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- Ragnarsdottir, Bryndis, et al.
(author)
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TLR- and CXCR1-dependent innate immunity: insights into the genetics of urinary tract infections.
- 2008
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In: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 38 Suppl 2, s. 12-20
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Research review (peer-reviewed)abstract
- The susceptibility to urinary tract infection (UTI) is controlled by the innate immune response and Toll like receptors (TLRs) are the sentinels of this response. If productive, TLR4 signalling may initiate the symptomatic disease process. In the absence of TLR4 signalling the infected host instead develops an asymptomatic carrier state. The activation of mucosal TLR4 is also influenced by the properties of the infecting strain, and pathogens use their virulence factors to trigger 'pathogen-specific' TLR4 responses in the urinary tract but do not respond to the asymptomatic carrier strains in patients with asymptomatic bacteriuria (ABU). The TLR4 dependence has been demonstrated in mice and the relevance of low TLR4 function for protection for human disease was recently confirmed in children with asymptomatic bacteriuria, who expressed less TLR4 than age matched controls. Functional chemokines and functional chemokine receptors are crucial for neutrophil recruitment, and for the neutrophil dependent bacterial clearance. Interleukin (IL)-8 receptor deficient mice develop acute septic infections and chronic tissue damage, due to aberrant neutrophil function. This mechanism is relevant for human UTI as pyelonephritis prone children express low levels of the human CXCL8 (Il-8) receptor, CXC chemokine receptor 1 (CXCR1) and often have heterozygous CXCR1 polymorphisms. This review illustrates how intimately the innate response and the susceptibility to UTI are linked and sophisticated recognition mechanisms that rely on microbial virulence and on host TLR4 and CXCR1 signalling.
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| 3. |
- Rao, Komal Umashankar, et al.
(author)
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A broad spectrum anti-bacterial peptide with an adjunct potential for tuberculosis chemotherapy
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Alternative ways to prevent and treat infectious diseases are needed. Previously, we identified a fungal peptide, NZX, that was comparable to rifampicin in lowering M. tuberculosis load in a murine tuberculosis (TB) infection model. Here we assessed the potential synergy between this cationic host defence peptide (CHDP) and the current TB drugs and analysed its pharmacokinetics. We found additive effect of this peptide with isoniazid and ethambutol and confirmed these results with ethambutol in a murine TB-model. In vivo, the peptide remained stable in circulation and preserved lung structure better than ethambutol alone. Antibiotic resistance studies did not induce mutants with reduced susceptibility to the peptide. We further observed that this peptide was effective against nontuberculous mycobacteria (NTM), such as M. avium and M. abscessus, and several Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. In conclusion, the presented data supports a role for this CHDP in the treatment of drug resistant organisms.
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| 4. |
- Godaly, Gabriela
(author)
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Mechanisms of Escherichia coli induced transepithelial neutrophil migration
- 2000
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Doctoral thesis (other academic/artistic)abstract
- Mucosal infections trigger an inflammatory response that includes the secretion of cytokines and the recruitment of neutrophils to the infected site. This thesis describes studies examining the molecular mechanisms of neutrophil migration to sites of mucosal bacterial infection. Escherichia coli (E. coli) infection of epithelial cell layers stimulates chemokine secretion and chemokine receptor expression. Human epithelial cells produced an array of CXC chemokines (e.g., IL-8, GRO, ENA-78, IP-10, MIG) and CC chemokines (e.g., MCP-1, MIP, RANTES) in response to bacterial infection. The chemokine repertoire was shown to be influenced by the fimbrial expression of the infecting strain. Furthermore, E. coli infection increased the expression of chemokine receptors (CXCR1 and CXCR2) on epithelial cells. IL-8 was found to be the major chemoattractant involved in neutrophil migration across infected epithelial cell layers. Transuroepithelial neutrophil migration was also shown to be depending on the level of CXCR1 expression on neutrophils and epithelial cell layers. The in vitro observations were confirmed in an experimental UTI model. Recombinant P or type 1 fimbriated E. coli stimulated chemokine responses and neutrophil recruitment more efficiently than the non-fimbriated controls. The relevance of IL-8 receptor expression was confirmed in vivo using IL-8 receptor knock-out (mIL-8Rh KO) mice. E. coli infection of mIL-8Rh KO mice caused the neutrophils to leave the blood vessels but they were unable to cross the epithelium and accumulated in the tissues. Bacterial clearance was impaired and tissues were destroyed. Subsequent human studies showed a decrease in CXCR1 expression on neutrophils from patients prone to acute pyelonephritis. These results provide a first molecular clue to the host defect in patients prone to acute pyelonephritis.
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| 7. |
- Andersson, Märta, et al.
