Outcomes of childhood asthma to the age of 50 years.

BACKGROUND: In 1964, The Melbourne Asthma Study was established to describe the spectrum and natural history of childhood asthma. OBJECTIVE: To describe the clinical and lung function outcome of childhood asthma to the age of 50 years. METHOD: Subjects were invited to complete an interviewer-administered questionnaire, skin prick testing, and measurement of lung function from the age of 7 years to the age of 50 years at 7-year intervals. RESULTS: Of 458 survivors (from the original 484 subjects at recruitment), 346 subjects (76%) participated, of whom, 197 completed lung function measurement. Asthma remission at the age of 50 years was 64% in those with wheezy bronchitis, 47% for those with persistent asthma, and 15% for those with severe asthma in childhood. Multivariable analysis identified severe asthma in childhood (odds ratio [OR] 11.9 [95% CI, 3.4-41.8]), female sex (OR 2.0 [95% CI, 1.1-3.6]), and childhood hay fever (OR 2.0 [95% CI, 1.0-4.0]) as risk factors for "current asthma" at age 50 years. There was no evidence of a difference in the rate of decline in FEV1 (mL/y, 95% CI) between the severe asthma group (15 mL/y [95% CI, 9-22 mL/y]) and all the other recruitment groups: control (16 mL/y [95% CI, 12-20 mL/y]), mild wheezy bronchitis (14 mL/y [95% CI, 8-19 mL/y]), wheezy bronchitis (16 mL/y [95% CI, 11-20 mL/y]), and persistent asthma (19 mL/y [95% CI, 13-24 mL/y]). CONCLUSION: The clinical and lung function outcome in adult life is strongly determined by asthma severity in childhood. The reduced lung function seen in adults is established in childhood and does not appear to decline more rapidly in adult years despite continuing symptoms.

The association between childhood asthma and adult chronic obstructive pulmonary disease.

INTRODUCTION: There is epidemiological evidence to suggest that events in childhood influence lung growth and constitute a significant risk for adult COPD. The aim of the study is to evaluate for an association between childhood asthma and adult COPD. METHODS: This longitudinal, prospective study of 6-7-year-old children with asthma has been regularly reviewed every 7 years to the current analysis at 50 years of age. Participants completed respiratory questionnaires and lung function spirometry with postbronchodilator response. At the age of 50, subjects were classified to the following subgroups: non-asthmatics, asthma remission, current asthma and COPD which was defined by FEV1 to FVC ratio postbronchodilator of less than 0.7. RESULTS: Of the remaining survivors, 346 participated in the current study (participation rate of 76%) of whom 197 completed both questionnaire and lung function testing. As compared with children without symptoms of wheeze to the age of 7, (non-asthmatics) children with severe asthma had an adjusted 32 times higher risk for developing COPD (95% CI 3.4 to 269). In this cohort, 43% of the COPD group had never smoked. There was no evidence of a difference in the rate of decline in FEV1 (mL/year, 95th CI) between the COPD group (17, 10 to 23) and the other groups: non-asthmatics (16, 12 to 21), asthma remission (20, 16 to 24) and current asthma (19, 13 to 25). CONCLUSIONS: Children with severe asthma are at increased risk of developing COPD.

Trends in eczema, rhinitis, and rye grass sensitization in a longitudinal asthma cohort.

BACKGROUND: Atopic conditions are prevalent in the Western world, with limited long-term data on atopic trends in patients with asthma. OBJECTIVE: To describe the trends in eczema, rhinitis, and allergic sensitization in a longitudinal childhood asthma cohort. METHODS: Four hundred eighty-four patients were recruited at 7 years of age and followed regularly to 50 years of age. Subjects completed an interviewer-administered questionnaire to define current eczema and rhinitis. Skin prick testing to rye grass also was performed. RESULTS: The participation rate over the past 4 decades has been maintained at 72% to 91%. There was a decrease in the prevalence of eczema in the past 12 months in groups with viral-associated wheeze (21% to 8%, P = .002), asthma (47% to 18%, P < .001), and severe asthma (69% to 28%, P < .001) from 14 to 21 years of age. Conversely, there was an increase in the prevalence of rhinitis in the previous 12 months in groups without asthma (1% to 6%, P = .04; 1% to 20%, P = .008), with viral-associated wheeze (16% to 28%, P = .006; 16% to 49%, P < .001), and with asthma (45% to 56%, P = .2; 45% to 73%, P = .014) from recruitment to 10 and 14 years of age, respectively. There were 2 peaks in prevalence in the sensitization to rye grass in this cohort from 7 to 10 years of age and from 14 to 21 years of age in all groups. CONCLUSION: The adolescence phase appears to be an important period in the body's response to allergens whereby eczema decreases in prevalence, whereas rhinitis and rye grass sensitization increase in prevalence.

