed at both the mRNA and protein levels. Our data provides a systematic evaluation of lung function associated genes in this context and offers some insight into the potential role of several of these genes in contributing to human lung development.

Translating Lung Function Genome-Wide Association Study (GWAS) Findings: New Insights for Lung Biology.

Chronic respiratory diseases are a major cause of worldwide mortality and morbidity. Although hereditary severe deficiency of α1 antitrypsin (A1AD) has been established to cause emphysema, A1AD accounts for only ∼ 1% of Chronic Obstructive Pulmonary Disease (COPD) cases. Genome-wide association studies (GWAS) have been successful at detecting multiple loci harboring variants predicting the variation in lung function measures and risk of COPD. However, GWAS are incapable of distinguishing causal from noncausal variants. Several approaches can be used for functional translation of genetic findings. These approaches have the scope to identify underlying alleles and pathways that are important in lung function and COPD. Computational methods aim at effective functional variant prediction by combining experimentally generated regulatory information with associated region of the human genome. Classically, GWAS association follow-up concentrated on manipulation of a single gene. However association data has identified genetic variants in >50 loci predicting disease risk or lung function. Therefore there is a clear precedent for experiments that interrogate multiple candidate genes in parallel, which is now possible with genome editing technology. Gene expression profiling can be used for effective discovery of biological pathways underpinning gene function. This information may be used for informed decisions about cellular assays post genetic manipulation. Investigating respiratory phenotypes in human lung tissue and specific gene knockout mice is a valuable in vivo approach that can complement in vitro work. Herein, we review state-of-the-art in silico, in vivo, and in vitro approaches that may be used to accelerate functional translation of genetic findings.

The challenge of measuring IL-33 in serum using commercial ELISA: lessons from asthma.

BACKGROUND: Interleukin-33 (IL-33) has been subject of extensive study in the context of inflammatory disorders, particularly in asthma. Many human biological samples, including serum, have been used to determine the protein levels of IL-33, aiming to investigate its involvement in asthma. Reliable methods are required to study the association of IL-33 with disease, especially considering the complex nature of serum samples. OBJECTIVE: We evaluated four IL-33 ELISA kits, aiming to determine a robust and reproducible approach to quantifying IL-33 in human serum from asthma patients. METHODS: IL-33 levels were investigated in serum of well-defined asthma patients by the Quantikine, DuoSet (both R&D systems), ADI-900-201 (Enzo Life Sciences), and SKR038 (GenWay Biotech Inc San Diego USA) immunoassays, as well as spiking experiments were performed using recombinant IL-33 and its soluble receptor IL-1RL1-a. RESULTS: We show that 1) IL-33 is difficult to detect by ELISA in human serum, due to lack of sensitivity and specificity of currently available assays; 2) human serum interferes with IL-33 quantification, in part through IL-1RL1-a; and 3) using non-serum certified kits may lead to spurious findings. CONCLUSION AND CLINICAL RELEVANCE: If IL-33 is to be studied in the serum of asthma patients and other diseases, a more sensitive and specific assay method is required, which will be vital for further understanding and targeting of the IL-33/IL-1RL1 axis in human disease.

Genetic risk factors for the development of allergic disease identified by genome-wide association.

An increasing proportion of the worldwide population is affected by allergic diseases such as allergic rhinitis (AR), atopic dermatitis (AD) and allergic asthma and improved treatment options are needed particularly for severe, refractory disease. Allergic diseases are complex and development involves both environmental and genetic factors. Although the existence of a genetic component for allergy was first described almost 100 years ago, progress in gene identification has been hindered by lack of high throughput technologies to investigate genetic variation in large numbers of subjects. The development of Genome-Wide Association Studies (GWAS), a hypothesis-free method of interrogating large numbers of common variants spanning the entire genome in disease and non-disease subjects has revolutionised our understanding of the genetics of allergic disease. Susceptibility genes for asthma, AR and AD have now been identified with confidence, suggesting there are common and distinct genetic loci associated with these diseases, providing novel insights into potential disease pathways and mechanisms. Genes involved in both adaptive and innate immune mechanisms have been identified, notably including multiple genes involved in epithelial function/secretion, suggesting that the airway epithelium may be particularly important in asthma. Interestingly, concordance/discordance between the genetic factors driving allergic traits such as IgE levels and disease states such as asthma have further supported the accumulating evidence for heterogeneity in these diseases. While GWAS have been useful and continue to identify novel genes for allergic diseases through increased sample sizes and phenotype refinement, future approaches will integrate analyses of rare variants, epigenetic mechanisms and eQTL approaches, leading to greater insight into the genetic basis of these diseases. Gene identification will improve our understanding of disease mechanisms and generate potential therapeutic opportunities.

