Effects of polymyxin B on clinical signs, serum TNF-α, haptoglobin and plasma lactate concentrations in experimental endotoxaemia in sheep

Introduction

The experiment evaluated the effects of intravenous administration of polymyxin B on experimental endotoxaemia in sheep.

Material and Methods

Twenty clinically healthy fat-tailed sheep were randomly divided into: a group treated with 6,000 U/kg of polymyxin B, a group at 12,000 U/kg, and positive and negative controls. Endotoxaemia was induced by intravenous administration of lipopolysaccharide (LPS) from E. coli serotype O55:B5 at 0.5 μg/kg. polymyxin was infused intravenously along with 2.5 L of isotonic intravenous fluids at 20 mL/kg/h. The positive control group received LPS and 2.5 L of isotonic fluids, the negatives receiving just 2.5 L of isotonic fluids. Clinical signs were evaluated before and at 1.5, 3, 4.5, 6, 24, and 48 h after LPS administration. Blood was also sampled at the denoted hours and serum haptoglobin, tumour necrosis factor-α (TNF-α), and plasma lactate concentrations were assayed.

Results

The serum concentration of TNF-α in the positive control group increased significantly up to 48 h after LPS administration. The concentration of TNF-α was significantly different from those of the polymyxin B and positive control groups from 3 to 48 h; also, the concentrations of haptoglobin at different times in the polymyxin groups were lower than those of the positive control group and were significant at hours 3 to 48 (P < 0.05). Following the LPS administration, haptoglobin and TNF-α concentrations changed without significant difference between the two polymyxin B groups.

Conclusion

Polymyxin B (6,000 U/kg) restrained blood lactate concentrations. Furthermore, it significantly improved the clinical signs in endotoxaemic animals, including rectal temperature and heart and respiratory rates. Polymyxin B may be an antiendotoxic in fat-tailed sheep.

A new method for removing endotoxin from plasma using hemocompatible affinity chromatography technology, applicable for extracorporeal treatment of septic patients

The pathogenesis of sepsis begins with the proliferation of micro-organisms at a site of infection, followed by invasion of the bloodstream and other organs. Gram-negative bacteria account for a large part of sepsis cases. The structural component of Gram-negative bacteria, endotoxin or lipopolysaccharide (LPS), induces the synthesis and release of endogenous mediators of sepsis. A growing number of investigations of the molecular mechanisms occurring in sepsis, point to endotoxin as a central mediator leading to multi-organ failure and death. In numerous clinical trials, attempts to target molecules downstream of endotoxin have been made, but have not been associated with improved survival. We describe an affinity-based system for the selective removal of endotoxin from plasma. The small-scale device, a 1.5 ml cartridge, contains beads that bind endotoxin with high specificity and efficiency. In addition, evidence is presented that this device does not affect plasma hemostasis, nor does it activate the complement system. Taken together, these results represent a proof of principle for endotoxin removal from plasma, which may be of clinical value to treat sepsis by extracorporeal circulation of the blood through a scaled-up version of this endotoxin-removing device.

The effects of polymyxin B-immobilized fiber hemoperfusion on respiratory impairment in endotoxemic pigs

PURPOSE

This study investigated the effects of direct hemoperfusion with polymyxin B-immobilized fibers (PMX-DHP) on respiratory impairment in endotoxemic pigs.

MATERIALS AND METHODS

Thirteen anesthetized, mechanically ventilated pigs were divided into PMX-DHP (n=7) and control (n=6) groups. All pigs were hemodynamically monitored with the pulse index contour cardiac output (PiCCO) system (Pulsion Medical Systems, Munich, Germany) and infused intravenously with live Escherichia coli (LD50). In the PMX-DHP group, an arteriovenous extracorporeal circuit with a PMX column was applied for 30 to 150 minutes after endotoxin injection. We analyzed the laboratory data, arterial blood gas levels, and PiCCO variables (extravascular lung water [EVLW] and pulmonary vascular permeability index [PVPI]). Furthermore, we performed computed tomography of the chest in all pigs. The data were statistically analyzed with Student's t-test, the chi-square test, and the Mann-Whitney U-test.

RESULTS

With PMX-DHP endotoxemia significantly decreased and blood pressure increased 150 minutes after endotoxin injection. PiCCO revealed more cases of decreased EVLW in the PMX-DHP group. PVPI increased after endotoxin infusion in both groups. Computed tomography showed improvements in the PMX-DHP group. The survival rate was greater in the PMX-DHP group (100%) than in the control group (71%).

CONCLUSION

PMX-DHP is effective for treating respiratory impairment and contributes to the decreased mortality rate in the endotoxemic pigs.

