Dependence of Positive Effects of Granulocyte Colony-stimulating Factor on the Antibiotic Regimen: Evaluation in Rats with Polymicrobial Peritonitis

Sepsis leads to thyroid impairment and dysfunction in rat model

Sepsis was a systemic response to a local infection. Apoptosis was observed in the experimental sepsis. In this study, cecal ligation and puncture (CLP)-induced sepsis was established in rats. We found that sepsis decreased thyroid hormone levels, including triiodothyronine (T3), thyroxine (T4), free T3 (fT3), and free T4 (fT4). Besides, we detected the increasing expression level of Caspase-3 and increasing ratio of TUNEL positive cells in the thyroid after sepsis. Furthermore, a series of pathological ultrastructural changes were observed in thyroid follicular epithelial cells by CLP-induced sepsis. This study established a sepsis animal model and provided the cellular and molecular basis for decoding the pathological mechanism in thyroid with the occurrence of sepsis.

Sepsis: in search of cure

INTRODUCTION

Sepsis is a complex inflammatory disorder believed to originate from an infection by any types of microbes and/or their products. It is the leading cause of death in intensive care units (ICUs) throughout the globe. The mortality rates depend both on the severity of infection and the host's response to infection.

METHODS

Literature survey on pathobiology of sepsis in general and failure of more than hundred clinical trials conducted so far in search of a possible cure for sepsis resulted in the preparation of this manuscript.

FINDINGS

Sepsis lacks a suitable animal model that mimics human sepsis. However, based on the results obtained in animal models of sepsis, clinical trials conducted so far have been disappointing. Although involvement of multiple mediators and pathways in sepsis has been recognized, only few components are being targeted and this could be the major reason behind the failure of clinical trials.

CONCLUSION

Inability to recognize a single critical mediator of sepsis may be the underlying cause for the poor therapeutic intervention of sepsis. Therefore, sepsis is still considered as a disease-in search of cure.

Balancing Innate Immunity and Inflammatory State via Modulation of Neutrophil Function: A Novel Strategy to Fight Sepsis

Sepsis and SIRS (systemic inflammatory response syndrome) belong to a severe disease complex characterized by infection and/or a whole-body inflammatory state. There is a growing body of evidence that neutrophils are actively involved in sepsis and are responsible for both release of cytokines and phagocytosis of pathogens. The neutrophil level is mainly regulated by G-CSF, a cytokine and drug, which is widely used in the septic patient with neutropenia. This review will briefly summarize the role of neutrophils and the therapeutic effect of G-CSF in sepsis. We further suggest that targeting neutrophil function to modulate the balance between innate immunity and inflammatory injury could be a worthwhile therapeutic strategy for sepsis.

Anastomotic stability and wound healing of colorectal anastomoses sealed and sutured with a collagen fleece in a rat peritonitis model

BACKGROUND/OBJECTIVE

Anastomotic insufficiency is associated with increased morbidity and mortality. A collagen fleece that supports anastomosis is effective for preventing anastomosis insufficiency. The objective of this study was to compare between the stability of sutured anastomoses and that of anastomoses sealed with a thrombin/fibrinogen-coated collagen fleece in a rat peritonitis model.

METHODS

In 72 male Wistar rats, peritonitis was induced with a specially prepared human fecal solution. Surgery at the rectosigmoid junction was performed 24-36 hours later. The different anastomotic techniques used were circular sutured anastomoses, semicircular sutured anastomosis and closure of the anterior wall with collagen patch, and complete closure with a collagen fleece. Bursting pressure, histology of anastomosis, mRNA expression of collagen types I and III, matrix metalloproteinase-13, and vascular endothelial growth factor (VEGF) were investigated after 24 hours, 72 hours, and 120 hours.

RESULTS

All animals developed peritonitis of comparable severity. There were no differences in bursting pressures between the three suture techniques after 24 hours, 72 hours, or 120 hours. Anastomoses sealed with a collagen fleece appeared to be slightly less stable only at 24 hours, whereas they appeared to be more stable than semisutured or fully sutured anastomoses at 72 hours and 120 hours. Sealing with a collagen fleece was associated with an increase in granulation tissue, higher mRNA levels for collagen types I and III, and higher VEGF compared to sutured anastomoses.

CONCLUSION

The use of a thrombin/fibrinogen-coated collagen fleece showed similar efficacy to conventional sutures in colorectal anastomoses in the presence of peritonitis inflammation, and may provide additional benefits due to an increase in mature granulation tissue.

