Search

Background The human skin microbiome is highly personalized, depending on, for example, body site, age, gender, and lifestyle factors. The temporal stability of an individual's skin microbiome-its resiliency and robustness over months and years-is also a personalized feature of the microbiome. The authors measured the temporal stability of the facial skin microbiome in a large cohort of subjects. In addition to measuring microbiome dynamics, they tracked facial skin condition using noninvasive, objective imaging and biophysical measures to identify significant facial features associated with temporal changes in microbiome diversity and composition. Methods The authors used 16S ribosomal RNA amplicon sequencing to track cheek and forehead skin microbiome diversity and composition annually over a 2-year period (2017-2019) in 115 healthy adult men and women. Skin metadata included facial features, such as wrinkles, hyperpigmentation, porphyrins, and skin color tone, as well as biophysical parameters for stratum corneum barrier function, pH, hydration, and elasticity. Results Across the subject population, the facial skin microbiome composition and diversity were relatively stable, showing minor variation over the 2-year period. However, for some subjects, composition, diversity, and relative abundance of specific organisms showed substantial changes from one year to the next, and these changes were associated with changes in stratum corneum barrier function and follicular porphyrins. Conclusions For healthy people, facial skin microbiome diversity and composition are relatively stable from year to year. Tracking the temporal changes in the microbiome along with skin phenotypic changes allows for a deeper understanding of the skin microbiome's role in health and disease. These results should be helpful in the design of longer-term intervention trials with microbiome-based skin care treatments.

The gut microbiome is a well-recognized modulator of host immunity, and its compositions differ between geographically separated human populations. Systemic innate immune responses to microbial derivatives also differ between geographically distinct human populations. However, the potential role of the microbiome in mediating geographically varied immune responses is unexplored. We here applied 16S amplicon sequencing to profile the stool microbiome and, in parallel, meas-ured whole-blood innate immune cytokine responses to several pattern recognition receptor (PRR) agonists among 2-year-old children across biogeographically diverse settings. Microbiomes differed mainly between high-and low-resource environments and were not strongly associated with other demographic factors. We found strong correlations between responses to Toll-like receptor 2 (TLR2) and relative abundances of Bacteroides and Prevotella populations, shared among Canadian and Ecuadorean children. Additional correlations between responses to TLR2 and bacterial populations were specific to individual geographic cohorts. As a proof of con-cept, we gavaged germfree mice with human donor stools and found murine sple-nocyte responses to TLR stimulation were consistent with responses of the corresponding human donor populations. This study identified differences in immune responses corre-lating to gut microbiomes across biogeographically diverse settings and evaluated biological plausibility using a mouse model. This insight paves the way to guide optimiza-tion of population-specific interventions aimed to improve child health outcomes. IMPORTANCE Both the gut microbiome and innate immunity are known to differ across biogeographically diverse human populations. The gut microbiome has been shown to directly influence systemic immunity in animal models. With this, modulation of the gut microbiome represents an attractive avenue to improve child health outcomes associated with altered immunity using population-specific approaches. However, there are very scarce data available to determine which members of the gut microbiome are associated with specific immune responses and how these differ around the world, creating a substantial barrier to rationally designing such interven-tions. This study addressed this knowledge gap by identifying relationships between distinct bacterial taxa and cytokine responses to specific microbial agonists across highly diverse settings. Furthermore, we provide evidence that immunomodulatory effects of region-specific stool microbiomes can be partially recapitulated in germfree mice. This is an important contribution toward improving global child health by targeting the gut microbiome., SCOPUS: ar.j, info:eu-repo/semantics/published

In both high-and low-income countries, HIV-negative children born to HIV-positive mothers (HIVexposed, uninfected [HEU]) are more susceptible to severe infection than HIV-unexposed, uninfected (HUU) children, with altered innate immunity hypothesized to be a cause. Both the gut microbiome and systemic innate immunity differ across biogeographically distinct settings, and the two are known to influence each other. And although the gut microbiome is influenced by HIV infection and may contribute to altered immunity, the biogeography of immune-microbiome correlations among HEU children have not been investigated. To address this, we compared the innate response and the stool microbiome of 2-y-old HEU and HUU children from Belgium, Canada, and South Africa to test the hypothesis that region-specific immune alterations directly correlate to differences in their stool microbiomes.We did not detect a universal immune or microbiome signature underlying differences between HEU versus HUU that was applicable to all children. But as hypothesized, population-specific differences in stool microbiomes were readily detected and included reduced abundances of short-chain fatty acid producing bacteria in Canadian HEU children. Furthermore, we did not identify innate immune-microbiome associations that distinguished HEU from HUU children in any population. These findings suggest that maternal HIV infection is independently associated with differences in both innate immunity and the stool microbiome in a biogeographical population-specific way., SCOPUS: ar.j, info:eu-repo/semantics/published

The mammalian gastrointestinal tract harbors a microbial community with metabolic activity critical for host health, including metabolites that can modulate effector functions of immune cells. Mice treated with vancomycin have an altered microbiome and metabolite profile, exhibit exacerbated T helper type 2 cell (Th2) responses, and are more susceptible to allergic lung inflammation. Here we show that dietary supplementation with short-chain fatty acids (SCFAs) ameliorates this enhanced asthma susceptibility by modulating the activity of T cells and dendritic cells (DCs). Dysbiotic mice treated with SCFAs have fewer interleukin-4 (IL4)-producing CD4+ T cells and decreased levels of circulating immunoglobulin E (IgE). In addition, DCs exposed to SCFAs activate T cells less robustly, are less motile in response to CCL19 in vitro, and exhibit a dampened ability to transport inhaled allergens to lung draining nodes. Our data thus demonstrate that gut dysbiosis can exacerbate allergic lung inflammation through both T cell- and DC-dependent mechanisms that are inhibited by SCFAs.

