| 1. |
- Johnson, Louis Banka, et al.
(författare)
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Radiation enteropathy and leucocyte-endothelial cell reactions in a refined small bowel model
- 2004
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Ingår i: BMC Surgery. - : Springer Science and Business Media LLC. - 1471-2482. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Leucocyte recruitment and inflammation are key features of high dose radiation-induced tissue injury. The inflammatory response in the gut may be more pronounced following radiotherapy due to its high bacterial load in comparison to the response in other organs. We designed a model to enable us to study the effects of radiation on leucocyte-endothelium interactions and on intestinal microflora in the murine ileum. This model enables us to study specifically the local effects of radiation therapy. METHOD: A midline laparotomy was performed in male C57/Bl6 mice and a five-centimetre segment of ileum is irradiated using the chamber. Leucocyte responses (rolling and adhesion) were then analysed in ileal venules 2 - 48 hours after high dose irradiation, made possible by an inverted approach using intravital fluorescence microscopy. Furthermore, intestinal microflora, myeloperoxidase (MPO) and cell histology were analysed. RESULTS: The highest and most reproducible increase in leucocyte rolling was exhibited 2 hours after high dose irradiation whereas leucocyte adhesion was greatest after 16 hours. Radiation reduced the intestinal microflora count compared to sham animals with a significant decrease in the aerobic count after 2 hours of radiation. Further, the total aerobic counts, Enterobacteriaceae and Lactobacillus decreased significantly after 16 hours. In the radiation groups, the bacterial count showed a progressive increase from 2 to 24 hours after radiation. CONCLUSION: This study presents a refinement of a previous method of examining mechanisms of radiation enteropathy, and a new approach at investigating radiation induced leucocyte responses in the ileal microcirculation. Radiation induced maximum leucocyte rolling at 2 hours and adhesion peaked at 16 hours. It also reduces the microflora count, which then starts to increase steadily afterwards. This model may be instrumental in developing strategies against pathological recruitment of leucocytes and changes in intestinal microflora in the small bowel after radiotherapy.
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| 2. |
- Klintman, Daniel, et al.
(författare)
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Important role of p-selectin for leukocyte recruitment, hepatocellular injury, and apoptosis in endotoxemic mice.
- 2004
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Ingår i: Clinical and Diagnostic Laboratory Immunology. - 1071-412X. ; 11:1, s. 56-62
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Tidskriftsartikel (refereegranskat)abstract
- Leukocyte recruitment in the liver includes a two-step procedure in which selectin-dependent leukocyte rolling is a prerequisite for subsequent CD18-dependent leukocyte firm adhesion in postsinusoidal venules. However, the roles of the individual selectins in leukocyte rolling and adhesion, hepatocellular injury, and apoptosis remain elusive. Therefore, we examined the pathophysiological role of P-, E-, and L-selectin in male C57BL/6 mice challenged with lipopolysaccharide (LPS) and D-galactosamine (Gal) by use of intravital microscopy of the liver microcirculation. In control animals, administration of LPS-Gal provoked reproducible hepatic damage, including marked increases of leukocyte recruitment, liver enzymes, and hepatocyte apoptosis and reduced sinusoidal perfusion. Interestingly, pretreatment with an anti-P-selectin antibody (RB40.34) markedly reduced leukocyte rolling and firm adhesion by 65 and 71%, respectively. Moreover, interference with P-selectin function significantly improved sinusoidal perfusion and reduced the increase in liver enzymes by 49 to 84% in endotoxemic mice. Moreover, the activity of caspase-3 and the number of apoptotic hepatocytes were significantly reduced by 55 and 54%, respectively, in RB40.34-treated animals. In contrast, administration of an anti-E-selectin antibody (10E9.6) and an anti-L-selectin antibody (Mel-14) did not protect against endotoxin-induced leukocyte responses or hepatic injury. In conclusion, our novel findings document a principal role of P-selectin in mediating leukocyte rolling, a precondition to the subsequent firm adhesion of leukocytes in liver injury. Furthermore, our novel data demonstrate that inhibition of P-selectin function reduces hepatocellular injury and apoptosis, suggesting a causal relationship between leukocyte recruitment on one hand and hepatocellular injury and apoptosis on the other hand. Based on these findings, it is suggested that P-selectin may be an important therapeutic target in endotoxin-induced liver injury.
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| 3. |
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| 4. |
- Li, Xiang, et al.
(författare)
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Critical role of CXC chemokines in endotoxemic liver injury in mice.
