Asthma prevalence has increased in epidemic proportions with urbanization, but growing up on traditional farms offers protection even today
. The asthma-protective effect of farms appears to be ...associated with rich home dust microbiota
, which could be used to model a health-promoting indoor microbiome. Here we show by modeling differences in house dust microbiota composition between farm and non-farm homes of Finnish birth cohorts
that in children who grow up in non-farm homes, asthma risk decreases as the similarity of their home bacterial microbiota composition to that of farm homes increases. The protective microbiota had a low abundance of Streptococcaceae relative to outdoor-associated bacterial taxa. The protective effect was independent of richness and total bacterial load and was associated with reduced proinflammatory cytokine responses against bacterial cell wall components ex vivo. We were able to reproduce these findings in a study among rural German children
and showed that children living in German non-farm homes with an indoor microbiota more similar to Finnish farm homes have decreased asthma risk. The indoor dust microbiota composition appears to be a definable, reproducible predictor of asthma risk and a potential modifiable target for asthma prevention.
Studies on the longitudinal changes in sensitization to aeroallergens in adult populations are sparse. The aim was to evaluate changes in sensitization to aeroallergens birch, timothy, cat and house ...dust mite (HDM) in an unselected adult population aged from 31 to 46 years. Data were gathered from a cohort of adults (Northern Finland Birth Cohort 1966) who had been skin prick tested (SPT) with birch, timothy, cat and HDM allergens at the age of 31 years and at age 46 (n = 5484 and 5373 respectively). Data from both time points were available for 3409 participants, who made up the cohort of the longitudinal study. The overall prevalence of sensitization to any of the selected allergens was 30.3% (n = 1661) in 31-year-olds and 30.7% (n = 1649) in 46-year-olds. In general, men were more sensitized (P < 0.001) and also had more polysensitization (P < 0.001) compared to women. In longitudinal sub-population incidence of sensitization was 7.1%. Birch was the most prevalent new sensitizer, however, the difference was not statistically significant when compared to cat. We conclude that new sensitization, demonstrated by positive findings in SPT, can still occur in middle age and this should be taken into account when managing allergic manifestations in adults as sensitization can be considered the first step in developing clinical allergy.
Atopic dermatitis is an inflammatory, pruritic skin disease that often occurs in early infancy with a chronic course. However, a specific description of subtypes of atopic dermatitis depending on the ...timing of onset and progression of the disease in childhood is lacking.
To identify different phenotypes of atopic dermatitis using a definition based on symptoms before age 6 years and to determine whether some subtypes are more at risk for developing other allergic diseases.
The Protection Against Allergy Study in Rural Environments (PASTURE) is a European birth cohort where pregnant women were recruited between August 2002 and March 2005 and divided in 2 groups dependent on whether they lived on a farm. Children from this cohort with data on atopic dermatitis from birth to 6 years of age were included.
Atopic dermatitis, defined as an itchy rash on typical locations from birth to 6 years.
The latent class analysis was used to identify subtypes of atopic dermatitis in childhood based on the course of symptoms. Multivariable logistic regressions were used to analyze the association between atopic dermatitis phenotypes and other allergic diseases.
We included 1038 children; of these, 506 were girls. The latent class analysis model with the best fit to PASTURE data separated 4 phenotypes of atopic dermatitis in childhood: 2 early phenotypes with onset before age 2 years (early transient n = 96; 9.2% and early persistent n = 67; 6.5%), the late phenotype with onset at age 2 years or older (n = 50; 4.8%), and the never/infrequent phenotype (n = 825; 79.5%), defined as children with no atopic dermatitis. Children with both parents with history of allergies were 5 times more at risk to develop atopic dermatitis with an early-persistent phenotype compared with children with parents with no history of allergies. Both early phenotypes were strongly associated with food allergy. The risk of developing asthma was significantly increased among the early-persistent phenotype (adjusted odds ratio, 2.87; 95% CI, 1.31-6.31). The late phenotype was only positively associated with allergic rhinitis.
Using latent class analysis, 4 phenotypes of atopic dermatitis were identified depending on the onset and course of the disease. The prevalence of asthma and food allergy by 6 years of age was strongly increased among children with early phenotypes (within age 2 years), especially with persistent symptoms. These findings are important for the development of strategies in allergy prevention.
