Immunological resilience and biodiversity for prevention of allergic diseases and asthma

Increase of allergic conditions has occurred at the same pace with the Great Acceleration, which stands for the rapid growth rate of human activities upon earth from 1950s. Changes of environment and lifestyle along with escalating urbanization are acknowledged as the main underlying causes. Secondary (tertiary) prevention for better disease control has advanced considerably with innovations for oral immunotherapy and effective treatment of inflammation with corticosteroids, calcineurin inhibitors, and biological medications. Patients are less disabled than before. However, primary prevention has remained a dilemma. Factors predicting allergy and asthma risk have proven complex: Risk factors increase the risk, while protective factors counteract them. Interaction of human body with environmental biodiversity with micro-organisms and biogenic compounds as well as the central role of epigenetic adaptation in immune homeostasis have given new insight. Allergic diseases are good indicators of the twisted relation to environment. In various non-communicable diseases, the protective mode of the immune system indicates low-grade inflammation without apparent cause. Giving microbes, pro- and prebiotics, has shown some promise in prevention and treatment. The real-world public health programme in Finland (2008-2018) emphasized nature relatedness and protective factors for immunological resilience, instead of avoidance. The nationwide action mitigated the allergy burden, but in the lack of controls, primary preventive effect remains to be proven. The first results of controlled biodiversity interventions are promising. In the fast urbanizing world, new approaches are called for allergy prevention, which also has a major cost saving potential.Peer reviewe

Twenty important research questions in microbial exposure and social equity

Social and political policy, human activities, and environmental change affect the ways in which microbial communities assemble and interact with people. These factors determine how different social groups are exposed to beneficial and/or harmful microorganisms, meaning microbial exposure has an important socioecological justice context. Therefore, greater consideration of microbial exposure and social equity in research, planning, and policy is imperative. Here, we identify 20 research questions considered fundamentally important to promoting equitable exposure to beneficial microorganisms, along with safeguarding resilient societies and ecosystems. The 20 research questions we identified span seven broad themes, including the following: (i) sociocultural interactions; (ii) Indigenous community health and well-being; (iii) humans, urban ecosystems, and environmental processes; (iv) human psychology and mental health; (v) microbiomes and infectious diseases; (vi) human health and food security; and (vii) microbiome-related planning, policy, and outreach. Our goal was to summarize this growing field and to stimulate impactful research avenues while providing focus for funders and policymakers

Garden soil bacteria transiently colonize gardeners' skin after direct soil contact

Abstract Urban soils provide a number of ecosystem services and health benefits, yet they are understudied compared with agricultural and wildland soils. Healthy soils host diverse microbiota, exposure to which may be critical for immune development and protection against chronic disorders, such as allergies and asthma. Gardening represents a key pathway for microbiota exposure, yet little is known about microbial community structure of urban garden soils, degree of soil‐to‐skin transfer during gardening, nor ability of soil microbes to persist on human skin. To explore these questions, we recruited 40 volunteers to collect soil samples from their gardens and a series of skin swab samples before and after gardening. Soil and skin bacterial communities were characterized using amplicon (16S) sequencing. Soil samples were also analyzed for chemical/physical characteristics. Soil bacterial communities had more alpha diversity and less beta diversity than skin communities, which varied greatly across individuals and within the same individual across time. The number of bacterial taxa shared between skin and garden soil increased immediately after gardening for most study participants. However, the imprint of garden soil largely disappeared within 12 hours. Despite this lack of persistence, a daily gardening routine with repeated and extended contact with soil likely reinoculates the skin such that soil microbes are often present, holding potential to impact health

Temporary establishment of bacteria from indoor plant leaves and soil on human skin

Abstract Background Plants are found in a large percentage of indoor environments, yet the potential for bacteria associated with indoor plant leaves and soil to colonize human skin remains unclear. We report results of experiments in a controlled climate chamber to characterize bacterial communities inhabiting the substrates and leaves of five indoor plant species, and quantify microbial transfer dynamics and residence times on human skin following simulated touch contact events. Controlled bacterial propagule transfer events with soil and leaf donors were applied to the arms of human occupants and repeatedly measured over a 24-h period using 16S rRNA gene amplicon sequencing. Results Substrate samples had greater biomass and alpha diversity compared to leaves and baseline skin bacterial communities, as well as dissimilar taxonomic compositions. Despite these differences in donor community diversity and biomass, we observed repeatable patterns in the dynamics of transfer events. Recipient human skin bacterial communities increased in alpha diversity and became more similar to donor communities, an effect which, for soil contact only, persisted for at least 24 h. Washing with soap and water effectively returned communities to their pre-perturbed state, although some abundant soil taxa resisted removal through washing. Conclusions This study represents an initial characterization of bacterial relationships between humans and indoor plants, which represent a potentially valuable element of biodiversity in the built environment. Although environmental microbiota are unlikely to permanently colonize skin following a single contact event, repeated or continuous exposures to indoor biodiversity may be increasingly relevant for the functioning and diversity of the human microbiome as urbanization continues

Architectural design drives the biogeography of indoor bacterial communities.

