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Thompson MD, Capra V, Takasaki J, Maresca G, Rovati GE, Slutsky AS, Lilly C, Zamel N, McIntyre Burnham W, Cole DE, Siminovitch KA. A functional G300S variant of the cysteinyl leukotriene 1 receptor is associated with atopy in a Tristan da Cunha isolate. Pharmacogenet Genomics 2007; 17:539-49. [PMID: 17558309 DOI: 10.1097/fpc.0b013e328012d0bf] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Atopy is a well-defined immune phenotype that is reported to be a risk factor for asthma. Among the many loci that contribute to a genetic predisposition to asthma, the cysteinyl leukotriene receptor genes and their variants have been important subjects of study because they are functionally and pharmacologically implicated in the atopy phenotype affecting many asthma subjects. Moreover, the product of cysteinyl-leukotriene 1 receptor gene (CysLT1), located at Xq13.2, is targeted by LT receptor antagonists. In our earlier association study, the M201V variant of the cysteinyl-leukotriene 2 receptor gene (CysLT2), located at 13q14, was implicated in atopic asthma. Here we report the screening of the coding region of the CysLT1, gene in the highly asthmatic Tristan da Cunha population. In this population, we discovered a CysLT1 G300S variant that is carried with a significantly higher frequency in atopics and asthmatics from the Tristan da Cunha population. Furthermore, we report the asthma independent association of the CysLT1 G300S variant with atopy. Subsequently, we compared the changes conferred by each SNP on CysLT function. The CysLT1 300S receptor interacts with LTD4 with significantly greater potency. For the 300S variant, a statistically significant decrease in the effector concentration for half-maximum response (EC50) for intracellular Ca flux and total InsP generation is observed. Other aspects of the receptor function and activity, such as desensitization, pharmacologic profile in response to montelukast, and cellular localization, are unchanged. These in vitro analyses provide evidence that the 300S CysLT1 variant, found more commonly in atopics in the Tristan da Cunha population, encodes a functionally more sensitive variant.
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Affiliation(s)
- Miles D Thompson
- Laboratory Medicine, Banting Institute, Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada.
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52
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Grayson MH, Korenblat PE. The role of antileukotriene drugs in management of rhinitis and rhinosinusitis. Curr Allergy Asthma Rep 2007; 7:209-15. [PMID: 17448333 DOI: 10.1007/s11882-007-0074-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Antileukotriene drugs have been studied for more than 15 years. In this review we examine the role of leukotrienes in rhinitis and rhinosinusitis, and explore the clinical literature supporting the use of anti-leukotriene agents in these diseases. Although these medications clearly are efficacious in rhinitis, it is unclear where in the armamentarium they should be used. The evidence for use in sinusitis has not been well studied except in sinusitis-associated aspirin-exacerbated respiratory disease. In this circumstance there is information that allows use of antileukotriene agents to be considered efficacious. We provide our rationale for use and await future clinical studies to answer this important question.
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Affiliation(s)
- Mitchell H Grayson
- Division of Allergy and Immunology, Department of Internal Medicine, Washington University School of Medicine, Campus Box 8122, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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53
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Abstract
When activated by specific antigen, complement, or other transmembrane stimuli, mast cells (MCs) generate three eicosanoids: prostaglandin (PG)D(2), leukotriene (LT)B(4), and LTC(4), the parent molecule of the cysteinyl leukotrienes (cysLTs). These diverse lipid mediators, which are generated from a single cell membrane-associated precursor, arachidonic acid, can initiate, amplify, or dampen inflammatory responses and influence the magnitude, duration, and nature of subsequent immune responses. PGD(2) and cysLTs, which were originally recognized for their bronchoconstricting and vasoactive properties, also serve diverse and pivotal functions in effector cell trafficking, antigen presentation, leukocyte activation, matrix deposition, and fibrosis. LTB(4) is a powerful chemoattractant for neutrophils and certain lymphocyte subsets. Thus, MCs can contribute to each of these processes through eicosanoid generation. Additionally, MCs express G-protein-coupled receptors specific for cysLTs, LTB(4), and another eicosanoid, PGE(2). Each of these receptors can regulate MC functions in vivo by autocrine and paracrine mechanisms. This review focuses on the biologic functions for MC-associated eicosanoids, the regulation of their production, and the mechanisms by which eicosanoids may regulate MC function in host defense and disease.
