| 1. |
- Hasan, Zirak, et al.
(författare)
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Rho-Kinase Signaling Regulates Pulmonary Infiltration of Neutrophils in Abdominal Sepsis via Attenuation of CXC Chemokine Formation and Mac-1 Expression on Neutrophils.
- 2012
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Ingår i: Shock. - 1540-0514. ; 37:3, s. 282-288
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: Excessive neutrophil infiltration is a major component in septic lung injury, although the signaling mechanisms behind pulmonary recruitment of neutrophils in polymicrobial sepsis remain elusive. Herein, we hypothesized that Rho-kinase activity may play a significant role in pulmonary neutrophil recruitment and tissue damage in abdominal sepsis. Male C57BL/6 mice were treated with the Rho-kinase inhibitor Y-27632 (0.5 or 5 mg/kg) before cecal ligation and puncture. Bronchoalveolar lavage fluid and lung tissue were harvested for analysis of neutrophil infiltration, as well as edema and CXC chemokine formation. Blood was collected for analysis of Mac-1 on neutrophils and CD40L on platelets as well as soluble CD40L and metalloproteinase-9 (MMP-9) in plasma. CLP triggered significant pulmonary damage characterized by neutrophil infiltration, increased levels of CXC chemokines, and edema formation in the lung. Furthermore, CLP up-regulated Mac-1 expression on neutrophils, decreased CD40L on platelets and increased soluble CD40L and MMP-9 in the circulation. Interestingly, inhibition of Rho-kinase dose-dependently decreased CLP-induced neutrophil expression of Mac-1, formation of CXC chemokines and edema as well as neutrophil infiltration and tissue damage in the lung. Moreover, Rho-kinase inhibition significantly reduced sepsis-provoked gene-expression of CXC chemokines in alveolar macrophages. In contrast, Rho-kinase inhibition had no effect on platelet shedding of CD40L or plasma levels of MMP-9 in septic mice. In conclusion, these data demonstrate that the Rho-kinase signaling pathway plays a key role in regulating pulmonary infiltration of neutrophils and tissue injury via regulation of CXC chemokine production in the lung and Mac-1 expression on neutrophils in abdominal sepsis.
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| 2. |
- Hwaiz, Rundk, et al.
(författare)
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Rac1 signaling regulates sepsis-induced pathologic inflammation in the lung via attenuation of Mac-1 expression and CXC chemokine formation.
- 2013
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 183:2, s. 798-807
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Tidskriftsartikel (refereegranskat)abstract
- Excessive neutrophil recruitment is a major feature in septic lung damage although the signaling mechanisms behind pulmonary infiltration of neutrophils in sepsis remain elusive. In the present study, we hypothesized that Rac1 might play an important role in pulmonary neutrophil accumulation and tissue injury in abdominal sepsis. Male C57BL/6 mice were treated with Rac1 inhibitor NSC23766 (5 mg/kg) before cecal ligation and puncture (CLP). Bronchoalveolar lavage fluid and lung tissue were collected for the quantification of neutrophil recruitment and edema and CXC chemokine formation. Blood was collected for the determination of Mac-1 on neutrophils and proinflammatory compounds in plasma. Gene expression of CXC chemokines and tumor necrosis factor alpha was determined by quantitative reverse transcription-polymerase chain reaction in alveolar macrophages. Rac1 activity was increased in lungs from septic animals, and NSC23766 significantly decreased pulmonary activity of Rac1 induced by CLP. Administration of NSC23766 markedly reduced CLP-triggered neutrophil infiltration, edema formation, and tissue damage in the lung. Inhibition of Rac1 decreased CLP-induced neutrophil expression of Mac-1 and pulmonary formation of CXC chemokines. Moreover, NSC23766 abolished the sepsis-evoked elevation of messenger RNA levels of CXC chemokines and tumor necrosis factor alpha in alveolar macrophages. Rac1 inhibition decreased the CLP-induced increase in plasma levels of high mobility group protein B1 and interleukin 6, indicating a role of Rac1 in systemic inflammation. In conclusion, our results demonstrate that Rac1 signaling plays a key role in regulating pulmonary infiltration of neutrophils and tissue injury via regulation of chemokine production in the lung and Mac-1 expression on neutrophils in abdominal sepsis. Thus, targeting Rac1 activity might be a useful strategy to protect the lung in abdominal sepsis.
