| 1. |
- Ding, Zhiyi, et al.
(författare)
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Actin-related protein 2/3 complex regulates neutrophil extracellular trap expulsion and lung damage in abdominal sepsis
- 2022
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Ingår i: American Journal of Physiology - Lung Cellular and Molecular Physiology. - 1040-0605. ; 322:5, s. 662-672
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil extracellular trap (NET) formation is a key feature in sepsis. The aim of the present study was to examine the role of the actin cytoskeleton in regulating the expulsion of NETs. Actin-related protein 2/3 (Arp 2/3) complex is an important regulator of F-actin polymerization. Coincubation with CK666, a specific Arp 2/3 inhibitor, decreased 12-phorbol 13-myristate acetate-induced NET formation in vitro. CK666 not only abolished F-actin polymerization but also caused intracellular retention of NETs. Inhibition of Arp 2/3 reduced NET formation on circulating neutrophils and in the bronchoalveolar space in mice undergoing cecal ligation and puncture (CLP). Notably, treatment with CK666 attenuated CLP-induced neutrophil recruitment, edema formation, and tissue damage in the lungs. Moreover, Arp 2/3 inhibition decreased levels of C-X-C motif chemokine ligand 1 (CXCL-1) and interleukin-6 in the lung and plasma of septic animals. Taken together, this study shows that expulsion of NETs is regulated by the actin cytoskeleton and that inhibition of Arp 2/3-dependent F-actin polymerization not only decreases NET formation but also protects against pathological inflammation and tissue damage in septic lung injury. Thus, we suggest that targeting NET release is a novel and useful way to ameliorate lung damage in abdominal sepsis.
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| 2. |
- Du, Feifei, et al.
(författare)
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E3 Ubiquitin Ligase Midline 1 Regulates Endothelial Cell ICAM-1 Expression and Neutrophil Adhesion in Abdominal Sepsis
- 2023
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Septic lung damage is associated with endothelial cell and neutrophil activation. This study examines the role of the E3 ubiquitin ligase midline 1 (Mid1) in abdominal sepsis. Mid1 expression was increased in endothelial cells derived from post-capillary venules in septic mice and TNF-α challenge increased Mid1 levels in endothelial cells in vitro. The siRNA-mediated knockdown of Mid1 decreased TNF-α-induced upregulation of ICAM-1 and neutrophil adhesion to endothelial cells. Moreover, Mid1 silencing reduced leukocyte adhesion in post-capillary venules in septic lungs in vivo. The silencing of Mid1 not only decreased Mid1 expression but also attenuated expression of ICAM-1 in lungs from septic mice. Lastly, TNF-α stimulation decreased PP2Ac levels in endothelial cells in vitro, which was reversed in endothelial cells pretreated with siRNA directed against Mid1. Thus, our novel data show that Mid1 is an important regulator of ICAM-1 expression and neutrophil adhesion in vitro and septic lung injury in vivo. A possible target of Mid1 is PP2Ac in endothelial cells. Targeting the Mid1-PP2Ac axis may be a useful way to reduce pathological lung inflammation 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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Ticagrelor reduces neutrophil recruitment and lung damage in abdominal sepsis.
- 2014
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Ingår i: Platelets. - : Informa UK Limited. - 1369-1635 .- 0953-7104. ; 25:4, s. 257-263
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Platelets play an important role in abdominal sepsis and P2Y12 receptor antagonists have been reported to exert anti-inflammatory effects. Herein, we assessed the impact of platelet inhibition with the P2Y12 receptor antagonist ticagrelor on pulmonary neutrophil recruitment and tissue damage in a model of abdominal sepsis. Wild-type C57BL/6 mice were subjected to cecal ligation and puncture (CLP). Animals were treated with ticagrelor (100 mg/kg) or vehicle prior to CLP induction. Edema formation and bronchoalveolar neutrophils as well as lung damage were quantified. Flow cytometry was used to determine expression of platelet-neutrophil aggregates, neutrophil activation and CD40L expression on platelets. CLP-induced pulmonary infiltration of neutrophils at 24 hours was reduced by 50% in ticagrelor-treated animals. Moreover, ticagrelor abolished CLP-provoked lung edema and decreased lung damage score by 41%. Notably, ticagrelor completely inhibited formation of platelet-neutrophil aggregates and markedly reduced thrombocytopenia in CLP animals. In addition, ticagrelor reduced platelet shedding of CD40L in septic mice. Our data indicate that ticagrelor can reduce CLP-induced pulmonary neutrophil recruitment and lung damage suggesting a potential role for platelet antagonists, such as ticagrelor, in the management of patients with 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, Songen, et al.
(författare)
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p38 Mitogen-activated protein kinase signaling regulates streptococcal M1 protein-induced neutrophil activation and lung injury.
- 2012
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 91, s. 137-145
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Tidskriftsartikel (refereegranskat)abstract
- M1 serotype of Streptococcus pyogenes can cause STSS and acute lung damage. Herein, the purpose was to define the role of p38 MAPK signaling in M1 protein-induced pulmonary injury. Male C57BL/6 mice were treated with specific p38 MAPK inhibitors (SB 239063 and SKF 86002) prior to M1 protein challenge. Edema, neutrophil infiltration, and CXC chemokines were determined in the lung, 4 h after M1 protein administration. Flow cytometry was used to determine Mac-1 expression. Phosphorylation and activity of p38 MAPK were determined by immunoprecipitation and Western blot. IVM was used to analyze leukocyte-endothelium interactions in the pulmonary microcirculation. M1 protein challenge increased phosphorylation and activity of p38 MAPK in the lung, which was inhibited by SB 239063 and SKF 86002. Inhibition of p38 MAPK activity decreased M1 protein-induced infiltration of neutrophils, edema, and CXC chemokine formation in the lung, as well as Mac-1 up-regulation on neutrophils. IVM showed that p38 MAPK inhibition reduced leukocyte rolling and adhesion in the pulmonary microvasculature of M1 protein-treated mice. Our results indicate that p38 MAPK signaling regulates neutrophil infiltration in acute lung injury induced by streptococcal M1 protein. Moreover, p38 MAPK activity controls CXC chemokine formation in the lung, as well as neutrophil expression of Mac-1 and recruitment in the pulmonary microvasculature. In conclusion, these findings suggest that targeting the p38 MAPK signaling pathway may open new opportunities to protect against lung injury in streptococcal infections.
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| 7. |
- 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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