The Neonatal Microbiome and Necrotizing Enterocolitis.

Necrotizing enterocolitis (NEC) is a devastating disorder that affects approximately 10% of premature infants. Its mortality remains high (15-30%), and its cause remains unknown. About 80% of cases occur within 35 days of birth among hospitalized newborns of low birth weight. Probiotics diminish the incidence and severity of NEC, and NEC does not occur antepartum. NEC affects a readily identifiable at-risk group, has a tightly defined interval before its onset, occurs in an organ system that is intimately associated with a microbial population in flux, has a plausible association with the intestinal microbiota, and cohorts at risk have rarely been studied in large numbers, or prospectively. This disorder, therefore, provides a unique opportunity to explore the role of the human enteric microbiome in a devastating disease. Moreover, NEC epidemiology and age-incidence present an ability to enroll and study cohorts that are highly likely to provide valuable pathophysiologic and microbiologic insights.

In this project, we will identify and quantify the microbial components of stool and its products before and at the onset of NEC. In doing so, we will test the overarching hypothesis that NEC is a direct or indirect consequence of the enteric biomass, its products, or both. We will use multicenter cohorts of premature infants at high risk of developing NEC, extend our research on this disease currently sponsored by the Washington University Institute of Clinical and Translational Sciences, and continue our longstanding collaborations with the Genome Center at Washington University and the Washington University Digestive Diseases Research Core Center (Informatics Core). The Aims of this proposal are to (1) conduct a case cohort study in which we compare clinical data and biological specimens from cases and well-matched controls; (2) determine if the kind and density of intestinal biomass, its gene content, and transcriptional activity are associated with, and potential determinants of, NEC; and (3) determine if host risk alleles for intestinal inflammation play a role in the development of NEC. These efforts will be accomplished using subjects from three collaborating neonatal intensive care units (NICUs), focusing on the critical, instructive, and understudied pre-NEC stage of illness, and formulating a data repository that will be a resource for investigators worldwide who wish to focus their efforts on NEC, its precipitants, and its prevention and cure.
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The Human Virome in Children and its Relationship to Febrile Illness

This study investigates the relationship of viruses to febrile illness in children. Subjects are normal children 2-36 months of age with fever along with normal children of the same age without fever, plus immunocompromised children with fever along with immunocompromised children without fever. Specimens obtained include blood, nasopharyngeal secretions, and feces. Specimens are analyzed using a panel of virus-specific PCR assays and also by high throughput sequencing using 454 and Illumina platforms

Genome sequences of 15 Gardnerella vaginalis strains isolated from the vaginas of women with and without bacterial vaginosis

Gardnerella vaginalis is a predominant species in bacterial vaginosis, a dysbiosis of the vagina that is associated with adverse health outcomes, including preterm birth. Here, we present the draft genome sequences of 15 Gardnerella vaginalis strains (now available through BEI Resources) isolated from women with and without bacterial vaginosis

New statistical method identifes cytokines that distinguish stool microbiomes

Regressing an outcome or dependent variable onto a set of input or independent variables allows the analyst to measure associations between the two so that changes in the outcome can be described by and predicted by changes in the inputs. While there are many ways of doing this in classical statistics, where the dependent variable has certain properties (e.g., a scalar, survival time, count), little progress on regression where the dependent variable are microbiome taxa counts has been made that do not impose extremely strict conditions on the data. In this paper, we propose and apply a new regression model combining the Dirichlet-multinomial distribution with recursive partitioning providing a fully non-parametric regression model. This model, called DM-RPart, is applied to cytokine data and microbiome taxa count data and is applicable to any microbiome taxa count/metadata, is automatically fit, and intuitively interpretable. This is a model which can be applied to any microbiome or other compositional data and software (R package HMP) available through the R CRAN website

Metagenomic analysis of double-stranded DNA viruses in healthy adults

BackgroundThe Human Microbiome Project (HMP) was undertaken with the goal of defining microbial communities in and on the bodies of healthy individuals using high-throughput, metagenomic sequencing analysis. The viruses present in these microbial communities, the `human virome¿, are an important aspect of the human microbiome that is particularly understudied in the absence of overt disease. We analyzed eukaryotic double-stranded DNA (dsDNA) viruses, together with dsDNA replicative intermediates of single-stranded DNA viruses, in metagenomic sequence data generated by the HMP. 706 samples from 102 subjects were studied, with each subject sampled at up to five major body habitats: nose, skin, mouth, vagina, and stool. Fifty-one individuals had samples taken at two or three time points 30 to 359 days apart from at least one of the body habitats.ResultsWe detected an average of 5.5 viral genera in each individual. At least 1 virus was detected in 92% of the individuals sampled. These viruses included herpesviruses, papillomaviruses, polyomaviruses, adenoviruses, anelloviruses, parvoviruses, and circoviruses. Each individual had a distinct viral profile, demonstrating the high interpersonal diversity of the virome. Some components of the virome were stable over time.ConclusionsThis study is the first to use high-throughput DNA sequencing to describe the diversity of eukaryotic dsDNA viruses in a large cohort of normal individuals who were sampled at multiple body sites. Our results show that the human virome is a complex component of the microbial flora. Some viruses establish long-term infections that may be associated with increased risk or possibly with protection from disease. A better understanding of the composition and dynamics of the virome may hold important keys to human health. BMC Biol 2014 Sep 10; 12(1):71

Pan-genome and comparative genome analyses of Propionibacterium acnes reveal its genomic diversity in the healthy and diseased human skin microbiome

Propionibacterium acnes constitutes a major part of the skin microbiome and contributes to human health. However, it has also been implicated as a pathogenic factor in several diseases, including acne, one of the most common skin diseases. Its pathogenic role, however, remains elusive. To better understand the genetic landscape and diversity of the organism and its role in human health and disease, we performed a comparative genome analysis of 82 P. acnes strains, 69 of which were sequenced by our group. This collection covers all known P. acnes lineages, including types IA, IB, II, and III. Our analysis demonstrated that although the P. acnes pan-genome is open, it is relatively small and expands slowly. The core regions, shared by all the sequenced genomes, accounted for 88% of the average genome. Comparative genome analysis showed that within each lineage, the strains isolated from the same individuals were more closely related than the ones isolated from different individuals, suggesting that clonal expansions occurred within each individual microbiome. We also identified the genetic elements specific to each lineage. Differences in harboring these elements may explain the phenotypic and functional differences of P. acnes in functioning as a commensal in healthy skin and as a pathogen in diseases. Our findings of the differences among P. acnes strains at the genome level underscore the importance of identifying the human microbiome variations at the strain level in understanding its association with diseases and provide insight into novel and personalized therapeutic approaches for P. acnes-related diseases