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Doyen V, Gautrin D, Vandenplas O, Malo JL. Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight. Expert Rev Clin Immunol 2024; 20:635-653. [PMID: 38235552 DOI: 10.1080/1744666x.2024.2306885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 01/15/2024] [Indexed: 01/19/2024]
Abstract
INTRODUCTION The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms. AREAS COVERED The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents. EXPERT OPINION Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.
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Affiliation(s)
- Virginie Doyen
- Department of Chest Medicine, Centre Hospitalier Universitaire UCL Namur, Université Catholique de Louvain, Yvoir, Belgium
| | - Denyse Gautrin
- Université de Montréal and Hôpital du Sacré-Cœur de Montréal, Montréal, Canada
| | - Olivier Vandenplas
- Department of Chest Medicine, Centre Hospitalier Universitaire UCL Namur, Université Catholique de Louvain, Yvoir, Belgium
| | - Jean-Luc Malo
- Université de Montréal and Hôpital du Sacré-Cœur de Montréal, Montréal, Canada
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Demange V, Zmirou-Navier D, Bohadana A, Wild P. Do airway inflammation and airway responsiveness markers at the start of apprenticeship predict their evolution during initial training? A longitudinal study among apprentice bakers, pastry makers and hairdressers. BMC Pulm Med 2018; 18:113. [PMID: 29996808 PMCID: PMC6042364 DOI: 10.1186/s12890-018-0674-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 06/13/2018] [Indexed: 11/15/2022] Open
Abstract
Background The natural history of airway inflammation and symptoms in occupations at risk of asthma is still not fully understood. We aimed to study the evolution during apprenticeship of inflammation markers, bronchial hyperresponsiveness (BHR) and symptoms in at-risk subgroups as defined from measurements of markers made shortly after the start of training. Methods Respiratory symptoms, FEV1 and airway resistance post-bronchial challenge (MBC) test results, fractional exhaled nitric oxide (FeNO) measurements, and eosinophils in nasal lavage fluid were investigated in apprentice bakers, pastry-makers and hairdressers. Four visits were conducted: at the start of the training and every six months thereafter. Four baseline risk groups were defined, based on, (i) a high level of FeNO (NO), (ii) eosinophils > 1% (Eosino), (iii) a ≥ 15% decrease in FEV1 during the MBC test (HR), and (iv) a ≥ 50% increase in the resistance (Resist). The statistical analysis relied on mixed models. Results At baseline, the inflammation markers were related to the MBC markers. There was no evidence to suggest that the baseline risk groups predict a differential evolution of the airway inflammation and bronchial responsiveness markers, or the asthma-like symptoms considered. The baseline risk groups defined from MBC test predicted the levels of MBC markers. Similarly, the baseline risk groups based on eosinophilic inflammation predicted the levels of markers for eosinophilia. These results were similar in the three training tracks, with the exception of the FeNO levels which were not different according to the Eosino risk group. Twelve possible new asthma cases were identified, only the HR risk group predicted their occurrence. Conclusions Among this young population, at-risk groups based on initial high levels of inflammation markers did not experience any worsening during the follow-up. However, initial BHR predicted consistently high levels of all markers considered and occurrence of possible asthma. Electronic supplementary material The online version of this article (10.1186/s12890-018-0674-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Valérie Demange
- Institut National de Recherche et de Sécurité (INRS), 1 rue du Morvan, 54519, Vandoeuvre-les-Nancy, France.
