Phosphodiesterase type 4 inhibition of activated polymorphonuclear leukocytes in a simulated extracorporeal circulation model

Myeloid Progenitor Inhibitory Factor-1 (CCL23) Inhibits Lung Leukocyte Recruitment in a Primate Cardiopulmonary Bypass-Induced Pulmonary Ischaemia Model

BACKGROUND

Bone marrow (BM)-derived polymorphonuclear leukocytes (PMNs) and monocytes (MO) induced by cardiopulmonary bypass (CPB) are highly proteolytic and cause postoperative lung injury. Although CCL23/Myeloid progenitor inhibitory factor-1 is a human CC chemokine with potent suppressor effects on myeloid progenitor cells, in vivo inhibitory effects on BM-derived leukocyte kinetics associated with CPB are unknown.

METHODS

Two-hour CPB was surgically performed in cynomolgus monkeys and BM-derived leukocytes kinetics were monitored postoperatively by flow cytometry with 5'-bromo-2'-deoxyuridine (BrdU) and cytokine ELISA. Monkeys were given CCL23 (n=5) or saline (control, n=5) intravenously daily for 3 days before BrdU labelling and peripheral blood/bronchoalveolar lavage fluid (BALF) timepoint sampling to reveal BrdU-labelled cells. Levels of cytokines, CD11b, and L-selectin were considered leukocytic activation markers.

RESULTS

The CCL23 treatment significantly prolonged BM transit of leukocytes (PMNs, 118.4±11.7-95.5±4.1 hours [control]; MO, 91.6±5.0-62.0±3.0 hours [control]) and reduced their alveolar appearance. The BM pool size of MO was decreased by CCL23 but PMNs were unaffected. CD11b, L-selectin expression of PMNs and MO during CPB, and post-surgical increases of interleukin (IL)-6, IL-8, TNF-α, MCP-1, and PMN elastase in the BALF were not suppressed.

CONCLUSIONS

CCL23 treatment slows turnover of PMN and MO progenitors in BM and suppresses their circulatory release and lung recruitment. CCL23 has inhibitory effects specifically on the CPB-induced BM response and could hold value for preventing CPB-induced lung injury.

Relationship between alcohol habits and hemorheology by a micro channel method in a general population

BACKGROUND

Hemorheology plays an important role in the development of cardiovascular disease. The Micro Channel array Flow Analyzer (MC-FAN) (Hitachi Haramachi Electronics Co., Ltd., Bentencho, Japan) is currently considered a useful new device to analyze hemorheology. However, the relationships between various lifestyle habits and hemorheology, especially using MC-FAN, have still not been thoroughly investigated.

HYPOTHESIS

The study was undertaken to determine whether there could be some correlations of lifestyle factors to hemorheology by MC-FAN.

METHODS

A total of 250 asymptomatic Japanese subjects (male:female = 100:150; mean age = 49.7 y) without any medication were enrolled in the present study. Hemorheology was assessed by the whole blood passage time (WBPT) and was corrected by the saline passage time using MC-FAN. Subjects' lifestyle factors, such as smoking habits, alcohol habits, and physical activity, were self-reported.

RESULTS

Partial correlation analysis for WBPT, after controlling for age, gender, hematocrit, white blood cell count, body mass index, blood pressure, blood biochemical measures, and all lifestyle habits, revealed a significant and inverse correlation between alcohol habits of 1-3 go (amount of alcohol intake) and WBPT (r = - 0.191, p = 0.003), in addition to a significant positive correlation between serum low-density lipoprotein (LDL) cholesterol and WBPT.

CONCLUSIONS

These data suggest that alcohol habits may beneficially affect hemorheology by MC-FAN, expanding the protective effect of light-to-moderate alcohol consumption against cardiovascular disease.