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Affiliation(s)
- Joshua A Boyce
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
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Qiu Y, Zhu J, Bandi V, Guntupalli KK, Jeffery PK. Bronchial mucosal inflammation and upregulation of CXC chemoattractants and receptors in severe exacerbations of asthma. Thorax 2007; 62:475-82. [PMID: 17234659 PMCID: PMC2117215 DOI: 10.1136/thx.2006.066670] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND A study was undertaken to test the hypothesis that severe exacerbations of asthma are characterised by increased bronchial mucosal neutrophilia associated with upregulation of neutrophil chemoattractant ligands and their specific cell surface receptors. METHODS Immunohistology and in situ hybridisation were applied to endobronchial biopsy specimens from three groups: (1) 15 patients admitted to hospital with a severe exacerbation of asthma (E-asthma), (2) 15 with stable asthma (S-asthma) and (3) 15 non-atopic and non-smoker surgical controls (NSC). RESULTS There were significantly more neutrophils and eosinophils in the epithelium and subepithelium of patients in the E-asthma group (median (range) neutrophils 7 (0-380) and 78 (10-898)/mm2, eosinophils 31 (0-167) and 60 (6-351)/mm2, p<or=0.01 compared with NSC: 0 (0-10, 0-7, 0-18 and 0-3)/mm2, respectively), resulting in similar final densities of eosinophils and neutrophils. With respect to neutrophil chemoattractants and receptors, counts of CXCL5, CXCL8, CXCR1 and CXCR2 mRNA-positive cells in the subepithelium of the E-asthma group were, respectively, 5, 4, 4 and 18 times greater (p<or=0.01) than those of the NSC group. In the E-asthma group, cells expressing CXCL5 or CXCR2 were eightfold and threefold more frequent than those expressing CXCL8 or CXCR1 mRNA, respectively (p<0.01). CXCL5 and CXCR2 in E-asthma were associated with the number of eosinophils (r=0.59 and 0.66, p<0.02 for both) rather than the number of neutrophils. CONCLUSION In severe exacerbations of asthma there is a bronchial mucosal neutrophilia, eosinophilia and upregulation of CXC chemoattractants and their receptors. CXCL5 and CXCR2 have an association with eosinophila only, and these represent potentially new targets for treatment in exacerbations of asthma.
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Affiliation(s)
- Yusheng Qiu
- Lung Pathology, Department of Gene Therapy, Imperial College, and Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK
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Grayson MH, Korenblat PE. Treating asthma in the older patient: is there a place for leukotriene modifiers? Drugs Aging 2006; 23:451-9. [PMID: 16872230 DOI: 10.2165/00002512-200623060-00002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Asthma is a common airway disease found in people of all ages, although most studies of asthma therapies are focused on adolescent and young adults. Little information exists on the use of asthma therapeutics in the older patient (>65 years of age). The newest therapeutic class to be released in the US for the treatment of asthma is the leukotriene modifiers. These medications (either receptor antagonists or enzyme inhibitors) have been found to be beneficial in younger patients with asthma, but their potential role in older patients is less clear. In this review, the data regarding the use of these medications in older patients are examined, as are the epidemiological and pathophysiological issues regarding asthma in this growing patient population. On the basis of the two published reports of leukotriene modifiers in the older patient, we conclude that leukotriene modifiers are useful in this population, but like other controller therapies for asthma, they are less effective in the older population.
