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| 2. |
- Abdulla, Aree, et al.
(författare)
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Role of platelets in experimental acute pancreatitis.
- 2011
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Ingår i: British Journal of Surgery. - : Oxford University Press (OUP). - 1365-2168 .- 0007-1323. ; 98, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:: Platelets not only control thrombosis and haemostasis but may also regulate inflammatory processes. Acute pancreatitis (AP) is characterized by changes in both coagulation and proinflammatory activities. The role of platelets in AP is not yet known. METHODS:: AP was induced in C57BL/6 mice by repeated caerulein administration (50 µg/kg intraperitoneally). Mice received a platelet-depleting or control antibody before caerulein challenge. Neutrophil infiltration, myeloperoxidase (MPO) and macrophage inflammatory protein (MIP) 2 levels, acinar cell necrosis and haemorrhage in the pancreas, as well as serum amylase activity, were determined 24 h after caerulein injection. In an alternative model of pancreatitis, L-arginine (4 g/kg intraperitoneally) was given twice with an interval of 1 h and tissue samples were taken after 72 h [Correction added after online publication 29 September 2010: in the preceding sentence, 4 mg/kg was corrected to 4 g/kg]. RESULTS:: Caerulein administration increased acinar cell necrosis, neutrophil infiltration, focal haemorrhage and serum amylase levels. Platelet depletion reduced acinar cell necrosis, haemorrhage and serum amylase levels in AP. Depletion of platelets decreased caerulein-induced MPO levels and neutrophil recruitment in the pancreas. Platelet depletion abolished caerulein-induced MIP-2 generation in the pancreas and circulation. The effects of platelet depletion on necrosis, neutrophils and MPO levels were confirmed in L-arginine-induced pancreatitis. CONCLUSION:: Platelets play a crucial role in AP by regulating neutrophil infiltration, most likely mediated by MIP-2 production in the pancreas. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.
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| 3. |
- Hasan, Zirak, et al.
(författare)
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Geranylgeranyl transferase regulates CXC chemokine formation in alveolar macrophages and neutrophil recruitment in septic lung injury
- 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. 221-229
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Tidskriftsartikel (refereegranskat)abstract
- Hasan Z, Rahman M, Palani K, Syk I, Jeppsson B, Thorlacius H. Geranylgeranyl transferase regulates CXC chemokine formation in alveolar macrophages and neutrophil recruitment in septic lung injury. Am J Physiol Lung Cell Mol Physiol 304: L221-L229, 2013. First published December 14, 2012; doi:10.1152/ajplung.00199.2012.-Overwhelming accumulation of neutrophils is a significant component in septic lung damage, although the signaling mechanisms behind neutrophil infiltration in the lung remain elusive. In the present study, we hypothesized that geranylgeranylation might regulate the inflammatory response in abdominal sepsis. Male C57BL/6 mice received the geranylgeranyl transferase inhibitor, GGTI-2133, before cecal ligation and puncture (CLP). 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. Gene expression of CXC chemokines, tumor necrosis factor-alpha (TNF-alpha), and CCL2 chemokine was determined by quantitative RT-PCR in isolated alveolar macrophages. Administration of GGTI-2133 markedly decreased CLP-induced infiltration of neutrophils, edema, and tissue injury in the lung. CLP triggered clear-cut upregulation of Mac-1 on neutrophils. Inhibition of geranylgeranyl transferase reduced CLP-evoked upregulation of Mac-1 on neutrophils in vivo but had no effect on chemokine-induced expression of Mac-1 on isolated neutrophils in vitro. Notably, GGTI-2133 abolished CLP-induced formation of CXC chemokines, TNF-alpha, and CCL2 in alveolar macrophages in the lung. Geranylgeranyl transferase inhibition had no effect on sepsis-induced platelet shedding of CD40L. In addition, inhibition of geranylgeranyl transferase markedly decreased CXC chemokine-triggered neutrophil chemotaxis in vitro. Taken together, our findings suggest that geranylgeranyl transferase is an important regulator of CXC chemokine production and neutrophil recruitment in the lung. We conclude that inhibition of geranylgeranyl transferase might be a potent way to attenuate acute lung injury in abdominal sepsis.
