| 1. |
- Cedergren, Jan, et al.
(författare)
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Inducible nitric oxide synthase is expressed in synovial fluid granulocytes
- 2002
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Ingår i: Clinical Experimental Immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 130, s. 150-155
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to evaluate the NO-producing potential of synovial fluid (SF) cells. SF from 15 patients with arthritis was compared with blood from the same individuals and with blood from 10 healthy controls. Cellular expression of inducible nitric oxide synthase (iNOS) was analysed by flow cytometry. High-performance liquid chromatography was used to measure L-arginine and L-citrulline. Nitrite and nitrate were measured colourimetrically utilizing the Griess' reaction. Compared to whole blood granulocytes in patients with chronic arthritis, a prominent iNOS expression was observed in SF granulocytes (P < 0.001). A slight, but statistically significant, increase in iNOS expression was also recorded in lymphocytes and monocytes from SF. L-arginine was elevated in SF compared to serum (257 ± 78 versus 176 ± 65 µmol/l, P = 0.008), whereas a slight increase in L-citrulline (33 ± 11 versus 26 ± 9 µmol/l), did not reach statistical significance. Great variations but no significant differences were observed comparing serum and SF levels of nitrite and nitrate, respectively, although the sum of nitrite and nitrate tended to be elevated in SF (19.2 ± 20.7 versus 8,6 ± 6.5 µmol/l,P = 0.054). Synovial fluid leucocytes, in particular granulocytes, express iNOS and may thus contribute to intra-articular NO production in arthritis.
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| 2. |
- Cedergren, Jan, et al.
(författare)
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Inducible nitric oxide synthase (NOS II) is constitutive in human neutrophils
- 2003
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Ingår i: APMIS. - : Wiley. - 0903-4641 .- 1600-0463. ; 111:10, s. 963-968
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Tidskriftsartikel (refereegranskat)abstract
- The objective was to study the expression of inducible nitric oxide synthase (NOS II) in and NO production by human blood neutrophils and in in vivo exudated neutrophils. Cellular expression of NOS II was evaluated by flow cytometry in whole blood, in isolated blood neutrophils, and in neutrophils obtained by exudation in vivo into skin chambers. Neutrophil NOS II was also demonstrated by Western blotting. Uptake of 3H-labelled L-arginine was studied in vitro and NOS activity measured in a whole cell assay by the conversion of 3H-arginine to 3H-citrulline. In contrast to unseparated blood cells, NOS II was demonstrable both in isolated blood neutrophils and exudated cells. The failure to detect NOS II by flow cytometry in whole blood cells thus proved to be due to the quenching effect of hemoglobin. Western blotting revealed a 130 kD band corresponding to NOS II in isolated blood neutrophils, but detection was dependent on diisopropylfluorophosphate for proteinase inhibition. L-arginine was taken up by neutrophils, but enzymatic activity could not be demonstrated. We conclude that human neutrophils constitutively express NOS II, but that its demonstration by FITC-labelling is inhibited by hemoglobin-mediated quenching in whole blood samples.
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| 3. |
- Cedergren, Jan, et al.
(författare)
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Intracellular oxidative activation in synovial fluid neutrophils from patients with rheumatoid arthritis but not from other arthritis patients
- 2007
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 34:11, s. 2162-2170
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare total and intracellular oxidative activation of blood and synovial fluid (SF) neutrophils from patients with rheumatoid arthritis (RA) and other arthritides with blood donor neutrophils. Methods: Peripheral blood and SF samples were obtained from 26 gonarthritis patients (13 RA, 13 non-RA) attending the rheumatology unit for therapeutic joint aspiration. Isolated neutrophils were stimulated by a formylated tripeptide (fMLF) or by microbeads coated with collagen-I. Formation of superoxide-anion-derived reactive oxygen species (ROS) was studied by luminol-enhanced chemiluminescence. Paired samples of blood and SF neutrophils from patients with active arthritis were compared with blood neutrophils from patients in remission and from 47 healthy blood donors. Results: SF neutrophils from patients with RA, but not from non-RA patients, showed high baseline intracellular ROS production. Blood neutrophils from arthritis patients in remission existed in a primed state as revealed by more rapid oxidative response after collagen-bead challenge and a more pronounced response after fMLF stimulation compared to healthy blood donors. Blood neutrophils from RA patients with ongoing gonarthritis, however, did not differ from healthy blood donors concerning oxidative activation, whereas blood neutrophils from non-RA patients with gonarthritis showed a significantly lower peak ROS production. Conclusions: A novel finding with pathogenetic implications in our study is that SF neutrophils from patients with RA, but not other arthritides, are activated and produce ROS intracellularly. This implies that synovial neutrophils in RA are engaged in the processing of endocytosed material.
