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Uropathogenic Esherichia coli, multidrug-resistance and induction of host defense mechanisms
Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI), which is one of the most common infections in humans. UPEC strains have acquired successful strategies to subvert the host defense and antibiotics to persist in the urinary tract. The main aim of this thesis was to investigate the host defense mechanisms during a UPEC infection in vitro.

The results showed that SOCS3, a key regulator of the immune system, was increased in bladder epithelial cells in response to a UPEC infection. In addition, UPEC decreased the phosphorylation of the SOCS3 regulated transcription factor STAT3. Nitric oxide (NO), a host-derived antimicrobial factor was shown to increase the release of IL-6 from renal epithelial cells alone or in combination with UPEC. The induction of IL-6 was mediated by ERK1/2 and p38 MAPK signaling and NO was also shown to attenuate UPEC-induced IL-6 mRNA degradation. Furthermore, extended-spectrum beta-lactamase (ESBL)-producing UPEC isolates were shown to induce higher PMN migration and ROS-production, but lower cytokine secretion from renal epithelial cells than susceptible isolates. Ineffective ceftibuten treatment of ESBL isolates induced bacterial filamentation associated with an increased release of ATP and LPS, with a subsequent enhancement of the ESBL evoked host response.

Taken together, the findings show that UPEC can induce SOCS3, a suppressor of host responses and that NO can regulate proinflammatory mediators. In addition, the data suggest that there are differences between ESBL- and non-ESBL-producing isolates ability to evoke a host response. Exposing resistant isolates to ineffective antibiotics was shown to alter the evoked host response.

Place, publisher, year, edition, pages
Örebro: Örebro universitet , 2014. , p. 87
Series
Örebro Studies in Medicine, ISSN 1652-4063 ; 105
Keywords [en]
Urinary tract infection, uropathogenic Escherichia coli, suppressor of cytokine signalling 3, nitric oxide, cytokines, extended-spectrum beta-lactamases, filamentation, IL-6
National Category
Medical and Health Sciences
Research subject
Biomedicine
Identifiers
URN: urn:nbn:se:oru:diva-33556ISBN: 978-91-7529-013-3 (print)OAI: oai:DiVA.org:oru-33556DiVA, id: diva2:693293
Public defence
2014-05-23, Campus USÖ (Universitetssjukhuset) X-huset, Hörsal C1, Södra Grev Rosengatan, 703 62 Örebro, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2014-02-04 Created: 2014-02-04 Last updated: 2017-10-17Bibliographically approved
List of papers
1. Expression of suppressor of cytokine signalling 3 (SOCS3) in human bladder epithelial cells infected with uropathogenic Escherichia coli
Open this publication in new window or tab >>Expression of suppressor of cytokine signalling 3 (SOCS3) in human bladder epithelial cells infected with uropathogenic Escherichia coli
2013 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 121, no 2, p. 158-167Article in journal (Refereed) Published
Abstract [en]

Suppressor of cytokine signalling (SOCS) proteins inhibit pro-inflammatory signalling mediated by Janus-activated kinase (JAK)-signal transducer and activator of transcription (STAT) pathways. To evade the immune response some pathogens appear to modify the host SOCS proteins. Uropathogenic Escherichia coli (UPEC) are able to subvert the host response evoked by bladder epithelial cells, but the mechanisms are not fully understood. The objective of this study was to investigate whether UPEC can modify the host SOCS and STAT3 response. Real time RT-PCR studies demonstrated an increased SOCS1 and SOCS3 expression in the isolated human bladder epithelial cell lines (RT-4 and 5637) in response to cytokines. UPEC strain IA2 increased SOCS3, but not SOCS1, mRNA levels with a peak at 6 h after infection. The increase of SOCS3 was confirmed at the protein level by Western blotting. The UPEC strain IA2 caused a time-dependent decrease in the phosphorylation of STAT3. This study demonstrates that UPEC are able to affect SOCS3 and STAT3 signalling in human uroepithelial cells. The finding that UPEC are able to induce mediators involved in suppression of host cytokine signalling may help to elucidate how UPEC may circumvent the host response during urinary tract infection.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-26375 (URN)10.1111/j.1600-0463.2012.02951.x (DOI)000313830700010 ()23030674 (PubMedID)
Note