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| 4. |
- Hasan, Zirak, et al.
(författare)
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Rho-kinase regulates induction of T-cell immune dysfunction in abdominal sepsis.
- 2013
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Ingår i: Infection and Immunity. - 1098-5522. ; 81:7, s. 2499-2506
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Tidskriftsartikel (refereegranskat)abstract
- T-cell dysfunction increases susceptibility to infections in patients with sepsis. In the present study, we hypothesized that Rho-kinase signaling might regulate induction of T-cell dysfunction in abdominal sepsis. Male C57BL/6 mice were treated with the specific Rho-kinase inhibitor Y-27632 (5 mg/kg) prior to cecal ligation and puncture (CLP). Spleen CD4 T-cell apoptosis, proliferation and regulatory T-cells (CD4(+)CD25(+)Foxp3(+)) were determined by flow cytometry. Formation of IFN-γ and IL-4 in the spleen and plasma levels of HMBG1 and IL-6 were quantified by use of ELISA. It was found that CLP evoked apoptosis and decreased proliferation in splenic CD4 T-cells. Inhibition of Rho-kinase activity decreased apoptosis and enhanced proliferation of CD4 T-cells in septic animals. In addition, CLP-evoked induction of regulatory T-cells in the spleen was abolished by Rho-kinase inhibition. CLP reduced the levels of IFN-γ and IL-4 in the spleen. Pretreatment with Y-27632 inhibited the sepsis-induced decrease in IFN-γ but not IL-4 formation in the spleen. CLP increased plasma levels of HMGB1 by 20-fold and IL-6 by 19-fold. Inhibition of Rho-kinase decreased this CLP-evoked increase of HMGB1, IL-6 and IL-17 levels in the plasma by more than 60%, suggesting that Rho-kinase regulates systemic inflammation in sepsis. Moreover, we observed that pretreatment with Y-27632 abolished CLP-induced bacteremia. Together, our novel findings indicate that Rho-kinase is a powerful regulator of T-cell immune dysfunction in abdominal sepsis. Thus, targeting Rho-kinase signaling might be a useful strategy to improve T-cell immunity in patients with abdominal sepsis.
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Muhammad, Asad, et al.
(författare)
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P-selectin glycoprotein-ligand-1 regulates pulmonary recruitment of neutrophils in a platelet-independent manner in abdominal sepsis
- 2009
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 156:2, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil-mediated lung injury is an insidious feature in sepsis although the mechanisms regulating pulmonary recruitment of neutrophils remain elusive. Here, we investigated the role of P-selectin glycoprotein-ligand-1 (PSGL-1) in sepsis-induced neutrophil recruitment and tissue injury in the lung. Bronchoalveolar infiltration of neutrophils, levels of myeloperoxidase, oedema formation and CXC chemokines were determined 24 h after caecal ligation and puncture (CLP) in mice. Animals were pretreated with a control antibody, monoclonal antibodies directed against PSGL-1 and P-selectin as well as a platelet-depleting antibody directed against GP1b alpha. CLP caused pulmonary damage characterized by oedema formation, neutrophil infiltration and increased levels of CXC chemokines in the lung. Immunoneutralization of PSGL-1 or P-selectin reduced CLP-induced neutrophil recruitment in the bronchoalveolar space by more than 56% and lung myeloperoxidase activity by 62%. Notably, the inhibitory effect of the anti-PSGL-1 antibody on sepsis-induced neutrophil infiltration was also observed in platelet-depleted mice. Moreover, inhibition of PSGL-1 and P-selectin abolished CLP-induced oedema formation and tissue damage in the lung. CLP-induced formation of CXC chemokines was not changed in mice pretreated with the anti-PSGL-1 and anti-P-selectin antibodies. These data demonstrate that PSGL-1 plays a key role in pulmonary infiltration of neutrophils as well as lung oedema associated with abdominal sepsis. Moreover, our findings suggest that PSGL-1-dependent neutrophil recruitment is independent of circulating platelets. Thus, these novel findings indicate that PSGL-1 may be a useful target to protect against sepsis-induced accumulation of neutrophils and tissue damage in the lung.