The COVID-19 pandemic has elevated concern about mask-related skin problems like so-called ‘maskne’ which is likely rooted in the skin microbiome. We therefore determined if wearing an N95 mask affects the skin microbiome in a 3-day controlled study. On Day 1, subjects (n=10) followed their normal office routine without a mask. On Days 2 and 3, subjects wore an N95 mask (3M Model 8210) from morning to late afternoon (6 hours). The same mask was used both days. Microbiome diversity and composition (16S rRNA amplicon sequencing, V1-V3), stratum corneum (SC) barrier function (TEWL), SC hydration, skin redness and follicular porphyrins were measured on the cheek (masked site) and forehead (control site) each morning and afternoon. At the end of the study, a sample of each mask was collected for microbiome analysis. Mask wearing showed no significant effect on alpha (Shannon) or beta (Brays-Curtis) microbiome diversity. Mask wearing had no significant effect on Cutibacterium acnes relative abundance. Mask wearing corresponded to a small increase in the genus Staphylococcus relative abundance on Day 2 (p=0.03) but not Day 3. There was no significant effect of mask wearing on SC hydration or follicular porphyrins. TEWL and skin redness were elevated (p

Asthma is a chronic disease of the airways affecting one in ten children in Westernized countries. Recently, our group showed that specific bacterial genera in early life are associated with atopy and wheezing in 1-year-old children. However, little is known about the link between the early life gut microbiome and the diagnosis of asthma in preschool age children. To determine the role of the gut microbiota in preschool age asthma, children up to 4 years of age enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) study were classified as asthmatic (n=39) or matched healthy controls (n=37). 16S rRNA sequencing and quantitative PCR (qPCR) were used to analyse the composition of the 3-month and 1-year gut microbiome of these children. At 3 months the abundance of the genus, Lachnospira (L), was decreased (P=0.008), whereas the abundance of the species, Clostridium neonatale (C), was increased (P=0.07) in asthmatics. Quartile analysis of stool composition at 3-months revealed a negative association between the ratio of these two bacteria (L/C) and asthma risk by 4 years of age [quartile 1: odds ratio (OR)=15, P=0.02, CI (confidence interval)= 1.8–124.7; quartile 2: OR=1.0, ns; quartile 3: OR=0.37, ns]. We conclude that opposing shifts in the relative abundances of Lachnospira and C. neonatale in the first 3 months of life are associated with preschool age asthma, and that the L/C ratio may serve as a potential early life biomarker to predict asthma development.

Many studies have highlighted the importance of body site and individuality in shaping the composition of the human skin microbiome, but we still have a poor understanding of how extrinsic (e.g., lifestyle) and intrinsic (e.g., age) factors influence its composition. We characterized the bacterial microbiomes of North American volunteers at four skin sites and the mouth. We also collected extensive subject metadata and measured several host physiological parameters. Integration of host and microbial features showed that the skin microbiome was predominantly associated with demographic, lifestyle, and physiological factors. Furthermore, we uncovered reproducible associations between chronological age, skin aging, and members of the genus Corynebacterium. Our work provides new understanding of the role of host selection and lifestyle in shaping skin microbiome composition. It also contributes to a more comprehensive appreciation of the factors that drive interindividual skin microbiome variation., Despite recognition that biogeography and individuality shape the function and composition of the human skin microbiome, we know little about how extrinsic and intrinsic host factors influence its composition. To explore the contributions of these factors to skin microbiome variation, we profiled the bacterial microbiomes of 495 North American subjects (ages, 9 to 78 years) at four skin surfaces plus the oral epithelium using 16S rRNA gene amplicon sequencing. We collected subject metadata, including host physiological parameters, through standardized questionnaires and noninvasive biophysical methods. Using a combination of statistical modeling tools, we found that demographic, lifestyle, and physiological factors collectively explained 12 to 20% of the variability in microbiome composition. The influence of health factors was strongest on the oral microbiome. Associations between host factors and the skin microbiome were generally dominated by operational taxonomic units (OTUs) affiliated with the Clostridiales and Prevotella. A subset of the correlations between microbial features and host attributes were site specific. To further explore the relationship between age and the skin microbiome of the forehead, we trained a Random Forest regression model to predict chronological age from microbial features. Age was associated mostly with two mutually coexcluding Corynebacterium OTUs. Furthermore, skin aging variables (wrinkles and hyperpigmented spots) were independently correlated to these taxa.

Background Allergic disease is the most frequent chronic health issue in children and has been linked to early-life gut microbiome dysbiosis. Many lines of evidence suggest that microbially derived short-chain fatty acids, and particularly butyrate, can promote immune tolerance. Objective We sought to determine whether bacterial butyrate production in the gut during early infancy is protective against the development of atopic disease in children. Methods We used shotgun metagenomic analysis to determine whether dysbiosis in butyrate fermentation could be identified in human infants, before their developing allergic disease. Results We found that the microbiome of infants who went on to develop allergic sensitization later in childhood lacked genes encoding key enzymes for carbohydrate breakdown and butyrate production. Conclusions Our findings support the importance of microbial carbohydrate metabolism during early infancy in protecting against the development of allergies.