Background The role of dietary factors in the development of allergies is a topic of debate, especially the potential associations between infant feeding practices and allergic diseases. Previously, ...we reported that increased food diversity introduced during the first year of life reduced the risk of atopic dermatitis. Objective In this study we investigated the association between the introduction of food during the first year of life and the development of asthma, allergic rhinitis, food allergy, or atopic sensitization, taking precautions to address reverse causality. We further analyzed the association between food diversity and gene expression of T-cell markers and of Cε germline transcript, reflecting antibody isotype switching to IgE, measured at 6 years of age. Methods Eight hundred fifty-six children who participated in a birth cohort study, Protection Against Allergy Study in Rural Environments/EFRAIM, were included. Feeding practices were reported by parents in monthly diaries during the first year of life. Data on environmental factors and allergic diseases were collected from questionnaires administered from birth up to 6 years of age. Results An increased diversity of complementary food introduced in the first year of life was inversely associated with asthma with a dose-response effect (adjusted odds ratio with each additional food item introduced, 0.74 95% CI, 0.61-0.89). A similar effect was observed for food allergy and food sensitization. Furthermore, increased food diversity was significantly associated with an increased expression of forkhead box protein 3 and a decreased expression of Cε germline transcript. Conclusion An increased diversity of food within the first year of life might have a protective effect on asthma, food allergy, and food sensitization and is associated with increased expression of a marker for regulatory T cells.
Early-life indoor bacterial exposure is associated with the risk of asthma, but the roles of specific bacterial genera are poorly understood.
We sought to determine whether individual bacterial ...genera in indoor microbiota predict the development of asthma.
Dust samples from living rooms were collected at 2 months of age. The dust microbiota was characterized by using Illumina MiSeq sequencing amplicons of the bacterial 16S ribosomal RNA gene. Children (n = 373) were followed up for ever asthma until the age of 10.5 years.
Richness was inversely associated with asthma after adjustments (P = .03). The phylogenetic microbiota composition in asthmatics patients' homes was characteristically different from that in nonasthmatic subjects' homes (P = .02, weighted UniFrac, adjusted association, permutational multivariate analysis of variance, PERMANOVA-S). The first 2 axis scores of principal coordinate analysis of the weighted UniFrac distance matrix were inversely associated with asthma. Of 658 genera detected in the dust samples, the relative abundances of 41 genera correlated (r > |0.4|) with one of these axes. Lactococcus genus was a risk factor for asthma (adjusted odds ratio, 1.36 95% CI, 1.13-1.63 per interquartile range change). The abundance of 12 bacterial genera (mostly from the Actinomycetales order) was associated with lower asthma risk (P < .10), although not independently of each other. The sum relative abundance of these 12 intercorrelated genera was significantly protective and explained the majority of the association of richness with less asthma.
Our data confirm that phylogenetic differences in the microbiota of infants' homes are associated with subsequent asthma risk and suggest that communities of selected bacteria are more strongly linked to asthma protection than individual bacterial taxa or mere richness.
Living with dogs appears to protect against allergic diseases and airway infections, an effect possibly linked with immunomodulation by microbial exposures associated with dogs. The aim of this study ...was to characterize the influence of dog ownership on house dust microbiota composition. The bacterial and fungal microbiota was characterized with Illumina MiSeq sequencing from floor dust samples collected from homes in a Finnish rural-suburban (LUKAS2, N = 182) birth cohort, and the results were replicated in a German urban (LISA, N = 284) birth cohort. Human associated bacteria variable was created by summing up the relative abundances of five bacterial taxa. Bacterial richness, Shannon index and the relative abundances of seven bacterial genera, mostly within the phyla Proteobacteria and Firmicutes, were significantly higher in the dog than in the non-dog homes, whereas the relative abundance of human associated bacteria was lower. The results were largely replicated in LISA. Fungal microbiota richness and abundance of Leucosporidiella genus were higher in dog homes in LUKAS2 and the latter association replicated in LISA. Our study confirms that dog ownership is reproducibly associated with increased bacterial richness and diversity in house dust and identifies specific dog ownership-associated genera. Dogs appeared to have more limited influence on the fungal than bacterial indoor microbiota.
The occupant as a source of house dust bacteria Täubel, Martin, PhD; Rintala, Helena, PhD; Pitkäranta, Miia, MSc ...
