| 1. |
- Calander, Ann-Marie, 1957, et al.
(författare)
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Impact of staphylococcal protease expression on the outcome of infectious arthritis
- 2004
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Ingår i: Microbes Infect. - : Elsevier BV. - 1286-4579. ; 6:2, s. 202-6
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Tidskriftsartikel (refereegranskat)abstract
- The exoproteases of Staphylococcus aureus have been proposed as virulence factors during S. aureus infections. To investigate this, we used the wild-type S. aureus strain 8325-4 and its mutants devoid of aureolysin, serine protease, and cysteine protease, respectively, in a well-established model of septic arthritis in mice. The inactivation of the exoprotease genes did not affect the frequency or the severity of joint disease. We conclude that in the model of haematogenously spread staphylococcal arthritis, the bacterial proteases studied do not act as virulence factors.
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| 2. |
- Andersson, Karin, 1972, et al.
(författare)
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Down-regulation of survivin alleviates experimental arthritis.
- 2015
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Ingår i: Journal of leukocyte biology. - 1938-3673. ; 97:1, s. 135-45
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Tidskriftsartikel (refereegranskat)abstract
- Survivin is a proto-oncogene that regulates cell division and apoptosis. It is a molecular marker of cancer. Recently, survivin has emerged as a feature of RA, associated with severe joint damage and poor treatment response. The present study examined if inhibition of survivin affects experimental arthritis, which was induced in mBSA-immunized mice by an injection of mBSA in the knee joint or developed spontaneously in collagen type II-immunized mice. The inhibition of survivin transcription by a lentivirus shRNA construct alleviated joint inflammation and reduced bone damage. The inhibition of survivin reduced the levels of metalloproteinases, β-catenin, and vimentin, limiting the invasive capacity of synovia, while no inhibition of osteoclastogenesis could be found. The inhibition of survivin led to a p53-independent reduction of T cell proliferation and favored the transcription and activity of Blimp-1, which limited IL-2 production and facilitated formation of regulatory Foxp3(+)CD4(+) and effector CD8(+) T cells. The study shows that the inhibition of survivin is sufficient to reduce joint inflammation and bone damage in preclinical models of arthritis. Antiarthritic effects of survivin inhibition are related to p53-independent control of lymphocyte proliferation.
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| 3. |
- Baran, M, et al.
(författare)
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SURVIVIN IS AN ESSENTIAL MEDIATOR OF ARTHRITIS INTERACTING WITH UROKINASE SIGNALLING.
- 2009
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Ingår i: Journal of cellular and molecular medicine. - : Wiley. - 1582-4934 .- 1582-1838. ; 13:9B, s. 3797-3808
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT Proto-oncogene survivin has recently been identified as a prognostic marker distinguishing patients with destructive rheumatoid arthritis (RA). In the present material of 132 RA patients and 82 controls the levels of survivin correlated to urokinase (uPA) (r=0.46), a plasminogen activator over expressed in inflamed joints and known to exhibit potent arthritogenic properties. Here we evaluate the functional relationship between these proteins using primary synovial fibroblasts and leukocytes of RA patients, human monocytic (THP-1) and fibroblast (MRC-5) cell lines. Using inhibitors of intracellular signalling we show that uPA and survivin share common transduction pathways being in synovial fibroblasts dependent on the activity of tyrosine kinases, PI3-kinase and MEK. Moreover, uPA production is significantly reduced in fibroblasts if survivin synthesis has been silenced by siRNA. Importantly, silencing of survivin in fibroblasts prevented their invasive growth in knee joints of SCID mice. Interaction of uPA with receptor up regulates survivin expression in leukocytes. In turn, survivin is required for the upregulation of uPA receptor on cell surface. These findings indicate that survivin is an essential mediator of arthritogenic properties of uPA regulating its synthesis in synovial fibroblasts and uPAR expression in leukocytes. Close correlation between survivin and uPA levels in patients with RA supports the importance of this connection for the pathogenesis of arthritis.
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| 4. |
- Bian, Li, et al.
(författare)
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Dichloroacetate alleviates development of collagen II-induced arthritis in female DBA/1 mice
- 2009
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Ingår i: ARTHRITIS RESEARCH and THERAPY. - : BioMed Central. - 1478-6354 .- 1478-6362. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Dichloroacetate (DCA) has been in clinical use for the treatment of lactacidosis and inherited mitochondrial disorders. It has potent anti-tumor effects both in vivo and in vitro, facilitating apoptosis and inhibiting proliferation. The proapoptotic and anti-proliferative properties of DCA prompted us to investigate the effects of this compound in arthritis. Methods In the present study, we used DCA to treat murine collagen type II (CII)-induced arthritis (CIA), an experimental model of rheumatoid arthritis. DBA/1 mice were treated with DCA given in drinking water. Results Mice treated with DCA displayed much slower onset of CIA and significantly lower severity (P less than 0.0001) and much lower frequency (36% in DCA group vs. 86% in control group) of arthritis. Also, cartilage and joint destruction was significantly decreased following DCA treatment (P = 0.005). Moreover, DCA prevented arthritis-induced cortical bone mineral loss. This clinical picture was also reflected by lower levels of anti-CII antibodies in DCA-treated versus control mice, indicating that DCA affected the humoral response. In contrast, DCA had no effect on T cell-or granulocyte-mediated responses. The beneficial effect of DCA was present in female DBA/1 mice only. This was due in part to the effect of estrogen, since ovariectomized mice did not benefit from DCA treatment to the same extent as sham-operated controls (day 30, 38.7% of ovarectomized mice had arthritis vs. only 3.4% in sham-operated group). Conclusion Our results indicate that DCA delays the onset and alleviates the progression of CIA in an estrogen-dependent manner.
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| 5. |
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| 6. |
- Boström, Elisabeth Almer, 1983, et al.
(författare)
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Resistin and insulin/insulin-like growth factor signaling in rheumatoid arthritis.
- 2011
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Ingår i: Arthritis and rheumatism. - : Wiley. - 1529-0131 .- 0004-3591. ; 63:10, s. 2894-904
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Tidskriftsartikel (refereegranskat)abstract
- Human resistin has proinflammatory properties that activate NF-κB-dependent pathways, whereas its murine counterpart is associated with insulin resistance. The aim of this study was to examine potential cross-talk between resistin and insulin/insulin-like growth factor (IGF) signaling in rheumatoid arthritis (RA).
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| 7. |
- Brisslert, Mikael, 1974, et al.
(författare)
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S100A4 regulates the Src-tyrosine kinase dependent differentiation of Th17 cells in rheumatoid arthritis
- 2014
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Ingår i: Biochimica Et Biophysica Acta-Molecular Basis of Disease. - : Elsevier BV. - 0925-4439. ; 1842:11, s. 2049-2059
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To evaluate the role of S100A4, a calcium-binding regulator of nonmuscle myosin assembly, for T-cell responses in rheumatoid arthritis. Methods: Arthritis was induced in the methylated bovine serum albumin (mBSA)-immunized mice lacking the entire S100A4 protein (S100A4KO) and in wild-type counterparts treated with short hairpin ribonucleic acid (shRNA)-lentiviral constructs targeting S100A4 (S100A4-shRNA). The severity of arthritis was evaluated morphologically. T-cell subsets were characterized by the expression of master transcription factors, and functionally by proliferation activity and cytokine production. The activity of the Scr-kinases Fyn and Lck was assessed by the autophosphorylation of C-terminal thyrosine and by the phosphorylation of the CD5 cytodomain. The interaction between S100A4 and the CD5 cytodomain was analysed by nuclear magnetic resonance spectrophotometry. Results: S100A4-deficient mice (S100A4KO and S100A4-shRNA) had significantly alleviated morphological signs of arthritis and joint damage. Leukocyte infiltrates in the arthritic joints of S100A4-deficient mice accumulated Foxp3(+) Treg cells, while the number of ROR gamma t(+) and (pTyr705)STAT3(+) cells was reduced. S100A4-deficient mice had a limited formation of Th17-cells with low retinoic acid orphan receptor gamma t (ROR gamma t) mRNA and IL17 production in T-cell cultures. S100A4-deficient mice had a low expression and activity of T-cell receptor (TCR) inhibitor CD5 and low (pTyr705)STAT3 (signal transducer and activator of transcription 3), which led to increased (pTyr352)ZAP-70 (theta-chain associated protein kinase of 70 kDa), lymphocyte proliferation and production of IL2. In vitro experiments showed that S100A4 directly binds Lck and Fyn and reciprocally regulates their kinase activity towards the CD5 cytodomain. Spectrometry demonstrates an interaction between the CD5 cytodomain and EF2-binding sites of S100A4. Conclusion: The present. study demonstrates that S100A4 plays an important part in the pathogenesis of arthritis. It controls CD5-dependent differentiation of Th17 cells by regulating the activity of the Src-family kinases Lck and Fyn. (C) 2014 Elsevier B.V. All rights reserved.