Impact of the introduction of weekly radiotherapy quality assurance meetings at one UK cancer centre.

OBJECTIVE: The complexity of radiotherapy planning is increasing rapidly. Delivery and planning is subject to detailed quality assurance (QA) checks. The weakest link is often the oncologists' delineation of the clinical target volume (CTV). Weekly departmental meetings for radiotherapy QA (RTQA) were introduced into the Royal Wolverhampton Hospital, Wolverhampton, UK, in October 2011. This article describes the impact of this on patient care. METHODS: CTVs for megavoltage photon radiotherapy courses for all radical, adjuvant and palliative treatments longer than five fractions (with the exception of two field tangential breast treatments not enrolled into clinical trials) were reviewed in the RTQA meeting. Audits were carried out in January 2012 (baseline) and September 2013, each over a 4-week period. Adherence to departmental contouring protocols was assessed and the number of major and minor alterations following peer review were determined. RESULTS: There was no statistically significant difference for major alterations between the two study groups; 8 alterations in 80 patients (10%) for the baseline audit vs 3 alterations from 72 patients (4.2%) in the second audit (p = 0.17). A trend towards a reduction in alterations following peer review was observed. There has, however, been a change in practice resulting in a reduction in variation in CTV definition within our centre and greater adherence to protocols. There is increasing confidence in the quality and constancy of care delivered. CONCLUSION: Introduction of a weekly QA meeting for target volume definition has facilitated consensus and adoption of departmental clinical guidelines within the unit. ADVANCES IN KNOWLEDGE: The weakest areas in radiotherapy are patient selection and definition of the CTV. Engagement in high-quality RTQA is paramount. This article describes the impact of this in one UK cancer centre.

Genome-wide association study to identify genetic determinants of severe asthma.

BACKGROUND: The genetic basis for developing asthma has been extensively studied. However, association studies to date have mostly focused on mild to moderate disease and genetic risk factors for severe asthma remain unclear. OBJECTIVE: To identify common genetic variants affecting susceptibility to severe asthma. METHODS: A genome-wide association study was undertaken in 933 European ancestry individuals with severe asthma based on Global Initiative for Asthma (GINA) criteria 3 or above and 3346 clean controls. After standard quality control measures, the association of 480 889 genotyped single nucleotide polymorphisms (SNPs) was tested. To improve the resolution of the association signals identified, non-genotyped SNPs were imputed in these regions using a dense reference panel of SNP genotypes from the 1000 Genomes Project. Then replication of SNPs of interest was undertaken in a further 231 cases and 1345 controls and a meta-analysis was performed to combine the results across studies. RESULTS: An association was confirmed in subjects with severe asthma of loci previously identified for association with mild to moderate asthma. The strongest evidence was seen for the ORMDL3/GSDMB locus on chromosome 17q12-21 (rs4794820, p=1.03×10((-8)) following meta-analysis) meeting genome-wide significance. Strong evidence was also found for the IL1RL1/IL18R1 locus on 2q12 (rs9807989, p=5.59×10((-8)) following meta-analysis) just below this threshold. No novel loci for susceptibility to severe asthma met strict criteria for genome-wide significance. CONCLUSIONS: The largest genome-wide association study of severe asthma to date was carried out and strong evidence found for the association of two previously identified asthma susceptibility loci in patients with severe disease. A number of novel regions with suggestive evidence were also identified warranting further study.

Polymorphisms in IL13 pathway genes in asthma and chronic obstructive pulmonary disease.