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| 3. |
- Luo, Lingtao, et al.
(författare)
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Pro-inflammatory role of neutrophil extracellular traps in abdominal sepsis.
- 2014
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Ingår i: American Journal of Physiology: Lung Cellular and Molecular Physiology. - : American Physiological Society. - 1522-1504 .- 1040-0605. ; 307:7, s. 586-596
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Tidskriftsartikel (refereegranskat)abstract
- Excessive neutrophil activation is a major component in septic lung injury. Neutrophil-derived DNA may form extracellular traps in response to bacterial invasions. The aim of the present study was to investigate the potential role of neutrophil extracellular traps (NETs) in septic lung injury. Male C57BL/6 mice were treated with rhDNAse (5 mg/kg) after cecal ligation and puncture (CLP). Extracellular DNA was stained by Sytox green and NET formation was quantified by confocal microscopy and cell-free DNA in plasma, peritoneal cavity and lung. Blood, peritoneal fluid and lung tissue were harvested for analysis of neutrophil infiltration, NET levels, tissue injury as well as CXC chemokine and cytokine formation. We observed that CLP caused increased formation of NETs in the plasma, peritoneal cavity and lung. Administration of rhDNAse not only eliminated NET formation in the plasma, peritoneal cavity and bronchoalveolar space but also reduced lung edema and tissue damage 24 h after CLP induction. Moreover, treatment with rhDNAse decreased CLP-induced formation of CXC chemokines, IL-6 and HMGB1 in the plasma as well as CXC chemokines and IL-6 in the lung. In vitro, we found that neutrophil-derived NETs had the capacity to stimulate secretion of CXCL2, TNF-α and HMGB1 from alveolar macrophages. Taken together, our findings show that NETs regulate pulmonary infiltration of neutrophils and tissue injury via formation of pro-inflammatory compounds in abdominal sepsis. Thus, we conclude that NETs exert a pro-inflammatory role in septic lung injury.
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| 4. |
- Rahman, Milladur, et al.
(författare)
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Metalloproteinases regulate CD40L shedding from platelets and pulmonary recruitment of neutrophils in abdominal sepsis
- 2012
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Ingår i: Inflammation Research. - : Springer Science and Business Media LLC. - 1420-908X .- 1023-3830. ; 61:6, s. 571-579
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedOBJECTIVE: Platelets promote sepsis-induced activation of neutrophils via secretion of CD40L. However, the mechanism regulating the release of platelet-derived CD40L is not known. We hypothesized that matrix metalloproteinases (MMPs) might regulate shedding of platelet-expressed CD40L and neutrophil activation in sepsis.METHODS: Wild-type C57BL/6 mice were subjected to cecal ligation and puncture (CLP). Animals were pretreated with a broad-range MMP inhibitor, GM6001, prior to CLP induction. Edema formation, CXC chemokine and myeloperoxidase (MPO) levels and bronchoalveolar neutrophils in the lung as well as plasma levels of CD40L were quantified. Flow cytometry was used to determine expression of Mac-1 on neutrophils and CD40L on platelets. Intravital fluorescence microscopy was used to analyze leukocyte-endothelial cell interactions in the pulmonary microcirculation.RESULTS: The MMP inhibitor reduced sepsis-induced release of CD40L and maintained normal levels of CD40L on platelets. Inhibition of MMP decreased CLP-induced neutrophil expression of Mac-1, formation of CXC chemokines and edema as well as neutrophil infiltration in the lung. Intravital fluorescence microscopy revealed that the MMP inhibitor attenuated leukocyte adhesion in venules whereas capillary trapping of leukocytes was not affected by MMP inhibition.CONCLUSIONS: We describe a novel role of metalloproteinases in regulating platelet-dependent activation and infiltration of neutrophils in septic lung injury which might be related to controlling CD40L shedding from platelets. We conclude that targeting metalloproteinases may be a useful strategy for limiting acute lung injury in abdominal sepsis.
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| 5. |
- Wang, Yongzhi, et al.
