| 1. |
- Asaduzzaman, Muhammad, et al.
(författare)
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Critical role of p38 mitogen-activated protein kinase signaling in septic lung injury.
- 2008
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Ingår i: Critical Care Medicine. - 1530-0293. ; 36:2, s. 482-488
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Leukocyte-mediated tissue damage is a key feature in septic lung injury, although the signaling mechanisms behind pulmonary recruitment of leukocytes remain elusive. The aim of the present study was to define the role of p38 mitogen-activated protein kinase (MAPK) signaling in septic lung injury. DESIGN: Prospective experimental study. SETTING: University hospital research unit. SUBJECTS: Male C57BL/6 mice. INTERVENTIONS: Pulmonary edema, bronchoalveolar infiltration of leukocytes, levels of myeloperoxidase, and CXC chemokines were determined 6 and 24 hrs after cecal ligation and puncture (CLP). The specific p38 MAPK inhibitors SB 239063 and SKF 86002 were given immediately before CLP induction. Phosphorylation and activity of p38 MAPK were determined by immunoprecipitation and Western blot. MEASUREMENTS AND MAIN RESULTS: CLP induced clear-cut pulmonary damage characterized by edema formation, leukocyte infiltration, and increased levels of CXC chemokines in the lung. Moreover, CLP increased phosphorylation and activity of p38 MAPK in the lung, which was markedly inhibited by SB 239063. Interestingly, inhibition of p38 MAPK signaling protected against CLP-induced lung damage and edema. Indeed, both SB 239063 and SKF 86002 decreased CLP-induced leukocyte recruitment in the bronchoalveolar space and formation of CXC chemokines in the lung. CONCLUSIONS: Our data demonstrate that p38 MAPK signaling constitutes a key role in regulating CXC chemokine production in septic lung injury and that inhibition of p38 MAPK activity abolishes pulmonary infiltration of leukocytes as well as lung edema. These novel findings suggest that targeting the p38 MAPK signaling pathway may pave the way for a new therapeutic strategy against lung injury in polymicrobial sepsis.
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| 2. |
- Asaduzzaman, Muhammad, et al.
(författare)
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LFA-1 AND MAC-1 MEDIATE PULMONARY RECRUITMENT OF NEUTROPHILS AND TISSUE DAMAGE IN ABDOMINAL SEPSIS.
- 2008
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Ingår i: Shock. - : Ovid Technologies (Wolters Kluwer Health). - 1540-0514 .- 1073-2322. ; 30, s. 254-259
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil-mediated lung damage is an insidious feature in septic patients, although the adhesive mechanisms behind pulmonary recruitment of neutrophils in polymicrobial sepsis remain elusive. The aim of the present study was to define the role of lymphocyte function-antigen 1 (LFA-1) and membrane-activated complex 1 (Mac-1) in septic lung injury. Pulmonary edema, bronchoalveolar infiltration of neutrophils, levels of myeloperoxidase, and CXC chemokines were determined after cecal ligation and puncture (CLP). Mice were treated with monoclonal antibodies directed against LFA-1 and Mac-1 before CLP induction. Cecal ligation and puncture induced clear-cut pulmonary damage characterized by edema formation, neutrophil infiltration, and increased levels of CXC chemokines in the lung. Notably, immunoneutralization of LFA-1 or Mac-1 decreased CLP-induced neutrophil recruitment in the bronchoalveolar space by more than 64%. Moreover, functional inhibition of LFA-1 and Mac-1 abolished CLP-induced lung damage and edema. However, formation of CXC chemokines in the lung was intact in mice pretreated with the anti-LFA-1 and anti-Mac-1 antibodies. Our data demonstrate that both LFA-1 and Mac-1 regulate pulmonary infiltration of neutrophils and lung edema associated with abdominal sepsis. Thus, these novel findings suggest that LFA-1 or Mac-1 may serve as targets to protect against lung injury in polymicrobial sepsis.
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| 3. |
- Laschke, Mattias W, et al.
(författare)
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Sepsis-associated cholestasis is critically dependent on P-selectin-dependent leukocyte recruitment in mice.