Pathotyping of Australian isolates of Marek's disease virus and association of pathogenicity with meq gene polymorphism.

We report the pathotyping of six Australian isolates of Marek's disease virus-1 (MDV1) isolated between 1992 and 2004 and association of virulence with meq gene polymorphism. Unvaccinated and herpesvirus of turkeys (HVT)-vaccinated specific pathogen free chickens were challenged at day 5 with 500 plaque forming units of Marek's disease virus. The isolates induced gross Marek's disease lesions in 53 to 94% of unvaccinated chickens, and HVT induced a protective index ranging from 38 to 100% by 56 days post challenge. This experiment provides evidence that current Australian isolates of MDV1 vary significantly in pathogenicity. However, there was no clear evidence that the most virulent recent isolates were more pathogenic than isolates from the 1980s or that any of the isolates belong to the highest pathotype category of very virulent plus. Evidence is presented that virulence can be predicted by measurements taken as early as 13 days post challenge. The meq gene sequences of five of the isolates used in the experiment were determined. When compared with the very virulent US isolate Md5, there was a 177 base-pair insertion and distinct point mutations in each of the five isolates. There were no individual mutations in the meq sequences that correlated with levels of virulence. However, amino acid alignment of the five Australian and 14 international isolates revealed that the number of repeat sequences of four prolines (PPPP repeats) in the meq gene (overall range 2 to 8) was strongly associated with virulence across all isolates, with the most pathogenic isolates having the fewest number of repeats. The results suggest that the presence of the 177 base-pair insertion alone is not an indicator of attenuation. Rather, the number of PPPP repeats, independent of the presence of the insertion, is a better indicator of pathogenicity.

ACE2 Expression in Organotypic Human Airway Epithelial Cultures and Airway Biopsies.

Coronavirus disease 2019 (COVID-19) caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an acute respiratory disease with systemic complications. Therapeutic strategies for COVID-19, including repurposing (partially) developed drugs are urgently needed, regardless of the increasingly successful vaccination outcomes. We characterized two-dimensional (2D) and three-dimensional models (3D) to establish a physiologically relevant airway epithelial model with potential for investigating SARS-CoV-2 therapeutics. Human airway basal epithelial cells maintained in submerged 2D culture were used at low passage to retain the capacity to differentiate into ciliated, club, and goblet cells in both air-liquid interface culture (ALI) and airway organoid cultures, which were then analyzed for cell phenotype makers. Airway biopsies from non-asthmatic and asthmatic donors enabled comparative evaluation of the level and distribution of immunoreactive angiotensin-converting enzyme 2 (ACE2). ACE2 and transmembrane serine proteinase 2 (TMPRSS2) mRNA were expressed in ALI and airway organoids at levels similar to those of native (i.e., non-cultured) human bronchial epithelial cells, whereas furin expression was more faithfully represented in ALI. ACE2 was mainly localized to ciliated and basal epithelial cells in human airway biopsies, ALI, and airway organoids. Cystic fibrosis appeared to have no influence on ACE2 gene expression. Neither asthma nor smoking status had consistent marked influence on the expression or distribution of ACE2 in airway biopsies. SARS-CoV-2 infection of ALI cultures did not increase the levels of selected cytokines. Organotypic, and particularly ALI airway cultures are useful and practical tools for investigation of SARS-CoV-2 infection and evaluating the clinical potential of therapeutics for COVID-19.

Phagocyte extracellular traps in children with neutrophilic airway inflammation.

Childhood lung infection is often associated with prominent neutrophilic airway inflammation and excess production of proteases such as neutrophil elastase (NE). The mechanisms responsible for this inflammation are not well understood. One potentially relevant pathway is the production of extracellular traps by neutrophils (NETs) and macrophages (METs). The aim of this study was to measure NET and MET expression in children and the effect of deoxyribonculease (DNase) 1 and α1-antitrypsin (AAT) on this process. We studied 76 children (median age of 4.0 years) with cystic fibrosis or chronic cough who underwent investigational bronchoscopy. NETs, METs and neutrophil elastase activity in bronchoalveolar lavage (BAL) samples were measured using confocal microscopy and functional assays. The effects of DNase 1 and AAT on NET/MET expression and neutrophil elastase activity were examined in vitro. Both subject groups had airway neutrophilia with prominent BAL production of NETs with neutrophil elastase co-expression; the mean %±standard error of the mean of neutrophils expressing NETs in the cystic fibrosis group was 23.3±2.8% and in the non-cystic fibrosis group was 28.4±3.9%. NET expression was higher in subjects who had detectable neutrophil elastase activity (p≤0.0074). The percentage of macrophages expressing METs in the cystic fibrosis group was 10.7±1.2% and in the non-cystic fibrosis group was 13.2±1.9%. DNase 1 decreased NET/MET expression (p<0.0001), but increased neutrophil elastase activity (p≤0.0137). The combination of AAT and DNase 1 reduced neutrophil elastase activity (p≤0.0049). We observed prominent extracellular trap formation in symptomatic children with and without cystic fibrosis. This innate inflammatory response was down-regulated by a combination of currently available therapeutics.