BACKGROUND: Asthma and chronic obstructive pulmonary disease (COPD) are chronic respiratory diseases involving an interaction between genetic and environmental factors. Interleukin-13 (IL13) has been suggested to have a role in both asthma and COPD. We investigated whether single nucleotide polymorphisms (SNPs) in the IL13 pathway may contribute to the susceptibility and severity of asthma and COPD in adults. METHODS: Twelve SNPs in IL13 pathway genes -IL4, IL13, IL4RA, IL13RA1, IL13RA2 and STAT6- were genotyped in subjects with asthma (n = 299) and in subjects with COPD or healthy smokers (n = 992). Genetic association was evaluated using genotype and allele models for asthma severity, atopy phenotypes and COPD susceptibility. Linear regression was used to determine the effects of polymorphism on baseline lung function (FEV(1), FEV(1)/FVC). RESULTS: In asthmatics, three IL13 SNPs - rs1881457(-1512), rs1800925(-1111) and rs20541(R130Q) - were associated with atopy risk. One SNP in IL4RA1 [rs1805010(I75V)] was associated with asthma severity, and several IL13 SNPs showed borderline significance. IL13 SNPs rs1881457(-1512) and rs1800925(-1111) were associated with better FEV(1) and FEV(1)/FVC in asthmatics. IL13 SNPs rs2066960(intron 1), rs20541(R130Q) and rs1295685(exon 4) were associated with COPD risk and lower baseline lung function in the recessive model. In females, but not in males, rs2250747 of the IL13RA1 gene was associated with COPD and lower FEV(1). CONCLUSION: These data suggest that IL13 SNPs (promoter and coding region) and, to a lesser extent, IL4RA SNPs may contribute to atopy and asthma. We also provide tentative evidence that IL13 SNPs in the coding region may be of significance in COPD susceptibility.

Liver lobe torsion in three adult rabbits.

This paper describes three cases of liver lobe torsion in rabbits presenting with anorexia, lethargy, jaundice and abdominal pain. This condition was associated with anaemia and elevation of alanine aminotransferase, aspartate aminotransferase and gamma-glutamyl transferase. Abnormal radiological findings included hepatomegaly, gas-filled intestinal loops consistent with gastrointestinal ileus and ascites. Ultrasonographic findings included heterogeneous liver parenchyma, free abdominal fluid and reduced bowel motility. Diagnosis was confirmed by histopathological examination of the liver in all three cases.

Pharmacogenetic characterization of indacaterol, a novel beta 2-adrenoceptor agonist.

BACKGROUND AND PURPOSE: Indacaterol is a novel beta(2)-adrenoceptor agonist in development for the treatment of chronic obstructive pulmonary disease. The aim of this study was to investigate the comparative pharmacology of indacaterol in recombinant cells expressing the common polymorphic variants of the human beta(2)-adrenoceptor and in human primary airway smooth muscle (ASM) cells. EXPERIMENTAL APPROACH: Chinese hamster ovarian-K1 cell lines expressing high and low levels of the common human beta(2)-adrenoceptor variants were generated [Gly16-Glu27-Val34-Thr164(GEVT), RQVT, GQVT] and also the rare GQVI variant. Human primary ASM cells were isolated from explants of trachealis muscle. Adenosine-3',5'-cyclic-monophosphate production was used as an outcome measure. KEY RESULTS: In both the low- and high-expression recombinant GEVT 'wild type' cell lines indacaterol is a high-efficacy agonist. Salmeterol and formoterol were identified as low- and high-efficacy agonists, respectively, and showed similar potencies to indacaterol irrespective of the beta(2)-adrenoceptor genotype. The I164 variant cell line was associated with a reduced capacity to generate adenosine-3',5'-cyclic-monophosphate in response to beta(2)-adrenoceptor agonist. In the human primary ASM cells indacaterol gave a maximal response intermediate between that of salmeterol and formoterol. CONCLUSIONS AND IMPLICATIONS: These data demonstrate that indacaterol is a high-efficacy agonist in recombinant cell systems but acts with lower efficacy in human primary ASM cells. No marked genotype-dependent effects were observed for common variants; however, changes in I164 receptor activity were identified, which were dependent on the level of expression of beta(2)-adrenoceptors.

Leukotriene pathway genetics and pharmacogenetics in allergy.

Leukotrienes (LT) are biologically active lipid mediators known to be involved in allergic inflammation. Leukotrienes have been shown to mediate diverse features of allergic conditions including inflammatory cell chemotaxis/activation and smooth muscle contraction. Cysteinyl leukotrienes (LTC(4), LTD(4) and, LTE(4)) and the dihydroxy leukotriene LTB(4) are generated by a series of enzymes/proteins constituting the LT synthetic pathway or 5-lipoxygenase (5-LO) pathway. Their function is mediated by interacting with multiple receptors. Leukotriene receptor antagonists (LTRA) and LT synthesis inhibitors (LTSI) have shown clinical efficacy in asthma and more recently in allergic rhinitis. Despite growing knowledge of leukotriene biology, the molecular regulation of these inflammatory mediators remains to be fully understood. Genes encoding enzymes of the 5-LO pathway (i.e. ALOX5, LTC4S and LTA4H) and encoding for LT receptors (CYSLTR1/2 and LTB4R1/2) provide excellent candidates for disease susceptibility and severity; however, their role remains unclear. Preliminary data also suggest that 5-LO pathway/receptor gene polymorphism can predict patient responses to LTSI and LTRA; however, the exact mechanisms require elucidation. The aim of this review was to summarize the recent advances in the knowledge of these important mediators, focusing on genetic and pharmacogenetic aspects in the context of allergic phenotypes.