| | - Denis Zmirou-Navier
- School of Public Health (EHESP), 15 avenue du Professeur Léon-Bernard, 35043, Rennes Cedex, France
| | - Abraham Bohadana
- Pulmonary Institute, Shaare Zedek Medical Center, 12 Baiyt Street, 91031, Jerusalem, Israel
| | - Pascal Wild
- Institut National de Recherche et de Sécurité (INRS), 1 rue du Morvan, 54519, Vandoeuvre-les-Nancy, France
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Talini D, Novelli F, Bacci E, Dente FL, De Santis M, Di Franco A, Melosini L, Vagaggini B, Paggiaro PL. Comparison between Airway Responses to High versus Low Molecular Weight Compounds in Occupational Asthma. J Allergy (Cairo) 2011; 2011:781470. [PMID: 21747871 PMCID: PMC3124963 DOI: 10.1155/2011/781470] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 03/29/2011] [Indexed: 11/19/2022] Open
Abstract
Occupational asthma (OA) is a heterogeneous disease, and the characteristics of the sensitizer responsible for OA may induce different clinical, functional, and biological manifestations. We examined the characteristics of 74 patients with OA induced by low molecular weight compounds (LMWC) or by high molecular weight compounds (HMWC) and diagnosed by specific inhalation challenge (SIC). Patients with OA induced by LMWC had a longer occupational exposure before the beginning of symptoms, a lower sputum eosinophilia, and a higher prevalence of late airway response (LAR), in comparison with patients with OA induced by HMWC. Pulmonary function tended to be poorer and atopy tended to be less frequent in LMWC-induced OA than in HMWC-induced OA. These data confirm and extend previous observations showing that the characteristics of the specific sensitizer inducing OA may determine different clinical, functional, and biological features, probably related to the difference pathogenetic mechanisms underlying these different types of OA.
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Affiliation(s)
- D. Talini
- Occupational Health Unit, Prevention Department, Galleria Gerace 14, 56126 Pisa, Italy
| | - F. Novelli
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - E. Bacci
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - F. L. Dente
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - M. De Santis
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - A. Di Franco
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - L. Melosini
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - B. Vagaggini
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
| | - P. L. Paggiaro
- Cardio-Thoracic and Vascular Department, University of Pisa, 56126 Pisa, Italy
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Holness DL, Tabassum S, Tarlo SM, Liss GM, Silverman F, Manno M. Practice Patterns of Pulmonologists and Family Physicians for Occupational Asthma. Chest 2007; 132:1526-31. [PMID: 17890481 DOI: 10.1378/chest.06-2224] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND The longer the duration of symptoms of occupational asthma (OA) before diagnosis, the poorer the outcome. Physicians can play a key role in the early recognition of occupational lung diseases (OLDs), including OA. Our objective was to document and compare the practice patterns, barriers, and needs for early diagnosis of OA among pulmonologists and family physicians. METHODS Based on information from the literature and interviews with pulmonologists and family physicians, a survey was developed to obtain information on practice patterns. The survey was sent to all pulmonologists and a random sample of 600 family physicians in Ontario. RESULTS Eight percent of pulmonologists and 7% of family physicians report seeing >20 patients a year with OLD. The majority report taking a workplace exposure history. The most commonly stated barrier to obtaining a workplace exposure history was time constraints. Main reasons for referral to specialists for diagnosis include personal lack of expertise, testing facilities, and knowledge about workers' compensation, while lack of timely access to specialists is a barrier for referral. While most physicians identified a need for further education, those who did not identify a need for further occupational respiratory education cited low volume of patients, access to specialists, and time constraints as reasons for not wanting further education. CONCLUSIONS Opportunities are identified to improve health services delivery and educational initiatives for OA, with approaches tailored to each particular physician group.
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Affiliation(s)
- D Linn Holness
- Gage Occupational and Environmental Health Unit, St Michael's Hospital, University of Toronto, ON, Canada M5B 1W8.