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| 8. |
- Carroll, R. K., et al.
(författare)
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Identification of an intracellular M17 family leucine aminopeptidase that is required for virulence in Staphylococcus aureus
- 2012
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Ingår i: Microbes and Infection. - : Elsevier BV. - 1286-4579. ; 14:11, s. 989-999
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is a highly virulent bacterial pathogen capable of causing a variety of ailments throughout the human body. It is a major public health concern due to the continued emergence of highly pathogenic methicillin resistant strains (MRSA) both within hospitals and in the community. Virulence in S. aureus is mediated by an array of secreted and cell wall associated virulence factors, including toxins, hemolysins and proteases. In this work we identify a (l) under bar eucine (a) under bar mino (p) under bar eptidase (LAP, pepZ) that strongly impacts the pathogenic abilities of S. aureus. Disruption of the pepZ gene in either Newman or USA300 resulted in a dramatic attenuation of virulence in both localized and systemic models of infection. LAP is required for survival inside human macrophages and gene expression analysis shows that pepZ expression is highest in the intracellular environment. We examine the cellular location of LAP and demonstrate that it is localized to the bacterial cytosol. These results identify for the first time an intracellular leucine aminopeptidase that influences disease causation in a Gram-positive bacterium. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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| 9. |
- Collins, Vincent, 1962, et al.
(författare)
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Endogenously oxidized mitochondrial DNA induces in vivo and in vitro inflammatory responses
- 2004
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Ingår i: J Leukoc Biol. - : Oxford University Press (OUP). - 0741-5400. ; 75:6, s. 995-1000
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Tidskriftsartikel (refereegranskat)abstract
- We report that mitochondrial DNA (mtDNA) is inflammatogenic in vitro and in vivo as a result of the presence of unmethylated CpG sequences and its oxidative status. Purified human and murine mtDNAs induced arthritis when injected intra-articularly (i.a.) in mice. Importantly, oligodeoxynucleotide that contained a single oxidatively damaged base also induced arthritis when injected i.a. in mice. In contrast, neither human nor murine nuclear DNA induced inflammation. mtDNA-induced arthritis was neither B cell- nor T cell-dependent but was mediated by monocytes/macrophages. mtDNA-induced nuclear factor-kappaB stimulation resulted in the production of tumor necrosis factor alpha, a potent, arthritogenic factor. Finally, extracellular mtDNA was detected in the synovial fluids of rheumatoid arthritis patients but not of control subjects. We conclude that endogenous mtDNA displays inflammatogenic properties as a result of its content of unmethylated CpG motifs and oxidatively damaged adducts.
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| 10. |
- Cosgrove, K., et al.
(författare)
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Catalase (KatA) and alkyl hydroperoxide reductase (AhpC) have compensatory roles in peroxide stress resistance and are required for survival, persistence, and nasal colonization in Staphylococcus aureus
- 2007
-
Ingår i: J Bacteriol. - 0021-9193. ; 189:3, s. 1025-35
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative-stress resistance in Staphylococcus aureus is linked to metal ion homeostasis via several interacting regulators. In particular, PerR controls the expression of a regulon of genes, many of which encode antioxidants. Two PerR regulon members, ahpC (alkylhydroperoxide reductase) and katA (catalase), show compensatory regulation, with independent and linked functions. An ahpC mutation leads to increased H2O2 resistance due to greater katA expression via relief of PerR repression. Moreover, AhpC provides residual catalase activity present in a katA mutant. Mutation of both katA and ahpC leads to a severe growth defect under aerobic conditions in defined media (attributable to lack of catalase activity). This results in the inability to scavenge exogenous or endogenously produced H2O2, resulting in accumulation of H2O2 in the medium. This leads to DNA damage, the likely cause of the growth defect. Surprisingly, the katA ahpC mutant is not attenuated in two independent models of infection, which implies reduced oxygen availability during infection. In contrast, both AhpC and KatA are required for environmental persistence (desiccation) and nasal colonization. Thus, oxidative-stress resistance is an important factor in the ability of S. aureus to persist in the hospital environment and so contribute to the spread of human disease.
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| 11. |
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| 12. |
- Erlandsson, Malin, 1972, et al.
(författare)
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Expression of metastasin S100A4 is essential for bone resorption and regulates osteoclast function.
- 2013
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Ingår i: Biochimica et biophysica acta. - : Elsevier BV. - 0006-3002. ; 1833:12, s. 2653-2663
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Tidskriftsartikel (refereegranskat)abstract
- S100A4 is a Ca-binding protein that regulates cell growth, survival, and motility. The abundant expression of S100A4 in rheumatiod arthritis contributes to the invasive growth of joint tissue and to bone damage. In the present study, we analysed the role of S100A4 in bone homeostasis.
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| 13. |
- Erlandsson, Malin, 1972, et al.
(författare)
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IGF-1R signalling contributes to IL-6 production and T cell dependent inflammation in rheumatoid arthritis.
- 2017
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Ingår i: Biochimica et Biophysica Acta - Molecular basis of disease. - : Elsevier BV. - 0005-2728 .- 0925-4439. ; 1863:9, s. 2158-2170
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Tidskriftsartikel (refereegranskat)abstract
- Signalling through insulin-like growth factor 1 receptor (IGF-1R) is essential for cell survival, but may turn pathogenic in uncontrolled tissue growth in tumours. In rheumatoid arthritis (RA), the IGF-1R signalling is activated and supports expansion of the inflamed synovia.In the present study, we assess if disruption of IGF-1R signalling resolves arthritis.Clinical associations of IGF-1R expression in leukocytes of the peripheral blood were studied in 84 RA patients. Consequences of the IGF-1R signalling inhibition for arthritis were studied in mBSA immunised Balb/c mice treated with NT157 compound promoting degradation of insulin receptor substrates.In RA patients, high expression of IGF-1R in leukocytes was associated with systemic inflammation as verified by higher expression of NF-kB, serum levels of IL6 and erythrocyte sedimentation rate, and higher pain perception. Additionally, phosphorylated IGF-1R and STAT3 enriched T cells infiltrate in RA synovia. Treatment with NT157 inhibited the phosphorylation of IGF-1R and STAT3 in synovia, and alleviated arthritis and joint damage in mice. It also reduced expression of IGF-1R and despaired ERK and Akt signalling in spleen T cells. This limited IL-6 production, changed RoRgt/FoxP3 balance and IL17 levels.IGF-1R signalling contributes to T cell dependent inflammation in arthritis. Inhibition of IGF-1R on the level of insulin receptor substrates alleviates arthritis by restricting IL6-dependent formation of Th17 cells and may open for new treatment strategies in RA.
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| 14. |
- Erlandsson, Malin, 1972, et al.
(författare)
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Metastasin S100A4 is a mediator of sex hormone-dependent formation of the cortical bone.