- 2004
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 75:3, s. 443-452
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Tidskriftsartikel (refereegranskat)abstract
- Tissue accumulation of leukocytes constitutes a rate-limiting step in endotoxin-induced tissue injury. Chemokines have the capacity to regulate leukocyte trafficking. However, the role of CXC chemokines, i.e., macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC), in leukocyte recruitment, microvascular perfusion failure, cellular injury, and apoptosis in the liver remains elusive. Herein, mice were challenged with lipopolysaccharide (LPS) in combination with D-galactosamine, and intravital microscopy of the liver microcirculation was conducted 6 h later. It was found that immunoneutralization of MIP-2 and KC did not reduce LPS-induced leukocyte rolling and adhesion in postsinusoidal venules. In contrast, pretreatment with monoclonal antibodies against MIP-2 and KC abolished (83% reduction) extravascular recruitment of leukocytes in the livers of endotoxemic mice. Notably, endotoxin challenge increased the expression of CXC chemokines, which was mainly confined to hepatocytes. Moreover, endotoxin-induced increases of liver enzymes and hepatocellular apoptosis were decreased by more than 82% and 68%, respectively, and sinusoidal perfusion was restored in mice passively immunized against MIP-2 and KC. In conclusion, this study indicates that intravascular accumulation of leukocytes in the liver is independent of CXC chemokines in endotoxemic mice. Instead, our novel data suggest that CXC chemokines are instrumental in regulating endotoxin-induced transmigration and extravascular tissue accumulation of leukocytes. Indeed, these findings demonstrate that interference with MIP-2 and KC functions protects against septic liver damage and may constitute a potential therapeutic strategy to control pathological inflammation in endotoxemia.
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| 5. |
- Li, Xiang, et al.
(författare)
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Interleukin-10 mediates the protective effect of Linomide by reducing CXC chemokine production in endotoxin-induced liver injury
- 2004
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 143:7, s. 865-871
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Tidskriftsartikel (refereegranskat)abstract
- 1 The immunomodulator Linomide has been shown to protect against septic liver injury by reducing hepatic accumulation of leukocytes although the detailed anti-inflammatory mechanisms remain elusive. This study examined the effect of Linomide on the production of CXC chemokines, including macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC) and interleukin-10 (IL-10) in lipopolysaccharide (LPS)/D-galactosamine (Gal)-induced liver injury in mice. 2 It was found that pretreatment with 300 mg kg(-1) of Linomide markedly Suppressed leukocyte recruitment, perfusion failure, and hepatocellular damage and apoptosis in the liver of endotoxemic mice. 3 Administration of Linomide inhibited endotoxin-induced gene expression of MIP-2 and KC and significantly reduced the hepatic production of MIP-2 and KC by 63 and 80%, respectively. Moreover, it was found that Linomide increased the liver content of IL-10 by more than three-fold in endotoxemic mice. 4 The protective effect of Linomide against endotoxin-induced inflammation and liver injury was abolished in IL-10-deficient mice, suggesting that the beneficial effect of Linomide is dependent on the function of IL-10. 5 Taken together, these novel findings suggest that the protective effect of Linomide is mediated via local upregulation of IL-10, which in turn decreases the generation of CXC chemokines and pathological recruitment of leukocytes in the liver of endotoxemic mice.
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| 6. |
- Li, Xiang, et al.
(författare)
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Lymphocyte function antigen-1 mediates leukocyte adhesion and subsequent liver damage in endotoxemic mice
- 2004
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 141:4, s. 709-716
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Tidskriftsartikel (refereegranskat)abstract
- 1 Sepsis is associated with leukocyte activation and recruitment in the liver. We investigated the role of lymphocyte function antigen-1 (LFA-1) in endotoxin-induced leukocyte-endothelium interactions, microvascular perfusion failure, hepatocellular injury and apoptosis in the liver by use of gene-targeted mice, blocking antibodies and a synthetic inhibitor of LFA-1 (LFA703). For this purpose, mice were challenged with lipopolysaccharide (LPS)+D-galactosamine (Gal), and intravital microscopy of the liver microcirculation was conducted 6 h later. 2 The number of Firmly adherent leukocytes in response to LPS/Gal was reduced by 48% in LFA-1-deficient mice. Moreover, endotoxin-induced increases of apoptosis and enzyme markers of hepatocellular injury were decreased by 64 and 69-90%, respectively, in LFA-1-deficient mice. Furthermore, sinusoidal perfusion was improved in endotoxemic mice lacking LFA-1. 3 A similar protective pattern was observed in endotoxemic mice pretreated with an antibody against LFA-1. Thus, immunoneutralization of LFA-1 reduced endotoxin-induced leukocyte adhesion by 55%, liver enzymes by 64-66% and apoptosis by 42%, in addition to the preservation of microvascular perfusion. 4 Administration of a novel statin-derived inhibitor of LFA-1, LFA703, significantly decreased leukocyte adhesion (more than 56%) and the subsequent liver injury in endotoxemic mice. 5 Thus, this study demonstrates a pivotal role of LFA-1 in supporting leukocyte adhesion in the liver. Moreover, interference with LFA-1-mediated leukocyte adhesion protects against endotoxemic liver damage, and may constitute a potential therapeutic strategy in sepsis.
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| 7. |
- Riaz, AA, et al.