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Sumi Y, Foley S, Daigle S, L'Archevêque J, Olivenstein R, Letuvé S, Malo JL, Hamid Q. Structural changes and airway remodelling in occupational asthma at a mean interval of 14 years after cessation of exposure. Clin Exp Allergy 2007; 37:1781-7. [PMID: 17900308 DOI: 10.1111/j.1365-2222.2007.02828.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Occupational asthma (OA) may cause alterations of airways with inflammation and remodelling after cessation of exposure. Although the long-term clinical, functional and induced sputum sequelae have been examined in workers removed from exposure, the long-term pathological outcomes are unknown. OBJECTIVE We aimed to investigate whether airway inflammation and remodelling were present in bronchial biopsies of subjects with prior OA but without evidence of persisting asthma at a mean interval of 14 years after cessation of exposure. METHODS Ten clinically and functionally asymptomatic subjects with a prior diagnosis of OA were recruited and underwent bronchoscopy, bronchoalveolar lavage and bronchial biopsy. Comparisons were made with biopsies from normal control subjects. Epithelial detachment, epithelial metaplasia, mucous gland and airway smooth muscle (ASM) areas as well as the distance between the epithelium and ASM were measured by image analysis. The amount of collagen present was assessed by van Gieson staining. The numbers of TGF-beta1- and eosinophil cationic protein (ECP)-positive cells were evaluated by specific immunostaining. RESULTS Statistically significant increases were found in the numbers of TGF-beta1- and ECP-positive cells and in the amount of subepithelial fibrosis present in the biopsies of subjects with prior OA compared with control biopsies. The distance between the epithelium and ASM was significantly reduced in the OA group. Increases in epithelial metaplasia, ASM mass, mucous gland numbers, collagen deposition and eosinophilia in the OA group were not statistically significant. There was no evidence of ongoing inflammation in the group with prior OA as assessed by the number of T lymphocytes present. CONCLUSION Some aspects of airway inflammation and remodelling persist in subjects with prior OA long after cessation of exposure even in the absence of clinical, sputum and functional abnormalities. These findings are relevant to the assessment of long-term sequelae in subjects with OA when reviewed after cessation of exposure.
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Affiliation(s)
- Y Sumi
- Meakins-Christie Laboratories, McGill University, Montreal, QC, Canada
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Winck J. Pneumonite de hipersensibilidade: A experiência portuguesa. REVISTA PORTUGUESA DE PNEUMOLOGIA 2005. [DOI: 10.1016/s0873-2159(15)30547-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Abstract
Substantial epidemiologic and clinical evidence indicates that agents inhaled at work can induce asthma. In industrialized countries, occupational factors have been implicated in 9 to 15% of all cases of adult asthma. Work-related asthma includes (1) immunologic occupational asthma (OA), characterized by a latency period before the onset of symptoms; (2) nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritant materials; (3) work-aggravated asthma, which is preexisting or concurrent asthma exacerbated by workplace exposures; and (4) variant syndromes. Assessment of the work environment has improved, making it possible to measure concentrations of several high- and low-molecular-weight agents in the workplace. The identification of host factors, polymorphisms, and candidate genes associated with OA is in progress and may improve our understanding of mechanisms involved in OA. A reliable diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and treatment with inhaled glucocorticoids lead to a better outcome. Finally, strategies for preventing OA should be implemented and their cost-effectiveness examined.
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Affiliation(s)
- Cristina E Mapp
- Section of Hygiene and Occupational Medicine, Department of Clinical and Experimental Medicine, University of Ferrara, Italy.