Summary Gut microbial community properties of mammals are thought to be partly shaped by a combination of host immunity and environmental factors, but their relative importance is not firmly established. To address this gap, we first characterized the faecal bacteria of mice with a functioning immune system (wild-type, WT), mice with defective immune responses (CD45), mice lacking an adaptive immune system (RAG), and mice with both immune dysfunctions (45RAG). Using fingerprinting of 16S rRNA genes, we observed significant differences in gut microbiota composition across all mouse strains (P 0.05). Time-series analysis indicated that the communities of cohoused mice changed directionally as opposed to the relatively stable communities of non-cohoused controls. When we considered only taxonomic membership, it was the communities of CD45 non-cohoused mice that experienced the highest rate of change. Rather than be governed by fluctuations in the relative abundance of taxa, we suggest that CD45-regulated immune responses either are stimulated by the presence of bacteria per se or promote temporal stability by selecting for the occurrence of specific taxa.

Based on surface brushings and bronchoalveolar lavage fluid, Hilty and coworkers demonstrated microbiomes in the human lung characteristic of asthma and chronic obstructive pulmonary disease (COPD), which have now been confirmed by others.To extend these findings to human lung tissue samples.DNA from lung tissue samples was obtained from nonsmokers (n = 8); smokers without COPD (n = 8); patients with very severe COPD (Global Initiative for COPD [GOLD] 4) (n = 8); and patients with cystic fibrosis (CF) (n = 8). The latter served as a positive control, with sterile water as a negative control. All bacterial community analyses were based on polymerase chain reaction amplifying 16S rRNA gene fragments. Total bacterial populations were measured by quantitative polymerase chain reaction and bacterial community composition was assessed by terminal restriction fragment length polymorphism analysis and pyrotag sequencing.Total bacterial populations within lung tissue were small (20-1,252 bacterial cells per 1,000 human cells) but greater in all four sample groups versus the negative control group (P0.001). Terminal restriction fragment length polymorphism analysis and sequencing distinguished three distinct bacterial community compositions: one common to the nonsmoker and smoker groups, a second to the GOLD 4 group, and the third to the CF-positive control group. Pyrotag sequencing identified greater than 1,400 unique bacterial sequences and showed an increase in the Firmicutes phylum in GOLD 4 patients versus all other groups (P0.003) attributable to an increase in the Lactobacillus genus (P0.0007).There is a detectable bacterial community within human lung tissue that changes in patients with very severe COPD.

Asthma is the most prevalent pediatric chronic disease and affects more than 300 million people worldwide. Recent evidence in mice has identified a "critical window" early in life where gut microbial changes (dysbiosis) are most influential in experimental asthma. However, current research has yet to establish whether these changes precede or are involved in human asthma. We compared the gut microbiota of 319 subjects enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) Study, and show that infants at risk of asthma exhibited transient gut microbial dysbiosis during the first 100 days of life. The relative abundance of the bacterial genera Lachnospira, Veillonella, Faecalibacterium, and Rothia was significantly decreased in children at risk of asthma. This reduction in bacterial taxa was accompanied by reduced levels of fecal acetate and dysregulation of enterohepatic metabolites. Inoculation of germ-free mice with these four bacterial taxa ameliorated airway inflammation in their adult progeny, demonstrating a causal role of these bacterial taxa in averting asthma development. These results enhance the potential for future microbe-based diagnostics and therapies, potentially in the form of probiotics, to prevent the development of asthma and other related allergic diseases in children.

Large-scale mining for oil extraction in the Canadian boreal forest has prompted the need to assess the effectiveness of reclamation strategies on key biotic components of reconstructed soil profiles. Capitalizing on a network of long-term monitoring plots, we evaluated how enzyme activities and microbial community composition responded to reclamation of surface-mined soil in the Athabasca oil sands region of northern Alberta. Bulk soil (organic and mineral horizons) was sampled from undisturbed boreal forest sites and from sites representing seven reclamation prescriptions applied 30 years ago. Microbial community composition of both bacteria and fungi was determined with denaturing gradient gel electrophoresis (DGGE) and phospholipid fatty acid (PLFA) profiling. Microbial function was assessed by measuring the activities of β-glucosidase, β-xylosidase, phenoloxidase, peroxidase, phosphatase, chitinase, and urease. We found a general decrease in enzyme activities in reclaimed sites. Overburden (low-C) based prescriptions affected enzyme activities the most, causing a decrease in phenoloxidase activity (mineral horizon) in comparison to productive natural sites and an increase in β-glucosidase activity (organic horizon) in relation to nutrient-poor natural sites. Tailings-sand-based prescription enhanced microbial community dissimilarities with natural productive sites, although these were only evident with PLFA profiles. Effects of time-since-reclamation were not apparent, probably because they were masked by the larger influence of reclamation treatment. According to a principal components analysis of PLFA profiles, biomarker 18:1ω7c (Gram-negative) dominated in reclaimed sites and marker 18:1ω9c (fungi) was more abundant in natural sites. An increased fungal component in natural sites was presumably dominated by ectomycorrhizae, as suggested by sequencing of ITS regions. Non-parametric multivariate multiple regression indicated that the fungal-to-bacterial-biomass ratio largely explained the overall variation in PLFA profiles of reclaimed sites, whereas in natural sites soil nitrogen explained most of the community structure variability. Soil pH and woody debris accumulation emerged as significant explanatory variables when all sites were analyzed together. In contrast to PLFA profiles, DGGE profiles revealed significant regional-scale spatial structuring within reclaimed sites (organic horizon) and in natural sites (mineral horizon). Our results indicate that the response of abundant microbial populations to reclamation is likely governed by soil abiotic properties and, indirectly, by the effects of reclamation on plant growth.