(författare)
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Role of angiotensin II in ischemia/reperfusion-induced leukocyte-endothelium interactions in the colon
- 2004
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Ingår i: FASEB Journal. - : Wiley. - 1530-6860 .- 0892-6638. ; 18:3, s. 881-881
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the present study were to determine the effects and mechanisms of angiotensin II (Ang II) on leukocyte-endothelium interactions and the role of Ang II in a novel model of ischemia/reperfusion (I/R) in the mouse colon. Ang II dose-dependently increased leukocyte rolling and adhesion in colonic venules. Importantly, Ang II-induced leukocyte rolling was completely inhibited by immunoneutralization of P-selectin, and leukocyte adhesion was abolished in lymphocyte function antigen-1 (LFA-1)-deficient mice. The P-selectin-dependent rolling was found to be a precondition for the subsequent LFA-1-dependent leukocyte adhesion. Moreover, Ang II-induced leukocyte responses involved generation of reactive oxygen species and up-regulation of CXC chemokines. Notably, CXC chemokines, but not Ang II, stimulated leukocyte chemotaxis in vitro. I/R increased gene expression of angiotensin converting enzyme (ACE) in the colon and plasma concentrations of Ang II. Inhibition of ACE and the type 1 angiotensin (AT(1)) receptor significantly decreased the I/R-induced leukocyte adhesion. Taken together, these novel findings demonstrate that Ang II exerts potent pro-inflammatory effects in the colonic microcirculation and that inhibition of Ang II expression or function protects against I/R-induced leukocyte responses in the colon. Thus, it is suggested that Ang II is a major target to control pathological inflammation in the colon.
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| 8. |
- Schramm, R, et al.
(författare)
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Leukocyte adhesion in aorta and femoral artery in vivo is mediated by LFA-1
- 2004
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Ingår i: Inflammation Research. - : Springer Science and Business Media LLC. - 1420-908X .- 1023-3830. ; 53:10, s. 523-527
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Cytokine-induced recruitment of leukocytes is an early feature during arterial injury and atherosclerotic plaque formation. The aim of this study was to analyze the role of the beta(2)-integrin lymphocyte function-associated antigen-1 (LFA- 1; CD11a/CD18) in cytokine-triggered firm leukocyte adhesion to arterial endothelium in vivo. Material and Methods: Intravital fluorescence microscopy was used to study leukocyte firm adhesion in the mouse aorta and femoral artery in response to combined local challenge with TNF-alpha and IL-1beta. Results: In wild-type (WT) mice, cytokine stimulation resulted in firm adhesion of 14.6 +/- 2.8 and 11.3 +/- 1.3 leukocytes/mm along the endothelium in the aorta and femoral artery (P < 0.05 vs. PBS-treated controls, n = 5-6). Notably, the number of firmly adherent leukocytes in aorta and femoral artery of cytokine-stimulated LFA-1-deficient animals was reduced by 54% and 92% indicating an important role of LFA-1 in leukocyte adhesion to arterial endothelium (P < 0.05 vs. controls, n = 5-6). In addition, pretreatment of WT mice with a monoclonal antibody (mAb) directed against murine LFA-1 attenuated the leukocyte adhesive response by 60% and 86% in aorta and femoral artery, respectively (P < 0.05 vs. control mAb-treated WT, n = 5-12). Conclusion: These novel data demonstrate that cytokine-induced firm leukocyte adhesion in the mouse aorta and femoral artery is LFA-1-dependent in vivo, which may implicate an important role for this β(2)-integrin leukocyte extravasation. in arterial injury and atherogenesis.
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| 9. |
- Schramm, R, et al.
(författare)
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Neutrophil recruitment in mast cell-dependent inflammation: inhibitory mechanisms of glucocorticoids
- 2004
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Ingår i: Inflammation Research. - : Springer Science and Business Media LLC. - 1420-908X .- 1023-3830. ; 53:12, s. 644-652
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Forskningsöversikt (refereegranskat)abstract
- Mast cells are strategically localized along the microvasculature in tissues in close contact with the external environment, such as the skin, lung and intestines. By releasing a multi-faceted spectrum of proinflammatory mediators, such as cytokines and chemokines, mast cells have the capacity to coordinate trafficking of leukocytes. Mast cells play a pathophysiological role in numerous inflammatory diseases as diverse as hypersensitivity reactions, ischemia/reperfusion injury and rheumatoid arthritis. On the other hand, mast cells act also as tissue sentinels and are critically involved in the host defensive response against microbial infection by stimulating neutrophil recruitment. Glucocorticoids are powerful agents frequently used in mast cell-dependent diseases, although the anti-inflammatory mechanisms of these compounds are not completely understood at present. In order to circumvent steroid-associated side-effects and develop more specific therapeutics, numerous studies have examined the mechanisms underlying glucocorticoid inhibition of mast cell-dependent neutrophil recruitment. Based on recent findings, it may be suggested that glucocorticoids selectively inhibit the expression and function of certain adhesion molecules and chemokines. This review summarizes current insights into the underlying mechanisms of mast cell-regulated tissue accumulation of neutrophils and the inhibitory effects of glucocorticoids.
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| 10. |
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