Effects of intra-abdominal administration of recombinant tissue plasminogen activator on coagulation, fibrinolysis and inflammatory responses in experimental polymicrobial peritonitis

Hypofibrinolysis induced by tranexamic acid does not influence inflammation and mortality in a polymicrobial sepsis model

The biological relevance of fibrinolysis to the host response to sepsis is illustrated by pathogens such as S. pyogenes and Y. pestis, whose virulence factors are proteins that challenge the balance between pro- and anti-fibrinolytic factors of the host, and by the consistent finding of hypofibrinolysis in the early stages of sepsis. Whether this hypofibrinolytic response is beneficial or detrimental to the host, by containing the spread of pathogens while at the same time limiting the access of immune cell to infectious foci, is still a matter of debate. Tranexamic acid (TnxAc) is an antifibrinolytic agent that is being increasingly used to prevent and control bleeding in conditions such as elective orthopedic surgery, trauma, and post-partum-hemorrhage, which are frequently followed by infection and sepsis. Here we used a model of polymicrobial sepsis to evaluate whether hypofibrinolysis induced by TnxAc influenced survival, tissue injury and pathogen spread. Mice were treated with two doses of TnxAc bid for 48h, and then sepsis was induced by cecal ligation and puncture. Despite the induction of hypofibrinolysis by TnxAc, no difference could be observed in survival, tissue injury (measured by biochemical and histological parameters), cytokine levels or pathogen spread. Our results contribute with a new piece of data to the understanding of the complex interplay between fibrinolysis and innate immunity. While our results do not support the use of TnxAc in sepsis, they also address the thrombotic safety of TnxAc, a low cost and widely used agent to prevent bleeding.

Impact of endothelial microparticles on coagulation, inflammation, and angiogenesis in age-related vascular diseases

Endothelial microparticles (EMPs) are complex vesicular structures that originate from plasma membranes of activated or apoptotic endothelial cells. EMPs play a significant role in vascular function by altering the processes of inflammation, coagulation, and angiogenesis, and they are key players in the pathogenesis of several vascular diseases. Circulating EMPs are increased in many age-related vascular diseases such as coronary artery disease, peripheral vascular disease, cerebral ischemia, and congestive heart failure. Their elevation in plasma has been considered as both a biomarker and bioactive effector of vascular damage and a target for vascular diseases. This review focuses on the pleiotropic roles of EMPs and the mechanisms that trigger their formation, particularly the involvement of decreased estrogen levels, thrombin, and PAI-1 as major factors that induce EMPs in age-related vascular diseases.

Efficacy and safety of active negative pressure peritoneal therapy for reducing the systemic inflammatory response after damage control laparotomy (the Intra-peritoneal Vacuum Trial): study protocol for a randomized controlled trial

Background

Damage control laparotomy, or abbreviated initial laparotomy followed by temporary abdominal closure (TAC), intensive care unit resuscitation, and planned re-laparotomy, is frequently used to manage intra-abdominal bleeding and contamination among critically ill or injured adults. Animal data suggest that TAC techniques that employ negative pressure to the peritoneal cavity may reduce the systemic inflammatory response and associated organ injury. The primary objective of this study is to determine if use of a TAC dressing that affords active negative pressure peritoneal therapy, the ABThera Open Abdomen Negative Pressure Therapy System, reduces the extent of the systemic inflammatory response after damage control laparotomy for intra-abdominal sepsis or injury as compared to a commonly used TAC method that provides potentially less efficient peritoneal negative pressure, the Barker’s vacuum pack.

Methods/Design

The Intra-peritoneal Vacuum Trial will be a single-center, randomized controlled trial. Adults will be intraoperatively allocated to TAC with either the ABThera or Barker’s vacuum pack after the decision has been made by the attending surgeon to perform a damage control laparotomy. The study will use variable block size randomization. On study days 1, 2, 3, 7, and 28, blood will be collected. Whenever possible, peritoneal fluid will also be collected at these time points from the patient’s abdomen or TAC device. Luminex technology will be used to quantify the concentrations of 65 mediators relevant to the inflammatory response in peritoneal fluid and plasma. The primary endpoint is the difference in the plasma concentration of the pro-inflammatory cytokine IL-6 at 24 and 48 h after TAC dressing application. Secondary endpoints include the differential effects of these dressings on the systemic concentration of other pro-inflammatory cytokines, collective peritoneal and systemic inflammatory mediator profiles, postoperative fluid balance, intra-abdominal pressure, and several patient-important outcomes, including organ dysfunction measures and mortality.

Discussion

Results from this study will improve understanding of the effect of active negative pressure peritoneal therapy after damage control laparotomy on the inflammatory response. It will also gather necessary pilot information needed to inform design of a multicenter trial comparing clinical outcomes among patients randomized to TAC with the ABThera versus Barker’s vacuum pack.

Trial registration

ClinicalTrials.gov identifier http://www.clicaltrials.gov/ct2/show/NCT01355094

Tissue plasminogen activator attenuates ventilator-induced lung injury in rats

AIM

To test the hypothesis that the tissue plasminogen activator (tPA) may counteract the inhibitory effect of plasminogen activator inhibitors (PAI) and attenuate lung injury in a rat model of ventilator-induced lung injury (VILI).

METHODS

Adult male Sprague-Dawley rats were ventilated with a HVZP (high-volume zero PEEP) protocol for 2 h at a tidal volume of 30 mL/kg, a respiratory rate of 25 breaths/min, and an inspired oxygen fraction of 21%. The rats were divided into 3 groups (n=7 for each): HVZP+tPA group receiving tPA (1.25 mg/kg, iv) 15 min before ventilation, HVZP group receiving HVZP+vehicle injection, and a control group receiving no ventilation. After 2 h of ventilation, the rats were killed; blood and lungs were collected for biochemical and histological analyses.

RESULTS

HVZP ventilation significantly increased total protein content and the concentration of macrophage inflammatory protein-2 (MIP-2) in the bronchoalveolar lavage fluid (BALF) as well as the lung injury score. Rats that received HVZP ventilation had significantly higher lung PAI-1 mRNA expression, plasma PAI-1 and plasma D-dimer levels than the control animals. tPA treatment significantly reduced the BALF total protein and the lung injury score as compared to the HVZP group. tPA treatment also significantly decreased the plasma D-dimer levels and the HVZP ventilation-induced lung vascular fibrin thrombi. tPA treatment showed no effect on MIP-2 level in BALF.

CONCLUSION

These results demonstrate that VILI increases lung PAI-1 mRNA expression, plasma levels of PAI-1 and D-dimers, lung injury score and vascular fibrin deposition. tPA can attenuate VILI by decreasing capillary-alveolar protein leakage as well as local and systemic coagulation as shown by decreased lung vascular fibrin deposition and plasma D-dimers.

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.