(författare)
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Distinct patterns of leukocyte recruitment in the pulmonary microvasculature in response to local and systemic inflammation
- 2013
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Ingår i: American Journal of Physiology: Lung Cellular and Molecular Physiology. - : American Physiological Society. - 1522-1504 .- 1040-0605. ; 304:4, s. 298-305
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Tidskriftsartikel (refereegranskat)abstract
- Wang Y, Roller J, Slotta JE, Zhang S, Luo L, Rahman M, Syk I, Menger MD, Thorlacius H. Distinct patterns of leukocyte recruitment in the pulmonary microvasculature in response to local and systemic inflammation. Am J Physiol Lung Cell Mol Physiol 304: L298-L305, 2013. First published December 28, 2012; doi:10.1152/ajplung.00246.2012.The mechanisms of leukocyte recruitment in the pulmonary microvasculature in response to local and systemic inflammation remain elusive. Male C57BL/6 mice received lipopolysaccharide (LPS) intrapulmonary (intratracheally, it) or systemically (intravenously, iv) for 1-18 h. Leukocyte responses in lung were analyzed by use of intravital fluorescence microscopy. Plasma and lung levels of CXC chemokines as well as Mac-1 and F-actin expression in leukocytes and bronchoalveolar leukocytes were quantified. Venular leukocyte rolling was markedly increased in response to local LPS but only marginally after systemic LPS. Leukocyte adhesion in venules was enhanced in both groups although adhesion was higher in mice receiving LPS intratracheally compared with LPS intravenously. Systemic LPS caused more leukocytes trapping in capillaries compared with local LPS. The ratio of adherent leukocytes in venules compared with capillaries was higher in response to local LPS, suggesting that leukocytes were more prone to accumulate in venules in local inflammation and in capillaries in systemic inflammation. Systemic LPS triggered higher F-actin formation and Mac-1 expression in leukocytes compared with local LPS. Local and systemic LPS caused similar increases in CXC chemokines in the lung whereas intravenous endotoxin provoked higher levels of CXC chemokines in the circulation. Interestingly, intratracheal LPS increased recruitment of leukocytes in the alveolar space whereas intravenous LPS was ineffective in promoting leukocyte accumulation in the bronchoalveolar space. In conclusion, our data demonstrate that pulmonary microvascular recruitment of leukocytes differs in local and systemic inflammation, which might be related to premature activation and stiffening of circulating leukocytes in endotoxemia.
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| 6. |
- Zhang, Su, et al.
(författare)
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Simvastatin protects against T cell immune dysfunction in abdominal sepsis.
- 2012
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Ingår i: Shock. - 1540-0514. ; 38:5, s. 524-531
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: Sepsis-triggered immune paralysis including T-cell dysfunction increases susceptibility to infections. Statins exert beneficial effects in patients with sepsis, although the mechanisms remain elusive. Herein, we hypothesized that simvastatin may attenuate T-cell dysfunction in abdominal sepsis. Male C57BL/6 mice were pretreated with simvastatin (10 mg/kg) before cecal ligation and puncture (CLP). Spleen CD4 T-cell apoptosis, proliferation, and regulatory T cells (CD4CD25Foxp3) were quantified by use of flow cytometry. Formation of interferon γ (IFN-γ) and interleukin 4 (IL-4) in the spleen and plasma levels of high-mobility box group 1 (HMBG1) and IL-6 were determined using enzyme-linked immunosorbent assay. Cecal ligation and puncture caused a clear-cut increase in apoptosis and decrease in proliferation in splenic CD4 T cells. It was found that simvastatin markedly reduced apoptosis and improved proliferation in CD4 T cells in septic mice. Moreover, CLP-induced formation of regulatory T cells in the spleen was abolished in simvastatin-treated animals. Cecal ligation and puncture greatly decreased the levels of IFN-γ and IL-4 in the spleen. Simvastatin completely reversed this sepsis-mediated inhibition of IFN-γ and IL-4 formation in the spleen. We observed that CLP increased plasma levels of HMBG1 by 25-fold and IL-6 by 99,595-fold. Notably, treatment with simvastatin abolished this CLP-evoked increase in HMBG1 and IL-6 levels in the plasma, suggesting that simvastatin is a potent inhibitor of systemic inflammation in sepsis. Lastly, it was found that simvastatin reduced CLP-induced bacteremia. In conclusion, these novel findings suggest that simvastatin is a powerful regulator of T-cell immune dysfunction in abdominal sepsis. Thus, these protective effects of simvastatin on T-cell functions help to explain the protective effect of statins in patients with sepsis.
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