- 2013
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Ingår i: Molecular endocrinology (Baltimore, Md.). - : The Endocrine Society. - 1944-9917 .- 0888-8809. ; 27:8, s. 1311-21
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Tidskriftsartikel (refereegranskat)abstract
- S100A4 is a Ca-binding protein participating in regulation of cell growth, survival, and motility. Here we studied the role of S100A4 protein in sex hormone-regulated bone formation. Bone mineral density in the trabecular and cortical compartments was evaluated in female S100A4 knockout (KO), in matched wild-type (WT) counterparts, and in WT mice treated with lentiviral small hairpin RNA construct inhibiting the S100A4 gene transcription or with a nontargeting construct, by peripheral quantitative computed tomography. The effect of sex hormones on bone was measured 5 weeks after ovariectomy (OVX) and/or dehydroepiadrosterone treatment. S100A4KO had an excessive trabecular and cortical bone formation compared with the age- and sex-matched WT mice. S100A4KO had an increased periosteal circumference (P = .001), cortical thickness (P = .056), and cortical area (P = .003), which predicted 20% higher bone strength in S100A4KO (P = .013). WT mice treated with small hairpin RNA-S100A4 showed an increase of the cortical bone parameters in a fashion identical with S100A4KO mice, indicating the key role of S100A4 in the changed bone formation. S100A4KO mice had higher serum levels of osteocalcin and a higher number of osteocalcin-positive osteoblasts under the periosteum. OVX-S100A4 resulted in the loss of the cortical bone supported by high CTX-I levels, whereas no such changes were observed in OVX-WT mice. S100A4KO mice resisted the dehydroepiadrosterone -induced bone formation observed in the WT counterparts. Our study indicates that S100A4 is a regulator of bone formation, which inhibits bone excess in the estrogen-sufficient mice and prevents the cortical bone loss in the estrogen-deprived mice.
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| 15. |
- Fei, Ying, et al.
(författare)
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The combination of a tumor necrosis factor inhibitor and antibiotic alleviates staphylococcal arthritis and sepsis in mice.
- 2011
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Ingår i: The Journal of infectious diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 204:3, s. 348-57
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Tidskriftsartikel (refereegranskat)abstract
- (See the editorial commentary by Chow, on pages 332-4) Background.Despite advances in medical practices, in recent decades permanent reductions in joint function have not been achieved, and the high mortality rate of patients with staphylococcal septic arthritis has not substantially improved. Methods.We evaluated the effects of a combined tumor necrosis factor (TNF) inhibitor and antibiotic therapy on the course of Staphylococcus aureus arthritis and sepsis in mice. Results.Treatment with the combination of a TNF inhibitor and an antibiotic resulted in a quicker relief of clinical arthritis in mice with septic arthritis, compared with an antibiotic monotherapy. Both histopathologically verified synovitis and the extent of joint destruction were reduced by this combined treatment. Importantly, anti-TNF treatment significantly improved the survival rate of mice with S. aureus sepsis and staphylococcal enterotoxin shock syndrome; this effect might be the result of a partial restoration of the hemostatic balance between coagulation and fibrinolysis. Finally, we demonstrated that anti-TNF treatment downregulates high-mobility group protein B1 in staphylococcal enterotoxin shock syndrome. Conclusions.Thus, simultaneous systemic TNF inhibition and antibiotic therapy has beneficial effects on the outcome of S. aureus arthritis and sepsis in a mouse model, suggesting that the combination of a TNF inhibitor and antibiotics represents a novel therapeutic strategy for the treatment of staphylococcal infections.
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| 16. |
- George-Chandy, Annie, 1969, et al.
(författare)
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Th17 development and autoimmune arthritis in the absence of reactive oxygen species
- 2008
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 38:4, s. 1118-1126
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Tidskriftsartikel (refereegranskat)abstract
- Dendritic cells (DC) express a functional NADPH oxidase and produce reactive oxygen species (ROS) upon interaction with microbes and T cells. Exposure to ROS leads to DC activation and maturation, as evidenced by phenotypic and functional changes. We have evaluated how endogenous ROS production affects the cytokine secretion pattern and T cell-activating capacity of bone marrow-derived murine DC. DC treated with ROS scavengers, as well as DC from mice that lack a functional NADPH oxidase (and thereby inherently deficient in ROS production) produced significantly increased levels of IL-1β, IL-6, TNF-α and TGF-β in response to microbial activation. DC deficient in ROS production induced high levels of IFN-γ and IL-17 in responding T cells after Ag-specific or superantigen-induced activation. Finally, we show that ROS deficiency affected the induction of a T cell-dependent inflammatory condition, collagen-induced arthritis (CIA). C57BL/6 mice that lack a functional NADPH oxidase developed a severe and erosive CD4-dependent CIA, whereas the majority of the congenic wild-type animals remained healthy. These data suggest that ROS act as immunomodulators in DC-driven T cell activation and perhaps also in T cell-dependent immunopathology.
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| 17. |
- Gjertsson, Inger, 1962, et al.
(författare)
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Formylated Peptides Are Important Virulence Factors in Staphylococcus aureus Arthritis in Mice.
- 2012
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Ingår i: The Journal of infectious diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 205:2, s. 305-311
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Tidskriftsartikel (refereegranskat)abstract
- Background.Staphylococcus aureus is the most common pathogen causing septic arthritis in humans. The affected joints are often rapidly and permanently damaged despite antibiotic treatment, indicating that the elicited host immune response contributes substantially to joint destruction. Bacterial formylated peptides are important chemotactic molecules mediating neutrophil recruitment into infected tissues as an important first step of host defense against invading bacteria. The role of formylated peptides in S. aureus infections has been unknown.Methods.Mice were intravenously inoculated with wild-type S. aureus strain RN4220 or its isogenic mutant strain (Δfmt) lacking the ability to produce formylated peptides. The development of arthritis was followed clinically and histopathologically.Results.Mice inoculated with the formyl peptide-producing wild-type strain showed a significantly increased frequency and severity of arthritis and subsequent joint destruction as compared with Δfmt mutant strain-inoculated mice. The wild-type S. aureus strain also induced significantly more weight loss than the Δfmt mutant strain. The recruitment of neutrophils into infected kidneys and synovial tissue was significantly higher in mice inoculated with the wild-type strain.Conclusions.Our data show that formylated peptides function as important virulence factors in S. aureus arthritis, partly by mediating neutrophil recruitment, which contributes substantially to the joint damage.
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| 18. |
- Jonsson, Ing-Marie, 1949, et al.
(författare)
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Ethanol prevents development of destructive arthritis
- 2007
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Ingår i: Proc Natl Acad Sci U S A. - Washington, DC : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 104:1, s. 258-63
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Tidskriftsartikel (refereegranskat)abstract
- Environmental factors are thought to play a major role in the development of rheumatoid arthritis. Because the use of ethanol is widespread, we assessed the role of ethanol intake on the propensity to develop chronic arthritis. Collagen type II-immunized mice were given water or water containing 10% (vol/vol) ethanol or its metabolite acetaldehyde. Their development of arthritis was assessed, as well as the impact of ethanol on leukocyte migration and activation of intracellular transcription factors. Mice exposed daily to this dose of ethanol did not display any liver toxicity, and the development of erosive arthritis was almost totally abrogated. In contrast, the antibody-mediated effector phase of collagen-induced arthritis was not influenced by ethanol exposure. Also, the major ethanol metabolite, acetaldehyde, prevented the development of arthritis. This antiinflammatory and antidestructive property of ethanol was mediated by (i) down-regulation of leukocyte migration and (ii) up-regulation of testosterone secretion, with the latter leading to decreased NF-kappaB activation. We conclude that low but persistent ethanol consumption delays the onset and halts the progression of collagen-induced arthritis by interaction with innate immune responsiveness.
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| 19. |
- Jonsson, Ing-Marie, et al.
