| 1. |
- Bokarewa, Maria, 1963, et al.
(författare)
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Human alpha -defensins neutralize fibrinolytic activity exerted by staphylokinase
- 2004
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Ingår i: Thromb Haemost. - 0340-6245. ; 91:5, s. 991-9
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Tidskriftsartikel (refereegranskat)abstract
- Defensins, cationic peptides with bacteriolytic properties, are abundantly found at inflammation sites and in human coronary vessels. Vascular occlusive diseases, such as myocardial infarction, pulmonary embolism, and peripheral arterial occlusion are presently treated by thrombolytic intervention using staphylokinase, a plasminogen activator of bacterial origin. In this study we assessed a possible interaction between defensins and staphylokinase, both molecules being present in an acutely ill patient. Using an ELISA-based system, we found that staphylokinase and defensins displayed a strong and dose-dependent binding. In contrast, urokinase, another plasminogen activator of endogenous origin, displayed only minimal binding to defensins. Next, we proved that interaction between staphylokinase and defensins led to functional consequences resulting in a significant decrease (p<0.002) of plasminogen activation capacity upon complex formation. In contrast, urokinase retained most of its activity even in 10-fold molar excess of defensins. Finally, we found that staphylokinase-triggered lysis of fibrin was efficiently inhibited in the presence of defensins. To assess structural requirements for staphylokinase/defensin interaction, six staphylokinase mutant variants were studied. Inactivation pattern of the tested staphylokinase variants suggested a direct binding of defensins to serine protease-like domain of staphylokinase. In conclusion, we show complex formation between staphylokinase and alpha-defensins resulting in a significant reduction of fibrinolytic activity. This finding may have clinical implications, since fibrinolytic effects of staphylokinase may be downregulated at the site of vascular occlusion.
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| 2. |
- Bokarewa, Maria, 1963, et al.
(författare)
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Intraarticular release and accumulation of defensins and bactericidal/permeability-increasing protein in patients with rheumatoid arthritis.
- 2003
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Ingår i: The Journal of rheumatology. - 0315-162X. ; 30:8, s. 1719-24
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Defensins and bactericidal/permeability-increasing protein (BPI) are the components of the azurophilic granules of polymorphonuclear cells (PMNC) maintaining antimicrobial protection. Both these substances have been suggested to interact with the host immune system rather than merely kill invading pathogens. We assessed concentrations of BPI and a-defensins in synovial fluid (SF) and matching blood samples of patients with rheumatoid arthritis (RA). METHODS: Matching samples of SF and blood were collected from 67 patients with RA (aged 21-73 yrs) with acute joint effusion. Blood samples from 22 healthy individuals made up a control group. Concentrations of BPI and human neutrophil peptides (HNP 1-3) were measured by ELISA. The results were related to radiological signs of destructive arthritis, duration of the disease, and laboratory markers of inflammation. RESULTS: BPI and HNP concentrations in SF were 10-60 times higher than in matching blood samples (p < 0.0001). Strong correlations between BPI and HNP concentrations were found in both blood and SF. In SF, BPI and HNP concentrations correlated to white blood cell (WBC) count (p < 0.001), and were associated with erosive joint disease (p < 0.05). In contrast, WBC count, serum C-reactive protein, or rheumatoid factor were not significantly correlated to the BPI or HNP concentrations. Serum BPI concentrations were moderately but significantly increased in RA patients compared in blood to controls (p < 0.05). CONCLUSION: BPI and HNP are accumulated in the synovial cavity of patients with RA. Significant correlation between joint erosion and local occurrence of BPI and HNP suggests participation of these molecules in regulation of the destructive course of RA.
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| 3. |
- Carlsten, Hans, 1954, et al.
