Pentoxifylline reduces leukocyte retention in the coronary microcirculation early in reperfusion following ischemia

Pentoxifylline and nephroprotection: effects on renal dysfunction and cardiovascular risks

Generalized data on nephroprotective efficacy of pentoxifylline in chronic kidney disease (CKD) are presented. The potential of this drug in treating people suffering from CKD and cardiovascular diseases (CVD) with a high risk of developing the terminal stage of renal dysfunction is considered. Antiproteinuric, antifibrotic and anti-inflammatory effects of pentoxifylline significantly reduce the risk of progression of CKD and joining of CVD in the future. Efficacy in preventing the onset of the uremic stage of CKD, safety andapplicability at all stages of renal dysfunction development make pentoxifylline a very appealing drug not only for nephrologists but also for physicians. Keywords: chronic kidney disease, progression, pentoxifylline, nephroprotection, cardiovascular diseases.

The Effects of Pentoxifylline on the Myocardial Inflammation and Ischemia-Reperfusion Injury During Cardiopulmonary Bypass

BACKGROUND

Pentoxifylline (Ptx) decreases necessity of cell energy and inflammatory reactions via inhibition of 5'-nucleotidase (5'-NT). The aim of this study is to investigate whether the addition of Ptx into the cardioplegic solutions avoids myocardial inflammatory reactions and ischemia/reperfusion (I/R) injury during extracorpereal circulation.

METHODS

Between December 1999 and February 2002, we operated 75 patients with the diagnoses of atrial septal defect (ASD), ventricular septal defect (VSD), valve disease, and coronary disease. The average age of patients was 42.4 and male-female ratio was 1: 1.5. The patients were divided into two groups, which were the study group (n = 40) and the control group (n = 35). We used cold blood cardioplegia mixed with St. Thomas' Hospital II cardioplegic solution for both of the groups. Ptx was added into the cardioplegic solution (500 mg/L) in the study group. Interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrotisis factor-alpha (TNF-alpha) levels in coronary sinus blood samples during cross-clamp time (X-clamp) and after releasing of it and tissue TNF-alpha in the right atrial appendix biopsy material that was taken after X-clamp were studied to compare the both groups.

RESULTS

After releasing X-clamp, results of blood TNF-alpha, IL-6, and IL-8 of both groups were statistically significant (p < 0.005). At the pathological examination, we also observed that the amount of tissue TNF-alpha in the control group (66 +/- 17.1) was much higher than the study group (16.6 +/- 5.9, p <0.005).

CONCLUSIONS

These results show that Ptx may be added into cardioplegic solution to avoid the myocardial inflammation and I/R injury during open heart surgery.

A taurine-supplemented vegan diet may blunt the contribution of neutrophil activation to acute coronary events

Neutrophils are activated in the coronary circulation during acute coronary events (unstable angina and myocardial infarction), often prior to the onset of ischemic damage. Moreover, neutrophils infiltrate coronary plaque in these circumstances, and may contribute to the rupture or erosion of this plaque, triggering thrombosis. Activated neutrophils secrete proteolytic enzymes in latent forms which are activated by the hypochlorous acid (HOCl) generated by myeloperoxidase. These phenomena may help to explain why an elevated white cell count has been found to be an independent coronary risk factor. Low-fat vegan diets can decrease circulating leukocytes--neutrophils and monocytes--possibly owing to down-regulation of systemic IGF-I activity. Thus, a relative neutropenia may contribute to the coronary protection afforded by such diets. However, vegetarian diets are devoid of taurine - the physiological antagonist of HOCl--and tissue levels of this nutrient are relatively low in vegetarians. Taurine has anti-atherosclerotic activity in animal models, possibly reflecting a role for macrophage-derived myeloperoxidase in the atherogenic process. Taurine also has platelet-stabilizing and anti-hypertensive effects that presumably could reduce coronary risk. Thus, it is proposed that a taurine-supplemented low-fat vegan diet represents a rational strategy for diminishing the contribution of activated neutrophils to acute coronary events; moreover, such a regimen would work in a number of other complementary ways to promote cardiovascular health. Moderate alcohol consumption, the well-tolerated drug pentoxifylline, and 5-lipoxygenase inhibitors--zileuton, boswellic acids, fish oil--may also have potential in this regard.

Total artificial heart bridge to transplantation: a 9-year experience with 62 patients

BACKGROUND

The SynCardia CardioWest total artificial heart (CardioWest TAH) is a biventricular, orthotopic, pneumatic, pulsatile blood pump driven by an external console. For each ventricle, the length of the blood-flow path is shorter and the inflow and outflow valves are larger than in any other bridge-to-transplant device, resulting in greater blood flow at smaller pre-load. Such a device should be optimal for bridging transplant candidates who have biventricular failure and for whom all other therapies have failed.

METHODS

From January 1, 1993, to April 1, 2002, we prospectively studied 62 consecutive CardioWest TAH implant recipients to document safety and efficacy in bridge to transplantation. We used multisystem monitoring and multidrug therapy for anti-coagulation in 58 patients starting September 1, 1994.

