Genome-wide association study implicates immune activation of multiple integrin genes in inflammatory bowel disease

Genetic association studies have identified 215 risk loci for inflammatory bowel disease, thereby uncovering fundamental aspects of its molecular biology. We performed a genome-wide association study of 25,305 individuals and conducted a meta-analysis with published summary statistics, yielding a total sample size of 59,957 subjects. We identified 25 new susceptibility loci, 3 of which contain integrin genes that encode proteins in pathways that have been identified as important therapeutic targets in inflammatory bowel disease. The associated variants are correlated with expression changes in response to immune stimulus at two of these genes ($\textit{ITGA4 }$ and $\textit{ITGB8}$) and at previously implicated loci ($\textit{ITGAL }$and $\textit{ICAM1}$). In all four cases, the expression-increasing allele also increases disease risk. We also identified likely causal missense variants in a gene implicated in primary immune deficiency, $\textit{PLCG2}$, and a negative regulator of inflammation, $\textit{SLAMF8}$. Our results demonstrate that new associations at common variants continue to identify genes relevant to therapeutic target identification and prioritization.This work was co-funded by the Wellcome Trust [098051] and the Medical Research Council, UK [MR/J00314X/1]. Case collections were supported by Crohn’s and Colitis UK. KMdL, LM, CAL, YL, DR, JG-A, NJP, CAA and JCB are supported by the Wellcome Trust [098051; 093885/Z/10/Z; 094491/Z/10/Z]. KMdL is supported by a Woolf Fisher Trust scholarship. CAL is a clinical lecturer funded by the NIHR. We thank Anna Stanton for co-ordinating the Guy’s and St Thomas’ patient recruitment. We acknowledge support from the Department of Health via the NIHR comprehensive Biomedical Research Centre awards to Guy’s and St Thomas’ NHS Foundation Trust in partnership with King’s College London and to Addenbrooke’s Hospital, Cambridge in partnership with the University of Cambridge. This research was also supported by the NIHR Newcastle Biomedical Research Centre. The UK Household Longitudinal Study is led by the Institute for Social and Economic Research at the University of Essex and funded by the Economic and Social Research Council

The Metagenome of an Anaerobic Microbial Community Decomposing Poplar Wood Chips

This study describes the composition and metabolic potential of a lignocellulosic biomass degrading community that decays poplar wood chips under anaerobic conditions. We examined the community that developed on poplar biomass in a non-aerated bioreactor over the course of a year, with no microbial inoculation other than the naturally occurring organisms on the woody material. The composition of this community contrasts in important ways with biomass-degrading communities associated with higher organisms, which have evolved over millions of years into a symbiotic relationship. Both mammalian and insect hosts provide partial size reduction, chemical treatments (low or high pH environments), and complex enzymatic ‘secretomes’ that improve microbial access to cell wall polymers. We hypothesized that in order to efficiently degrade coarse untreated biomass, a spontaneously assembled free-living community must both employ alternative strategies, such as enzymatic lignin depolymerization, for accessing hemicellulose and cellulose and have a much broader metabolic potential than host-associated communities. This would suggest that such a community would make a valuable resource for finding new catalytic functions involved in biomass decomposition and gaining new insight into the poorly understood process of anaerobic lignin depolymerization. Therefore, in addition to determining the major players in this community, our work specifically aimed at identifying functions potentially involved in the depolymerization of cellulose, hemicelluloses, and lignin, and to assign specific roles to the prevalent community members in the collaborative process of biomass decomposition. A bacterium similar to Magnetospirillum was identified among the dominant community members, which could play a key role in the anaerobic breakdown of aromatic compounds. We suggest that these compounds are released from the lignin fraction in poplar hardwood during the decay process, which would point to lignin-modification or depolymerization under anaerobic conditions

Self-Mating in the Definitive Host Potentiates Clonal Outbreaks of the Apicomplexan Parasites Sarcocystis neurona and Toxoplasma gondii