- 2007
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Ingår i: American Journal of Physiology: Gastrointestinal and Liver Physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 292, s. 1396-1402
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Tidskriftsartikel (refereegranskat)abstract
- Cholestasis is a major complication in sepsis although the underlying mechanisms remain elusive. The aim of this study was to evaluate the role of P-selectin and leukocyte recruitment in endotoxemia- associated cholestasis. C57BL/6 mice were challenged intraperitoneally with endotoxin ( 0.4 mg/ kg), and 6 h later the common bile duct was cannulated for determination of bile flow and biliary excretion of bromosulfophthalein. Mice were pretreated with an anti-P-selectin antibody or an isotype- matched control antibody. Leukocyte infiltration was determined by measuring hepatic levels of myeloperoxidase. Tumor necrosis factor-alpha and CXC chemokines in the liver was determined by ELISA. Liver damage was monitored by measuring serum levels of alanine aminotransferase and aspartate aminotransferase. Apoptosis was quantified morphologically by nuclear condensation and fragmentation using Hoechst 33342 staining. Endotoxin induced a significant inflammatory response with increased TNF-alpha and CXC chemokine concentrations, leukocyte infiltration, liver enzyme release, and apoptotic cell death. This response was associated with pronounced cholestasis indicated by a > 70% decrease of bile flow and biliary excretion of bromosulfophthalein. Immunoneutralization of P-selectin significantly attenuated endotoxin- induced leukocyte infiltration reflected by a > 60% reduction of hepatic myeloperoxidase levels. Interference with P-selectin decreased endotoxin- mediated hepatocellular apoptosis and necrosis, but did not affect hepatic levels of tumor necrosis factor-alpha and CXC chemokines. Of interest, inhibition of P- selectin restored bile flow and biliary excretion of bromosulfophthalein to normal levels in endotoxin- challenged animals. Our study demonstrates for the first time that P-selectin-mediated recruitment of leukocytes, but not the local production of proinflammatory mediators, is the primary cause of cholestasis in septic liver injury.
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| 4. |
- Mangell, Peter, et al.
(författare)
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Critical role of P-selectin-dependent leukocyte recruitment in endotoxin-induced intestinal barrier dysfunction in mice.
- 2007
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Ingår i: Inflammation Research. - : Springer Science and Business Media LLC. - 1420-908X .- 1023-3830. ; 56:5, s. 189-194
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To define the importance of leukocyte recruitment in endotoxin-induced gut permeability. Materials and methods: 31 male C57BL/6 mice were challenged with lipopolysaccharide (LPS). Ileal permeability was measured in Ussing chambers and leukocyte-endothelium interactions studied with intravital fluorescence microscopy after 18 h. Results: LPS caused a clear-cut increase in leukocyte accumulation and intestinal permeability. Immunoneutralisation of P-selectin not only reduced leukocyte recruitment significantly (54% reduction) but also abolished endotoxin-induced intestinal leakage. Intestinal levels of pro-inflammatory chemokines increased markedly in response to LPS but were not influenced by inhibition of P-selectin in vivo. Conclusion: The present study shows not only that endotoxin-induced leukocyte recruitment is mediated by P-selectin but also that sepsis-associated intestinal leakage in the gut is largely regulated by leukocyte accumulation. Thus, our novel data demonstrate a critical link between P-selectin-dependent leukocyte recruitment and gut barrier failure in endotoxemia.
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| 5. |
- Muhammad, Asad, et al.
(författare)
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P-Selectin and P-Selectin Glycoprotein Ligand 1 Mediate Rolling of Activated CD8+ T Cells in Inflamed Colonic Venules.
- 2009
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Ingår i: Journal of Investigative Medicine. - 1708-8267. ; 57:7, s. 765-768
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:: Activated T cells regulate inflammatory diseases in the intestinal tract; however, the adhesive mechanisms governing CD8 T-cell recruitment in the colon are not known. METHODS:: Herein, we used a graft-versus-host disease (GvHD) model to study CD8 T-cell rolling and adhesion in the large intestine by use of intravital fluorescence microscopy. Graft-versus-host disease was induced by transferring 50 x 10 allogeneic donor splenocytes from BDF1, B6, H-2b mice to recipient BDF1, H-2 mice. After 8 days, rhodamine-labeled CD8 T cells (4 x 10) from healthy and GvHD mice were injected into both healthy and GvHD recipient mice, and CD8 T-cell-endothelium interactions were studied in the colon. RESULTS:: Activated CD8 T cells from GvHD mice expressed higher levels of P-selectin ligand and decreased levels of L-selectin. Immunoneutralization of P-selectin and P-selectin glycoprotein ligand 1 reduced CD8 T-cell rolling and adhesion in inflamed colonic venules by more than 71%. Inhibition of E-selectin had no effect on GvHD-induced CD8 T-cell-endothelium interactions. CONCLUSIONS:: We conclude that P-selectin and P-selectin glycoprotein ligand 1 are dominating molecules in supporting adhesive interactions of CD8 T cells in inflamed colonic venules and may be useful targets to protect against pathological inflammation in the large bowel.
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| 6. |
- Röme, Andrada, et al.
(författare)
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Critical Role of P-Selectin and Lymphocyte Function Antigen-1 in Radiation-Induced Leukocyte-Endothelial Cell Interactions in the Colon.