Characteristics of clinical sepsis reflected in a reliable and reproducible rodent sepsis model

BACKGROUND

Sepsis models are frequently based on induction of peritonitis, with cecal ligation and puncture reflecting the prototypical model. However, there is an ongoing discussion about the limitations of these models due to their variability in progression and outcome. Since standardization is a cornerstone of experimental models, we aimed to develop a reliable and reproducible procedure for induction of peritonitis.

MATERIALS AND METHODS

A human stool batch was processed for -80° storage. For induction of peritonitis in fluid-resuscitated rats, a defined volume of stool suspension from this batch was injected intraperitoneally. For characterization of the model, physiologic and inflammatory changes were evaluated after sepsis induction. Survival analyses with the same batch were repeated in four independent experiments over a time period of 16 mo.

RESULTS

The polymicrobial infection resulted in severe peritoneal inflammation with a systemic increase in cytokines. The mortality rate at 15 h was 29% and this was reproducible over a 16 mo time period. If antibiotic treatment was applied, a 50% survival was achieved. Laboratory markers indicated a progressive multi-organ dysfunction, while blood gas analysis showed respiratory compensation of a metabolic acidosis, and maintenance of PaO(2). Intravital microscopy of the liver revealed an impaired microcirculation. A decreased hemostatic potential was demonstrated by rotational thromboelastometry. Despite clinical recovery within 3 d, surviving animals showed laboratory and histologic signs of persisting inflammation even after 2 wk.

CONCLUSIONS

This model reflects many features of human sepsis. Application of an infectious focus that is both quantitatively and qualitatively defined assures high reproducibility. Moreover, the procedure is simple and can be easily standardized.

Plasminogen activator, but not systemic antibiotic therapy, prevents abscess formation in an experimental model of secondary peritonitis

Background

Intra-abdominal abscesses are sources of recurrent or ongoing abdominal sepsis. They are an important target for prevention and treatment during or after surgical treatment of peritonitis. Experimental data suggest that fibrinolytic therapy may be effective when antibiotics are not.

Methods

Peritonitis was induced via intra-abdominal injection of a faeces and bacteria mixture in male Wistar rats. Surgical debridement was performed after 1 h. Next to untreated controls, animals were treated with antibiotics (ceftriaxone plus metronidazole), recombinant tissue plasminogen activator (rtPA) or both. Abdominal fluid samples were taken at 24, 72 and 120 h for interleukin 6, interleukin 10 and tumour necrosis factor α measurements and cell counts. After 5 days the abdomen was inspected for the presence of abscesses.

Results

Antibiotics did not significantly affect abscess formation. However, giving rtPA significantly reduced the number of rats with abscesses and the abscess load per rat, both in the absence and presence of concomitant antibiotic therapy. No adverse side-effects were observed and no meaningful differences in the local inflammatory response were found.

Conclusion

In this rat model, rtPA consistently reduced abscess formation after surgical treatment of secondary peritonitis. It therefore represents a promising adjuvant to conventional therapy.

Differential effects of antibiotics in combination with G-CSF on survival and polymorphonuclear granulocyte cell functions in septic rats

BACKGROUND

In addition to their antimicrobial activity, antibiotics modulate cellular host defence. Granulocyte-colony stimulating factor (G-CSF) is also a well known immunomodulator; however little is known about the interactions of G-CSF with antibiotics. We investigated in septic rats the effects of two antibiotic combinations with G-CSF.

METHODS

In two clinic modelling randomised trials (CMRTs), male Wistar rats were anesthetized, given antibiotic prophylaxis, had a laparotomy with peritoneal contamination and infection (PCI), and were randomly assigned (n = 18 rats/group) to: 1) PCI only; 2) PCI+antibiotic; and, 3) PCI+antibiotic+G-CSF prophylaxis (20 mug/kg, three times). This sequence was conducted first with 10 mg/kg coamoxiclav, and then with ceftriaxone/metronidazole (Cef/met, 10/3 mg/kg). In additional animals, the blood cell count, migration and superoxide production of PMNs, systemic TNF-alpha and liver cytokine mRNA expression levels were determined.

RESULTS

Only the combination coamoxiclav plus G-CSF improved the survival rate (82 vs. 44%, p < 0.001). Improved survival with this combination was accompanied by normalised antimicrobial PMN migratory activity and superoxide production, along with normalised systemic TNF-alpha levels and a reduced expression of TNF-alpha and IL-1 in the liver.

CONCLUSION

There are substantial differences in the interaction of antibiotics with G-CSF. Therefore, the selection of the antibiotic for combination with G-CSF in sepsis treatment should be guided not only by the bacteria to be eliminated, but also by the effects on antimicrobial functions of PMNs and the cytokine response.