Polymyxin B hemoperfusion: a mechanistic perspective

Direct hemoperfusion therapy with polymyxin B immobilized fiber cartridge (PMX-DHP) is an established strategy in the treatment of septic shock in Japan and parts of Western Europe. PMX-DHP is currently the subject of a pivotal North American randomized controlled trial (EUPHRATES) in patients with septic shock and confirmed endotoxemia, as measured by the endotoxin activity assay. The major mechanism of action of this therapy is the removal of circulating endotoxin. High affinity binding of circulating endotoxin by the PMX-DHP column may decrease circulating endotoxin levels by up to 90% after two standard treatments. Basic research has shown reductions in circulating cytokine levels and in renal tubular apoptosis. Clinical research has shown that PMX-DHP therapy results in hemodynamic improvements, improvements in oxygenation, renal function, and reductions in mortality. Further research is needed to further define additional patient populations with endotoxemia that may benefit from PMX-DHP therapy as well as to further elucidate dosing, timing, and additional information on mechanisms of action. This review will present the mechanistic rationale for this targeted strategy of endotoxin removal using PMX-DHP in endotoxemic septic patients, highlighting both the specific effects of the therapy and the evidence accumulated so far of clinical improvement following this therapy in terms of recovery of organ function.

A case of severe ARDS caused by novel swine-origin influenza (A/H1N1pdm) virus: a successful treatment with direct hemoperfusion with polymyxin B-immobilized fiber

In 2009, a 35-year-old female with Down syndrome was admitted to our hospital because of severe pneumonia caused by an infection with the novel swine-origin influenza (A/H1N1pdm) virus (S-OIV). A chest X-ray on admission revealed bilateral infiltration shadows. Although mechanical ventilation was administered because of the development of ARDS, the hypoxemia continued to progressed. We observed evidence of alveolar hemorrhage on evaluation of the patient using bronchofiberscopy. The bacterial examination was negative. Despite intensive care, including respiratory management with high-frequency oscillatory ventilation (HFOV), the patient's hypoxemia and hypotension progressed. We concluded that a cytokine storm due to the influenza infection with SIRS caused shock status, resulting in septic shock. We subsequently treated the patient with direct hemoperfusion with polymyxin B-immobilized fiber (PMX-DHP). The hypoxemia improved immediately. She was free from mechanical ventilation and discharged from the hospital by the 17th day of her hospitalization. PMX-DHP seems to improve hypoxemia in patients with severe ARDS who cannot maintain sufficient respiratory control under mechanical ventilation. This case is the first report about severe and life-threatening ARDS due to the novel influenza, in which PMX-DHP showed beneficial effects.

Effect of polymyxin B-immobilized fiber hemoperfusion on respiratory impairment, hepatocellular dysfunction, and leucopenia in a neonatal sepsis model

PURPOSE

Sepsis and septic shock remain a major source of morbidity and mortality in neonates despite advances in antimicrobials and aggressive supportive care. Our aim was to study the effects of polymyxin-B direct hemoperfusion (PMX-DHP) therapy on sepsis-induced respiratory impairment, liver dysfunction and leucopenia in a neonatal cecal ligation and perforation (CLP) model.

METHODS

Fourteen anesthetized and mechanically ventilated 3-day-old piglets underwent CLP and an arteriovenous extracorporeal circuit from 3 h until 6 h post-CLP, with a PMX column in the PMX-DHP treated group (7 piglets). Changes in oxygen saturation, PCO(2), base excess, white blood cell (WBC) count, platelet count, hematocrit (Hct%), serum glutamate pyruvate transaminase (SGPT), and serum glutamic oxaloacetic transaminase were measured before CLP and at 1, 3 and 6 h after.

RESULTS

At 6 h, the PMX-DHP group showed lower Hct%, and SGPT in comparison to the control group, but higher oxygen saturation and WBC count. No effects on the platelet count were found. The survival times of the PMX-DHP group were longer than in control.

CONCLUSION

PMX-DHP therapy limited the respiratory impairment, liver dysfunction and leucopenia in a neonatal septic model, which resulted in an improvement of survival time.

The effect of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) on pulmonary ischemia-reperfusion injury in a canine model

This study evaluates the effectiveness of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) on warm ischemia-reperfusion injury of the lung using a canine mode.