Our current knowledge on the relevance of microbial diversity and composition for the recovery and maintenance of soil biological processes is rudimentary, partly because experimental substantiation of the importance of community composition to function is scarce. Guided by this gap, we devised a reciprocal transplant experiment to examine the functional behaviour of different microbial communities exposed to two structurally distinct peats. Sterile peat samples representing two types, one humified (sedge) and the other dominated by coarse plant material (fibric), were inoculated with a 10−1, 10−3, 10−5, or 10−8 dilution of either the same or reciprocal peats. After 5 months of incubation, we used a nucleotide-analog technique to label the active bacterial taxa in samples receiving the 10−1 and 10−8 dilutions. We assessed both the peats' functional potential (respiration and nutrient-acquiring and lignin-degrading enzyme activities) and the structures of active and total bacterial communities (PCR-DGGE). In general, we found a decline in respiration rates and increase in enzyme activities with increasing dilution level, but the effect of dilution on bacterial richness was weak. The bacterial community structure and richness depended on both the inoculum source and the peat type. The activity of enzymes involved in nutrient acquisition depended mainly on the soil type, while the lignin-degrading activity was influenced by differences in community composition between peat types. Neither active bacterial populations nor respiration were significantly influenced by peat type or inoculum source. Our results suggest that the relationship between microbial community composition and function is not only related to the taxonomic breadth of the taxa that perform a given function, but may also be shaped by interactions between microorganisms in the inoculum source and the substrate being colonized.

Stability of laccase isoenzymes from a crude extract obtained from Fomes sclerodermeus grown on wheat bran medium was studied. The variables assessed were temperature, pH and additives. As revealed by PAGE, three bands of laccase, each with different thermal inactivation pattern, were detected in the crude extract: after 6 h at 50 °C and pH 8, Lc2 was the most resistant, while the Lc1 and Lc3 bands were almost completely inactivated. This pattern of inactivation was observed at all temperatures and pH tested. Laccase activity was more stable in the 5-10 pH range when incubated at 40 and 50 °C; at 30 °C and 24 h the enzyme remained fully active in the 3-11 pH range. The effect of additives (veratryl alcohol, trehalose, glycerol, mannitol, glutaraldehyde, CuSO4 and 1-HBT) on laccase stability was tested. The stability was enhanced with CuSO4 (1.25 mM), glycerol (0.2%) and mannitol (1%). The presence of both CuSO4 and glycerol caused a 3-fold increase in the half-life values. Fil: Papinutti, Víctor Leandro. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentina Fil: Dimitriu, Pedro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina Fil: Forchiassin, Flavia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina

Background: Previously our group associated early life gut microbial alterations in one-year-old children with risk of active asthma at school age. These early life alterations were characterized by significant reductions in four bacterial genera and a decreased production of microbial derived metabolites. We hypothesize that this early life gut microbial dysbiotic state is also associated with asthma diagnosed in children by three years of age and aim to identify additional bacterial populations that might be contributing to this asthmatic phenotype. Methods: 286 children enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) study were classified according to the diagnosis of asthma by three years of age. Bacterial 16S rDNA from 3-month and 1-year stool samples from these children was extracted, amplified, and subjected to high throughput Illumina sequencing. Bacterial genera were quantified by quantitative PCR in 16S rDNA samples from all asthmatic children and a subset of controls. An exact logistic regression model was used to assess the effects of potentially confounding variables (i.e. antibiotic exposure, mode of birth). Results: 16S sequence analysis of our sample cohort (286 subjects) identified differentially abundant bacterial populations between asthmatics and controls at 3-months of age. Additionally, qPCR identified significant shifts in the abundance of specific bacterial genera at 3-months and 1-year of age in the asthmatic group when compared to controls. Conclusions: Shifts in the relative abundance of certain gut bacterial populations in early life are associated with asthma diagnosed in children by three years of age.

The relatively sparse but diverse microbiome in human lungs may become less diverse in chronic obstructive pulmonary disease (COPD). This article examines the relationship of this microbiome to emphysematous tissue destruction, number of terminal bronchioles, infiltrating inflammatory cells, and host gene expression.Culture-independent pyrosequencing microbiome analysis was used to examine the V3-V5 regions of bacterial 16S ribosomal DNA in 40 samples of lung from 5 patients with COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 4) and 28 samples from 4 donors (controls). A second protocol based on the V1-V3 regions was used to verify the bacterial microbiome results. Within lung tissue samples the microbiome was compared with results of micro-computed tomography, infiltrating inflammatory cells measured by quantitative histology, and host gene expression.Ten operational taxonomic units (OTUs) was found sufficient to discriminate between control and GOLD stage 4 lung tissue, which included known pathogens such as Haemophilus influenzae. We also observed a decline in microbial diversity that was associated with emphysematous destruction, remodeling of the bronchiolar and alveolar tissue, and the infiltration of the tissue by CD4(+) T cells. Specific OTUs were also associated with neutrophils, eosinophils, and B-cell infiltration (P 0.05). The expression profiles of 859 genes and 235 genes were associated with either enrichment or reductions of Firmicutes and Proteobacteria, respectively, at a false discovery rate cutoff of less than 0.1.These results support the hypothesis that there is a host immune response to microorganisms within the lung microbiome that appears to contribute to the pathogenesis of COPD.