Effects of granulocyte-colony stimulating factor on the polymorphonuclear leukocyte activity and the course of sepsis in rats with experimental peritonitis

PURPOSE

Polymorphonuclear leucocytes (PML) play an essential role in the host immune response to severe infections. The effects of granulocyte-colony stimulating factor (G-CSF) on the PML immune functions during serious abdominal infection and course of sepsis, and on the survival in rats with peritonitis are the main subjects of this study.

METHODS

The first phase of the study was carried out on 30 Wistar-albino rats equally divided into three groups; Group 1 (control) sham laparotomy; Group 2 (peritonitis); and Group 3 (peritonitis+G-CSF) with fecal peritonitis created by a cecal puncture. At postoperative hours 3, 12, and 24, 0.5 ml normal saline was injected subcutaneously in groups 1 and 2, and 0.5 ml solution containing 50 microg/kg of G-CSF in group 3. The phagocytic and chemotactic activities of neutrophils and monocytes were evaluated by a flow cytometry analysis. The plasma lactate concentrations were assessed as a marker of tissue perfusion during sepsis. The second phase was a survival analysis, which was observed during 10 days on 20 rats equally divided into two groups; group 1 (peritonitis) and group 2 (peritonitis+G-CSF). 0.5 ml normal saline in group 1 and 50 microg/kg of G-CSF in group 2 was injected subcutaneously at the 3rd hour and twice daily.

RESULTS

Both the neutrophil- (1.636 vs 2.236) and monocyte-related (1.789 vs 2.465) phagocytic activities significantly (P < 0.001) improved after the G-CSF administration in the rats with peritonitis. In addition, the G-CSF treatment significantly (P < 0.0014) improved the chemotactic activity (1.18 vs 2.75) of neutrophils, and partly supported (P < 0.0952) the chemotactic activity (1.69 vs 2.37) of monocytes. The plasma lactate level (1.86 vs 4.9 mmol/l) was significantly (P < 0.0001) increased after septic changes due to experimental peritonitis. On the other hand, the lactate concentration was significantly (P < 0.001) decreased (4.9 vs 2.63 mmol/l) after the G-CSF administration. The survival was 20% at the 4th day and 0 at the 6th day in peritonitis, and 90% at the 4th day (P = 0.0055) and 80% at the 6th day (P = 0.0007) days in the peritonitis+G-CSF groups.

CONCLUSION

G-CSF enhances the immune functions of neutrophils and monocytes. The increased activities of these cells have a beneficial effect on the enhancement of the host immune response during severe infections. The improved immune function of PML due to the G-CSF treatment thus ameliorates the survival and the courses of sepsis, which is also defined by tissue perfusion and the cellular oxygen balance, which is affected by septic changes.

Perioperative prophylaxis with granulocyte colony-stimulating factor (G-CSF) in high-risk colorectal cancer patients for an improved recovery: A randomized, controlled trial

BACKGROUND

We aimed to improve the postoperative outcome of high-risk patients (American Society of Anesthesiologists class 3 and 4) recovering from colorectal cancer surgery by using recombinant human G-CSF (filgrastim) as perioperative prophylaxis.

METHODS

In a double-blinded, placebo-controlled trial, 80 patients undergoing left-sided colorectal resection were randomized to filgrastim or placebo. Filgrastim (5 mug/kg) or placebo was administered in the afternoon on day -1, 0, and +1 relative to the operation. Primary endpoints were in a hierarchic order: quality of life (QoL) over time (determined at discharge, 2 and 6 months after operation with the European Organization for Research and Treatment of Cancer questionnaire) and the McPeek recovery score, which measures death and duration of stays in the intensive care unit and hospital. Predefined secondary endpoints were global QoL, subdomains of QoL, postoperative recovery, duration of stay, 6-month overall survival, complication rates, and cellular and immunologic parameters.

RESULTS

There were no significant differences in both primary endpoints between the treatment groups. A significant improvement (P < .05) was obtained by filgrastim prophylaxis in the QoL subdomain family life /- social functioning,; thus, more patients recovered to their preoperative state (14 vs 4 with placebo) as determined by structured interviews. Duration of hospital stay (14 vs 12 days) and noninfectious complications were decreased from 8% to 3%.

CONCLUSIONS

High-risk patients undergoing major operation for colorectal cancer profited from filgrastim prophylaxis with regard to duration of hospital stay, noninfectious complications, social QoL, and subjective recovery from operation. These endpoints, however, were secondary, and the primary endpoints (overall QoL and the McPeek index) did not show comparable benefits. A new confirmatory trial with the successful endpoints of this trial, as well as a cost analysis, will be needed to confirm the results before a general recommendation for the prophylactic use of G-CSF in high-risk cancer patients can be given.