MATERIALS AND METHODS

Ten adult mongrel dogs weighing 13-16 kg were used. After a left thoracotomy, the left pulmonary artery and vein were clamped. The left main bronchus was also clamped and then divided, and complete ischemia of the left lung was maintained for 3 h. The left main bronchus was re-anastomosed before reperfusion of the left lung. The right pulmonary artery was ligated immediately after reperfusion of the left lung. The dogs were divided into two groups: the DHP-PMX group (n = 5, DHP-PMX was performed for 120 min, from 30 min before reperfusion to 90 min after reperfusion) and the control group (n = 5). The body temperature of the animals was maintained at 36 degrees C-37 degrees C during the experiment. The PaO2/FiO2 (P/F ratio), AaDO2, and lt-pulmonary vascular resistance (PVR) were measured at 30, 60, 120, 180, and 240 min after reperfusion in both groups, and the two groups were compared. The water content of the lung tissues and histopathology was also analyzed.

RESULTS

The P/F ratio decreased remarkably after reperfusion in the control group, and was significantly (p < .05) lower than that in the PMX-DHF group until 240 min after reperfusion. The AaDO2 was significantly (p < .05) lower in the DHP-PMX group than in the control group at 30, 60, and 120 min after reperfusion. The lt-PVR level differed significantly (p < .05) between the two groups until 240 min after reperfusion. The water content in the control group was significantly (p < .05) higher than that in the DHP-PMX group at 240 min after reperfusion. Lung tissues at 120 and 240 min after reperfusion were better preserved pathologically in the DHP-PMX group.

CONCLUSION

DHP-PMX therapy reduced warm ischemia-reperfusion injury in the lung using a canine model.

The effect of continuous veno-venous hemofiltration or direct hemoperfusion with polymyxin B-immobilized fiber on neutrophil respiratory oxidative burst in patients with sepsis and septic shock

Neutrophil activates and injures tissues and organs during sepsis or septic shock. Blood purification therapies such as continuous veno-venous hemofiltration (CVVH) and direct hemoperfusion with polymyxin-immobilized fiber (PMX-DHP) have been used for the treatment of sepsis and septic shock, however, the effects of such therapies on neutrophil activation have previously been poorly understood. We sought to evaluate neutrophil reactive oxygen species (ROS), especially H2O2 production, in the pathophysiology of sepsis or septic shock and the effect of CVVH or PMX-DHP on neutrophil ROS. Seven critically ill septic patients requiring CVVH (and 12 matched septic patients who did not require CVVH as control) and seven septic shock patients treated with PMX-DHP were studied. We found that patients with sepsis or septic shock had significantly higher levels of neutrophil ROS compared with normal volunteers (183 +/- 42, 292 +/- 90, and 103 +/- 30) (P < 0.05, and < 0.005). Neutrophil ROS did not change over time in patients treated either with CVVH or without CVVH. In contrast, neutrophil ROS significantly inhibited PMX-DHP treatment in patients with septic shock (pretreatment; 292 +/- 88 vs. post-treatment; 205 +/- 93, P < 0.05). In conclusion, neutrophil ROS was significantly enhanced in the sepsis or septic shock affected patients. CVVH did not affect neutrophil ROS while PMX-DHP significant inhibited neutrophil ROS.

Polymyxin B immobilized column is effective for hydrochloric acid-induced lung injury in rats

The purpose of this study was to examine whether hemoperfusion using polymyxin B (PMX) immobilized column improves hydrochloric acid (HCl)-induced lung injury. Rats weighing 350 g underwent hemoperfusion for 30 min at a flow rate of 120 ml/h after the intratracheal instillation of hydrochloric acid or water. Rats were divided into those that underwent hemoperfusion, with or without polymyxin B column, 30 min after HCl instillation ("HCl+PMX" and "HCl"), and hemoperfusion with or without polymyxin B column 30 min after water instillation ("Aqua+PMX" and "Aqua"). Systolic blood pressure, arterial blood gas analysis and white blood cell count and neutrophils were measured before, 1 and 3h after hemoperfusion. Plasma and bronchoalveolar lavage fluid concentrations of growth-related oncogene/cytokine-induced neutrophils chemoattractant-1 (GRO/CINC-1) were measured at 1 and 3h after hemoperfusion. Arterial oxygen concentrations were higher in the "HCl+PMX" group than in the "HCl" group. The total numbers of cells and neutrophils in the bronchoalveolar lavage fluid were significantly higher in the "HCl" group than in the others. The GRO/CINC-1 concentrations in the plasma and bronchoalveolar lavage fluid and the albumin ratio in the "HCl+PMX" group were significantly lower than in the "HCl" group. Direct hemoperfusion using polymyxin B immobilized column treatment affects the recruitment of circulating neutrophils to the lungs due to the decrease in mediators for non-endotoxic lung injury.

Beneficial effect of polymyxin B-immobilized fiber column (PMX) hemoperfusion treatment on acute exacerbation of idiopathic pulmonary fibrosis

OBJECTIVE

This study was aimed to investigate the effect of polymyxin B-immobilized fiber column (PMX) hemoperfusion treatment on the acute exacerbation of idiopathic pulmonary fibrosis (IPF).