Background Resident gut microbiota are now recognized as potent modifiers of host immune responses in various scenarios. Recently, we demonstrated that perinatal exposure to vancomycin, but not streptomycin, profoundly alters gut microbiota and enhances susceptibility to a T H 2 model of allergic asthma. Objective Here we sought to further clarify the etiology of these changes by determining whether perinatal antibiotic treatment has a similar effect on the T H 1/T H 17-mediated lung disease, hypersensitivity pneumonitis. Methods Hypersensitivity pneumonitis was induced in C57BL/6 wild-type or recombination-activating gene 1–deficient mice treated perinatally with vancomycin or streptomycin by repeated intranasal administration of Saccharopolyspora rectivirgula antigen. Disease severity was assessed by measuring lung inflammation, pathology, cytokine responses, and serum antibodies. Microbial community analyses were performed on stool samples via 16S ribosomal RNA pyrosequencing and correlations between disease severity and specific bacterial taxa were identified. Results Surprisingly, in contrast to our findings in an allergic asthma model, we found that the severity of hypersensitivity pneumonitis was unaffected by vancomycin, but increased dramatically after streptomycin treatment. This likely reflects an effect on the adaptive, rather than innate, immune response because the effects of streptomycin were not observed during the early phases of disease and were abrogated in recombination-activating gene 1–deficient mice. Interestingly, Bacteroidetes dominated the intestinal microbiota of streptomycin-treated animals, while vancomycin promoted the expansion of the Firmicutes . Conclusions Perinatal antibiotics exert highly selective effects on resident gut flora, which, in turn, lead to very specific alterations in susceptibility to T H 2- or T H 1/T H 17-driven lung inflammatory disease.

Gut microbial community properties of mammals are thought to be partly shaped by a combination of host immunity and environmental factors, but their relative importance is not firmly established. To address this gap, we first characterized the faecal bacteria of mice with a functioning immune system (wild-type, WT), mice with defective immune responses (CD45), mice lacking an adaptive immune system (RAG), and mice with both immune dysfunctions (45RAG). Using fingerprinting of 16S rRNA genes, we observed significant differences in gut microbiota composition across all mouse strains (P 0.001) and identified several mouse strain-specific genera via pyrosequencing, including Turicibacter sp. (in WT mice) and Allobaculum sp. (in CD45-deficient animals). To define the role of the host immune system in constraining gut microbiota stability after perturbation, we cohoused CD45-deficient and WT mice and monitored gut bacterial community dynamics during 8 weeks. Cohousing caused the WT bacterial communities to become indistinguishable from those of CD45 mice (P 0.05). Time-series analysis indicated that the communities of cohoused mice changed directionally as opposed to the relatively stable communities of non-cohoused controls. When we considered only taxonomic membership, it was the communities of CD45 non-cohoused mice that experienced the highest rate of change. Rather than be governed by fluctuations in the relative abundance of taxa, we suggest that CD45-regulated immune responses either are stimulated by the presence of bacteria per se or promote temporal stability by selecting for the occurrence of specific taxa.

Productivity gradients in the boreal forest are largely determined by regional-scale changes in soil conditions, and bacterial communities are likely to respond to these changes. Few studies, however, have examined how variation in specific edaphic properties influences the composition of soil bacterial communities along environmental gradients. We quantified bacterial compositional diversity patterns in ten boreal forest sites of contrasting fertility. Bulk soil (organic and mineral horizons) was sampled from sites representing two extremes of a natural moisture-nutrient gradient and two distinct disturbance types, one barren and the other vegetation-rich. We constructed 16S rRNA gene clone libraries to characterize the bacterial communities under phylogenetic- and species-based frameworks. Using a nucleotide analog to label DNA-synthesizing bacteria, we also assessed the composition of active taxa in disturbed sites. Most sites were dominated by sequences related to the alpha-Proteobacteria, followed by acidobacterial and betaproteobacterial sequences. Non-parametric multivariate regression indicated that pH, which was lowest in the natural sites, explained 34% and 16% of the variability in community structure as determined by phylogenetic-based (UniFrac distances) and species-based (Jaccard similarities) metrics, respectively. Soil pH was also a significant predictor of richness (Chao1) and diversity (Shannon) measures. Within the natural edaphic gradient, soil moisture accounted for 32% of the variance in phylogenetic (but not species) community structure. In the boreal system we studied, bacterial beta-diversity patterns appear to be largely related to "master" variables (e.g., pH, moisture) rather than to observable attributes (e.g., plant cover) leading to regional-scale fertility gradients.