Tissue-encysting coccidia, including Toxoplasma gondii and Sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. During its sexual life stage, T. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. Out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. In contrast, selfing and other life history traits, such as asexual expansion of tissue-cysts by oral transmission among intermediate hosts, have been proposed to explain the genetic basis for the clonal population structure of T. gondii. In this study, we investigated the contributing roles self-mating and sexual recombination play in nature to maintain clonal population structures and produce or expand parasite clones capable of causing disease epidemics for two tissue encysting parasites. We applied high-resolution genotyping against strains isolated from a T. gondii waterborne outbreak that caused symptomatic disease in 155 immune-competent people in Brazil and a S. neurona outbreak that resulted in a mass mortality event in Southern sea otters. In both cases, a single, genetically distinct clone was found infecting outbreak-exposed individuals. Furthermore, the T. gondii outbreak clone was one of several apparently recombinant progeny recovered from the local environment. Since oocysts or sporocysts were the infectious form implicated in each outbreak, the expansion of the epidemic clone can be explained by self-mating. The results also show that out-crossing preceded selfing to produce the virulent T. gondii clone. For the tissue encysting coccidia, self-mating exists as a key adaptation potentiating the epidemic expansion and transmission of newly emerged parasite clones that can profoundly shape parasite population genetic structures or cause devastating disease outbreaks

The Fecal Viral Flora of Wild Rodents

The frequent interactions of rodents with humans make them a common source of zoonotic infections. To obtain an initial unbiased measure of the viral diversity in the enteric tract of wild rodents we sequenced partially purified, randomly amplified viral RNA and DNA in the feces of 105 wild rodents (mouse, vole, and rat) collected in California and Virginia. We identified in decreasing frequency sequences related to the mammalian viruses families Circoviridae, Picobirnaviridae, Picornaviridae, Astroviridae, Parvoviridae, Papillomaviridae, Adenoviridae, and Coronaviridae. Seventeen small circular DNA genomes containing one or two replicase genes distantly related to the Circoviridae representing several potentially new viral families were characterized. In the Picornaviridae family two new candidate genera as well as a close genetic relative of the human pathogen Aichi virus were characterized. Fragments of the first mouse sapelovirus and picobirnaviruses were identified and the first murine astrovirus genome was characterized. A mouse papillomavirus genome and fragments of a novel adenovirus and adenovirus-associated virus were also sequenced. The next largest fraction of the rodent fecal virome was related to insect viruses of the Densoviridae, Iridoviridae, Polydnaviridae, Dicistroviriade, Bromoviridae, and Virgaviridae families followed by plant virus-related sequences in the Nanoviridae, Geminiviridae, Phycodnaviridae, Secoviridae, Partitiviridae, Tymoviridae, Alphaflexiviridae, and Tombusviridae families reflecting the largely insect and plant rodent diet. Phylogenetic analyses of full and partial viral genomes therefore revealed many previously unreported viral species, genera, and families. The close genetic similarities noted between some rodent and human viruses might reflect past zoonoses. This study increases our understanding of the viral diversity in wild rodents and highlights the large number of still uncharacterized viruses in mammals

Ageism and Dementia

This chapter explores the relationship between ageism and dementia. Although dementia is not an unavoidable consequence of ageing, increasing age is the biggest risk factor for having this disease. The prevalence of dementia increases exponentially with age and 95% of those with Alzheimer's Disease, the most common form of dementia, are aged 65 or over. Dementia often has strong negative connotations, partly driven by alarmist media portrayals of the disease, which means that people living with the condition can experience the `double stigma' of ageism and dementia-related discrimination. The stigma attached to dementia can have significant implications for quality of life through, for example, decreased social engagement, reduced self-esteem, increased carer burden and sub-standard healthcare, a situation that is exacerbated by low levels of diagnosis and inadequate training of medical professionals. Despite attempts by governments and not for profit organisations to tackle dementia-related stigma, there remains a strong need to raise awareness of the realities of living with dementia and to reduce the impact of discrimination. This chapter explores the inter-connections and overlaps between ageing and discrimination because someone has dementia. The relationship between dementia and age is discussed, followed by an exploration of the impacts of dementia-related stigma for the individual and society. The chapter continues by analysing the role of the media in fuelling stigma and how having dementia can impact on the receipt of health and social care services. The chapter explores the implications of dementia stigma for social engagement and ends by considering how perceptions of dementia are reflected in research funding