Differential effects of female sex hormones on cellular recruitment and tracheal reactivity after formaldehyde exposure

Female sex hormones (FSHs) exert profound regulatory effects on the course of lung inflammation due to allergic and non-allergic immune responses. As pollution is one of the pivotal factors to induce lung dysfunction, in this study we investigated the modulatory role of FSHs on lung inflammation after a formaldehyde (FA) exposure. For this purpose, lung and systemic inflammatory responses were evaluated in terms of leukocytes countings in bronchoalveolar lavage (BAL), peripheral blood and bone marrow lavage from 7-day ovariectomized (OVx) and Sham-OVx rats subjected to FA inhalation for 3 consecutive days. The hypothesized link between effects of FSHs on expression of adhesion molecules and mast cells degranulation was also studied. Once exposed to FA, Sham-OVx rats increased the number of total cells recovered in BAL and of leukocytes in peripheral blood, and decreased the counts in bone marrow. By contrast, in OVx rats upon FA exposure there was a reduction of the total cells counts in BAL and of blood leukocytes: lung expressions of ICAM-1 and Mac-1 were depressed, but the number of bone marrow cells did not vary. Estradiol treatment of OVx rats increased the total cells in BAL and decreased the number of blood leukocytes, whereas the number of bone marrow cell remained unaltered. Progesterone treatment, in turn increased the total cells in BAL and blood leukocytes, but decreased the number of bone marrow cells. OVx rats exposed to FA developed tracheal hyperresponsiveness to methacholine (MCh). A similarly altered response was found between the tracheal segments of Sham-OVx rats after FA exposure and that found in tracheae of naive rats. Estradiol treatment prevented FA-induced tracheal hyperresponsiveness to MCh whereas progesterone was ineffective in this regard. In addition, OVx rats upon FA exposure significantly increased both, the ability of mast cell degranulation and serum corticosterone levels. In conclusion, it was found that FSHs act by distinct control mechanisms on FA-induced lung inflammation and tracheal hyperresponsiveness, since at low circulating levels of FSHs (such as those after OVx) there is some resistance to the development of a lung inflammatory response, but the cholinergic tracheal responsiveness is exacerbated. Our data also help to understand the involvement of FSHs on mast cells activity after pollutants exposure and add information regarding the role of FSHs on the mechanisms related to endothelium-leukocyte interactions. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Enhancement of Th1 Lung Immunity Induced by Recombinant Mycobacterium bovis Bacillus Calmette-Guerin Attenuates Airway Allergic Disease

Mycobacterium bovis Bacillus Calmette-Guerin (BCG) has been shown to down-regulate experimental allergic asthma, a finding that reinforced the hygiene hypothesis. We have previously found that recombinant BCG (rBCG) strain that express the genetically detoxified Si subunit of pertussis toxin (rBCG-S1PT) exerts an adjuvant effect that enhances Th1 responses against BCG proteins. Here we investigated the effect of this rBCG-S1PT on the classical ovalbumin-induced mouse model of allergic lung disease. We found that rBCG-S1PT was more effective than wild-type BCG in preventing Th2-mediated allergic immune responses. The inhibition of allergic lung disease was not associated with increased concentration of suppressive cytokines or with an increased number of pulmonary regulatory T cells but was positively correlated with the increase in IFN-gamma-producing T cells and T-bet expression in the lung. In addition, an IL-12-dependent mechanism appeared to be important to the inhibition of lung allergic disease. The inhibition of allergic inflammation was found to be restricted to the lung because when allergen challenge was given by the intraperitoneal route, rBCG-S1PT administration failed to inhibit peritoneal allergic inflammation and type 2 cytokine production. Our work offers a nonclassical interpretation for the hygiene hypothesis indicating that attenuation of lung allergy by rBCG could be due to the enhancement of local lung Th1 immunity induced by rBCG-S1PT. Moreover, it highlights the possible use of rBCG strains as multipurpose immunomodulators by inducing specific immunity against microbial products while protecting against allergic asthma.

