| 1. |
- Agace, William
(författare)
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The role of the epithelial cell in Escherichia coli induced neutrophil migration into the urinary tract.
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study examined the molecular mechanisms of neutrophil migration to sites of mucosal bacterial infection. (1) Bacterial induction of neutrophil chemotactic cytokines and their role in neutrophil migration. Uropathogenic E.coli were shown to stimulate urinary tract epithelial cells to produce a specific array of cytokines including the neutrophil chemoattractant IL-8. IL-8 production was dependent on the adherence properties of the infecting strain. Deliberate colonisation of the human urinary tract with E.coli induced the local production of IL-8 and levels correlated with urinary neutrophil numbers. The E.coli induced IL-8 supported neutrophil migration across urinary tract epithelial layers in vitro and anti-IL-8 antibody blocked this response. The chemotactically active IL-8 was localised to the epithelial surface and these cells contained IL-8 receptor A and B mRNA. (2) The role of epithelial adhesion molecules in E.coli induced transuroepithelial migration. Uroepithelial cells constitutively expressed ICAM-1 and E.coli augmented ICAM-1 expression. Transuroepithelial neutrophil migration was dependent on epithelial ICAM-1 and neutrophil Mac-1 (CD11b/CD18) expression. Thus urinary tract epithelial cells provide two prerequisites for neutrophil migration to the mucosal lumen; neutrophil chemoattractants and cell adhesion molecules. (3) The role of bacterial fimbriae for the induction of inflammation in the urinary tract. Patients and mice infected with a type 1 positive P fimbriated uropathogenic E.coli clone O1:K1:H7 showed significantly higher inflammatory responses than type 1 negative O1:K1:H7 isolates. Insertion of an npt gene into fimH (encoding the type 1 fimbrial adhesin) of a type 1 positive O1:K1:H7 isolate resulted in the loss of the type 1 fimbrial phenotype and a reduction in virulence.
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| 2. |
- Benson, Mikael, et al.
(författare)
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Interleukin (IL)-6 and IL-8 in children with febrile urinary tract infection and asymptomatic bacteriuria
- 1996
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 174:5, s. 1080-1084
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Tidskriftsartikel (refereegranskat)abstract
- Urine and serum interleukin (IL)-6 and IL-8 responses were higher in children with febrile urinary tract infection (n = 61) than in those with asymptomatic bacteriuria (n = 39). By univariate analysis, cytokine levels were related to age, sex, reflux, renal scarring, urine leukocytes, C- reactive protein (CRP), erythrocyte sedimentation rate (ESR), and bacterial properties (P fimbriae but not hemolysin). Multivariate modeling showed that urine IL-6 responds were higher in girls than boys, increased with age, and were positively associated with CRP, ESR, serum IL-6, and urine leukocyte counts. The urine IL-8 response was not influenced by age, but it was influenced by P fimbriae and was associated with ESR, CRP, urine leukocytes, and female sex. The results show that cytokine responses to urinary tract infection vary with the severity of infection and that cytokine activation is influenced by a variety of host and bacterial variables.
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| 3. |
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| 4. |
- Godaly, Gabriela, et al.
(författare)
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Role of epithelial interleukin-8 (IL-8) and neutrophil IL-8 receptor A in Escherichia coli-induced transuroepithelial neutrophil migration
- 1997
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Ingår i: Infection and Immunity. - 1098-5522. ; 65:8, s. 3451-3456
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Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli stimulates neutrophil migration across human uroepithelial cell layers. This study investigated the role of the neutrophil chemokine interleukin-8 (IL-8) in this process. E. coli and IL-1alpha stimulated urinary tract epithelial layers to secrete IL-8 and induced transepithelial neutrophil migration. Anti-IL-8 antibody reduced neutrophil migration across epithelial cell layers, indicating a central role for this chemokine in the migration process. Furthermore, addition of recombinant IL-8 to unstimulated cell layers was sufficient to induce migration. The IL-8 dependence of neutrophil migration was maintained after removal of soluble IL-8 by washing of the cell layers. Flow cytometry analysis with fluorescein isothiocyanate-labelled IL-8 confirmed IL-8's ability to bind to the epithelial cell surface. Indirect immunofluorescence with confocal laser scanning microscopy showed that IL-8 associated with the epithelial cell layers. Prior incubation of neutrophils with antibodies to IL-8 receptor A (IL-8RA) reduced neutrophil migration. Anti-IL-8 RB antibody had no effect on neutrophil migration. These results demonstrate that IL-8 plays a key role in E. coli- or IL-1alpha-induced transuroepithelial migration and suggest that epithelial cell-produced IL-8 interacts with IL-8RA on the neutrophil surface.