The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing iron-reducing bacteria, as well as fermentative microorganisms, were also found, whereas the numbers of methanogens were low or methanogens were undetectable. The bacterial community composition of summer and fall samples was also assessed by constructing 16S rRNA gene clone libraries. A total of 508 sequences represented an estimated >1,100 unique operational taxonomic units, most of which were from the monimolimnion, and the summer samples were more diverse than the fall samples (Chao1 = 530 and Chao1 = 295, respectively). For both seasons, the mixolimnion sequences were dominated by Gammaproteobacteria , and the chemocline and monimolimnion libraries were dominated by members of the low-G+C-content group, followed by the Cytophaga-Flexibacter-Bacteroides (CFB) group; the mixolimnion sediments contained sequences related to uncultured members of the Chloroflexi and the CFB group. Community overlap and phylogenetic analyses, however, not only demonstrated that there was a high degree of spatial turnover but also suggested that there was a degree of temporal variability due to differences in the members and structures of the communities.

A1 Role of fibrocytes in allergic rhinitis Marie-Ève Côté, Marie-Ève Boulay, Sophie Plante, Jamila Chakir, Louis-Philippe Boulet A2 Patterns of aeroallergens sensitization in Northern Alberta Hanan Ahmed, Maria-Beatriz Ospina, Kyriaki Sideri, Harissios Vliagoftis A3 Addressing acceptable risk for adolescents with Food-Induced Anaphylaxis (FIA) Sara F. Johnson, Roberta L. Woodgate A4 Outcomes of matched related and unrelated bone marrow transplantation after reduced-toxicity conditioning for children suffering from Chronic Granulomatous Disease Guilhem Cros, Pierre Teira, Sonia Cellot, Henrique Bittencourt, Helene Decaluwe, Marie France Vachon, Michel Duval, Elie Haddad A5 Outcomes of patients with severe combined immunodeficiency (SCID) prior to and after initiation of newborn screening for SCID in Ontario Vy H.D. Kim, Anne Pham-Huy, Eyal Grunebaum A6 Detection of regulatory B cells in the airways of subjects with asthma John-Paul Oliveria, Stephanie Phan, Mark W. Tenn, Damian Tworek, Steven G. Smith, Adrian J. Baatjes, Caitlin D. Obminski, Caroline E. Munoz, Tara X. Scime, Roma Sehmi, Gail M Gauvreau A7 Characterization of IgE-expressing B cells in the airways and peripheral blood of allergic asthmatic subjects John-Paul Oliveria, Stephanie Phan, Mark W. Tenn, Brittany M Salter, Steven G Smith, Caitlin D Obminski, Caroline E Munoz, Abbey Schlatman, Tara X Scime, Rick Watson, Roma Sehmi, Gail M Gauvreau A8 Pregnancy: could it be a risk factor for primary immunodeficient patients Roya Sherkat, Razieh Khoshnevisan, Saba Sheikhbahaei A9 Clinical experience with Octagam: a Canadian retrospective chart review Stephen Betschel, Richard Warrington, Robert Schellenberg A10 Kounis syndrome secondary to contrast media with inferior ST elevations and bilateral ischemic stroke Michael N Fein, Jean-Philippe Pelletier A11 Honey bee venom immunotherapy ineffective in bumble bee-induced anaphylaxis: case report and review of literature Manstein Kan, Robert Schellenberg A12 Delayed immune reconstitution occurring after multiple immune complications of hematological stem cell transplantation for a leaky SCID Roxane Labrosse, Guilhem Cros, Pierre Teira, Henrique Bittencourt, Helene Decaluwe, Michel Duval, Elie Haddad A13 Comparison of Three Case Reports of Acquired Angioedema: presentation, management and outcome Raymond Mak, James Loh, Amin Kanani A14 Sitagliptin-associated angioedema not related to concurrent use of ARB or ACE inhibitor Dominik A. Nowak, Paul K. Keith A15 Sneddon-Wilkinson subcorneal pustular dermatosis associated with an IgA monoclonal gammopathy Daniel Pannozzo, Dominik A. Nowak, Hermenio C. Lima A16 Omalizumab can be effective in patients with allergic bronchopulmonary aspergillosis Diana Pham, Hoang Pham, Gonzalo G. Alvarez, Istvan T. Bencze, Krishna B. Sharma, Mark Smith, Shawn Aaron, Jennifer Block, Tara Keays, Judith Leech, David Schneidermen, Jodi Cameron, Jennifer Forgie, Alicia Ring, John W. O’Quinn, Stephanie Santucci, William H. Yang A17 Efficacious use of omalizumab in the treatment of cystic fibrosis Diana Pham, Hoang Pham, Ena Gaudet, Shawn Aaron, Stephanie Santucci, William H. Yang A18 HAE with normal C1-INH with inconsistent response to C1 esterase inhibitor infusion but reliably responsive to icatibant Hoang Pham, Stephanie Santucci, William H. Yang A19 Anaphylaxis reaction to lactase enzyme Mathew R. Voisin, Rozita Borici-Mazi A20 Risk of solid tumor malignancies in patients with primary immune deficiency Kateryna Vostretsova, Donald F. Stark A21 Is it time to adopt the chromogenic assay for measuring C1 esterase inhibitor function in patients with HAE Type 