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| 8. |
- Muhammad, Asad, et al.
(författare)
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Platelets support pulmonary recruitment of neutrophils in abdominal sepsis
- 2009
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Ingår i: Critical Care Medicine. - 1530-0293. ; 37:4, s. 1389-1396
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Recent findings Indicate that platelets not only regulate thrombosis and hemostasis but may also be involved in proinflammatory activities. Herein, we hypothesized that platelets may play a role in sepsis by activating and priming circulating neutrophils for subsequent recruitment Into the lung. Design: Prospective experimental study. Setting. University Hospital Research Unit. Subject. Male C57BL/6 mice. Interventions. Lung edema, bronchoalveolar infiltration of neutrophils, levels of myeloperoxidase, expression and function of membrane-activated complex-1 (Mac-1) on neutrophils and the CXC chemokines, macrophage inflammatory protein-2, and cytokine-induced neutrophil chemoattractant were determined after cecal ligation and puncture (CLP). Mice received a platelet-depleting antibody as well as antibodies directed against P-selectin glycoprotein-ligand-1 and Mac-1 before CLP induction. Measurements and Main Results. CLP caused 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 and increased the number of neutrophils binding platelets in the circulation. Interestingly, depletion of platelets reduced CLP-induced edema and neutrophil recruitment in the bronchoalveolar space by >60%. Furthermore, depletion of platelets reduced Mac-1 expression on neutrophils. On the other hand, inhibition of P-selectin glycoprotein-ligand-1 abolished CLP-induced neutrophil-platelet aggregation but had no effect on neutrophil expression of Mac-1. Conclusions: These data demonstrate that platelets play a key role in regulating infiltration of neutrophils and edema formation in the lung via upregulation of Mac-1 in abdominal sepsis. (Crit Care Med 2009; 37:1389-1396)
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| 9. |
- Palani, Karzan, et al.
(författare)
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Rho-kinase regulates adhesive and mechanical mechanisms of pulmonary recruitment of neutrophils in abdominal sepsis.
- 2012
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 682:1-3, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that Rho-kinase signaling plays a role in mechanical and adhesive mechanisms of neutrophil accumulation in lung. Male C57BL/6 mice were treated with the Rho-kinase inhibitor Y-27632 prior to cecal ligation and puncture (CLP). Lung levels of myeloperoxidase (MPO) and histological tissue damage were determined 6h and 24h after CLP. Expression of Mac-1 and F-actin formation in neutrophils were quantified by using flow cytometry 6h after CLP. Mac-1 expression and F-actin formation were also determined in isolated neutrophils up to 3h after stimulation with CXCL2. Labeled and activated neutrophils co-incubated with Y-27632, an anti-Mac-1 antibody and cytochalasin B were adoptively transferred to CLP mice. Y-27632 reduced the CLP-induced pulmonary injury and MPO activity as well as Mac-1 on neutrophils. Neutrophil F-actin formation peaked at 6h and returned to baseline levels 24h after CLP induction. Rho-kinase inhibition decreased CLP-provoked F-actin formation in neutrophils. CXCL2 rapidly increased Mac-1 expression and F-actin formation in neutrophils. Co-incubation with Y-27632 abolished CXCL2-induced Mac-1 up-regulation and formation of F-actin in neutrophils. Notably, co-incubation with cytochalasin B inhibited formation of F-actin but did not reduce Mac-1 expression on activated neutrophils. Adoptive transfer experiments revealed that co-incubation of neutrophils with the anti-Mac-1 antibody or cytochalasin B significantly decreased pulmonary accumulation of neutrophils in septic mice. Our data show that targeting Rho-kinase effectively reduces neutrophil recruitment and tissue damage in abdominal sepsis. Moreover, these findings demonstrate that Rho-kinase-dependent neutrophil accumulation in septic lung injury is regulated by both adhesive and mechanical mechanisms.
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| 10. |
- 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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