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Maestrelli P. Natural history of adult-onset asthma: insights from model of occupational asthma. Am J Respir Crit Care Med 2004; 169:331-2. [PMID: 14739131 DOI: 10.1164/rccm.2312012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Maghni K, Lemière C, Ghezzo H, Yuquan W, Malo JL. Airway Inflammation after Cessation of Exposure to Agents Causing Occupational Asthma. Am J Respir Crit Care Med 2004; 169:367-72. [PMID: 14578217 DOI: 10.1164/rccm.200309-1238oc] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Subjects with occupational asthma (OA) generally present asthma symptoms and airway hyperresponsiveness after cessation of exposure. We hypothesized that they are also left with airway inflammation. We assessed 133 subjects with OA at a mean interval of 8.7 years (0.5-20.8 years) after cessation of exposure by questionnaire, airway caliber, and responsiveness to methacholine. Satisfactory samples of induced sputum were obtained from 98 subjects. We defined three groups of subjects: (1) cured: normalization of the concentration of methacholine provoking a 20% decrease in FEV1 (PC20), (2) improved: increase in PC20 by 3.2-fold or more but PC20 still abnormal, and (3) not improved: no significant change in PC20. In all, 9/28 subjects (32.1%) with no improvement versus 6/56 (10.7%) subjects with partial and complete improvements had sputum eosinophils equal to or greater than 2% and 11/28 (39.3%) subjects versus 11/56 (19.6%) subjects showed sputum neutrophils equal to or greater than 61%. Levels of interleukin-8 and of the neutrophil-derived myeloperoxidase were significantly more elevated in sputum of subjects with no improvement. Those in the cured or improved groups had a significantly longer time lapse since diagnosis and a higher PC20 at the time of diagnosis. We conclude that failure to improve after cessation of exposure to an agent causing OA is associated with airway inflammation at follow-up.
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Affiliation(s)
- Karim Maghni
- Department of Chest Medicine, Sacré-Coeur Hospital, Montreal, Quebec, Canada
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12
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Chan-Yeung M, Malo JL, Tarlo SM, Bernstein L, Gautrin D, Mapp C, Newman-Taylor A, Swanson MC, Perrault G, Jaques L, Blanc PD, Vandenplas O, Cartier A, Becklake MR. Proceedings of the first Jack Pepys Occupational Asthma Symposium. Am J Respir Crit Care Med 2003; 167:450-71. [PMID: 12554630 DOI: 10.1164/rccm.167.3.450] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
The workplace can be responsible for approximately one in 10 cases of adult-onset asthma. Two types of occupational asthma (OA) are distinguished by whether they arise after a latency period that is necessary for acquiring sensitization or as a result of acute exposure to irritant materials (irritant-induced asthma). The pathophysiology of OA with a latency period is similar to that of nonoccupational asthma, whereas the mechanism of irritant-induced asthma is still uncertain. HLA haplotypes and other genetic polymorphisms have been found to be associated with OA. According to various sources of data, the overall frequency of OA has remained stable in the last 10 years, although the frequency of causal agents vary. Registers of causal occupations and agents have been issued on Web sites (eg, www.asmanet.com ). Improved sampling methods have shown that the degree of exposure plays a key role in the onset of the disease, whereas prospective data collected in high-risk workplaces have also identified personal risk factors (eg, atopy, smoking, and rhinoconjunctivitis). A diagnosis of OA should no longer be based on a compatible history only but should be confirmed by means of objective testing. Once the diagnosis is confirmed, the worker should be removed from exposure, and satisfactory compensation programs should be offered, the most important being retraining programs with financial compensations because affected workers are generally young. The cost-effectiveness of prevention programs in high-risk workforces should be assessed.