(författare)
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I Can’t Hear You? Driver’s Interacting with Male or Female Voices in Native or Non-Native Language
- 2011
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Ingår i: Universal Access in Human-Computer Interaction. Context Diversity, Part III. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642216657 - 9783642216664 ; , s. 298-305
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Konferensbidrag (refereegranskat)abstract
- Many vehicles today are equipped with navigation systems, and all of these systems use speech or a combination of speech and graphics to provide drivers with directions to their destinations. This study investigates the effect of gender of voice when providing driving instructions in English to drivers that are non-native speakers of English. In a 2(native/non-native) by 2(gender of voice) between participant study, 40 participants in age group 18-25 drove in a driving simulator for 25 minutes with navigation information system that gave drivers directions to a set destination. Results show that gender of voice did not affect native English speaking drivers. For non-native speakers, however, a female voice worked better for both female and male drivers. Non-native speakers consistently missed to act on navigational information give by the male voice. Design implications for voice systems are discussed.
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| 20. |
- Jonsson, Ing-Marie, 1960-, et al.
(författare)
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Impact of Voice Variation in Speech-Based In-Vehicle Systems on Attitude and Driving Behavior
- 2009
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Ingår i: Human Factors and Ergonomics Society Europe Chapter (HFES).
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Konferensbidrag (refereegranskat)abstract
- Automobile manufacturers are making information systems available in all vehicles. Mostsystems are screen based, but increasingly systems are either hybrids (screen/speech) orspeech based. Speech systems in vehicles may have advantages over screen based in-vehiclesystems; literature suggests that speech can be less distracting than screen-based interactions.Nonetheless, using speech systems in the car also introduces social and attitudinal effects.Voices are not neutral! Voices carry socio-economic cues including indicators of gender, age,personality, emotional state, ethniticity, education and social status. Perception ofinformation presented by the voice is influenced by the perception of the voice demographics.This is further complicated by different individuals perceiving voices in different ways. A voicethat is seen as positive by one individual can be perceived negatively by another. We presentresults from a number of driving simulator studies of speech based in-vehicle systems. These studiesshow that speech based in-vehicle systems can affect drivers’ attitude and drivingperformance. Attitude and performance can be improved, but the effect of the voice can also proveharmful for driving behaviour and driving safety. This makes it important to include the voice as adesign parameter of speech-based in-vehicle systems.
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| 21. |
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| 22. |
- Jonsson, Ing-Marie, 1949, et al.
(författare)
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mgrA regulates staphylococcal virulence important for induction and progression of septic arthritis and sepsis.
- 2008
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Ingår i: Microbes and infection / Institut Pasteur. - : Elsevier BV. - 1286-4579. ; 10:12-13, s. 1229-35
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Tidskriftsartikel (refereegranskat)abstract
- Septic arthritis and sepsis are common and feared complications of staphylococcal infections, and the increasing antibiotic resistance among staphylococci urge the extended research for virulence factors involved in these diseases. Staphylcoccus aureus produces a number of virulence factors controlled by several global regulatory genes including agr and sarA. MgrA is a recently identified global regulator, belonging to the SarA subfamily, which upregulates expression of several virulence factors including capsule and sortase. In addition, MgrA has been shown to regulate antibiotic resistance and decrease bacterial autolysis. In this study we have assessed the role of mgrA gene expression on induction and progression of septic arthritis and sepsis. Mice inoculated with the mgrA mutant displayed significantly less severe arthritis and showed a significantly better weight development, than wild-type inoculated mice. Importantly, all 10 mice inoculated with the mgrA mutant survived as compared to 70% mortality in the wild-type inoculated mice (p=0.003). In addition, the mgrA mutant showed significantly less bacterial persistence in kidneys as compared to the wild-type strain. We conclude that mgrA regulates virulence factors important for establishment and progression of septic arthritis and sepsis.
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| 23. |
- Jonsson, Ing-Marie, 1949, et al.
(författare)
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Role of fibrinogen-binding adhesin expression in septic arthritis and septicemia caused by Streptococcus agalactiae
- 2005
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Ingår i: J Infect Dis. - 0022-1899. ; 192:8, s. 1456-64
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Streptococcus agalactiae (group B streptococcus) is an important human pathogen that causes neonatal pneumonia, sepsis, septic arthritis, and meningitis, as well as severe infections in immunocompromised adult patients. The streptococci produce several molecules important for virulence. METHODS: We used a murine model of sepsis and septic arthritis to assess the role of FbsA, a fibrinogen-binding adhesin of S. agalactiae as a virulence determinant. NMRI mice were inoculated intravenously with S. agalactiae strains isogenic for the expression of FbsA. RESULTS: Inoculation with wild-type (wt) streptococci resulted in significantly higher mortality, more-pronounced weight decrease, and more-severe arthritis, compared with inoculation with the FbsA mutant isogenic strain. Neither active nor passive immunization with FbsA or FbsA-specific antibodies, respectively, resulted in any protection against subsequent infection with the S. agalactiae wt strain. CONCLUSION: Our results clearly indicate that the expression of FbsA by Streptococcus agalactiae is a significant virulence determinant in septic arthritis and septicemia. However, because blocking of the fibrinogen binding properties did not protect the host against the action of FbsA-expressing streptococci, we believe that the FbsA molecule has some other presently unknown biological in vivo properties.
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| 24. |
- Jonsson, Ing-Marie, 1949, et al.
(författare)
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Sigma factor B and RsbU are required for virulence in Staphylococcus aureus-induced arthritis and sepsis
- 2004
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Ingår i: Infect Immun. - 0019-9567. ; 72:10, s. 6106-11
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Tidskriftsartikel (refereegranskat)abstract
- The prototype Staphylococcus aureus strain 8325-4 produces high levels of hemolysins and proteases. Recently it has been shown that this property depends on a deficiency of sigma factor B (SigB) activity controlling the activation of regulatory genes such as agr and sarA. SigB deficiency is in turn due to a mutation in the rsbU gene, which is required for posttranslational activation of SigB. The rsbU defect of strain 8325-4 has recently been repaired, and we used this strain (SH1000), along with its isogenic sigB-negative mutant, to investigate the contributions of RsbU and SigB in a murine model of septic arthritis. Intravenous inoculation with the rsbU-repaired isogenic strain SH1000 resulted in significantly more severe arthritis, weight decrease, and mortality compared to those of the parental strain 8325-4 (rsbU-negative) or the isogenic sigB-negative mutant (MJH502). SH1000 also persisted more in kidneys and joints of infected mice. Our data strongly suggest that RsbU and SigB regulate important virulence factors, thereby contributing significantly to the outcome of staphylococcal infection.
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| 25. |
- Kenny, John G, et al.
(författare)
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The Staphylococcus aureus response to unsaturated long chain free fatty acids: survival mechanisms and virulence implications.
- 2009
-
Ingår i: PLoS ONE. ; 4:2
-
Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is an important human commensal and opportunistic pathogen responsible for a wide range of infections. Long chain unsaturated free fatty acids represent a barrier to colonisation and infection by S. aureus and act as an antimicrobial component of the innate immune system where they are found on epithelial surfaces and in abscesses. Despite many contradictory reports, the precise anti-staphylococcal mode of action of free fatty acids remains undetermined. In this study, transcriptional (microarrays and qRT-PCR) and translational (proteomics) analyses were applied to ascertain the response of S. aureus to a range of free fatty acids. An increase in expression of the sigma(B) and CtsR stress response regulons was observed. This included increased expression of genes associated with staphyloxanthin synthesis, which has been linked to membrane stabilisation. Similarly, up-regulation of genes involved in capsule formation was recorded as were significant changes in the expression of genes associated with peptidoglycan synthesis and regulation. Overall, alterations were recorded predominantly in pathways involved in cellular energetics. In addition, sensitivity to linoleic acid of a range of defined (sigB, arcA, sasF, sarA, agr, crtM) and transposon-derived mutants (vraE, SAR2632) was determined. Taken together, these data indicate a common mode of action for long chain unsaturated fatty acids that involves disruption of the cell membrane, leading to interference with energy production within the bacterial cell. Contrary to data reported for other strains, the clinically important EMRSA-16 strain MRSA252 used in this study showed an increase in expression of the important virulence regulator RNAIII following all of the treatment conditions tested. An adaptive response by S. aureus of reducing cell surface hydrophobicity was also observed. Two fatty acid sensitive mutants created during this study were also shown to diplay altered pathogenesis as assessed by a murine arthritis model. Differences in the prevalence and clinical importance of S. aureus strains might partly be explained by their responses to antimicrobial fatty acids.