Bradykinin inducible receptor is essential to lipopolysaccharide-induced acute lung injury in mice

Lipopolysaccharides from gram-negative bacteria are amongst the most common causative agents of acute lung injury, which is characterized by an inflammatory response, with cellular infiltration and the release of mediators/cytokines. There is evidence that bradykinin plays a role in lung inflammation in asthma but in other types of lung inflammation its role is less clear. In the present study we evaluated the role of the bradykinin B(1) receptor in acute lung injury caused by lipopolysaccharide inhalation and the mechanisms behind bradykinin actions participating in the inflammatory response. We found that in C57BI/6 mice, the bradykinin B(1) receptor expression was up-regulated 24 h after lipopolysaccharide inhalation. At this time, the number of cells and protein concentration were significantly increased in the bronchoalveolar lavage fluid and the mice developed airway hyperreactivity to methacholine. In addition, there was an increased expression of tumor necrosis factor-alpha, interleukin-1 beta and interferon-gamma and chemokines (monocytes chemotactic protein-1 and KC) in the bronchoalveolar lavage fluid and in the lung tissue. We then treated the mice with a bradykinin B, receptor antagonist, R-954 (Ac-Orn-[Oic(2), alpha-MePhe(5), D-beta Nal(7), Ile(8)]desArg(9)-bradykinin), 30 min after lipopolysaccharide administration. We observed that this treatment prevented the airway hyperreactivity as well as the increased cellular infiltration and protein content in the bronchoalveolar lavage fluid. Moreover, R-954 inhibited the expression of cytokines/chemokines. These results implicate bradykinin, acting through B(1) receptor, in the development of acute lung injury caused by lipopolysaccharide inhalation. (C) 2010 Elsevier B.V. All rights reserved.

Connective tissue mast cells are the target of formaldehyde to induce tracheal hyperresponsiveness in rats: Putative role of leukotriene B(4) and nitric oxide

Formaldehyde (FA) exposure induces upper airways irritation and respiratory abnormalities, but its mechanisms are not understood. Since mast cells are widely distributed in the airways, we hypothesized that FA might modify the airways reactivity by mechanism involving their activation. Tracheal rings of rats were incubated with Dulbecco`s modified medium culture containing FA (0.1 ppm) in 96-well plastic microplates in a humid atmosphere. After 30 min, 6 h, and 24-72 h, the rings were suspended in an organ bath and dose-response curve to methacholine (MCh) were determined. incubation with FA caused a transient tracheal hyperresponsiveness to MCh that was independent from tracheal epithelium integrity. Connective tissue mast cell depletion caused by compound 48/80 or mast cell activation by the allergic reaction, before exposure of tracheal rings to FA prevented the increased responsiveness to MCh. LTB(4) concentrations were increased in the culture medium of tracheas incubated with FA for 48 h, whereas the LTB(4)-receptor antagonist MK886 (1 mu M) added before FA exposure rendered the tracheal rings normoreactive to MCh. In addition, FA exposure did not cause hyperresponsiveness in tracheal segments incubated with L-arginine (1 mu M). We suggest that airway connective tissue mast cells constitute the target and may provide the increased LTB(4) generation as well as an elevated consumption of NO leading to tracheal hyperresponsiveness to MCh. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Preventive and curative glycoside kaempferol treatments attenuate the TH2-driven allergic airway disease