Optimization of methods for the isolation of Marek's disease viruses in primary chicken cell cultures.

A real-time PCR was used to measure increases in viral DNA in Marek's disease virus (MDV)-infected primary chicken cell cultures in order to optimize methods for viral isolation. Serotype-1 and -3 vaccine and serotype-1 challenge strains exhibited similar growth characteristics, with increases in viral DNA being proportional to inoculum size. Studies of viral growth revealed a linear relationship between increase in MDV copy number and infectious titre, although the rate of increase for copy number was greater. Using real-time PCR, viral DNA yields of the virulent Woodlands strain in infected chicken kidney cultures were shown to be slightly, but not significantly, higher than in chicken embryo kidney cultures and significantly higher than in chicken embryo fibroblast cultures. Viral DNA levels in freshly trypsinised cells suspended in growth medium and infected with the Woodlands strain were higher than levels obtained following the inoculation of monolayer cultures. For cells infected in suspension, no significant enhancement of yield was observed following a medium change after 2-3 days. Peak yields were obtained at days 6-8 after inoculation of all cultures. Findings obtained from the optimization of viral DNA levels were applied to a program for the isolation of Australian strains of serotype-1 viruses from problem flocks over 3 years. Significant improvements were obtained in the isolation rate of strains capable of growing to high titre (>10(4) plaque-forming units/mL) for use in challenge studies.

Association of Antibiotics, Airway Microbiome, and Inflammation in Infants with Cystic Fibrosis.

RATIONALE: The underlying defect in the cystic fibrosis (CF) airway leads to defective mucociliary clearance and impaired bacterial killing, resulting in endobronchial infection and inflammation that contributes to progressive lung disease. Little is known about the respiratory microbiota in the early CF airway and its relationship to inflammation. OBJECTIVES: To examine the bacterial microbiota and inflammatory profiles in bronchoalveolar lavage fluid and oropharyngeal secretions in infants with CF. METHODS: Infants with CF from U.S. and Australian centers were enrolled in a prospective, observational study examining the bacterial microbiota and inflammatory profiles of the respiratory tract. Bacterial diversity and density (load) were measured. Lavage samples were analyzed for inflammatory markers (interleukin 8, unbound neutrophil elastase, and absolute neutrophil count) in the epithelial lining fluid. RESULTS: Thirty-two infants (mean age, 4.7 months) underwent bronchoalveolar lavage and oropharyngeal sampling. Shannon diversity strongly correlated between upper and lower airway samples from a given subject, although community compositions differed. Microbial diversity was lower in younger subjects and in those receiving daily antistaphylococcal antibiotic prophylaxis. In lavage samples, reduced diversity correlated with lower interleukin 8 concentration and absolute neutrophil count. CONCLUSIONS: In infants with CF, reduced bacterial diversity in the upper and lower airways was strongly associated with the use of prophylactic antibiotics and younger age at the time of sampling; less diversity in the lower airway correlated with lower inflammation on bronchoalveolar lavage. Our findings suggest modification of the respiratory microbiome in infants with CF may influence airway inflammation.

Molecular evaluation of responses to vaccination and challenge by Marek's disease viruses.

A real-time quantitative polymerase chain reaction was utilized to study the in vivo replication of Marek's disease vaccine viruses and of virulent oncogenic strains. In the first of four experiments, the growth of the herpes virus of turkeys (HVT) vaccine was detectable in various organs of infected chicken embryos, with the highest viral loads being present in the spleen. No evidence was obtained for replication of serotype-1 Marek's disease viruses in embryos. In the second experiment, viral loads were measured in several organs of chickens after administration of the Rispens and HVT vaccines immediately after hatching. Lowest levels were noted for the Rispens strain after 1 to 8 weeks. By contrast, HVT vaccine grew well in all tested organs, with the highest loads being present in the spleen. Highest loads were observed in unvaccinated birds after challenge with the highly virulent strain MPF57 at day 8, especially in lymphoid organs. A positive relationship was observed between viral load and clinical signs, including tumour formation. In a third study, viral loads were measured in the organs of chickens administered the Rispens vaccine on the day of hatch and challenged at day 8 with MPF57. High levels of clinical protection were afforded against MPF57 by the Rispens vaccine but, in confirmation of earlier findings, sterilizing immunity was not induced. In a fourth study, two experiments were conducted--in which viral loads were measured after challenge of chickens vaccinated with HVT in ovo or at day 1 after hatching. Similar protection was achieved in birds vaccinated in ovo on embryonic days 11 and 17, although protection was slightly, but not significantly, lower than for birds vaccinated at day 1.