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SUMMARYLoss of antimicrobial proteins such as REG3 family members compromises the integrity of the intestinal barrier. Here, we demonstrate that overproduction of REG3 proteins can also be detrimental by reducing a protective species in the microbiota. Patients with inflammatory bowel disease (IBD) experiencing flares displayed heightened levels of secreted REG3 proteins that mediated depletion ofEnterococcus faecium(Efm) from the gut microbiota.Efminoculation of mice ameliorated intestinal inflammation through activation of the innate immune receptor NOD2, which was associated with the bacterial DL-endopeptidase SagA. Microbiota sensing by NOD2 in myeloid cells mediated IL-1β secretion and increased the proportion of IL-22-producing CD4+T helper cells and innate lymphoid cells. Finally,Efmwas unable to protect mice carrying aNOD2gene variant commonly found in IBD patients. Our findings demonstrate that inflammation self-perpetuates by causing aberrant antimicrobial activity that disrupts symbiotic relationships with gut microbes.

A goal in precision medicine is to use patient-derived material to predict disease course and intervention outcomes. Here, we use mechanistic observations in a preclinical animal model to design an ex vivo platform that recreates genetic susceptibility to T-cell–mediated damage. Intestinal graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation. We found that intestinal GVHD in mice deficient in Atg16L1, an autophagy gene that is polymorphic in humans, is reversed by inhibiting necroptosis. We further show that cocultured allogeneic T cells kill Atg16L1-mutant intestinal organoids from mice, which was associated with an aberrant epithelial interferon signature. Using this information, we demonstrate that pharmacologically inhibiting necroptosis or interferon signaling protects human organoids derived from individuals harboring a common ATG16L1 variant from allogeneic T-cell attack. Our study provides a roadmap for applying findings in animal models to individualized therapy that targets affected tissues.

SUMMARYContributions of the viral component of the microbiome, the virome, to the development of innate and adaptive immunity are largely unknown. Here, we systematically defined the host response in mice to a panel of eukaryotic enteric viruses representing six different families. Most of these viruses asymptomatically infected the mice, the magnitude and duration of which was dependent on the microbiota. Flow cytometric and transcriptional profiling of mice mono-associated with these viruses unveiled general adaptations by the host, such as lymphocyte differentiation and IL-22 signatures in the intestine as well as numerous viral strain-specific responses that persist. Comparison with a dataset derived from analogous bacterial mono-association mice identified bacterial species that evoke an immune response comparable to the viruses we examined. These results expand an understanding of the immune space occupied by the enteric virome and underscore the importance of viral exposure events.

The contributions of the viral component of the microbiome-the virome-to the development of innate and adaptive immunity are largely unknown. Here, we systematically defined the host response in mice to a panel of eukaryotic enteric viruses representing six different families. Infections with most of these viruses were asymptomatic in the mice, the magnitude and duration of which was dependent on the microbiota. Flow cytometric and transcriptional profiling of mice mono-associated with these viruses unveiled general adaptations by the host, such as lymphocyte differentiation and IL-22 signatures in the intestine, as well as numerous viral-strain-specific responses that persisted. Comparison with a dataset derived from analogous bacterial mono-association in mice identified bacterial species that evoke an immune response comparable with the viruses we examined. These results expand an understanding of the immune space occupied by the enteric virome and underscore the importance of viral exposure events.

The enteric virome includes viruses that infect eukaryotic cells in the gut and is one constituent of the mammalian microbiome. Although best known for causing acute diarrheal disease, many of these viruses cause subclinical infections, and indeed are often detected in asymptomatic individuals. The consequences of harboring these viruses are unclear. We recently demonstrated that norovirus mono-colonization promotes the development of the intestinal architecture and the mucosal immune system of germ-free mice in a manner similar to symbiotic bacteria and can protect against models of chemical and microbial injury. It is unclear whether this symbiotic virus-host relationship is a unique feature of murine norovirus strain CR6 colonization. Here, we examined the extent to which members of the eukaryotic enteric virome contribute to the state of the host health. Examination of 10 enteric DNA and RNA viruses representing 6 viral families capable of spreading through the fecal-oral route revealed that many establish a prolonged infection, which often is not limited to the intestinal tissues, in the absence of visible disease after oral inoculation. Further histologic analysis of the small intestinal and colonic tissues confirmed no pathogenic effects on the intestinal tissues. To evaluate the direct impact of asymptomatic viral infections independently from the bacterial microbiome, we performed RNA-seq on intestinal tissues and a comprehensive flow cytometry analysis of intestinal and extraintestinal organs, assessing over 20 immune cell subsets and their cytokine production capacity, following viral mono-colonization of germ-free mice. We found profound effects exerted by the enteric viruses on the immune system in all the tissues tested. In addition to confirming anticipated consequences of viral infection such as expansions of Th1 cells and effector memory T cells, we identified novel virus-specific responses, such as norovirus-induced expansion of type 1 regulatory T cells and parvovirus-mediated induction of regulatory T cells. Interestingly, intestinal T cells and innate lymphoid cells from almost all the virome-colonized mice were more predisposed towards the production of proinflammatory Th1 cytokines, such as IFNγ, and of Il22. An increase in the IL22 signature was also detected in the intestinal transcriptome of virome-colonized mice, suggesting that the virome members support the production of this cytokine already at the steady-state level. Of note, only a few viruses were inducing a type I interferon signature in the tissues, suggesting that pathways other than type I interferon mediate the virome effects on the host. Taken together, these data demonstrate that multiple members of the enteric virome can contribute to the development and function of the mucosal immune system. This abstract is also being presented as Poster A13. Citation Format: Simone Dallari, Thomas Heaney, Adriana Rosas-Villegas, Ken Cadwell. Functional characterization of the enteric animal virome as mediator of host health [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr PR03.

The enteric virome includes viruses that infect eukaryotic cells in the gut and is one constituent of the mammalian microbiome. Although best known for causing acute diarrheal disease, many of these viruses are detected in asymptomatic individuals. The immune consequence of harboring these viruses is unclear. We recently demonstrated that norovirus infection promotes the development of the mucosal immune system in mice in a manner similar to symbiotic bacteria, and can protect against models of chemical and microbial injury. These results are reminiscent of findings from the microbiome field demonstrating that intestinal colonization by individual bacterial species directs the differentiation of the immune system. Here, we examined the extent to which the eukaryotic enteric virome contributes to the state of the host immune system. Examination of 10 enteric DNA and RNA viruses, representing 6 viral families, revealed that many establish prolonged infection in the absence of disease. To evaluate the immunological impact of these viral infections that occurs independently of other members of the microbiome, we performed a comprehensive flow cytometry analysis of several organs following infection of germ-free mice that assessed over 20 immune cell subsets and their capacity for cytokine production. We found profound effects of enteric viral infection in all the tissues tested, showing strain-specific responses, such as norovirus-induced expansion of type 1 regulatory T cells, and commonly shared ones, such as the increased potential of colonic T cells to produce Il-22. Taken together, these data demonstrate that enteric virome members contribute to the immune status of the host.

This research builds on a connection between adult education and democracy by exploring best practices in shared governance in a major venue of adult education—the academy. Its purpose is to enhance democratic practices within the university and encourage the creation of new structures for shared decision making.

In this chapter, three graduates and a faculty member analyze efforts to create a democratic practice in the context of their doctoral program in adult education.