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| 5. |
- Hang, Long, et al.
(författare)
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Macrophage inflammatory protein-2 is required for neutrophil passage across the epithelial barrier of the infected urinary tract
- 1999
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Ingår i: Journal of Immunology. - 1550-6606. ; 162:5, s. 3037-3044
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Tidskriftsartikel (refereegranskat)abstract
- IL-8 is a major human neutrophil chemoattractant at mucosal infection sites. This study examined the C-X-C chemokine response to mucosal infection, and, specifically, the role of macrophage inflammatory protein (MIP)-2, one of the mouse IL-8 equivalents, for neutrophil-epithelial interactions. Following intravesical Escherichia coli infection, several C-X-C chemokines were secreted into the urine, but only MIP-2 concentrations correlated to neutrophil numbers. Tissue quantitation demonstrated that kidney MIP-2 production was triggered by infection, and immunohistochemistry identified the kidney epithelium as a main source of MIP-2. Treatment with anti-MIP-2 Ab reduced the urine neutrophil numbers, but the mice had normal tissue neutrophil levels. By immunohistochemistry, the neutrophils were found in aggregates under the pelvic epithelium, but in control mice the neutrophils crossed the urothelium into the urine. The results demonstrate that different chemokines direct neutrophil migration from the bloodstream to the lamina propria and across the epithelium and that MIP-2 serves the latter function. These findings suggest that neutrophils cross epithelial cell barriers in a highly regulated manner in response to chemokines elaborated at this site. This is yet another mechanism that defines the mucosal compartment and differentiates the local from the systemic host response.
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| 6. |
- Hedges, Spencer R., et al.
(författare)
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Epithelial cytokine responses and mucosal cytokine networks
- 1995
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Ingår i: Trends in Microbiology. - 0966-842X. ; 3:7, s. 266-270
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Forskningsöversikt (refereegranskat)abstract
- Localized at the border between the external environment and the internal tissue, epithelial cells are exposed to stimulants from two directions. Microorganisms in the lumen can activate the transcription of cytokine mRNA and cytokine secretion, and cytokines in the mucosal environment can modify endogenous and microbially induced epithelial cytokine responses. Epithelial cells thus actively participate in mucosal immunity and inflammation.
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| 7. |
- Hedges, Spencer R., et al.
(författare)
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Immunoregulatory cytokines modify Escherichia coli induced uroepithelial cell IL-6 and IL-8 responses
- 1996
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Ingår i: Cytokine. - : Elsevier BV. - 1043-4666. ; 8:9, s. 686-697
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Tidskriftsartikel (refereegranskat)abstract
- This study analysed the effects of immunoregulatory cytokines on uroepithelial cell cytokine responses. The A-498 human kidney cell line was treated with the interleukins IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, interferon gamma (IFN-α) and transforming growth factor beta (TGF-β1). Secreted IL-6 and IL-8 were quantitated by enzyme-linked immunoabsorbent assay (ELISA) and bioassay; IL-6 and IL-8 mRNA species were quantitated by reverse transcriptase polymerase chain reaction (RT-PCR). IL-4, IL-13, IFN-γ, and TGF-β1, but not IL-2, IL-5, IL-10 or IL-12, stimulated IL-6 secretion. At high concentrations, IL-4 and IL-13 stimulated low levels of IL-8 secretion. Immunoregulatory cytokines were analysed for their ability to modify the A-498 cells' IL-6 and IL-8 secretion in response to Escherichia coli. IL-5, IL-12, IL-13 and TGF-β1 additively enhanced the bacterially induced IL-6 secretion, but they did not affect IL-8 secretion. The strongest affects on uroepithelial cell IL-6 and IL-8 responses in the presence of bacteria were observed in conjunction with IL-4 and IFN-α. IL-4 induced IL-6 production in synergy with E. coli. IFN-α both enhanced and inhibited IL-6 and IL-8 responses in combination with E. coli, depending on the order of stimulant addition. The results demonstrate that immunoregulatory cytokines can modify the uroepithelial cell responses to bacteria in vitro. In this way T cells may regulate the cytokine responses of uroepithelial and possibly other mucosal epithelial cells in vivo.