Leukocytes-depleting filters preferentially remove activated leukocytes and reduce the expression of surface adhesion molecules during the simulated extracorporeal circulation of human blood

The effect of leukocyte-depleting filters on the total and activated leukocyte counts and the expression of surface adhesion molecules CD11b, CD18, and CD62L during the in vitro extracorporeal circulation of human blood was studied. A 200 ml blood sample was taken from 10 patients undergoing CABG surgery. The blood was circulated for 60 minutes within an experimental extracorporeal circuit. A leukocyte-depleting filter was attached in five circuits (filtered group). In five other circuits, no filter was used (controls). Total leukocyte counts were determined manually. Activated leukocytes were identified using nitroblue tetrazolium staining. The expression of CD11b, CD18, and CD62L was measured with flow cytometry. At 60 minutes, total leukocyte counts were reduced by 49% from the baseline values in the filtered group and 10% in the control group (p < 0.0001). Activated leukocyte counts decreased by 86% in the filtered group and increased by 116% in the control group (p < 0.0001). In the filtered group, the expression of CD11b, CD18, and CD612L decreased by 60%, 21%, and 79%, respectively, and in the control group it increased by 24%, 6%, and 28% (p < 0.0001). Leukocyte-depleting filters preferentially remove activated leukocytes and reduce the expression of CD11b, CD18, and CD62L during the in vitro extracorporeal circulation of human blood.

Sivelestat reduces inflammatory mediators and preserves neutrophil deformability during simulated extracorporeal circulation

BACKGROUND

Neutrophil is a major focus in efforts to ameliorate the systemic inflammatory response associated with cardiopulmonary bypass. Neutrophil elastase is a powerful proteolytic enzyme, and plays a pivotal role in the development of the inflammatory response. This study assesses the inhibitory effects of sivelestat, a highly specific neutrophil elastase inhibitor, on elastase levels, cytokine production, and the functional changes of neutrophils in a simulated extracorporeal circulation model.

METHODS

Simulated recirculation was established by recirculating heparinized (3.75 U/mL) human blood for 120 minutes in an oxygenator and a roller pump circuit with and without 100 micromol/L of sivelestat (n = 7 for each group). Neutrophil elastase and interleukin-8 were measured with an enzyme immunoassay. Neutrophil deformability was evaluated by simulated microcapillaries. The neutrophil F-actin and the expression of CD11b and L-selectin were measured by flow cytometry.

RESULTS

Sivelestat reduced both neutrophil elastase levels (p = 0.0006) and interleukin-8 production (p < 0.0001) at 120 minutes of recirculation. Sivelestat also significantly preserved neutrophil deformability (p = 0.017) and reduced F-actin expression (p = 0.0037). The drug did not modulate the changes of CD11b or L-selectin.

CONCLUSIONS

This study suggests that specific elastase inhibition with sivelestat could be a feasible therapeutic strategy for patients undergoing cardiopulmonary bypass to attenuate neutrophil-derived inflammatory response and organ injuries.

Nafamostat preserves neutrophil deformability and reduces microaggregate formation during simulated extracorporeal circulation

BACKGROUND

Initial sequestration of activated neutrophils and platelet microaggregates in capillaries are responsible for the inflammatory response associated with cardiopulmonary bypass. The study assesses the inhibitory effects of nafamostat mesilate on neutrophil and platelet activation, and on the neutrophil deformability change and microaggregate formation during simulated extracorporeal circulation.

METHODS

Fresh heparinized human blood was recirculated for 120 minutes in a membrane oxygenator and a roller pump with and without nafamostat (1.0 mg bolus plus 8.0 mg/h infusion; n = 10 for each group). Neutrophil and platelet counts and platelet aggregation were measured. CD11b, L-selectin, and cytoplasmic F-actin of neutrophils were measured by flow cytometry. The microchannel transit time of whole blood was measured as a marker of neutrophil deformability and microaggregate formation. Neutrophil elastase and complement C4d were measured using enzyme immunoassay.

RESULTS

Nafamostat preserved platelet counts and inhibited platelet aggregation. Nafamostat significantly reduced neutrophil elastase release at 120 minutes of recirculation, and F-actin expression at 30 and 60 minutes. The drug did not modulate the changes of CD11b, L-selectin, or C4d. Whole blood filterability was significantly preserved by nafamostat at 30 and 120 minutes.

CONCLUSIONS

Nafamostat preserves blood filterability during recirculation, possibly by suppression of F-actin expression and platelet activation. Nafamostat may reduce neutrophil sequestration and microaggregate formation in the microcirculation during cardiopulmonary bypass.

