| 1. |
- Changhui, Yu, et al.
(författare)
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Rac1 signaling regulates neutrophil-dependent tissue damage in experimental colitis.
- 2014
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 741:Jul 30, s. 90-96
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Tidskriftsartikel (refereegranskat)abstract
- Excessive neutrophil recruitment in the colon is a major feature in acute colitis although the signaling mechanisms behind colonic recruitment of neutrophils remain elusive. Herein, we hypothesized that Rac1 activity might play an important role in neutrophil infiltration in the inflamed colon. Female Balb/c mice were treated with the Rac1 inhibitor NSC23766 (0.5 and 5mg/kg) before and daily after administration of 5% dextran sodium sulfate (DSS). Colonic tissue was collected for quantification of neutrophil recruitment, interleukin-6 (IL-6) and CXC chemokine formation as well as histological damage score five days after challenge with DSS. Rac1 activity was determined by western blot and Mac-1 expression by flow cytometry in neutrophils. Administration of NSC23766 decreased DSS-induced neutrophil recruitment and tissue damage in the colon. Rac1 inhibition decreased colonic formation of IL-6 and CXC chemokines in experimental colitis. Chemokine challenge increased Rac1 activity in neutrophils and NSC23766 markedly reduced this neutrophil activity of Rac1. Inhibition of Rac1 abolished CXC chemokine-induced neutrophil chemotaxis and up-regulation of Mac-1 in vitro. Taken together, Rac1 signaling plays a significant role in controlling accumulation of neutrophils and tissue injury in experimental colitis. Thus, our novel results suggest that targeting Rac1 signaling might be a useful way to protect against neutrophil-mediated tissue injury in acute colitis.
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| 2. |
- 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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| 3. |
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| 4. |
- Hwaiz, Rundk, et al.
(författare)
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Rac1-dependent secretion of platelet-derived CCL5 regulates neutrophil recruitment via activation of alveolar macrophages in septic lung injury.
- 2015
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Ingår i: Journal of Leukocyte Biology. - 1938-3673. ; 97:5, s. 975-984
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Tidskriftsartikel (refereegranskat)abstract
- Accumulating evidence suggest that platelets play an important role in regulating neutrophil recruitment in septic lung injury. Herein, we hypothesized that platelet-derived CCL5 might facilitate sepsis-induced neutrophil accumulation in the lung. Abdominal sepsis was induced by CLP in C57BL/6 mice. CLP increased plasma levels of CCL5. Platelet depletion and treatment with the Rac1 inhibitor NSC23766 markedly reduced CCL5 in the plasma of septic mice. Moreover, Rac1 inhibition completely inhibited proteasePAR4-induced secretion of CCL5 in isolated platelets. Immunoneutralization of CCL5 decreased CLP-induced neutrophil infiltration, edema formation, and tissue injury in the lung. However, inhibition of CCL5 function had no effect on CLP-induced expression of Mac-1 on neutrophils. The blocking of CCL5 decreased plasma and lung levels of CXCL1 and CXCL2 in septic animals. CCL5 had no effect on neutrophil chemotaxis in vitro, suggesting an indirect effect of CCL5 on neutrophil recruitment. Intratracheal challenge with CCL5 increased accumulation of neutrophils and formation of CXCL2 in the lung. Administration of the CXCR2 antagonist SB225002 abolished CCL5-induced pulmonary recruitment of neutrophils. Isolated alveolar macrophages expressed significant levels of the CCL5 receptors CCR1 and CCR5. In addition, CCL5 triggered significant secretion of CXCL2 from isolated alveolar macrophages. Notably, intratracheal administration of clodronate not only depleted mice of alveolar macrophages but also abolished CCL5-induced formation of CXCL2 in the lung. Taken together, our findings suggest that Rac1 regulates platelet secretion of CCL5 and that CCL5 is a potent inducer of neutrophil recruitment in septic lung injury via formation of CXCL2 in alveolar macrophages.
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| 5. |
- Hwaiz, Rundk, et al.
(författare)
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Rac1 regulates platelet shedding of CD40L in abdominal sepsis.
- 2014
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Ingår i: Laboratory Investigation. - : Elsevier BV. - 1530-0307 .- 0023-6837. ; 94:9, s. 1054-1063
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Tidskriftsartikel (refereegranskat)abstract
- Matrix metalloproteinase-9 (MMP-9) regulates platelet shedding of CD40L in abdominal sepsis. However, the signaling mechanisms controlling sepsis-induced shedding of CD40L from activated platelets remain elusive. Rac1 has been reported to regulate diverse functions in platelets; we hypothesized herein that Rac1 might regulate platelet shedding of CD40L in sepsis. The specific Rac1 inhibitor NSC23766 (N6-[2-[[4-(diethylamino)-1-methylbutyl] amino]-6-methyl-4-pyrimidinyl]-2 methyl-4, 6-quinolinediamine trihydrochloride) was administered to mice undergoing cecal ligation and puncture (CLP). Levels of CD40L and MMP-9 in plasma, platelets, and neutrophils were determined by use of ELISA, western blot, and confocal microscopy. Platelet depletion abolished the CLP-induced increase in plasma levels of CD40L. Rac1 activity was significantly increased in platelets from septic animals. Administration of NSC23766 abolished the CLP-induced enhancement of soluble CD40L levels in the plasma. Moreover, Rac1 inhibition completely inhibited proteinase-activated receptor-4-induced surface mobilization and secretion of CD40L in isolated platelets. CLP significantly increased plasma levels of MMP-9 and Rac1 activity in neutrophils. Treatment with NSC23766 markedly attenuated MMP-9 levels in the plasma from septic mice. In addition, Rac1 inhibition abolished chemokine-induced secretion of MMP-9 from isolated neutrophils. Finally, platelet shedding of CD40L was significantly reduced in response to stimulation with supernatants from activated MMP-9-deficient neutrophils compared with supernatants from wild-type neutrophils, indicating a direct role of neutrophil-derived MMP-9 in regulating platelet shedding of CD40L. Our novel data suggest that sepsis-induced platelet shedding of CD40L is dependent on Rac1 signaling. Rac1 controls surface mobilization of CD40L on activated platelets and MMP-9 secretion from neutrophils. Thus, our findings indicate that targeting Rac1 signaling might be a useful way to control pathologic elevations of CD40L in the systemic circulation in abdominal sepsis.Laboratory Investigation advance online publication, 21 July 2014; doi:10.1038/labinvest.2014.92.
