Recognition of DNA by the cell is an important immunological signature that marks the initiation of an innate immune response. AIM2 is a cytoplasmic sensor that recognizes dsDNA of microbial or host ...origin. Upon binding to DNA, AIM2 assembles a multiprotein complex called the inflammasome, which drives pyroptosis and proteolytic cleavage of the proinflammatory cytokines pro‐IL‐1β and pro‐IL‐18. Release of microbial DNA into the cytoplasm during infection by Francisella, Listeria, Mycobacterium, mouse cytomegalovirus, vaccinia virus, Aspergillus, and Plasmodium species leads to activation of the AIM2 inflammasome. In contrast, inappropriate recognition of cytoplasmic self‐DNA by AIM2 contributes to the development of psoriasis, dermatitis, arthritis, and other autoimmune and inflammatory diseases. Inflammasome‐independent functions of AIM2 have also been described, including the regulation of the intestinal stem cell proliferation and the gut microbiota ecology in the control of colorectal cancer. In this review we provide an overview of the latest research on AIM2 inflammasome and its role in infection, cancer, and autoimmunity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Inflammatory caspases drive a lytic form of cell death called pyropto- sis in response to microbial infection and endogenous damage-associated signals. Two studies now demonstrate that cleavage of ...the substrate gas- dermin D by inflammatory caspases necessitates eventual pyroptotic demise of a cell.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Inflammation underpins and contributes to the pathogenesis of many retinal degenerative diseases. The recruitment and activation of both resident microglia and recruited macrophages, as well as the ...production of cytokines, are key contributing factors for progressive cell death in these diseases. In particular, the interleukin 1 (IL-1) family consisting of both pro- and anti-inflammatory cytokines has been shown to be pivotal in the mediation of innate immunity and contribute directly to a number of retinal degenerations, including Age-Related Macular Degeneration (AMD), diabetic retinopathy, retinitis pigmentosa, glaucoma, and retinopathy of prematurity (ROP). In this review, we will discuss the role of IL-1 family members and inflammasome signaling in retinal degenerative diseases, piecing together their contribution to retinal disease pathology, and identifying areas of research expansion required to further elucidate their function in the retina.
The enrichment of Gram-negative bacteria of oral origin in the esophageal microbiome has been associated with the development of metaplasia. However, to date, no study has comprehensively assessed ...the relationships between the esophageal microbiome and the host.
Here, we examine the esophageal microenvironment in gastro-esophageal reflux disease and metaplasia using multi-omics strategies targeting the microbiome and host transcriptome, followed by targeted culture, comparative genomics, and host-microbial interaction studies of bacterial signatures of interest.
Profiling of the host transcriptome from esophageal mucosal biopsies revealed profound changes during metaplasia. Importantly, five biomarkers showed consistent longitudinal changes with disease progression from reflux disease to metaplasia. We showed for the first time that the esophageal microbiome is distinct from the salivary microbiome and the enrichment of Campylobacter species as a consistent signature in disease across two independent cohorts. Shape fitting and matrix correlation identified associations between the microbiome and host transcriptome profiles, with a novel co-exclusion relationship found between Campylobacter and napsin B aspartic peptidase. Targeted culture of Campylobacter species from the same cohort revealed a subset of isolates to have a higher capacity to survive within primary human macrophages. Comparative genomic analyses showed these isolates could be differentiated by specific genomic features, one of which was validated to be associated with intracellular fitness. Screening for these Campylobacter strain-specific signatures in shotgun metagenomics data from another cohort showed an increase in prevalence with disease progression. Comparative transcriptomic analyses of primary esophageal epithelial cells exposed to the Campylobacter isolates revealed expression changes within those infected with strains with high intracellular fitness that could explain the increased likelihood of disease progression.
We provide a comprehensive assessment of the esophageal microenvironment, identifying bacterial strain-specific signatures with high relevance to progression of metaplasia.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The presence of Campylobacter species other than Campylobacter jejuni and antibodies to Campylobacter concisus in children were investigated. A significantly greater presence of C. concisus and ...higher levels of antibodies to C. concisus were detected in children with Crohn's disease (CD) than in controls. Campylobacter species other than C. jejuni were isolated from intestinal biopsy specimens of children with CD.
Guanylate‐binding proteins (GBPs) are a group interferon‐inducible GTPases within the constellation of the dynamin GTPase superfamily. These proteins restrict the replication of intracellular ...pathogens in both immune and non‐immune cells. GBPs and their related family members immunity‐related GTPases target and lyse the membrane of the pathogen‐containing vacuole, destroying the residential niche of vacuolar protozoal and bacterial pathogens. They also prevent virion infectivity and target replication complexes of ribonucleic acid viruses. The exciting concept that GBPs and immunity‐related GTPases can directly target the membrane of bacteria and protozoa has emerged. Rupture and lysis of the pathogen membrane mediates liberation of concealed microbial ligands for activation of innate immune sensing pathways and the inflammasome. Further studies have demonstrated a capacity of GBPs to recruit additional antimicrobial factors, highlighting the complexity of the molecular mechanisms involved in pathogen killing. In this mini‐review, we discuss recent advances describing the localisation and functions of GBPs on the host and pathogen membrane. We also highlight unresolved questions related to the regulation of GBPs in cell‐autonomous immunity to intracellular pathogens.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Inflammasomes are critical for mounting host defense against pathogens. The molecular mechanisms that control activation of the AIM2 inflammasome in response to different cytosolic pathogens remain ...unclear. Here we found that the transcription factor IRF1 was required for activation of the AIM2 inflammasome during infection with the Francisella tularensis subspecies novicida (F. novicida), whereas engagement of the AIM2 inflammasome by mouse cytomegalovirus (MCMV) or transfected double-stranded DNA did not require IRF1. Infection of F. novicida detected by the DNA sensor cGAS and its adaptor STING induced type I interferon-dependent expression of IRF1, which drove the expression of guanylate-binding proteins (GBPs); this led to intracellular killing of bacteria and DNA release. Our results reveal a specific requirement for IRF1 and GBPs in the liberation of DNA for sensing by AIM2 depending on the pathogen encountered by the cell.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Background. Campylobacter concisus and other non-Campylobacter jejuni Campylobacter species have been implicated in the initiation of gastrointestinal diseases. In the present study, we investigated ...the interaction between these bacteria and the human intestinal epithelium and immune cells. Methods. The ability of C. concisus, Campylobacter showae, Campylobacter hominis, and Bacteroides ureolyticus to invade epithelial cells was examined using scanning electron microscopy and gentamicin protection assays. Proinflammatory cytokines generated by epithelial and immune cells in response to these bacteria were determined by enzyme-linked immunosorbent assay. Ussing Chamber, immunofluorescent stain, and Western blot were used to further elucidate the impact of C. concisus on intestinal barrier integrity and functions. Results. Attachment of non-C. jejuni Campylobacter species to Caco-2 or HT-29 cells was mediated by flagellum- dependent and/or -independent processes. C. concisus was able to invade Caco-2 cells, generate a membraneruffling effect on the epithelial surface on entry, and damage epithelial barrier functions by preferential attachment to the cell-cell junctions. Proinflammatory cytokine profiles exhibited by epithelial cells, monocytes, and macrophages in response to C. concisus and other non-C. jejuni Campylobacter species were species and strain specific. Conclusions. These findings demonstrate that C. concisus and other non-C. jejuni Campylobacter species may play a role in initiating gastrointestinal diseases.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
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