Asthma is a chronic respiratory disease characterized by airway inflammation and airway hyperresponsiveness (AHR). One strategy to treat allergic diseases is the development of new drugs. Flavonoids are compounds derived from plants and are known to have antiallergic, anti-inflammatory, and antioxidant properties. To investigate whether the flavonoid kaempferol glycoside 3-O-[beta-D-glycopiranosil-(1 -> 6)-alpha-L-ramnopiranosil]-7-O-alpha-L-ramnopiranosil-kaempferol (GRRK) would be capable of modulating allergic airway disease (AAD) either as a preventive (GRRK P) or curative (GRRK C) treatment in an experimental model of asthma. At weekly intervals, BALB/c mice were subcutaneously (sc) sensitized twice with ovalbumin (OVA)/alum and challenged twice with OVA administered intranasally. To evaluate any preventive effects GRRK was administered 1 h (hour) before each OVA-sensitization and challenge, while to analyze the curative effects mice were first sensitized with OVA, followed by GRRK given at day 18 through 21. The onset: of AAD was evaluated 24 h after the last OVA challenge. Both treatments resulted in a dose-dependent reduction in total leukocyte and eosinophil counts in the bronchoalveolar lavage fluid (BAL). GRRK also decreased CD4(+), B220(+), MHC class II and CD40 molecule expressions in BAL cells. Histology and lung mechanic showed that GRRK suppressed mucus production and ameliorated the AHR induced by OVA challenge. Furthermore, GRRK impaired Th2 cytokine production (IL-5 and IL-13) and did not induce a Th1 pattern of inflammation. These findings demonstrate that GRRK treatment before or after established allergic lung disease down-regulates key asthmatic features. Therefore. GRRK has a potential clinical use for the treatment of allergic asthma. (C) 2009 Elsevier B.V. All rights reserved.

Notch signaling controls the balance of ciliated and secretory cell fates in developing airways

Although there is accumulated evidence of a role for Notch in the developing lung, it is still unclear how disruption of Notch signaling affects lung progenitor cell fate and differentiation events in the airway epithelium. To address this issue, we inactivated Notch signaling conditionally in the endoderm using a Shh-Cre deleter mouse line and mice carrying floxed alleles of the Pofut1 gene, which encodes an O-fucosyltransferase essential for Notch-ligand binding. We also took the same conditional approach to inactivate expression of Rbpjk, which encodes the transcriptional effector of canonical Notch signaling. Strikingly, these mutants showed an almost identical lung phenotype characterized by an absence of secretory Clara cells without evidence of cell death, and showed airways populated essentially by ciliated cells, with an increase in neuroendocrine cells. This phenotype could be further replicated in cultured wild-type lungs by disrupting Notch signaling with a gamma-secretase inhibitor. Our data suggest that Notch acts when commitment to a ciliated or non-ciliated cell fate occurs in proximal progenitors, silencing the ciliated program in the cells that will continue to expand and differentiate into secretory cells. This mechanism may be crucial to define the balance of differentiated cell profiles in different generations of the developing airways. It might also be relevant to mediate the metaplastic changes in the respiratory epithelium that occur in pathological conditions, such as asthma and chronic obstructive pulmonary disease.

Association between particulate matter from biomass burning and respiratory diseases in the southern region of the Brazilian Amazon

Objective. To investigate the short-term effects of exposure to particulate matter from biomass burning in the Amazon on the daily demand for outpatient care due to respiratory diseases in children and the elderly. Methods. Epidemiologic study with ecologic time series design. Daily consultation records were obtained from the 14 primary health care clinics in the municipality of Alta Floresta, state of Mato Grosso, in the southern region of the Brazilian Amazon, between January 2004 and December 2005. Information on the daily levels of fine particulate matter was made available by the Brazilian National Institute for Spatial Research. To control for confounding factors ( situations in which a non-causal association between exposure and disease is observed due to a third variable), variables related to time trends, seasonality, temperature, relative humidity, rainfall, and calendar effects ( such as occurrence of holidays and weekends) were included in the model. Poisson regression with generalized additive models was used. Results. A 10 mu g/m(3) increase in the level of exposure to particulate matter was associated with increases of 2.9% and 2.6% in outpatient consultations due to respiratory diseases in children on the 6th and 7th days following exposure. Significant associations were not observed for elderly individuals. Conclusions. The results suggest that the levels of particulate matter from biomass burning in the Amazon are associated with adverse effects on the respiratory health of children.