(författare)
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The impact of a new immunomodulator oxo-quinoline-3-carboxamide on the progression of experimental lupus
- 2004
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Ingår i: Int Immunopharmacol. - : Elsevier BV. - 1567-5769. ; 4:12, s. 1515-23
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Tidskriftsartikel (refereegranskat)abstract
- Autoimmune, lupus-prone MRL lpr/lpr mice were treated orally with oxo-quinoline-3-carboxamide (ABR-25757), a newly developed immunomodulator. Treatment was initiated in one set of experiment at the age of 10 weeks, before the onset of clinically apparent disease, and in another set at 15 weeks, after the development of established lupus disease. Beneficial therapeutic effects were obtained even when ABR-25757 was administered at the lowest dose tested (7.5 microg/mouse/week) to 15 weeks old mice with established lupus disease. The effects of ABR-25757 on longevity, as well as on development of glomerulonephritis were pronounced and comparable with those of LS-2616, a potent immunomodulator. Administration of ABR-25757 did not significantly alter T cell responses in vivo nor in vitro. In addition, it only marginally suppressed B cell responses measured as frequencies of immunoglobulin secreting cells. By the same token this compound did not affect overall leukocyte content in primary (bone marrow) or secondary (spleen) lymphoid tissues. In contrast, treatment with ABR-25757 up regulated expression of pro-inflammatory transcription factors NF-kappaB and AP-1. These results suggest (a) a potential therapeutic role of ABR-25757 in the treatment of experimental lupus and (b) that the effect of the treatment is mediated by immunodeviation rather than by immunosuppression.
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| 4. |
- Jin, Tao, 1973, et al.
(författare)
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Fatal outcome of bacteraemic patients caused by infection with staphylokinase-deficient Staphylococcus aureus strains.
- 2003
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Ingår i: Journal of medical microbiology. - 0022-2615. ; 52:Pt 10, s. 919-23
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Tidskriftsartikel (refereegranskat)abstract
- Staphylokinase (SAK) is a plasminogen-activator protein produced by Staphylococcus aureus. SAK production was evaluated in vitro in S. aureus isolates from the bloodstream of patients with lethal (n = 56) and non-lethal (n = 57) bacteraemia and from anterior nares of healthy subjects (n = 48). Most isolates (93/161) produced SAK, and 68 % of SAK-producing isolates expressed both surface-bound and secreted types of SAK. SAK production was significantly less common among isolates from patients with lethal bacteraemia (39 %) than isolates from patients with non-lethal bacteraemia (68 %) or nasal carriage isolates (67 %) (P < 0.01). After adjusting for infection with methicillin-resistant S. aureus and APACHE II score, patients infected with SAK-deficient isolates were 4.3 times more likely to have lethal bacteraemia than patients whose infecting isolate produced high levels of SAK (> or =5 microg ml(-1)), suggesting that in vitro SAK production was inversely associated with clinical outcome among patients with S. aureus bacteraemia. The high frequency of SAK production in nasal isolates and in cases with uncomplicated bacteraemia suggests that SAK may be one of the adaptive mechanisms of S. aureus symbiosis with the host.
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| 5. |
- Jin, Tao, 1973, et al.
(författare)
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Staphylococcus aureus resists human defensins by production of staphylokinase, a novel bacterial evasion mechanism
- 2004
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Ingår i: J Immunol. - 0022-1767. ; 172:2, s. 1169-76
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Tidskriftsartikel (refereegranskat)abstract
- Alpha-defensins are peptides secreted by polymorphonuclear cells and provide antimicrobial protection mediated by disruption of the integrity of bacterial cell walls. Staphylokinase is an exoprotein produced by Staphylococcus aureus, which activates host plasminogen. In this study, we analyzed the impact of interaction between alpha-defensins and staphylokinase on staphylococcal growth. We observed that staphylokinase induced extracellular release of alpha-defensins from polymorphonuclear cells. Moreover, a direct binding between alpha-defensins and staphylokinase was shown to result in a complex formation. The biological consequence of this interaction was an almost complete inhibition of the bactericidal effect of alpha-defensins. Notably, staphylokinase with blocked plasminogen binding site still retained its ability to neutralize the bactericidal effect of alpha-defensins. In contrast, a single mutation of a staphylokinase molecule at position 74, substituting lysine for alanine, resulted in a 50% reduction of its alpha-defensin-neutralizing properties. The bactericidal properties of alpha-defensins were tested in 19 S. aureus strains in vitro and in a murine model of S. aureus arthritis. Staphylococcal strains producing staphylokinase were protected against the bactericidal effect of alpha-defensins. When staphylokinase was added to staphylokinase-negative S. aureus cultures, it almost totally abrogated the effect of alpha-defensins. Finally, human neutrophil peptide 2 injected intra-articularly along with bacteria alleviated joint destruction. In this study, we report a new property of staphylokinase, its ability to induce secretion of defensins, to complex bind them and to neutralize their bactericidal effect. Staphylokinase production may therefore be responsible in vivo for defensin resistance during S. aureus infections.