Granulocyte colony-stimulating factor prophylaxis improves survival and inflammation in a two-hit model of hemorrhage and sepsis

OBJECTIVE

We evaluated the effects of a granulocyte-colony stimulating factor (G-CSF) prophylaxis in two clinically relevant situations, hemorrhage on the day before infection (e.g., trauma) and acute hemorrhage followed subsequently by infection (e.g., operative complication). A two-hit model of hemorrhage and polymicrobial peritoneal contamination and infection (PCI) was used to assess the influence of G-CSF on the outcome, bacterial clearance, and cytokine pattern.

DESIGN

Clinic modeling randomized laboratory trial.

SETTING

University laboratory.

SUBJECTS

One hundred thirty-two male rats.

INTERVENTIONS

In trial 1 we compared a) preoperative PCI only; b) preoperative hemorrhage plus PCI; and c) hemorrhage plus PCI plus G-CSF prophylaxis (n=18 rats/group). In trial 2, intraoperative hemorrhage was assessed with the same trial design. Primary end point was survival at 120 hrs. In trial 2 additionally, six rats per group and six naive control rats were used for secondary end point analysis.

MEASUREMENTS AND MAIN RESULTS

Primary end point was mortality at 120 hrs. Secondary end points were granulocyte counts, bacterial clearance, and local cytokine levels. In trial 1 survival rate was 56% after PCI only, 17% after hemorrhage plus PCI, and 61% after hemorrhage plus PCI plus G-CSF (p<.01). In trial 2 survival rate was 33% after PCI only, 17% after hemorrhage plus PCI, and 50% after hemorrhage plus PCI plus G-CSF (p<.05). In trial 2, neutrophil counts were doubled to 66% 1 hr after hemorrhage (p<.05), colony-forming units of microbes in the lung and liver were halved to 166+/-56 and 134+/-28 colony-forming units (p<.05 for liver), and the macrophage inflammatory protein-2 expression in the lung was halved to 0.88+/-0.06 pg of complementary DNA (p<.05) by G-CSF prophylaxis compared with hemorrhage and PCI.

CONCLUSIONS

Hemorrhage (first hit) sensitized the host for a second hit of polymicrobial PCI independent of the timing. G-CSF prophylaxis improved survival and clearance of microbes and reduced the proinflammatory chemokine macrophage inflammatory protein-2 in the lung.

The effect of G-CSF in an experimental MRSA graft infection in mice

Wound infection after prosthetic material implantation is a troublesome complication with an incidence of 2% to 10%. The effect of granulocyte colony-stimulating factor (G-CSF) was studied in an experimental methicillin-resistant Staphylococcus aureus (MRSA) graft infection model. Eighty adult mice were used. Under general anesthesia an abdominal incision of 2 cm in length was performed. A subcutaneous cavity of 2 x 2 cm in size was created. Polypropylene mesh pieces of 2 x 1 cm and MRSA solution of 0.1ml of 10(8) CFU/mL were used. G-CSF was applied systemically or locally in a dosage of 0.02 MU/30 g body weight. There were 8 groups: group I, wound + MRSA; group II, wound + mesh + MRSA; group III, wound + mesh + MRSA + G-CSF (ip, 48 h before operation); group IV, wound + mesh + MRSA + G-CSF (ip, 24 h before operation); group V, wound + mesh + MRSA + G-CSF (locally, into the cavity); group VI, wound + mesh (incubated in G-CSF solution for 4 h) + MRSA; group VII, wound + mesh + MRSA + G-CSF, ip, 24 h from operation; and group VIII (positive control group), wound + mesh + MRSA + Teicoplanin (0.03 mg/30 g body weight, ip, 1/2 h before operation). Three days after, animals were killed and incisions were examined for possible infection or abscess formation and wound failure. Meshes were removed; after vortexing and dilution, samples were incubated with 5% agar media. Results of bacterial incubation were evaluated 24 h and 48 h later. There were symptoms of wound infection and abscess formation in all groups except group VIII. In group VIII, MRSA was isolated in 7 events with a colony count below 10(3). Bacterial counts were above 10(6) (10(6)-10(8)) in all other groups. Thus, it was observed that wound infection could be created with this model, but G-CSF could not prevent the development of wound infection, whether it was administered systemically or locally. Teicoplanin decreased the number of colony-forming units of MRSA, and prevents wound infection in this MRSA wound infection model.