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| 26. |
- Khan, Omar M., 1980, et al.
(författare)
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Geranylgeranyltransferase type I (GGTase-I) deficiency hyperactivates macrophages and induces erosive arthritis in mice.
- 2011
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Ingår i: The Journal of clinical investigation. - 1558-8238. ; 121:2, s. 628-39
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Tidskriftsartikel (refereegranskat)abstract
- RHO family proteins are important for the function of inflammatory cells. They are modified with a 20-carbon geranylgeranyl lipid in a process catalyzed by protein geranylgeranyltransferase type I (GGTase-I). Geranylgeranylation is viewed as essential for the membrane targeting and activity of RHO proteins. Consequently, inhibiting GGTase-I to interfere with RHO protein activity has been proposed as a strategy to treat inflammatory disorders. However, here we show that mice lacking GGTase-I in macrophages develop severe joint inflammation resembling erosive rheumatoid arthritis. The disease was initiated by the GGTase-I-deficient macrophages and was transplantable and reversible in bone marrow transplantation experiments. The cells accumulated high levels of active GTP-bound RAC1, CDC42, and RHOA, and RAC1 remained associated with the plasma membrane. Moreover, GGTase-I deficiency activated p38 and NF-κB and increased the production of proinflammatory cytokines. The results challenge the view that geranylgeranylation is essential for the activity and localization of RHO family proteins and suggest that reduced geranylgeranylation in macrophages can initiate erosive arthritis.
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| 27. |
- Kirdis, Ebru, et al.
(författare)
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Ribonucleotide reductase class III, an essential enzyme for the anaerobic growth of Staphylococcus aureus, is a virulence determinant in septic arthritis
- 2007
-
Ingår i: Microb Pathog. - : Elsevier BV. - 0882-4010. ; 43, s. 171-188
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is the most common cause of joint infections. It also contributes to several other diseases such as pneumonia, osteomyelitis, endocarditis, and sepsis. Bearing in mind that S. aureus becomes rapidly resistant to new antibiotics, many studies survey the virulence factors, with the aim to find alternative prophylaxis/treatment regimens. One potential virulence factor is the bacterial ability to survive at different oxygen tensions. S. aureus expresses ribonucleotide reductases (RNRs), which help it to grow under both aerobic and anaerobic conditions, by reducing ribonucleotides to deoxyribonucleotides. In this study, we investigated the role of RNR class III, which is required for anaerobic growth, as a virulence determinant in the pathogenesis of staphylococcal arthritis. The wild-type S. aureus strain and its isogenic mutant nrdDG mutant were inoculated intravenously into mice. Mice inoculated with the wild-type strain displayed significantly more severe arthritis, with significantly more synovitis and destruction of the bone and cartilage versus mutant strain inoculated mice. Further, the persistence of bacteria in the kidneys was significantly more pronounced in the group inoculated with the wild-type strain. Together these results indicate that RNR class III is an important virulence factor for the establishment of septic arthritis.
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| 28. |
- Kłak, Marcin, et al.
(författare)
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Tranexamic acid, an inhibitor of plasminogen activation, aggravates staphylococcal septic arthritis and sepsis.
- 2010
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 1651-1980 .- 0036-5548. ; 42:5, s. 351-358
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Haemostatic balance shifts towards pro-coagulation during infection. Plasminogen, a key molecule of fibrinolysis, may play an important role in the pathogenesis of staphylococcal infections. In the present study, we assessed the impact of inhibition of plasminogen activation by tranexamic acid on the course of staphylococcal sepsis and septic arthritis in mice. We found significantly down-regulated plasmin activity and increased D-dimer levels in the blood from the mice with staphylococcal sepsis. Treatment with tranexamic acid significantly increased the severity and mortality of staphylococcal infection. In addition, tranexamic acid reduced the survival rate in a murine model for staphylococcal enterotoxin A-induced death. The aggravation of diseases by tranexamic acid was due neither to the pro-inflammatory cytokine network, nor to impairment of bacterial clearance. Modulation of fibrinolysis, either by supplement of fibrinolytic molecules (tissue plasminogen activator or plasmin) or by fibrinogen depletion, did not reduce the mortality of staphylococcal sepsis. In conclusion, we report that treatment with tranexamic acid led to distinct aggravation of staphylococcal septic arthritis and sepsis in mice, suggesting the clinical importance of fibrinolytic balance in staphylococcal infection.
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| 29. |
- Lindblad, Sofia S, et al.
(författare)
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The N-Methyl-D-Aspartic Acid Receptor Antagonist Memantine Ameliorates and Delays the Development of Arthritis by Enhancing Regulatory T Cells.
- 2012
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Ingår i: Neuro-Signals. - : S. Karger AG. - 1424-8638. ; 20:2, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- The neuroendocrine impact on rheumatoid arthritis is not yet fully described although numerous neurotransmitters are shown to act as inflammatory modulators. One of these is the excitatory transmitter glutamate (Glu). In this study, the influence of the Glu receptor (GluR)-mediated effects on collagen-induced arthritis (CIA) was investigated. CIA was induced in DBA/1 mice by immunization with chicken collagen type II (CII). Mice were exposed to the following GluR antagonists: group 1, the N-methyl-D-aspartic acid (NMDA) receptor channel blocker memantine; group 2, the metabotropic GluR antagonist AIDA, and group 3, the excitatory amino acid receptor antagonist kynurenic acid (KA). Arthritis was evaluated clinically and histologically and compared to PBS-treated controls. The effects of treatment on T cell populations and the levels of anti-CII and anti-citrullinated peptide antibodies were evaluated. Memantine treatment significantly improved the course of CIA, reducing synovitis (p = 0.007) and the frequency of erosions (p = 0.007). Memantine treatment up-regulated the expression of Foxp3 in spleen CD4+ T cells followed by an increase in CD4+CD25+ regulatory T cells. The other GluR antagonists, AIDA and KA, had no effect on CIA. These results demonstrate that blockade of the NMDA receptor channel with memantine delays and attenuates the development of arthritis, probably by promoting the development of regulatory T lymphocytes.
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| 30. |
- Pizzolla, A., et al.
(författare)
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Reactive Oxygen Species Produced by the NADPH Oxidase 2 Complex in Monocytes Protect Mice from Bacterial Infections
- 2012
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 188:10, s. 5003-5011
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Tidskriftsartikel (refereegranskat)abstract
- Chronic granulomatous disease (CGD) is an inherited disorder characterized by recurrent life-threatening bacterial and fungal infections. CGD results from defective production of reactive oxygen species by phagocytes caused by mutations in genes encoding the NADPH oxidase 2 (NOX2) complex subunits. Mice with a spontaneous mutation in Ncf1, which encodes the NCF1 (p47(Phox)) subunit of NOX2, have defective phagocyte NOX2 activity. These mice occasionally develop local spontaneous infections by Staphylococcus xylosus or by the common CGD pathogen Staphylococcus aureus. Ncf1 mutant mice were more susceptible to systemic challenge with these bacteria than were wild-type mice. Transgenic Ncf1 mutant mice harboring the wild-type Ncf1 gene under the human CD68 promoter (MN+ mice) gained the expression of NCF1 and functional NOX2 activity specifically in monocytes/macrophages, although minimal NOX2 activity was also detected in some CD11b(+)Ly6G(+) cells defined as neutrophils. MN+ mice did not develop spontaneous infection and were more resistant to administered staphylococcal infections compared with MN- mice. Most strikingly, MN+ mice survived after being administered Burkholderia cepacia, an opportunistic pathogen in CGD patients, whereas MN- mice died. Thus, monocyte/macrophage expression of functional NCF1 protected against spontaneous and administered bacterial infections. The Journal of Immunology, 2012, 188: 5003-5011.