Percolation in a network with long-range connections: Implications for cytoskeletal structure and function

Cell shape, signaling, and integrity depend on cytoskeletal organization. In this study we describe the cytoskeleton as a simple network of filamentary proteins (links) anchored by complex protein structures (nodes). The structure of this network is regulated by a distance-dependent probability of link formation as P = p/d(s), where p regulates the network density and s controls how fast the probability for link formation decays with node distance (d). It was previously shown that the regulation of the link lengths is crucial for the mechanical behavior of the cells. Here we examined the ability of the two-dimensional network to percolate (i.e. to have end-to-end connectivity), and found that the percolation threshold depends strongly on s. The system undergoes a transition around s = 2. The percolation threshold of networks with s < 2 decreases with increasing system size L, while the percolation threshold for networks with s > 2 converges to a finite value. We speculate that s < 2 may represent a condition in which cells can accommodate deformation while still preserving their mechanical integrity. Additionally, we measured the length distribution of F-actin filaments from publicly available images of a variety of cell types. In agreement with model predictions, cells originating from more deformable tissues show longer F-actin cytoskeletal filaments. (C) 2008 Elsevier B.V. All rights reserved.

Livskvalitet i familjer med barn och ungdomar med astma : en systematisk litteraturstudie

Syftet med litteraturstudien var att beskriva vilken livskvalitet barn och ungdomar med astma och deras f��r��ldrar hade. Till resultatet anv��ndes tretton vetenskapliga artiklar publicerade tidigast ��r 2000. Databaserna Elin, Blackwell Synergy och Ebsco Host anv��ndes vid artikels��kningen och en manuell s��kning gjordes via www.asthma.se. S��korden asthma, child, parents, quality of life, experience och coping anv��ndes i olika kombinationer. Artikelurvalet gjordes f��r att passa litteraturstudiens syfte och fr��gest��llningar och det vetenskapliga v��rdet i artiklarna skattades med hj��lp av modifierade granskningsmallar. Resultatet visade att barn och ungdomar med astma hade relativt h��gt skattad livskvalitet och hade l��rt sig att hitta strategier f��r att hantera sin sjukdom och d��rmed kunna leva ett s�� normalt liv som m��jligt. M��nga av barnen och ungdomar testade gr��nser f��r hur mycket kroppen t��lde genom p��frestande fysiska aktiviteter. F��r de ungdomarna som hade l��gt skattad livskvalitet kunde orsakerna h��rledas till d��lig kontrollerade astmasymtom eller d�� omgivningen p��verkade barnet negativt. Flickor hade l��gre livskvalitet ��n pojkar i studierna. F��r��ldrarna till barn och ungdomar med astma var generellt mer p��verkade av barnets sjukdom ��n barnen sj��lva. De fanns vissa skillnader mellan f��r��ldrarna, m��drarna var mer bekymrade och oroade medan f��derna hade ett mer avslappnat f��rh��llande till barnet och sjukdomen.

Implementation of Video Monitoring In Aluminium Industry

The aim was to evaluate results and experiences from development of new technology, a training program and implementation of strategies for the use of a video exposure monitoring method, PIMEX. Starting point of this study is an increased incidence of asthma among workers in the aluminium industry. Exposure peaks of fumes are supposed to play an important role. PIMEX makes it possible to link used work practice, use of control technology, and so forth to peaks. Nine companies participated in the project, which was divided into three parts, development of PIMEX technology, production of training material, and training in use of equipment and related strategies. The use of the video exposure monitoring method PIMEX offers prerequisites supporting workers participation in safety activities. The experiences from the project reveal the importance of good timing of primary training, technology development, technical support, and follow up training. In spite of a delay of delivery of the new technology, representatives from the participating companies declared that the experiences showed that PIMEX gave an important contribution for effective control of hazards in the companies. Eight out of nine smelters used the PIMEX method as a part of a strategy for control of workers exposure to fumes in potrooms. Possibilities to conduct effective control measures were identified. This article describes experiences from implementation of a, for this branch, new method supporting workers participation for workplace improvements.

Informations- och kommunikationsteknologi som st��d f��r patienter med astma och kronisk obstruktiv lungsjukdom avseende egenv��rd. En litteraturstudie.