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Affiliation(s)
- Mitchell H Grayson
- Division of Allergy and Immunology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Abstract
BACKGROUND While we have international guidelines and various national guidelines for asthma diagnosis and management, asthma remains poorly controlled in many children and adults. In this paper we review the limitations of current asthma guidelines and describe important issues and remaining questions regarding asthma guidelines for use, particularly in primary care. DISCUSSION Clinical practice guidelines based on evidence from randomized controlled trials are considered the most rigorous and accurate. Current evidence-based guidelines are written predominantly from the perspective of the patient with a clear-cut asthma diagnosis, however, and tend not to consider the heterogeneity of asthma or to accommodate individual patient variations in response to treatment or their needs, differences in practice settings, or local differences in availability and cost of therapies. The results of randomized controlled trials, which are designed to establish efficacy of treatment under ideal conditions, may not apply to 'real-world' clinical practice, where patients are unselected, monitoring is less frequent, and effectiveness--the benefit of treatment in routine clinical practice--is the most relevant outcome. Moreover, most guidelines see asthma in isolation rather than considering other factors that may impact on asthma and response to asthma therapy, particularly age, allergic rhinitis, cigarette smoking, adherence, and genetic factors. When these links are recognized, guidelines rarely provide practical recommendations for treatment in these scenarios. Finally, there is some evidence that general practitioners are not convinced of the applicability of asthma guidelines to their practice settings, especially when those writing the guidelines principally work in specialist practice. CONCLUSION Developing country-specific guidelines or, ideally, local guidelines could provide more practical solutions for asthma care and could account for regional factors that influence patient choice and adherence to therapy. Pragmatic clinical trials and well-designed observational trials are needed in addition to randomized controlled trials to assess real-world effectiveness of therapies, and such evidence needs also to be considered by guideline writers. Finally, practical tools to facilitate the diagnosis and assessment of asthma and factors responsible for poor control, such as associated allergic rhinitis, limited adherence, and smoking behavior, are needed to supplement treatment information provided in clinical practice guidelines for asthma.
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MESH Headings
- Adult
- Anti-Allergic Agents/therapeutic use
- Anti-Asthmatic Agents/therapeutic use
- Asthma/diagnosis
- Asthma/epidemiology
- Asthma/genetics
- Asthma/therapy
- Causality
- Child
- Comorbidity
- Evidence-Based Medicine/methods
- Genetic Predisposition to Disease
- Global Health
- Humans
- Patient Compliance
- Practice Guidelines as Topic
- Rhinitis, Allergic, Perennial/diagnosis
- Rhinitis, Allergic, Perennial/epidemiology
- Rhinitis, Allergic, Perennial/therapy
- Rhinitis, Allergic, Seasonal/diagnosis
- Rhinitis, Allergic, Seasonal/epidemiology
- Rhinitis, Allergic, Seasonal/therapy
- Smoking/epidemiology
- Smoking Prevention
- Treatment Outcome
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Affiliation(s)
- David Price
- Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Westburn Road, Aberdeen AB25 2AY, UK
| | - Mike Thomas
- Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Westburn Road, Aberdeen AB25 2AY, UK
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Jeffery PK, Haahtela T. Allergic rhinitis and asthma: inflammation in a one-airway condition. BMC Pulm Med 2006; 6 Suppl 1:S5. [PMID: 17140423 PMCID: PMC1698498 DOI: 10.1186/1471-2466-6-s1-s5] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background Allergic rhinitis and asthma are conditions of airway inflammation that often coexist. Discussion In susceptible individuals, exposure of the nose and lungs to allergen elicits early phase and late phase responses. Contact with antigen by mast cells results in their degranulation, the release of selected mediators, and the subsequent recruitment of other inflammatory cell phenotypes. Additional proinflammatory mediators are released, including histamine, prostaglandins, cysteinyl leukotrienes, proteases, and a variety of cytokines, chemokines, and growth factors. Nasal biopsies in allergic rhinitis demonstrate accumulations of mast cells, eosinophils, and basophils in the epithelium and accumulations of eosinophils in the deeper subepithelium (that is, lamina propria). Examination of bronchial tissue, even in mild asthma, shows lymphocytic inflammation enriched by eosinophils. In severe asthma, the predominant pattern of inflammation changes, with increases in the numbers of neutrophils and, in many, an extension of the changes to involve smaller airways (that is, bronchioli). Structural alterations (that is, remodeling) of bronchi in mild asthma include epithelial fragility and thickening of its reticular basement membrane. With increasing severity of asthma there may be increases in airway smooth muscle mass, vascularity, interstitial collagen, and mucus-secreting glands. Remodeling in the nose is less extensive than that of the lower airways, but the epithelial reticular basement membrane may be slightly but significantly thickened. Conclusion Inflammation is a key feature of both allergic rhinitis and asthma. There are therefore potential benefits for application of anti-inflammatory strategies that target both these anatomic sites.