PATIENTS AND METHODS

Six patients with a clinical diagnosis of idiopathic pulmonary fibrosis (IPF) who developed acute exacerbation were included in this study. Although five of six patients were treated with high-dose corticosteroid therapy, mechanical ventilation was necessary for all six patients due to severe respiratory failure. Blood endotoxin levels were undetectable in all patients. PMX treatment was performed on these six patients.

RESULTS

In four of six patients, alveolar-arterial difference of oxygen (AaDO(2)), serum KL-6 and lactate dehydrogenase (LDH) were improved after PMX treatment. These four patients were successfully weaned from mechanical ventilation and survived more than 30 days after the initial PMX treatment.

CONCLUSION

These data suggest a potential beneficial effect of PMX treatment on acute exacerbation of IPF.

A pilot-controlled study of a polymyxin B-immobilized hemoperfusion cartridge in patients with severe sepsis secondary to intra-abdominal infection

Endotoxin is an important pathogenic trigger for sepsis. The polymyxin B-immobilized endotoxin removal hemoperfusion cartridge, Toraymyxin (hereafter PMX), has been shown to remove endotoxin in preclinical and open-label clinical studies. In a multicenter, open-label, pilot, randomized, controlled study conducted in the intensive care unit in six academic medical centers in Europe, 36 postsurgical patients with severe sepsis or septic shock secondary to intra-abdominal infection were randomized to PMX treatment of 2 h (n = 17) or standard therapy (n = 19). PMX was well tolerated and showed no significant side effects. There were no statistically significant differences in the change in endotoxin levels from baseline to 6 to 8 h after treatment or to 24 h after treatment between the two groups. There was also no significant difference in the change in interleukin (IL)-6 levels from baseline to 6 to 8 h after treatment or to 24 h after treatment between the two groups. Patients treated with PMX demonstrated significant increases in cardiac index (CI; P = 0.012 and 0.032 at days 1 and 2, respectively), left ventricular stroke work index (LVSWI, P = 0.015 at day 2), and oxygen delivery index (DO2I, P = 0.007 at day 2) compared with the controls. The need for continuous renal replacement therapy (CRRT) after study entry was reduced in the PMX group (P = 0.043). There was no significant difference between the groups in organ dysfunction as assessed by the Sequential Organ Failure Assessment (SOFA) scores from day 0 (baseline) to day 6. Treatment using the PMX cartridge is safe and may improve cardiac and renal dysfunction due to sepsis or septic shock. Further studies are needed to prove this effectiveness.

Effect of hemoperfusion using polymyxin B-immobilized fiber on IL-6, HMGB-1, and IFN gamma in a neonatal sepsis model

To evaluate effects of polymyxin B direct hemoperfusion (PMX-DHP) on a neonatal sepsis cecal ligation and perforation (CLP) model, in 24 anesthetized and mechanically ventilated 3-d-old piglets, 16 were assigned to CLP and an arteriovenous extracorporeal circuit from 3 h until 6 h post-CLP, with a PMX-column in PMX-DHP-treated group (8 piglets) and 8 as sham. Plasma lipopolysaccharide (LPS) was measured at before CLP and at 3 and 9 h. Changes in mean systemic blood pressure (mSBP), mean pulmonary blood pressure, serum IL-6, tumor necrosis factor alpha, interferon gamma, and highly mobile group-1 box protein were measured before CLP and at 1, 3, 6, and 9 h. LPS was lower in the sham and PMX-DHP groups than in the control at 9 h. The mSBP was higher in the sham and PMX-DHP groups than in the control at both 6 h. IL-6 was lower in the sham and PMX-DHP groups than in the control at 6 h. HMGB-1 was lower in the PMX-DHP group than in the control at 6 h. IFN-gamma was only detected in the control group at 9 h. Survival times in the PMX-DHP group were longer than in the control. Thus, PMX-DHP improved septic shock in a neonatal septic model.

[Pathophysiological role of endotoxins, a common denominator to various diseases]

A growing number of investigations point to endotoxin or lipopolysaccharide as a central player in many pathophysiological states and diseases. Endotoxins are one of the most toxic biological contaminants continuously shed by both dead and live Gram negative bacteria. Endotoxins induce the primitive form of defense called innate immunity. Endotoxins have been related to inflammatory reactions observed in patients suffering from respiratory distress syndrome, multiorgan failure and septic shock, hepatic diseases, or in subjects affected by graft versus host disease after allogeneic transplantation. As our understanding of the molecular mechanisms underlying pathologies progresses, more diseases involving endotoxins emerge. Although these illnesses are multifactorial, the objective of this article is to review some of the common and distinct processes involving endotoxins in various disease states.