Growing up on a farm is associated with an asthma-protective effect, but the mechanisms underlying this effect are largely unknown. In the Protection against Allergy: Study in Rural Environments (PASTURE) birth cohort, we modeled maturation using 16S rRNA sequence data of the human gut microbiome in infants from 2 to 12 months of age. The estimated microbiome age (EMA) in 12-month-old infants was associated with previous farm exposure (β = 0.27 (0.12–0.43), P = 0.001, n = 618) and reduced risk of asthma at school age (odds ratio (OR) = 0.72 (0.56–0.93), P = 0.011). EMA mediated the protective farm effect by 19%. In a nested case–control sample (n = 138), we found inverse associations of asthma with the measured level of fecal butyrate (OR = 0.28 (0.09–0.91), P = 0.034), bacterial taxa that predict butyrate production (OR = 0.38 (0.17–0.84), P = 0.017) and the relative abundance of the gene encoding butyryl–coenzyme A (CoA):acetate–CoA-transferase, a major enzyme in butyrate metabolism (OR = 0.43 (0.19–0.97), P = 0.042). The gut microbiome may contribute to asthma protection through metabolites, supporting the concept of a gut–lung axis in humans.
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Taxonomy was assigned using the Greengenes database (http://greengenes.lbl.gov) for 16S rRNA sequences and the UNITE dynamic database (https://unite.ut.ee/) for ITS sequences. All 16S rRNA and ITS sequences are deposited in the Supplementary Information without metadata. PASTURE is an ongoing birth cohort with fieldwork still being executed. As long as the study is not anonymized, European data protection legislation prohibits sharing of individual data, even when pseudonymized. Upon request, the authors will share aggregate data that do not allow identification of individuals.
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This paper is dedicated to Jean-Charles Dalphin, one of the founders of the PASTURE study, who passed away shortly after the submission of this manuscript. We are very grateful for his constant support of this successful collaboration. We thank B. Stecher and A.-L. Boulesteix for valuable input in discussions about biological and statistical issues, respectively. We are grateful to G. Pagani for technical support with graphs. The PASTURE study was supported by the European Commission (research grants QLK4-CT-2001-00250, FOOD-CT-2006-31708 and KBBE-2007-2-2-06) and the European Research Council (grant 250268). The current analyses were supported by the German Federal Ministry of Education and Research (BMBF; project German Center for Lung Research (DZL)). P.L. and F.M.F. receive funding from the Scottish Government’s Rural and Environment Sciences and Analytical Services Division (RESAS).
D.A.M. is a co-founder of Evolve Biosystems, a company focused on diet-based manipulation of the gut microbiota, and BCD Biosciences, a company advancing novel bioactive glycans. Neither Evolve Biosystems nor BCD Biosciences had a role in the conceptualization, design, data collection, analysis or preparation of this paper. M.K. has a patent share on the diagnostic use of SNPs in ORMDL3 on chromosome 17q21. H.R. has received research support from DFG, BMBF, EU, Land Hessen, DAAD, ALK, Stiftung Pathobiochemie, Ernst-Wendt-Stiftung, Mead Johnson Nutritional and Beckman Coulter; speaker’s honoraria from Allergopharma, Novartis, Thermo Fisher, Danone, Mead Johnson Nutritional and Bencard; and consulting fees from Bencard and Sterna Biologicals. He is a cofounder of Sterna Biologicals. E.v.M. is listed as an inventor on the following patents: publication number EP 1411977, composition containing bacterial antigens used for the prophylaxis and treatment of allergic diseases, granted on 18 April 2007; publication number EP 1637147, stable dust extract for allergy protection, granted on 10 December 2008; publication number EP 1964570, pharmaceutical compound to protect against allergies and inflammatory diseases, granted on 21 November 2012. E.v.M. is listed as an inventor and has received royalties on the following patent: publication number EP 2361632, specific environmental bacteria for the protection from and/or treatment of allergic, chronic inflammatory and/or autoimmune disorders, granted on 19 March 2014. She has received funding and research support from FrieslandCampina; she has received consultation and speaker fees from OM Pharma, Böhringer Ingelheim International, Peptinnovate, Pharmaventures, Nestlé Deutschland (36 months before publication) and HiPP (future). M.J.E. is a co-inventor on patents for the use of environmental bacteria to prevent asthma (EP000001964570B1, US000009950017B2 and EP000002361632B1). His employer has received investigational products for an intervention study with minimally processed milk from FrieslandCampina.
Peer review information Alison Farrell was the primary editor on this article and managed its editorial process and peer review in collaboration with the rest of the editorial team.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
The current microbiome analysis population (n = 720) was selected based on available microbiome data at month 12. The French arm was not included because by design microbiome samples were not taken at month 2. The children with samples available at month 2 and 12 (n = 618) were quite equally distributed over the centers (Austria N = 139; Switzerland N = 205; Germany N = 136; Finland N = 138). For n = 102 children only 12 months samples were available. Subsamples are colored in red, blue, and white according to asthma status (yes, no, not available, respectively). The different subsamples colored in grey represent the basis of the respective figures of the main manuscript as indicated*. Samples with fungi data are a subsample of the 618 samples with bacteria, and only children with ITS samples at both time points available were analyzed**. Healthy controls were defined by no diarrhea between 2 and 12 months and no asthma / wheeze anytime; individuals with missing or implausible values for sampling time point were excluded (5 for bacteria, 1 for fungi)***. Butyryl-CoA:acetate CoA-transferase gene assay failed in 19 of the 157 samples (12%) for technical reasons.
a, Scatter plot of the first two axes of a principal coordinate analysis (PCoA) over both time points on ASV (amplicon sequence variants) levels. The values in brackets represent percentage of variance explained after correction of negative eigenvalues. b, Scatterplot of the first PCoA-axis against EMA. c,d, Associations of asthma phenotypes with EMA restricted to individuals not included when establishing the prediction model (n = 480 children), that is the 618 children with measurements at both time points minus the 138 healthy individuals. EMA is used as z-standardized continuous variable (c) and dichotomized at the lowest quartile (d).