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Affiliation(s)
- J L Malo
- Department of Respiratory Medicine, Sacré-Coeur Hospital, Montreal, Quebec, Canada
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Boulet LP, Turcotte H, Laviolette M, Naud F, Bernier MC, Martel S, Chakir J. Airway hyperresponsiveness, inflammation, and subepithelial collagen deposition in recently diagnosed versus long-standing mild asthma. Influence of inhaled corticosteroids. Am J Respir Crit Care Med 2000; 162:1308-13. [PMID: 11029336 DOI: 10.1164/ajrccm.162.4.9910051] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This study aimed at documenting airway inflammation and subepithelial collagen deposition in patients using only inhaled beta(2)-agonists with either recently diagnosed asthma (RDA: </= 2 yr, n = 16) or long-standing asthma (LSA: >/= 13 yr, n = 16) and at the influence of an intense inhaled corticosteroid (ICS) treatment on these parameters, in relation to changes in airway responsiveness. Patients had a methacholine inhalation test and a bronchoscopy with bronchial biopsies before and after an 8-wk treatment with inhaled fluticasone propionate (FP), 1,000 microgram/day. Baseline FEV(1) (mean +/- SEM) was normal and similar in both groups (RDA: 98.1 +/- 2.7, LSA: 94.5 +/- 4.6%). Geometric mean methacholine PC(20) was lower in LSA than in RDA (0.44 versus 3.37 mg/ml) at baseline and improved similarly by 1.85 and 1.86 double concentrations with FP treatment. PC(20) normalized (>/= 16 mg/ml) in five patients with RDA and two patients with LSA. Baseline mean bronchial cell counts (per mm(2) connective tissue surface) for CD3(+), CD4(+), CD8(+), CD25(+), EG1(+), CD45ro(+), and AA1(+) cells were similar in both groups. With FP, EG1(+) (p < 0.001), EG2(+) (p = 0.018), and AA1(+) counts (p = 0.009) decreased significantly in both groups while CD45ro(+) (p = 0.02) counts decreased only in LSA. Baseline type 1 and type 3 collagen deposition underneath the basement membrane was similar in RDA and LSA and did not change significantly after FP. This study shows that recent compared to long-standing mild asthma is associated with a similar degree of airway inflammation and subepithelial fibrosis, and a similar improvement in airway hyperresponsiveness after 8 wk on high-dose ICS. It also indicates that once asthma becomes symptomatic, airway responsiveness cannot normalize in most subjects over such a time period, even with a high dose of ICS.
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Affiliation(s)
- L P Boulet
- Institut de Cardiologie et de Pneumologie de L'Université Laval, H opital Laval, Sainte-Foy, Québec, Canada.
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Bousquet J, Jeffery PK, Busse WW, Johnson M, Vignola AM. Asthma. From bronchoconstriction to airways inflammation and remodeling. Am J Respir Crit Care Med 2000; 161:1720-45. [PMID: 10806180 DOI: 10.1164/ajrccm.161.5.9903102] [Citation(s) in RCA: 1204] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- J Bousquet
- Clinique des Maladies Respiratoires and INSERM U454, Hopital Arnaud de Villeneuve, Montpellier, France
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Larouch V, Rivard G, Deschesnes F, Goulet R, Turcotte H, Boulet LP. Asthma and airway hyper-responsiveness in adults who required hospital admission for bronchiolitis in early childhood. Respir Med 2000; 94:288-94. [PMID: 10783941 DOI: 10.1053/rmed.1999.0748] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Viral respiratory infections in infancy may contribute to the development of airway hyper-responsiveness (AHR) in childhood but their effects on respiratory function at the adult age are still uncertain. A group of 42 subjects aged 17-35 with a pediatrician-made diagnosis of severe bronchiolitis in infancy (Br) were compared for the presence of asthma and AHR to a control group (C) paired for age and gender, without evidence of lower respiratory disease in infancy. All had a respiratory and environmental questionnaire, allergy skin prick tests, blood eosinophil count, total serum IgE determination and measurements of expiratory flows and airway response to methacholine. In Br and C groups, respectively, 38 and 12% of subjects had a physician-made diagnosis of asthma, 26 and 7% used bronchodilators and 12 and 0% an inhaled corticosteroid; 71 and 67%, respectively, were atopic, 50 and 24% were smokers and 43 and 17% had a first-degree relative with asthma. Mean baseline FEV1 and FEV1/FVC ratio were lower in the Br than in the C group, with 94/103% (P=0.002) and 80/87 (P<0.0001) of the predicted value, respectively. Geometric mean PC20 methacholine was significantly lower in the Br than in the C group 3.9/20.3 mg ml(-1) (P<0.0001). Mean blood eosinophil count and serum IgE levels were similar in both groups (P> 0.05). In conclusion, asthma and AHR were found more frequently in young adults with a past history of bronchiolitis, suggesting that this type of respiratory infection may contribute to altered pulmonary function in adulthood, although it may also represent an early manifestation of asthma. The influence of potential confounding factors, such as familial predisposition and exposure to cigarette smoke on the development of asthma and AHR in the Br group, cannot be excluded.