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| 31. |
- Pullerits, Rille, 1969, et al.
(författare)
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Extracellular cytochrome c, a mitochondrial apoptosis-related protein, induces arthritis
- 2005
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Ingår i: Rheumatology (Oxford). - : Oxford University Press (OUP). - 1462-0324 .- 1462-0332. ; 44:1, s. 32-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The aim of the study was to assess the role of extracellular cytochrome c as an inducer of joint inflammation and to examine its levels in sera and synovial fluids of rheumatoid arthritis (RA) patients. METHODS: Mice were injected intra-articularly with different doses of cytochrome c and joints were evaluated histopathologically and immunohistochemically 3 and 10 days later. In addition, mouse spleen cells were stimulated with different concentrations of cytochrome c, followed by assessment of NF-kappaB activation and cytokine production. Sera and synovial fluid from RA patients and sera from healthy individuals were assessed with respect to cytochrome c levels by an enzyme-linked immunoassay technique. RESULTS: Histopathological signs of arthritis were evident in 75% of animals following intra-articular injection of cytochrome c. Synovitis was characterized by influx of Mac-1+ cells. In vivo depletion of neutrophils and monocytes led to abrogation of arthritis. Stimulation of mouse spleen cells in vitro with cytochrome c resulted in activation of NF-kappaB and release of proinflammatory cytokines and chemokines. Cytochrome c levels in RA patients' sera were significantly lower than in healthy controls. Further, cytochrome c levels in synovial fluid were significantly lower than in corresponding blood samples. CONCLUSIONS: Our findings demonstrate that extracellular cytochrome c displays direct proinflammatory properties mediated by activation of NF-kappaB and causing neutrophil and monocyte triggered inflammation. We hypothesize that decreased levels of cytochrome c in RA patients reflect consumption of this molecule in the synovial tissue, decreasing apoptosis and shifting the balance towards inflammation.
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| 32. |
- Pullerits, Rille, 1969, et al.
(författare)
-
High mobility group box chromosomal protein 1, a DNA binding cytokine, induces arthritis.
- 2003
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Ingår i: Arthritis and Rheumatism. - 1529-0131. ; 48:6, s. 1693-1700
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine the potential role of high mobility group box chromosomal protein 1 (HMGB-1) in the pathogenesis of arthritis. METHODS: Mice were injected intraarticularly with 1 microg or 5 microg of HMGB-1. Joints were dissected on days 4, 7, and 28 after injection and were evaluated histopathologically and immunohistochemically. To investigate the importance of different white blood cell populations for the development of arthritis, in vivo cell depletion procedures were performed. In addition, spleen cells were cultured in the presence of HMGB-1, and nuclear factor kappaB (NF-kappaB) activation was detected by electrophoretic mobility shift assay. RESULTS: Injection of recombinant HMGB-1 (rHMGB-1) into different mouse strains resulted in an overall frequency of arthritis in 80% of the animals. The inflammation was characterized by mild to moderate synovitis and lasted for at least 28 days. The majority of cells found in the inflamed synovium were Mac-1+ macrophages, whereas only a few CD4+ lymphocytes were detected. Pannus formation was observed in some cases 7 and 28 days after HMGB-1 injection. No significant differences were found with respect to incidence and severity of arthritis between mice depleted of monocytes, granulocytes, or lacking T/B lymphocytes. However, combined removal of monocytes and neutrophils resulted in a 43% lower incidence of arthritis. Mice rendered deficient in the interleukin-1 (IL-1) receptor did not develop inflammation upon challenge with HMGB-1. In vitro data corroborate this finding, showing that rHMGB-1 activated NF-kappaB, a major pathway leading to IL-1 production. CONCLUSION: Our results indicate that HMGB-1 is not a mere expression of inflammatory responses, but on its own, it triggers joint inflammation by activating macrophages and inducing production of IL-1 via NF-kappaB activation.
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| 33. |
- Pullerits, Rille, 1969, et al.
(författare)
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Induction of arthritis by high mobility group box-1 protein is independent of tumour necrosis factor signalling.
- 2008
-
Ingår i: Arthritis research & therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: INTRODUCTION: TNFalpha and HMGB1 are two potent pro-inflammatory cytokines implicated as important mediators of arthritis. Increased levels of these cytokines are found in the joints of RA patients and they trigger arthritis when applied into the joints of naive mice. HMGB1 is actively released from immune cells in response to TNFalpha and once released, it induces in turn production of several pro-inflammatory cytokines including IL-6 and TNFalpha by macrophages. However, it is unknown whether HMGB1-induced arthritis is mediated via TNFalpha pathway. The purpose of this study was to investigate whether the arthritis-inducing effect of HMGB1 is dependent on TNFalpha expression in vivo and to assess whether TNFalpha deficiency affects a pro-inflammatory cytokine response to HMGB1 in vitro. METHODS: TNFalpha knockout (KO) mice and backcrossed control animals on C57Bl6 background were injected intra-articularly (i.a.) with 5 micrograms of HMGB1. Joints were dissected three days after i.a. injection and evaluated histologically by scoring the frequency and severity of arthritis. For in vitro studies, mouse spleen cultures from TNFalpha KO and control mice were incubated with different doses of HMGB1and cell culture supernatants were collected at different time points for analysis of IL-6. RESULTS: I.a. injection of HMGB1 into healthy mouse joints resulted in overall frequency of 32-39 % arthritic animals. No significant differences were found with respect to severity and incidence of synovitis between mice deficient for TNFalpha (7 out of 18 mice with arthritis) in comparison with control TNFalpha+/+ animals (6 out of 19). No significant differences were detected between spleen cells from TNFalpha+/+ versus TNFalpha-/- mice regarding IL-6 production upon stimulation with highly purified HMGB1 following 24 and 48 hours. However, upon stimulation with suboptimal dose of recombinant HMGB1, the splenocytes from TNFalpha+/+ animals released significantly more IL-6 than cells from the knockout mice (602 +/- 112 and 304 +/- 50 pg/ml, respectively, p< 0.05). CONCLUSIONS: Our data show that HMGB1 triggered joint inflammation is not mediated via TNF pathway. Combined with our previous study, we suggest that HMBG1-triggered arthritis is likely to be mediated through IL-1 activation.
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| 34. |
- Pullerits, Rille, 1969, et al.
(författare)
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Soluble receptor for advanced glycation end products triggers a proinflammatory cytokine cascade via beta2 integrin Mac-1
- 2006
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Ingår i: Arthritis Rheum. - : Wiley. - 0004-3591. ; 54:12, s. 3898-907
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Receptor for advanced glycation end products (RAGE) is a cell surface molecule that binds a variety of ligands, including high mobility group box chromosomal protein 1 (HMGB-1), a potent proinflammatory cytokine. RAGE-ligand interaction leads to an inflammatory response. A truncated form of the receptor, soluble RAGE (sRAGE), has been suggested to function as a decoy abrogating cellular activation, but its endogenous activity is not fully understood. We undertook this study to assess the properties of sRAGE in vivo and in vitro and to analyze the role of sRAGE in HMGB-1-induced arthritis. METHODS: Mice were injected intraarticularly with HMGB-1 and treated systemically with sRAGE prior to histologic joint evaluation. All animals were subjected to peritoneal lavage to assess the local effect of sRAGE treatment. For in vitro studies, mouse splenocytes were incubated with sRAGE followed by assessment of NF-kappaB activation and cytokine production. The chemotactic properties of sRAGE were investigated using in vitro migration assay. RESULTS: Soluble RAGE was determined to have proinflammatory properties since it gave rise to production of interleukin-6, tumor necrosis factor alpha, and macrophage inflammatory protein 2. This effect was triggered by interaction with leukocyte beta2 integrin Mac-1 and was mediated via NF-kappaB. Systemic treatment with sRAGE significantly down-regulated HMGB-1-triggered arthritis, but the observed effect was due to a deviation of the inflammatory response from the joint to the peritoneal cavity rather than a genuine antiinflammatory effect. Apart from its proinflammatory properties, sRAGE was proven to act as a chemotactic stimulus for neutrophils. CONCLUSION: We conclude that sRAGE interacts with Mac-1, thereby acting as an important proinflammatory and chemotactic molecule.