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| 4. |
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| 5. |
- Cedergren, Jan, 1965-
(författare)
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Radical aspects on arthritis : the role of neutrophil generation of nitric oxide and superoxide in inflammatory conditions
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The polymorphonuclear neutrophil granulocytes (neutrophils) are gaining renewed interest regarding their involvement in chronic inflammatory disorders, including rheumatoid arthritis (RA). Besides phagocytic and destructive capabilities, neutrophils have regulatory roles, e.g. by influencing responses from dendritic cells and lymphocytes. Several animal models have revealed that neutrophils are crucial for the initiation and maintenance of chronic inflammatory diseases. Neutrophil function is highly dependent on their ability to produce superoxide, an oxygen radical which can be further metabolized to other free radicals. Whether or not neutrophils are capable of producing the oxygen radical nitric oxide (NO˙) has been a matter of debate.In this thesis it was shown that freshly isolated neutrophils from the joint cavity of patients with RA, but not from other arthritis patients, had ongoing intracellular production of superoxide, indicating the processing of ingested material.The finding that joint neutrophils, but seemingly not circulating cells, expressed the NO-inducing enzyme iNOS, led to a series of experiments aimed to elucidate where in the exudative process this enzyme could first be detected. We could finally, for the first time, present evidence that human neutrophils actually express iNOS constitutively. Our data also suggest that neutrophil iNOS may be membrane associated, thus differing from the cytosolic location in other cell types. Since NOS activity was not demonstrated in isolated cells, the notion that neutrophil iNOS is regulated primarily at the transcriptional level must be questioned. NO production from iNOS requires the presence of its substrate, L-arginine. To test the hypothesis that neutrophil arginase prevents neutrophil NO-production, we investigated whether arginase inhibition affects neutrophil NO-dependent oxidative function. Initial data revealed a difference in the effect of arginase inhibition comparing neutrophil stimulus with a soluble formylated tri-peptide (fMLF) and integrin-mediated stimulation with particle-bound collagen type-1. This led to the hypothesis that integrin-ligation on neutrophils induces extracellular liberation of arginase, which was confirmed both by measuring arginase and its enzyme activity. The findings in this thesis may be important not only regarding the role of neutrophils in chronic joint inflammation, but also as a link in the accelerated atherosclerosis observed in chronic inflammatory disorders, e.g. RA.
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| 6. |
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| 7. |
- Johansson, AG, et al.
(författare)
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IgG immune complex binding to and activation of liver cells. An in vitro study with IgG immune complexes, Kupffer cells, sinusoidal endothelial cells and hepatocytes
- 2000
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Ingår i: International Archives of Allergy and Immunology. - 1018-2438 .- 1423-0097. ; 121:4, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: The aim was to study IgG immune complex (IC) binding to isolated hepatocytes, Kupffer cells (KCs) and sinusoidal endothelial cells (SECs). Further, we wished to analyze the capacity of IgG ICs to induce release of reactive oxygen metabolites by the IC-binding liver cells. Methods: ICs were formed between 125I-tyramine-cellobiose-labelled dinitrophenyl-conjugated human serum albumin (125I-TC-DNP10HSA) and polyclonal rabbit IgG antibodies. Binding of ICs to different rat liver cells in suspension was studied at 4░C. Production of reactive oxygen metabolites was measured by luminol-enhanced chemiluminescence at 37░C. Results: IgG mediated binding of 125I-TC-DNP10HSA to both KCs and SECs, but not to hepatocytes. The binding showed saturation kinetics and was blocked by an excess of unlabelled IgG-ICs. IgG-ICs activated KCs, but not SECs, to a chemiluminescence response. Conclusions: Both KCs and SECs bind IgG-ICs in vitro, probably via Fc receptor interaction. IgG-ICs activate KCs to produce reactive oxygen metabolites. The binding of IgG-ICs to isolated hepatocytes is small.
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