Extended Data Fig. 3 Association of principal component axes of microbial composition at 2 and 12 months with asthma phenotypes and bacterial genera.
a, Associations of asthma phenotypes with the first five axes of a principle component analysis (PCA) at month 2. b, Correlation of the asthma-protective PCA-axis 3 at month 2 (7% variance explained) with single genera. c, Associations of asthma phenotypes with PCA-axes at month 12. d, Correlation of the asthma-protective PCA-axis 1 at month 12 (14% variance explained) with single genera. e–g, Mutually adjusted associations of EMA and the asthma-protective axes at both time points with asthma (e), atopic asthma (f), and non-atopic asthma (g). Associations are shown as odds ratios for the z-standardized variables.
Extended Data Fig. 4 Association of principle coordinate axes of microbial composition at 2 and 12 months with asthma phenotypes and bacterial genera.
Associations of asthma phenotypes of the first five axes of a principle coordinate analysis (PCoA) at month 2 a, and 12 c, using unweighted UniFrac as distance measure. Spearman correlations of the 10 most positively and 10 most negatively correlated individual genera with the asthma-protective PCoA-axes at month 2 b, and 12 d. Mutually adjusted models for EMA and the asthma-protective PCoA-axes at month 2 and 12 for asthma e, atopic asthma f, and nonatopic asthma g. Associations are shown as odds ratios for the z-standardized variables.
Extended Data Fig. 5 Correlation of estimated microbiome age (EMA) with asthma-protective axes and richness.
Relationship between EMA (x-axis) and various microbial measures (y-axis) including asthma-protective PCA- a, and PCoA-axes b, and bacterial richness c. The left column relates to 2 months, the right column to 12 months. As correlation coefficient Spearman’s rho is given.
Beta estimates of linear regression model of EMA versus duration of breastfeeding dichotomized at the indicated time points.
The upper panels a, refer to propionate, the lower panels b, to acetate. The left column gives proportion of asthma cases within quartiles of the respective short-chain fatty acid (SCFA) variables. The right column gives odds ratios with 95%-confidence intervals for the associations of asthma phenotypes with the respective dichotomous SCFA variables (upper quartiles versus lowest quartile). Propionate and acetate level designate measured SCFA levels, whereas the estimated scores refer to the prediction models of measured SCFA levels by the microbial composition.
a, Log-scaled box and whiskers plots of relative abundance of most common fungal taxa at month 2 and month 12 in 189 children. Lower and upper hinges of the boxes denote the first and third quartiles, respectively; the bold central line represents the median; the whiskers extend to the most extreme data point within 1.5 times the interquartile range from the hinges; extreme values lie beyond the whiskers and are marked by circles. Missing boxes indicate relative abundance < 0.5% at the respective time point. ‘(F)’, ‘(O)’, or ‘(P)’ stand for unclassified genera of the respective fungal family, order or phylum. b, Chronological age, that is the exact sampling time point in months plotted against estimated fungal age (EFA) illustrates that all chronologic information is largely removed from EFA. The density plot included in panel b reveals a skewed distribution of EFA. c, Fungal taxa most importantly predicting fungal age in the 35 healthy individuals. d, Determinants of EFA in the population with ITS data. Odds ratios are given with 95%-confidence intervals. Listed are determinants with p-values <0.01 in bivariate analyses; only consumption of any bread (shaded in gray) remains in a multivariable model. e, Associations of asthma phenotypes with EFA.
Asthma was defined as a doctor’s diagnosis of asthma or recurrent obstructive bronchitis. Asthma after 3 years was defined as a doctor’s diagnosis of asthma or recurrent obstructive bronchitis after the age of 3 years. The atopic and nonatopic phenotypes of asthma were defined by presence or absence of concomitant sensitization to inhalant allergens with specific IgE ≥ 0.7 IU/ml at age 6 years. Wheeze phenotypes were defined by a latent class analysis as previously performed14. Transient and intermediate wheeze were milder forms with better lung function and less medication. Persistent wheeze was related to genetic risk encoded on chromosome 17q21 and displayed reduced lung function. Lateonset wheeze was particularly associated with atopic sensitization and fraction of exhaled nitric oxide. Seasonal IgE was defined as at least one specific IgE to alder, birch, hazel, grass pollen, rye, mugwort, plantain, or alternaria ≥ 0.7 IU/ml at age 6 years. Perennial IgE (D. pteronyssinus, D. farinae, cat, horse, or dog) and food IgE (hen’s egg, cow’s milk, peanut, hazelnut, carrot or wheat flour) were defined in analogy.
PCA=principal component analysis, EMA=estimated microbiome age, EFA=estimated fungal age; p-values are derived from two-sided Kruskal-Wallis tests. The analyses were performed in all 618 individuals with data available for the respective measures, except for EFA, where data was available only in 189 individuals. Lower and upper hinges of the boxes denote the first and third quartiles, respectively; the bold central line represents the median; the whiskers extend to the most extreme data point within 1.5 times the interquartile range from the hinges; extreme values lie beyond the whiskers and are marked by circles.
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Depner, M., Taft, D.H., Kirjavainen, P.V. et al. Maturation of the gut microbiome during the first year of life contributes to the protective farm effect on childhood asthma. Nat Med 26, 1766–1775 (2020). https://doi.org/10.1038/s41591-020-1095-x
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