Funding Agency:

Swedish Medical Research Council 65X-12601-11 

Faculty of Medicine and Health at Örebro University 

Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
2. Nitric oxide activates IL-6 production and expression in human renal epithelial cells
Open this publication in new window or tab >>Nitric oxide activates IL-6 production and expression in human renal epithelial cells
Show others...
2012 (English)In: American Journal of Nephrology, ISSN 0250-8095, E-ISSN 1421-9670, Vol. 36, no 6, p. 524-530Article in journal (Refereed) Published
Abstract [en]

Background/Aims: Increased nitric oxide (NO) production or inducible form of NO synthase activity have been documented in patients suffering from urinary tract infection (UTI), but the role of NO in this infection is unclear. We investigated whether NO can affect the host response in human renal epithelial cells by modulating IL-6 production and mRNA expression.

Methods: The human renal epithelial cell line A498 was infected with a uropathogenic Escherichia coli (UPEC) strain and/or the NO donor DETA/NO. The IL-6 production and mRNA expression were evaluated by ELISA and real-time RT-PCR. IL-6 mRNA stability was evaluated by analyzing mRNA degradation by real-time RT-PCR.

Results: DETA/NO caused a significant (p < 0.05) increase in IL-6 production. Inhibitors of p38 MAPK and ERK1/2 signaling, but not JNK, were shown to significantly suppress DETA/NO-induced IL-6 production. UPEC-induced IL-6 production was further increased (by 73 ± 23%, p < 0.05) in the presence of DETA/NO. The IL-6 mRNA expression increased 2.1 ± 0.17-fold in response to DETA/NO, while the UPEC-evoked increase was pronounced (20 ± 4.5-fold). A synergistic effect of DETA/NO on UPEC-induced IL-6 expression was found (33 ± 7.2-fold increase). The IL-6 mRNA stability studies showed that DETA/NO partially attenuated UPEC-induced degradation of IL-6 mRNA.

Conclusions: NO was found to stimulate IL-6 in renal epithelial cells through p38 MAPK and ERK1/2 signaling pathways and also to increase IL-6 mRNA stability in UPEC-infected cells. This study proposes a new role for NO in the host response during UTI by modulating the transcription and production of the cytokine IL-6.

Place, publisher, year, edition, pages
Basel, Switzerland: S. Karger, 2012
Keywords
Nitric oxide, urinary tract infections, il-6, mapk signaling, renal epithelial cells
National Category
Medical and Health Sciences Microbiology in the medical area
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-26534 (URN)10.1159/000345351 (DOI)000312916200004 ()23183248 (PubMedID)2-s2.0-84869889861 (Scopus ID)
Available from: 2012-11-28 Created: 2012-11-28 Last updated: 2018-01-12Bibliographically approved
3. Comparison of host response mechanisms evoked by extended spectrum beta lactamase (ESBL)- and non-ESBL-producing uropathogenic E. coli
Open this publication in new window or tab >>Comparison of host response mechanisms evoked by extended spectrum beta lactamase (ESBL)- and non-ESBL-producing uropathogenic E. coli
Show others...
2013 (English)In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 13, article id 181Article in journal (Refereed) Published
Abstract [en]

Background: Infections caused by extended spectrum beta-lactamases (ESBL)-producing bacteria have been emerging worldwide and the majority of ESBL-producing E. coli strains are isolated from patients with urinary tracts infections. The purpose of this study was to compare the host-response mechanisms in human polymorphonucleated leukocytes (PMN) and renal epithelial cells when stimulated by ESBL-or non-ESBL-producing uropathogenic E. coli (UPEC) isolates. The host-pathogen interaction of these ESBL-producing strains in the urinary tract is not well studied.