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| 35. |
- Sabala, I., et al.
(författare)
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Anti-staphylococcal activities of lysostaphin and LytM catalytic domain
- 2012
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lysostaphin and the catalytic domain of LytM cleave pentaglycine crossbridges of Staphylococcus aureus peptidoglycan. The bacteriocin lysostaphin is secreted by Staphylococcus simulans biovar staphylolyticus and directed against the cell walls of competing S. aureus. LytM is produced by S. aureus as a latent autolysin and can be activated in vitro by the removal of an N-terminal domain and occluding region. Results: We compared the efficacies of the lysostaphin and LytM catalytic domains using a newly developed model of chronic S. aureus infected eczema. Lysostaphin was effective, like in other models. In contrast, LytM was not significantly better than control. The different treatment outcomes could be correlated with in vitro properties of the proteins, including proteolytic stability, affinity to cell wall components other than peptidoglycan, and sensitivity to the ionic milieu. Conclusions: Although lysostaphin and LytM cleave the same peptide bond in the peptidoglycan, the two enzymes have very different environmental requirements what is reflected in their contrasting performance in mouse eczema model.
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| 36. |
- Shaw, L. N., et al.
(författare)
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Inactivation of traP has no effect on the Agr quorum sensing system or virulence of Staphylococcus aureus
- 2007
-
Ingår i: Infection and immunity. - 0019-9567. ; 75
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Tidskriftsartikel (refereegranskat)abstract
- The success of S. aureus as a pathogen can largely be ascribed to the plethora of genetic regulators encoded within its genome that temporally regulate its arsenal of virulence determinants throughout its virulence lifestyle. Arguably the most important of these is the two-component, quorum-sensing system agr. Over the last decade the controversial presence of a second quorum-sensing system has been proposed (the TRAP system), and has been mooted to function as the master regulator of virulence in S. aureus by modulating agr. Mutants defective in TRAP are reported to be devoid of agr expression, lacking in hemolytic activity, essentially deficient in the secretion of virulence determinants, and avirulent in infection models. A number of research groups have questioned the validity of the TRAP findings in recent years; however a thorough and independent analysis of its role in S. aureus physiology and pathogenesis has not been forthcoming. Therefore we have undertaken such an analysis of the TRAP locus of S. aureus. We found that a traP mutant was equally hemolytic as the wild-type strain. Furthermore transcriptional profiling found no alterations in the traP mutant in expression levels of agr, nor in the expression levels of multiple agr regulated genes (hla, sspA, spa). Analysis of secreted and surface proteins of the traP mutant revealed no deviation in comparison to the parent. Finally analysis conducted using a murine model of S. aureus septic arthritis revealed that, in contrast to an agr mutant, the traP mutant was just as virulent as the wild-type strain.
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| 37. |
- Silfverswärd Lindblad, Sofia, 1980, et al.
(författare)
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Smoking and nicotine exposure delay development of collagen-induced arthritis in mice.
- 2009
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Ingår i: Arthritis research & therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Recent epidemiologic studies have implicated smoking as an environmental risk factor for the development of rheumatoid arthritis (RA). The aim of the present study is the evaluation of the role of cigarette smoke (CS) in the pathogenesis of collagen-induced arthritis in mice. METHODS: DBA/1 mice exposed to CS for 16 weeks (n = 25) and mice exposed to nicotine in drinking water (n = 10) were immunized with collagen type II (CII). Severity of arthritis was evaluated clinically and morphologically and compared with control mice (n = 35). Intensity of inflammation was evaluated by serum IL-6 and TNF-alpha levels. Additionally, antibody response to CII (anti-CII) and citrullinated peptides (aCCP) was measured. RESULTS: Clinical evaluation of arthritis showed a delayed onset of arthritis in CS-exposed mice compared with non-smoking controls (P < 0.05). Histologic index and weight changes were comparable between the groups; however, smoking mice presented less weight loss during the acute phase of the disease and gained weight significantly faster in the recovery phase (P < 0.05). Similar results were obtained in the mice exposed to nicotine. Nicotine also showed a direct anti-inflammatory effect diminishing IL-6 production by stimulated splenocytes in vitro (P < 0.001). Additionally, smoking mice had lower levels of aCCP and anti-CII antibodies compared with non-smoking (P < 0.05). CONCLUSIONS: Neither smoking nor nicotine exposure aggravates development of CII-induced arthritis in mouse model. Moreover, CS exposure was associated with a lower level of anti-CII antibodies, providing a possible explanation for a delay of arthritis onset in this group.
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| 38. |
- Stapleton, M. R., et al.
(författare)
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Characterisation of IsaA and SceD, two putative lytic transglycosylases of Staphylococcus aureus
- 2007
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Ingår i: J Bacteriol. - 0021-9193. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial cell wall peptidoglycan is a dynamic structure requiring hydrolysis to allow cell wall growth and division. Staphylococcus aureus has many known and putative peptidoglycan hydrolases, including two likely lytic transglycosylases. These two proteins, IsaA and SceD, were both found to have autolytic activity. Regulatory studies showed that isaA and sceD genes are partially mutually compensatory, with the production of SceD being upregulated in an isaA mutant. The expression of sceD is also greatly upregulated by the presence of NaCl. Several regulators of isaA and sceD expression were identified. Inactivation of sceD resulted in impaired cell separation, as seen by light microscopy, and "clumping" of bacterial cultures. An isaA sceD mutant is attenuated for virulence, whilst SceD is essential for nasal colonisation in cotton rats, thus demonstrating the importance of cell wall dynamics in host-pathogen interactions.
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| 39. |
- Svensson, Mattias, 1982, et al.
(författare)
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Fms-like tyrosine kinase 3 ligand controls formation of regulatory T cells in autoimmune arthritis.
- 2013
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Fms-like tyrosine kinase 3 ligand (Flt3L) is known as the primary differentiation and survival factor for dendritic cells (DCs). Furthermore, Flt3L is involved in the homeostatic feedback loop between DCs and regulatory T cell (Treg). We have previously shown that Flt3L accumulates in the synovial fluid in rheumatoid arthritis (RA) and that local exposure to Flt3L aggravates arthritis in mice, suggesting a possible involvement in RA pathogenesis. In the present study we investigated the role of Flt3L on DC populations, Tregs as well as inflammatory responses in experimental antigen-induced arthritis. Arthritis was induced in mBSA-immunized mice by local knee injection of mBSA and Flt3L was provided by daily intraperitoneal injections. Flow cytometry analysis of spleen and lymph nodes revealed an increased formation of DCs and subsequently Tregs in mice treated with Flt3L. Flt3L-treatment was also associated with a reduced production of mBSA specific antibodies and reduced levels of the pro-inflammatory cytokines IL-6 and TNF-α. Morphological evaluation of mBSA injected joints revealed reduced joint destruction in Flt3L treated mice. The role of DCs in mBSA arthritis was further challenged in an adoptive transfer experiment. Transfer of DCs in combination with T-cells from mBSA immunized mice, predisposed naïve recipients for arthritis and production of mBSA specific antibodies. We provide experimental evidence that Flt3L has potent immunoregulatory properties. Flt3L facilitates formation of Treg cells and by this mechanism reduces severity of antigen-induced arthritis in mice. We suggest that high systemic levels of Flt3L have potential to modulate autoreactivity and autoimmunity.
