Supplementum 163 - Swiss Medical Weekly

11 S SWISS MED WKLY 2008;138(Suppl 163) · www.smw.ch
Free Communications 3 – SSAI / SGAI
48
Cytokine production by peripheral blood cells following therapy
with a combined vaccine of allergen and QbG10
V. Manolova 1 , A. Flace 1 , P. Maurer 1 , P. Saudan 1 , G. Senti 2 , T. Kündig 2 ,
M. Bachmann 1 .
1 Cytos Biotechnology AG (Schlieren, CH); 2 University Hospital
(Zurich, CH)
Immunological sensitization to common environmental allergens
results in diseases such as allergic rhinitis. Susceptible individuals
develop allergen-specific T helper 2 (Th2) immune response
characterized by IgE production, and secretion of IL-4, IL-5 and IL-13
from Th2 cells. We have developed a therapeutic vaccine to treat
allergic diseases, which comprises an allergen extract and Qb viruslike
particle (VLPs) filled with the immunostimulatory sequence (ISS)
G10 (QbG10). A phase IIa clinical study has been conducted to
explore the immunogenicity and the clinical efficacy of the allergy
vaccine. The following study groups were included: i) QbG10+Pollen
(QbG10 combined with grass pollen formulated in Alum); ii) QbG10
alone; iii) QbG10 adsorbed to Alhydrogel; iv) PBS and v) PBS mixed
with Alhydrogel. PBMC isolated from the volunteers before and after
treatment were stimulated with either medium or grass pollen extract
for six days in vitro and IL-5, IL-10, IFN gamma and TNF alpha in the
supernatants were measured using the flex set cytometric bead array
(Becton Dickinson).
Among the tested cytokines, the Th2 cytokine IL-5 dominated the
pollen-specific response of PBMC from allergic volunteers before
treatment. Upon vaccination, a decrease of IL-5 was detected in the
majority of the volunteers, regardless of the treatment. However,
pollen-specific IL-5 was significantly decreased only following
QbG10+Pollen therapy (p = 0.006). None of the other groups showed
a significant reduction in pollen-specific IL-5. Furthermore, IFN
gamma and TNF alpha were produced at very low levels and did not
change upon treatment.
Interestingly, up to 70% of the study volunteers’ PBMC released
IL-10 following treatment with combination vaccine consisting of
allergen and QbG10. As a result, the levels of IL-10 in this group
significantly increased upon treatment (p = 0.003). The increase in
IL-10 upon treatment with QbG10+Pollen was also statistically
significant if compared to the change in IL-10 levels in both placebo
groups (PBS – p = 0.049 and PBS in Alum – p = 0.014).
Taken together, these data suggest that treatment of allergic
volunteers with a combined vaccine of allergen and QbG10 results in
pollen-specific downmodulation of the Th2 cytokine IL-5 and
upregulation of the regulatory cytokine IL-10.
49
Inhibition of mediator release by designed ankyrin repeat
proteins against the alpha chain of the high affinity receptor for
IgE
A. Eggel1 , E. Keller-Gautschi1 , P. Amstutz2 , B.M. Stadler1 , M. Vogel1 .
1 Universität Bern (Bern, CH); 2 Molecular Partners AG (Zürich, CH)
Background: In atopic disease the activation of mast cells and
basophils by aggregation of the high-affinity receptor for IgE (Fc
epsilon RI) results in the release of various inflammatory mediators. To
prevent this degranulation either inhibitory anti-IgE or anti-Fc epsilon
RI antibodies could be used. Several monoclonal anti-Fc epsilon RI
alpha antibodies inhibiting the interaction of IgE with its receptor were
described so far but most of them are anaphylactogenic.
Designed ankyrin repeat proteins (DARPins) represent a novel protein
scaffold for high-affinity binding molecules that might be used as an
alternative to antibodies. They consist of 33 amino acids long repeat
modules stacking together to form a hydrophobic core and a large
accessible surface for target binding. Combinatorial DARPin libraries
with randomized interaction surfaces containing either two (N2C) or
three (N3C) internal repeat modules have been generated.
Methods: DARPins against the extracellular part of Fc epsilon RI
alpha were selected using ribosome display. N2C and N3C binders
were characterized by ELISA and surface plasmon resonance and
tested for inhibition of receptor cross-link induced degranulation
using rat basophilic leukemia cells stably transfected with human Fc
epsilon RI alpha (RBL-2H3-hu alpha).
Results: Selected binders recognized Fc epsilon RI alpha with high
affinity and showed no cross-reactivity to any other tested protein.
Two DARPins binding to different epitopes on Fc epsilon RI alpha
were expressed as bivalent and bispecific constructs. We
demonstrated that one of these bispecific DARPins prevents receptor
cross-link induced degranulation of RBL-2H3-hu alpha cells.
Moreover our bispecific DARPin inhibited mediator release in the
same range as the humanized monoclonal anti-IgE antibody
Omalizumab (Xolair ® ) which is currently used to treat moderate-tosevere
asthma.
Conclusion: Our data demonstrated that anti-Fc epsilon RI alpha
DARPins might represent a novel approach in the treatment of allergy
as an alternative to Omalizumab. The therapeutic potential of a
DARPin in vivo is not yet determined and has to be further evaluated.
50
House dust mite avoidance: effect on FENO
C.E. Pichler1 , P. Taramarcaz2 , W.J. Pichler1 .
1 Allergiepoliklinik (Bern, CH); 2 Hôpitaux Universitaires (Genève, CH)
Background: Allergy to house dust mites is a main cause for
perennial rhinitis and allergic asthma. It goes along with an elevated
FENO level due to allergen contact and eosinophilic airway
inflammation. To investigate the usefulness of recommendations for
mite avoidance, we measured symptom scores, bronchial FENO,
FEV1, and blood eosinophils/ECP levels before and after mite
avoidance procedures.
Materials and methods: 34 patients with mite allergy and FENO
levels >35 ppb (normal levels