Positionally cloned asthma susceptibility gene polymorphisms and disease risk in the British 1958 Birth Cohort.

OBJECTIVE: The aim of this study was to estimate the contribution of polymorphisms in the positionally cloned asthma candidate genes ADAM33, PHF11, DPP10, GPRA and PTGDR to the risk of asthma, total and specific immunoglobulin E level, lung function and wheezing in a large, nationally representative, population. METHODS: An association analysis was undertaken using genotype data for tagging and previously associated single nucleotide polymorphisms (SNPs) in regions of these genes and longitudinal phenotype data from singletons of white ethnicity in the British 1958 Birth Cohort DNA archive (n = 7703). Population-attributable risk fractions for SNPs showing association were calculated. RESULTS: Polymorphisms producing small but statistically significant increases in asthma risk (OR 1.1 per allele) were identified in DPP10 and ADAM33, with the strongest evidence being for SNPs tagging the DPP10 gene. No individual SNP in any gene under study markedly increased risk for any of the phenotypes in the population studied. CONCLUSIONS: These data suggest that DPP10 and ADAM33 influence asthma risk in the UK population. However, the effects driven by any given locus are small, and genotyping of multiple polymorphisms in many genes will be needed to define a full genetic profile for disease risk.

The role of LTA4H and ALOX5AP polymorphism in asthma and allergy susceptibility.

BACKGROUND: Leukotrienes (LTs) have been identified as central mediators in asthma and allergy. Pharmacological inhibition of cysteinyl-LT activity improves asthma symptoms and control. Accumulating evidence suggests a role for the dihydroxy leukotriene LTB(4) in airway disease. LTA(4) hydrolase and 5-lipoxygenase activating protein have key roles in LTB(4) production. Single nucleotide polymorphism (SNPs) and haplotypes spanning the LTA4H and ALOX5AP genes have been associated with LTB(4) production and myocardial infarction (MI). OBJECTIVE: To assess the contribution of LTA4H and ALOX5AP polymorphism to asthma and allergy susceptibility. METHODS: Three hundred and forty-one Caucasian families (two asthmatic siblings) were genotyped for eight SNPs spanning ALOX5AP and five SNPs spanning LTA4H. Association analyses of asthma and related phenotypes (total IgE, atopy, bronchial hyper-responsiveness, FEV(1)) were undertaken using the Family Based Association Test. RESULTS: Single point analyses identified association (P < 0.05) between SNPs SG13S114, SG13S89, SG13S41 (ALOX5AP), rs1978331 (LTA4H) and asthma and/or related phenotypes. Haplotype analyses using all LTA4H SNPs identified a single key risk haplotype for the development of asthma (P = 0.006) and related phenotypes (P = 0.042-0.005). Haplotype analyses using all ALOX5AP SNPs identified several asthma and atopy risk and protective haplotypes. There was limited correlation with previously identified MI risk haplotypes in both genes. Carriers of both ALOX5AP SG13S41 and LTA4H rs1978331 alleles had an increased risk of developing asthma (OR 2.17, CI 1.41-3.32). CONCLUSIONS: These data provide evidence for the role of SNPs spanning the ALOX5AP and LTA4H genes in asthma and atopy susceptibility in the Caucasian population and support a role for LTB(4) in disease pathogenesis.

Pharmacogenetics and asthma: false hope or new dawn?

Pharmacogenetic approaches provide the opportunity to improve prescribing for asthmatic patients in order to optimise efficacy and prevent side-effects. Currently, there are comprehensive data available on the extent of genetic variation in the human genome that will further this area of research. However, less is known about the functional consequences of many of the identified polymorphisms in genes whose products may predict drug efficacy. In addition, there is a shortage of well-designed, adequately powered clinical studies in this area. This series summarises the current state of knowledge and identifies areas for further research.

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.