Background:
We aimed to study
the reproducibility
of several
biomarkers of
allergic rhinitis to
investigate their
potential as outcome
measures in clinical
intervention trials.
Furthermore, we
investigated the
kinetics of the
biomarkers studied
in nasal lavage and
brush material
following a
placebo-controlled
nasal allergen
challenge.
Methods: We
performed a skin
prick test and
measured serum
specific
immunoglobulin (Ig)
E levels and
inflammatory
biomarkers in nasal
lavage and brush
material in 20
patients with
allergic rhinitis on
2 separate days
(washout, 14-21
days). The patients
were then randomly
assigned to undergo
an intranasal
challenge with a
relevant allergen (n
= 10) or diluent (n
=10) in order to
assess the kinetics
of several
biomarkers of
allergic airway
inflammation in
nasal lavage and
brush samples.
Results:
Baseline serum IgE
levels and skin
wheal sizes were
highly reproducible
measurements, with a
coefficient of
variation (CV) of
13.4% and 18.2%,
respectively. This
was not the case
with the majority of
inflammatory
biomarkers, whose CV
varied considerably
(range,
6.1%-224.1%). The
nasal allergen
challenge induced an
increase in
composite symptom
scores in all
patients. Compared
to placebo, tryptase
(P = .004),
eosinophilic
cationic protein (ECP)
(P =.03) and
α2-macroglobulin (P
= .002) were
increased in nasal
lavage at 20 minutes
post allergen. Nasal
lavage ECP levels
and nasal brush
eosinophils were
still significantly
increased at 7 hours
(P =.03 and P =.04),
but all statistical
significance had
been lost at 24
hours post
challenge.
Conclusion:
Serum specific IgE
assays and skin
prick tests
exhibited good
reproducibility in
patients with
clinically stable
allergic rhinitis.
We were also able to
investigate the
kinetics of
allergen-induced
upper airway
inflammatory markers
in nasal lavage and
brush material.
Hence, nasal
allergen challenge,
when used in
combination with
nasal lavage and
brush sampling, is a
suitable research
tool for early
drug development.
Key words:
Allergic rhinitis.
Biomarkers. Nasal
allergen challenge.
Reproducibility.
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