(author)
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Mycobacterium bovis bacilli Calmette-Guerin regulates leukocyte recruitment by modulating alveolar inflammatory responses.
- 2012
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In: Innate Immunity. - : SAGE Publications. - 1753-4267 .- 1753-4259. ; 18, s. 531-540
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Journal article (peer-reviewed)abstract
- Leukocyte migration into the epithelial compartment is an important feature in the active phase of mycobacterial infections. In this study, we used the Transwell model to investigate the mechanisms behind mycobacteria-induced leukocyte recruitment and investigated the role of TLR2 and TLR4 in this process. Infection of epithelial cells resulted in significantly increased secretion of the neutrophil chemotactic CXCL8 and IL-6, but no secretion of monocyte chemotactic CCL2 or TNF-α was observed. In contrast to epithelial response, mycobacteria-infected neutrophils and monocytes secreted all these cytokines. Corresponding with epithelial cytokine response, mycobacterial infection of the epithelial cells increased neutrophil diapedesis, but decreased monocyte recruitment. However, monocyte recruitment towards mycobacteria infected epithelial cells significantly increased following addition of neutrophil pre-conditioned medium. Mycobacterial infection also increases alveolar epithelial expression of TLR2, but not TLR4, as analyzed by flow cytometry, Western blotting and visualized by confocal microscopy. Blocking of TLR2 inhibited neutrophil recruitment and cytokine secretion, while blocking of TLR4 had a lesser effect. To summarize, we found that primary alveolar epithelial cells produced a selective TLR2-dependent cytokine secretion upon mycobacterial infection. Furthermore, we found that cooperation between cells of the innate immunity is required in mounting proper antimicrobial defence.
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| 9. |
- Bryland, Anna, et al.
(author)
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Citrate treatment reduces endothelial death and inflammation under hyperglycaemic conditions.
- 2012
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In: Diabetes & Vascular Disease Research. - : SAGE Publications. - 1752-8984 .- 1479-1641. ; 9:1, s. 42-51
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Journal article (peer-reviewed)abstract
- Hyperglycaemia and glucose degradation products (GDPs) are closely associated with oxidative stress and inflammation in diabetic patients, a condition that leads to endothelial dysfunction and cardiovascular problems. We evaluated the effect of citrate and gluconate on glucose- and GDP-induced endothelial inflammation by measuring changes in viability, inflammation and function in primary human umbilical vein endothelial cells (HUVECs). The extent of apoptosis/necrosis was measured by flow cytometry and visualised with confocal microscopy by staining with annexin V or propidium iodide, respectively. Protein kinase C-βII (PKC-βII) activation was evaluated with Western blotting. Incubation with glucose (30 mM) and GDP (50 µM) significantly increased PKC-βII expression, endothelial cell death and inflammation. The addition of citrate decreased hyperglycaemia-induced apoptosis (p = 0.021), necrosis (p = 0.04) and reduced PKC-βII expression (p = 0.021) down to background levels. Citrate improved endothelial function by reducing the inflammatory markers(p = 0.01) and by decreasing neutrophil diapedesis (p = 0.012). These results suggest that citrate may have therapeutic potential by reducing hyperglycaemia-induced endothelial inflammation and abolishing endothelial dysfunction.
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| 10. |
- Frendeus, Björn, et al.
(author)
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Interleukin 8 receptor deficiency confers susceptibility to acute experimental pyelonephritis and may have a human counterpart
- 2000
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In: Journal of Experimental Medicine. - 1540-9538. ; 192:6, s. 881-890
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Journal article (peer-reviewed)abstract
- Neutrophils migrate to infected mucosal sites that they protect against invading pathogens. Their interaction with the epithelial barrier is controlled by CXC chemokines and by their receptors. This study examined the change in susceptibility to urinary tract infection (UTI) after deletion of the murine interleukin 8 receptor homologue (mIL-8Rh). Experimental UTIs in control mice stimulated an epithelial chemokine response and increased chemokine receptor expression. Neutrophils migrated through the tissues to the epithelial barrier that they crossed into the lumen, and the mice developed pyuria. In mIL-8Rh knockout (KO) mice, the chemokine response was intact, but the epithelial cells failed to express IL-8R, and neutrophils accumulated in the tissues. The KO mice were unable to clear bacteria from kidneys and bladders and developed bacteremia and symptoms of systemic disease, but control mice were fully resistant to infection. The experimental UTI model demonstrated that IL-8R-dependent mechanisms control the urinary tract defense, and that neutrophils are essential host effector cells. Patients prone to acute pyelonephritis also showed low CXC chemokine receptor 1 expression compared with age-matched controls, suggesting that chemokine receptor expression may also influence the susceptibility to UTIs in humans. The results provide a first molecular clue to disease susceptibility of patients prone to acute pyelonephritis.
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