| 1. |
- 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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| 2. |
- 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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| 3. |
- Wang, Feng, et al.
(författare)
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Anti-CD44 Monoclonal Antibody Inhibits Heart Transplant Rejection Mediated by Alloantigen-primed CD4(+) Memory T Cells in Nude Mice
- 2010
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Ingår i: Immunological Investigations. - : Informa UK Limited. - 0882-0139 .- 1532-4311. ; 39:8, s. 807-819
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Tidskriftsartikel (refereegranskat)abstract
- Donor-reactive CD4(+) memory T cells threaten the survival of transplanted organs. In this study, we used anti-CD44 monoclonal antibody (mAb) to inhibit adoptively transferred B6-reactive CD4(+) memory T cells (BALB/c origin) and to induce tolerance of B6 hearts in nude mice. The median survival time (MST) of the grafts was 6 days in the isotype group, and more than 100 days in the group treated with 8 doses of anti-CD44 at four-day intervals. Histological analysis revealed that the mean rejection level was Grade 3 in the isotype group, and Grade 0 or 1 in the multi-dose anti-CD44 treatment group. Compared with the isotype group, the multiply treated anti-CD44 group had significantly decreased IL-2 and IFN-gamma expressions, while IL-10 and TGF-beta were increased in the serum and the graft. Foxp3 in the graft was also increased. These data demonstrate that alloreactive CD4(+) memory T cells mediate the destruction of allografts, and the adhesion molecule CD44 plays an important role in this course. Anti-CD44 mAb may promote the reduction of CD4(+) memory T cells and the production of regulatory T cells (Tregs). Furthermore, Tregs are maintained at a certain level while suppressing cellular immunity and inducing the grafts long-term survival in transplant recipients.
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| 4. |
- 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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| 5. |
- Wang, Yongzhi, et al.
(författare)
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DYNAMIC CHANGES IN THROMBIN GENERATION IN ABDOMINAL SEPSIS IN MICE.
- 2014
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Ingår i: Shock. - 1540-0514. ; 42:4, s. 343-349
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT-Systemic inflammatory response syndrome and severe infections are associated with major derangements in the coagulation system. The purpose of this study was to examine the dynamic alterations in thrombin generation in abdominal sepsis. Abdominal sepsis was induced by cecal ligation and puncture (CLP) in C57/Bl6 mice. CLP caused a systemic inflammatory response with neutrophil recruitment and tissue damage in the lung as well as thrombocytopenia and leukocytopenia. Thrombin generation, coagulation factors, lung histology and myeloperoxidase (MPO) activity was determined 1h, 3h, 6h and 24h after induction of CLP. It was found that thrombin generation was increased 1h after CLP and that thrombin generation started to decrease at 3h and was markedly reduced 6h and 24h after CLP induction. Platelet poor plasma from healthy mice could completely reverse the inhibitory effect of CLP on thrombin generation, suggesting that sepsis caused a decrease in the levels of plasma factors regulating thrombin generation in septic animals. Indeed, it was found that CLP markedly decreased plasma levels of prothrombin, factor V and factor X at 6h and 24h. Moreover, we observed that CLP increased plasma levels of activated protein C at 6h, which returned to baseline levels 24h after CLP induction. Finally, pretreatment with imipenem/cilastatin attenuated the CLP-evoked decrease in thrombin generation and consumption of prothrombin 24h after CLP induction. Our novel findings suggest that thrombin generation is initially increased and later decreased in abdominal sepsis. Sepsis-induced reduction in thrombin generation is correlated to changes in the plasma levels of coagulation factors and activated protein C. These findings help explain the dynamic changes in global hemostasis in abdominal sepsis.
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| 6. |
- Wang, Yongzhi, et al.
(författare)
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Sepsis-induced leukocyte adhesion in the pulmonary microvasculature in vivo is mediated by CD11a andCD11b.