- 2007
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Ingår i: Diseases of the Colon & Rectum. - : Ovid Technologies (Wolters Kluwer Health). - 0012-3706. ; 50:12, s. 2194-2202
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Radiation therapy is frequently used in treating different types of tumors, although associated with serious side effects, such as fibrosis and complicated diarrhea. This study was designed to define the adhesive mechanisms behind radiotherapy-induced leukocyte recruitment in the colon. Methods All mice, except control animals, were radiated with a single dose of 20 Gy. Mice were pretreated with an isotype-matched control antibody or a monoclonal antibody directed against P-selectin. In separate experiments, lymphocyte function antigen-1–deficient animals were used. Leukocyte rolling and firm adhesion were determined by use of inverted intravital fluorescence microscopy 16 hours after radiation. Results It was found that immunoneutralization of P-selectin reduced leukocyte rolling by 83 percent and adhesion by 87 percent in radiated mice. Moreover, radiation-induced leukocyte adhesion in LFA-1-deficient mice was decreased by 94 percent compared with wild-type animals. Conclusions This study demonstrates that leukocyte rolling is mediated by P-selectin and that firm leukocyte adhesion is supported by lymphocyte function antigen-1 in radiation-induced enteritis. Moreover, P-selectin-dependent leukocyte rolling is a precondition for subsequent leukocyte adhesion in radiation-induced intestinal injury. Thus, targeting P-selectin and/or lymphocyte function antigen-1 may protect against pathologic inflammation in the colon induced by radiotherapy.
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| 7. |
- Santén, Stefan, et al.
(författare)
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Mast-cell-dependent secretion of CXC chemokines regulates ischemia-reperfusion-induced leukocyte recruitment in the colon.
- 2008
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Ingår i: International Journal of Colorectal Disease. - : Springer Science and Business Media LLC. - 1432-1262 .- 0179-1958. ; 23, s. 527-534
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: Recruitment of leukocytes in the tissue microvasculature is considered to be a rate-limiting step in ischemia-reperfusion (I/R)-induced inflammation. The objective of this study was to examine the role of mast cells in CXC-chemokine- and I/R-provoked leukocyte recruitment in the colon. MATERIALS AND METHODS: Balb/c- and mast-cell-deficient mice were challenged with the CXC chemokines macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC) for 3 h. Leukocyte-endothelium interactions in the colonic microvascular bed were analyzed using an inverted intravital fluorescence microscopy technique. In separate experiments, mice were subjected to I/R by clamping of the superior mesenteric artery for 30 min followed by 120 min of reperfusion. RESULTS: MIP-2 and KC induced a clear-cut increase in the number of rolling and adherent leukocytes in the colon. I/R increased the expression of MIP-2 and KC as well as leukocyte rolling and adhesion in the large bowel. Interestingly, leukocyte rolling and adhesion was reduced by more than 91% in mast-cell-deficient mice in response to CXC chemokine challenge. Moreover, I/R-induced leukocyte rolling and adhesion was decreased by more than 57% in mast-cell-deficient animals. Administration of MIP-2 increased the colonic expression of E-selectin mRNA in wild type but not in mast-cell-deficient mice. CONCLUSION: Our data demonstrate that CXC chemokine-induced leukocyte rolling and adhesion is regulated by mast cells. Moreover, these findings also show that mast cells play a crucial role in supporting I/R-induced leukocyte rolling and adhesion in the colonic microvascular bed via secretion of CXC chemokines.
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| 8. |
- Santén, Stefan, et al.
(författare)
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P-selectin glycoprotein ligand-1 regulates chemokine-dependent leukocyte recruitment in colonic ischemia-reperfusion.
- 2007
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Ingår i: Inflammation Research. - : Springer Science and Business Media LLC. - 1420-908X .- 1023-3830. ; 56:11, s. 452-458
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Tidskriftsartikel (refereegranskat)abstract
- Objective and design: Leukocyte recruitment is a key feature in ischemia-reperfusion (I/R) -provoked tissue injury. This study evaluated the role of P-selectin-glycoprotein ligand-1 (PSGL-1) in CXC chemokine- and ischemia-reperfusion- induced leukocyte rolling and adhesion in the colon. Materials Balb/c mice were used in an inverted intravital fluorescence microscopy study of the microvascular bed in the colon. Treatment: Mice were challenged with macrophage inflammatory protein-2 (MIP-2) intraperitonally and leukocyte-endothelium interactions were analysed 3 h later. In separate experiments, mice were exposed to I/R by clamping of the superior mesenteric artery for 30 min and leukocyte rolling and adhesion were analysed after 120 min of reperfusion. Results: MIP-2 dose-dependently increased leukocyte rolling and adhesion in the colon. Pretreatment with an anti-PSGL-1 antibody reduced MIP-2-provoked leukocyte rolling and adhesion by more than 89%. I/R increased expression of MIP-2 as well as leukocyte rolling and adhesion. Immunoneutralization of PSGL-1 decreased reperfusion-induced leukocyte rolling by 85% and adhesion by 93% in colonic venules. Conclusions: Our data demonstrates that PSGL-1 is a dominant adhesion molecule supporting MIP-2- and I/R-provoked leukocyte rolling. Inhibition of PSGL-1 abolished leukocyte rolling and abrogated I/R-induced leukocyte adhesion in colonic venules. These findings suggest that targeting PSGL-1 may be an effective strategy to prevent I/R-induced inflammation in the colon.
