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- Chassaing, Benoit, et al.
(författare)
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Crohn disease-associated adherent-invasive E. coli bacteria target mouse and human Peyers patches via long polar fimbriae
- 2011
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Ingår i: JOURNAL OF CLINICAL INVESTIGATION. - : American Society for Clinical Investigation. - 0021-9738. ; 121:3, s. 966-975
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Tidskriftsartikel (refereegranskat)abstract
- Crohn disease (CD) is a multifactorial disease in which an abnormal immune response in the gastrointestinal (GI) tract leads to chronic inflammation. The small intestine, particularly the ileum, of patients with CD is colonized by adherent-invasive E. coil (AIEC) a pathogenic group of E. coil able to adhere to and invade intestinal epithelial cells. As the earliest inflammatory lesions are microscopic erosions of the epithelium lining the Peyers patches (PPs), we investigated the ability of AIEC bacteria to interact with PPs and the virulence factors involved. We found that AIEC bacteria could interact with mouse and human PPs via long polar fimbriae (LPF). An LPF-negative AIEC mutant was highly impaired in its ability to interact with mouse and human PPs and to translocate across monolayers of M cells, specialized epithelial cells at the surface of PPs. The prevalence of AIEC strains harboring the lpf operon was markedly higher in CD patients compared with controls. In addition, increased numbers of AIEC, but not LPF-deficient AIEC, bacteria were found interacting with PPs from Nod2(-/-) mice compared with WT mice. In conclusion, we have identified LPF as a key factor for AIEC to target PPs. This could be the missing link between AIEC colonization and the presence of early lesions in the PPs of CD patients.
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| 2. |
- Keita, Åsa, et al.
(författare)
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Enhanced E. coli LF82 Translocation through the Follicle-associated Epithelium in Crohns Disease is Dependent on Long Polar Fimbriae and CEACAM6 expression, and Increases Paracellular Permeability
- 2020
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Ingår i: Journal of Crohn's & Colitis. - : OXFORD UNIV PRESS. - 1873-9946 .- 1876-4479. ; 14:2, s. 216-229
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: Patients with Crohns disease [CD] harbour an increased number of adherent-invasive E. coli [AIEC]. The strain LF82, identified in the ileal mucosa of CD patients, has been extensively studied for pathogenic mechanisms. However, understanding of the interaction of LF82 with the intestinal mucosa of CD patients is lacking. Methods: Here, we investigated the importance of long polar fimbriae [LPF] type 1 pili and the carcinoembryonic antigen-related cell-adhesion molecule 6 [CEACAM6] for translocation of LF82 in an in vitro model of follicle-associated epithelium [FAE], and in the FAE and villus epithelium [VE] of patients with CD and controls, using Ussing chambers. Results: Significantly greater LF82 passage occurred in the FAE model compared with in the VE Caco-2cl1 mono-culture. Moreover, bacterial translocation was inhibited by either LPF disruption or pre-incubation with anti-CEACAM6 antibody. Tissue mounted in Ussing chambers showed significantly higher LF82 passage in FAE from patients with CD compared with control FAE, that was diminished in LF82 lacking LPF and by blocking host CEACAM6. Interestingly, addition of LF82 to the CD FAE tissues significantly increased paracellular permeability [of (51)Chromium-EDTA] compared with baseline, and the increase was inhibited by anti-CEACAM6. Immunofluorescence and immunoblots showed higher expression of CEACAM6 in FAE of patients with CD compared with in FAE from controls. Conclusions: These data suggest that the FAE of CD patients is a site of vulnerability for invasion by LF82 via a mechanism that requires both bacterial LPF and host CEACAM6. Further, LF82 has the ability to increase paracellular passage through the FAE of patients with CD. These data can help define novel therapeutic targets in CD for the prevention of clinical recurrence.
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| 3. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 5. |
- Salim, Sa'ad Yislam, 1977-, et al.
(författare)
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Barrier defect in the follicle-associated epithelium of SAMP1/YitFc mice demonstrates vulnerability to adherent-invasive Escherichia coli LF82
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- SAMP1/YitFc mice are a unique murine model for Crohn’s disease (CD) as they develop spontaneous intestinal inflammation without chemical or genetic manipulations. Inflammation is primarily located in the distal ileum, which is the hallmark location for CD. It is at the distal ileum of CD where small erosions that develop at the follicle-associated epithelium (FAE) and are one of the earliest observable lesions in recurrent ileitis. In the report, we studied the intestinal permeability defect and examined the role of dendritic cells (DCs) in the SAMP1/YitFc mice ileitis. Segments of FAE and VE from 11 and 27 weeks old SAMP1/YitFc mice and AKR control background stains were mounted on Ussing chambers. Electrical conductivity and permeability to 51Cr-EDTA, horseradish peroxidise (HRP) and E.coli HB101 and LF82 were recorded. There was ileal permeability to 51Cr-EDTA and HRP in the 27 weeks old SAMP1/YitFc mice. Both E.coli HB101 and LF82 increased conductance by two-folds in FAE and VE of SAMP1/YitFc mice. Furthermore, both bacterial strains increased tissue conductance and 51Cr-EDTA passage. There was greater passage of E.coli LF82 in the 27 week old DAMP1/YitFc mice than in controls. Confocal microscopy revealed a high number of CD11c+ DCs in the sub-epithelial dome (SED) area, though there was no difference between the SAMP1/YitFc mice than the AKR controls. Immunofluorescence characterisation also did not reveal any phenotypic difference in DCs between the mice strains. These results show that SAMP1/YitFc mice have a barrier defect, which was more pronounced in the FAE of older mice, and demonstrate a mucosal sensitivity bacteria. It also confirms that this model of chronic ileitis is primarily a defect in permeability defect and not DCs.
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