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| 6. |
- Jin, Tao, 1973, et al.
(författare)
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Urokinase, a constitutive component of the inflamed synovial fluid, induces arthritis.
- 2003
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Ingår i: Arthritis research & therapy. - 1478-6362. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Urokinase plasminogen activator (uPA) is an important regulator of fibrinolysis in synovial fluid. An increase of uPA activity and expression of its receptor have been reported in joints of patients with rheumatoid arthritis (RA). The aim of the present study was to assess the arthritogenic capacity of uPA and the mechanisms by which this effect is mediated. uPA was injected into the knee joints of healthy mice, and morphological signs of arthritis were assessed 4 days after the injection. The prerequisite of different leukocyte populations for the development of uPA-triggered arthritis was assessed by selective cell depletion. The inflammatory capacity of uPA was assessed in vitro. Finally, levels of uPA were measured in 67 paired blood and synovial fluid samples from RA patients. The synovial fluid from RA patients displayed higher levels of uPA compared with blood samples. Morphological signs of arthritis were found in 72% of uPA-injected joints compared with in only 18% of joints injected with PBS (P < 0.05). Synovitis was characterised by infiltration of CD4-Mac-1+ mononuclear cells, by the formation of pannus and by occasional cartilage destruction. The absence of monocytes and lymphocytes diminished the frequency of synovitis (P < 0.01), indicating an arthritogenic role of both these leukocyte populations. Synthetic uPA inhibitor downregulated the incidence of uPA-triggered arthritis by 50%. uPA induced arthritis, stimulating the release of proinflammatory cytokines IL-6, IL-1beta and tumour necrosis factor alpha. Accumulation of uPA locally in the joint cavity is a typical finding in erosive RA. uPA exerts potent arthritogenic properties and thus may be viewed as one of the essential mediators of joint inflammation.
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| 7. |
- Pullerits, Rille, 1969, et al.
(författare)
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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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| 8. |
- 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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| 9. |
- Zare, Fariba, 1972, et al.
(författare)
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Arthritogenic properties of double-stranded (viral) RNA
- 2004
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Ingår i: J Immunol. - 0022-1767. ; 172:9, s. 5656-63
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Tidskriftsartikel (refereegranskat)abstract
- Viral infections often lead to arthralgias and overt arthritic states. The inflammatogenic compound of the viruses giving rise to such an outcome has to date not been identified. Because expression of dsRNA is a common feature of all viruses, we decided to analyze whether this property leads to the induction of arthritis. Histological signs of arthritis were evident already on day 3 following intra-articular administration of dsRNA. Arthritis was characterized by infiltration of macrophages into synovial tissue. It was not dependent on acquired immune responses because SCID mice also raised joint inflammation. NF-kappa B was activated upon in vitro exposure to dsRNA, indicating its role in the induction/progression of arthritis. Importantly, we found that dsRNA arthritis was triggered through IL-1R signaling because mice being deficient for this molecule were unable to develop joint inflammation. Although dsRNA is typically recognized by Toll-like receptor 3, Toll-like receptor 3 knockout mice developed arthritis, indicating that some other receptors are instrumental in the inducing of inflammation. Our results from in vitro experiments indicate that proinflammatory cytokines and chemokines stimulating monocyte influx were readily triggered in response to stimulation with dsRNA. These findings demonstrate that viral dsRNA is clearly arthritogenic. Importantly, macrophages and their products play an important role in the development of arthritis triggered by dsRNA.
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