Bakgrund: Astma och KOL ��r tv�� vanlig kroniska sjukdomar som ��r kopplade till stort sjukdomslidande och l��gre livskvalit��. M��nga personer som idag lever med sjukdomarna lever isolerat fr��n andra. Idag har vi en st��ndig utveckling av sociala n��tverk som ��ppnar en ny m��jlighet f��r egenv��rd. Egenv��rd kan g��ra att patienter f��r en b��ttre vardag samt att det l��ttare kan f�� ett socialt umg��nge. Syfte: Syftet ��r sammanst��lla befintlig litteratur och d��r unders��ka hur informations- och kommunikationsteknologi underl��ttar egenv��rden f��r patienter med astma och KOL. Metod: Litteraturstudie d��r artiklarna s��ktes i databaser f��r omv��rdnadsvetenskap s�� som Web Of Science, pubmed och Cinahl. Litteraturstudien baseras p�� 16 vetenskapliga artiklar som b��de ��r kvalitativa och kvantitativa. Artiklarna som valdes ��r inte ��ldre ��n 10 ��r gamla, skrivna p�� engelska och publicerade i en vetenskaplig tidning. Resultat: Resultatet som artiklarna p��visade ��r grundade p�� IKT i form av datorer, mobiltelefoner, surfplattor och web-baserad program. Artiklarna visar att egenv��rden kan f��rb��ttras genom ��kad livskvalit��, b��ttre kommunikation och b��ttre sjukdomsinsikt n��r man anv��nder IKT. Slutsats: IKT ��r en viktig roll i v��ran h��lso- och sjukv��rd idag. Det finns dock liten forskning p�� hur egenv��rden kring astma och KOL p��verkas av IKT. Den forskning som finns pekar ��t ��r att den f��rb��ttrar f��r patienter. Det beh��vs ��ven mer forskning kring IKT som en resurs f��r egenv��rd kring ett omv��rdnadsperspektiv.

Fungos anem��filos em Porto Alegre, RS.

O conhecimento dos fungos anem��filos em determinada cidade ou regi��o �� importante para o diagn��stico etiol��gico e o tratamento espec��fico das manifesta����es al��rgicas respirat��rias. V��rias t��cnicas quantitativas e qualitativas s��o preconizadas para coleta e identifica����o desses fungos na depend��ncia do local estudado. Nesta pesquisa, sobre esporos de fungos do ar, foi utilizado o equipamento Rotorod Sampler��, que retira a amostra do ar atrav��s de um bast��o de pl��stico preso a um motor el��trico que o faz girar rapidamente, sendo as part��culas suspensas no ar recolhidas pelo bast��o. As amostras foram coletadas uma vez por semana, durante 24 horas, correspondendo a um ciclo de coleta. Foram realizadas 52 coletas entre abril de 2000 e mar��o de 2001. Os resultados mostraram preval��ncia de ascosporos (50,49%), Cladosporium (17,86%), Aspergillus/Penicillium (15,03%), basidiosporos (3,84%), rusts (3,82%), Helminthosporium (2,49%), Botrytis (1,22%), Alternaria (1,19%), smuts (0,90%), Curvularia (0,87%), Nigrospora (0,61%) e Fusarium (0,08%). N��o foi poss��vel identificar 1,59% dos esporos de fungos coletados no per��odo. O maior n��mero de esporos foi observado nos meses de ver��o e o menor, durante o outono. Utilizando provas in vivo e in vitro, avaliou-se a hipersensibilidade a fungos entre 39 pacientes at��picos sofrendo de rinite e ou asma br��nquica. Os testes cut��neos identificaram sensibiliza����o em 17,94% dos pacientes, enquanto as provas sorol��gicas caracterizaram presen��a de IgE espec��fica em 12,82% dos casos avaliados. A detec����o de significativo n��mero de esporos de fungos no ar de Porto Alegre, com muitas esp��cies comprovadamente alerg��nicas, e os ��ndices de sensibiliza����o observados em indiv��duos at��picos confirmam a import��ncia do estudo dos fungos anem��filos nessa cidade, com vistas a aprimorar o diagn��stico e o manejo de pacientes com manifesta����es al��rgicas respirat��rias.