Phosphodiesterase type 4 inhibitor rolipram inhibits activation of monocytes during extracorporeal circulation

OBJECTIVE

Cardiopulmonary bypass is associated with systemic inflammatory response syndrome and risk of multiorgan injury mediated by activated leukocytes. Phosphodiesterase type 4 is the predominant phosphodiesterase isozyme in leukocytes and plays a key role in the regulation of leukocyte activation. The aim of this study was to examine the effect of rolipram, a selective phosphodiesterase type 4 inhibitor, on functional changes of monocytes during simulated extracorporeal circulation.

METHODS AND RESULTS

Simulated extracorporeal circulation was established by recirculating heparinized human blood for 120 minutes on a membrane oxygenator with or without 10 micromol/L of rolipram. L-selectin and CD11b expression of monocytes were measured with flow cytometry. C4d fragment, Bb fragment, C5b-9, and interleukin-6 were measured with enzyme immunoassay. Rolipram reduced the increase in CD11b expression and the decrease in L-selectin expression of monocytes in response to simulated extracorporeal circulation. Rolipram inhibited the increase in C4d fragment and interleukin-6, but it did not affect the increase in Bb fragment or C5b-9.

CONCLUSION

Rolipram inhibited changes in adhesion molecule expression and interleukin-6 release by activated monocytes in simulated extracorporeal circulation. This study suggests that phosphodiesterase type 4 inhibition could be feasible therapeutic strategy to prevent exaggerated inflammatory response and organ injury in patients undergoing cardiopulmonary bypass.

PDE4 inhibitors as new anti-inflammatory drugs: effects on cell trafficking and cell adhesion molecules expression

Phosphodiesterase 4 (PDE4) is a major cyclic AMP-hydrolyzing enzyme in inflammatory and immunomodulatory cells. The wide range of inflammatory mechanisms under control by PDE4 points to this isoenzyme as an attractive target for new anti-inflammatory drugs. Selective inhibitors of PDE4 have demonstrated a broad spectrum of anti-inflammatory activities including the inhibition of cellular trafficking and microvascular leakage, cytokine and chemokine release from inflammatory cells, reactive oxygen species production, and cell adhesion molecule expression in a variety of in vitro and in vivo experimental models. The initially detected side effects, mainly nausea and emesis, appear at least partially overcome by the 'second generation' PDE4 inhibitors, some of which like roflumilast and cilomilast are in the later stages of clinical development for treatment of chronic obstructive pulmonary disease. These new drugs may also offer opportunities for treatment of other inflammatory diseases.

ONO-6818, a novel, potent neutrophil elastase inhibitor, reduces inflammatory mediators during simulated extracorporeal circulation

BACKGROUND

Among the serine proteases, neutrophil elastase is a powerful cytotoxic enzyme and plays a pivotal role in the inflammatory response associated with cardiopulmonary bypass. This study assesses the effects of the specific inhibition of neutrophil elastase by a novel, potent, low-molecular-weight neutrophil elastase inhibitor, ONO-6818. We hypothesized that ONO-6818 reduces inflammatory mediators and modulates adhesion molecules and the deformability of neutrophils during simulated extracorporeal circulation.

METHODS

Simulated extracorporeal circulation was established by recirculating fresh heparinized (3.75 U/mL) human blood for 120 minutes in a membrane oxygenator and a roller pump with and without 1.0 micromol/L of ONO-6818 (n = 9 for control group, n = 7 for ONO-6818 group). The neutrophil adhesion molecules, CD11b and L-selectin, and the cytoplasmic F-actin of neutrophils were measured by flow cytometry. Neutrophil deformability was evaluated using simulated silicon microcapillaries. Neutrophil elastase, interleukin 8, and C5b-9 were measured using enzyme immunoassay.

RESULTS

Neutrophil elastase levels were significantly lower in the ONO-6818 group. ONO-6818 significantly reduced interleukin 8 and C5b-9 production. ONO-6818 did not modulate changes of CD11b and L-selectin during recirculation. Cytoplasmic F-actin content and changes of neutrophil deformability did not significantly differ between the groups.

CONCLUSIONS

Inhibition of neutrophil elastase activity with ONO-6818 reduces further interleukin 8 production and the formation of the complement membrane attack complex, and this results in a reduction of neutrophil elastase levels during simulated extracorporeal circulation. This study suggests that specific neutrophil elastase inhibition with ONO-6818 is a feasible therapeutic option to attenuate the exaggerated inflammatory response associated with cardiopulmonary bypass.