2? Elizabeth Yeboah, Paul K. Keith A22 Emergency department visits for anaphylaxis and allergic reactions Michelle Martin-Rhee, Cheryl Gula, Clare Cheng, Geoff Paltser A23 START: Susceptibility To food Allergies in a Registry of Twins Alizée Dery, Ann Clarke, Kari Nadeau, Laurie Harada, Kimberley Weatherall, Celia Greenwood, Denise Daley, Yuka Asai, Moshe Ben-Shoshan A24 Qualifying the diagnostic approach employed by allergists when managing patients with self-diagnosed non-celiac gluten sensitivity (NCGS) Lee Horgan, Teresa Pun A25 Retrospective analysis on the agreement between skin prick test and serum food specific IgE antibody in adults with suspected food allergy Ling Ling, Maria B. Ospina, Kyriaki Sideri, Harissios Vliagoftis A26 Staple food hypersensitivity from infancy to adolescence: a report from the BAMSE cohort Jennifer L.P. Protudjer, Mirja Vetander, Marianne van Hage, Ola Olén, Magnus Wickman, Anna Bergström A27 Evaluating the impact of supervised epinephrine autoinjector administration during food challenges on perceived parent confidence Timothy Teoh, Christopher Mill, Tiffany Wong, Ingrid Baerg, Angela Alexander, Kyla J. Hildebrand, John Dean, Boris Kuzeljevic, Edmond S. Chan A28 Local immunoglobulin production to Aspergillus fumigatus cystic fibrosis Jonathan Argeny, Mia Gona-Hoepler, Petra Fucik, Edith Nachbaur, Saskia Gruber, Reto Crameri, Andreas Glaser, Zsolt Szépfalusi, Claudio Rhyner, Thomas Eiwegger A29 Extract consumption with skin prick test (SPT) devices Greg. Plunkett, Brad Mire A30 Evaluation of our cases with nonsteroidal anti-inflammatory drug reactions Mehtap Yazicioglu, Ceren Can, Gokce Ciplak A31 Reasons for referral and final diagnoses in a tertiary care pediatric allergy clinic Victoria E. Cook, Kyla J. Hildebrand, Elodie Portales-Casamar, Christopher Mill, Edmond S. Chan A32 Internist referral practices for inpatients with self-reported penicillin allergies at a tertiary care teaching hospital Michael N Fein, Emil P Nashi A33 Assessing the risk of reactions in children with a negative oral challenge after a subsequent use of amoxicillin Sofianne Gabrielli, Christopher Mill, Marie-Noel Primeau, Christine Lejtenyi, Elena Netchiporouk, Alizee Dery, Greg Shand, Moshe Ben-Shoshan A34 Validity of self-reported penicillin allergies Erica Hoe, Joel Liem A35 Effectiveness of allergy-test directed elimination diets in eosinophilic esophagitis Jason K. Ko, David J.T. Huang, Jorge A. Mazza A36 Allergy testing and dietary management in pediatric eosinophilic esophagitis (EoE): A retrospective review of a tertiary Canadian centre’s experience Mary McHenry, Anthony Otley,Wade Watson A37 Visualizing the impact of atopic and allergic skin disease Dominik A. Nowak, John N. Kraft A38 Cystic fibrosis with and without nasal polyposis in pediatric patients: a cross-sectional comparative study Mihaela Paina, Ahmed A. Darwish Hassan, Delia Heroux, Lynn Crawford, Gail Gauvreau, Judah Denburg, Linda Pedder, Paul K. Keith A39 Evaluation of macrolide antibiotic hypersensitivity: the role of oral challenges in children Bahar Torabi, Marie-Noel Primeau, Christine Lejtenyi, Elaine Medoff, Jennifer Mill, Moshe Ben-Shoshan A40 Venom allergy testing: is a graded approach necessary? Jaclyn A. Quirt, Xia Wen, Jonathan Kim, Angel Jimenez Herrero, Harold L. Kim A41 The role of oral challenges in evaluating cephalosporin hypersensitivity reactions in children Magdalena J. Grzyb, Marie-Noël Primeau, Christine Lejtenyi, Elaine Medoff, Jennifer Mill, Moshe Ben-Shoshan A42 Breastfeeding and infant wheeze, atopy and atopic dermatitis: findings from the Canadian Healthy Infant Longitudinal Development Study Meghan B. Azad, Zihang Lu, Allan B. Becker, Padmaja Subbarao, Piushkumar J. Mandhane, Stuart E. Turvey, Malcolm R. Sears, the CHILD Study Investigators A43 IL33 DNA methylation in bronchial epithelial cells is associated to asthma Anne-Marie Boucher-Lafleur, Valérie Gagné-Ouellet, Éric Jacques, Sophie Plante, Jamila Chakir, Catherine Laprise A44 NRF2 mediates the antioxidant response to organic dust-induced oxidative stress in bronchial epithelial cells Michael Chen, Toby McGovern, Mikael Adner, James G. Martin A45 The effects of perinatal distress, immune biomarkers and mother-infant interaction quality on childhood atopic dermatitis (rash) at 18 months Nela Cosic, Henry Ntanda, Gerald Giesbrecht, Anita Kozyrskyj, Nicole Letourneau A46 Examining the immunological mechanisms associated with cow’s milk allergy Bassel Dawod, Jean Marshall A47 Tryptase levels in children presenting with anaphylaxis to the Montréal Children’s Hospital Sarah De Schryver, Michelle Halbrich, Ann Clarke, Sebastian La Vieille, Harley Eisman, Reza Alizadehfar, Lawrence Joseph, Judy Morris, Moshe Ben-Shoshan A48 Secondhand tobacco smoke exposure in infancy and the development of food hypersensitivity from