Estudo da resposta inflamat��ria em lactentes com sibil��ncia : an��lise de IL-10 e celularidade no aspirado nasofar��ngeo

Epis��dios de sibil��ncia secund��rios a infec����es respirat��rias virais s��o comuns nos primeiros anos de vida. Contudo, sua patog��nese e rela����o com o posterior surgimento de asma permanecem ainda pouco esclarecidos. Com o objetivo de analisar a resposta celular e da IL-10 em lactentes com sibil��ncia, foram analisadas amostras de aspirado nasofar��ngeo de 71 lactentes. Os pacientes foram classificados em tr��s grupos: primeiro epis��dio de sibil��ncia (n=36), sibil��ncia recorrente (n=18) e infec����o de vias a��reas superiores (n=17). O exame citol��gico da secre����o nasofar��ngea demonstrou uma predomin��ncia de neutr��filos em todos os grupos. N��o foi evidenciada a presen��a de eosin��filos na secre����o nasofar��ngea de nenhum paciente, exceto em um caso do grupo de sibil��ncia recorrente, cujo percentual dessas c��lulas foi de 1%. Foram encontrados n��veis de IL-10 significativamente aumentados no aspirado nasofar��ngeo do grupo com primeiro epis��dio de sibil��ncia, quando comparados ao grupo de infec����o de vias a��reas superiores (p=0,017). N��o foi encontrada correla����o significativa entre os n��veis de IL-10 em secre����o nasofar��ngea e gravidade do epis��dio de sibil��ncia. Conclui-se que os neutr��filos s��o as c��lulas que predominam na resposta inflamat��ria em lactentes com sibil��ncia secund��ria �� infec����o respirat��ria viral e que a IL-10 pode ser uma citocina com participa����o importante na predisposi����o �� doen��a obstrutiva br��nquica do lactente.

Preval��ncia da asma br��nquica e seus fatores de risco na popula����o adulta de Pelotas, Rio Grande do Sul, 2001

A asma br��nquica �� uma doen��a cr��nica inflamat��ria das vias a��reas que vem despertando preocupa����o crescente, em fun����o do aumento na sua incid��ncia e mortalidade observados nos ��ltimos anos. Com o objetivo principal de avaliar a sua preval��ncia e seus fatores de risco, conduziu-se um estudo epidemiol��gico de base populacional, delineamento transversal, em uma amostra representativa de adultos de 20 a 69 anos de idade, residentes na zona urbana de Pelotas, RS. Foram entrevistadas 1.968 pessoas. Desse total, 446 pessoas foram aleatoriamente selecionadas para realizarem espirometria e, quando esta mostrava-se normal, teste de broncoprovoca����o com metacolina. Ainda foram realizados testes para atopia. Houve 9,6% de recusas para as entrevistas e 20,2% de perdas para os exames complementares. Mais de metade da amostra era constitu��da por pessoas com idade inferior a 50 anos, sendo 57% do sexo feminino e a maioria da ra��a branca. A renda familiar, na maioria da amostra, era de at�� tr��s sal��rios m��nimos. A preval��ncia de ���sintomas atuais de asma��� foi de 6,0%. Observou-se varia����o na preval��ncia de asma com a utiliza����o de diferentes crit��rios diagn��sticos: asma cumulativa: 14,3%; diagn��stico m��dico de asma: 12,9%; asma atual: 4,7%; e sintomas atuais ou reversibilidade (obstru����o com resposta ao broncodilatador ou broncoprovoca����o positiva): 9,3%. Gravidade da asma foi avaliada conforme hist��ria de hospitaliza����o por asma, mais de seis visitas ao pronto-socorro por ano e interna����o em Unidade de Tratamento Intensivo. Cerca de 30% dos asm��ticos preencheram algum crit��rio de gravidade para asma. Apenas 20% dos pacientes com asma haviam consultado no ��ltimo ano pela doen��a e somente 30% utilizava alguma medica����o antiasm��tica. Em rela����o aos fatores de risco, na an��lise bruta, as vari��veis associadas �� preval��ncia de ���sintomas atuais de asma��� foram: sexo feminino, faixa et��ria dos 60 aos 69 anos, cor da pele n��o branca, baixas escolaridade e renda familiar, hist��ria familiar de asma e atopia, hist��ria pessoal de atopia, tabagismo, ��ndice de massa corporal baixo e a presen��a de dist��rbios psiqui��tricos menores. Na an��lise multivariada, construiu-se um modelo te��rico-hierarquizado cujas vari��veis de um determinado n��vel foram controladas pelas vari��veis de n��veis precedentes e do mesmo n��vel. Permaneceram relacionados �� presen��a de ���sintomas atuais de asma��� os seguintes fatores de risco, em ordem decrescente de raz��o de preval��ncia: hist��ria paterna e materna de asma (RP=5,4), presen��a de dist��rbios psiqui��tricos menores (RP=2,8); idade de 60 a 69 anos (RP=2,1); renda familiar inferior a 1,01 SM (RP=2,1); hist��ria pessoal de atopia (RP=1,9); e sexo feminino (RP=1,4). Os resultados do presente estudo salientam a varia����o na preval��ncia de asma com a utiliza����o de diferentes crit��rios diagn��sticos, e confirmam a import��ncia dos fatores gen��ticos, sociais e relacionados ao estilo de vida na ocorr��ncia da doen��a.