- 2013
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 702:1-3, s. 135-141
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Tidskriftsartikel (refereegranskat)abstract
- Leukocyte accumulation is a rate-limiting step in inflammatory lung injury. The aim of this study was to define the role of CD11a/CD18 and CD11b/CD18 in sepsis-induced leukocyte rolling and adhesion in lung arterioles, capillaries and venules in male C57BL/6 mice using intravital fluorescence microscopy. Cecal ligation and puncture (CLP) markedly increased leukocyte rolling in arterioles and venules but not in capillaries in the lung. Immunoneutralization of CD11a, but not CD11b, decreased CLP-provoked leukocyte rolling in lung arterioles. Inhibition of CD11a or CD11b abolished CLP-induced arteriolar and venular leukocyte adhesion. Immunoneutralization of CD11a and CD11b reduced sepsis-induced leukocyte sequestration in pulmonary capillaries. Moreover, blocking CD11a or CD11b function improved microvascular blood flow in the lung of CLP animals. Considered together, our novel findings show that CD11a and CD11b mediate leukocyte adhesion in both arterioles and venules as well as trapping in capillaries in the lung. In addition, our data demonstrate that CD11a but not CD11b supports leukocyte rolling in pulmonary arterioles. Thus, these findings elucidate the molecular mechanisms behind leukocyte-endothelium interactions in the lung during systemic inflammation.
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| 7. |
- Xia, Junjie, et al.
(författare)
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Suppressing memory T cell activation induces islet allograft tolerance in alloantigen-primed mice
- 2010
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Ingår i: Transplant International. - : Frontiers Media SA. - 1432-2277 .- 0934-0874. ; 23:11, s. 1154-1163
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Tidskriftsartikel (refereegranskat)abstract
- P>Memory T cells are known to play a key role in prevention of allograft tolerance in alloantigen-primed mice. Here, we used an adoptively transferred memory T cell model and an alloantigen-primed model to evaluate the abilities of different combinations of monoclonal antibodies (mAb) to block key signaling pathways involved in activation of effector and memory T cells. In the adoptively transferred model, the use of anti-CD134L mAb effectively prevented activation of CD4+ memory T cells and significantly prolonged islet survival, similar to the action of anti-CD122 mAb to CD8+ memory T cells. In the alloantigen-primed model, use of anti-CD134L and anti-CD122 mAbs in addition to co-stimulatory blockade with anti-CD154 and anti-LFA-1 prolonged secondary allograft survival and significantly reduced the proportion of memory T cells; meanwhile, this combination therapy increased the proportion of regulatory T cells (Tregs) in the spleen, inhibited lymphocyte infiltration in the graft, and suppressed alloresponse of recipient splenic T cells. However, we also detected high levels of alloantibodies in the serum which caused high levels of damage to the allogeneic spleen cells. Our results suggest that combination of four mAbs can significantly suppress the function of memory T cells and prolong allograft survival in alloantigen primed animals.
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| 8. |
- Zhang, Su, et al.
(författare)
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NFAT regulates neutrophil recruitment, systemic inflammation and T-cell dysfunction in abdominal sepsis.
- 2014
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Ingår i: Infection and Immunity. - 1098-5522. ; 82:8, s. 3275-3288
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Tidskriftsartikel (refereegranskat)abstract
- The signaling mechanisms regulating neutrophil recruitment, systemic inflammation and T-cell dysfunction in polymicrobial sepsis are not clear. This study explored the potential involvement of the calcium/calcineurin-dependent transcription factor, nuclear factor of activated T-cells (NFAT) in abdominal sepsis. Cecal ligation and puncture (CLP) triggered NFAT-dependent transcriptional activity in the lung, spleen, liver and aorta in NFAT-luciferase reporter mice. Treatment with the NFAT inhibitor A-285222 prior to CLP completely prevented sepsis-induced NFAT activation in all these organs. Inhibition of NFAT activity reduced sepsis-induced formation of CXCL1, CXCL2 and CXCL5 chemokines and edema as well as neutrophil infiltration in the lung. Notably, NFAT inhibition efficiently reduced the CLP-evoked increases in HMBG1, IL-6 and CXCL5 levels in plasma. Moreover, administration of A-285222 restored sepsis-induced T-cell dysfunction, as evidenced by markedly decreased apoptosis and restored proliferative capacity of CD4 T-cells. Along these lines, treatment with A-285222 restored IFN-γ and IL-4 levels in the spleen, which were markedly reduced in septic mice. CLP-induced formation of regulatory T-cells (CD4(+)CD25(+)Foxp3(+)) in the spleen was also abolished in A-285222-treated animals. Altogether, these novel findings suggest that NFAT is a powerful regulator of pathological inflammation and T-cell immune dysfunction in abdominal sepsis. Thus, our data suggest that NFAT signaling might be a useful target to protect against respiratory failure and immunosuppression in patients with sepsis.
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| 9. |
- 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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| 10. |
- 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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