childhood to adolescence Laura Y. Feldman, Jesse D. Thacher, Inger Kull, Erik Melén, Göran Pershagen, Magnus Wickman, Jennifer L. P. Protudjer, Anna Bergström A49 Combined exposure to diesel exhaust and allergen enhances allergic inflammation in the bronchial submucosa of atopic subjects Ali Hosseini, Tillie L. Hackett, Jeremy Hirota, Kelly McNagny, Susan Wilson, Chris Carlsten A50 Comparison of skin-prick test measurements by an automated system against the manual method Saiful Huq, Rishma Chooniedass, Brenda Gerwing, Henry Huang, Diana Lefebvre, Allan Becker A51 The accurate identification and quantification of urinary biomarkers of asthma and COPD through the use of novel DIL- LC-MS/MS methods Mona M. Khamis, Hanan Awad, Kevin Allen, Darryl J. Adamko, Anas El-Aneed A52 Systemic immune pathways associated with the mechanism of Cat-Synthetic Peptide Immuno-Regulatory Epitopes, a novel immunotherapy, in whole blood of cat-allergic people Young Woong Kim, Daniel R. Gliddon, Casey P. Shannon, Amrit Singh, Pascal L. C. Hickey, Anne K. Ellis, Helen Neighbour, Mark Larche, Scott J. Tebbutt A53 Reducing the health disparities: online support for children with asthma and allergies from low-income families Erika Ladouceur, Miriam Stewart, Josh Evans, Jeff Masuda, Nicole Letourneau, Teresa To, Malcolm King A54 Epigenetic association of PSORS1C1 and asthma in the Saguenay-Lac-Saint-Jean asthma study Miriam Larouche, Liming Liang, Catherine Laprise A55 IL-33 induces cytokine and chemokine production in human mast cells Stephanie A. Legere, Ian D. Haidl, Jean-Francois Legaré, Jean S. Marshall A56 Reference ranges for lung clearance index from infancy to adolescence for Canadian population Zihang Lu, Malcolm Sears, Theo J. Moraes, Felix Ratjen, Per Gustafsson, Wendy Lou, Padmaja Subbarao A57 Kingston Allergy Birth Cohort: cohort profile and mother/child characteristics to age 2 Michelle L. North, Elizabeth Lee, Vanessa Omana, Jenny Thiele, Jeff Brook, Anne K. Ellis A58 Cow’s milk protein specific IgE, IgA and IgG4 as a predictor of outcome in oral immunotherapy Tanvir Rahman, Duncan Lejtenyi, Sarah De Schryver, Ryan Fiter, Ciriaco Piccirillo, Moshe Ben-Shoshan, Bruce Mazer A59 Age of peanut introduction and development of reactions and sensitization to peanut Elinor Simons, Allan B. Becker, Rishma Chooniedass, Kyla Hildebrand, Edmond S. Chan, Stuart Turvey, Padmaja Subbarao, Malcolm Sears A60 Multi-omic blood biomarker signatures of the late phase asthmatic response Amrit Singh, Casey P. Shannon, Young Woong Kim, Mari DeMarco, Kim-Anh Le Cao, Gail M. Gauvreau, J. Mark FitzGerald, Louis-Philippe Boulet, Paul M. O’Byrne, Scott J. Tebbutt A61 Early life gut microbial alterations in children diagnosed with asthma by three years of age Leah T. Stiemsma, Marie-Claire Arrieta, Jasmine Cheng, Pedro A. Dimitriu, Lisa Thorson, Sophie Yurist, Boris Kuzeljevic, Diana L. Lefebvre, Padmaja Subbarao, Piush Mandhane, Allan Becker, Malcolm R. Sears, Kelly M. McNagny, Tobias Kollmann, the CHILD Study Investigators, William W. Mohn, B. Brett Finlay, Stuart E. Turvey A62 The relationship between food sensitization and atopic dermatitis at age 1 year in a Canadian birth cohort Maxwell M. Tran, Diana L. Lefebvre, Chinthanie F. Ramasundarahettige, Allan B. Becker, Wei Hao Dai, Padmaja Subbarao, Piush J. Mandhane, Stuart E. Turvey, Malcolm R. Sears A63 Allergen inhalation enhances Toll-like receptor-induced thymic stromal lymphopoietin receptor expression by hematopoietic progenitor cells in mild asthmatics Damian Tworek, Delia Heroux, Seamus N. O’Byrne, Paul M. O’Byrne, Judah A. Denburg A64 The Allergic Rhinitis Clinical Investigator Collaborative – replicated eosinophilia on repeated cumulative allergen challenges in nasal lavage samples Laura Walsh, Mena Soliman, Jenny Thiele, Lisa M. Steacy, Daniel E. Adams, Anne K. Ellis A65 The CHILD Study: optimizing subject retention in pediatric longitudinal cohort research Linda Warner, Mary Ann Mauro, Robby Mamonluk, Stuart E. Turvey A66 Differential expression of C3a and C5a in allergic asthma ChenXi Yang, Amrit Singh, Casey P. Shannon, Young Woong Kim, Ed M. Conway, Scott J. Tebbutt

Background Asthma is a chronic inflammatory disease characterized by bronchial hyper-responsiveness [1]. As the most endemic of all childhood diseases, asthma accounts for the majority of hospitalizations and school absences in children [2]. Exciting new research focuses on the involvement of the gut microbiome in asthma development. Murine studies support the hypothesis that the administration of probiotics or antibiotics during post-natal life alters the gut microbiome and ultimately the asthmatic symptoms of these mice [3-5]. This study will translate these findings into humans using stool samples obtained from the Canadian Healthy Infant Longitudinal Development (CHILD) study.