Preval��ncia de v��rus respirat��rio em pacientes atendidos por asma aguda na sala de emerg��ncia

Introdu����o: As infec����es virais do trato respirat��rio (IVTR) t��m sido freq��entemente identificadas em associa����o com asma aguda (AA) em crian��as, por��m poucos estudos t��m mostrado resultados similares em adultos com asma. Objetivos: Avaliar a preval��ncia de infec����o viral na asma aguda em pacientes atendidos no setor de adultos do departamento de emerg��ncia (DE), comparando as caracter��sticas entre os grupos com amostras positivas e negativas para os v��rus respirat��rios. Material e M��todos: Conduzimos um estudo transversal de pacientes que se apresentaram com AA no setor de adultos do DE (idade igual ou maior que 12 anos) do Hospital de Cl��nicas de Porto Alegre. Um aspirado nasofar��ngeo foi obtido para detec����o de ant��geno com a t��cnica de colora����o de imunofluoresc��ncia indireta (v��rus sincicial respirat��rio, adenov��rus, influenza e parainfluenza tipo 1, 2, 3 e 4). Foram coletados dados referentes a caracter��sticas demogr��ficas, medica����es regulares, hist��ria m��dica pregressa, crise que levou �� atual visita ao DE e desfechos da crise. Resultados: No per��odo de mar��o de 2004 a novembro de 2005, 111 pacientes foram examinados para IVTR. Foram identificados v��rus respirat��rios em 15 pacientes (8 com Adenov��rus, 1 com RSV, 2 com Influenza A, e 4 com Parainfluenza tipo 1). Utilizando a an��lise de regress��o log��stica, as vari��veis com (p < 0,10), ��ndice de massa corporal (IMC) e febre no domicilio, foram significativamente associados �� identifica����o de v��rus respirat��rio. Sessenta e seis por cento dos pacientes com IVTR apresentaram febre no domic��lio, enquanto que somente 27% dos pacientes sem infec����o viral apresentaram febre a domic��lio, (p = 0,006). N��o houve outra diferen��a significativa nas caracter��sticas cl��nicas, tempo de perman��ncia e desfechos. Conclus��o: Este estudo mostra uma preval��ncia de 13,5% de IVTR na AA em pacientes com idade igual ou maior que 12 anos atendidos na sala de emerg��ncia, confirmando a infec����o viral como importante desencadeante nesta faixa et��ria. Dentre as caracter��sticas cl��nicas estudadas, febre no domic��lio e IMC elevado, apresentam maior chance de identifica����o viral positiva.