RESULTS

Before implantation, patients were critically ill with biventricular heart failure. Mortality in this group from the time of implantation until transplantation was 23%. Causes of death during device support included multi-organ failure (6), sepsis (3), and valve entrapment (2). Forty-eight patients underwent transplantation (77%). Forty-two survived to hospital discharge (68% of the total, 88% of those undergoing transplantation). Adverse events included bleeding (20%), device malfunction (5%), fit complications (3%), mediastinal infections (5%), visceral embolus (1.6%), and stroke during support (1.6%). The linearized stroke rate was 0.068 events per patient-year.

CONCLUSIONS

Sixty-eight percent of critically ill transplant candidates for whom medical therapy failed were bridged to transplantation with the CardioWest TAH and survived long-term. Most deaths that occurred during device support were related to pre-implant problems. Infection and stroke were rare events. Therefore, we recommend the CardioWest TAH as the biventricular bridge-to-transplant device of choice.

Effects of pentoxifylline on the different steps during adhesion and transendothelial migration of flowing neutrophils

We used a flow system to observe the stepwise adhesion and migration of neutrophils on cultured human umbilical vein endothelial cells (HUVEC) stimulated with tumour necrosis factor-alpha (TNF) for 4 h, and to evaluate the effects of pentoxifylline (PTX) at each step. When HUVEC had been stimulated with 100 U ml(-1) TNF, treatment of neutrophils with PTX did not reduce the number captured from flow but did cause nearly all adherent cells ( > 90%) to roll, whereas most untreated cells became immobilized and approximately 30% transmigrated within minutes. On washout of the PTX, many rolling cells halted and started to migrate. Treatment of the HUVEC with PTX at the same time as 100 U ml(-1) TNF did not affect the number of neutrophils adhering, but there was a significant increase in the percentage of cells rolling even though PTX was no longer present. Thus PTX reduced presentation of activating agents by HUVEC, as well as inhibiting the response by neutrophils to surface-presented activating agent(s). If HUVEC were stimulated with 10 U ml(-1) TNF with PTX, the adhesion of flowing neutrophils was greatly inhibited compared to TNF alone. Surface ELISA indicated that PTX reduced TNF-induced upregulation of E-selectin. This reduction was only sufficient to reduce capture of neutrophils at the low dose of TNF. Thus, by using a flow-based model, we have been able to separate the effects of a multipotent agent such as pentoxifylline, which acts on leucocytes and endothelial cells, at each stage of migration.

Pentoxifylline reduces coronary leukocyte accumulation early in reperfusion after cold ischemia

BACKGROUND

Ischemia/reperfusion injury can complicate recovery in cardiac operations. Ischemia induces endothelial dysfunction, which may contribute to leukocyte accumulation during reperfusion. Leukocyte-mediated injury may then occur. Using intravital microscopy we previously reported increased leukocyte retention in coronary capillaries and venules during early reperfusion during warm ischemia/reperfusion. In this study we investigated whether cold cardioplegic protection would limit leukocyte sequestration in coronary microvessels early in reperfusion. Pentoxifylline (PTX) has antiinflammatory effects and may limit endothelial dysfunction during ischemia/reperfusion. The effect of cardioplegia modification with PTX was also examined.

METHODS

Isolated rat hearts were subjected to 90 minutes of 4 degrees C ischemia after arrest with cardioplegia. Hearts were reperfused with diluted whole blood containing fluorescent-labeled leukocytes. Leukocyte retention in coronary microvessels was observed with intravital microscopy. Three groups were studied, nonischemic control, cold ischemia, and PTX-modified cold ischemia.

RESULTS

In coronary capillaries, leukocyte trapping was nearly doubled in unmodified cold ischemia versus control. PTX modification significantly reduced leukocyte accumulation. In coronary venules, greater leukocyte adhesion was observed in unmodified cold ischemia compared to nonischemic controls. PTX modification significantly reduced leukocyte adhesion.

CONCLUSIONS

Cold cardioplegia did not prevent leukocyte retention in the coronary microcirculation early in reperfusion. PTX modification of cardioplegia significantly reduced leukocyte sequestration in coronary capillaries and venules. Preserving endothelial function during ischemia may limit leukocyte accumulation and ischemia/reperfusion injury after cardiac operation.

Leukocyte accumulation and hemodynamic changes in the cerebral microcirculation during early reperfusion after stroke

BACKGROUND AND PURPOSE

Leukocytes contribute to cerebral ischemia-reperfusion injury. However, few experimental models examine both in vivo behavior of leukocytes and microvascular rheology after stroke. The purpose of the present study was to characterize patterns of leukocyte accumulation in the cerebral microcirculation and to examine the relationship between leukocyte accumulation and microcirculatory hemodynamics after middle cerebral artery occlusion and reperfusion (MCAO-R).