BackgroundArchitectural design has the potential to influence the microbiology of the built environment, with implications for human health and well-being, but the impact of design on the microbial biogeography of buildings remains poorly understood. In this study we combined microbiological data with information on the function, form, and organization of spaces from a classroom and office building to understand how design choices influence the biogeography of the built environment microbiome.ResultsSequencing of the bacterial 16S gene from dust samples revealed that indoor bacterial communities were extremely diverse, containing more than 32,750 OTUs (operational taxonomic units, 97% sequence similarity cutoff), but most communities were dominated by Proteobacteria, Firmicutes, and Deinococci. Architectural design characteristics related to space type, building arrangement, human use and movement, and ventilation source had a large influence on the structure of bacterial communities. Restrooms contained bacterial communities that were highly distinct from all other rooms, and spaces with high human occupant diversity and a high degree of connectedness to other spaces via ventilation or human movement contained a distinct set of bacterial taxa when compared to spaces with low occupant diversity and low connectedness. Within offices, the source of ventilation air had the greatest effect on bacterial community structure.ConclusionsOur study indicates that humans have a guiding impact on the microbial biodiversity in buildings, both indirectly through the effects of architectural design on microbial community structure, and more directly through the effects of human occupancy and use patterns on the microbes found in different spaces and space types. The impact of design decisions in structuring the indoor microbiome offers the possibility to use ecological knowledge to shape our buildings in a way that will select for an indoor microbiome that promotes our health and well-being

Offices contain significantly different dust microbial communities depending on ventilation source.

<p><b>a)</b> The first axis is constrained by whether or not offices have operable window louvers (blue) or not (red). Taxon names on either side are grouped from the 25 strongest weighting OTUs in either direction. <b>b)</b><i>Deinococcus</i> were 1.7 times more abundant in mechanically ventilated offices compared to window ventilated offices. <b>c)</b> The opposite pattern was observed for <i>Methylobacterium</i> OTUs, which were 1.8 times more abundant in window ventilated offices. Boxplots delineate (from bottom) minimum, Q1, median, Q3, and maximum values; notches indicate 95% confidence intervals. <b>d)</b> Cross-sectional view of representative Lillis Hall offices. Offices on the south side of the building (left) received primarily mechanically ventilated air, while offices on the north side of the building (right) are equipped with operable windows as a primary ventilation air source.</p

Architectural layout for two of four floors in Lillis Hall.

<p>Restrooms (brown), offices (blue) and classrooms (yellow) are shown to illustrate space type distribution throughout Lillis. The first two floors of the building are primarily devoted to classrooms and share a similar floor-plan. The 3rd and 4th floors contain most offices in the building and also share a similar floor-plan. The building has a basement and penthouse spaces; these are largely building support spaces, including mechanical rooms and storage.</p

Network analysis metrics used to quantify spatial arrangement of spaces within Lillis Hall.

<p>Examples in the left column follow classic network representation, while those in the right column embody the architectural translation of networks. Shaded nodes and building spaces correspond to centrality measures <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087093#pone.0087093-Freeman1" target="_blank">[22]</a> of <i>betweenness</i> (the number of shortest paths between all pairs of spaces that pass through a given space over the sum of all shortest paths between all pairs of spaces in the building) and <i>degree</i> (the number of connections a space has to other spaces); <i>connectance distance</i> (the number of doors between any two spaces) is a pairwise metric, shown here as the range of connectance distance values for each complete network/building. Since <i>betweenness</i> and <i>degree</i> strongly co-vary and are both measures of network centrality <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087093#pone.0087093-Freeman1" target="_blank">[22]</a>, they are considered together in some analyses.</p

Offices in Lillis Hall show a strong distance-decay pattern.

<p>When only considering a single space type, biological similarity (y-axis; 1 - Canberra distance) decreases with connectance distance (number of intermediate space boundaries [e.g., doors] one would walk through to travel the shortest distance between any two spaces) (Mantel test; <i>R</i> = 0.189; <i>P</i> = 0.002). The same pattern was also observed at the whole-building scale (not shown; Mantel test; <i>R</i> = 0.112; <i>P</i> = 0.001).</p

Dust communities within a building cluster by space type and are strongly correlated with building centrality and human occupancy.

<p>Points represent centroids (±SE) from distance based redundancy analysis (DB-RDA). Space types hold significantly different communities (<i>P</i> = 0.005), though this is driven primarily by restrooms. Bacterial OTUs that have the strongest influence in sample dissimilarities are shown at the margins; numbers in parentheses indicate multiple OTUs in the same genus. Centrality (along y-axis) represents network betweenness and degree; human occupancy (along x-axis) represents annual occupied hours and human diversity. All four correlates (simple linear models as a factor of ordination axis) are significant along their respective axes (all <i>P</i><0.001).</p