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| 8. |
- Leffler, Hakon, et al.
(författare)
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Strategies for studying bacterial adhesion in Vivo
- 1995. - C
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Ingår i: Adhesion of Microbial Pathogens. - 0076-6879. ; 253, s. 206-220
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Bokkapitel (refereegranskat)abstract
- The ultimate goal of studies on microbial adhesion is to understand what molecular interactions between the host and microbe occur in vivo and the impact of these interactions on disease processes. With this goal in mind, the problem can be approached at four levels. At the biochemical level, the host receptors at the relevant colonization site are identified; at the cell biology level, consequences of bacterial binding to host epithelial cells are studied in cell culture; at the physiological level, the consequences of bacterial binding are studied in experimental animals or humans; and at the population level, the consequences of receptor binding for colonization are studied by epidemiological methods. This chapter provides an example of studies at each level and discusses the implications for what might occur in vivo.
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| 9. |
- Schon, M P, et al.
(författare)
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Mucosal T lymphocyte numbers are selectively reduced in integrin alpha E (CD103)-deficient mice
- 1999
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Ingår i: Journal of Immunology. - 1550-6606. ; 162:11, s. 6641-6649
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Tidskriftsartikel (refereegranskat)abstract
- The mucosal lymphocyte integrin alpha E(CD103)beta 7 is thought to be important for intraepithelial lymphocyte (IEL) localization or function. We cloned the murine integrin gene encoding alpha E, localized it to chromosome 11, and generated integrin alpha E-deficient mice. In alpha E-/- mice, intestinal and vaginal IEL numbers were reduced, consistent with the known binding of alpha E beta 7 to E-cadherin expressed on epithelial cells. However, it was surprising that lamina propria T lymphocyte numbers were diminished, as E-cadherin is not expressed in the lamina propria. In contrast, peribronchial, intrapulmonary, Peyer's patch, and splenic T lymphocyte numbers were not reduced in alpha E-deficient mice. Thus, alpha E beta 7 was important for generating or maintaining the gut and vaginal T lymphocytes located diffusely within the epithelium or lamina propria but not for generating the gut-associated organized lymphoid tissues. Finally, the impact of alpha E deficiency upon intestinal IEL numbers was greater at 3-4 wk of life than in younger animals, and affected the TCR alpha beta+ CD8+ T cells more than the gamma delta T cells or the TCR alpha beta+ CD4+CD8- population. These findings suggest that alpha E beta 7 is involved in the expansion/recruitment of TCR alpha beta+ CD8+ IEL following microbial colonization. Integrin alpha E-deficient mice will provide an important tool for studying the role of alpha E beta 7 and of alpha E beta 7-expressing mucosal T lymphocytes in vivo.
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| 10. |
- Svanborg, Catharina, et al.
(författare)
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Bacterial adherence and mucosal cytokine responses : Receptors and transmembrane signaling
- 1996
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Ingår i: Ann NY Acad Sci. - : Wiley. ; 797, s. 177-190
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Forskningsöversikt (refereegranskat)abstract
- By attaching to cells or secreted mucosal components, microbes are thought to avoid elimination by the flow of secretions that constantly wash mucosal surfaces. The attached state enhances their ability to trap nutrients and allows the bacteria to multiply more efficiently than do unattached bacterial cells. Attachment is therefore regarded as an end result in itself, and emphasis has been placed on the role of adherence for colonization of mucosal surfaces. Specific adherence was shown to be essential for the tissue tropism that is to guide microbes to their respective sites of colonization/infection. Attachment is not only a mechanism of tissue targeting but also a first step in the pathogenesis of many infections. The attaching bacteria engage in a 'cross-talk' with the host cells through the mutual exchange of signals and responses. Enteropathogenic E. coli induce attaching and effacing lesions. Shigella and Listeria sp. invade the cells and cause actin polymerization. This review describes the ability of bacteria to trigger mucosal inflammation through activation of cells in the mucosal lining. The results suggest that receptors for bacterial adhesins bind their ligands with a high degree of specificity and that ligand-receptor interactions trigger transmembrane signaling events that cause cell activation. Receptors for microbial ligands thus appear to fulfill also the same criteria as those used to define receptors for other classes of ligands such as hormones, growth factors, and cytokines.
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