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| 9. |
- Slotta, Jan, et al.
(författare)
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Inhibition of 3-Hydroxy-3-Methyl-Glutaryl-Coenzyme A Reductase Reduces Leukocyte Recruitment and Hepatocyte Apoptosis in Endotoxin-Induced Liver Injury.
- 2009
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Ingår i: Journal of Investigative Medicine. - 1708-8267. ; 57, s. 645-649
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:: Endotoxemia is well known to be associated with an excessive host response to bacteria or microbial compounds, resulting in systemic inflammation and organ injury. The aim of the present study was to examine the effects of simvastatin on endotoxemic liver injury. METHODS:: Male C57BL/6J mice were challenged intraperitoneally with 0.5 mg/kg Escherichia coli-lipopolysaccharide (LPS) and 0.9 g/kg d-galactosamine (Gal). Mice were pretreated with 0.2 mg/kg simvastatin. Lipopolysaccharide/d-Gal-injected mice without simvastatin served as endotoxemic controls, and sham mice served as negative controls. Additional mice were challenged with LPS/d-Gal and co-treated with simvastatin and 10 mg/kg mevalonate to determine the role of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. After 6 hours of endotoxemia serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities as well as caspase-3 and myeloperoxidase activity were determined. RESULTS:: Endotoxemia caused a substantial hepatocellular injury as indicated by significantly elevated serum ALT and AST levels and hepatocellular apoptosis. Leukocyte infiltration in the liver was significantly elevated in endotoxemic mice. Simvastatin significantly reduced endotoxin-induced hepatocellular damage and apoptosis. Moreover, hepatic accumulation of leukocytes was attenuated by simvastatin in endotoxemic animals. Co-administration of mevalonate abolished protective effects of simvastatin on endotoxin-provoked increases in ALT, AST, and hepatocellular apoptosis as well as leukocyte recruitment. CONCLUSIONS:: Simvastatin has the capacity to prevent endotoxemic liver injury by inhibiting leukocyte infiltration and hepatocellular apoptosis. These protective effects exerted by simvastatin are dependent on the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase pathway. Thus, simvastatin may represent a potential approach to prevent endotoxemia-associated liver dysfunction.
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| 10. |
- Thorlacius, Karin, et al.
(författare)
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Protective effect of fasudil, a Rho-kinase inhibitor, on chemokine expression, leukocyte recruitment, and hepatocellular apoptosis in septic liver injury.
- 2006
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 79:5, s. 923-931
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Tidskriftsartikel (refereegranskat)abstract
- Rho-kinase signaling regulates important features of inflammatory reactions. Herein, we investigated the effect and mechanisms of action of the Rho-kinase inhibitor fasudil in endotoxemic liver injury. C57/BL/6 mice were challenged with lipopolysaccharide (LPS) and D-galactosamine, with or without pretreatment with the Rho-kinase inhibitor fasudil. Six hours after endotoxin challenge, leukocyte-endothelium interactions in the hepatic microvasculature were studied by use of intravital fluorescence microscopy and tumor necrosis factor {alpha} (TNF-{alpha}); CXC chemokines as well as liver enzymes and apoptosis were determined. Administration of fasudil reduced LPS-induced leukocyte adhesion in postsinusoidal venules and sequestration in sinusoids. Moreover, we found that fasudil abolished extravascular infiltration of leukocytes as well as production of TNF-{alpha} and CXC chemokines in the liver of endotoxemic mice. Liver enzymes and hepatocellular apoptosis were markedly reduced, and sinusoidal perfusion was improved significantly in endotoxemic mice pretreated with fasudil. Our novel data document that fasudil is a potent inhibitor of endotoxin-induced expression of TNF-{alpha} and CXC chemokines as well as leukocyte infiltration and hepatocellular apoptosis in the liver. Based on the present findings, it is suggested that inhibition of the Rho-kinase signaling pathway may be a useful target in the treatment of septic liver injury.
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