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Affiliation(s)
- V Larouch
- Unité de Recherche, Centre de Pneumologie, Hĵpital Laval, Université Laval, Sainte-Foy, Québec, Canada
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Chan-Yeung M, Obata H, Dittrick M, Chan H, Abboud R. Airway inflammation, exhaled nitric oxide, and severity of asthma in patients with western red cedar asthma. Am J Respir Crit Care Med 1999; 159:1434-8. [PMID: 10228107 DOI: 10.1164/ajrccm.159.5.9807007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Examination of induced sputum and measurement of exhaled NO have been advocated as noninvasive methods of assessing the degree of airway inflammation. In this study, we performed follow-up evaluation on 71 subjects with asthma caused by exposure to Western red cedar; 50 subjects had left exposure, whereas the rest continued to work in the same job. Spirometry, methacholine challenge tests, exhaled nitric oxide, and sputum induction were carried out. Of the 50 subjects who left exposure, 12 had no respiratory impairment according to the American Throacic Society guidelines for assessing respiratory impairment in patients with asthma, 17 belonged to Class 1, 12 to Class 2, five to Class 3, and four to Class 4. The percentage of eosinophils in induced sputum showed a significant inverse relationship with FEV1 (r = -0.46, p < 0.001), and a significant positive correlation with levels of exhaled NO (r = 0.42, p < 0.001) and with the class of respiratory impairment (r = 0.52, p < 0.001). Mean percent eosinophils were 1.5 for impairment Class 0, 2.2 for Class 1, 1.7 for Class 2, 6.8 for Class 3, and 16.3 for Class 4. No relationship was found between the levels of exhaled NO and the functional parameters as well as the impairment class. NO levels in ppb were 21 for impairment Class 0, 30 for Class 1, 22 for Class 2, 26 for Class 3, and 49 for Class 4. This study also provides objective evidence that airway inflammation, as indicated by induced sputum, corroborates the rating of respiratory impairment in patients with asthma.
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Affiliation(s)
- M Chan-Yeung
- The Respiratory Division, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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Affiliation(s)
- S Quirce
- Servicio de Alergología, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Spain
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Di Franco A, Vagaggini B, Bacci E, Bartoli ML, Cianchetti S, Carnevali S, Dente FL, Giannini D, Macchioni P, Ruocco L, Paggiaro PL. Leukocyte counts in hypertonic saline-induced sputum in subjects with occupational asthma. Respir Med 1998; 92:550-7. [PMID: 9692121 DOI: 10.1016/s0954-6111(98)90307-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We measured markers of eosinophilic inflammation in the blood and in the sputum induced by hypertonic saline (HS) inhalation of 24 subjects with occupational asthma who were still exposed to high molecular weight compounds (HMWCs, n = 8) or to low molecular weight compounds (LMWCs, n = 16); all subjects were symptomatic and showed bronchial hyperresponsiveness to methacholine at the time of study. Sputum cell counts were also measured in 14 normal subjects and in 24 subjects with non-occupational asthma with asthma severity similar to that of occupational asthmatics. Both occupational and non-occupational asthmatic subjects showed higher neutrophil percentages in HS-induced sputum than normal subjects, asthmatics with LMWC-induced asthma showing the highest values. Eosinophil percentages in HS-induced sputum were higher in non-occupational asthmatics and in asthmatics with HMWC-induced asthma than in normal subjects and in subjects with occupational asthma due to LMWCs. No difference in bronchial responsiveness, peak expiratory flow variability and serum eosinophil cationic protein (ECP) levels were observed among the different asthma groups. Although sputum eosinophil percentages significantly correlated with blood eosinophil percentages, sputum allowed the detection of a higher number of subjects with eosinophilic inflammation than blood. Serum ECP levels were normal in most asthmatic subjects. A significant correlation between sputum eosinophil percentages and bronchial hyperresponsiveness to HS was observed. Despite a similar degree of functional abnormalities, subjects with asthma due to LMWCs and still exposed to the occupational sensitizer showed a lower degree of eosinophilic inflammation and a higher degree of neutrophilic inflammation in the airways than subjects with occupational asthma due to HMWCs or non-occupational asthmatics. Furthermore, sputum eosinophil counts detect, better than blood indices, the degree of airway inflammation in both occupational and non-occupational asthma.