METHODS

Male rats (250 to 350 g) were anesthetized and ventilated. Tail catheters were inserted for measurement of arterial blood gases and administration of drugs. Body temperature was maintained at 37 degrees C. Animals were subjected to 2 hours of MCAO by the filament method. A cranial-window preparation was performed, and the brain was superfused with warm, aerated artificial cerebrospinal fluid. Reperfusion was initiated by withdrawing the filament, and the pial microcirculation was observed by use of intravital fluorescence microscopy. Leukocyte accumulation in venules, arterioles, and capillaries; leukocyte rolling in venules; and leukocyte venular shear rate were assessed during 1 hour of reperfusion.

RESULTS

We found significant leukocyte adhesion in cerebral venules during 1 hour of reperfusion after 2 hours of MCAO. Leukocyte trapping in capillaries and adhesion to arterioles after MCAO-R tended to increase compared with controls, but the increase was not significant. We also found that shear rate was significantly reduced in venules during early reperfusion after MCAO.

CONCLUSIONS

A model using the filament method of stroke and fluorescence microscopy was used to examine white-cell behavior and hemodynamics in the cerebral microcirculation after MCAO-R. We observed a significant increase in leukocyte rolling and adhesion in venules and a significant decrease in blood shear rate in the microcirculation of the brain during early reperfusion. Leukocytes may activate and damage the blood vessels and surrounding brain cells, which contributes to an exaggerated inflammatory component to reperfusion. The model described can be used to examine precisely blood cell-endothelium interactions and hemodynamic changes in the microcirculation during postischemic reperfusion. Information from these and similar experiments may contribute to our understanding of the early inflammatory response in the brain during reperfusion after stroke.

Diabetes enhances leukocyte accumulation in the coronary microcirculation early in reperfusion following ischemia

BACKGROUND

Diabetic hearts are particularly vulnerable to ischemia-reperfusion injury. For leukocytes to participate in ischemia-reperfusion injury, they must first sequester in the microcirculation. The aim of this study was to determine, by direct observation, if early leukocyte deposition was increased in the diabetic coronary microcirculation early in reperfusion following myocardial ischemia.

METHODS

Non-diabetic and streptozotocin (STZ)-induced diabetic rat hearts, subjected to 30 min of 37 degrees C, no-flow ischemia, were initially reperfused with blood containing labeled leukocytes. The deposition of fluorescent leukocytes in coronary capillaries and venules was directly visualized and recorded using intravital fluorescence microscopy. In addition, flow cytometry was used to measure CD11b adhesion molecule expression on polymorphonuclear (PMN) leukocytes from non-diabetic and STZ-diabetic rats.

RESULTS

In the non-diabetic, control hearts, early in reperfusion, leukocytes trapped in coronary capillaries and adhered to the walls of post-capillary venules. In the diabetic hearts, leukocyte trapping in capillaries and adhesion to venules were both significantly increased (P<0.05). PMN CD11b expression was also significantly increased in the diabetic blood compared to the non-diabetic blood (P<0.05).

CONCLUSIONS

Early in reperfusion following myocardial ischemia, leukocytes rapidly accumulate in greater numbers in the coronary microcirculation of the diabetic heart by both trapping in coronary capillaries and by adhering to venules. The enhanced retention of leukocytes in the diabetic coronary microcirculation increases the likelihood of inflammation-mediated reperfusion injury and may explain, in part, the poor recovery of diabetic hearts from an ischemic event.

Fucoidin reduces coronary microvascular leukocyte accumulation early in reperfusion

BACKGROUND

Leukocytes rapidly accumulate in the heart early in reperfusion after ischemia, contributing to reperfusion injury. The purpose of this study was to determine whether treatment with the selectin blocker fucoidin (FCN) would attenuate early leukocyte retention in coronary venules and capillaries during low flow reperfusion.

METHODS

Isolated rat hearts subjected to 30 minutes of 37 degrees C, no-flow ischemia were initially reperfused with blood containing labeled leukocytes, followed by reperfusion with a Krebs red cell solution. The deposition of leukocytes in coronary capillaries and venules was observed using intravital microscopy. Three groups were studied: nonischemic control hearts, untreated postischemic hearts reperfused at low flow, and postischemic hearts reperfused at low flow, where both the hearts and the blood reperfusate were pretreated with FCN (0.36 mg/mL blood).

RESULTS

In the ischemia-reperfusion group, we observed a rapid and significant increase in leukocyte accumulation in both capillaries and venules. Treatment with FCN significantly reduced the leukocyte accumulation in both capillaries and venules (p<0.05). In addition, FCN significantly reduced the persistence of leukostasis in both capillaries and venules, indicating that FCN affected a transient adhesion process.

CONCLUSIONS

These results suggest that the selectin family of leukocyte-endothelial cell adhesion proteins mediates the initial retention of leukocytes in both coronary capillaries and venules during reperfusion. Selectin blockade may be effective in reducing the contribution of leukocytes to early reperfusion injury.