In vivo effects of C1-esterase inhibitor on innate immune response during endotoxemia in human - VECTOR II study

C1-esterase inhibitor (C1 INH) is a major inactivator of both the complement
and contact system. C1 INH is an acute phase protein, which is normally
excreted during inflammation. C1 INH substitution has shown to reduce
complement and contact activation and, thereby, reducing oedema and
polymorphnuclear leukocyte (PMN) infiltration into tissue. Animal models have
shown that C1 INH improves outcome both given before and shortly after
induction of severe inflammation through sepsis or surgical trauma, but the
underlying mechanism remains to be elucidated. In vitro C1 INH directly
inhibits PMN functions. Since PMN*s are important effector cells in post-injury
immunological pathology, inhibition of post-injury inflammation might be for a
great part due to this entity.
A previous study from our laboratory showed that administration of the drug C1
INH has a significantly effect on the humoral response, by reducing the
concentration of circulating pro-inflammatory cytokines during human
experimental endotoxemia (Dorresteijn et al, Crit Med Care, Jan 2011).

In this study we will administer the C1 INH before LPS injection. We expect
that this study will give us an insight in the pathophysiology of the cellular
response caused by the LPS induced systemic inflammation, in volunteers with
and without pre-treatment with C1-INH

- Primary objective: The effect of C1-INH prior to induction of a systemic
inflammation by endotoxin (E. coli lipopolysaccharide), on the leukocyte
phenotype, activation and mobilization.
- Secondary objectives:
- Determine the effect of C1-esterase inhibition on the LPS induced
pro-inflammatory response (IL-6, TNF-α and IL-1β) and increase of anti-
inflammatory response (IL-10).
- Determination of neutrophil lifespans in blood, and post-mitotic pool
transit times. These lifespans will be compared between healthy
volunteers treated with or without C1-INH before LPS treatment.

Double-blind placebo-controlled randomized intervention pilot study in healthy
human volunteers during experimental endotoxemia.

Subjects will be tested in 2 separate sequential sessions. A total of 20
subjects will be randomly assigned to one of two dosing groups in a 1:1 ratio:
C1 INH followed (n=10) or placebo (n=10). All subject will then receive a LPS
injection.

Healthy volunteers will receive 100 U/kg U C1 INH or placebo half an hour
before the induction of endotoxemia. Endotoxemia will be achieved by injection
of LPS derived from E coli O:113 (2 ng/kg iv in 1 minute).

Before LPS injection, prehydration will be performed by infusion of 1.5 L 2.5%
glucose/0.45% saline solution in 1 hour.

3 till 11 days (time points differ per subject) before the actual endotoxin
experiment, the subject will be orally administered 1g of deuterated glucose
per kilogram bodyweight in 12 doses over a period of 6 hours

A medical interview and physical examination are part of this study.
During endotoxemia, volunteers will be monitored on the research unit of the
intensive care unit at the Radboud UMC. The participants will receive an
arterial line to facilitate blood pressure monitoring and blood sampling. The
arterial line will be placed under local anaesthesia using 2% lidocaine.
Furthermore, a venous cannula will be placed for the administration of fluids
and LPS.
There will be mild discomfort associated with participation in this study, as
LPS induces flu-like symptoms for approximately 4-6 hours. This model of
systemic inflammation has been applied for many years in various research
centers in the world. Endotoxin administration is considered safe and no
long-term effects have ever been documented. At the Radboud UMC, over 350
volunteers have received LPS. Therefore, there is sufficient experience with
this model in this center.

Administration of C1 INH has been safely in high concentrations. C1 INH is a
normal constituent of human blood. Side effects of C1 INH administration may
include: injection site reaction (eg rash), allergic or anaphylactoid
reactions. These side effects are rare (> 1/10.000 and <1/1000).

For the DNA 2H enrichment the subjects will need to drink 1 g of 2H-glucose per
kg (dissolved in water at 0.4 mg/l) in twelve small portions during 6 hours, 3
to 11days (time points differ per volunteer) before the actual endotoxemia
administration.
Intake of 2H-glucose has been performed in several other studies and it is
considered safe, without side effects.

Approximately 350 ml blood will be drawn during each entire LPS experiment.