Journal of allergy and clinical immunology,
10/2009, Volume:
124, Issue:
4
Journal Article
Peer reviewed
Open access
Background Markers for microbial groups are commonly measured in house dust samples to assess indoor exposure to microbes in studies on asthma and allergy. However, little is known about the sources ...of different microbes. A better understanding of the nature and origin of microbes present in the immediate environment of human beings is crucial if one wants to elucidate protective as well as adverse effects on human health. Objective To determine the extent to which the bacterial composition of mattress and floor dust reflects the presence of the human body in relation to other environmental sources. Methods House dust and skin surface swab samples of occupants in 4 homes were collected and analyzed for their bacterial content, using a culture-independent methodology. Bacterial sequences analyzed from the different house dusts and skin surface swabs represented random samples of bacteria present in a given sample. Highly similar sequences were grouped to assess biodiversity and to draw conclusions about the sources of bacteria. Results The bacterial flora in the house dust samples was found to be highly diverse and dominated by gram-positive bacteria. To a considerable extent, the presence of different bacterial groups was attributed to human sources. In the individuals' mattress dust samples, 69% to 88% of the bacterial sequences analyzed were associated with human origins. The respective percentages for the individual floor dusts ranged from 45% to 55%. Conclusion Our study indicates that human-derived bacteria account for a large part of the mainly gram-positive bacterial content in house dust.
ObjectivesChronic cough is linked to various long-standing risk factors like asthma, chronic rhinitis and oesophageal reflux disease. On the contrary, acute and subacute cough are usually considered ...to be caused by acute respiratory infections. Little is known about the possible long-standing risk factors for acute and subacute cough. In this study, we have identified the long-standing risk factors for acute, subacute and chronic cough in order to identify the risk factors specifically associated with chronic cough.DesignA comprehensive 80-item questionnaire was sent via email to the participants.SettingA community-based study to all public service employees of two towns in central Finland.ParticipantsThere were 13 980 employees, of them 3697 responded (26.4%). Among the responders, there were 199 subjects with current daily acute cough (duration <3 weeks, prevalence 5.4%), 126 subjects with current daily subacute cough (duration 3–8 weeks, prevalence 3.4%) and 267 subjects with current daily chronic cough (duration >8 weeks, prevalence 7.2%).Primary outcome measuresThe risk factors that associated with each cough subtype. The subjects without any cough formed the reference group.ResultsSeveral risk factors were associated with both short and long cough subtypes namely family history of chronic cough, moisture damage exposure and number of reported somatic symptoms. Furthermore, allergy was associated with acute and subacute cough. Current asthma and chronic rhinitis were associated with subacute and chronic cough. Oesophageal reflux disease and advanced age were associated with chronic cough.ConclusionsThe specific risk factors for chronic cough were oesophageal reflux disease and advanced age. Acute and subacute cough should not be regarded merely as symptoms of acute respiratory infections but possible manifestations of long-standing risk factors. A new risk factor for all cough types was family history of chronic cough.
Studies suggest negative health impacts from early life exposure to per- and polyfluoroalkyl substances (PFASs). However, information on longitudinal exposure to PFASs during childhood is scarce for ...background-exposed individuals. This study sought to fill this gap by investigating children's longitudinal exposure trends through measurement of PFAS serum concentrations and calculation of body burdens (μg, total in body). Blood of 54 Finnish children was sampled 2005–2015 and analyzed for 20 PFASs at 1, 6 and 10.5 years of age. The body burden was calculated by multiplying the serum concentration by the volume of distribution and the bodyweight for each individual. Associations between serum concentrations or body burdens and parameters, such as sex, breastfeeding duration, body mass index as well as indoor dust and air PFAS concentrations, were evaluated. Serum concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) decreased significantly (p < 0.001) with age. In contrast to serum concentrations, body burdens stayed unchanged or even increased significantly (p < 0.05), except for PFOA in female children. Breastfeeding duration was positively correlated (p < 0.001) with serum concentrations of PFHxS, PFOS, PFOA and PFNA at 1 year of age. Some associations were found at 10.5 years with sex and indoor PFAS concentrations. Observations of longitudinal decreasing trends of serum concentrations can be misleading for understanding exposure levels from external media during childhood, as the serum concentration is influenced by parallel temporal changes and growth dilution. Body burdens account for growth dilution and thus better reflect differences in early-life to adolescence exposure than serum concentrations.
•Body burden is better marker for early life exposure than serum concentration.•Serum concentrations of PFAAs decreased significantly with children's age.•PFAA body burdens stayed unchanged or increased significantly with children's age.•Breastfeeding duration was positively correlated with children's serum PFAAs.
PDF