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| 40. |
- Svensson, Mattias, 1982, et al.
(författare)
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Impaired signaling through the Fms-like tyrosine kinase 3 receptor increases osteoclast formation and bone damage in arthritis.
- 2016
-
Ingår i: Journal of leukocyte biology. - 1938-3673. ; 99:3, s. 413-423
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Tidskriftsartikel (refereegranskat)abstract
- Osteoclasts are bone-resorbing cells that accumulate in the joints of patients with rheumatoid arthritis causing severe bone damage. Fms-like tyrosine kinase 3 ligand is enriched in the synovial fluid of patients with rheumatoid arthritis, and local exposure to Fms-like tyrosine kinase 3 ligand aggravates arthritis in mice. Because Fms-like tyrosine kinase 3 ligand has been suggested to facilitate osteoclast differentiation, we asked whether Fms-like tyrosine kinase 3 ligand affects bone remodeling in arthritis. The effect of Fms-like tyrosine kinase 3 signaling on osteoclast development was studied by immunohistochemistry in methylated bovine serum albumin-induced arthritis using mice that lack the gene for Flt3l (Flt3L(-/-)) and by an in vitro assay. Bone and joint changes were studied morphologically and by microcomputer tomography. We found that Flt3L(-/-) mice had increased accumulations of osteoclasts in the periarticular area of the arthritic joint. This triggered bone destruction and trabecular bone loss. The increased number of osteoclasts in Flt3L(-/-) mice may be a consequence of insufficient expression of interferon regulatory factor 8. Treatment of Flt3L(-/-) mice with Fms-like tyrosine kinase 3 ligand increased expression of interferon regulatory factor 8, reduced the number of osteoclasts in arthritic mice, and promoted trabecular bone formation. Finally, the reduced number of regulatory T cells in the bone marrow of Flt3L(-/-) mice could further contribute to the increased osteoclastogenesis by reducing the ratio of regulatory T cells to T helper 17 cells. This study shows that Fms-like tyrosine kinase 3 ligand may serve as a negative regulator of osteoclast development by promoting transcription of interferon regulatory factor 8 and sustaining a balance between protective regulatory T cells and pathogenic T helper 17 cells in the pathogenesis of arthritis.
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| 41. |
- Svensson, Mattias, 1982, et al.
(författare)
-
Murine germinal center B cells require functional Fms-like tyrosine kinase 3 signaling for IgG1 class-switch recombination.
- 2015
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 112:48
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Tidskriftsartikel (refereegranskat)abstract
- Switched antibody classes are important for efficient immune responses. Aberrant antibody production to otherwise harmless antigens may result in autoimmunity. The protein kinase fms-like tyrosine kinase 3 receptor (Flt3) has an important role during early B-cell development, but the role of Flt3 in peripheral B cells has not been assessed before. Herein we describe a previously unappreciated role for Flt3 in IgG1 class-switch recombination (CSR) and production. We show that Flt3 is reexpressed on B-cell lymphoma 6(+) germinal center B cells in vivo and following LPS activation of peripheral B cells in vitro. Absence of Flt3 signaling in Flt3 ligand-deficient mice results in impaired IgG1 CSR and accumulation of IgM-secreting plasma cells. On activated B cells, Flt3 is coexpressed and functions in synergy with the common-gamma chain receptor family. B cells from Flt3 ligand-deficient mice have impaired IL-4R signaling, with reduced phosphorylation of signal transducer and activator of transcription (Stat) 6, and demonstrate a failure to initiate CSR to IgG1 with low expression of γ1 germ-line transcripts, resulting in impaired IgG1 production. Thus, functional synergy between Flt3 and IL-4R signaling is critical for Stat-mediated regulation of sterile γ1 germ-line transcripts and CSR to IgG1.
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| 42. |
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| 43. |
- Tarkowski, Andrej, 1951, et al.
(författare)
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Current status of pathogenetic mechanisms in staphylococcal arthritis.
- 2002
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Ingår i: FEMS microbiology letters. - 0378-1097. ; 217:2, s. 125-32
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Forskningsöversikt (refereegranskat)abstract
- Interactions between staphylococci and the joint tissues of the host lead typically to rapidly progressing and highly destructive processes. Staphylococci possess a vast arsenal of components and products that contribute to the pathogenesis of joint infection. Occasionally these compounds have overlapping activities and act either in concert or alone. Host responsiveness to staphylococcal infection displays an even more complex pattern. Most of the cells and molecules that participate in the innate immune system protect the host against bacteria. However, the staphylococci have developed systems that counteract endogenous protective mechanisms. Interestingly, certain cells and molecules of the acquired immune system potentiate the severity of infection by triggering exaggerated responses to the staphylococcal danger signals. This review deals with the intricate host-bacterium interactions that occur during experimental septic arthritis, and outlines potential preventive and treatment modalities.
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| 44. |
- Wising, Catharina, 1973, et al.
(författare)
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The cytolethal distending toxin of Haemophilus ducreyi aggravates dermal lesions in a rabbit model of chancroid
- 2005
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Ingår i: Microbes Infect. - : Elsevier BV. - 1286-4579. ; 7:5-6, s. 867-74
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Tidskriftsartikel (refereegranskat)abstract
- Haemophilus ducreyi, the etiologic agent of the sexually transmitted disease chancroid, produces a cytolethal distending toxin (HdCDT) that inhibits cultured cell proliferation, leading to cell death. A rabbit model of dermal infection was used to investigate the roles of H. ducreyi bacteria and HdCDT in the development, clinical appearance, and persistence of infection. A non-toxin producing H. ducreyi strain, and for comparison purposes a non-capsulated Haemophilus influenzae strain, were inoculated intradermally, with and without co-administration of purified HdCDT. Co-administration of HdCDT resulted in significant aggravation of H. ducreyi-induced inflammatory lesions, and development of ulcers in rabbit skin. Less pronounced inflammatory lesions and lack of epithelial eruption were observed after inoculation with H. influenzae. Histopathological sections of the H. ducreyi-induced lesions, in both the presence and absence of HdCDT, showed dense infiltrates of the same type inflammatory cells, with the exception of a prominent endothelial cell proliferation noted in sections from lesions caused by H. ducreyi and toxin. Signs of chronic inflammation with involvement of T cells, macrophages, eosinophils, and granuloma formation were observed after H. ducreyi inoculation both with and without toxin. In conclusion, H. ducreyi causes a pronounced, chronic inflammation with involvement of T cells and macrophages, and in combination with HdCDT production of ulcers in the rabbit model. These pathogenic mechanisms may promote the development and persistence of chancroid ulcers.
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| 45. |
- Zdzalik, M., et al.
(författare)
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Prevalence of genes encoding extracellular proteases in Staphylococcus aureus - important targets triggering immune response in vivo
- 2012
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Ingår i: Fems Immunology and Medical Microbiology. - 0928-8244. ; 66:2, s. 220-229
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Tidskriftsartikel (refereegranskat)abstract
- Proteases of Staphylococcus aureus have long been considered to function as important virulence factors, although direct evidence of the role of particular enzymes remains incomplete and elusive. Here, we sought to provide a collective view of the prevalence of extracellular protease genes in genomes of commensal and pathogenic strains of S.aureus and their expression in the course of human and mouse infection. Data on V8 protease, staphopains A and B, aureolysin, and the recently described and poorly characterized group of six Spl proteases are provided. A phylogenetically diverse collection of 167 clinical isolates was analyzed, resulting in the comprehensive genetic survey of the prevalence of protease-encoding genes. No correlation between identified gene patterns with specific infections was established. Humoral response against the proteases of interest was examined in the sera derived from human patients and from a model mouse infection. The analysis suggests that at least some, if not all, tested proteases are expressed and secreted during the course of infection. Overall, the results presented in this study support the hypothesis that the secretory proteases as a group may contribute to the virulence of S.aureus.
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