Results: The ability of ESBL strains to evoke ROS-production from PMN cells was significantly higher than that of the non-ESBL strains. The growth of ESBL strains was slightly suppressed in the presence of PMN compared to non-ESBL strains after 30 min and 2 h, but the opposite was observed after 5 and 6 h. The number of migrating PMN was significantly higher in response to ESBL strains compared to non-ESBL strains. Stimulation of A498 cells with ESBL strains elicited lower production of IL-6 and IL-8 compared to non-ESBL strains.

Conclusion: Significant differences in host-response mechanisms were identified when host cells were stimulated by ESBL-or non-ESBL producing strains. The obtained results on the early interactions of ESBL-producing strains with the host immune system may provide valuable information for management of these infections.

Place, publisher, year, edition, pages
London, United Kingdom: BioMed Central, 2013
Keywords
Extended spectrum beta-lactamases, Urinary tract infections, Renal epithelial cells, Polymorphonucleated leukocytes, Uropathogenic E. coli
National Category
Medical and Health Sciences Microbiology
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-30515 (URN)10.1186/1471-2180-13-181 (DOI)000322659500001 ()24059789 (PubMedID)2-s2.0-84880913688 (Scopus ID)
Available from: 2013-08-30 Created: 2013-08-30 Last updated: 2018-05-21Bibliographically approved
4. Antibiotic-induced filamentation of extended spectrum beta lactamase (ESBL)-producing uropathogenic E. coli alters host cell responses during an in vitro infection
Open this publication in new window or tab >>Antibiotic-induced filamentation of extended spectrum beta lactamase (ESBL)-producing uropathogenic E. coli alters host cell responses during an in vitro infection
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Inadequate and delayed antibiotic treatment of extended spectrum beta-lactamase (ESBL)- producing isolates have been associated with increased mortality of affected patients. The purpose of this study was to compare the host response of human renal epithelial cells and polymorphonuclear leukocyte (PMN) cells when infected by ESBL-producing uropathogenic E. coli (UPEC) isolates in the presence or absence of ineffective antibiotics.

The renal epithelial cell line A498 and PMN cells were stimulated with ESBLproducing UPEC isolates in the presence or absence of three different antibiotics (trimetoprim, ceftibuten and ciprofloxacin). Host cell responses were evaluated as release of cytokines (IL-6, IL-8), reactive oxygen species (ROS), ATP and endotoxins. Bacterial morphology and PMNphagocytosis were evaluated by microscopy.

In the presence of ceftibuten, 2 out of 3 examined ESBL-isolates changed their morphology into a filamentous form. The presence of ceftibuten enhanced IL-6, IL-8 and ROS-production from host cells, but only from cells stimulated by the filamentous isolates. The bacterial supernatant and not the filamentous bacteria per se was responsible for the increased release of IL-6, IL-8 and ROS. Increased endotoxin and ATP levels were found in the bacterial supernatants from filamentous isolates. Apyrase decreased IL-6 secretion from A498 cells and polymyxin B abolished the increased ROS production from PMN cells. PMN were able to inhibit the bacterial growth of some ESBL-isolates in the presence of ceftibuten. In conclusion, antibiotic-induced filamentation of ESBL-producing UPEC isolates and the associated release of ATP and endotoxins can alter the host cell response in the urinary tract.

Keywords
urinary tract infections, renal epithelial cells, polymorphonucleated leukocytes, uropathogenic E. coli, extended spectrum beta-lactamases, filamentous bacteria
National Category
Medical and Health Sciences
Research subject
Biomedicine
Identifiers
urn:nbn:se:oru:diva-34891 (URN)
Available from: 2014-04-28 Created: 2014-04-28 Last updated: 2017-10-17Bibliographically approved

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Demirel, Isak

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