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Affiliation(s)
- A Di Franco
- 2nd Institute of Internal Medicine, University of Pisa, Italy
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Mapp CE, Balboni A, Baricordi R, Fabbri LM. Human leukocyte antigen associations in occupational asthma induced by isocyanates. Am J Respir Crit Care Med 1997; 156:S139-43. [PMID: 9351595 DOI: 10.1164/ajrccm.156.4.12-t-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Exposure to diisocyanates is recognized as a leading cause of occupational asthma. Occupational asthma induced by isocyanates shares many characteristics with immunoglobulin E (IgE)-mediated asthma: in both, the responsible agent is known, and the clinical presentation, response to inhalation challenge in the laboratory, and response to antiasthma drugs are similar. Although asthma mediated by an IgE mechanism occurs in atopic subjects, occupational asthma induced by isocyanates occurs mostly in nonatopic asthmatics, and an IgE-mediated mechanism has not been consistently demonstrated. However, activated T lymphocytes, methacromatic cells, and eosinophils are increased in the bronchial mucosa of allergic and nonallergic asthmatics and subjects with occupational asthma induced by isocyanates, suggesting similar, probably immunologically mediated mechanisms for both nonoccupational and occupational asthma. Occupational asthma occurs in up to 5-10% of the exposed subjects. Evaluation of major histocompatibility complex (MHC) class II genes in exposed subjects who develop toluene diisocyanate (TDI) asthma has shown a negative association with HLA-DQB1*0501 and a positive association with HLA-DQB1*0503 alleles. In addition, a high proportion of TDI asthmatics express the HLA-DQB1*0503-associated aspartic acid at residue 57, suggesting that HLA-DQ may have a key role in conferring susceptibility. Thus, asthma induced by the low-molecular-weight agent TDI may result from an immunologic reaction due to the interaction of genetic susceptibility with exposure in the workplace.
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Affiliation(s)
- C E Mapp
- Institute of Occupational Medicine, University of Padova, Italy
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Boulet LP, Laviolette M, Turcotte H, Cartier A, Dugas M, Malo JL, Boutet M. Bronchial subepithelial fibrosis correlates with airway responsiveness to methacholine. Chest 1997; 112:45-52. [PMID: 9228356 DOI: 10.1378/chest.112.1.45] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVES To evaluate the relationships between airway subepithelial collagen deposition and epithelial desquamation with airflow obstruction and hyperresponsiveness in different types of asthma and other respiratory conditions such as chronic cough and allergic rhinitis. DESIGN AND PARTICIPANTS We compared the histopathologic features observed on bronchial biopsy specimens obtained from 80 subjects: 38 with different types of asthma, 19 with chronic cough, 13 with allergic rhinitis, and 10 normal control subjects. Each subject had a questionnaire on respiratory symptoms and medication needs, measurements of expiratory flows and methacholine responsiveness, allergy skin prick tests, and a bronchoscopy with bronchial biopsies. None of the subjects studied used bronchial anti-inflammatory agents. RESULTS Different degrees of bronchial subepithelial fibrosis were present in asthmatic subjects, the most intense being observed in occupational asthma; a subepithelial deposition of collagen was also found in subjects with allergic rhinitis, although it was less intense than in asthma and irregularly distributed under the basement membrane. On global analysis, we found a significant correlation between individual provocative concentration of methacholine inducing a 20% fall in FEV1 (PC20) and subepithelial fibrosis intensity (rs=-0.70, p<0.001). The degree of epithelial desquamation was correlated with that of subepithelial fibrosis (rs=0.36, p=0.02) in subjects with normal airway responsiveness, but it was not correlated with the PC20 (rs=0.10, p>0.05). Neither the degree of subepithelial fibrosis nor epithelial desquamation was correlated with the FEV1. CONCLUSION These results suggest that structural airway changes such as subepithelial collagen deposition may be significant determinants or markers of a process that results in airway hyperresponsiveness.