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Affiliation(s)
- Peter K Jeffery
- Lung Pathology, Imperial College at the Royal Brompton Hospital, London, SW3 6NP, UK
| | - Tari Haahtela
- Skin and Allergy Hospital, Helsinki University Central Hospital, PO Box 160, 00029 HUS, Finland
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Kelly MM, Chakir J, Vethanayagam D, Boulet LP, Laviolette M, Gauldie J, O'Byrne PM. Montelukast treatment attenuates the increase in myofibroblasts following low-dose allergen challenge. Chest 2006; 130:741-53. [PMID: 16963671 DOI: 10.1378/chest.130.3.741] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
RATIONALE Airway remodeling is believed to be important in the pathophysiology of asthma, and myofibroblasts are increased in the airways of asthmatic individuals 24 h after allergen challenge. Leukotriene receptor antagonists exert antiinflammatory activity in asthma, but it is unknown whether they influence indices of airway remodeling. In the present study, we evaluated the effect of montelukast on airway myofibroblasts following low-dose allergen challenge (LDAC). METHODS Stable subjects with mild asthma were included in a two-center, randomized, parallel-group study. A 2-week run-in period was followed by LDAC and endobronchial biopsy. Subjects were then randomized to receive either montelukast, 10 mg/d, or placebo (n = 10 in each group) for 8 weeks in a double-blind manner; at the end of the treatment period, subjects underwent a second LDAC and endobronchial biopsy. The effect of treatment on myofibroblasts, fibroblasts, and inflammatory cells was examined using electron microscopy techniques. RESULTS Treatment with montelukast showed no significant difference by comparison with placebo but did show a significant within-group treatment-related decrease in airway wall myofibroblasts not seen in the placebo group. In addition, the montelukast-treated group also showed a significant within-group reduction in lymphomononuclear cells and increased neutrophils. CONCLUSIONS The results suggest that montelukast has an inhibitory effect on airway structural cells that play a key role in airway remodeling in allergic airway inflammation, and that montelukast may be a useful therapy to attenuate airway remodeling in asthma.
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Affiliation(s)
- Margaret M Kelly
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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Jiang Y, Kanaoka Y, Feng C, Nocka K, Rao S, Boyce JA. Cutting Edge: Interleukin 4-Dependent Mast Cell Proliferation Requires Autocrine/Intracrine Cysteinyl Leukotriene-Induced Signaling. THE JOURNAL OF IMMUNOLOGY 2006; 177:2755-9. [PMID: 16920908 DOI: 10.4049/jimmunol.177.5.2755] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Reactive mastocytosis (RM) in epithelial surfaces is a consistent Th2-associated feature of allergic disease. RM fails to develop in mice lacking leukotriene (LT) C4 synthase (LTC4S), which is required for cysteinyl leukotriene (cys-LT) production. We now report that IL-4, which induces LTC4S expression by mast cells (MCs), requires cys-LTs, the cys-LT type 1 receptor (CysLT1), and Gi proteins to promote MC proliferation. LTD4 (10-1000 nM) enhanced proliferation of human MCs in a CysLT1-dependent, pertussis toxin-sensitive manner. LTD4-induced phosphorylation of ERK required transactivation of c-kit. IL-4-driven comitogenesis was likewise sensitive to pertussis toxin or a CysLT1-selective antagonist and was attenuated by treatment with leukotriene synthesis inhibitors. Mouse MCs lacking LTC4S or CysLT1 showed substantially diminished IL-4-induced comitogenesis. Thus, IL-4 induces proliferation in part by inducing LTC4S and cys-LT generation, which causes CysLT1 to transactivate c-kit in RM.
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Affiliation(s)
- Yongfeng Jiang
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
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60
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Abstract
With the completion of the human genome project, many investigators are striving to translate the resulting wealth of new information into new and improved clinical practices. Pharmacogenomics represents one of the most promising of these applications for adult- and pediatric-based therapies. This article provides a historical perspective, but most importantly, uses this background to illustrate important principles of the field. The application of pharmacogenomics to asthma therapy is presented as an example of the current status of pharmacogenomics as it is being applied to an important pediatric health problem. Finally, a discussion of future promises and challenges to the application of pharmacogenomics is presented, including economic and ethical issues.
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Affiliation(s)
- Ronald N Hines
- Department of Pediatrics, Section of Clinical Pharmacology, Pharmacogenetics and Teratology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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