A Possible Therapeutic Role for Adenosine During Inflammation
The adenosine receptor is known for its anti-inflammatory actions and could therefore be a potential target in the treatment of sepsis and septic shock. Stimulation of the adenosine receptor could potentially lead to a decrease in inflammation and tissue damage.
Under normal conditions adenosine is formed either by an intracellular 5`nucleotidase, which dephosphorylates AMP, or by the hydrolysis of S-adenosylhomcysteine by hydrolase. An alternative pathway of AMP degradations is provided by the cytosolic enzyme AMP deaminase (AMPD), which catalyses the irreversible deamination of AMP to inosine monophosphate and ammonia.
In humans four AMPD isoforms have been described, named after the source from which they were initially purified; M (muscle), L (liver), E1 and E2 (erythrocyte), encoded by AMPD1, AMPD2 and AMPD3. Approximately 15-20% of Caucasian and African American individuals are heterozygous or homozygous for the 34C>T variant of AMPD1.
We hypothesize that healthy volunteers who have the polymorphism for AMPD1 have a less severe inflammatory response to LPS and show less (severe) organ failure. This hypothesis is based on the expected higher levels of adenosine in patients with the AMPD1 polymorphism. This hypothesis is strengthened by the fact that patients with coronary artery disease and the AMPD1 polymorphism show improved cardiovascular survival (Anderson JL et al. J Am Coll Cardiol 2000; 36: 1248-52) possibly based on higher adenosine levels by reduced AMPD activity. Furthermore the polymorphism predicts improved clinical outcome in patients with heart failure (Loh E et al. Circulation 1999) also based on a hypothetical elevation of adenosine.
We hypothesize that:
The C34T-polymorphism of the enzyme AMP-deaminase leads to a decreased inflammatory respons and thereby a decrease of LPS-induced tissue damage.
A second hypothesis is based on the antagonism of the adenosine receptor, by caffeine;
Antagonism of the adenosine receptor by caffeine leads to an increased LPS-induced inflammatory reaction and an increase in (subclinical) tissue damage?
|Endotoxemia||Genetic: AMPD1 polymorphism Drug: Caffeine infusion Drug: placebo||Phase 1|
|Study Design:||Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Prevention
|Official Title:||A Possible Therapeutic Role for Adenosine During Inflammation|
- Hemodynamics; heart rate variability [ Time Frame: 24 hrs after LPS administration ]
- Markers of Inflammation [ Time Frame: 24 hrs after LPS administration ]
- Cytokines [ Time Frame: 24 hrs after LPS administration ]
- Sensitivity to norepinephrine [ Time Frame: 24 hrs after LPS administration ]
- Endothelial-dependent and independent vasorelaxation [ Time Frame: 24 hrs after LPS administration ]
- Mediators of Vascular reactivity [ Time Frame: 24 hrs after LPS administration ]
- Markers of endothelial damage and circulating endothelial cells [ Time Frame: 24 hrs after LPS administration ]
- Urinary excretion of markers of renal injury [ Time Frame: 24 hrs after LPS administration ]
- Neurologic testing [ Time Frame: 24 hrs after LPS administration ]
- Adenosine and related nucleotide concentrations. [ Time Frame: 24 hrs after LPS administration ]
- Additional blood samples will be drawn for measurement of: TLR-expression, Genetics; micro array analyses and determination of intercellular signalling pathways. [ Time Frame: 24 hrs after LPS administration ]
|Study Start Date:||August 2007|
|Study Completion Date:||August 2008|
|Primary Completion Date:||August 2008 (Final data collection date for primary outcome measure)|
Endotoxin and AMPD1 polymorphism
Genetic: AMPD1 polymorphism
Endotoxin 2ng/kg to subjects with a AMPD1 polymorphism
Endotoxin and intervention with caffeine
Drug: Caffeine infusion
Endotoxin 2ng/kg combined with caffeine. Caffeine (4mg/kg) is used as an adenosine receptor antagonist.
Placebo Comparator: 3
Endotoxin combined with placebo
Endotoxin 2ng/kg combined with saline infusion (0.9%)
Please refer to this study by its ClinicalTrials.gov identifier: NCT00513110
|Radboud University Nijmegen Medical Centre|
|Nijmegen, Gelderland, Netherlands, 6500 HB|
|Principal Investigator:||Peter Pickkers, MD,PhD||Radboud University|