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Affiliation(s)
- L P Boulet
- Centre québécois d'excellence en santé respiratoire: Unité de Recherche, Centre de Pneumologie de l'Hôpital Laval, Université Laval, Sainte-Foy, QC, Canada
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Affiliation(s)
- P Maestrelli
- Institute of Occupational Medicine, University of Padova, Italy
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Paré PD, Bai TR, Roberts CR. The structural and functional consequences of chronic allergic inflammation of the airways. CIBA FOUNDATION SYMPOSIUM 1997; 206:71-86; discussion 86-9, 106-10. [PMID: 9257006 DOI: 10.1002/9780470515334.ch5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Although asthma is generally considered a form of reversible airway obstruction, there is evidence that chronic allergic inflammation can lead to structural changes in the airway and a degree of progressive fixed airway obstruction. More importantly, these structural changes can lead to airway hyper-responsiveness. The structural consequences of chronic allergic inflammation are secondary to cellular proliferation and reorganization of the connective tissue constituents of the airway wall. Smooth muscle proliferation and hypertrophy may increase the potential for smooth muscle shortening against the elastic loads provided by lung parenchymal recoil and airway mucosal folding. Resident airway cells, as well as inflammatory cells, produce mediators, cytokines and growth factors that stimulate production of connective tissue proteins and proteoglycans that cause airway remodelling and altered mechanical function. Thickening of the airway wall internal to the smooth muscle layer can amplify the effect of smooth muscle shortening on airway calibre, and it could also stiffen the airway making it less distensible. Thickening of the airway wall external to the muscle can uncouple the airway from the distending force applied by the lung parenchyma. Early and aggressive anti-inflammatory medication may alter the natural history of asthma by preventing the structural changes that are a consequence of chronic allergic inflammation.
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Affiliation(s)
- P D Paré
- Respiratory Health Network of Centres of Excellence, University of British Columbia, Pulmonary Research Laboratory, St. Paul's Hospital, Vancouver, Canada
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Grammer LC, Shaughnessy MA. Study of employees with anhydride-induced respiratory disease after removal from exposure. J Occup Environ Med 1996; 38:771-4. [PMID: 8863202 DOI: 10.1097/00043764-199608000-00012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of this study was to determine the clinical and immunologic status of hexahydrophthalic anhydride (HHPA)-exposed employees who had developed an immunologic respiratory disease and who have been removed from exposure for at least 1 year. In a surveillance study spanning 4 years, we identified 28 employees with HHPA-induced immunologic respiratory disease who had been removed from exposure for at least 1 year. Seven had asthma, nine had hemorrhagic rhinitis, four had both, and eight had allergic rhinitis alone. Respiratory symptoms were assessed by physician-administered questionnaires. For each employee, a physical examination, spirometry, and chest roentgenograph were performed. Antibody against HHPA conjugated to human serum albumin (HHP-HSA) was measured using an enzyme-linked immunosorbent assay. Symptoms, signs, and spirometry normalized in all but one employee. There were no chest-roentgenograph findings at follow-up that could be attributed to HHPA. There was a decline in antibody liter for both immunoglobulin E and G against HHP-HSA. In this group of 28 employees, there was only one employee with mild asthma after removal from exposure for at least I year. Although specific antibody was still present in many, the titers were generally lower at follow-up than at presentation.
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Affiliation(s)
- L C Grammer
- Department of Medicine, Northwestern Memorial Hospital, Chicago, IL 60611, USA
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