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| 6. |
- Hwaiz, Rundk
(författare)
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Rac1 signaling regulates platelet-dependent inflammation abdominal sepsis
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sepsis is a systemic inflammatory response syndrome to a localized or systemic infection that leads to the over production of proinflammatory cytokines and the ultimate failure of multiple organ systems. However, little is known about the potential role of Rac1 in controlling sepsis-induced intracellular signaling pathways. We hypothesized that Rac1 might be involved in sepsis mediated signaling pathways leading to the activation of inflammatory cells. Paper (I), Rac1 signaling plays an important role in polymicrobial sepsis induced by cecal ligation and puncture (CLP). This study shows that Rac1 signaling regulates sepsis-induced inflammation in the lung by reducing chemokine production and Mac-1 expression on neutrophils. Rac1 inhibitor NSC23766 attenuates lung edema, tissue destruction and systemic pro-inflammatory cytokines in septic animals, suggesting that targeting Rac1 may be useful approach to protect against pulmonary injury in abdominal sepsis. Paper (II), in this study we showed that inhibition of Rac1 signaling protect sepsis-induced lung injury through two different mechanisms. First, Rac1 controls surface mobilization of CD40L on activated platelets and second, Rac1 regulates MMP-9 secretion from neutrophils. Our data indicate that inhibition of Rac1 signaling might be a useful target in order to control pathological secretion and shedding of CD40L into the systemic circulation in abdominal sepsis. Paper (III) This study indicates that Rac1 activity is increased in platelets and regulates platelet secretion of CCL5 in abdominal sepsis. Our findings show that CCL5 regulates neutrophil recruitment in septic lung injury via activation of alveolar macrophages leading to local secretion of CXCL2. Thus, our novel data not only elucidates complex mechanisms regulating pulmonary neutrophil trafficking in sepsis but also suggest that targeting Rac1 signaling and platelet-derived CCL5 might be a useful way to control pathological inflammation and tissue damage in the lung in abdominal sepsis. Paper (IV) Rac1 signaling is enhanced in platelets and regulates platelet secretion of CXCL4 in abdominal sepsis. This study indicates that CXCL4 controls neutrophil accumulation via secretion of CXCL2 from alveolar macrophages in septic lung injury. These findings not only delineate complex mechanisms of neutrophil trafficking in sepsis but also suggest that targeting platelet-derived CXCL4 might be an effective way to ameliorate inflammation and tissue damage in septic lung damage.
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| 7. |
- 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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| 8. |
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| 9. |
- Merza, Mohammed, et al.
(författare)
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Human thrombin-derived host defense peptides inhibit neutrophil recruitment and tissue injury in severe acute pancreatitis.
- 2014
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Ingår i: American Journal of Physiology: Gastrointestinal and Liver Physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 307:9, s. 914-921
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Tidskriftsartikel (refereegranskat)abstract
- Severe acute pancreatitis (AP) is characterized by leukocyte infiltration and tissue injury. Herein, we wanted to examine the potential effects of thrombin-derived host defense peptides (TDPs) in severe AP. Pancreatitis was provoked by infusion of taurocholate into the pancreatic duct or by intraperitoneal administration of L-arginine in C57BL/6 mice. Animals were treated with the TDPs GKY20 and GKY25 or a control peptide WFF25 30 min before induction of AP. TDPs reduced blood amylase levels, neutrophil infiltration, hemorrhage, necrosis and edema formation in the inflamed pancreas. Treatment with TDPs markedly attenuated the taurocholate-induced increase in plasma levels of CXCL2 and interleukin-6. Moreover, administration of TDPs decreased histone 3, histone 4 and MPO levels in the pancreas in response to taurocholate challenge. Interestingly, administration of TDPs abolished neutrophil expression of Mac-1 in mice with pancreatitis. In addition, TDPs inhibited CXCL2-induced chemotaxis of isolated neutrophils in vitro. Fluorescent-labeled TDP was found to directly bind to isolated neutrophils. Finally, a beneficial effect of TDPs was confirmed in L-arginine-induced pancreatitis. Our novel results demonstrate that TDPs exert protective effects against pathological inflammation and tissue damage in AP. These novel findings suggest that TDPs might be useful in the management of patients with severe AP.
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| 10. |
- Merza, Mohammed, et al.
(författare)
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Neutrophil Extracellular Traps Induce Trypsin Activation, Inflammation, and Tissue Damage in Mice with Severe Acute Pancreatitis.
- 2015
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Ingår i: Gastroenterology. - : Elsevier BV. - 1528-0012 .- 0016-5085. ; 149:7, s. 1920-1920
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils are involved in development of acute pancreatitis (AP), but it is not clear how neutrophil-induced tissue damage is regulated. In addition to secreting antimicrobial compounds, activated neutrophils eliminate invading microorganisms by expelling nuclear DNA and histones to form extracellular web-like structures called neutrophil extracellular traps (NETs). However, NETs have been reported contribute to organ dysfunction in patients with infectious diseases. We investigated whether NETs contribute to development of AP in mice.
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